Sodium cyanide is a poisonous compound with the formula NaCN. It is a white, water-soluble solid. Cyanide has a high affinity for metals, which leads to the high toxicity of this salt. Its main application, in gold mining, also exploits its high reactivity toward metals. It is a moderately strong base. When treated with acid, it forms the toxic gas hydrogen cyanide.

Sodium cyanide, NaCN, is a cyanide salt that is a white, deliquescent, crystalline powder and is soluble in water. The specific gravity is 1.6, which is heavier than water. Sodium cyanide is toxic by inhalation and ingestion, with a TLV of 4.7 ppm and 5 mg/m3 of air. The target organs are the cardiovascular system, central nervous system, kidneys, liver, and skin. Reactions with acids can release flammable and toxic hydrogen cyanide gas. Cyanides are incompatible with all acids. The four-digit UN identification number is 1689.The NFPA 704 designation is health 3, flammability 0, and reactivity 0. The primary uses are in gold and silver extraction from ores, electroplating, fumigation, and insecticides.

Application

Sodium gold cyanide

Sodium cyanide is used mainly to extract gold and other precious metals in mining industry. This application exploits the high affinity of gold(I) for cyanide, which induces gold metal to oxidize and dissolve in the presence of air (oxygen) and water, producing the salt sodium gold cyanide (or gold sodium cyanide) and sodium hydroxide:

4 Au + 8 NaCN + O2 + 2 H2O → 4 Na[Au(CN)2] + 4 NaOH

A similar process uses potassium cyanide (KCN, a close relative of sodium cyanide) to produce potassium gold cyanide (KAu(CN)2). Few other methods exist for this extraction process.

Technical Specification

Physical Properties: