How to make the calcium carbonate powder?Posted: 2019-07-22

  • The preparation method of calcium carbonate is divided into physical method and chemical method. The calcium carbonate prepared by the physical method is called heavy calcium carbonate(ground calcium carbonatebecause of its large specific gravity, and the calcium carbonate prepared by the chemical method is called light calcium carbonate or precipitated calcium carbonate. When the size of the calcium carbonate particles reaches 100 nm or less, it is called nano calcium carbonate.

    The physical method for calcium carbonate powder making

    The physical method refers to a method in which no chemical reaction occurs from the raw material to the entire preparation process of the particles, that is, a method of mechanically pulverizing natural limestone or attapulgite having a high calcium carbonate content to obtain a calcium carbonate product. However, it is quite difficult to pulverize to 1 μm or less with a pulverizer, and it is possible to achieve 0.1 μm or less only by a special method and machine.

    For GCC powder making,there are three kinds of grinding mills can be recommended:

    HGM micro powder grinding mill: 200-2500 mesh (75-5 micron) calcium carbonate powder making, with capacity 0.5-45 t/h

    YGM high pressure Raymond grinding mill: 20-325 mesh(0.613-0.033 mm) calcium carbonate powder making,with capacity 1-25 t/h

    CLUM ultrafine powder vertical grinding mill: 400-3000 mesh (D97 less than 3000 mesh, D50 less than 2 micron) calcium carbonate powder making, with capacity 3-18 t/h

    calcium carbonate grinding mills

    The chemical method for calcium carbonate powder making

    The chemical method includes a carbonization method and a precipitation reaction method.

    The precipitation reaction method refers to a method of reacting a water-soluble calcium salt such as calcium chloride with a water-soluble carbonate such as ammonium carbonate and sodium carbonate under suitable conditions to obtain calcium carbonate. This method can control the concentration of the reactants and the supersaturation of calcium carbonate, and add appropriate additives to obtain amorphous calcium carbonate having a spherical shape, a very small particle diameter, a large specific surface area, and good solubility.

    Carbonization is a common method for the preparation of nano-CaCO3 by chemical methods. It is made from high quality limestone and calcined. CaO and CO2 are produced. The calcium oxide is digested with water to form calcium hydroxide (Ca(OH)2 emulsion. Then, the carbon dioxide gas generated by the calcination process is introduced, and an appropriate crystal form controlling agent is added to carbonize to the end point to obtain the desired crystal form of calcium carbonate. The slurry is further dehydrated, dried, sieved, and surface treated to obtain a nano calcium carbonate product.

    Preparation of hollow spherical calcium carbonate

    An aqueous solution of 20 g/L polyvinylpyrrolidone (PVP) was accurately prepared. Take out two copies of PVP (20
    mL solution was added to CaCl2 solution (0.1 mol/L, 50 mL) and Na2CO3 solution (0.1)
    In mol/L, 50 mL), the mixture was stirred vigorously and reacted in a water bath at 20 ° C for 0.5 h. Dodecylsulfonic acid
    A sodium (SDS) aqueous solution (0.05 mol/L, 20 mL) was added to the above Na2CO3 solution for 0.5 h. The above CaCl 2 solution was quickly poured into a Na 2 CO 3 solution under stirring, and subjected to a water bath at 20 ° C for 1 hour under stirring, and the stirring speed was maintained at 200 rpm. Inside the spatial network structure, calcium carbonate crystals nucleate and grow. The white precipitate was separated from the mother liquor, and the obtained product was filtered, washed with absolute ethanol and distilled water, and then placed in an oven at 80 ° C for 24 hours.

    Preparation of butterfly calcium carbonate

    An aqueous solution of 0.2 g of sodium polyacrylate (PAAS) was accurately prepared. Add it to the CaCl2 solution
    (0.1 mol/L, 50 mL), vigorously stirred, and reacted in a water bath at 80 ° C for 0.5 h. The above mixed solution was quickly poured into a Na2CO3 solution (0.1 mol/L, 50 mL) under stirring, and reacted in a water bath at 80 ° C for 3 h under stirring. The stirring speed was maintained at 200 rpm, and the white precipitate was separated from the mother liquid to obtain a product. After filtration, anhydrous ethanol and distilled water were repeatedly washed and dried in an oven at 80 ° C for 24 hours.

    1. Carbonization method
    Calcining raw materials such as limestone to produce lime (the main two components are calcium oxide) and carbon dioxide and then adding water to digest the lime to form lime milk (the main component is calcium hydroxide) and then pass carbon dioxide to carbonized lime milk to form calcium carbonate to settle the final calcium carbonate. Light calcium carbonate is obtained by dehydration, drying and pulverization.

    2. Calcium chloride method
    Calcium carbonate precipitation can be formed by adding calcium chloride to an aqueous solution of soda ash.

    3. Causticization subtraction
    In the process of producing caustic soda (Na0H), by-product light calcium carbonate can be obtained. Calcium carbonate precipitation can be formed by adding slaked lime to an aqueous solution of soda ash, and at the same time, an aqueous solution of caustic soda is obtained. Finally, the calcium carbonate precipitate is dehydrated, dried and pulverized to prepare light calcium carbonate.

    4. Calcium method
    The hydrated lime is treated with hydrochloric acid to obtain a calcium chloride solution. The calcium chloride solution is carbonized with carbon dioxide after inhaling chlorine gas to obtain calcium carbonate precipitation.

    5. Solvay method
    In the process of producing soda ash, permeate calcium carbonate can be obtained as a by-product. The saturated brine is carbonized with carbon dioxide after inhaling ammonia gas to obtain a heavy alkali (sodium hydrogencarbonate) precipitate and an ammonium chloride solution. Calcium chloride aqueous solution is obtained by adding lime milk to the ammonium chloride solution, and then carbonizing it with carbon dioxide to obtain calcium carbonate precipitation.

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