Overall Presentation of three types of kaolin deposits
Kaolin deposits of China may be divided into three types: weathering type, hydrothermal alteration type and sedimentary type, and each type may be further divided into two subtypes. All types and subtypes have their own characteristics in respect to the temporal-spatial distribution and metallogeny.
(1) Weathering residual subtype kaolin deposits
Kaolin deposits of this subtype are widespread in Jiangxi, Hunan, Guangxi, Guangdong and Fujian of southern China, and also occur in small amounts in Liaoning and Hebei of northern China. The distribution of the deposits coincides with that of extensive Mesozoic (Yanshanian) granites and related dikes in southern China. Deposits are usually preserved on monadnocks in hills, platforms or intermontane basins, where the pre-existing alteration superimposed by subsequent weathering constitutes the most favorable kaolin-forming conditions. The weathering depth is generally 50 m and may be up to more than 100 m. Orebodies occur in bed-like, trough-like, lenticular and irregular shapes. They are 15~35 m thick and relatively persistent. The deposits are commonly medium and small in size, a few are large, and exceptional ones are superlarge. The deposits belonging to this subtype are the Gaoling deposit at Jingdezhen City, Jiangxi, the Jiebei deposit at Hengyang City, Hunan, the Dashujiao deposit at Leping County, Guangxi, the Shandai deposit at Zhanjiang City, Guangdong, and the Xiaxi deposit at Donggong, Longyan City, Fujian.
(2) Weathering leaching subtype kaolin deposits
This subtype of deposit is represented by halloysite (called ‘xuyongite’ by the local people) deposits occurring on the Sichuan-Guizhou border, and also found at Yangdong, Suzhou, Jiangsu. It occurs between karst erosion planes or in karst caves of Permian limestone. Orebodies occur as nests or irregular bodies, which are generally several meters thick and not persistent. Deposits are mostly small in size. To this subtype belong kaolin deposits at Xuyong, Sichuan Province, and Xieshui, Guizhou Province.
(3) Hydrothermal alteration subtype kaolin deposits
Deposits of this subtype are widely distributed in China, mainly along the circum-Pacific Upper Jurassic volcanic rock belt in eastern China and the Jurassic-Cretaceous volcanic rock belt on the northern margin of the North China platform. The presence of faults and penetration of many dikes are favorable ore-forming factors. Dickite as a high-temperature altered mineral sometimes appears in deposits and sometimes becomes dickite clay. In some cases, kaolin is associated with pyrophyllite and alunite and in some cases occurs in the outer alteration zone of the endogenic metallic mineral deposit. Orebodies occur as beds, veins, lenses and irregular bodies, generally a few meters to dozens of meters thick. They are characterized by shallow burial, steep dipping and unstable thickness. The deposits are generally small in size and exceptionally large or superlarge in size. To this subtype belong the Guanshan deposit at Suzhou, Jiangsu, the Yichun deposit in Jiangxi, the Yongjia deposit in Zhejiang, the Anning deposit in Yunnan, the Dehua deposit in Fujian, the Ningcheng deposit in Inner Mongolia and the Anning deposit in Yunnan.
(4) Hot spring alteration subtype kaolin deposits
Deposits of this subtype are mostly related to Quaternary volcanic and geothermal activities and generally distributed along fault zones. Orebodies occur as beds, veins, lenses and irregular bodies, a few to a few dozen meters thick and impersistent. The size of the deposits are usually small. The Tengchong deposit in Yunnan belongs to this subtype.As the professional manufacturer of complete sets of mining machinery, such as cement mill,Mobile crusher, Henan Hongxing is always doing the best in products and service.limestone rotary kiln:http://www.hxjq-crusher.com/23.html.ore separating line:http://www.hxjqchina.com/.
(5) Sedimentary and sedimentary weathering subtype kaolin deposits
Deposits of this subtype are mostly hosted in Tertiary or Quaternary fluvial, lacustrine and bay sediments and kaolin is usually deposited in down-faulted basins, valley depressions or adjacent bays. Kaolin deposits are formed by short-distance transport, deposition and weathering of granite weathering and erosion products around sedimentary basins. Granitic rocks are widespread along the southeast coast of China. The strongly weathered river valleys and bays are favorable areas for kaolin formation. Orebodies occur as beds and lenses, generally 10 m thick, and those of superlarge deposits may be up to dozens of meters to over 100 m thick. The deposits vary greatly in size from small to superlarge ones. Deposits belonging to this subtype are the Maoming deposit in Guangdong, Hepu deposit in Guangxi and Tong’an deposit and Ningde deposit in Fujian.
(6) Kaolin claystone subtype kaolin deposits in coal measures
There are usually several beds of kaolin claystone (hard kaolin) intercalated in Carboni-ferous-Permian coal measures of northern China. Although they are commonly very thin, only a few centimeters to 10 cm thick, kaolin claystone of commercial value has been found in coal measures at Datong, Hunyuan, Huairen, Shanyin and Shuozhou of Shanxi, Baotou, Jungar, Wuda and Wuhai (Haibowan) of Inner Mongolia, Jiaozhu and Gongxian of Henan, Boshan of Shandong, Xuzhou of Jiangsu and Tongchuan of Shaanxi. It is quite widespread and its thickness is generally 30~45 cm in the Yanbei area, Shanxi, and may attain a few meters in the Jungar Qi coalfield, Inner Mongolia, where the total resources are quite large. The deposits that have been explored are only some medium-sized and small deposits, such as the Louzigou deposit in the Pinglu District, Shuozou City, Shanxi, and the Mu’ergou deposit in the Haibowan District, Wuhai City, Inner Mongolia. Their retained reserves are not large. The kaolin claystone beds of this subtype were previously used as markers of correlation between coal beds and strata in coal measures. In recent years kaolin claystone has been mined on a small scale or recovered as a by-product during coal mining, but it is mostly used as ordinary refractories. Recent technological tests show that this subtype of kaolin can be used as a high-duty refractory for melting optical glass pots and can gradually replace shell-type materials such as fused corundum and the main material of synthetic mullite in the fine mould founding technology.
Among the ore types in China’s kaolin occurrences with retained reserves, sandy kaolin is dominant, accounting for about 62% of the total reserves; soft kaolin and hard kaolin contribute 6% and 5% of the total reserves respectively; kaolin reserves of other unclassified types of deposit constitute 27% of the total. The sand content of sandy kaolin is 50%. It generally has good dressing performance and can be used as ordinary ceramic clay after water washing and sand removal by natural deposition; high-duty products can be made after mechanical removal of sand and impurities such as iron, titanium and sulfur. Generally, good dressing results can be obtained, except for a few mines that produce kaolin containing micron-sized alunite.