Process Name

Smelting Copper or Lead

Description

Lead and copper smelter workers are exposed to lead, arsenic, carbon monoxide, sulfur dioxide, and silica. [ILO Encyclo: Copper, Lead and Zinc Smelting and Refining] Copper smelting: After grinding the crushed ore, a slurry is formed to which flotation |"assists|" are added. The froth containing the copper is skimmed off, dewatered, and shipped to the smelter as a 16-32% concentrate. The concentrate contains to 0.001-6.7% arsenic, 0.003-1.3% lead, and 0.001-0.04% cadmium. The first step at the smelter is roasting, followed by smelting, converting, and refining. Smelting produces a Cu-Fe sulfide matte (35% Cu). Converting produces blister copper (98.5% Cu). Refining produces domestic copper (>99.5% Cu). The prominent exposures of concern are to silica dusts, metal fumes, sulfur dioxide, and carbon monoxide. Lead smelting: The crushed and ground ore, containing 3-8% lead, is concentrated by differential flotation. It is then pelletized with limestone, silica sand, and iron ore. The pellets are sintered to convert lead sulfide to lead oxide and release sulfur dioxide. Metallic lead is formed in the blast furnace and separated from slag by gravity. The slag is rich in zinc. Other metals recovered are antimony, tin, silver, and gold. Blast furnace exposures of concern include metal fume, carbon monoxide, sulfur dioxide, and arsenic. Lead is further refined in a reverberatory furnace or electrolytically using molten sodium hydroxide and sodium nitrate. [Burgess, p. 435-42]

Category

Industry

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Agents

Hazardous agents associated with this process: