某含磷铀矿石难浸原因探讨

Investigation on the leaching behaviors of a kind of phosphor-bearing uranium ore

某铀矿床为中低温热液铀矿床,主要矿物有石英、长石、绿泥石、方解石、磷灰石等。铀矿物以沥青铀矿为主。由于绿泥石、方解石、磷灰石等高耗酸组分的存在,酸法浸出时,硫酸消耗与矿石质量比高达30%,而且需要2.5%的氧化剂MnO2,生产成本高。加压碱浸,温度135℃,0.8 MPa,铀浸出率仅74.2%。由于矿石中总铀质量的41.8%存在于磷灰石中,其中至少39%的铀与磷灰石紧密共生,或者以类质同象存在于磷灰石晶格中,而碳酸盐又不能与磷灰石发生作用,所以碱浸时铀浸出率低。

This kind of uranium ore consists of quartz, feldspar, chlorite, calcite, phosphorite etc.Uranium minerals include mainly pitchblende. In the process of acid leaching, the consumption of sulphuric acid is high to 30% due to those acid-consuming minerals. Moreover, 2.5% MnO2 is required as its oxidant. Hence, it is economically unacceptable to recovery uranium from the uranium ores by acid leaching. In the conditions of 135 ℃ and 0. 8 MPa, the leaching rate of uranium reaches up 74.2% in alkaline process. Experiments were conducted to probe into the leaching behavior of the uranium ores in alkaline process. It is indicated that 41.8% uranium occurs in phosphorite, of which more than 39% is the intergrowth of phosphorite, and/or its isomorphism. Carbonate could not decompose these intergrowths and isomorphism encapsulated by phosphorite, hence leads to low uranium recovery.