The Reduction Process and Reducibility of Chromite with Carbon

Abstract

In the present work, various chrome ores and relatively pure chromites separated from them were reduced with powdered graphite over a temperature range of 1050° to 1400°C under a flow of argon.
The results obtained are as follows:
1) Roughly speaking, the reduction process of natural chromite consisted of the following three stages:
2) The reduction products of the 1st stage were metallic iron and cementite, while the chromium-bearing product, (Cr, Fe), C₃, was produced after the beginning of the 2nd stage.
3) Of the constituents of chromite, iron oxide had the strongest influence on its reducibility. At tem peratures below about 1200°C, the porosity of chromite particles was also of great interest, and porous chromite was reduced more easily than compact chromite.
4) At temperatures above 1300°C, a considerable portion of SiO₂ contained in chrome are was reduced.
5) The gangue minerals such as forsterite and enstatite retarded the reduction of chromite at temperatures below 1250°C, but accelerated it at higher temperatures.