Mineral processing involves balances between conflicting demands of energy consumption, yield, productivity, efficiency, safety and environmental impacts. There is a wide variety of mineral types and processes and what is the best approach for one situation is not necessarily the best for another situation. In the SEESIMA project some new processes were investigated to investigate their potential to improve the performance over current approaches. The project results with potential for improved practices in mineral processing are summarised here.

Size Reduction/Liberation

  • The layout of the size reduction and separation processes can be optimised to give improved performance in terms of reduced energy consumption and reduced wastage. Read more here.
  • Dry grinding is an interesting alternative to the traditional wet grinding for size reduction. While the energy consumption is higher than wet grinding, the use of grinding aid additives can reduce the energy consumption.

Separation

  • Text coming…

Waste Reduction

  • Mining waste was used to produce ceramic building material. While technically feasible further work remains to establish the economic viability. Read more here.

Wastewater treatment

  • Bacterial cultures isolated from locally obtained samples were shown to be able to reduce sulphate to sulphide in cold conditions, with temperatures as low as 6 deg C. Low cost carbon sources were tested and the process was demonstrated with a continuous up-flow biofilm reactor. At a temperature of 11,7 deg C, 87% of the original sulphate was removed, at a rate of 4500 mg/(litre.day).
  • Bacterial reduction of sulphate to sulphide also allows the removal of metal ions in the form of insoluble metal sulphides.
  • Sorbents were developed and tested under different conditions, such as acidity. The sorbents included aminated peat and heat-treated brucite (Mg(OH)2).
  • A two stage treatment system is demonstrated, whereby the first stage reduces the sulphate content, precipitating metal ions as sulphides and improving the sorbent performance at higher pH in the second stage.
  • The potential for wastewater treatment with membranes has improved with the introduction of new technologies such as nanofiltration and ceramic membranes and membrane distillations. Treatment costs have come down to US$1,3/m³, improving the cost-competitiveness. Currently the majority of the full-scale implementations are in gold processing operations. Read more here.