Study On Preparation Process And Thermal Analysis Of Basic Magnesium Carbonate

Basic magnesium carbonate is the most common magnesium compound in industry.Because of its superior dispersion,high elastic modulus,good mechanical properties and filling properties,it is often used in flame retardant,medicine,food,electronics and military industry.Basic magnesium carbonate is a non-toxic and harmless substance.It only produces water and carbon dioxide when it is decomposed at high temperature,but no other pollutants are produced.It also absorbs a large amount of heat.Therefore,we prepared basic magnesium carbonate by liquid phase crystallization?stirring method and ultrasonic method?and carbon dioxide capture method,and studied the influence of temperature,time and other factors on the product morphology.1.Preparation of basic magnesium carbonate by liquid phase crystallizationIn this chapter,magnesium sulfate and sodium carbonate were used as raw materials.First,nesquehonite?MgCO₃·3H₂O?was produced by the double decomposition reaction,and then was pyrolyzed to form basic magnesium carbonate?4MgCO₃·Mg?OH?₂·4H₂O?.The liquid phase crystallization method includes stirring method and ultrasonic method.The effects of temperature,time,pyrolysis temperature and pyrolysis time on the morphology of basic magnesium carbonate were studied.The effects of stirring method and ultrasonic method on the morphology of nesquehonite and basic magnesium carbonate are discussed.The product morphology was studied by SEM,phase analysis was performed by XRD,and thermal analysis was performed by thermogravimetric analysis and differential scanning calorimetry.The results show that nesquehonite is rod structure and basic magnesium carbonate is sheet structure under stirring.When the double decomposition time for30 min,double decomposition temperature is 20?,and the pyrolysis time is 2 h,pyrolysis temperature is 130?,basic magnesium carbonate as the spherical morphology,surface plate shaped structure,similar to the petal shape spherical structure.Under ultrasonic radiation reaction,the generated nanoparticles structure of sanshui magnesium carbonate as irregular,and the pyrolysis under 95?to generate uniform size,spherical morphology rules basic magnesium carbonate,its diameter is about 10 microns,the surface plate shaped structure.To thermal analysis of product basic magnesium carbonate,research shows that basic magnesium carbonate in125³30?,the thermal decomposition of lost four molecules of crystal water,during330⁶00?,the thermal decomposition of lost 4 molecule of carbon dioxide and 1water molecules,the end products of magnesium oxide.In line with the industrial production index of basic magnesium carbonate:water content?3%,burning weight loss between 54⁵8%and magnesium oxide content?38%.2.Preparation of basic magnesium carbonate by carbon dioxide captureIn this chapter,basic magnesium carbonate is prepared by the method of carbon dioxide capture.nesquehonite was prepared by using magnesium hydroxide as slurry and carbon dioxide as carbon source.The kinetics of the dissolution of magnesium hydroxide and the formation of nesquehonite was studied by thermogravimetric analysis.Research nesquehonite in different temperature on the influence of the pyrolysis products,and to explore under 60?,adding different amount of NaOH solution preparation of tubular basic magnesium carbonate.The experimental results show that the magnesium hydroxide slurry can successfully capture carbon dioxide and generate bar nesquehonite with a diameter of 1³?m and a length of 5²0?m.To stick nesquehonite as a template,under 60?,add 8 mL of 5 mol/L sodium hydroxide solution,successfully made a tubular basic magnesium carbonate,surface plate shaped structure.Figure 35 table 6 reference 111...