茂名高岭土矿的矿物组成、造纸工艺性能及成矿地质条件探讨

A TENTATIVE DISCUSSION ON THE MAOMING KAOLIN DEPOSIT: MINERAL COMPOSITION, PAPERMAKING TECHNOLOGICAL PROPERTIES AND ORE-FORMING GEOLOGICAL CONDITIONS

茂名高岭土产于上第三系中新统黄牛岭组和上新统老虎岭组。高岭土受地层层位控制,分布广,储量大,埋藏浅,易开采,经济效益明显。矿物组成主要为高岭石和石英,下部矿体含少量伊利石。高岭石为片状晶体,有序度高,粒度细,粒级分布理想,具良好的造纸工艺性能,是我国优质的造纸刮刀涂料级原料。矿床的形成经历了前期的沉积阶段和后期的风化阶段,盆地中的煤层和油页岩氧化形成的酸性环境对风化成矿起了决定性作用。

The Maoming kaolin deposit in Guangdong province, composed of a sort of sedimentry-weathering type sandy kaolin, is a source area of high-quality coating material for papermaking. The kaolin is characterized by extensive distribution, considerable reserevs, small buried depth and easy exploitation, and therefore possesses remarkable economic benefits. The Maoming kaolin deposit is strictly controlled by stratigraphic horizon and lithologic characters, and occurs mainly in Miocene Huangniuling Formation and Pliocene Laohuling Formation. The minerogenegis shows polycyclic characters. The kaolin consists of kaolinite and quartz, with a little illite in the lovwerpart of the orebody and negligible amounts of other minerals. The original ore contains 50-80% quartz and 20-40% kaolinite on average; in<180 mesh ore samples kaolinite increases to 60-67%, and quartz is reduced to some 27%; in<320 samples quartz content decreases to 7-8%, and in samples of<2 micron quartz content can fall to less than 1%. The average-SiO_2 and Al_2O_3 contents are respectively 83.95% and 10.28% in the original ore; however, Al_2O_3 can reach 27.2% in<180 mash ore samples, 30% in<320 mesh samples and 38% in<2 micron coating kaolin. Mineralogical studies show that kaolinite has relatively high degree of order and assumes pseudohexagonal flaky crystals with grains of aggregate usually less than 2 micron. Its ideal granulity and whiteness demonstrate that kaolin possesses quite satisfactory papermaking technological properties. Studies show that the ore-forming process of the ore deposit experienced early sedimeutary stage and late reweathering stage. The acid environment resulting from the oxidation of coal-seam and oil shale played a decisive role in the reweathering, and led to the complete transformation of kaolin and illite into kaolinite.