SecMinTec - Sustainable Technical Solutions for the Recovery of Economically Strategic Elements and Precious Metals at Chilean Locations

Worldwide, but especially in South America, large-scale stockpiles of old processing residues are resulting from ore mining. These contain relevant contents of precious elements. The German-Chilean project SecMinTec is dedicated to the efficient recovery of valuable metals and economically strategic elements. These are to be recovered from both ore treatment residues and mining waters.

Use of secondary sources of raw materials - tailings, mining waters, slags

Chile's extensive copper mining has left large areas of old bodies from ore processing residues. In part, these have higher residual contents of precious elements than today's primary ore bodies. Such bodies are, for example, fine-grained residues (so-called tailings) from ore floatation or residues from heap leaching. At the same time, old mining residues often cause environmental degradation, including spills from mining waters. This problem can be found in South America, for example in Peru and Brazil, but also at many other locations worldwide.

SecMinTec wants to show how valuable metals and economically strategic elements from old bodies and mining waters can be efficiently recovered. At the same time, pollutant emissions from mining waters are to be reduced. The retention of metals is linked to their recovery via ion exchangers in this case.

The project is first developing a structural understanding of tailing bodies, which will serve as the basis for the localisation of enrichment zones of precious elements contained therein. This will then be followed by a plan for the selective recovery of these enrichment zones. During belt transport, different material classes are separated by element measurements. The project is also investigating the retention and recovery of precious elements from mining waters. SecMinTec is also aiming for a holistic approach to the recovery of precious elements from slags, because this is linked to the production of water treatment materials.

Diverse approach and diverse results

The different project sections of SecMinTec follow different procedures and diverse results can be expected. The exemplary investigations on the structural understanding of tailing bodies are therefore done on various secondary mining bodies. This part of the project will develop a detailed understanding of the distribution of relevant precious metals and economically strategic precious elements in the examined tailings. A wide variety of measurement methodologies are being used and advanced in terms of economically strategic precious elements in particular. These findings are the essential basis for the planning of selective recovery, which represents a separate part of the project. A categorisation of secondary mining bodies is being created here to determine in which cases selective or general recovery is expedient. This results in essential knowledge for mining planning. In addition, in this part of the project, an adapted chemical measurement process is being advanced for conveyor belt transport for the separation of the materials. In the project section concerning the retention and recovery of valuable elements from mining waters, on the one hand, commercial ion exchangers are being tested with regard to site-specific questions. This is done with special regard to the separation of different precious elements such as copper, cobalt or nickel. On the other hand, results on natural ion exchange materials available in Chile are being generated. The project section which deals with slag leaching and the production of water treatment material identifies which slags are suitable for leaching in terms of recyclables and matrix composition. This is also linked to a process of surface enlargement in slag production for better leaching attack. As a result of the findings - including slag composition and leaching tests - schwertmannite is also being produced as water treatment material, e.g. for arsenic retention.

The processing of these various project parts is taking place in close cooperation within the project network. This is being coordinated by the Freiberg University of Mining and Technology. Decisive is the cooperation and coordination on the Chilean side by the Universidad de Concepcion. This includes the aspects of the Chilean site owners and project partners.

Application of results in South America and beyond

The project results of SecMinTec have a comprehensive and multi-layered potential for application and marketing. This applies to all of South America, and also goes well beyond it.

The project will provide a methodology for the selective recovery of secondary raw material sources from tailings and mining waters while reducing the negative environmental impact.