Feasibility study of metals recycling from nitric-hydrofluoric waste pickle baths

In this paper the feasibility of the recovery of the metals from stainless steel waste pickle baths by precipitation is studied. Precipitation is the easiest way to recover the metal content of the waste but the filter cakes obtained need a previous treatment step to be recycled. Precipitating conditions are optimized to obtain a solid with a composition that allows recycling in an electric arc furnace after thermal and mechanical treatment. Filter cake washing, thermal removal of impurities, metal compounds reduction, and solids briquetting are also studied. As a result, an overall method is proposed, consisting of precipitation and briquetting, giving products with adequate mechanical properties and composition.