4 results about "Sodium chromate" patented technology

The application relates to the technical field of electroplating, and discloses a chromium electroplating process for improving the hardness of a connector terminal, which comprises the following steps: performing surface pretreatment on the connector terminal, removing surface impurities through ultrasonic cleaning and micro-etching treatment; performing heating treatment on the connector terminal; performing electroplating treatment on the connector terminal by using an electroplating solution comprising trivalent chromium salt, boron nitride nanoparticles, ferroferric oxide nanoparticles, nickel ions, sodium dichromate and chromium alloy additives, so as to form a chromium plating layer; performing passivation treatment on the plating layer; performing low-temperature treatment on the plating layer; and spraying a protective layer on the chromium plating layer. Through the trivalent chromium salt and the sodium dichromate, the trivalent chromium salt is used to reduce hexavalent chromium ions into trivalent chromium, the toxicity of the hexavalent chromium is reduced, the sodium dichromate is used to provide a stable chromium source, the deposition of chromium elements in the electroplating process is ensured, the pollution of hexavalent chromium to the environment and the harm of hexavalent chromium to the health of operators are solved, and the environmental protection and safety of the electroplating process are improved.

The application discloses a method for preparing sodium chromate by high-temperature separation and recovery of chromium slag, and belongs to the technical field of sodium chromate separation and preparation. The process comprises the following steps: adding sodium carbonate with a molar ratio close to that of chromium into the chromium slag and stirring uniformly, then, passing in air and roasting to 1200 DEG C-1400 DEG C and keeping the temperature until the weight is no longer reduced, when the temperature reaches 1200 DEG C, collecting the condensed material volatilized, namely, sodium chromate. Since the volatilization temperature range of sodium chromate is relatively wide, and the sodiumized roasting high-temperature volatilization temperature section 1200 DEG C-1400 DEG C of the chromium-iron slag has only sodium chromate, the process heating parameters can be easily adjusted and industrial control can be realized. Therefore, the method for preparing sodium chromate by high-temperature separation of chromium based on the volatilization phenomenon of sodium chromate combines the advantages of the previous processes, and has the advantages of simple process, environmental protection and remarkable economic benefits.

This utility model discloses a treatment system for recovering industrial-grade sodium chromate from chromium-containing electroplating wastewater. The system is sequentially connected to a pretreatment system, an ion exchange system, an evaporation and concentration system, a purification system, and an evaporation and crystallization system. The pretreatment system removes suspended solids. The ion exchange system contains at least four ion exchange columns and an eluent tank; the coordinated operation of multiple columns ensures sufficient adsorption and elution of chromium, increasing the concentration of hexavalent chromium in the eluent, reducing the load on subsequent evaporation equipment, and shortening processing time. The evaporation and concentration system uses an MVR evaporator and integrates an online density meter. The purification system is equipped with a purification reaction vessel with a detachable pH meter probe, which can quantitatively remove sulfate, reducing the difficulty of salt separation and crystallization, increasing the number of mother liquor circulations, and thus improving the chromium recovery rate. The feed to the eluent tank allows for reasonable adjustment of the alkali dosage according to different concentrations of components, avoiding waste and reducing costs. The detachable pH meter probe facilitates maintenance, ensures accurate monitoring, and improves the stability of sulfate removal rate and the quality of sodium chromate products.

This invention provides a method for recovering vanadium, chromium, and sodium from a vanadium-chromium sodium salt solution: (1) Adjusting the pH value of the vanadium-chromium sodium salt solution, adding a chromium precipitation agent and performing a first hydrothermal reaction to obtain chromium hydroxide product and chromium precipitation mother liquor; sequentially performing a first washing and a first heat treatment on the chromium hydroxide product to obtain chromium oxide product; (2) Adjusting the pH value of the chromium precipitation mother liquor, adding a vanadium precipitation agent and performing a second hydrothermal reaction to obtain vanadium dioxide product and vanadium precipitation mother liquor; sequentially performing a second washing and a second heat treatment on the vanadium dioxide product to obtain vanadium pentoxide product; (3) Mixing the first washing residue from step (1), the second washing residue from step (2), and the vanadium precipitation mother liquor, and evaporating and crystallizing the resulting sodium-containing solution to obtain sodium carbonate product. This method avoids the introduction of sulfur and ammonia nitrogen from the source, generates no chromium-containing solid waste, and has a short process, clean process, and low energy consumption.