高碳酸盐型铀矿床微酸中性地浸采铀试验

某砂岩铀矿碳酸盐含量高,为避免常规酸法或碱法地浸的化学堵塞,开展了微酸中性地浸试验。以0.3g/L的硫酸溶液为溶浸剂,双氧水、氧气为氧化剂。浸出体系pH控制在6.1~6.7避免了碳酸钙沉淀;Ca~(2+)、SO_4~(2-)分别不超过900mg/L和2 100mg/L,硫酸钙沉淀得到有效控制。酸液与矿石碳酸盐反应可获得400~450mg/L的HCO_3~-作为浸铀剂,在双氧水氧化条件下可使浸出铀浓度达到24~31mg/L,改用300~350mg/L的氧气则使铀浓度进一步升高到48~62mg/L。与常规酸法和碱法工艺相比,微酸中性工艺更有利于在浸铀的同时对硫酸钙和碳酸钙沉淀进行有效控制。

Low Acid Neutral In-situ Leaching of Uranium Mining with High Content of Carbonates Uranium Deposit

High content of carbonates is prone to cause chemical blockage during acid or alkaline in situ leaching for uranium mine at a sandstone-type deposit. The field pilot experiment of low acid neutral in situ leaching was conducted with 0.3 g/L of sulfuric acid solution as leaching agent, and hydrogen peroxide and oxygen as oxidants. PH value of leaching system is controlled at level of 6.1~6.7 to avoid calcium carbonate precipitation. Content of Ca2 and SO42- does not exceed 900 mg/L and 2100 mg/L respectively to control calcium sulfate precipitation. Reaction between acid and carbonates produces 400~450 mg/L of HCO3-, which can be used as complexant of uranyl. Recovery uranium concentration is 24~31 mg/L with oxidation of hydrogen peroxide, and it rises to 48~62 mg/L by 300~350 mg/L of oxygen. Compared with conventional acid or alkaline leaching process, low acid neutral leaching technology facilitates uranium leaching and avoids precipitation of both calcium sulfate and calcium carbonate.