Hazardous chemicals in mining

Process plants and refineries commonly contain a wide range of hazardous chemicals, including:

• acids such as sulfuric acid, hydrochloric acid and nitric acid, frequently used to dissolve metals in ores
• caustic soda (sodium hydroxide), used as a reagent to dissolve bauxite in alumina refineries, or to neutralise acid process streams and wastes
• sodium cyanide, used on most gold mines to help process the ore.

Xanthates (used as flotation chemicals), solvents and compressed gases may also be present. Chemicals such as sulphur dioxide, hydrogen sulphide, carbon monoxide and oxides of nitrogen can be produced during the processing of mineral ores. Sodium cyanide must be carefully managed to reduce worker exposure through direct contact or hydrogen cyanide gas.

Mine site laboratories usually have the widest variety of chemicals on a mining operation, though typically in small quantities. Acids used to break down materials carry the greatest risk, but all chemicals must be handled with care.

Fire assay laboratories may use large amounts of lead reagents. The sample preparation area must manage risks from respirable crystalline silica dust, fibres and fumes produced during sample preparation.

Access to the gold room is restricted for security reasons. Common hazardous chemicals found include acids, cyanide and fluxes. Ammonia from electrowinning and lead, arsenic or mercury from smelting gravity gold may also need to be managed.

Mine site workshops usually cover light and heavy vehicles, as well as mechanical and electrical areas. Most oils, greases and lubricants present a low hazard. However, cleaning solvents, spray painting chemicals and dust from grinding and sandblasting must be controlled.

Fumes from welding, cutting, or vehicle exhaust can be hazardous, especially in enclosed areas.

Many mines operate reverse-osmosis or other water-treatment plants. Workers must manage exposure to hazardous chemicals such as acids and chlorine.