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Development of new nanocomposites using materials from mining industry

Final Report Summary - NANOMINING (Development of new nanocomposites using materials from mining industry)

Executive Summary:

The environmental problems related to jarosite waste are significant all over the world. In many cases jarosite waste contains precious metals and especially silver in quantities that make their extraction attractive.
Silver nanoparticles and silver based nanostructured composites are being frequently used in a variety of biomedical and industrial applications. The Project is aimed on silver recovery from ore waste, silver nanoparticles biosynthesis and fabrication of silver containing nanocomposites and coatings.
The main goals of the Project were to develop:

1. Clean and efficient procedure of silver recovery from waste: Combined Mechanical Activation – Thermal Oxidation Processing (MATO) of jarosite type residues to alleviate and accelerate the precious metal leaching;
2. Combined nanotechnology of biological synthesis (using Mexican plants) of Ag nanoparticles (AgNps) and modification of implant hydroxyapatite (HA) plasma sprayed and electrophoretic coatings;
3. Nanostructuring technology of Silver based nanocomposites manufacturing for electrical contacts.
4. Pilot production and trials (in vitro and in vivo tests) of the developed AgNps modified implants and Ag based nanostructured composites:

Four groups of technologies were developed, scaled-up and studied at the pilot stage:

1. Thermal oxidation and reduction processes of mechanically activated Ag and Zn containing waste products;
2. Green biosynthesis route to obtainAgNp using nopal extracts as reducing and stabilizer agent ions. An eco-friendly and low cost protocol for biosynthesis of silver nanoparticles using nopal extracts has been demonstrated and scaled up to a 2 litres volume. Silver nanoparticles were synthesized in the range 2-18 nm.
3. Plasma Spraying and related on-line diagnostics, sedimentation and electrophoretic technologies for fabrication of HA+Ag and HA+AgNps implant coatings;
4. Silver based nanostructured composite Ag-SnO forming technologies for contacts of electrical systems.

The scanning and transmission electron microscopy, precision chemical analysis, atomic force microscopy, acousto-optical spectroscopy, surface plasmon resonance measurement, particle in flight diagnostics and other methods were applied to study processes and products characterization. The in-vivo and in-vitro tests of AgNps modified implants were performed.

Project Context and Objectives:

Concept and the main Proposal ideas. According to specification of the Project end-users, Silver nanoparticles (Ag Np) and silver based nanostructured composites are being frequently used in a variety of biomedical and industrial applications, such as an antimicrobial agents, lead-free solders, electric contact materials, gas-sensitive sensor, etc. The most complicated Silver using problems are related to:

i) recovery of silver from ore waste materials,
ii) the controlled synthesis of metal nanoparticles of well-defined size, shape and composition,
iii) nanoparticles incorporation into implant surface layers,
iv) synthesis of Silver based nanostructured composites for industrial purposes.

Two application areas of NANOMINING were seen:

i) Development of combined Mechanical Activation – Thermal Oxidation Processing jarosite type residues to alleviate and accelerate the precious metal leaching; and
ii) Development of silver products applications on the base of nanoparticles use.

The main goal of the Project was to develop:

i) Clean and efficient procedure of silver recovery;
ii) Combined nanotechnology of biological synthesis of silver-based crystals and development of technology for deposition of coatings containing nanoparticles on implant surface; and
iii) nanostructuring technology of Silver based nanocomposites manufacturing for electrical contacts.

All of these technologies are based on processing of silver based compounds made of ore wastes which were treated by innovative route.
The essential issue of the new technology is the recovery of Ag using the mechanical activation and thermal oxidation of residues formed during bioleaching process. The ores, tailings or stored metallurgy wastes contain residues from ore processing operations that are characterized by relatively high concentrations of heavy metals. The bioleaching process makes use of bacteria to recover elements from industrial wastes and to decrease potential risk of environmental contamination. The heavy and precious metals remain in the leach residue and form jarosite type compounds difficult to attack. The mechanical activation [P.Balaz E.Dutkova Minerals Engineering, 22(2009)681-694] and thermal oxidation of these compounds alleviate and accelerate the following leaching of gold and silver. Additionally it allows to apply thiourea or thiosulphate leaching instead of cyanide one. It is envisaged to use the microwave heating technology in fluidized bed reactor. The use of microwave energy to facilitate the carbon and other elements oxidation has substantial benefits over traditional roasters, removing need for additional fuel. The mechanical activation by means of ultrafine jet milling is an effective process allowing to drastically accelerate the reactions which are applied for the fractionation of Ag and their recycling for Ag based composite manufacturing.

The biological synthesis approach based on interactions between microorganisms and metals have been well documented [P. Mohanpuria, N. K. Rana, S. K. Yadav, J Nanopart Res 10 (2008)507–517], and the ability of microorganisms to extract and/or accumulate metals is already employed in biotechnological processes such as bioleaching and bioremediation. As an alternative of the conventional methods, the biological methods are considered safe and ecologically adequate to the development of nanomaterials. As a result of the research in the nanoparticles synthesis field, it has been found that unicellular and multicellular organisms posses the capacity to synthesize metallic nanostructures by the reduction of metallic compounds (intra or extra cellular). In the research of other biosynthetic methods, the use of plants and extracts for the nanostructure synthesis is an existing possibility that has not been explored extensively and can emerge as an alternative procedure to the existing physical and chemical methods. The use of plants for the nanoparticles synthesis can offer several advantages over other environmental biological process since it eliminates the elaborated process of microorganism culture maintenance. Hence, the research of vegetal sources for the metallic nanostructure synthesis to be incorporated to conventional materials (polymers, ceramics, etc) represents a great research opportunity.
In this Project, it was proposed to develop the metallic nanostructures synthesis based on the extracts of desert plants as reducing agent and to establish the Ag nanoparticle (Ag Np) generation optimal parameters. Also, it was proposed the characterization and determination of reducing agents in the extracts as well as the antimicrobial properties of the obtained nanostructures for its application in the biomedical materials.

The second aim of Ag Np utilization process was to incorporate the synthesized AgNp into Ti, TiO2 and Hydroxyapatite (HA) implant surface layers deposited by the advanced combined electrophoretic-sintering and plasma spraying technologies.
The electrophoretic method permits the incorporation of other functional materials into the composite HA-biopolymer coatings, including antimicrobial agents, drugs and proteins. The composite coatings allowed controlled release of the antimicrobial agent. Encapsulation of Ag nanoparticles into TiO2 and Hydroxyapatite coating matrix (due to optimized low temperature sintering process), their slow release to the bone-implant interface is expected to alleviate both antimicrobial properties and tissue growth, while assuring the action of the Ag nanocomposite for prolonged periods.
Atmospheric Plasma Spraying (APS) is the most widely applied method to deposit HA coating onto titanium alloy prostheses (>90 % of implant manufacturers use this type of coating deposition). That is why it is important to improve APS coating through its’ doping with AgNp. To reach this call new spraying methods were evaluated: plasma spraying of HA+Ag powder mixture and plasma spraying with gas barrier which allow to saturate coating with AgNp and to ensure their slow release to the surface during implant exploitation.
The continuous supply to a bone-implant area of AgNp with superior antimicrobial properties is the most promising way to solve existing infection problems. It was shown that Ag Np [V. K. Sharma, R. A. Yngard, Y. Lin, Advances in Colloid and Interface Science 145 (2009) 83–96] seem to be more efficient than Ag+ ions in performing antimicrobial activities. The effect of shape on the antibacterial activity on AgNp has only recently been reported.

