DOWNSTREAM PROCESSING CHARACTERISTICS OF PGM CONVERTER MATTE

摘要

There is little in-depth study on the downstream processing characteristics of solidified PGM-containing converter matte, particularly related to grinding and liberation behavior closely associated with leaching, and also as a function of mineralogy. Moreover, there is limited physical property data available, such as hardness and breakage of converter matte mineral structures that allows for deliberation on a possible dependence between mineralogy and the downstream processing characteristics of converter matte. The initial aim of this study is to investigate a relationship between indentation hardness, breakage and mineralogy of solidified converter matte mineral structures. This, in turn, allows for a subsequent investigation that aims to relate the mineralogy to the integrated downstream processing characteristics of solidified converter matte.A nano-indentation tester was specifically used to measure the indentation hardness of mineral structures. The indentation system also had the ability to test the breakage characteristics of the respective mineral structures by applying a preset load. Laboratory batch grinding tests were conducted at various specific energies with respect to solidified high and low iron mattes. A high resolution field-emission scanning electron microscope was utilized for mineralogical analysis. The perfectly mixing ball mill model was subsequently used to assess the breakage rates of matte particles and minerals. A mineral liberation analyzer was used to investigate the liberation characteristics of mineral structures of interest. Published experimental converter matte leaching data was drawn upon to emphasize the integrated effect of mineralogy.The minerals and associated boundaries did not demonstrate the same indentation hardness. The indentation-induced breakage of nickel sulfide, copper sulfide and NiCu-alloy structures appeared preferential and related to the indentation hardness. The laboratory batch grinding of the converter mattes at specific energy inputs resulted in product size distributions correlated to the underlying mineralogy. The breakage rates at 25kWh/t were faster for copper sulfide minerals in the high iron matte compared to that of the same minerals in the low iron matte. This finding was in good agreement with that observed for the respective host particles at the same specific energy. Moreover, a higher degree of overall liberation was achieved for copper sulfide and NiCu-alloy present within the high iron matte particles compared to particles within the low iron matte. However, a lower degree of Ni extraction was achieved during leaching of minerals within the high iron matte as opposed to minerals of the low iron matte. This study has provided an integrated understanding of the downstream processing characteristics of solidified PGM-containing converter matte.