Slaglast

Slaglast is a term used in metallurgy to denote a dense, glassy crust that forms on cooling slag during metal-smelting operations. It describes the most consolidated portion of slag that remains after less-compact fractions have separated or been removed. The term is not universally standardized and can vary in meaning between facilities, but it is commonly associated with the solidified layer that adheres to the bottom of a slag pool or to the inner surfaces of slag containment structures.

Formation and composition: Slaglast develops as molten slag starts to solidify when heat extraction slows or changes in temperature occur. It may crystallize into a hard, glassy crust enriched in silicates and metal oxides. Its exact mineral composition depends on the feedstock, fluxes, and smelting conditions, and it often contains small inclusions of metallic or mineral phases carried over from the furnace.

Properties and identification: Slaglast is typically darker in color and more dense than surrounding slag, with a hard, abrasive texture. It may form a continuous layer on the surface or settle as a dense pocket at the bottom of slag heaps. The crust can be distinguished from other slag forms by its glassy microstructure and higher density.

Uses and handling: Processed slaglast can be crushed and used as road-base aggregate, concrete aggregate, or as a refractory filler after sufficient metal removal and safety processing. Its reuse potential depends on its chemical stability and the absence of hazardous metal leachates, which must be assessed during disposal or recycling.

Environmental considerations: Slaglast handling requires management to prevent leaching of contaminants and to meet local regulatory requirements for industrial byproducts. Stabilization, washing, and proper containment are common practices before reuse or disposal.

See also: slag, metallurgical byproducts, slag heap.