Biosorption of gold from alkaline solution using biomass wastes.

黄金是最昂贵的贵金属之一，不仅被广泛用作传统珠宝，而且还被广泛用作各种众所周知的先进材料的有用成分，如电气和电子设备，催化剂和医疗器械。一方面，黄金的供应非常有限;另一方面，这种有价值的金属的很大一部分通常在金属精炼以及废弃电子设备的处理过程中以含水副产品的形式被丢弃。因此，迫切需要开发与从一次和二次资源中提取/回收黄金有关的有效和经济的回收工艺。最近，基于低成本和广泛可用的生物质材料的吸附过程被认为是可用于从稀溶液中回收金的最有前途的可持续技术之一。在过去的3年里，我们在生物吸附研究方面取得了重大进展，在国际知名期刊上发表了30多篇论文，如Bioresource Technology，Chemical Engineering Journal，Industrial & Engineering Chemistry Research，绿色化学，Journal of Chemical & Engineering Data，Journal of Hazardous Materials，Hydrometallurgy，Solvent Extraction and Ion Exchange，RSC Advances，我们还在TMS、CIM/MetSoc、IEX、阿尔塔等世界级会议上发表了10多篇与该研究相关的会议论文。随着生物吸附研究在过去3年中取得的巨大进展，我们现在已经做好了充分的准备，继续扩大我们在湿法冶金领域的研究。 拟议的研究计划的目标是为开发具有成本效益的，可持续的和有效的回收工艺奠定科学基础，用于使用从生物质废物制备的生物材料从稀溶液中提取金。目前最常用的从金矿石中浸金的技术仍然是在碱性氰化物水溶液中浸金。最近，巴里克黄金公司在其成功的示范工厂操作中采用了碱性硫代硫酸盐处理黄金，虽然硫代硫酸盐不能完全取代氰化物，但它可以提供氰化物的替代品。继我们通过先前的发现资助成功地从酸性溶液中回收黄金的研究工作之后，在我们拟议的研究中，我们计划将我们的工作扩展到从氰化物和硫代硫酸盐的碱性溶液中回收黄金，以满足行业的迫切需求。在这项研究中，将回收金从稀碱性溶液在间歇反应器中使用化学改性的纤维素生物材料。最初市售的纯纤维素，经过硫酸预处理，然后接枝独特的官能团，将用于开发动力学和吸附等温线模型。随后将从纤维素生物质废物如废纸、废棉和废木材/锯木屑制备生物吸附剂，将测试其从真实的溶液中的金吸附。这些生物质废物是大量可用的，将是制造生物吸附剂的廉价原材料来源。适当使用这种生物质废物作为增值产品不仅会减少每天产生的废物量，而且对金矿开采业也具有高端价值，因为这种廉价的生物吸附剂将具有比传统使用的活性炭更优越的上级性能。采矿和废物管理公司都将从这项研究中受益。拟议的研究计划将培养4名硕士，1名博士，5名博士后和4名本科生在提取冶金领域。

Gold is one of the most expensive precious metals that are widely used not only as traditional jewelleries but also as useful components in a variety of well known advanced materials such as electrical and electronic devices, catalysts and medical instruments. On one hand the availability of gold is very limited; on the other hand, a substantial proportion of this valuable metal is generally discarded in the form of aqueous by-products during metal refining as well as the disposal of obsolete electronic devices. Thus, effective and economical recovery processes related to gold extraction/recycling from primary and secondary resources require urgent development. Recently, sorption processes based on low cost and widely available biomass materials is considered one of the most promising sustainable technologies that can be used for the recovery of gold from dilute solutions. In the last 3 years, we have made major advancements in our biosorption research, publishing more than 30 papers in refereed high impact-factored international journals, such as Bioressource Technology, Chemical Engineering Journal, Industrial & Engineering Chemistry Research, Green Chemistry, Journal of Chemical & Engineering Data, Journal of Hazardous Materials, Hydrometallurgy, Solvent Extraction and Ion Exchange, RSC Advances, etc. We have also published over 10 refereed conference proceeding papers related to this research in world-class conferences such as TMS, CIM/MetSoc, IEX, ALTA, etc. With this tremendous progress made in biosorption research within the last 3 years, we are now well prepared to move forward to extend our research in this field of hydrometallurgy. The objectives of the proposed research program would be to lay a scientific foundation for the development of cost-effective, sustainable and efficient recovery processes for extracting gold from dilute solution using biomaterials prepared from biomass wastes. The currently most adopted technique for leaching gold from gold ore remains leaching in aqueous alkaline cyanide solutions. Recently, Barrick Gold Corporation adopted alkaline thiosulphate processing of gold in their successful demo-plant operation, although thiosulphate cannot completely replace cyanide, it could provide an alternative to cyanide. Following our successful research work on gold recovery from acidic solution through our previous Discovery Grant, in our proposed research we plan to extend our work to the recovery of gold from alkaline solutions of cyanide and thiosulphate, in order to meet industry’s urgent needs. In this research, gold will be recovered from a dilute alkaline solution in a batch reactor using chemically modified cellulosic biomaterials. Initially commercially available pure cellulose, after pre-treatment with sulphuric acid followed by grafting unique functional groups, will be used to develop a kinetic and adsorption isotherm model. Later bioadsorbents will be prepared from cellulosic biomass wastes such as waste paper, waste cotton and waste wood/saw dust that will be tested for gold sorption from real solution. Those biomass wastes are abundantly available and will be a cheap source of raw materials for making bioadsorbents. Proper use of such biomass wastes as value-added products will not only reduce the volume of wastes being generated every day, but will also have high end value to the gold mining industry as this cheap bioadsorbent will have superior performance over the traditionally used activated carbon. Both mining and waste management companies will benefit from this research. The proposed research program will train 4 M.Sc., 1 Ph.D., 5 post-docs and 4 undergraduate students in the area of extractive metallurgy.