What is ferrochrome (FeCr) and what is it used for

Ferrochrome

Ferrochrome (FeCr) is a ferroalloy which includes iron and chromium. Depending on the application, ferrochrome contains between 50 and 70% chromium. It comes from the reduction of chromite, a mineral composed mainly of chrome oxide and iron oxide and mined as chrome ore.

Ferrochrome is the most important intermediate raw material for the production of stainless steel and uses the majority of the world’s chrome supply.

%

of the world's ferrochrome is used in the production of stainless steel.

What is ferrochrome?

Ferrochromium is made using metallurgical grade chrome ore and can be divided into three categories, depending on the level of carbon in the alloy.

The three types of ferrochrome alloys are:

High-carbon (HC) ferrochrome (carbon content between 4% and 9%)
Low- and medium-carbon (LC & MC) ferrochrome (carbon content less than 0.5% for LC and between 0.5% and 4% for MC)
Ferrochrome-silico-chrome (FeSiCr)

Ferrochrome applications

Production of steel, especially stainless steel with chromium content of 10 to 20%, is the largest consumer of high-carbon ferrochrome. Over 80% of the world’s ferrochrome is used in the production of stainless steel.

The vast majority of ferrochrome produced is charge chrome, which has a lower chrome content ratio. Used most commonly in stainless steel, it is mainly produced in South Africa.

Low carbon and medium carbon ferrochrome is used in the manufacture of special steels. Low carbon ferrochrome can be used to produce superalloys.

Charge chrome and high carbon ferrochrome

Both charge chrome and high carbon ferrochrome (HC FeCr) contain between 4% and 9% of carbon, and the difference between these two is essentially in chromium and silicon content.

Charge chrome typically contains 45-56% of chromium and 3-7% of silicon While HC FeCr typically contains 60-70% in chromium content and 1-3% silicon.

HC FeCr can be produced by a blast furnace method, an electric furnace method, and a plasma furnace method.

The most common modern method of production of HC FeCr with high chromium content is smelting in submerged electric arc furnaces.

The basic principle of electric furnace smelting of HC FeCr is to reduce chromium and iron oxides with carbon.

Low carbon ferrochrome

Low carbon ferrochrome (LC FeCr), with a carbon content below 0.5%, is a ferroalloy used to regulate the ratio of chromium in steel production without adding carbon and other unwanted ingredients. It is also used by the superalloys industries.

The most commonly used processes to manufacture low carbon ferrochrome are metallo-thermic reductions known as the Duplex (Perrin) or Simplex processes. In order to get the desired low carbon content in the LC FeCr a carbo-thermic process cannot be used.

Medium carbon ferrochrome

Medium carbon ferrochrome (MC FeCr), with a carbon content of between 0.5-4%, is used in the foundry industry as well as in steelmaking plants where refining capacity is limited but low silicon content is desired.

MC FeCr can be produced by the silico-thermic reduction of chromite ore and concentrates or by the decarburisation of HC FeCr in an oxygen-blown converter. The silico-thermic route is more economic and therefore more important today for producing MC FeCr. This may be because of the low demand for MC FeCr compared to the high demand for HC FeCr. LC FeCr can be produced by the same process.