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  • Periodic Reporting for period 1 - OptimOre (Increasing yield on Tungsten and Tantalum ore production by means of advanced and flexible control on crushing, milling and separation process)

OptimOre Report Summary

Project ID: 642201
Funded under: H2020-EU.3.5.3.

Periodic Reporting for period 1 - OptimOre (Increasing yield on Tungsten and Tantalum ore production by means of advanced and flexible control on crushing, milling and separation process)

Reporting period: 2014-12-01 to 2016-05-31

Summary of the context and overall objectives of the project

Modern economy is highly dependent on specific raw materials, and it is envisaged that this dependency will increase in the near future. Most of them are scarce in the European Union (EU) and of poor purity, being mixed within complex aggregates (low grade) which need to be processed by means of an inefficient energy and water consumption in the separation process and with high exploitation cost. Tungsten and Tantalum ores are two recognized Critical Raw Materials: Tungsten production has been lacking in recent years despite these are relevant ores for industry and electronics (among many other applications). On the other hand, Tantalum is a key element on electronics with clear European external production dependency, as it is naturally scarce in Europe.
The main objective of OPTIMORE (Increasing yield on Tungsten and Tantalum ore production by means of advanced and flexible control on crushing, milling and separation process) is to optimize the crushing, milling and separation ore processing technologies for Tungsten and Tantalum mineral processing, by means of improved fast and flexible fine tuning production process control based on new software models, advanced sensing and deeper process physical study increasing yield in 7-12% on the current best production processes, increasing energy saving on a 5% compared to the best available techniques. The general objectives progress of the project is indicated in the table 1:
One work package of the project is ore production documental and system analysis and provides the basic analysis for successful project execution, including technology watch, European CRM perspective and technological selection. This WP focus on to settle up the starting point of the project with the most advanced State of the Art (SoA) technologies available and to perform a constant SoA and market watch for the selection of the most adequate techniques and assure advanced with respect to current SoA. The fulfillment of these objectives is in accordance with the scheduled chronogram.
The first step in the ore processing is crushing and work package 3 (WP3) develops its modelling. The first task in the WP3 has been to determine which machines and what settings that could be manipulated in order to improve performance and to satisfy the needs and goals set by the OptimOre project. The challenge to increase production yield when extracting rare earth elements and to be able to save energy when doing so requires a schematic view and a fundamental understanding on diverse crushing machines.
Work package 4 covers all the grinding modelling of tantalum and tungsten ores. In parameter characterization and selection, the input and output parameters of grinding devices have been selected and studied. The best models in the literature have been selected for its study. In-lab test for data gathering is executed and different assays have been executed for characterization. The following task is test registering and physical models generation, where the data of the experiments is analysed and mathematical and physical models will be developed. At this stage, new high pressure grinding rolls and ball mill models have been developed. The last task is onsite test system development, where the models are tested within a real site environment for model verification and its error measurement.
In the gravity separation work package, the experimentation has been completed for the development of a quantitative mineralogy based model of shaking tables. Initial empirical models have been developed and validation testing using ore material from Drakelands mines and the Penouta deposit are scheduled to be completed. Video footage of each experiment was captured and investigations into the use of artificial vision have begun. Experimentation is 75% completed for the modelling of the Mozley MGS multi-gravity separator.
The second separation process studied is magnetic separation (WP6) which develops the models for the prediction of Wet High Intensity Magnetic Separator performance. In fulfillment of the first WP-task, a literature study of existing magnetic separation models has been undertaken. A new model combining all influences in the process must be developed. MLA and quantitative petrographic rock fabric analysis are used to analyze material parameters. With information from the parametric study, predictions for recovery and grade of the magnetic separation product can be made depending on the process parameters. With a simulation of the process, helpful conclusions about the procedure can be drawn. The influence of the magnetic force and particles on the material stream as well as the process control could be tested on such a simulation model.
The Froth Flotation Package (WP7) is focused on developing improved models for the prediction of processing results from tantalum and tungsten ores. To enhance already existing models, WP7 investigates the potential contribution of Mineral Liberation Analysis. WP7 must gather information from various sources: particle information (adding MLA), flotation information (based on flotation test work), fundamental models and empirical models. Combining all information allows for froth flotation simulation through process mineralogy and modelling (Fig. 1).
WP7 must work together with WP8 to do process control modelling. WP8 also aims at predicting froth flotation results, but through the monitoring of the variations within control parameters and establishing dynamic relationships between said parameters.
WP8’s main objective is to design an expert control system for Ta and W comminution and separation processes, to reduce energy consumption and yield increase. This WP involves sensing, modeling and control design; support to/from other partners is required. EDMA is currently working on the development of a central sensor platform for data collection and developing the expert control system module for simulation and control of the process (Fig.2). Initial studies on expert knowledge and control, and artificial intelligence techniques, are being used for the model parameters adjustment of the crushing, milling (Fig. 3) and separation models of Ta and W. The work continues with the dynamic modeling (Fig. 5), application of AI techniques and expert control of the process (Fig. 4).
All technologies need to be validated. The objective of this work package (WP9) is to integrate the hardware and software elements for validation and further validation carried out in the field. The validation will be carried out in three stages:
• Virtual simulated environment using proprietary software and expertise;
• Pilot test plant facility (UK);
• As many actual mine operating sites as possible within Europe;
It is managed to include the Penouta Tantalum Project under development of Strategic Minerals Spain as validation site.
Finally, dissemination is carried out by WP10. This work package will co-ordinate exploitation strategies and project-wide training, communication and dissemination activities in order to ensure project awareness, knowledge sharing, and dissemination of project results to the mining machinery production. The work package will use a variety of communication means to engage with and influence the target groups, understand and address their needs and deliver appropriate communication at appropriate times. Communication with relevant actors within the field of mining production systems will be pursued, meanwhile access to them through associations and relevant actors will be developed. The project results are expected to be provided as free knowledge access through publications.
