Calcium-silicon

a ferroalloy containing 23–32 percent Ca and 2–4 percent Fe (the remainder is Si); it is smelted by carbon reduction of lime and quartzite in ore heat-treating furnaces. Ferrocalcium-silicon, containing 10–20 percent Ca and up to 25 percent Fe (the calcium costs are lower than that in calcium-silicon), is obtained by adding iron chips to the charge using the carbon-reduction or silicothermic process. Both alloys are used as deoxidizers in the smelting of steel.