Periodic Reporting for period 2 - RemovAL (Removing the waste streams from the primary Aluminium production and other metal sectors in Europe)
Reporting period: 2019-11-01 to 2021-04-30
Bauxite Residue from the alumina industry is stockpiled at a rate of 7 Million tons on dry basis per year in Europe:
• With an average iron oxide content of 40wt%, can be considered as an equivalent of 3.4 Mt of iron ore available in Europe. This results into a 4% decrease in iron ore imports and a 18% increase in European iron ore production.
• With an average alumina content of 20wt% and an inherent clay-like behaviour BR is a valuable raw material for various building applications; Recycling the alumina and soda (2-4%wt) of the BR back to the alumina refinery will lead to practically 100% extraction efficiency of alumina from bauxite ore.
• BR is a considerable resource for REE. Extracting the REE from AoG’s annual BR production can meet the needs of approximately 10% of the European REE demand.
• Ga is found in bauxite ores at levels of 30-80 g/t and is dissipated in the alumina and BR streams; extracting Ga from both the BR and Bayer liquor from a single European alumina refinery would amount to global levels of Ga production (annual world production 284 t in 2012)
The RemovAl project will combine, optimize and scale-up developed processing technologies for extracting base and critical metals from such industrial residues and valorising the remaining processing residues in the construction sector. In RemovAL, 6 innovative pilot plants will be run in 5 EU countries. Combined they will form a network of technological nodes, enabling optimum processing flow sheets for valorising the produced Bauxite Residue (BR) from alumina refineries along with other industrial by-products like Spent Pot Lining (SPL) from aluminium smelters. These technologies can then be adjusted to suit all kind of BR compositions around Europe. The validation will be done for 3 European alumina producers (represeanting 44% of the European alumina production) and one legacy site owner, present in the consortium
-Dealkalinzation Technology:Laboratory tests confirmed that for three tested samples of BR the required decrease in residual alkali to the value below 0.5% was achievable. Pilot plant unit has performed its first tests at MYTILINEOS, proving the ability to produce Greek BR with less than 0.5.% wt Na2O content.
-Soil Cement technology: Laboratory tests confirmed that by using the samples of BR received from the Aughinish plant (Irish BR), it is feasible to produce a blend of materials suitable to be used as sub-base for heavy traffic roads.
-Production of lightweight aggregates : Laboratory tests on 4 different BR by ZAAK showed that lightweight aggregates (Smart Spheres) can be produced in all cases .The Pilot Plant has been commissioned and demonstration work will start in the next months
-Production of high performance binders: A maximum compressive strength of 120 MPa was achieved after 28 d for alkali-activated mortars using as precursor a mix consisting of 82 wt% of BR.. The process was demonstrated successfully at pilot scale with 5 tons of bauxite residue
-Production of ferro-silicon alloy : A total of 16 electric arc furnace smelting tests were carried out at Elkem, in a 100 kW electric arc furnace, where a total of 722 kg pig iron and 1928 kg of slag was produced. A maximum silicon-content of 3.35 wt% and 2.93 wt% in the produced pig iron was achieved
-Hydrometallurgical processing of slags:Lab scale tests regarding the leaching of high silicon slags by dry digestion were carried out and parameters for the pilot tests were defined. MYTILINEOS has processed 300 kg of BR slag produced extracting approximately 70% of the aluminium content. The solid residue of this leaching process, has been tested for Sc recovery.
-Removal has produced a first document about policy issues on BR reuse.
Plerimianry economo-technic analysis of RemovAL technologies shows that there is potential for viability and combination between them. Main target of the project remains near zero-waste and near break-even holistic processing of BR and other wastes.
RemovAL will not only provide a sustainable solution for the management and valorisation of BR and SPL– a significant social, environmental and economic problem of the alumina and primary aluminium industry – but it will further demonstrate the overall potential for sustainable industrial processing through process and material cascading and cross-sectorial financial joint ventures. This paradigm of enhanced industrial ecology is by far a greater benefit for the European industry and the European technology research community than the individual technological breakthroughs and product innovations established in each processing step of the flow sheet. Industrial symbiosis and waste-to-resources/zero-waste processing have long been identified as key pillars for a more sustainable and resilient EU industry.