Economic Geologic And Metallogenicand Mineralogic Characteristics Of The Chongyi Kaolin Deposit From Jiangxi Province

Kaolin has many physic-chemical features and technical properties,and it is regarded as a unique and important nonmetallic mine.We choose a kaolin deposit at Chongyi,Jiangxi as research object,try to carry out a systematic study of the mineralogical and technological characteristics of kaolin samples,and provide feasible suggestions to improve the quality of the raw ore.The results suggest that(1)The study area is located in the subtropical climate zone,and the parent rock of the kaolin deposit is albitization muscovite-granite,which experienced intense weathering process.Large amounts of Na,Ca and moderate K are leaching from the granite rock,indicating the study kaolin deposit was the product of an alumina-silica period in middle-late weathering.Besides,the fine fraction kaolin samples are rich in trace elements,showing that the trace elements appear concentrated in the fine fractions of the kaolin samples.(2)The main constituent minerals in the samples were identified to be quartz(60 wt.%),kaolinite(15 wt.%),muscovite,gibbisite,and feldspar,etc.The kaolinite is derived from muscovite and/or feldspar,and the size distribution varies from 50?80 ?mto less than 1?m,indicating a supergene alteration for the deposit formation.(3)Iron is mainly concentrated in the oxides(dominated by magnetite)and aluminosilicates(dominated bytourmaline),partly present as "rust" or "film" exist on the surface or among the particles of kaolinite and muscovite,and minor exist in the lattice ofiron-bearing minerals(e.g.,biotite,pyroxene,and hornblende),kaolinite and muscovite.(4)Most of the quartz are removed from the simple "wash-screen-magnetic separation process",which caused inmarkedly increase of the kaolinite amount(30-55 wt.%).The average size of the kaolinite particles isranging from 10-30 ?m,and they have medium fired whiteness(38?73)and plasticity(28?37).The quality of the kaolin is largely influenced by mica and iron,and we can use some methods to lower the impacts.The grain size of the raw kaolin particles and the iron content are sharply decreased(-10 ?m or-2 ?m and<0.3 wt.%,respectively),and the whiteness is increased by using some technologies,such as purification,grinding,magneto-gravitational separation and medicament.Besides,the value-added product and market competitiveness will also be improved.