Exploitation and Dissemination are two relevant parts of the project, but given the high number of WPs it has been agreed to merge both into this single WP.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The financial management includes the surveillance of budget and resources, coherence of plan and execution and the coordination of the financial management procedures for a correct fulfilment of the Grant Agreement has been carried out. It includes preparation and logistics for meetings (43 meetings), assemblies (6 General assemblies) and Project Reviews. Management – set up as well as surveillance and update - of all kind of contractual, administrative and financial documents, but also mediation and coordination among the consortium partners and with the EC has been the responsibility of the coordinator. The results so far are 5 milestones completed and 38 deliverables submitted.
More than 140 relevant evidences on W and Ta were selected, and classified according to its content and source. The European CRM perspective, where the already existing and potential future geological deposits of Ta and W, were analyzed, along with geological information throughout Europe. This work was mainly based on the reports of the Ad-hoc Working Group on defining critical raw materials (2014 issue) and the available information of a number of mining companies. The last one is Technological selection where a selection of the best available technologies should be made at this point, but due to the low number of processing plants in the EU, the range of available technologies and the variety of mineral associations in the ores, it was decided that no technology is going to be ruled out at that point.
The crushing modelling was focused on the comminution machines e.g. jaw, gyratory and cone crushers, energy based crushers as Vertical Shaft Impact (VSI) and Horizontal Impact Shaft (HSI) and High Pressure Grinding Rolls (HPGR). These crushers ability to reduce particle size and suit the purpose of increasing the yield of CRM may vary and it is therefore important to extract knowledge regarding these different crushers´ specific characteristics. Deliverable D3.2 shows how characterization of the rock breakage behaviour with the aid of piston and die test, SEM and geochemical analysis acts as an important tool for identifying how much rare earth elements that are liberated. Deliverable D3.3 the developed cone and jaw crusher models are described. The deliverable describes the performance of the crusher models. The models can predict particle size distribution (PSD), capacity and power consumption.
The grinding modelling has completed the state of the art of the different types of grinding equipment. Different models in the literature for each device have been studied. The parameters affecting the milling have been studied too. In the mineral characterization for milling, an initial characterization for all the minerals of the project have been carried out. Then, the physical characteristics of these ores have been tested. Finally, the mineral liberation analysis of some of those minerals have been studied and modelled with Beta distribution. In high pressure grinding rolls modelling, three models of the literature where studied and compared to see which one fits better. After that, a new model has been presented in order to improve the other models.
The gravity separation modelling started with characterization of the mineralogical and chemical composition of the Penouta Balsa Grande tailings sample using QEMSCAN and XRF. Gravity separation tests were conducted on the Penouta sample using the Mozley separator, Knelson and Heavy Liquid Separation (HLS). Currently we are conducting shaking table tests on the synthetic ore sample aiming to obtain effective parameters for the modelling of gravity separation systems.. Experimentation to develop a quantitative mineralogy based model for assessing performance of wet shaking tables has been completed on a synthetic ore sample aiming to obtain effective parameters for the modelling of gravity separation systems. An initial empirical model has been developed based on these results. Material from Drakelands mine and the Penouta tailing have been prepared for initial validation studies. We are also assessing the potential for automated control equipment for grade control with the shaking table. Over 30 tests were completed to optimise test conditions. The work package has begun to create a model linking mineralogy to the performance of the Mozley multi-gravity separator.
Regarding magnetic separation (WP6), in the literature study it was found out, that a new model combining all influences in the process must be developed. This can either be done by an experimental or simulative approach. Studies are focused on material from Penouta, (Ta-ore) and Panasqueira (W-ore). Material preparation and parametric studies are commencing. The feed for the magnetic separator is the product of gravity separation. For realistic experiments gravity concentrate would be necessary. This is complicated due to the large amount needed. For the experimental work synthetic mixtures resembling the gravity concentrate will be used. Material information was measured through MLA, sieving and magnetic susceptibility scales. In the launched simulative approach, the magnetic field is calculated using FEM and the slurry flow is simulated by CFD.
The Froth Flotation Package is focused on developing improved models for the prediction of processing results from tantalum and tungsten ores. To do froth flotation simulation, WP7 must gather information from various sources: particle information, flotation information, mechanistic models and statistical models. Flotation information has been gathered for two scheelite-bearing ores, independently from the original existing process, using batch flotation test work but also contact angles measurements for example. First particle information about mineralogy, particle shape or particle liberation and associations were identified through Mineral Liberation Analysis). Fundamental and empirical models have been combined and coded into software in order to identify their strengths and weaknesses.
The expert control system design begins with knowledge engineering. The partners provided expert knowledge information about the process, variables and sensors. This is to know how the process works, for modelling/control design and AI tools selection. A central sensor platform is under development too, for data collection management; also, a camera system is being developed for measuring the size of particles that flow out of a mill. These data are used for process modeling/control, which is being currently performed. Different AI techniques were studied and selected. Techniques like GA, FL and ANN seem appropriate for this project. Tests using GA were done to adjust some comminution and separation models of Ta and W. Finally, the software that simulates the process and executes the expert system is under development.
Whilst the final validation of the results will be carried out during the second half of the project, the early stages of a validation strategy have been implemented which will lead to the adoption of new technologies and practices (Fig. 6). This revolves around engaging with as many European operating companies extracting tungsten and tantalum as possible. Three such companies have been appointed on the Advisory Board and will be involved in the industrial validation work. The nature of the types of mineral deposits being exploited by the companies is such that the widest cross-section of mineral types will be tested in plant.
During this period methods of simulating the integrated mineral processing technologies have been assessed to best demonstrate the value of eventual options considered. Methods for analyzing historical plant data have also been assessed to find the most suitable method of determining rule-based relationships between the operating and control parameters.
Dissemination activities have been carried out since the commencement of the project to follow a dissemination plan (Fig. 7).
Dissemination opportunities have been identified through traditional communication channels such as event attendance (e.g. conferences, seminars, workshops, etc.), project publications (e.g. leaflets, press releases as well as conference papers, articles in professional journals etc.) and project presentations (e.g. to local stakeholders, etc.), complemented also by online activities based around the project website, and through the main social platforms (e.g. Twitter, Facebook, etc.). The dissemination activities have been designed to target the key audiences and stakeholders and to maximize awareness of OptimOre’s objectives and training workshops for industry.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

