华南某花岗岩型铀矿床矿石地质特征对铀浸出动力学的影响

The Influence of Geologic Feature of Ores on Kinetics of Uranium Leaching from Some Granite Uranium Deposit in South China

华南花岗岩型铀矿床是我国重要的铀资源之一,主要采用堆浸法提取铀.本文实验研究了铀矿石的地质地球化学特征对铀浸出的影响.根据地质地球化学特征,铀矿石可以分为2个类型,Ⅰ类是发育赤铁矿化,呈暗红色,Fe2O3含量较高,Ca、Ma、Al含量较低;Ⅱ类是发育绢云母化和碳酸盐化,呈灰绿色,Fe2O3含量较低,Ca、Ma、Al含量较高.铀浸出动力学受表面化学反应控制,矿石的地质地球化学特征对铀的浸出有显著影响,Ⅰ类矿石铀的浸出率、铀浓度和浸出速率常数显著高于Ⅱ类矿石.矿石中的赤铁矿为铀浸出提供氧化剂Fe3+,从而促进铀的浸出;碳酸盐矿物一方面消耗酸,另一方面形成沉淀物,从而对铀浸出产生不利影响.

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. Accrrding 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 ki-netics 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.