According to Hebei Messi Biology Co., Ltd., magnesium carbonate is a white, odorless powder with two common forms: amorphous powder and monoclinic crystal. Due to its special structure and properties, magnesium carbonate is widely used in medicine, cosmetics, rubber industry, printing industry and other fields. Industrial-grade magnesium carbonate can be used as an excellent filler and reinforcing agent for rubber products, and can also be used as a heat-insulating and high-temperature-resistant fireproof and thermal insulation material.
Pharmacopoeia-grade magnesium carbonate can be used as an additive for beverages and daily chemical products, as well as for gastric acid neutralization inhibitors, etc. Add appropriate amount of additives to the magnesium bicarbonate solution, and obtain magnesium carbonate whiskers of different specifications by controlling the crystallization conditions of the magnesium carbonate. There is no bibliographical report on spherical and radial magnesium carbonate and its preparation method.
The purpose of this invention is to provide a kind of preparation method of spherical, radial magnesium carbonate. Take soluble magnesium salt and soluble carbonate as raw material, take surface-active substance as additive, in aqueous solution system, control reaction temperature between 15～75 ℃, react 2～20min under agitation; The precipitation after reaction is finished standing still after 1～6 days washs, dries, obtains spherical, radial magnesium carbonate product.
When preparing magnesium carbonate, first soluble magnesium salt, soluble carbonate, surface active substance are mixed with concentration respectively and be the aqueous solution of 0.5mol/L～1.5mol/L, 0.5mol/L～2mol/L, 2mmol/L～2mol/L, then the aqueous solution of soluble magnesium salt solution, soluble carbonate solution, surface active substance are mixed, react under stirring. When the surface-active substance is a polymer, it is prepared into an aqueous solution with a concentration of 1～5g/L. The amount of soluble magnesium salt and soluble carbonate is controlled between 1:2~1:0.5, and the concentration of surface active substance in the whole reaction system is 2mmol/L~0.5mol/L. When the surface-active substance is a polymer, the concentration of the surface-active substance in the entire reaction system is between 0.1 and 1 mg/L.
There are two ways to mix the soluble magnesium salt solution, soluble carbonate solution and the aqueous solution of the surface active substance: first mix the soluble magnesium salt solution and the solution of the surface active substance, then add the soluble carbonate solution to the reactor simultaneously, and react under stirring; or add the soluble magnesium salt solution and the soluble carbonate solution to the aqueous solution of the surface active substance at the same time, and react under stirring. After the reaction was completed, the precipitate was allowed to stand for 1 to 6 days, and the combination of reslurry washing and leaching was adopted: first reslurry washing 1 to 3 times, and then rinsing with distilled water until chlorine radicals could not be detected in the washed water, and then rinsing with ethanol; finally drying at 15 to 75°C. The soluble magnesium salt used in the present invention is magnesium chloride, magnesium sulfate, magnesium nitrate or magnesium acetate; the soluble carbonate used is sodium carbonate, ammonium carbonate or potassium carbonate.
The morphology of magnesium carbonate can be controlled by changing the kind and consumption of surface active substance, changing the stirring speed of reaction solution: when surface active substance adopts sodium tartrate, sodium alginate, sodium silicate, SrCl2, CaCl2, MnCl2, any one in LiCl, when reaction stirring speed is controlled at 100～600rpm, the magnesium carbonate product obtained is spherical.
When surface-active material adopts any one in sodium lauryl sulfate, sodium lauryl sulfonate, cetyltrimethylammonium bromide, potassium hydrogen phthalate, sodium tartrate, sucrose, glucose, β-cyclodextrin, soluble starch, sodium citrate, polyacrylamide, glycerol, polyethylene glycol, ethanol, flocculant 1010f, flocculant 1019s, when the reaction stirring speed is controlled at 500～900rpm, the magnesium carbonate product obtained is radial.
Spherical, radial magnesium carbonate product prepared by the present invention, through XRD analysis and chemical analysis, its chemical formula is MgCO XH O, wherein x=2～5; Purity is between 95～99.9%. The appearance is fine sand, and the filtration performance is obviously better than that of ordinary magnesium carbonate, thus improving the problem of slow filtration of ordinary magnesium carbonate due to the fine particles. It can be used as an additive in industries such as plastics, rubber, and papermaking, and can also be used as an intermediate raw material for the preparation of high-purity magnesium oxide and other magnesium products.