Cadmium selenide sulfide (Cd2SeS)

The industrial production of general-purpose cadmium red often uses three methods: calcining, precipitation, calcining and hydrothermal methods. Special cadmium red is processed by a suitable method. Calcining method. Using cadmium carbonate, sulfur and selenium as starting materials, cadmium red is directly calcined. Reaction equation: CdCO3→CdO+CO2↑ 2CdO+S→2Cd+SO2↑Cd+S→CdS Cd+Se→CdSe nCdS+CdSe→nCdS·CdSe Operation method: put the raw materials in a mixing barrel or grinder with agitator Mix it evenly, put it in a converter or muffle furnace for calcination. The ratio of the charge and the calcination temperature determine the hue and characteristics of cadmium red. Cadmium red contains about 70% cadmium and different proportions of selenium. The content of selenium determines the color of cadmium red. It is the main factor for process control. The higher the selenium content, the darker the pigment red. Some side reactions also occur during calcination. For example, CdO is reduced by Se, part of S and Se are oxidized, and volatilized with SO2 and SeO2, and a small amount of CdS and CdSe are oxidized. Therefore, the actual ratio of S to Se is slightly higher than the theoretical calculation. excess. Precipitation-calcination method. First, cadmium salt (such as CdCO3) is reacted with sodium sulfide and hydrogen selenide (or sodium sulfide selenide) solution to form cadmium sulfide selenide (nCdS·CdSe) precipitate, and then the precipitate is calcined at high temperature to produce cadmium red. The calcination method is similar to the "calcination method" described above. According to the different starting materials for the manufacture of cadmium red, the precipitation-calcination method can be divided into insoluble cadmium salt method (such as cadmium carbonate method) and easily soluble cadmium salt method (such as cadmium sulfate method). Cadmium carbonate method. Using insoluble cadmium carbonate as raw material, cadmium red is prepared through precipitation and calcination processes. Reaction equation: Cd+2HCl→CdCl2+H2↑ CdCl2+Na2CO3→CdCO3↓+2NaCl Na2S+Se+2H2O→H2Se+S+2NaOH 4CdCO3+H2Se+2NaOH+3Na2S→3CdS+CdSe+4Na2CO3+2H2O Pour the measured hydrochloric acid and nitric acid from the storage tank into the acid hydrolysis tank, and simultaneously put in the metal cadmium flower, control the feeding rate and keep the reaction temperature at about 80-90°C. The generated cadmium chloride solution is pumped to the storage tank for later use. Adjust the density of cadmium chloride to 1.162g/cm3 and pump it to the synthesis tank. Dissolve sodium carbonate in water, send it from the dissolving tank to the high tank with a pump, and then add water into the preparation tank to adjust the density to 1.116～1.125g/cm3. Start the synthesis tank and stir, slowly add sodium carbonate solution, and react with cadmium chloride to immediately produce white cadmium carbonate precipitate. When the pH value is 8-9, the feeding is stopped, and the reaction is completed for about 30 minutes, and the cadmium carbonate slurry is obtained by draining water. The density of the purified sodium sulfide is adjusted to 1.134～1.143g/cm3, and the pump is sucked into the high-level metering tank from the storage tank, and then added to the selenium powder dissolution tank. Add metered selenium powder, stir and heat up to 70-80°C, and react until all selenium is dissolved. Pump the solution to the synthesis tank with a pump, and raise the temperature to 70~80°C to react with sodium carbonate to generate cadmium sulfide selenide co-precipitation. After rinsing, the precipitate is sent to the filter press for filtration, enters the drying box for drying, and then sent to the high-temperature converter for calcination for about 1 hour. The calcination temperature is controlled at 550～600℃. After the sample is compared with the standard color, it will be discharged and quenched. Then the calcined product is sent to a ball mill and water ball milling. After about 6-10 hours, the slurry is discharged, and the slurry is pumped into the rinsing bucket with a pump, and the soluble salts are washed away with water. After the sampling is qualified, it is sent to the filter for filtration. After the filter cake is dried in an electric drying oven, it is crushed by a pulverizer, and then enters the cyclone separator. The cadmium red product enters the packaging barrel from the lower part of the separator. The dust is processed by the top dust removal system. Cadmium sulfate method. Cadmium sulfate is a soluble salt that can directly react with sodium sulphide selenide to form cadmium sulfide and cadmium selenide precipitation. If a small amount of sodium hydroxide is added, it will not only help maintain the required pH value for the reaction, eliminate the influence of sodium sulfate neutral salt formation in the reaction, but also increase the utilization rate of selenium. Reaction equation: 2CdSO4+2Na2S+Se→CdS↓+CdSe↓+2Na2SO4+S↓ Operation method: first dissolve cadmium with 180g/L sulfuric acid, and add a little nitric acid to accelerate the dissolution. The generated cadmium sulfate is neutralized with lye, adjusted to pH=5.4-6.2, and filtered for use. Then prepare selenium and sodium sulfide to dissolve. Dissolve sodium selenide in water, add a metered amount of selenium powder, stir and heat until the selenium powder is completely dissolved. The double salt formed by selenium and sodium sulfide is very unstable, and selenium will precipitate after cooling. It is advisable to use a newly prepared sodium sulphide selenide solution. Heat the prepared cadmium sulfate solution to 75°C, slowly add it to the sodium sulphide selenide solution at about 70°C under stirring, control pH ≥8, after the reaction is complete, sprinkle and wash the precipitate three times, filter and dry to obtain Cadmium red semi-finished raw materials. After being crushed, the semi-finished material cake is calcined at 580-600°C. The optimized process is the same as the "cadmium carbonate method". To make cadmium red from cadmium sulfate, you only need to adjust the ratio of selenium to make other colors, such as cadmium red (contains Cd 69.42%, Se 16.30%, S 10.61%), cadmium violet (contains Cd 64.95%, Se 22.36%, S 10.23%), cadmium orange (Cd 70.83%, Se 13.20%, S 12.47%). This is because the solubility product of cadmium selenide is smaller than that of cadmium sulfide, and cadmium selenide is better than cadmium sulfide. The advantage of the method is that the process flow is shortened, and there is no unreacted cadmium carbonate residue in the cadmium red product. However, the uniformity and thermal stability of the cadmium sulfate method pigment particles are not as good as the cadmium carbonate method cadmium red. Hydrothermal. In addition to the high-temperature calcination process, hydrothermal leather shortens the process flow and reduces waste gas pollution. It is a relatively new process.

