| Gold and silver are considered as valuable and strategic mineral resources, which play key role in the development of China. Because of the socio economic development of human being, particular interest is constantly put in the exploitation and beneficiation of these minerals. As a matter of fact, the processing of gold and silver low grade is systematically carried out, whereas the process of treatment remains difficult and troubling shortage of the resources is obvious. Moreover, people are usually focus on the recovery of gold and silver while ignoring the others valuable minerals. This fact obviously generates a lot of tailings, and not only deteriorates the environment, but also assimilates as a waste of resources. Therefore, an efficient utilization of the mineral resources could have an economic and environmental benefit.In this study, the polymetallic gold-silver ore used was from Guangxi province. The gold and silver content are respectively 5.2g/t and 801g/t, while the other minerals which are considerate to have a high recovery potential are lead, zinc, sulfur, etc. The efficiency of the conventional leaching process used with this ore is very low. However, the pre-treatment step which involve roasting or chemical oxidation, follow by leaching treatment give better results, but the process is concerned by high energy consumption/production and difficulties to achieved comprehensive recovery of zinc and lead.Based on the ore characteristic, flotation-leaching process was implemented to recover the valuable minerals. First, sodium sulfide and butyl xanthate are respectively used as activator and collector during the flotation step in order to generate a crude mixed concentrate of lead and zinc. Afterwards, the experiment used zinc sulfate and sodium sulfite as zinc inhibitor agent, lime to adjust pH and as sulfur inhibitor agent, diethyldithiocarbamate as collector, then reuse zinc inhibitor agent, and sulfur for lead flotation to obtained lead concentrate and crude mixed zinc-sulfur concentrate. Finally, copper sulfate is used as activator, lime to adjust pH and as sulfur inhibitor agent, butyl xanthate as collector, not only for the treatment of crude concentrate of zinc and sulfur, but also inhibit zinc flotation and get concentrate zinc and sulfur mineral. Following flotation experimental test, concentrates of lead, sulfur, sulfur and flotation tailings are obtained. subsequently, chlorination oxidation leaching of the flotation tailings is carried out in order to treat gold and silver. To summarize, flotation-leaching process can be considerate as a route to achieve comprehensive recovery of gold, silver, lead and zinc and other valuable minerals.Flotation test results show that the lead separation from zinc is reached and the beneficiation is highly achieved, and the recovery rate is respectively 88.50% and 85.23% for Pb and Zn. Moreover, the results show that the silver is mainly enriched during the flotation process and embedded in the lead concentrate, with a recovery rate of 67.35%, while a lot of gold floated in surface, and mainly went through the concentrate of sulfur with a recovery rate of 74.68%. The grade of lead and zinc in the tailings get from the flotation process were comparatively low, but it with a small amount of gold and silver the content of gold, so it's considering to recovery gold and silver by a leaching way.Tailings flotation leaching results showed that the optimum leaching conditions were as follows:liquid to solid ratio of about 2ml/g, amount of sodium hypochlorite and hydrochloric acid were 9% and 16%, leaching time 8h. Under these conditions, the leaching rate of silver was 91.52%, for a gold leaching rate of 76.40%. |
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