Pyrometallurgical Processing of Iron Manganese Ores: A Review with Emphasis on Kazakhstan’s Mineral Resources and Technological Prospects

The depletion of high-grade manganese ore reserves, accompanied by the progressive decline in ore quality, has intensified concerns regarding the supply of suitable manganese raw materials for Kazakhstan’s ferroalloy industry. Under these conditions, the development of efficient processing technologies for iron manganese ores characterized by low Mn/Fe ratios and complex mineralogical compositions has become increasingly important. This review examines current pyrometallurgical approaches for the processing of iron manganese ores, including carbothermic reduction roasting followed by magnetic separation, reduction smelting for the production of rich manganese slag, and hydrogen-based selective reduction followed by magnetic separation. Particular attention is given to the mineralogical and chemical characteristics of Kazakhstan’s iron manganese ores, which significantly limit their direct utilization in conventional ferromanganese production processes. The advantages and limitations of these technologies are critically evaluated in terms of metal recovery, Mn/Fe upgrading efficiency, energy requirements, environmental performance, and industrial applicability. The comparative analysis identifies reduction smelting as the most suitable route for Kazakhstan’s iron manganese ores under current technological conditions. This conclusion is primarily supported by the low Mn/Fe ratios, elevated iron contents, and complex mineralogical associations characteristic of the major Kazakhstan deposits, which limit the efficiency of solid-state reduction followed by magnetic separation. During smelting, the original mineral structure is destroyed, and iron and manganese are separated directly between the liquid metal and slag phases. Published studies report iron recoveries exceeding 95%, MnO recovery to the slag of approximately 94.6%, and Mn/Fe ratios above 15 in the resulting rich manganese slag. In addition, the process produces two potentially marketable products-cast iron and rich manganese slag-and can be integrated more readily into Kazakhstan’s existing ferroalloy production infrastructure. Therefore, reduction smelting currently represents the most technologically mature and practically feasible route for the comprehensive utilization of Kazakhstan’s iron manganese resources.