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Near-zero-waste recycling of low-grade sulphidic mining waste for critical-metal, mineral and construction raw-material production in a circular economy

Periodic Reporting for period 1 - NEMO (Near-zero-waste recycling of low-grade sulphidic mining waste for critical-metal, mineral and construction raw-material production in a circular economy)

Reporting period: 2018-05-01 to 2019-10-31

With an estimated volume of 600 Mtonne/yr and a historic stockpile of 28,000 Mtonne, sulphidic mining waste from the production of Cu, Pb, Zn and Ni, represents the largest volume of extractive waste in Europe. When poorly managed, these “tailings” may cause major environmental problems such as acid mine drainage. In 2016 EIP Raw Materials launched a “call to arms” to transform the “extractive-waste problem” into a “resource-recovery opportunity”, as “tailings” still contain valuable & critical metals. Using a “4 PILOTS – 2 case-studies” concept, NEMO develops, demonstrates and exploits, therefore, new ways to valorise sulphidic mining waste. The 2 cases are the Sotkamo Ni-Co-Zn-Cu mine in Finland and the Luikonlahti processing facility in Finland; the 4 PILOTS are located at key points in the near-zero-waste flowsheet, encompassing the recovery of valuable & critical metals, the safe concentration of hazardous elements, the removal of sulphur as sulphate salts, while using the residual mineral fraction in cement, concrete and construction products. NEMO has established an interdisciplinary consortium, including 8 industrial partners (2 mining, 4 engineering, 1 machine manufacturing & 1 construction material company), 4 research institutes, 2 universities and 1 civil society group.
Leaching (bioleaching, alkaline pressure leaching) and metal recovery (chemical precipitation, solvent extraction) works have started by studying various samples from the mines. The samples' mineralogy, content of valuable and/or harmful elements, possible processing technologies and work-safety has been scrutinized in order to optimize the processing parameters. Initial work was dedicated to sampling, preparation (crushing, grinding, splitering) and characterization of Sotkamo mine residues that were then used to perform preliminary laboratory tests prior to demonstration operations. Bench-scale bioleaching tests were performed by BRGM in laboratory stirred tank bioreactors using selected microbial cultures in order to determine preliminary leaching kinetics and metal yields as well as acid requirements. These tests confirmed that the presence of microorganisms is required to recover Ni, Co and Zn remaining in Sotkamo residues. From the experimental results, a comprehensive leaching scenario was drawn and a set of optimized operating parameters that will be used in the large-scale pilot experiments with the low-duty bioreactor was established. In parallel, lab-scale column experiments have been started by UoE in order to determine the interactive effects of the process solution (high metal sulfate content), pH, temperature and nutrient supply influence on microbial activity and metal leaching rate (particularly copper and cobalt) from the secondary ore. The data will be used later to design the second pilot operation (enhanced heap demonstration) that will be performed by TERRA.
In preparation of upscaling tests, VTT has upgraded chemical precipitation and solvent extraction pilot facilities to fit to the various tasks given. VITO designed, tendered and ordered the construction of a mobile aggregate production test rig. The test rig will consist of three containers: one container will consist of a supply and material storage system which is connected to a second container in which a dosing and intensive mixing unit is placed. The produced aggregates will be conditioned and cured in a third container with full air flow and climate regulation. In the next period flash calcination and aggregate production trials will take place to produce raw materials for development of the concrete end-products. The Heap Bioleaching Model and the Sulfide Precipitation models were developed and validated with data from literature, these models will be implemented in Virtual Plant which is an innovative simulation environment where the models of the NEMO pilots will be simulated in the same way as they are going to be integrated in a real plant.
In clustering activities with other H2020 projects are focused on Sustainability Assessment and Social License to Operate. Several workshops and skype meetings were organized. First contact with the EIT Raw Materials has been established.
Stakeholder analysis has been carried out and civil society engagement activities have been initiated. High-level expert panel has been established and three meetings of the panel were organized. In each meeting, a highly diverse audience discussed the various aspects of SLO bringing their expert experiences to the table. In the communication and dissemination activities, the team members participated in several events (a number of 10 event participations were reported so far: forums, clustering events, symposiums, workshops, conferences and webinars, in Greece, Spain, Belgium, UK and Poland), with a total estimated reach of about 500 persons (approx. 200 from Scientific community, 150 from Industry, 50 Policy makers, and also civil society, general public, media, investors and potential customers). The first NEMO Newsletter is ready to be published in November 2019. The NEMO website is constantly updated with relevant news. Exploitation tasks have been started and trends and business scenarios related to the NEMO exploitable results have been analyzed.
NEMO’s near-zero-waste technology will provide the EU with both direct and long-term, indirect advantages. The former range from new resources (e.g. base metals: Cu, Zn, Ni, Au; critical metals: Co, Sc, Nd, Y, Sb; SCM and aggregates etc.), CO2 savings from metal recovery and the replacement of Ordinary Portland Cement), new job creation, new revenues from the multiplication of the former benefits, while eradicating acid-mine drainage and other environmental issues, and ensuring an enhanced dialogue (framework) between industry and civil society, to obtain and maintain the License to Operate mines in EU.
A dialogue and enhanced co-operation between the mining industry, local communities, authorities and international NGO’s will be supported through improved interaction strategies between stakeholders. National and international workshops will be arranged, bringing benefits of the new sustainable mining technology into the knowledge of the different stakeholders, collecting their specified expectations and planning concrete actions. The NEMO consortium will strongly contribute to developing novel methods to use metal-containing, extractive mining waste for the recovery of valuable metals, critical raw materials and for the production of cementitious mass products. This know-how will be disseminated and exploited, for the benefit of the European mining and construction industry, as well as strengthening R&D at a European level in this field. Each of the consortium partners plays a role in the exploitation of the result.