- Sep 01, 2018 -
The pre-plating treatment process produces different pollutants, including organic substances such as acid, oil and fat, heavy metals, cyanide, suspended solids, phosphates and surfactants, chromic acid, hydrochloric acid, sulfuric acid, organic gases and dust. , containing heavy metals, scum of wool, residual acid, residual alkali and waste solvents.
The mechanical pretreatment does not produce chemical reactions such as metal ions, so it does not produce contaminants such as metal ions, but it generates dust such as silicon-containing metal and cloth, which is discharged to the outside with the exhaust system. In the rolling process, abrasive powder and metal powder are taken out with water.
In the degreasing step, a large amount of an organic solvent, a base, a builder, a complexing agent, a surfactant, or the like is used, and an acid-base wastewater containing an organic solvent, a residual alkali solution, an emulsion, and a fat saponification liquid is generally generated. In addition to the oil bath liquid has a certain life, when the impurity content reaches a certain level must be updated, the oil removal liquid contains a large amount of organic solvents, residual alkali liquid, emulsion and oil saponification liquid, etc., is the main source of electroplating wastewater COD.
The etching (rust removal, activation) process produces a large amount of acidic wastewater and acid waste gas, such as acid particles (particle diameter of 2.5 ~ 2.7μm), hydrogen chloride, hydrogen fluoride and sulfuric acid mist, etc., must be installed ventilation and treatment equipment. The etchant also has a certain life, and the etchant must be renewed when the metal ions accumulated in the solution reach a certain concentration. The etched waste liquid contains a large amount of metal ions and residual acid. Like the degreasing waste liquid, it belongs to hazardous waste. The waste category is HW17, which needs to be disposed of according to the national regulations.