Ag based alloys and composites are being used in various sliding electric contacts. They are produced by sintering of W–Ag, Graphite-Ag, Ag-SnO (instead of hazardous Ag/CdO composite) and other powder mixtures followed by hot pressing or rolling to increase density.
Composite Nanostructuring with Mechanical Alloying improve both the electrical and friction properties and enhance sintering of systems because it improves dispersion, promotes refinement of the phases and produces composite particles [Rehani, B., Joshi, P.B. Khanna, P.K. Journal of Materials Engineering and Performance (2009) in press]. Novel oxide dispersion strengthened Ag based nanostructured composites synthesized by mechanical alloying and subsequent consolidation via hot pressing exhibits effective electrical and mechanical properties. Maintaining the low friction under high temperature is important for electric contacts, wear resistance requires an additional blend of both hardness and fracture toughness. The composite design concept to be developed provides toughness enhancement through stress minimization, crack deflection, and ductility. These effects were reached as a result of encapsulation of ~40 nm sized nanocrystalline Ag grains in a composite matrix restricts dislocation activity, diverts and arrests macro-crack generation, and maintains a sufficient level of hardness similar to coating designs [S. Veprek, J. Vac. Sci. Technol. A 1999, 17, 2401–2420]; a large volume fraction of grain boundaries provides ductility through grain boundary sliding and nano-cracking along grain/matrix interfaces. Application of AgNp ensures important improvement of electrical contact material properties.

S&T objectives of the Project are presented below. The Project goals were attained through the solution of the following scientific and technological problems (Project objectives):
-Development and pilot production of Silver based crystalline nanoparticles biosynthesis using Mexican plants. To ensure the safe and clean conditions for their further processing, methods for production of nanoparticles dispersions were also developed. Modelling and detailed study of novel nanoparticles (physical, chemical properties, biochemical analysis, size, surface energy, viscosity, etc.) and development of a metrological approach allowing reliable quality control of nanoparticles production process was be realized in the frame of the Project. A few litres of nanoparticles dispersions of various types were be available for further deposition and sintering processing;
- Development of methods for deposition of implant coatings containing Ag based nanoparticles:
Electrophoretic process combined with low temperature sintering and plasma spraying ensures desired Ag Np concentration in the Ti, TiO2 and Hydroxyapatite matrix. The members of the Consortium has important background in the development of such type of nanomaterial processing: 2PS in plasma spraying, TESSONICS in electrophoretic process;

-Characterization and in-vitro evaluation of the developed coatings:
Nano-structure: investigation of nanostructure by High Resolution SEM and TEM
(particle dispersion, coating structure), Ti, TiO2 and Hydroxyapatite nanostructured coating by use of FIB machining, phase investigation, nanograins study (stiffness and hardness) by Scanning Probe Microscopy (SPM), etc.;
Corrosion properties determination by electrochemical measurements. The measurement of corrosion potentials are to be performed in accordance with ASTM (American Society for Testing and Materials) methods G69-97 with environment at 25 °C. All electrochemical potentials are to be referenced to a saturated calomel electrode (SCE). Electrochemical Impedance Spectroscopy (EIS) is going to be used to measure corrosion-resistance coatings performance;
In vitro study consists of:
i) Cytotoxicity analysis which was to be conducted using material samples on human fibroblast cultures, microscpic analysis of tissue cultures was be performed after incubation with material samples;
ii) Antibacterial activity which was to be conducted using material samples on standardized bacterial cultures, evaluation of the bacterial growth inhibition (antibacterial potential) of tested materials was be done as well;
iii) Infection resistance tested (Potential to prevent bacterial biofilm formation responsible for persistence of infection and resistance to antibiotics were determined), and
iv) Osteointegration potential evaluation ( Incubation of the tested osteointegrating material samples with rat osteoblasts cultures). SEM analysis on adhesion of rat osteoblasts to tested materials was performed.

-Development and pilot production of Silver based nanostructured composites for electrical contacts: Ag-SnO (instead of hazardous Ag/CdO composite) and Ag-nanoMoS2 (sliding electrical contacts):
Development of Ag based nanostructured composites manufacturing based on Mechanical Alloying and Powder Metallurgy production routes. To ensure the safe and clean conditions for their further processing methods of mechanical alloying and manufacturing of nanoparticles dispersions and micro-sized granules were also developed. Modeling and detailed study of novel composites (physical, mechanical properties, tribology parameters and electrical characteristics) and development of a metrological approach allowing reliable quality control of composites production process was realized in the frame of the Project. Investigation of composites nanostructure by High Resolution SEM and TEM was performed;

-Pilot production, trials and impact demonstration of developed Ag Np modified implants and Ag based nanostructured composites in accordance with End-users industrial tasks. Two main groups representing typical end-users components are:
1st Group - TiO2 and Hydroxyapatite Ca10(PO4)6(OH)2) coated implants which are widely used in orthopaedic surgery because of their good biocompatibility related to the osteoconductive properties of calcium phosphate coating;
2nd Group – Ag-SnO, AgZnO and AgRe contacts for electrical systems; these composites combine high resistance to welding and to electric arch erosion of the refractory phases with the high electric and thermal conductivities;

-Realization of specific measures for results exploitation and dissemination: patents, publications, training and education, evaluation of the cost effectiveness.
Project Results:
The Nanomining project generated following results:
1) Mechanically Activated Thermal Oxidation (MATO) Technology and MATO machine for Jarosite Treatment:
A pilot fluidized-bed oxidation reactor (developed and installed by INOP-figure 3) is to carry out the pilot experiments under the operating conditions of interest and to make possible observation and recording the process parameters during the runs.
Tamuse Co and University of Juarez developed the new design of microwave oxidation oven based on the experimental results with the jarosite oxidation in laboratory microwave oven.
The first trials of the rotary microwave MATO technology reactor prototype were made to define the temperature – time relationship for jarosite powder heating.
The optimization of technology parameters of the pilot MATO process realised in fluidized bed reactor was performed to achieve the stable material flow characteristics in the fluidized bed column and collection of processed product in backhouse dust collection and cyclone solid collection canisters. Analysis of the flow diagrams of the pilot fluidized bed reactor shows that the turbulent fluidized regime of circulation is more favorable for the jarosite particles of the sizes 3-5 μm, that allows to diminish the time of Jarosite milling before the thermal oxidation. It is defined the time of oxidation of the particles of 3-5 μm size is about 15 min. The Zn reduction MAREC (Mechanical Activation-Thermal Reduction) process is developed and elaborated for Zn containing waste of Boleslaw Plant, Poland. The new furnace design was developed by INOP for reduction of Zn and Pb, and collection of the product in protective atmosphere (figure 4). Application of magnetic field allows to create the high porous fluidized bed similar to those of fluidized bed reactor.
The results of pilot fluidized bed reactor trials show that the specific Jarosite conversion rate in the INOP pilot reactor is higher as compares with previous suggestion. The industrial conversion rate depends on the mass of fluidized bed column. An increase of the fluidized bed column height in the pilot reactor up to 1000 mm results in increase of specific conversion rate up to 80 kg/h. The second result obtained at pilot fluidized bed reactor trials is definition of minimal grain size of Jarosite powder. In the case of processing of jarosite with particle size of 3-5 μm the total labor costs per year (milling+thermal oxidation) will decrease by 20 %, maintenance costs – by 10 %, energy consumption – by 30 % . Thus, the total operating costs are diminished up to 24.89 k€/year.

