Stainless Steel Pollution
Coke and Steel
A major source of steel pollution lies not in the production of the steel itself but in a necessary ingredient in steel production: coke. Coke, a product of bituminous coal, is used as a fuel and reducing agent in the smelting of iron ore. Although it occurs naturally, natural coke is usually of insufficient quality for industrial use. Thus, coke must be manufactured. Its manufacturing process creates air pollution in the form of coke oven gas, naphthalene, ammonium compounds, crude light oil, sulfur and coke dust. The coke production process creates large amounts of water polluted by coke breezes–tiny coke particles–and other solid compounds. Although emissions from coke facilities are filtered, these pollutants still escape into the environment. As an essential part of the process, coke pollution must be considered steel pollution.
Furthermore, one must consider the mining of the bituminous coal used to create coke. Coal mining is responsible for the presence of large amounts of acidic pollutants in the water near mines (in addition to air pollution and ecosystem disruption). Water quality and agriculture are often deeply impacted by local coal-mining operations. Additionally, coal processing facilities create materials rich in iron sulfides that oxidize into sulfates, causing water to acidify. Coal pollution overlaps with steel pollution and must be considered part of the problem of steel pollution.
Sheets of stainless steel must often be softened through a heat treatment process called annealing. Annealing stainless steel leads to the presence of oxide scale deposits on the steel. These deposits are removed by treatment with nitric, hydrofluoric, and hydrochloric acids in a process known as pickling. The byproduct of pickling is highly acidic, a dangerous pollutant to groundwater.