摘要
近几年发现的产于我国南方第三、第四纪地层中的砂性高岭土矿床规模大,质量优良,矿床在成矿特征,物质组成,粒度组成及工业应用上独具特色,是一种新的高岭土矿床类型即沉积-风化型高岭土矿床。成矿过程经历了前期的沉积作用和后期的风化作用。该类矿床在造纸工业应用上具明显优势,经济价值甚大。
Arenaceous kaolin deposits occurring in Terti aryand Quaternary sediments along the coastal area of South China discovered in recent years, are great in size, shallow in buried depth and fine in ore quality. They are of a new type and might be called sedimentary-weathering type kaolin deposits. Mineral deposits of this type show distinct characteristics in such aspects as minerogenic geological conditions, mineral composition, mineralogy, grain size distribution and industrial uses. They were formed through the further weathering of weathered or semi-weathered materials of granite and acid volcanic rocks similar to granite in composition which had already been transported for a short distance by river into the acid sedimentary basin. During the late-stage weathering process, the weathered materials were further converted into kaolinite as a result of the action of acid media in the basin.
Kaolin deposits are quite simple in mineral composition and consist mainly of kaolinite and quartz. Dressed kaolin contains as high as over 92 percent of kaolinite which is well crystallized and mostly assumes flaky microcrystals (<1μm). In contrast to this type, kaolinite in sedimentary type kaolin deposits is commonly converted into b-axis disordered one as a result of transportation. Chemical analysis shows that in kaolin, Fe_2O_3<1%, TiO_2< 0.5%, and in elaborately dressed kaolin, Fe_2O_3<0.5%, TiO_2<0.3%, and Al_2O_3 and SiO_2 are as high as 38% and 45% respectively, which cause the kaolin to have relatively high natural whiteness. Grain size distribution indicates that its average grain sizes are in the range of 2—6μm with the proportion of <3μm reaching some 50 percent. With these characteristics, the kaolin demonstrates good quality in paper coating industry. Its viscosity is as high as 67—72% (0.5Pas) and its brightness >87%. Experiments show that this type of kaolin is an ideal material for paper coating.
出处
《矿床地质》
CAS
CSCD
北大核心
1991年第3期272-282,共11页
Mineral Deposits