The MATO machine consists of two basic parts; (1) The Jet Mill for jarosite grinding and milling, and (2) The Rotary Oven where electrical heaters are combined with microwave energy to oxidase the reduced size jarosite.
The jarosite used for the development of the MATO machine came from the Peňoles refinery in Torreon, Mexico, as delivered, jarosite comes in a mud-like state that requires drying before it is processed in the jet mill. As jarosite is dried, it turns into solid chunks that may be too large to enter the jet mill chamber directly; therefore a rough grinder was built of aluminum into the jet mill for pre-milling. The grinding takes place right before the input to the milling chamber and is powered by a Baldor 0.13 HP electrical DC motor. The particle size of the jarosite as it comes out of the grinding or premilling averages 3.4 µm. After the grinding process, the jarosite is pulled into the jet mill chamber by a venturi valve which creates a vacuum between the grinding output and the jet mill chamber.
Jet milling
The jet mill utilizes fluid energy in the form of compressed air to micronize the jarosite. The milling take place in a circular 8-inch stainless steel chamber where high pressure air (70-90 psi) is forced through a series of jet nozzles which axis is tangential to the circumference of a smaller, imaginary concentric circle producing a 7,000-10,000 rpm velocity inside the milling chamber.
During the operation, these jets generate high speed vortex inside the chamber and the materials feed through a separate venturi system from the grinder, which creates a partial vacuum to suck the material into this high velocity vortex. Strong velocity gradients near the jet cause the suspended jarosite particles to collide with each other and reduce themselves by attrition and collision.
The micronized jarosite exits through an outlet at the center of the chamber from the top via stainless steel tubing and draws the micronized jarosite with it to a two-cyclone collector system made of stainless steel. Heavier oversized particles are held in the milling chamber by centrifugal force, until micronized to desired size.
Rotary oven
The oxidation rotary oven is made up of three cylinders where an inner most cylinder houses the reduced-size jarosite for processing using conventional and microwave energy
for heating. Ceramic electrical heaters capable of reaching temperature of 600 °C, surround a second cylinder that is very close to the inner most cylinder in order to provide the initial conventional heat and four magnetrons located in the back cover to provide microwave energy. Experimentation at the UACJ lab and with the MATO oven, has led to determine that jarosite is best oxidized when heated to about 220 °C with the ceramic heaters followed by 5-15 minutes of microwave energy depending on sample quantity. The rotation mechanism is made up of a series of specially designed bearing system that allows the inner most cylinder to rotate while the other two cylinder to remind in a fixed position.
In order to conserve energy, the second cylinder is filled with ceramic insulation fabric providing safe operation to the MATO operator.
The rotation is done by a 3 hp 440 V electrical motor and a 40/1 transmission which can continue rotation for the emptying operation which is done by two air cylinders located at the bottom of the steel structure. The jarosite loading is done in the front cover where an automated door is operated by an air cylinder and microwave heating energy is applied by the use of four magnetrons located in the opposite cover.
The magnetron antenna is inserted into the rear cover of the inner most tank when it is time for microwave energy application in other to avoid heat from the electrical heater to be transferred to the magnetrons while traditional heating is taking place. The magnetrons
are mounted on sliding mechanisms that can be individually selected or coupled for the time selected by the desired programming recipe depending on the sample quantity and the process parameters chosen.
Controls
The MATO machine includes four small cabinets for different controls; (1) Logic control, (2) Temperature control and (3) Magnetron electronics. The logic control cabinet houses a Micrologix 1400 PLC for the overall automation of the MATO machine, where different recipes can be programmed for different parameters such as electrical heating temperature, heat application timing, microwave energy application timing and the number of magnetrons to use at a time or in combination. The temperature control cabinet includes a Watlow controller and related sensors and electronics and the Magnetron electronics cabinet include four high voltage capacitors and transformers and wiring.
Software
The MATO programming was done using the RSLogix 5000 ladder logic programming software by Allen Bradley. RSLogix 5000 offers an easy-to- use IEC61131-3 compliant interface, symbolic programming with structures and arrays and a comprehensive instruction set that serves many types of applications. It provides ladder logic, structured text, function block diagram and sequential function chart editors for program development as well as support for the S88 equipment phase state model for batch and machine control applications.
For the MATO machine, different recipes were written to vary operational parameters depending on jarosite sample available for the different runs.
Milling results
Milling tests of MATO’s reactor were performed using Mexican Jarosite, Slag (from MAREC technology for Zinc recovery) and Mexican Tails. In all cases, results showed that the MATO reactor is able to reduce the particle size up to the required levels for silver leaching (Jarosite case) and slag and tails processing. Figure 8 shows examples of the Jarosite pre-milling results. As can be observed, particles are smaller than 37 μm, the value required for high efficiency silver recovery (approx. 93 %).
Mexican slag from the MAREC project for Zinc recovery was also milled using the MATO reactor. Particles in the range of ~1μm to 250 μm are observed after milling. The slag in the as received condition show very large particles (~2000 μm).
The tail in the as received condition shows agglomerates of approximately 3 cm. After the pre-milling operation with the MATO reactor particle size is reduced to 100 μm or less.
Jet Mill conditions were 60 PSI in the chamber and 90 PSI in the venturi valve. The average Jarosite particle size after pre-milling is 3.4 μm. Without pre-milling Jarosite average particle size can be reduced to 1.2 μm (first tank) and 0.77 μm (second tank) after 10 min. If pre-milling and 5 minutes of Jet Milling are applied an average particle size of 1.38 μm is obtained. This value is similar to the values obtained after 10 minutes without pre-milling in tank 1.
Thermal oxidation results
Several second stage trials of the MATO reactor using large Jarosite batches took place during the 24-36 months period. These trials were performed with the objective to determine the MATO reactor optimal parameters using large Jarosite batches.
Batches of 30 kg were used and the MATO reactor was heated up to 250 °C using the MATO resistances. The Peñoles Jarosite was milled using the Jet Mill to obtain particles in the range of ~1μm to 250 μm. Heating up time was 125 minutes. After this time, MATO’s magnetrons start operating (alternating 5 minutes each per cycle) and Jarosite samples were taken each 10 minutes up to complete 225 minutes since start up. Rotary movement was kept during the complete trial. Jarosite temperature was recorded at the MATO’s walls and the energy consumption was measured using a (Ohio Semitronics A210 - Multi-function Power Meter).
Additionally, trials using 14 kg Jarosite batches were performed. In these tests MATO’s reactor operation was modified to reduce the magnetrons temperature and improve their performance (magnetrons during 30 kg were heated by conduction of the heat generated by the heating elements). Trial was performed as follows:
1. Reactor was heated up to 250 °C using its heating resistances and then resistances were turn off. Rotary movement was kept. Magnetrons were insulated.
2. Magnetrons were turned on during 30 minutes (at 10 minutes cycles by alternating power each magnetrons for 5 minutes each). Samples were taken each 10 minutes.
Jarosite characterization (before and after trials)
The coloration change (typical of the Jarosite phase transformation) of the processed samples is easily observed.
Silver and Zinc content of the Jarosite before and after trials was verified using Atomic Absorption. Results are shown in Table 1. As can be observed, Silver content is similar to the previously reported values. Zinc amount is probably decreasing by evaporation during the Jarosite MATO’s processing.
X-Ray diffraction analyses were performed on the MATO’s samples and results were compared with conventional processed samples. Intensity differences of the Fe2O3, ZnFe2O4 and Fe3O4 main peaks were observed. The effect of these differences during silver leaching is under investigation.

