The influence of geologic feature of ores on kinetics of uranium leaching from some granite uranium deposit in south China

The granite uranium deposits in south China are one of important uranium resources, and uranium is mainly extracted using heap leaching. The influence of geological and geochemical characteristics of ores on uranium leaching was experimentally studied in this paper. According to geological and geochemical characteristics, uranium ores can be divided into two types: type Ⅰ is kermesinus with hematization, and high content of Fe₂O₃, low content of Ca, Mg, Al-bearing minerals; type Ⅱ is grayish-green with sericitization, carbonatation, low content of Fe₂O₃, and high content of Ca, Mg, Al-bearing minerals. The kinetics of uranium leaching are controlled by surface chemical reaction. The uranium leaching is affected obviously by geological and geochemical characteristoics of ores. The leaching efficiency, concentration and leaching rate constant of uranium for type Ⅰ ores are higher than for type Ⅱ ores. The dissolution of hematite from ores provide oxidant Fe³⁺ which promote uranium leaching. But carbonate minerals can consume acid and form new precipitates thus be unfavourable to uranium leaching. (authors)