Production of chromium iron alloys directly from chromite ore

Abstract

A process for producing chromium iron alloys suitable for steel making directly from chromite ore wherein fines of chromite ore with additions of carbon fines, and accelerant and a binder are agglomerated and the dry agglomerates are fed into a reaction vessel with natural gas as a reducing agent at elevated temperatures adequate for reduction for thereby producing a chromium iron alloy suitable for steel making. The preferred accelerant is an alkali in the form of an oxide, hydroxide or carbonate, sodium hydroxide being preferred.

Description

CROSS REFERENCE[0001]This application claims the benefit of U.S. Provisional Patent Application No. 61 / 893,400, filed on 21 Oct. 2013, for PRODUCTION OF CHROMIUM IRON ALLOYS DIRECTLY FROM CHROMITE ORE, the entire contents of which are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]This invention pertains to the production of chromium iron alloys directly from chromite ore.[0003]Chromium is an irreplaceable ingredient in all grades of stainless steels. It is the ingredient that renders steel “stainless”. It is present in alloys in amounts from 12% to about 35% Cr, with generally the more Cr the more corrosion resistant. It is also a key ingredient in the high end “super alloys” used for turbines and jet engines. Chromite ores are the only source of chromium. The majority of chromite ores are processed into an intermediate product called high carbon ferro-chrome, or charge chrome, an alloy containing greater than 50% Cr, about 6-8% C, varying amounts of Fi (0-4%, de...

AI Technical Summary

Benefits of technology

The present invention provides a process that has the following benefits:

Problems solved by technology

Prior to the development of the AOD process, and its various derivatives and hybrids, stainless steel was very expensive to produce because the intermediate low carbon product required a tricky and time consuming decarburisation step using chromite ores.

The source of the chromium in the stainless steel is partly from the recycling of scrap, but this is limited by the availability of such materials, particularly in developing countries.

This process is extremely energy and carbon intensive.

Production of low carbon FeCr alloy by aluminoghermic reduction directly from chromite ores has not generally been practiced because of a generally unfavorable energy requirement, especially with low grade ores.

There are no commercially viable deposits of chromite ore in the USA and all ferro chrome used in the production of steel is imported, typically from South Africa and Kazakhstan.

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