The physical properties of lithopone:
1, traits: Lithop powder is also known as zinc bismuth white, English name Lithopone, is a non-toxic white powder, is a mixture of zinc sulfide and barium sulfate. It is easily oxidized in the air and deteriorates after moisture. BaSO4 has a rhombohedral crystal structure, and ZnS has a cubic or hexagonal crystal structure.
2. Relative density: 4.136～4.39. Among the commonly used white pigments, the relative density of lithopone is the smallest. Among the white pigments of the same quality, the surface area of titanium dioxide is the largest and the pigment volume is the highest.
3. Solubility: Insoluble in water, it will sink in the water.
4. Refractive index: 1.70~2.25
5, boiling point range (C): 1180 (sublimes)
6, specific gravity (water = 1): 4.0-4.3
7, oil absorption 10-12
8, pH 8-9.5
9. Good chemical stability, except for acid with pH<3
10. Particle size: The particle size distribution of lithopone is a comprehensive index, which seriously affects the properties of lithopone pigments and product application properties. Therefore, the discussion of hiding power and dispersibility can be directly analyzed from the particle size distribution.
Lithopone chemical properties
Lithopone is insoluble in water, and it liberates hydrogen sulfide from acid action. It does not work with hydrogen sulfide and alkali. It has good heat resistance, can improve weather resistance, prevent algae, reduce cost and its whiteness with excellent shielding power. . Lithopone is a white pigment, a mixture of zinc sulfide and barium sulfate, the main component of which is ZnS 30% / BaSO4 70% or ZnS 60% / BaSO4 40%.
1. Lide powder (zinc bismuth white) Synthesis method:
The precipitate obtained by reacting zinc sulfate and barium sulfide solution is filtered, dried and pulverized, then calcined to red heat, and poured into water to be quenched.
1. Using roasting and leaching.
The reaction equation is as follows:
Mixing natural barite containing barium sulfate greater than 95% with anthracite in a ratio of 3:1 (mass)
After being pulverized to a diameter of about 2 cm or less, it enters the reduction furnace, and the front stage of the furnace temperature is controlled by 1000 to 1200 ° C, the latter stage is 500 to 600 ° C, and the reduction furnace is rotated at a speed of 80 s per revolution, and the reaction conversion rate is 80% to 90%. The obtained barium sulfide enters the leaching device, and the controlled temperature is above 65 °C, and the content of barium sulfide is 70.1%, and then enters the clarification tank. After clarification, the zinc sulfate reaction is added to control the zinc sulfate content to be greater than 28%, and the pH is 8-9. A mixture of barium sulfate and zinc sulfide having a density of 1.296 to 1.357 g/cm3. The reaction solution is subjected to pressure filtration through a plate frame to obtain a cake-like lithopone powder having a water content of not more than 45%, which is calcined in a dry roasting furnace to change the crystal form of the lithopone, and then acid-washed with sulfuric acid at a temperature of 80 °C. Finally, it is washed with water, reinforced with coloring agent, pressure filtration, drying and milling.
2 barite calcination method to prepare barium sulfide solution
The sulfuric acid and zinc oxide are reacted, purified by adding potassium permanganate and zinc powder, and compressed to obtain a zinc sulfate solution. Then, the prepared barium sulfide solution is mixed and subjected to a metathesis reaction to obtain a mixture of zinc sulfide and barium sulfate, and then the precipitate is subjected to pressure filtration, calcination, wet grinding, drying, and pulverization to obtain a zinc white product. Its reaction equation is: ZnSO4+BaS→ZnS+BaSO4.
3 The calcined product obtained by the ordinary zinc bismuth method is slurried into a slurry, which is sequentially treated with sodium silicate, aluminum sulfate or sodium aluminate and a surfactant, and then filtered, washed, dried and pulverized. Just fine.
2. Lide powder risk and emergency measures:
Hazard: It is highly toxic to aquatic organisms and prevents release into the environment.
1 Ingestion: Contact a doctor or poison center. If the patient is awake and takes more than 15 minutes at the doctor, induce vomiting. Rinse with plenty of water.
2 Eyes: Rinse with running water (15 minutes). Seek medical attention.
3 skin: cover the body with water. Remove contaminated clothing and rinse with soap and water. Seek medical attention.
4 Inhalation: Clean the nasal cavity and rinse the mouth with water.
3. Lide powder (zinc bismuth) Storage method:
Store in a cool, ventilated, dry warehouse. Should pay attention to heat and moisture. Store separately from acid products. Lightly load and unload during handling to prevent damage to the packaging. Packed in woven bags lined with polyethylene plastic bags, each bag has a net weight of 25kg. Store in a cool, ventilated, dry warehouse. Should pay attention to heat and moisture. Store separately from acid products. Lightly load and unload during handling to prevent damage to the packaging. In case of fire, use water and various fire extinguishers to save.
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