Research Of Product Lightweight Magnesium Carbonate By Twice Carbonation With Powder Of Light-burned Dolomite

The demand of lightweight magnesium carbonate is increasing continuously,while our native lightweight magnesium carbonate productions trailed developed country because of lower production quality.So it has necessity of theoretical significance and application value to research the method of high quality of lightweight magnesium carbonate productions.In this research powder of light-burned dolomite was chosed as raw materials to prepare lightweight magnesium carbonate,then lightweight magnesium carbonate is prepared by latex with high activity and twice carbonation under normal pressure.The influencing factor,optimization technics conditions and reaction mechanism of twice carbonation for the prepare of lightweight magnesium carbonate from light-burned dolomite powder is discussed.Optimization technics conditions of assimilation:mean particle diameter of light-burned dolomite is 1.781am,T=70℃,assimilation time is 30min, deposition time is 24h;optimization technics conditions of twice carbonation is pH₁=10,pH₂=9,Pco₂₁=0.03MPa,Pco₂₂=0.1MPa,carbonation solution concentration is 25g·L^-1,stir speed is 400rpm;rod-like basic magnesium carbonate can be prepared at 50℃,and length is about 60μm,section diameter is about 2μm,MgO content is 41%,CaO content is 0.4%, brightness is 97.3.Recovery of lightweight magnesium carbonate is 54.3% (MgO content of product/MgO content of material).Flaky or roseleaf shape lightweight magnesium carbonate can be prepared at 60℃;spheric lightweight magnesium carbonate can be prepared at 70℃,and diameter is about 40μm.Pyrogenation temperature effect on pyrogenation speed and structure of magnesium bicarbonate solution.It is easier to form of flaky and spheric lightweight magnesium carbonate by two-dimensional nucleation or boost up binding force between molecule and molecule.When lightweight magnesium carbonate is prepared under normal pressure at 50℃,add no additive can bring reunite;add sodium citrate can improve grain distribute uniformity;add ethanol can reduce ratio of length to diameter;add magnesium chloride can increase crystal length.It is because the change of crystal behavior and supersaturation after add additive.We can get CaCO₃ from deposition of carbonation solution,and CaO content is 44.3%,MgO content is 6.6%.