An improved understanding of how tungsten and tantalum is hosted in the ore matrix and how the metals can be liberated has been achieved from the research carried out so far and is likely to modify the established thinking on the design of the comminution stages of their processing. At the same time new approaches to sensing the mineral processes have been explored which have the potential for enabling new approaches on process control. The control processes themselves are also being readdressed to develop intelligent decision support systems rather than ones based on mathematical functions.
A list of current and near future projects (Table 2), along with a non-exhaustive list of relevant deposits is shown in the next table. It is remarkable the increasing and noticeable interest on reopening former Tungsten mines in the Iberian Peninsula, especially in northern Portugal and western-northwestern Spain in where the contact with OptimOre has increased such interest. In the case of Tantalum, the project in study Alberta 1 (Presqueiras), also located in northwestern Spain, is expected to be Tantalum ore mine with greatest production in Europe. These mentioned areas have suffered in the last years the impact of recent economic crisis; nevertheless the socioeconomic problems have an older basis because they are mainly rural based economy areas showing in the last decades a population decrease mainly due to migration displacements to urban settlements. The use of local natural resources can be one of the key foundations of economic development and population retaining.
After a review of a number of plants that could be visited, it can be noticed that there exists a noticeable gap between State of the Art on Knowledge and State of the Art on Practice. Perhaps one of the most evident lack of knowledge, and as a consequence, one of the potential field of progress beyond the State of the Art, is the intensive use of Process Mineralogy as a source of information to be used in modelling and control of unitary processes and also in the evaluation the global efficiency of the plant. In some of the visited plants, it was found that no mineralogy studies are carried out and all quality control is based just in conventional chemical analysis with no information about mineral phases present at each stage of the process or even in the marketable products. In fact, this aspect was one of the manifested interests by the producers in order to improve they general recovery; that is, producing as much marketable products as possible, even final tailings as aggregates.
Regarding the gap previously referred, perhaps it can be explained by several reasons, among them the following ones:
1- The mineral processing industry has in general a great momentum, especially when speaking on new technology implementation. Mining investments prefer assurance in the solutions chosen, without considering the opportunity cost of discarding not-proven-enough technologies. This means that new solutions have to wait to be considered as “classical” at least 2 mining cycles (30-40 years). Furthermore, solutions considered as new, especially in the field of electronics and control, are indeed proven technology (even obsolete in other fields).
2- A number of processes are preferred to be manually controlled, which usually leads to a lower than possible level of automation control.
It can be said that with the only application of best available techniques, a clear improvement in process and energy efficiencies could be achieved.

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