采用工艺优化和动力学模型提高铀矿生物柱浸的回收率

摘要

This research aimed to enhance the column bioleaching recovery of uranium ore byAcidithiobacillus ferrooxidans. Seven factors were examined for their significance on bioleaching using a Plackett-Burman factorial design. Four significant variables ([Fe2+]initial, pH, aeration rate and inoculation percent) were selected for the optimization studies. The effect of these variables on uranium bioleaching was studied using a central composite design (CCD). The optimal values of the variables for the maximum uranium bioleaching recovery (90.27±0.98)% were as follows: [Fe2+]initial=2.89 g/L, aeration rate 420 mL/min, pH 1.45 and inoculation 6% (v/v). [Fe2+]initial was found to be the most effective parameter. The maximum uranium recovery from the predicted models was 92.01%. This value was in agreement with the actual experimental value. The analysis of bioleaching residue of uranium ore under optimum conditions confirmed the formation of K-jarosite on the surface of minerals. By using optimal conditions, uranium bioleaching recovery is increased at column and jarosite precipitation is minimized. The kinetic model showed that uranium recovery has a direct relation with ferric ion concentration.%采用嗜酸氧化亚铁硫杆菌提高轴矿的生物柱浸回收率,利用Plackett-Burman因子设计法研究七因素对铀矿生物柱浸显著性的影响.选取[Fe2+]intial、pH值、通气速率和接种率4个显著性参数进行优化试验,采用一种中心复合设计法研究这些参数对铀矿生物浸出的影响.铀矿生物浸出率最大时((90.27±0.98)%)对应的优化参数如下:[Fe2+]intial=2.89 g/L、通气速率420 mL/min、pH 1.45、接种率6%(体积分数).[Fe2+]intial对铀矿生物浸出的影响最大.由预测模型得到铀的最大回收率为92.01%,此数据与实验所得结果吻合较好.最佳浸出条件下铀矿浸出渣的分析结果表明,矿物表面形成了黄钾铁矾.最佳浸出条件下铀的生物柱浸率提高,黄钾铁矾沉淀量减少.动力学模型预测结果表明,铀的回收率与Fe2+浓度密切相关.