Properties of Ferrochrome

Over 80% of the world's Ferro-chrome is used in the production of stainless steel, which is defined as a steel alloy with a minimum of 10% chrome by content, the average chrome content being 18%. Stainless steel depends on chrome for its appearance and its corrosion resisting properties.

High Carbon Ferro-Chrome is most commonly used in specialist applications such as engineering steels. Lower carbon ferro-chromes are produced in smaller quantities for more specialized applications.

Production of Ferro-chrome
 

The two main products of chromite refining are Ferro-chrome and Chrome Metal. For the production of Ferro-chrome the chromite ore is reduced, usually by coal and coke in a high temperature reaction to form the iron-chrome alloy. For production of pure chrome the iron has to be separated from the chrome in a two step roasting and leaching process. Over 80% of the world's Ferro-chrome is utilized in the production of stainless steel, which is defined as a steel alloy with a minimum of 10% chrome by content, the average chrome content being 18%. Stainless steel depends on chrome for its appearance and its corrosion resisting properties

Ferro-chrome is often classified by the ratio of chrome to carbon it contains. The vast majority of ferro-chrome produced is Charge Chrome. It has a lower Cr:C ratio and is most commonly produced in South Africa for use in stainless steel production. The second largest segment of the market is High Carbon Ferro-chrome which has a higher chrome content, being produced from higher grade chrome ore.

High Carbon Ferro-chrome

With a chrome content from 60% minimum, there are several variations on High Carbon Ferro-chrome with carbon contents of:

Cr : 60 %

Si :  3 - 3.5% Max

P :   0.35% Max

S :   0.35% Max

C :   6 - 8 %

Low Carbon Ferro-chrome

Low Carbon Ferro-chrome is produced by reducing chrome ore with Ferrosiliconchromium, typically the chrome contents are minimum 60% with carbon contents ranging from 0.03% to 0.15% sometimes higher depending on the origin. It is used for trimming additions in stainless steel production as well as other specialist applications. It is added by stainless steel producers in the last stages of production to add precise amounts of chrome without affecting the carbon levels. An intermediate-carbon Ferro-chrome is produced by further refining of Charge Chrome by blowing oxygen and steam through hot molten Charge Chrome to reduce the silicon and carbon levels. Typically the carbon is reduced to below 1.5%.

Cr :  60 %

Si :  1.5% Max

P :   0.35% Max

S :   0.35% Max

C :   0.03%