Cadmium red is widely used in industries such as enamel, ceramics, glass, coatings, plastics, art pigments, printing inks, papermaking, leather, colored gravel building materials and electronic materials. When used in polymers, cadmium pigments should be used in systems with low water absorption, because the water permeability in the medium will reduce the weather resistance of the pigment. The presence of titanium dioxide also reduces the lightfastness of the pigment. Cadmium red has better durability than cadmium yellow, and is suitable for coloring outdoor products, such as automotive coatings and high-grade baking paints. Cadmium red has lower natural hardness than other inorganic pigments and good friction. It can be used for gravure printing ink and PVC screen printing oil. In addition to mercury and cadmium red is not suitable for polycarbonate, cadmium red is suitable for almost all resins and plastics, such as ABS plastics, polyoxymethylene, acrylic, amino, fluoroplastics, nylon, polyamide, polycarbonate, low density or high density Polyethylene, polypropylene, polystyrene, soft or hard PVC, phenolic, urea melamine, epoxy, polyurethane, unsaturated polyester, organic glass, natural rubber and silicone rubber.

Molecular Weight:335.87
Hydrogen Bond Acceptor Count:2
Exact Mass:337.69472
Monoisotopic Mass:339.69532
Topological Polar Surface Area:1
Heavy Atom Count:4
Covalently-Bonded Unit Count:4
Compound Is Canonicalized:Yes