Copper slag is a by-product created during the copper smelting and refining process. As refineries draw metal out of copper ore, they produce a large volume of non-metallic dust, soot, and rock. Collectively, these materials make up slag, which can be used for a surprising number of applications in the building and industrial fields.
This material represents a popular alternative to sand as a blasting medium in industrial cleaning. Using blasting or high-pressure spraying techniques, companies can use copper slag to clean large smelting furnaces or equipment. Slag blasting is also used to remove rust, paint, and other materials from the surface of metal or stone. This helps to prep the surface for painting, or simply to remove unwanted finishes or residue.
Copper slag has also gained popularity in the building industry for use as a fill material. Unlike many other fill materials, it poses relatively little threat to the environment. This means it can be used to build up the earth to support roads, buildings, or other surfaces.
Contractors may also use copper slag in place of sand during concrete construction. The slag serves as a fine, or binding agent, which helps hold the larger gravel particles within the concrete together. When used in this manner, the slag helps to improve the properties of the concrete, and also serves as a form of recycling.
One of the primary advantages to copper slag is the low risk it poses to health and the environment. Silica sand, which represents the most popular blasting medium and concrete fine currently in use, poses serious health risks when inhaled. It may also contribute to pollution and other environmental concerns.
Copper slag also has a high strength-to-weight ratio, making it an effective option in concrete, or as a fill material under the roadway. When added to concrete, it makes the paved surface less porous, which minimizes problems with moisture and freezing. It also makes concrete more fire resistant, and helps to slow the spread of heat and flames.
This material also has several limitations that users should be aware of before using copper slag. Some versions may contain heavy metal traces, which can contribute to air and water pollution. It's commonly classified as hazardous waste due to this risk. Another issue to consider is the shear volume of slag produced during copper refining. Typically, refineries end up with two units of slag for every one unit of copper produced during smelting.