Chrome plating on chrome rods is also called "hard chrome plating or wear-resistant chrome". The chromium plating layer has a very high hardness, and its hardness can vary within a wide range (HV400MPa ~ 1200MPa) depending on the composition of the plating solution and process conditions. The chromium plating layer has good heat resistance. When heated below 500°C, its gloss and hardness will not change significantly. The friction coefficient of the chromium plating layer is small, especially the dry friction coefficient, which is the lowest among all metals. Therefore, the chromium plating layer has good wear resistance. Chromium plating has good chemical stability and does not react with alkali, sulfide, nitric acid and most organic acids. In the visible light range, the reflective ability of chromium is about 65%, which is between silver (88%) and nickel (55%). It is better than silver and nickel because chromium does not discolor and can maintain its reflective ability for a long time when used. . Since the chromium plating layer has the above-mentioned excellent properties, it can greatly extend the service life of the workpiece. Therefore, the chrome plating process of chrome plated rods has been widely used to this day. The generation of electroplating wastewater is mainly divided into two categories: pre-treatment rinsing wastewater before electroplating and post-plating cleaning wastewater after electroplating. For chromium plating of chromium-plated rods, the main pollutants in the pre-treatment rinse wastewater are pH, COD and petroleum, without heavy metal pollution; the main pollutants in the post-plating cleaning wastewater are Cr6+ and Cr3+, which are the main factors causing heavy metal pollution. At present, domestic chromium-containing wastewater basically adopts terminal chemical treatment method. Although it can meet the discharge standards, it cannot reduce the amount of electroplating liquid and the discharge of wastewater from the source. The general idea of ??this study is to change the "bath bath" of the workpiece after electroplating into a "shower". By using "aerosol spray" on the workpiece, the water consumption is only 5% to 8% of the original one. At the same time, because the electroplating liquid elements in the washed waste liquid are high, an atmospheric evaporation concentration device is used to concentrate the chromium-containing rinse water and reuse it directly to the electroplating tank, thereby achieving zero discharge of chromium-containing cleaning water and effectively avoiding environmental pollution. contamination risk. In addition, the biggest difference compared with traditional chemical methods is that chromium-containing sludge and residues are not formed, thus avoiding the harm of such substances to the environment and humans. Zero discharge of chromium-containing wastewater is a systematic work, involving equipment, technology, management and other aspects, and requires comprehensive analysis and research. Based on the technological transformation of chromium plating production and the practice of clean production audit work in recent years, and combined with the current technical management level of the domestic electroplating industry, the author attempts to conduct some research and analysis on the clean production measures for zero discharge of chromium-containing wastewater in chromium plating of chromium-plated rods, and through systematic implementation The environmental strategy of pollution prevention strives to improve the extensive processing methods that are still common in chromium plating of chrome-plated rods, and achieve the expected goals of "energy saving, consumption reduction, pollution reduction, and efficiency improvement".

1. Feasibility analysis of zero discharge of chromium-containing wastewater in the production of chromium-plated rods. The electroplating industry is an important processing industry in my country and is widely distributed in various industries. According to statistics, 33.8% of electroplating enterprises are located in Machinery manufacturing industry, 20.2% is distributed in light industry, 5% to 10% is distributed in electronics industry, and the rest is mainly distributed in aviation, aerospace and instrumentation industry. Chromium plating occupies an extremely important position in the electroplating industry and is a special coating among electroplated single metals. The chromium plating layer is silver-white with a bluish tint and has high hardness and wear resistance. For the steel substrate, the chromium plating layer is a cathodic plating layer. Because metal chromium has a strong passivation ability and can easily form a thin, dense oxide film in the air, the chromium plating layer has better corrosion resistance and shows the characteristics of precious metals. The uses of chrome plating can be divided into two categories: decorative chrome plating and hard chrome plating. The former usually requires an intermediate coating as a base. The coating is thin and can make the coating blue and white. It has a beautiful appearance and plays a decorative role, so it is named decorative chrome plating. The latter coating is thicker and has higher hardness. Because of its good heat resistance, wear resistance and corrosion resistance, it is often used as wear-resistant coating and repair coating. It is called hard chromium plating and is widely used in engineering machinery, Mining machinery, automobile shock absorbers, dump truck lifting cylinders and hydraulic tools and many other fields. This study mainly focuses on chromium plating of chromium-plated rods, which is hard chromium plating (also known as "wear-resistant chromium").

2. Improve process control: Transforming manual operation into an automatic (or semi-automatic) production line can effectively reduce the phenomenon of wastewater running, emitting, dripping and leaking, and avoid insufficient residence time in the recycling process caused by manual operation. Manual flushing leads to water waste and other irregular operations.