高硫含砷难处理金精矿生物预氧化及微生物种群研究

Bio-Pretreatment and Community Analysis for High Sulfur Arsenic-Bearing Refractory Gold Concentrate

贵州某金矿石金品位低且嵌布粒度极细(多数小于2μm,且多为硫化物包裹),浮选金精矿硫含量高且含砷,是一种典型的难处理金矿。本文利用混合菌NB对浮选金精矿进行生物预氧化,考察了NB菌的最适生长pH,最佳生长温度。在有菌体系下,采用直接氧化,恒定pH氧化以及分两段氧化3种方法对其预处理,得出以下结论:直接氧化可以得到较好的氧化效果,恒定pH氧化可减少酸积累对微生物活性的影响,提高硫氧化速率,但是与此同时会在矿物表面产生黄钾铁矾沉淀形成二次包裹,分段氧化既可以较少酸积累带来的负面影响,又可以避免矿物表面形成黄钾铁矾。在15%矿浆浓度以及初始pH为1.5的条件下,一段氧化7 d,二段氧化7 d,硫、砷氧化率分别达到89.31%和79.56%。利用荧光定量PCR查明了该混合菌的组成为:Sulfobacillus thermotolerans,Leptospirillum ferriphilum和古菌Ferroplasma acidiphilum,其中古菌Ferroplasma acidiphilum占到98.36%,该古菌在预氧化过程中起到了决定性作用。

A gold mine of Guizhou had a low grade and the gold particle size was extremely small（ mostly less than 2 μm）. Flotation concentrates contained arsenic and had a high grade of sulphur. It was a typical refractory metallurgical gold ore. Mixed bacteria NB was used for oxidation pretreatment, and optimum growth pH and temperature were studied. As a system with mixed bacteria, three methods were considered for oxidation pretreatment： direct oxidation, constant pH and two-stage oxidation. It was found that the direct oxidation could get good effect of oxidation, constant pH could improve the sulfur oxidation rate and reduce the acid accumulation effects on microbial activity, but in this case, jarosite precipitation was produced on the mineral surface and formed the second parcel. A two-stage oxidation not only could reduce acid accumulation of negative influence but also could avoid mineral surface sediment. Un- der the condition 15% of pulp concentration and initial pH of 1.5, stair oxidation for 7 d then secondary oxidation for 7 d, the sulfur and arsenic oxidation rate reached 89.31% and 79.56% , respectively. The results of fluorescence quantify-polymerase chain reaction （FQ-PCR） showed that the oxidation system included Sulfobacillus thermotolerans, Leptospirillumferriphilum and Ferroplasma acidiphi- lure. Among them Ferroplasma acidiphilum accounting for 98.36%, the archaea in the pre-oxidation process played a decisive role.