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(一)沉积磷块岩的矿石性质 我国大型沉积磷块岩矿床多数成矿于震旦纪—寒武纪的元古代和早古生代,磷矿物与脉石矿物紧密胶结共生,矿石坚硬。磷矿层赋存于白云岩和页岩的岩系中,多为倾斜或缓倾斜中厚矿体,层数多和规模大。 各主要矿区的矿石结构构造基本相似,磷矿物的结晶形态为隐晶质、微晶质和胶状均质体,呈鲕状、假鲕状结构。由胶磷矿鲕粒可构成致密块状,条带状、层状或微层状构造。在胶磷矿的鲕粒中或鲕粒间,混入数量不等的极细的碳酸盐和硅酸盐脉石矿物。由胶磷矿鲕粒密集构成的致密状磷块岩和含磷条带,其中P_2O_5含量高,杂质含量少,两条带状磷块岩品位高低则取决于含磷条带与脉石条带的厚度和比例。所以,磷块岩矿石
(I) Ore Characteristics of Sedimentary Phosphorite Most of the large-scale sedimentary phosphorous rock deposits in China were mineralized during the Sinian to Cambrian Proterozoic and Early Paleozoic. Phosphorus minerals and gangue minerals were closely cemented together and their ores were hard. Phosphorite layer occurs in the dolomite and shale rock series, mostly inclined or gently inclined thick ore body, the number of layers and large scale. The ore structures of the main mining areas are basically similar in structure. The crystalline forms of the phosphate minerals are cryptocrystalline, microcrystalline and colloidal homogenous bodies with oolitic and pseudo-oolitic structures. The colloidal dolomite ooids can form a dense block, strip, layer or micro-layered structure. In the colloidal ooids or ooids, mixed with varying amounts of very fine carbonate and silicate gangue minerals. Dense phosphogypsum and phosphorus-bearing strata composed of oolitic grains of colloidal phosphate, of which the content of P_2O_5 is high and the content of impurities is small. The grade of two strata of phosphatic rock depends on the phosphorus-bearing and gangue strata Thickness and ratio. So, phosphorite ore