Additives for light burned magnesia

After the reaction of pure aqueous solution and MgO, Mg (OH) 2 is in a loose state, so there is no practical value. In 1867, Swedish scholar Sorrell invented magnesia cement. The compressive strength and flexural strength of the cement in dry environment are almost the same as those of the ordinary cement. The compressive strength is 110MPa / 28d, and the flexural strength is 20MPa / 28d.


（1） Magnesium chloride hexahydrate (MgCl2 · 6H2O) has the same compressive and flexural strength as ordinary silica cement, but it can only be used in dry environment. Magnesium chloride hexahydrate, also known as chlorite, is soluble in cold water at 0 ℃, with a relative density of 1.56 and a melting point of 712 ℃ at a water-soluble ratio of 281g / 100g. When heated to 118 ℃, hydrolysis begins and decomposes into MgO and HCl at high temperature.


MgCl2·6H2O→Mg(OH)Cl+HCl+5H2O


Mg(OH)Cl→MgO+HCl


To the fourth water, the second water, the first water and anhydrous magnesium chloride, please refer to the brief introduction of magnesium chloride of Anmei Industrial Development Co., Ltd. Its content accounts for 15-20% of MgO


（2） Magnesium sulfate heptahydrate (MgSO4 · 7H2O) is a curing agent as well as a waterproof agent. Its molecular weight is 246.48 colorless crystal or powder. No bromine or bitterness. When it is dissolved in water at 250 ℃, it becomes anhydrous magnesium sulfate (MgSO4), and above 400 ℃, it is reduced to MgO. It is a reaction product of MgO and H2SO4. The content of MgO is 15-20%. The cost is higher than MgCl2 · 6H2O.


（3） Ferrous sulfate heptahydrate (FeSO4 · 7H2O) is a waterproof agent, light blue monocrystal, also known as alum with relative density of 1.898 (at 18 ℃), which is easy to melt in water and has natural production of alum. The dosage accounts for 3% of the total.


（4） Styrene butadiene rubber latex (SBR solid content ≥ 45%) is waterproof rubber latex, with the content accounting for 6-12% of the total volume.


（5） Chloroprene rubber latex, also known as chloroprene rubber latex, accounts for 6-12% of the most stable amount of waterproof rubber latex in magnesium oxide materials, and 1% of (ohch2ch2) 3N is added at the same time.


（6） Silica sol, styrene acrylic latex and butyronitrile latex can be used as waterproof latex, accounting for 6-12% of the total volume.


（7） SiO2 type additives account for 10-15% of the total volume.


（8） The content of urea formaldehyde resin and melamine is 2-3% of the total.


（9） Phosphoric acid (H3PO4), also known as orthophosphoric acid, is a better curing waterproof agent, accounting for 4% of the total content.


（10） The content of modified sodium silicate is 1-3% of the total content