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，而且还被用作各种知名先进材料的有用部件，如电气和电子设备、催化剂和医疗器械。一方面，黄金的可获得性非常有限；另一方面，在金属精炼和废弃电子设备处理过程中，这种有价值的金属中的相当大一部分通常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/再循环黄金有关的有效和经济的回收工艺。近年来，基于低成本和广泛使用的生物质材料的吸附过程被认为是最有前途的可持续技术之一，可以用于从稀溶液中回收金。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、溶剂提取与离子交换、RSC进展等高影响力的国际期刊上发表了30多篇论文。我们还在TMS、CIM/MetSoc、IEX、ALTA等世界级会议上发表了10多篇与本研究相关的论文。我们现在已经做好了充分的准备，以扩大我们在这一湿法冶金领域的研究。拟议研究方案的目标将是为开发具有成本效益、可持续和高效的回收工艺奠定科学基础，以利用生物质废物制备的生物材料从稀溶液中提取金。目前采用最多的从金矿中浸出金的技术仍然是在碱性氰化物水溶液中浸出。最近，巴里克黄金公司在其成功的示范工厂运营中采用了碱性硫代硫酸盐提金，尽管硫代硫酸盐不能完全取代氰化物，但它可以提供一种氰化物的替代品。继我们通过之前的发现基金成功地从酸性溶液中回收金的研究工作之后，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金，以满足行业的迫切需求。在这项研究中，将在间歇反应器中使用化学修饰的纤维素生物材料从稀碱溶液中回收金。首先，商业上可获得的纯纤维素，经过硫酸预处理，然后接枝独特的官能团，将被用于开发动力学和吸附等温线模型。稍后将从废纸、废棉和废木/锯末等纤维素生物质废物中制备生物吸附剂，并测试它们对真实溶液中的金的吸附能力。这些生物质废物大量可用，将成为制造生物吸附剂的廉价原材料来源。适当利用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，而且还将对黄金开采行业产生高端价值，因为这种廉价的生物吸附剂将具有优于传统使用的活性碳的性能。矿业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提取冶金领域的4名硕士、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.