2) Ag Nanoparticles bio-synthesis using dessert plant
Nanobiotechnology deals with the application of biological systems for the fabrication of nobel functional material such as nanoparticles. Biosynthetic procedures can use either microbial cells or plant extract for nanoparticles production. Biosynthesis of nanoparticles is an attractive recent technology to the great variety of nanoparticles synthesis methods and recently, nanoparticles has going in a commercial exploration stage. Gold and silver nanoparticles are currently under intensive study for applications in optoelectronic devices, ultra sensitive chemical and biological sensors, as catalysts and many other biological uses.
While microorganisms such as algi, bacteria, actinomycetes, and fungi continue to be investigated in metal nanoparticle synthesis, the employ of parts of whole plants in analogous nanoparticle synthesis methodologies is an exciting possibility that is relatively unexplored and underexploited. Here, we chose a cacti extract plant known in México as nopal that belongs to the genus Opuntia, which belongs to the 1500 species of cactus and is mainly distributed in south-western United States and northern Mexico. For a long time, Mexican populations have used the leaves of prickly pear cacti (nopal) for their medicinal benefits. Possessing crassulacean acid metabolism, this genus of cacti is reported to be four to five times more efficient than most grasses in converting the sun’s energy, water and minerals to dry organic matter [Garcia de Cortazar V, Nobel PS (1991) Prediction and measurement of high annual productivity of Opuntia ficus indica. Agr for Meteorol 56: 261–272]. We demonstrated that nopal cladodes extracts are able to reduce Ag ions.
The new biosynthesis process was developed and optimized to reach desired nanoparticles shape, size distribution and structure for successful application in modification of hydroxyapatite implant coatings.
The basic mechanism in all cases involves the accumulation of nanoparticles after the reduction of metal ions. Definitely this reduction process is mediated by some reducing agents or may involve some enzymes that are bound to the cell wall (figure 5). The reactor developed by CIQA is equipped with temperature control and agitation. A glass thermometer was inserted inside the reactor to measured reaction temperature. The kinetics of the formation of silver nanoparticles using different concentration AgNO3 was studied. A change in absorbance at 420 nm was observed in all the concentration used, but this change increase rapidly as the concentration of the metal salt in reaction is higher. At the concentration of 1x10-1.5 M the silver nanoparticles are formed almost instantly. In all the assayed concentrations the silver nanoparticles showed a spherical shape (figure 6.). However, as the concentration of the metal salt increase, the nanoparticles have a tendency to agglomerate due likely to the simultaneous formation of great number of nucleus that interfere in the growth of the nanoparticles or to the limitations of stabilizing agent to cap the nanoparticles [E. C. Njagi, H. Huang, L. Stafford, H. Genuino, H. M. Galindo, J. B. Collins, G.E. Hoag, and S. L. Suib. Langmuir 2011, 27(1), 264–271].
Fractionations of nopal cladodes extract by micro-filtration and ultrafiltration: In order to study the nature of the bio-molecules that influence on formation of the metallic nanostructures and the possible participation of these compounds on the antimicrobial activity nopal cladodesos extracts were fractionated by applying techniques of dialysis, micro and ultra filtration with membranes of hole fiber with different size pore and molecular weight cut-off (0,1 µm, 0.2 µm, 5x105, 1x105, 5x104, 3x104, 1x104 and 3x103. Each of the obtained fractions was characterized and evaluated in order to determinate the capacity for the formation of Ag nanostructures. Ultrafiltration system using a membrane with a molecular weight (MW) cutoff of 1x103 ( A/G Technology Corporation, Needharm, MA, USA) , and after that was lyophilized for two days.
Uv-visible spectra of nopal extract and the sample after ultrafiltartion through a hollow membrane with a molecular weight (MW) cut off at 1x103. The spectra were quite similar with maximal absorption peaks at 225 nm, 272 nm and 336 nm that could be related with the presence of certain type of flavanoids. The amount of pectin was reduced from 16 % in the complete nopal extract to 2 % in the ultrafiltrated fraction.
To probe if the compounds present in permeate, after been passed through the hollow membrane could had the ability to reduce silver ion, we carried out a reaction using the same reaction conditions reported previously. We found that this fraction was capable to produce silver nanoparticles. Apparently, they are quite similar to those obtained with nopal extract without filtration.
The process was scaled up from a 600 mL reactor to 2 liters reactor in order to increase the silver content in the AgNp and improve the efficiency of the reaction catalyzed by nopal extracts. The rate of AgNO3 conversion to AgNp is directly proportional to the amount of nopal extract used in reaction. We tested up to 2.6 g and seem that still is room to increase the nopal extract content in order to improve the yield of the reaction. The UV-vis spectra indicate that the amount of nopal extract used in the AgNps synthesis apparently do not affect the size and shape of these nanostructures. The maximal absorption around 410 nm, clearly reveal the presence of silver nanoparticles which is due to the excitation of surface plasmons. TEM images analysis corroborate these results, the morphology and shape of nanoparticles are spherical in shape and uniformly distributed without significant agglomeration.

Conclusions:

• Green synthetic route to obtain silver nanoparticles (AgNp) using nopal extracts as reducing and stabilizer agent ions was developed (size in the range 2-24 nm);
• An eco-friendly and low cost protocol for biosynthesis of silver nanoparticles using nopal extracts has been demonstrated and scaled up to a 2 L volume;
• The economic estimation of AgNp cost (40 USD/g) produced by biosynthesis gives relatively low value for mass production of this material.

3) Plasma Spraying of HAP coatings containing Ag micro - AgNps, in vitro and in vivo test

