鄂尔多斯盆地大营铀矿铀的赋存状态研究

鄂尔多斯盆地大营铀矿是近几年新发现的砂岩型铀矿,详细研究该矿床铀矿物的赋存状态,对其矿床成因认识及之后的选冶开采均具有重要的意义。笔者利用电子探针和逐级化学提取分析以及α径迹分析等方法,研究了大营铀矿铀的赋存状态。结果发现,铀一部分以铀矿物为主,主要是铀石,另外存在少量的水硅铀石和钛铀矿。在电子探针镜下观察,表明铀矿物呈微粒集合体形式存在于黄铁矿、方解石及有机质裂缝中。逐级化学提取分析发现,各形态铀的含量不均一,其中有机质黄铁矿态占40.88%;其次为碳酸盐态,占28.33%;另外残渣态占24.89%,少部分为离子吸附态和铁锰氧化态,分别占3.2%和2.64%。反映其中铀矿物形式的铀占53.22%,分散吸附态的铀占46.72%。分散吸附态的铀以有机质及黄铁矿吸附占主导。综上所述,大营铀矿铀的赋存状态主要为铀矿物和吸附两种形式,二者所占比例大体相当,以铀矿物存在的铀主要为铀石,以吸附形式存在的铀主要赋存在黄铁矿和有机质中。

Study on Uranium Occurrence State of Daying Sandstone-Type Uranium Deposits in Ordos Basin

The Daying uranium deposit is a newly discovered deposit in Ordos basin recently, the detailed research on the uranium occurrence state has a great significance for mineral smelting and mining. Through using electron probe, sequential chemical extraction and α-trackmethods, the uranium occurrence state of Daying sandstone-type uranium deposits in Ordos Basin has been studied. The results show that the uranium ore is rich in coffinite, containing very small amounts of water silicon coffinite and titanium uranium. These uranium mineral occur as adsemblages, mainly exist in pyrite, calcite and the cracks of organic mattert.The sequential chemical extractionfurther confirms that the percentages of uranium ore in the Daying deposit area significantly different.The average amounts of sulfide-organic matter speciation, carbonates speciation, residual speciation, exchangeable speciation, and Fe-Mn speciation decreased in order as 40.88%, 28.33%, 24.89%, 3.2% and 2.64%.The uranium minerals take up 53.22% of total uranium, while the scattered adsorption uranium occupies 46.72%. And the scattered adsorption uranium is dominated by organic matter and pyrite. To sum up, the Daying uranium deposit mainly occurs as uranium minerals and scattered adsorption uranium, and both of them have same proportion. The uranium minerals are composed of coffinite, while the scattered adsorption uranium is developed within pyrite and organic matter.