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的珠宝，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，黄金的可得性非常有限；另一方面，在金属精炼和废弃电子设备的处理过程中，这种贵重金属的很大一部分通常以含水副产品的形式被丢弃。因此，迫切需要发展与从初级和次级资源中提取/再循环黄金有关的有效和经济的回收方法。最近，基于低成本和广泛可用的生物质材料的吸附工艺被认为是最有前途的可持续技术之一，可用于从稀溶液中回收金。在过去的三年里，我们在生物吸附研究方面取得了重大进展，在生物资源技术，化学工程杂志，工业与工程化学研究，绿色化学，化学与工程数据杂志，危险材料杂志，湿法冶金，溶剂萃取和离子交换，RSC进展等高影响因子的国际期刊上发表了30多篇论文。在TMS、CIM/MetSoc、IEX、ALTA等国际一流会议上发表了10余篇与本研究相关的论文。随着生物吸附研究在过去三年中取得的巨大进展，我们现在已经准备好继续扩大我们在湿法冶金领域的研究。拟议的研究方案的目标是为开发具有成本效益、可持续和有效的回收工艺奠定科学基础，以便利用从生物质废物中制备的生物材料从稀溶液中提取金。目前从金矿中浸出金的主要方法是在碱性氰化物溶液中进行浸出。最近，巴里克黄金公司在其成功的示范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。在我们通过之前的发现基金成功地研究了从酸性溶液中回收黄金之后，我们计划在我们提出的研究中扩展我们的工作，以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，金将从稀释碱性溶液中回收，在间歇式反应器中使用化学修饰的纤维素生物材料。最初市售的纯纤维素，经过硫酸预处理，接枝独特的官能团，将用于建立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、废棉花和废木材/锯末）中制备生物吸附剂，并对其从实际溶液中吸附金进行测试。这些生物质废料储量丰富，将成为制造生物吸附剂的廉价原料来源。适当地利用这些生物质废物作为增值产品，不仅可以减少每天产生的废物量，而且对金矿开采行业具有高端价值，因为这种廉价的生物吸附剂比传统使用的活性炭具有更优越的性能。采矿和废物管理公司都将从这项研究中受益。该研究项目将培养4名冶金学硕士、1名博士、5名博士后和4名本科生。

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.