In December 2020, Eurasian Resources Group (ERG) reported that its Kazakhstan headquartered subsidiary, Kazchrome, had successfully completed trials for the use of floatation technology in the recovery of chromite from tailings at the Donskoy Processing Plant.
Trials of the novel floatation technology resulted in a chromium oxide recovery of 55%, with the specifications of the concentrate produced being suitable for use in Kazchrome’s captive ferrochrome smelters.
The recovery of chromite from both primary ore and tailings is most commonly achieved using spiral concentrators, which exploit the difference in specific gravity between chromite and gangue minerals to produce a chromite-rich concentrate. Although this process results in good recoveries in primary ore, spiral concentrator recoveries from tailings that have been subjected to extensive milling are generally low. This is because the gravity-based process is less effective at the finest particle sizes.
There has, therefore, been an ongoing focus on the development of alternative tailings beneficiation techniques that can yield better recoveries at fine and ultra-fine particle sizes. ERG’s recent announcement on its successful application of floatation, signals further progress in industry-wide efforts to minimise Cr2O3 losses by achieving better recoveries through the reprocessing of waste material. An increased demand for chromite fines can be linked to key structural changes in the ferrochrome industry.
High-grade lumpy ores have historically been the main source of feedstock for ferrochrome smelting but are normally priced at a significant premium to lower grade tailings-sourced concentrates. As such, the drive towards improving fines recoveries can, in part, be attributed to the increasingly widespread consumption of chromite fines across the ferrochrome industry, as ferrochrome producers look to incorporate lower cost feedstock. This shift has, on the part of ferrochrome producers, necessitated widespread investment in agglomeration technologies or specialised furnaces that are less susceptible to “de-volatisation blow-outs” during smelting of fine and ultra-fine feed.
A key consequence of any significant improvements in average Cr2O3 recoveries from tailings will be a shift in the cost structure of chromite ore supply, as larger volumes of low-cost material are brought into the market. With low-grade fines being increasingly utilised by ferrochrome producers in the production of charge chrome, ongoing improvements in fines recovery from tailings may be expected.
Roskill’s NEW Chromium Cost Model Service (CMS) is under development and will be available in February 2021, complementing the Roskill Chromium: Outlook to 2030 report (latest update published in December 2020). The CMS will provide a detailed account of global chromium ore and ferrochrome supply, as well as associated costs, while allowing the user to easily evaluate the effects of a chromium ore tax on supply, or other shifts in cost/exchange rate factors and more.