spent pickle liquor

Spent pickle liquor is considered a hazardous waste by the EPA.

T82 Sludge from lime treatment of spent pickle liquor from steel finishing operations.

The following processes for the regeneration of HCl from spent pickle liquors have been adopted by the ferrous metals processing industry:

Pyrohydrolysis of hydrochloric spent pickle liquor from carbon steel pickling lines is a hydrometallurgical reaction which takes place according to the following chemical formulae:

Other hazardous wastes and hazardous recyclable materials imported included spent pickle liquors from metallurgical processes, contaminated soils and residues from oil refining.

The steel pickling industry has developed hydrochloric acid regeneration processes, such as the spray roaster or the fluidized bed HCl regeneration process, which allow the recovery of HCl from spent pickling liquor.

Spent pickle liquor, containing weak acids and iron compounds, is generally processed in an on-site acid regeneration plant that recycles the regenerated acid to the pickling operation and iron oxide to steel-making or sale.

Today hydrothermal hydrolysis, which operates at very low temperatures, consumes only a fraction of the energy other processes demand and produces virtually no emissions, is considered the most effective way to regenerate any given quantity of spent pickle liquor.