Plasma Spraying is the most widely applied method to deposit HA coating onto titanium alloy prostheses (90 % of implant manufacturers use this type of coating deposition ). The method consists of injection of HA particles into a high temperature (>10 000 K) plasma jet. Intensive HA particles heating leads to dehydration and decomposition of HA. 2PS developed original spraying technology for HA coating deposition. HA coating were deposited on the surface of Ti-alloy disk samples and cylindrical samples by 2PS. These samples were used in further research of AgNp sedimentation on the HA coating surface, coating characterization and testing and in vitro and in vivo tests. Typical image of HA spraying process and Ti-alloy disk samples with HA coating are present in figure 7.
New spraying technology of deposition of HA coatings containing Ag micro- nanoparticles requires on-line monitoring of sparing process parameters both at stage of the process development and optimization and at stage of mass production to ensure process stability and coating quality. The diagnostic method and equipment were developed by the Project partner IfU. The main idea consists on the illumination of passing particles by a pulsed infrared laser. The reflected part of the pulsed laser radiation signalized the passage of the particle through the measurement window. The time of flight is an inverted signal to the particle velocity. During the time of passage the emitted thermal radiation of the particle is captured by two fast detectors with different spectral ranges. The ratio of the two emission signals results in a fast temperature measurement. Therefore a single particle statistics for velocity and temperature is possible. This information is used to benchmark the quality of the particle beam.
As a result of process optimization the influence of the main spraying parameters on the particles temperature and velocity was studied. As a result, the range of spraying parameters required to reach desired coating quality was defined.
One of the most promising way for modification of HA coatings with AgNps is their post treatment by sedimentation process. The sedimentation process was developed in the frame of the Project by INOP (figure 8). The laboratory set-up was used for the development of AgNp sedimentation process. It consists of chemical flask that is placed on rotation unit providing maximum rotation speed 600 rpm. The disk samples were suspended with the help of stand-alone holder inside of the flask. The time of samples treatment was varied from 24 to 60 hours. The sedimentation is registered on variation of AgNp concentration in a solution that is reflected in a spectrum as falling of intensity of an appropriating absorption peak. Hielscher Ultrasonic Homogenizers (HUH) with 400 W power was applied to avoid AgNp agglomeration and to reach more uniform distribution of AgNp on HA surface. SEM study of AgNps on the surface of HA plasma sprayed coating were carried out. The concentration of Ag on the surface of HA can be varied in wide range (1-19 wt%) by regulation of sedimentation parameters.
The Ag-nanoparticle containing liquids were investigated by surface plasmon resonance measurements. It was done in order to develop approach for monitoring of nanoparticle agglomeration process that is important for final modified coating properties. The absorbance of surface Plasmon resonance is very well to be seen in all samples at 400 nm …424 nm. The liquids after sedimentation process demonstrate a progressive conglomeration that could limit application time of initial AgNps containing liquids and should be control during the sedimentation process realization. The results of study show that initial liquids show high stability over two months.
The engineering scale-up measures were performed by 2PS (plasma spraying), IfU (diagnostic system integration) and INOP (sedimentation process). Elaboration of engineering approach to scale-up of existing laboratory equipment was performed in parallel with study of features of coating technologies in the industrial environment. At the first step 2PS (like and industrial end-user) decided to do HAP+AgNp coating on a hip cups (figure 9) and transfer in the future new technology on other implants manufactured by 2PS. In fact, the geometry of hip cups is relatively simple (half sphere) and the coating can be realized in good condition with regard to the kinematics of the moving piece in front of the plasma torch.
For successful implementation of new production technology 2PS has realized a modification of spraying equipment (powder feeding unit and nozzle) to reach stable flow of HA+Ag mixture in production process.
Powder mixture and coating should correspond to relevant European and American progress in this area. 2PS created a dossier of design for this new coating through quality (ISO and FdA) and will do all the conformity checks in collaboration with organisms accredited COFRAC.
As a result of process optimization optimal parameters for spraying of HA+AgNp and HA+Agμ mixtures was defined for CIMAV and 2PS technology correspondingly.
The developed coating technologies were successfully transferred from laboratory disk samples (used for coating mechanical and corrosion properties characterization and in vitro tests) to real implants (cylindrical implants for rabbits used for in vivo tests and hip cups). The analysis of industrial work environment was performed by 2PS:
-Customers: About 30 prostheses companies in EU: Center Pulse, Stryker, DePuy, Zimmer, Biomet and Smith & Nephew;
-Potential market: 200,000 – France; 200,000 – Germany; 100,000 – UK; 80,000 – Italy; 100,000 - other EU countries;
-The standard coating cost: 45-55 € for cup (single layer); 50-60 € for cup (double layer);
-Investment in new equipment: powder distributor ~40 K€; diagnostic system ~20-25 K€); sedimentation equipment ~6-8 K€;
-Taking into account all above mentioned factors, the increase of new coating cost is expected near 10-20 %.
160 disk samples were fabricated from TiAl6V alloy 155 samples were processed: coated with various types of HAP coating containing AgNp. These samples were characterized by SEM/EDS. 130 the most suitable samples were in vitro studied. The most promising types of coating containing AgNp were chosen for further processing: Plasma sprayed coatings deposited using mixture of AgNp produced by biosynthesis from dessert plants; sedimentation of AgNp on the surface of commercial HAP.
90 cylindrical samples were fabricated from TiAl6V alloy. 89 samples were processed: coated with the most promising types of HAP coating containing AgNp. These samples were characterized by SEM/EDS, release if Ag ions and wettability were studied. 78 the most suitable samples were transferred for in vivo tests.
Results of in-vitro tests show that tested samples inhibit the proliferation of fibroblasts in comparison to the control – HA-only samples. The inhibition was comparable between the samples. Results show consistently that Ag coated samples promoted osteoblast growth in first 12 hours. In further assessments growth was inhibited significantly in comparison to control HA-only samples. Cytotoxicity analysis and SEM analysis of tissue cultures after incubation. Implants covered by HAP+Ag3%(INOP-commercial nanoparticles) and HAP+Ag3%(CIMAV-nanoparticles produced by biosynthesis) were incubated for 1, 2, 3 and 4 weeks in culture medium in incubator (37 ºC, 5 % CO2). The cytotoxicity of CM was measured on (Human osteoblast (CRL 11372) cell line. It was shown that modified coatings both HA+AgNPs (INOP) and HA+AgNPs (CIMAV) are non-toxic for osteoblast growth and proliferation.
Antimicrobial activity of initial HAP, HAP+AgNp(INOP) and HAP+AgNp(CIMAV) was evaluated against the ATCC 35984 Staphylococcus epidermidis (LGC Standards) strain. Anti-bacterial activity tests were made to show significant antimicrobial properties of the implant coatings containing silver nanoparticles. The presence results of silver on hydroxyapatite surface substantially reduces the number of living S. epidermidis bacteria.
The difficulties in the interpretation and repeatability of in-vitro test result and difference with in vivo positive test results (see paragraph below) could be probably caused by the situation that contact between the surface containing AgNp is weak in in vitro tests and during in vivo tests there is direct contact with the cells and therefore these tests (in vivo) are much more better and reflects reality.
The performed in vivo studies are realized in order to compare the properties of commercial samples (used in medical practice) to the produced ones covered by AgNp. The following tests were performed:
-Histology, immunohistochemistry of the surrounding bone in aseptic and septic conditions
-Systemic toxicity – organ samples (lungs, liver).
It was decided to make tests on 36 rabbits choosing 4 types of coatings preselected to animal tests: 1xHA only (2PS), 3 x HA+Ag (2PS, CIMAV).
The operation was made in aseptic and septic conditions, series of 12 laboratory rabbits. The implanted animals were observed within 2 months. Animal cylindrical implants with new HA+AgNps coating was used for surgical operation on implantation.
After two months post surgery all rabbits were sacrificed. Firstly the blood was collected. Entire femoral trochlea in which the implant had been inserted was removed from each rabbit using a bone saw and fixed in buffered paraformaldehyde solution pH 7.4. A kidney and liver were also collected and fixed in formalin for further analysis. All blood samples were centrifuged (with 3000 g for 15 min.) and plasma was divided into Eppendorf tubes. The main results of observation are the following:
-No major complications of the postoperative wound
-All wounds after contaminated septic implantations healed without complications
-In all cases implants were surrounded with the new bone
-Full mechanical stability was achieved – positive osteintegration
There were no complications after implantation and positive osteintegration was observed.
Histopathological examination of organs show:
-Kidney (from a rabbits with a samples Ti6Al4V+HA): acute renal failure, Glomerulonephritis has immunological background, created by the presence of chronic inflammatory processes taking place in the body of rabbit
-Kidney (rabbits with samples of Ti6Al4V+HA+nAg)- acute renal failure
-Liver (from a rabbits with a samples of Ti6Al4V+HA)- necrosis of individual hepatocytes, necrosis of individual hepatocytes, which have disintegrated cell nuclei and hydropic degeneration of parenchymal necrosis and small clots of liver cells
-Liver (rabbist with samples of Ti6Al4V+HA+nAg)- during liver histopathology were found interstitial hepatitisagainst parasitic- presence of protozoa, and degeneration and congestion of the liver.

Conclusions:

-In the frame of the Project the following technologies for deposition of antibacterial coatings were developed and evaluated. All methods give promising results for creation of antibacterial HAP coatings on Ti-alloy surface of implants:
1. Deposition of HAP coating under optimum conditions and their post treatment with AgNp by sedimentation of AgNp from liquids
2. Deposition of coatings from pre-mixed HAP powder and Ag micro-particles
3. Deposition of HAP+AgNp from pre-mixed HAP powder and pre-mixed AgNp (CIMAV and CIQA)
-A new method and equipment for particle jet diagnostic (velocity and temperatures) in plasma spraying processes was developed and tested
-Real HA+Ag Plasma Spraying Process was studied and optimised
-Liquids containing AgNp before and after sedimentation process were studied in order to define the agglomeration problems and optimise process parameters
-Evaluation of economic feasibility of new developed coating technologies and diagnostic equipment and their market potential were evaluated
-Wide range of in vitro tests was carried out: proliferation of fibroblasts, cytotoxicity and antimicrobial properties. Antibacterial activity tests show significant antimicrobial properties of the implant coatings containing silver nanoparticles produced by biosynthesis
-In vivo tests were done on rabbits. There was no pain observed during their walking. Introduced Ag and HA bone implants did not pose any harmful influence on liver and kidneys in experimental rabbits. Described morphological lesions observed in kidneys and in liver occurred under the influence of multiple environmental and culturing factors. Ag and HA implants introduced to bones of rabbits caused local stimulation of new bone tissue development. Examined Ag and HA implants did not cause the development of inflammatory process or local immune reaction within the bone tissue.

