选冶联合提高甘肃某难浸金矿浮选尾矿金回收率的试验研究

甘肃某金矿矿石金质量分数为4.3×10-6,锑、砷和碳依次为0.48%、0.37%和1.84%,属于典型的复杂难处理锑金矿,现场生产采用"重选-浮选-浮尾氰化"工艺回收金和锑。由于矿石中金嵌布粒度粗细不均,锑、砷和碳等杂质含量高,导致金总回收率仅为82%,金损失严重。为提高金回收率,采用电子探针对浮选尾矿中金的赋存状态进行了研究,在此基础上开展了提高金回收率的试验研究。试验结果表明:浮选尾矿中部分金以晶格金或包裹金形式赋存于毒砂、黄铁矿和辉锑矿等硫化矿物中,氰化浸出过程中难以与浸出液接触,是导致金损失过高的主要原因;氰化浸出前先对浮选尾矿进行分级,分级后对+0.038 mm粗粒级进行再磨和活化浮选,强化对包裹金和晶格金的回收,然后再将粗粒浮选尾矿与-0.038 mm细粒级合并进行氰化浸出,金总回收率可提高约9个百分点,尾渣中金质量分数降低至0.3×10-6以下。

Study on the Gold Recovery from Flotation Tailings of a Refractory Gold Ores in Gansu Province by a Process Combining Mineral Processing and Metallurgy

There are an abundant gold ores resource in China,and most of gold ores are belong to the refractory ores. The gold in the refractory ores is difficult to recovery by the leaching technology because of the fine dissemination particles in ores. Besides,the natural gold ores usually coexisted with pyrite,arsenopyrite and stibnite and is generally enclosed in these sulfide minerals. The conventional cyanide leaching is difficult to process this gold ore.In this paper,a gold ore from Gansu Province of China contains Au 4.3×10-6,Sb 0.48%,As0.37% and C 1.84%,which belongs to a refractory gold. The recovery of gold is very low when the ore was directly leached by the cyanide leaching technology. In order to improve the recovery of gold,the gold was recovered in industrial scale by a process combined the gravity separation,froth flotation and cyanide leaching.However,the recovery rate of gold only is 82% due to the gold with a complex dissemination relationship in ores,the gold grade in the final cyanide leaching residue is approximately 0.8×10-6. In order to increase the recovery rate of gold,the occurrence state of gold in flotation tailings was investigated by electron probe microanalysis(EPMA),the flotation tests were conducted in laboratory scale based on the mineralogy results of the flotation tailings.The results indicated that gold in flotation tailings was mainly existed in the formation of lattice gold in arsenopyrite,pyrite and stibnite the or enclosed in these sulfide minerals with the fine dissemination particles size. When the flotation tailings was leached by cyanide solution,the gold enclosed in these sulfide minerals cannot contact effectively with the cyanide solution even if under the very fine grinding fineness.However,the recovery rate of gold was significantly improved when the flotation tailings were firstly sieved before cyanide leaching. After sieving,the coarse particles with the particles size of +0.038 mm was regrinded and increase the liberation degree of pyrite,arsenopyrite and stibnite. After that,the regrinding products was subject to the froth flotation again in order to recovery these sulfide mineral,the tailings after flotation were subjected to the cyanide leaching together with the-0.038 mm fine particles.The recovery rate of gold is obviously increased by 81.3% to 90.21% by using this process,the grade of gold in the final leaching residue is less than 0.3×10-6. The experimental result is helpful for the improvement of industrial production process.