The Research Of Making Of High-purity Magnesium Oxide Prepared With Haicheng Magnesite

The output of Magnesite,which is one of the important dominating nonmetallic mineral resources in our country,and the export of its corresponding products,are both in the first place in the world.In recent years in our country,the utilization of magnesite resource has been in an embarrassing situation that regardless of the superior quality of its raw materials,the processing is of secondary degree,its products are of single category,and the products are of low added-value.Regrettably,a large amount of the high-quality resource has been used as raw materialsin the production of low value-added products,but only a small amount has been used in the production of high-tech products.It is viewed as a kind of big waste in the former case.As a kind of inorganic chemical product with important industrial value,Magnesium oxide has been widely soused in fields of fuel,medicine,rubber,reagents,livestock feed,architecture,chemical fertilizers,paper making,and even in environmental protection.The high purity magnesium oxide is not only a kind of magnesium chemicals,but also it is of high commercial value.In this paper,in view of the current situation of magnesite industry in China,and from the perspective of economic benefits and sustainable development,the author puts forward that our country should research and develop new high value-added products,and quicken the step of technological innovations on the basis of full utilization of the advantages of magnesite resources.This research aims at the comparison between the respective effects as in Haicheng magnesite oxide of high purity made through steps of roasting,leach in the ammonia salt,and the preparation of magnesium hydroxide by use of ammonia precipitation,and after calcinations,and in the light-burned magnesite oxide made after the steps of leach in ammonium chloride solution and the ammonium chloride solution as well.Besides,the author has also made an investigation of the impact on the effect from the change of the added hydrophilic drugs on the surface of light-burned powder of the magnesia.The focus of the research in the experiment is on the main influencing factors during the preparation,and the optimum conditions for preparation by means of the leach of Haicheng magnesite in ammonia salt been determined: the optimum granularity for the magnesite roasting is-2 mm,the optimum temperature is 800?,and the optimum roasting time is 40 min.In accordance with the comparison of conditions and effects of the leaches of the magnesite in ammonium chloride and in ammonium sulfate,the optimum conditions determined for ammonium sulfate used as the leaching agent for the light-burned magnesium oxide is 4g,the light-burned powder corresponding to 2.5 mol/L(ammonium chloride solution for 150ml)(magnesium oxide with the ammonium chloride reaction mol ratio of 1 : 3.75),the reaction time is 1h,the leaching temperature is 60?,and the best stirring speed is400 r/min.The research in the experiment of the effect on the leaching rate of the light-burned magnesium oxide by means of the change of the hydrophilic shows that the four agents: sodium silicate,sodium hexametaphosphate,sodium carboxymethyl cellulose,and EDETA TETRASODIUM have different degrees of effects on the leaching process.In the experiment of the preparation of the magnesium hydroxide in Ammonia as the precipitant and in the leaching agent of the light-burned magnesium oxide,the precipitation time for reacting with leaching agent of the light-burned magnesium oxide is 60 min in 8 mol/L,the concentration of ammonia,the reaction temperature is 45?,and the best stirring speed is 500 r/min.The optimal roasting temperature for magnesium hydroxide is 500?,the best roasting time being 30 min.The contents in the MgO made under the above conditions is 99.85%.