The effect of ultraviolet mutagenesis on a heterotrophic strain(Providencia JAT-1) mutation was studied and bioleaching of low grade copper ore with mutant bacteria was investigated. The results show that the activity of bacteria was improved after ultraviolet mutagenesis; the best irradiation time was 120 s. Compared to the original bacteria, the cells density of mutant bacteria at stationary phase increased by 26% and ammonia produced by mutant bacteria increased by 12%. Higher activity of bacteria leads to a higher copper extraction rate. The bioleaching performance of Providencia JAT-1 was improved after UV mutagenesis. The copper extraction rate with mutant bacteria increased by 10.6% compared to the original bacteria. The ore surface was corroded and the fine particles were absent after bioleaching. Free copper oxide and copper silicates could be leached out easily by using JAT-1; a small part of the copper sulfide can also be leached out. Bioleaching using JAT-1 is more effective than ammonia leaching and copper extraction rate with mutant bacteria was 21.1% higher than that by ammonia leaching under the same condition.
锦丰金矿露天边坡岩体复杂破碎,东南西北4个方位的边坡均出现了不同程度的滑坡等破坏情况。为保证安全高效生产,实现陡帮开采,对开采过程中露天边坡的稳定性进行了数值模拟研究,分别在数值模型的坑底、东部边坡与西部边坡各设置3个点位,通过对比其三维空间上的位移情况,发现西部边坡受采动影响较大。建议着重加强对西部边坡的加固与支护,并采用重力挡土墙对其进行护坡;对挡土墙的墙体及抗滑桩相关参数进行了计算,设计并选定在西部边坡660~640 m水平段较为破碎的边坡处建设了挡土墙。结果表明：水平方向上,在保证墙体上部线载荷不低于782 k N/m、底部线载荷不低于160 k N/m且抗滑桩抗剪线载荷不低于471 k N/m的情况下施工挡土墙,其抗倾覆稳定系数与抗滑动稳定系数均大于挡土墙建设的安全标准,能够满足陡帮开采护坡的设计要求。
To solve the problem of slow leaching speed of copper,surfactant was added into lixivium as leaching agent in the experiment.Based on physical chemistry and seepage flow mechanics,the leaching mechanics of surfactant was analyzed.The solution surface tension and surfactant adsorbing on the surface of ore have a significant impact on the surface wetting effect.With leaching rate for response,the study screened out three main factors by Plackett-Burman design method:the sulfuric acid concentration,surfactant concentration and temperature.Among these three factors,the surfactant concentration is the most important contributor to leaching rate.After obtaining the experiment center by the steepest ascent experiment,a continuous variable surface model was built by response surface methodology.By solving quadratic polynomial equation,optimal conditions for leaching were finally obtained as follows:the sulfuric acid concentration was 60 g/L,the surfactant concentration was 0.00914 mol/L,and the temperature was 45 °C.The leaching rate was 66.81% in the optimized leaching conditions,which was close to the predicted value,showing that regression result was good.
