Hebei Messi Biology Co., Ltd. stated that at a certain temperature, when the brine concentration is low, the supersaturation of the ammonia precipitation reaction is relatively small, and the number of crystal nuclei formed is small, which is conducive to obtaining large-particle magnesium hydroxide precipitation. The magnesium oxide obtained after calcination has a large particle size and is not suitable for silicon steel grade magnesium oxide; when the brine concentration is high, the relative supersaturation of the magnesium precipitation reaction is large, and the number of crystal nuclei formed is more, which is conducive to obtaining fine-particle magnesium hydroxide precipitation. The magnesium oxide obtained after calcination has a small particle size and can meet the requirements of silicon steel grade magnesium oxide.
During the experiment, the brine concentration was determined to contain 413 mol/L of magnesium chloride (close to saturation), which is also conducive to the recovery of by-product ammonium chloride, because the concentration of ammonium chloride in the mother liquor after separating magnesium hydroxide is high. The gravity sedimentation method is used to roughly estimate the size of the particle size, that is, under the same conditions, the sedimentation rate of large particles is fast and the sedimentation rate of small particles is slow. As long as the sedimentation rate of the particle is measured, its particle size can be roughly known.
Magnesium hydroxide, also known as caustic soda, has the chemical formula Mg(OH)2, molecular weight 58.32, CAS number 1309-42-8, and is a white amorphous powder. It is insoluble in water; it dissolves in dilute acid and is easily soluble in ammonium salt solution. It has good dispersibility when added to the system, and can significantly improve the flame retardant, smoke suppression, and filling properties of the material. It is an excellent flame retardant for plastics and rubber products. It can also be used in the refining of electronics, sugar, etc., and as a thermal insulation material to manufacture other magnesium salt products.
Magnesium hydroxide can be used as an anti-caking agent, antacid, filter aid, antibacterial colorant, etc. in food. Pharmaceutical grade magnesium hydroxide can be used as a pharmaceutical excipient, pH adjuster, filler, neutralizer, heavy metal adsorbent, anti-caking agent, desulfurizer, etc.