Resumo

SOKHANVARAN, S.; PAKTUNC, D.  e  BARNES, A.. NaOH-assisted direct reduction of Ring of Fire chromite ores, and the associated implications for processing. J. S. Afr. Inst. Min. Metall. [online]. 2018, vol.118, n.6, pp.581-588. ISSN 2411-9717.  http://dx.doi.org/10.17159/2411-9717/2018/v118n6a4.

As part of a broader programme to fully characterize the chromite ores discovered in the 'Ring of Fire' region of northern Ontario, NRCan and private research facilities in Canada have performed extensive test work over the past six years. The studies focused on developing alternative approaches for producing ferrochrome at lower temperatures and with fewer greenhouse gas emissions. The use of various fluxes or catalysts for accelerated direct reduction had yielded promising results, particularly with caustic soda (NaOH). The initial work had been protected by a patent known as the 'KWG process'. The most recent work by NRCan has confirmed that the addition of NaOH to chromite ores in carefully controlled amounts leads to high degrees of metallization at much lower temperatures than would be achieved by conventional smelting technologies, at greatly accelerated reactions rates. This paper summarizes the key findings of the latest work, including the role of NaOH in the reduction process and parameters influencing the degree of metallization and alloy particle growth. The paper will also discuss the implications of the results with respect to benefits, challenges, and opportunities for processing Ring of Fire chromite ores into saleable chrome units.

Palavras-chave : chromite; ferrochrome; prereduction; direct reduction; catalysts; Ring of Fire.

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