Extractive antimony metallurgy

Antimony is widely distributed in the earth's crust. Its main mineral species are stibine, by far the most widespread, and lead and copper sulfoantimonides. After a presentation of antimony's concentrative phenomena and geology, this article looks at its mineralurgy and extractive metallurgy, as well as its uses, toxicity and recycling. Two main types of antimony ore are distinguished: ores with predominantly stibine and complex ores of lead, zinc and copper, which incidentally contain stibine and sulfoantimonides. In industry, mineralurgy and extractive metallurgy methods are adapted to each of these ore types.

Stibine-dominant ores are processed to produce a stibine concentrate and, where the ores contain gold, a separately extracted gold concentrate. The stibine concentrate is then processed by pyrometallurgy to produce an antimony sulfide called crude, or an antimony metal called regule. Stibine hydrometallurgy enables the production of a soluble antimony salt from which antimony metal can be obtained, but is poorly mastered industrially.

From complex ores with accessory stibine, lead sulfide, zinc sulfide and possibly copper sulfide concentrates are produced separately. During these operations, antimony is found in the lead sulfide concentrate and, where applicable, in the copper sulfide. A pyrometallurgical treatment then results in the production of lead or copper blister containing antimony:

• Lead is purified in a series of pyrometallurgical operations. In one of these stages, the antimony is transformed into sodium antimonate, which, after reduction and refining, yields "regulator" grade antimony. Another method consists of electrolyzing the lead, producing anodic slurries which, after smelting, yield an antimonous lead;

• copper blister is refined by electrolysis. Antimony is found along with Te, Se, Ag, Au and Cu in copper electro-refining sludge. Its recovery is difficult and mostly abandoned.

Health risks are high, caused by inhalation of furnace dust or toxic gases emitted during the electro-refining of lead or copper.

Environmentally, antimony pollutes the atmosphere through dust and toxic gases, natural waters through soluble forms and soils through slow accumulation.

Most antimony is marketed as oxide or electrolytic antimony. Only a few large producers, including China, the world's leading producer, supply the world's needs.