4) Electrical contacts based on Ag-based nanocomposites
Tests carried out within the NANOMINING project included technology for 3 nanocomposite contact materials of the following sorts: AgRe, AgSnO2Bi2O3 and AgZnO produced in the form of wires and also bimetallic and solid contact rivets. These materials have not been made so far on the production scale, neither by national, nor other world known contact materials producers. Idea of new materials is to produce nanocomposite consisting of silver matrix with uniformly distributed oxide nanoparticles of the following elements: tin, bismuth, zinc and metallic rhenium. That phase of high dispersion and homogeneity causes strengthening of produced nanocomposite characterised by high resistance to electrical arc erosion. The resistance to electrical arc erosion can be even several times higher than for classic contact materials (figure 10). New developed technology makes also possible to produce nanocomposites of significantly higher oxides content, i.e. up to 15 wt. % as compared to AgMeO classic composite materials. As a result of these favourable properties new materials will be significantly cheaper in the exploitation and they will enable to extend range of working conditions for electrical appliances equipped with new generation contacts. Based on the results of contact life of solar relays with new electrical contacts containing tin and bismuth oxides, it can be predicted that their contact life will be at least 30 % higher than with the classic composites. The materials will be applied in different kind of electrical switches, such as: relays, contactors where they will replace silver-based classic contact materials used so far. Application of new-developed contact materials in electrical connectors will also cause saving of silver consumption resulting from their beneficial electrical properties.
The developed technology is based on modern production processes of silver powders and its alloys and also their processing using i.e. plastic consolidation during extrusion on the hydrostatic presses or presses working in the KoBo System. The technology was verified on the basis of pilot scale on industrial equipment and confirmed by the achieved results.
Developed materials will be applied in electrical engineering – mainly for production of wide range of low-voltage electrical apparatus (relays, contactors and circuit-breakers). They will replace in these apparatus contacts of materials unfriendly for environmental that still are: AgCdO (10-15) wt.% and AgNi (10-20)wt. % and also classic composite materials i.e. AgSnO2Bi2O3.
Technology for production of AgRe nanocomposite
The method for production of this kind of material bases on the mechanical synthesis of silver and rhenium based powders mixture. Powders particles being charge materials should be characterized by irregular shape and their grain-size median should be at the level from 0,05 to 150 µm for silver and from 0,05 to 10 µm for rhenium. These powders of particular weight content which according to the patent is 0,1-20 wt.% of rhenium (research works within the project were mainly focused on material containing 10 wt. % of rhenium) and the rest silver, are subjected to highenergetic milling operation for min. 30 hours. The obtained in such way nanocomposite powder is consolidated (with application of isostatic press) to the form of compacts of i.e. dia. 50mm and length 150mm. The compacts are sintered favourably in the vacuum (or hydrogen) at 1,33 Pa (10-1Tr) at least and temperature within the range of 700 °-850 °C, for time not less than 3 hours. The semi-product is processed during extrusion into wire compact with application of KoBo hydraulic press or hydrostatic press. The extrusion operation should be carried out – favourably on hot below the temperature of 3000 °C at extrusion coefficient >80, for compact diameter of 4,0 mm. Further processing of the compact material into wires, bimetallic and solid contact rivets is cold drawing of the compact with reduction unit of 10-20 % to dimensions enabling their processing into solid and bimetallic contact rivets without any losses. Simultaneously, their production process should be conducted in such conditions which could maintain nanostructure in the processed material.
Technology for production of AgSnO2Bi2O3 and AgZnO nanocomposites
The results of finished studies of two oxide nanocomposite materials made possible to develop technology, which can be realized in two different methods basing on:
1. Mechanical synthesis of silver based powders with tin, bismuth and zinc oxides – in case of AgZnO nanocomposite. The nanopowders obtained in this process are subjected to the consolidation process, sintering and plastic working of compacts during the hot extrusion with application of hydrostatic press or KoBo hydraulic press. Using that equipment relatively high processing level can be obtained which is described by coefficient favourably at the level > 120.
2. Internal oxidation of AgSnBi and AgZn powder alloys, and obtained metal-ceramic composite powders are processed into nanocomposite contact materials with obligatory plastic consolidation in the hydrostatic extrusion process or extrusion on the KoBo press, that ensure coefficient favourably at the level >120.
The charge materials for these two methods of production are: powder of pure silver and its AgSnBi and AgZn alloys of physic-technological parameters similar to Ag powder used for production of AgRe nanocomposite. These powders are produced in the water atomization process. In case of tin, bismuth and zinc oxides their granulation can be below 1µm. In case of chemical purity all charge raw materials used in the process should be characterized by purity of min.99,9 wt.% of main component.
In case of method based on the mechanical synthesis of silver based powders with oxides, the process is carried out in the highenergetic ball mill. During its realization proper technical and technological parameters should be maintained, i.e.: ratio of milled powders weight to balls weight, determined value of critical drum speed, milling medium dimensions and material sort of which they are produced and others. These conditions should ensure production of silver-metal oxides production susceptible for further processing on contact materials in the form of wires, bimetallic and solid contact rivets. This processing includes consolidation of the nanopowders to the form of compacts which is conducted on the isostatic press and then it is subjected to sintering, hot consolidation. The next step is plastic consolidation in the extrusion process which in the final phase of this operation includes processing on the hydrostatic or hydraulic press working in KoBo system. That stage of the processing guarantees relatively high level of plastic deformation of processed material determined by coefficient at the level of min. 120. The final product of that operation is a wire compact of i.e. dia. 3.9 mm characterized by nano type of the microstructure. Oxides nanoparticles of high dispersion level evenly distributed in silver matrix which crystallines size is below 200 nm. Contact rivets produced of that material are characterized by relatively high resistance to electrical arc erosion what has also effect on the high contact life of electrical apparatus containing that kind of electrical contacts. That method is technologically more favourable for production of nanocomposites of higher oxides content what in consequence leads to savings of silver which is expensive raw material.
The method basing on the internal oxidation of AgSnBi and AgZn powder alloys requires internal oxidation of metals dissolved in silver to the form of SnO , Bi2O3 and ZnO oxides. The operation of oxidation includes compacts produced during the isostatic consolidation of powder alloys. There is also considered modification of that stage of technological process and its replacement by powder alloys oxidation (before their consolidation on the isostatic press) carried out in the specially constructed reactors. That process would be shorter and cheaper. However, it requires suitable tests. It is planned to take up them within the new research project. The oxidized compacts are subjected to further processing using the method which is similar to processing of the compacts produced of nanocomposite powders obtained during the mechanical synthesis. Figure 6.44 presents scheme of oxide nanocomposites production and picture of technological line for nanocomposites production.
Technical and technological conditions for production process of three sorts of nanocomposite contact materials: AgRe, AgSnO2B2O3 and AgZnO
General description of the technology for production of three above-mentioned sorts of nanocomposite contact materials is presented in the point 1-2 of this report. Point no. 3. presents technical and technological conditions for the production process of the above-mentioned materials with special consideration of required equipment (detailed description of the technological line adopted for production of that sort of products is presented) and basic technological parameters for particular operations are given, i.e.: sorts of the charge materials, characteristic parameters for production of silver and rhenium based powders, Ag powder alloys with tin, bismuth, zinc and also characterisation of the following oxides: tin, bismuth and zinc, their further processing stages up to obtaining ready products – wires, solid and bimetallic contact rivets.

