Transforming mining residues to valuable products


Pre-study – One of the environmental challenges in the mining and metallurgical industry is the pyrite tailings and waste gypsum, which its poor management could lead to acid mine drainage.The project aim was to develop and validate a novel recycling process for simultaneous treatment of gypsum and pyrite residues which are two major residues in the mining industry. The pre-study led to an application for and approval of a full-scale project, Stage II of Residue2Product, that is expected to be completed in 2026.

Stage II
Goals of the project?

  • Develop and optimize a combined novel recycling process for waste gypsum and pyrite tailings.
    -Study and optimize the decomposition of pyrite to pyrrhotite.
    -Study and optimize the production of metallic iron from pyrrhotite using fossil-free reductant.
    -Study and maximize the conversion of gypsum to CaO.
  • Evaluate the utilization of different sources of pyrite and gypsum.
  • Characterize and evaluate the generated products.
  • Evaluate the potential recovery of additional valuable metals as e.g. cobalt.

“Without SMI funding, this interesting and promising project would have not been realized. By the end of the project, I hope we will develop a detailed flowsheet for eco-friendly, efficient, and economic recovery of valuable materials from pyrite tailings and waste gypsum. By the end of the project, I also hope we will have the will and interest to go for a prototype (semi-pilot scale project)”.

 Hesham Ahmed, Associate Professor and Project Manager, Luleå University of Technology.

Next steps?

  • Postdoc arrival (expected early 2024)
  • Continue with Thermodynamic modeling including impurity minerals
  • Study the effect of different parameters on each of the proposed steps
  • Optimization
  • Study more complicated pyrite tailings and waste gypsum
  • Product and process evaluation

The results from this project will strengthen the Swedish and global mining and metallurgical industry, by providing improved management of the residues.


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