CO_(2)+O_(2)浸铀过程中矿物溶解量与沉淀量的逆向平衡模拟

Simulation of Inverse Equilibrium of Mineral Dissolution and Precipitation Amounts During Uranium Leaching with CO_(2)+O_(2)

CO_(2)+O_(2)地浸过程中浸出剂与含矿层矿物相互作用后再将铀从矿石中浸出的同时,由于地下水矿化度不断增高又会产生化学沉淀,导致含矿层堵塞。本文以纳岭沟铀矿现场动态地浸(现场浸出)试验与室内静态浸出试验(常温常压)数据为基础,在确定典型浸出剂渗流路径与参与水文地球化学反应的矿物相及反应方向基础上,采用PHREEQC软件对CO_(2)+O_(2)浸铀过程中矿物溶解量与沉淀量进行逆向平衡模拟。模拟结果表明,铀浸出过程中,钾长石、钠长石和钙长石发生了溶解,其在室内静态浸出试验条件下,60~170 d的溶解量分别为0.2~0.26、2.91~3.26、4.58~5.39 mmol/L;在现场浸出条件下的溶解量分别为0.14~1.42、0.27~1.68、0.23~0.75 mmol/L。浸出过程中,伊利石、方解石和三水铝石形成了沉淀,室内浸出条件下,60~170 d的沉淀量分别为5.36~5.9、9.77~11.7、0.40~0.53 mmol/L;现场浸出条件下,其沉淀量分别为0.35~2.79、0.05~1.34、0.39~2.84 mmol/L。以上结果表明,CO_(2)+O_(2)浸铀过程中含矿层的堵塞矿物主要是伊利石、方解石和三水铝石,长石发生黏土化蚀变和方解石沉淀是造成含矿层堵塞的重要机制。

CO_(2)+O_(2) uranium leaching process is the third generation of uranium mining and smelting technology in China,in the leaching process of uranium from the ore after the interaction between the leaching agent and the minerals of the ore-bearing layer,the uranium leaches from the ore at the same time,due to the increasing salinity of groundwater,chemical precipitation will generate,resulting in the blockage of the ore-bearing layer.However,in the past,the hydrogeochemical simulation of ore-bearing layer plugging explored the dissolution and precipitation characteristics of minerals through forward simulation,and qualitatively studied the characteristics of ore-bearing layer blockage.In this paper,based on indoor static leaching test(normal temperature and pressure)and the field dynamic leaching test data of the Nalinggou uranium mine with CO_(2)+O_(2) process,PHREEQC software was used to simulate the mineral dissolution and precipitation,the dissolution and precipitation characteristics of ore-bearing minerals were discussed,and the hydrogeochemical mechanism of the ore-bearing layer blockage of Nalinggou uranium mine was explored.The simulation results show that during the leaching process,potassium feldspar,albite and anorthite dissolve during uranium leaching,under indoor leaching conditions,their dissolution amounts for 60-170 d are 0.2-0.26,2.91-3.26,and 4.58-5.39 mmol/L,respectively.The dissolution amounts under field leaching conditions are 0.14-1.42,0.27-1.68,and 0.23-0.75 mmol/L,respectively.Illite,calcite,and gibbsite form precipitates,under indoor leaching conditions,the precipitation amounts for 60-170 d are 5.36-5.9,9.77-11.7,and 0.40-0.53 mmol/L,respectively.Under field leaching conditions,the precipitation amounts are 0.35-2.79,0.05-1.34,and 0.39-2.84 mmol/L,respectively,and part of CO2(g)is overflowed.Compared with the indoor leaching test,the dissolution amounts of albite,potassium feldspar and calcite in the rock ore in the field leaching test are relatively lower than that of illite and calcite.The above results indicate that the blocking minerals in the ore-bearing layer in the process of CO_(2)+O_(2) uranium leaching are mainly illite,calcite and gibbsite.The formation of illite is the result of clayification and alteration of feldspar minerals,calcite and gibbsite are mainly affected by the concentration of Ca2+,Al3+and pH of the leaching agent,and the higher concentration of Ca2+and Al3+and the increase of pH will lead to the precipitation of calcite and gibbsite.Clayification alteration and calcite precipitation of feldspar are important mechanisms for the ore-bearing layer blockage.