2020-11-03
| The electroplating industry is an important processing industry and technological production technology with strong versatility, wide application, and cross-industry and cross-sectoral. Electroplating is a process that uses electrolysis to attach a metal film to the surface of metal or other materials, which can improve corrosion resistance, appearance decoration, conductivity, and wear resistance. Electroplating is widely used in machinery manufacturing industry, light industry, electronic and electrical industry, etc. Some special functional coatings can also meet the needs of national defense technology products. The basic process of electroplating is roughly pre-plating, electroplating, and post-plating. The pretreatment of plating is mainly mechanical polishing, polishing, degreasing, acid or alkaline oxidation and other steps. Electroplating refers to the process of depositing metal on the workpiece through direct current electrolysis in a solution containing metal main salts and conductive salts, complexing agents, and additives. Generally, zinc, cadmium, copper, nickel, chromium, tin, and other single metals are used. Coating or copper-based alloy, lead-based alloy, nickel-based alloy and other alloy coatings. Post-plating treatment is mainly the cleaning process after electroplating is completed. This process will produce a large amount of electroplating wastewater, such as cyanide wastewater, chromium wastewater, cadmium wastewater, copper wastewater, zinc wastewater, acid-base wastewater, etc. The electroplating wastewater treatment process has different treatment methods according to the type of wastewater. The treatment of electroplating wastewater containing cyanide mainly uses sodium hypochlorite and chlorine dioxide to oxidize and decompose cyanide. After chromium-containing wastewater and zinc-containing electroplating wastewater are treated with reagents to reduce hexavalent chromium and zinc, the pH is adjusted to remove precipitation. The treatment of electroplating wastewater containing cadmium is to add polyferric sulfate under alkaline conditions to form a precipitate with cadmium and then remove it. The treatment of copper-containing electroplating wastewater mainly uses ion resin exchange to remove copper ions by exchange. According to the regulations of the pollution discharge permit for the electroplating industry, the electroplating wastewater sampling point is set at the discharge outlet of the workshop or the discharge outlet of the workshop treatment facility, and the sampling frequency is determined by the production cycle. If the production cycle is less than 8 hours, collect once every 2 hours; if the production cycle is longer than 8 hours, collect once every 4 hours. There are a total of 19 indicators for electroplating wastewater monitoring. They are total chromium, hexavalent chromium, total mercury, total cadmium, total lead, total copper, total nickel, total zinc, total silver, tin, aluminum, iron, total metal (refers to total copper, total nickel, total chromium and total The sum of the concentration of total zinc), pH, COD, total cyanide, fluoride, phosphate, suspended solids. Among them, 13 items are metallic metal pollutants and 6 items are non-metallic pollutants. |
浙公网安备 33022502000282号
浙公网安备 33022502000282号