Production of nanocomposite, especially bimetallic, contact rivets was carried out in the production conditions similar to these in which currently contacts from AgSnO2Bi2O3 and AgNi10 composite materials are produced (in the future AgRe nanocomposite will be its substitute). The difference is only that AgSnO2Bi2O3 nanocomposite was extruded with application of hydrostatic press (one-hole, compact dia. 3,9 mm) and AgRe10 on the hydraulic KoBo press (one-hole to dia. 4 – 2,5 mm). For so far produced composite materials cost of electric energy in the whole production cost of bimetallic contact rivets is at the level:
10,5 % for AgSnO2Bi2O3
11 % for AgNi10
It is estimated that energy consumption at nanocomposite contact rivets production should not be significantly higher because hydrostatic extrusion with application of hydraulic KoBo press makes possible to produce compact of relatively low dia. at the level of 3-4 mm. Its further processing to the wire for contact rivets production doesn’t require high costs which are lower than for plastic working process of the composite materials.

During conducted tests connected with development of technology for production concerning three sorts of contact materials most researches of physical and mechanical parameters of produced raw-materials, semi-products and final products were carried out in research laboratories of the Institute of Non-Ferrous Metals. They mostly concerned: analysis of the chemical composition, tests of physical and technological properties of the metal powders and metal oxides, tests of mechanical properties of semi-products and final products, phase analysis, X-ray microanalysis, identification of nanostructure with application of transmission electron microscope, electrical arc resistance and contact resistance of final electrical contacts and others. Some studies were also made outside the Institute, mainly following tests: contact life of electrical relays equipped with bimetallic contact rivets – of AgSnO2Bi2O3 nanocomposite and friction factor of ready contact rivets.

Fabrication of the AgSnO2Bi2O3 nanocomposite by means of internal oxidation technology and plastic consolidation accomplished in the processes of hydrostatic extrusion and drawing

The starting material for fabrication of the contact nanocomposite material was a powder obtained from the AgSn7,5Bi0,4 alloy by water atomization conducted at the elevated pressure of about 180 bar. The size of crystallites of this alloy was at the level of < 100 nm. The technology employed was similar to the used at present with such a difference that the extrusion process was performed by means of hydrostatic press. The compacts 50 mm in diameter (see below Figure) were extruded into a wire about 4 mm in diameter at the extrusion ratio close to 156 (the process was conducted at the temperature of 600 °C). The wires obtained by hydrostatic extrusion were subjected to microstructure examination by means of the optical microscope, scanning electron microscope, and the transmission electron microscope.
Production of AgRe1 nanocomposite contact material in the form of wires and bimetallic contact rivets
Considering economic aspects connected with relatively high price of rhenium (current price of this metal is 3100 EUR/kg) and results of tribological tests a decision of testing the production technology of that group of nanocomposites decreasing their rhenium content from 10 wt.% to 1,0 %.0 was taken. The products (contact rivets and wires) with that rhenium content and characterized by high electrical properties (resistance to electrical arc erosion and high contact life of electrical apparatus equipped with that kind of contacts) could be more easily accepted by the market compared to material containing 10 % of this element. For information, it should be explained that invention project (patent application) of our Institute, which concerns that kind of material and method of its production predicts content of rhenium in these nanocomposites at the level from 0,1 wt.% to 20 wt.%. Therefore, we conducted tests of production technology of that sort of material. Research and development tests in this area included full technological cycle starting from mechanical synthesis of mixture of silver and rhenium powders and ending on production of wires and bimetallic contact rivets and testing their electrical properties compared to identical samples made from AgRe10.
The pilot-industrial installation is technological line for production of contact materials. The complete line existing in the company which can be partly or completely used in production of nanocomposite silver-based contact materials consists of:
1. Medium frequency induction furnace for melting of silver and its alloys; crucible capacity 50 kg Ag,
2. Horizontal hydraulic press; max. pressure 800 ton, equipped with resistance heaters for max. heating temp of 850 °C in protective nitrogen atmosphere.
3. Vertical hydraulic press; max. pressure 400 ton.
4. Hot duo rolling mill 300 mm; rolling in temperature up to 700 °C.
5. Cold duo rolling mill 250 mm.
6. Rotary slitter.
7. Sizing duo mill 180 mm.
8. Chamber furnaces for annealing in protective nitrogen atmosphere; temp. up to 800 °C.
9. Drum-type wire drawing machines.
10. Resistance furnaces for running internal oxidation processes at max temperature of 800 °C.
11. Resistance furnaces for running continuous annealing of contacts in protective nitrogen atmosphere at max temperature of 600 °C.
12. Upset forging machines for production of bimetallic and solid contact rivets.
13. Mechanical presses for production of contact tips.
14. Accessories for cleaning of electrical contacts.
15. Control and measuring equipment to verify quality of the produced contacts
16. Atomiser with induction furnace of capacity 20 kg Ag.
17. Isostatic press; 2000 bar pressure
18. Continuous casting horizontal line
The hydrostatic and hydraulic KoBo presses were a complement to the line. These two machines were used to production of nanomaterial pilot lots: AgSnO2Bi2O310 ( hydrostatic press), AgSnO2Bi2O312 and AgZnO12( hydraulic KoBo press).
On the produced conacts the microhardness tests of contact (AgZnO12) and carrying (Cu) layers after diffusion annealing 5200 C/30min. in argon atmosphere. The obtained results are as follows: Contact type: 10BW4/1×2/2,5 Sort: AgZnO12/Cu – 116,2 HV0,2; Contact type: 6BW4/1,5×2/4 Sort: AgZnO12/Cu – 105,5 HV0,2

Contact rivets made of AgSnO2Bi2O310 nanocomposite material were implemented by RELPOL company in solar relays which were then tested to determine their applicability in operation. The scope of the tests covered: parameters checking, contact life testing, heating test.
Two tested relays performed relatively high number of switching when compared to contact life obtained with RS50 relays in the previous complete tests with standard contacts (about 10 thousand of switching). Considering contacts mechanical properties of 80 cN and tilt of about 0,30 mm the contact life of relays with application of IMN-INMET contacts can be defined at minimum 20 thousands of cycles.

Potential Impact:
According to specification of the Project end-users, Silver nanoparticles (AgNp) and silver based nanostructured composites are being frequently used in a variety of biomedical and industrial applications, such as an antimicrobial agents, lead-free solders, electric contact materials, gas-sensitive sensor, etc.
The Project will help to solve the most complicated Silver using problems, related to:
i) recovery of silver from ore waste materials. The recycling of EAF dust closes the material loop between the steel and the zinc industry. The steel at the end of its use is recycled as scrap in electric arc furnaces for producing new steel. During this process the zinc coating is going to the dust. Nowadays still more than 50 % of the generated Zn containing dust is lost by sending it to landfill, which means an annual loss of 600 to 800,000 t of zinc. The advanced MAREC technology for Zn recovery metallurgical slag residues allows to increase the recycling capabilities of the European metallurgical plants. Application of MAREC technology will result in improvement of environment and net economic benefits.

ii) controlled synthesis of metal nanoparticles of well-defined size, shape and composition. Silver had begun to play an important role for the biocide and biomedical applications. As it can be seen from the table below silver consumption has drastically increased in the last 9 years. So is the demand for silver. According to the Silver Institute a 600 % increase in the demand of silver for biocide application was reported. (http://www.silverinstitute.org/supply_demand.php).

iii) nanoparticles incorporation into implant surface layers. The total orthopedic and dental market will be about 49.5 Billion In 20012. Ag Np coatings usually make up 15 % of the implant cost. Thus, the total coatings market would be approximately $ 7.43 Billion. If application of AgNp coatings can capture even 0.25 % of that market, that would result in annual revenue exceeding $ 18.5 Million. Eventually, the coating business can be extended from orthopedic and dental implants to other devices, such as vascular stents with a $ 3 billion worldwide market only (about 1.5 billion in USA) growing at an annual rate of 15 %. NANOMINIG will create high reliable components for these end-users. As a result, market growth will be observed not only for direct end-users, but also for other companies manufacturers of similar components.

iv) synthesis of Silver based nanostructured composites for industrial purposes. The development in technology and technique for energy supply is closely related to the progress in production of electric connectors. Electric contacts are one of the crucial components of the connectors. The requirements established for those products are becoming more strict and demanding, especially with respect to the resistance to arc erosion and contact life. The main objective for launching of three new contact materials improved with respect to technology and both physico-mechanical and operation parameters is to increase their life and, in consequence, reduce cost of their application.

