US Patent 10526684 Process for recovering components from pickling acid residue

A novel process for treating and recovering valuable metals and other components from pickling acid residue (PAR) has been developed. The metals and other components are recovered by neutralizing the pickling acid residue using a magnesium compound or a mixture of magnesium compounds, and separating components of the resulting mixture (metals and sulfates) into products that can be reused, such as magnesium sulfate, nickel sulfate, iron and chromium phosphate, or various metal hydroxides or oxides.