Copper slag is a by-product of copper extraction by smelting. During smelting, impurities become slag which floats on the molten metal. Slag that is quenched in water produces angular granules which are disposed of as waste or utilized as discussed below.
Slag from ores that are mechanically concentrated before smelting contain mostly iron oxides and silicon oxides.
Copper slag is mainly used for surface blast-cleaning. Abrasive blasting is used to clean and shape the surface of metal, stone, concrete and other materials. In this process, a stream of abrasive grains called grit are propelled toward the workpiece. Copper slag is just one of many different materials that may be used as abrasive grit. Rate of grit consumption, amount of dust generated, and surface finish quality are some of the variables affected by the choice of grit material.
The blasting media manufactured from copper slag brings less harm to people and environment than sand. The product meets the most rigid health and ecological standards.
Copper slag can be used in concrete production as a partial replacement for sand. Copper slag is used as a building material, formed into blocks. Such use was common in areas where smelting was done, including St Helens and Cornwall in England. In Sweden (Skellefteå region) fumed and settled granulated copper slag from the Boliden copper smelter is used as road-construction material. The granulated slag (<3 mm size fraction) has both insulating and drainage properties which are usable to avoid ground frost in winter which in turn prevents pavement cracks. The usage of this slag reduces the usage of primary materials as well as reduces the construction depth which in turn reduces energy demand in building. Due to the same reasons the granulated slag is usable as a filler and insulating material in house foundations in a cold climate. Numerous houses in the same region are built with a slag insulated foundation.
- ISO 11126-3:1993 Preparation of steel substrates before application of paints and related products -- Specifications for non-metallic blast-cleaning abrasives -- Part 3: Copper refinery slag: Preparation of Steel Substrates Before Application of Paints and Related Products.
- Ferguson, John (1996). "The Copper Slag Blocks of Hale" (PDF). Mining History. Peak District Mines Historical Society. 13 (2).
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