Study On Whitening Technology And Comprehensive Utilization Of Kaolin

Kaolin in Inner Mongolia is rich in mineral resources.Although its natural whiteness is high,its calcined whiteness is low,which is an important factor limiting the application of kaolin with high added value.In this thesis,wet and dry processes were used to remove impurity and whiten kaolin in Inner Mongolia,and the whiteness of calcined samples was more than 85%,which greatly increased its application value.The impurity-removing and whitening of kaolin from different mineral sites(1#,2#,3#,6#,7#)were studied using mechanical activation and acetic acid leaching methods respectively.The whiteness of calcined kaolin from some mineral sites(1#,2#,7#)reached over 85%after treated by both methods.After the two processes are amplified,the average whiteness of calcined kaolin is 86.3%and 86.8%for mechanical activation and acetic acid leaching methods respectively,all of which are more than 85%,which provides basic data for the later pilot experiment.In view of the whiteness of calcined kaolin from some sites cannot reach 85%,the new whitening process of kaolin is further explored.It was found that the calcination whiteness of 1#,2#,3#,4#and 7#kaolin treated by wet mechanical activation method has reached more than 85%.Because the above three processes cannot make the calcination whiteness of 6#kaolin reach 85%,oxalic acid leaching method was used to treated the sample,and the calcination whiteness of 6#kaolin can reach 86.4%after treatment.The surface of low-grade sandy kaolin(5#kaolin)was infected with a lot of hematite,and oxalic acid leaching was the most effective method to treat this kind of kaolin.Therefore,oxalic acid leaching was used to remove iron and whiten 5#Kaolin.The effects of sodium chloride addition and calcination temperature on the ceramization of 5#kaolin were studied.In addition,in order to make the best use of5#kaolin,the Na P molecular sieve was synthesized by hydrothermal method,and the specific surface area of the material was increased from 89 m~2/g to 157 m~2/g.Coal kaolin is a by-product of coal mining.With the increase of energy consumption,the production of coal kaolin increased rapidly.The accumulated coal kaolin has not been properly used,resulting in multiple problems such as resource waste,waste treatment and environmental pollution.In this thesis,the coal kaolin was used as a raw material to prepare nanocomposite by RF plasma technology,in order to improve its economic value.After the treatment,the lamellae of coal kaolin became thinner,the particle size became smaller,and the specific surface area increased from 3 m~2/g to 35 m~2/g.