松辽盆地北部砂岩型铀矿铀的赋存状态研究

Research on uranium occurrence state of sandstone-type uranium deposit in the northern Songliao Basin

松辽盆地北部是近年来发现的砂岩型铀矿找矿潜力较大的地区。采用电子探针及化学分析等方法,对该地区砂岩型铀矿中铀矿物的赋存状态及铀的价态进行研究。发现松辽盆地北部砂岩型铀矿铀的赋存状态以独立铀矿为主,主要为沥青铀矿和铀石;铀矿物颗粒细小,多以粒状、斑点状、团块状、条带状、网状、环带状及分散显微颗粒、显微颗粒集合体的形式存在,颗粒大小几微米至200μm;铀矿石主要与黄铁矿、石英、长石共生,分布在碎屑颗粒间或裂隙中,或充填于砂岩胶结物中,或围绕黄铁矿生长形成镶边状。从铀矿物的赋存状态及类型看,松辽盆地北部铀矿化可能存在两个成矿期,即同生沉积期和后生改造叠加期。矿石中U^(6+)/U^(4+)比值为0.30~2.07,平均为0.93,铀含量较高的矿石U^(6+)/U^(4+)比值高于铀含量较低的矿石,普遍大于1,有利于铀矿地浸开采。上述研究为松辽盆地北部砂岩型铀矿找矿、成矿机理研究提供了基础资料,同时对砂岩型铀矿选冶开采工艺的确定具有借鉴意义。

The northern Songliao Basin is a greater prospecting potential area for sandstone-type uranium deposits which are found out in recent years.The occurrence status of uranium minerals and the valence state of uranium in sandstone-type uranium deposits in this area are studied by means of electron probe and chemical analysis.It is found that the occurrence state of uranium element of these uranium deposits in the northern Songliao Basin is dominated by independent uranium minerals,mainly in asphalt uranium ore and uranium ore.Uranium mineral particles are small,mostly in the form of granular,spotted,agglomerated,striped,reticular,looped shape and dispersed microparticles,microparticle aggregates and the size of grains is about nμm-200μm.Uranium minerals are mainly associated with pyrite,quartz,feldspar which are distributed between the debris particles or in the cracks,or filled in the sandstone cement,or to form a trim around the formation of pyrite.From the occurrence state and types of uranium minerals,uranium mineralization in northern Songliao Basin might have two phases,the syngenic sedimentary period and superposition period of the epigenetic transformation.The ratio of U6+/U 4+in ore is 0.30-2.07,the average value is 0.93.The ratio of U6+/U 4+of ore with great uranium content is higher than that of ore with low uranium content,which is generally greater than 1 and is favorable for uranium in-situ leaching mining and development.The above research provides the basic data for the exploration and metallogenic mechanism of sandstone-type uranium deposits in the northern Songliao Basin.It is also useful for the determination of processing and mining technology of sandstone-type uranium deposits as well.