Technology Development on Heavy Metal-contained Sludge Reduction and Resource Recovery on Stainless Steel Cold-rolled Mixed Sludge

摘要

Based on characteristics of stainless steel cold-rolled products pickling wastewater, a new process route with advantages of sludge originally reduction, wastewater two-stage treatment, Heavy metal-contained sludge and calcium-salt sludge separately recovery is developed. As 2 waste-water treatment stations operation results have shown, during the passed 6 years, annual sludge reduction ratios (per tons product) reach 43.64% and 50.29% respectively, realizing 105.6 thousands tons of sludge reduction effect and 68.04 millions CNY economic benefits. After two-stage process treatment, effluent water can reach emission standards steadily, Fe, Cr and Ni total contents in the front-part heavy-metal sludge increase from 10% to 30～40% compared with that of one-stage wastewater traditional treatment process, with dramatically decrease of F and S impurities content, therefore it can be used as ferric-contained sludge; while among the post-part calcium-salt sludge, F and S recovery ratios reach 20～40%, with Fe, Cr and Ni total content falls below 3%, therefore it can be used as fluorgypsum or fluorite. Since this technology fit the trend of hazardous waste original reduction and resource categorized recycle, it has a broad application prospect in stainless steel enterprise.