Contribution to developing S&T co-operation at international level. European added value
The Project objectives require a European approach due to the following reasons: Commercialization efforts in Europe in this area are relatively weak, with only half as many companies as in the United States (www.nature.com/naturebiotechnology). So is the number of publicati ons and patents in the field of, as it is called, nano-medicine. In the global marketplace, commercialization efforts in the United States are most advanced: about 50 % of all companies developing or codeveloping nanomedicines are based there, whereas 35 % are in European countries. This indicates a relative weakness of the commercialization efforts in the EU in the nanomedicine sector with currently the highest market potential. Acceleration of integration of partners from Poland, European Research Area and Mexico is very important. Cooperation in the frame of the Project will open new markets for partners. For example, even at the stage of Proposal preparation INOP pilot plant established close cooperation with companies from Germany like a supplier of powder metallurgy parts. It would also directly influence the cooperation within the project frames but also after it finishes that in the end will lead to the increase in turnover both for Mexico and European companies. Project training program to be realized by INOP (Poland) through hosting of young researcher groups from partners. It will help successful dissemination of the novel technologies in all European countries. It is necessary to underline that core Project partners (INOP, IfU) are involved European Technology Platforms: EuMaT “Advanced Engineering Materials and Technologies” and MANUFUTURE “Future Manufacturing Technologies”, ETP SMR “Sustainable Mineral Resources” and MINAM “Micro- Nanomanufacturing”. The Project goals based on emergency European industrial needs defined by these platforms.

Contribution to policy design or implementation
Contributions to standards. NANOMINIG contributions to standards will not be immediate. However, through some of the results, NANOMINIG may influence some future standards like:
-Standards for recovery of silver from ore waste materials and the controlled synthesis of metal nanoparticles of well-defined size, shape and composition;
-Standardisation of nanomaterials for implant industry: this will request first to address all health care issues, which can somehow frightened the European Community;
-Standardisation of Ag-based composites to be applied in electrical contacts.

Contribution to EU policy objectives. Independence of the European industry: NANOMINING will ensure the availability of a critical technology on European market. It will guarantee a competitive European supply chain having better quality standards in design and development than Japan or US suppliers.
The transfer process from research to industrials is generally seen as a very low process. NANOMINIG will exploit directly high level and recent research in several domains: nanomaterials, coatings and medicine. NANOMINING will be a clear demonstration that the transfer process can be improved if both industrials and researchers share common interests for high quality and innovative technologies.
Large involvement of SMEs: Three SMEs are partners in NANOMINING. They contribute to 40 % (in participation) and 44 % in EC contribution. This strong participation is justified by the needs to address new and specific solutions, which are not available in the existing equipment suppliers/processes chain.

Improving the quality of life in the Community :
The main goal of the Project is to develop:
i) Clean and efficient procedure of silver recovery;
ii) Combined nanotechnology of biological synthesis of AgNp and development of technology for deposition of coatings containing nanoparticles on implant surface;
iii) nanostructuring technology of Silver based nanocomposites manufacturing for electrical contacts.
The main influence in improvement of quality of life is related to improvement of environmental conditions in Europe due to ecologically friendly technology of waste treatment. Improving safety and security will be reached though developing highly reliable products: implants and electrical contacts. Special attention will be paid on safety of all cycles of operation with nanoparticles.

Provision of appropriate incentives for monitoring and creating jobs in the Community
Community societal objectives. Improving safety and security will be reached though developing highly reliable products: implants and electrical contacts. Special attention will be paid on safety of all cycles of operation with nanoparticles.
Growth in this market area requires a lot of technical work, so that new jobs have to be implemented. The Project will lead to create new jobs for suppliers of AG nanoparticles, For Project direct end-users expected increase of employment will be 10 %. The demands on documentation of technical and quality aspects are extremely high, so that mainly the technical sales department and quality assurance would be affected. At least ten additional employees with technical background will be needed for end-users within one year after the successful termination of the project.
Education and training program will solve the following tasks: to form education/training network integrating all the partners and the interested parties outside the Consortium; To link project S&T activity with EC education program ERASMUS; To promote new forms of education: full cycle of e-education, e-learning, interactive e-training, remote learning (Web and telecommunications); Development of novel M. Sc. Specialization (INOP in cooperation with Poznan University of Medical Sciences): “Nanomaterial technologies for medical implants.

Supporting sustainable development, preserving and/or enhancing the environment (including use/conservation of resources):
Nanotechnology Approach in Precious Metal Recovery from Ore and Metallurgy Wastes. In consequence of a high industrial expansion, large quantities of industrial wastes are accumulating in many countries and cannot be disposed without prior special treatments. In particular, waste products from the mining and metal refining industries, sewage sludges and residues from power station and waste incineration plants can contain heavy metals at high concentrations. For this reason they cannot be disposed into wastewaters plant treatment and must be submitted to special treatment in order to reduce metals content. Besides, some waste products containing high concentration of metals (copper, zinc, lead, chromium, etc.), may be regarded as a secondary source of metals. So, the treatment of polymetallic sulfide ores containing gold, silver or both, along with base metals is of great importance for both Europe and Mexico. The NANOMINING concept of enhancing gold and silver recovery from the tailings is focused on firstly decomposing the jarosite minerals by mechanical activation (milling nano- and microparticles) [P. Baláz, E. Dutková, Fine milling in applied mechanochemistry, Minerals Engineering 22 (2009) 681–694] and then secondly by thermal oxidation. The mechanical activation and thermal oxidation of residue compounds alleviate and accelerate the following leaching of gold and silver. Additionally it allows to apply thiourea or thiosulphate leaching instead of cyanide one. It is envisaged to use the microwave heating technology in fluidized bed reactor.

Biosynthesis of Nanoparticles Using Desserts Plants as a Reducing Agent. In the area of nanotechnology, the development of techniques for the controlled synthesis of metal nanoparticles of well-defined size, shape and composition is a big challenge. Metal nanoparticles exhibit unique electronic, magnetic, catalytic and optical properties that are different from those of bulk metals. This could result in interesting new applications that could potentially be utilised in the biomedical sciences and areas such as optics and electronics. Various chemical and physical synthesis methods, aimed at controlling the physical properties of the particles, are currently employed in the production of metal nanoparticles. Most of these methods are still in the development stage and problems are often experienced with stability of the nanoparticle preparations, control of the crystal growth and aggregation of the particles. The use of the highly structured physical and biosynthetic activities of microbial cells for the synthesis of nanosized materials has recently emerged as a novel approach for the synthesis of metal nanoparticles.
The use of plants and extracts for the nanostructure synthesis is an existing possibility that has not been explored extensively and can emerge as an alternative procedure to the existing physical and chemical methods. The use of plants for the nanoparticles synthesis can offer several advantages over other environmental biological process since it eliminates the elaborated process of microorganism culture maintenance. Hence, the research of vegetal sources for the metallic nanostructure synthesis to be incorporated to conventional materials (polymers, ceramics, etc) represents a great opportunity. Among the vegetal species evaluated for the nanoparticles synthesis (mainly for silver and gold) are alfalfa, oat, tamarind, Neem tree, grosella espinosa, sabila, alcanfor tree, geranium.

List of Websites:

www.nanomining.eu

Project Coordinator - Dr. Hanna Wisniewska-Weinert, email: weinert@inop.poznan.pl
Scientific Coordinator - Prof. Volf Leshchynsky, email: leshchynsky@inop.poznan.pl
Scientific Consultant - Prof.. Mikhail Ignatev, email: ignatev@inop.poznan.pl