Extraction of Silver from Argentite Ore

Introduction:
Silver is a precious metal that has been used for various purposes for centuries. It is found in the earth's crust in the form of minerals such as argentite and galena. Silver is extracted from these ores by a variety of methods, including smelting and cyanide leaching.

Argentite Ore:
Argentite is a silver sulfide mineral with the chemical formula Ag2S. It is the most important ore of silver and is found in veins associated with other sulfide minerals. The silver content of argentite ranges from 30 to 87 percent.

Extraction Process:
The extraction of silver from argentite ore involves two steps:

Step 1: Conversion of argentite to silver sulfide
The ore is first roasted in air to form silver sulfide (Ag2S). Roasting involves heating the ore in the presence of oxygen to remove impurities and moisture.

2Ag2S + 3O2 → 2Ag2O + 2SO2

Ag2O + S → Ag2S

Step 2: Extraction of silver from silver sulfide
The silver sulfide is then leached with a solution of sodium cyanide (NaCN) to form a soluble complex, sodium dicyanoargentate.

Ag2S + 4NaCN → 2Na[Ag(CN)2] + Na2S

The complex is then treated with zinc dust to precipitate the silver metal.

2Na[Ag(CN)2] + Zn → 2Ag + Zn(CN)2 + Na2[Cn]

The silver metal is then purified by electrolysis or by the Parkes process, which involves the removal of copper and other impurities.

Conclusion:
Argentite is the most important ore of silver, and the extraction of silver from argentite is a complex process that involves several steps. However, with advances in technology, the process has become more efficient, and silver is now extracted from argentite ore on a large scale.