Process and apparatus for the low temperature recovery of ferrous chloride from spent hydrochloric acid pickle liquors

摘要

Processes and apparatus for the closed-loop regeneration of spent hydrochloric acid pickle liquors that have been used to pickle ferrous metals by recovering ferrous chloride from the spent pickle liquors at very low temperatures. The process includes maintaining the hydrochloric acid and iron concentrations within the spent pickle liquor at levels that will prevent the liquor from freezing when cooled to about -10 degrees Fahrenheit and that will permit the formation of ferrous chloride crystals within the spent pickle liquor when the liquor is cooled below about +18 to 20 degrees Fahrenheit and to about -10 degrees Fahrenheit. The ferrous chloride crystals formed at such low temperatures are then removed from the pickle liquor, which then permits reuse of the free hydrochloric acid remaining within the thus regenerated pickle liquor in normal pickling operations.