Sustainable Recovery of Gold using Biomass Wastes in an Alkaline-Acidic Hybrid System

在碱性-酸性混合系统中利用生物质废物可持续回收黄金

• 批准号: RGPIN-2020-06989
• 负责人: Alam, Shafiq
• 金额: $ 2.4万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=746761
• 关键词: Sustainable; Recovery; Gold; using; Biomass

The gold processing industry extracts gold by leaching ore in cyanide solution followed by adsorption on activated carbon and electrowinning. However, both cyanidation and carbon adsorption have some major problems. Since cyanide is very toxic, gold plants are forced to destroy the cyanide in effluent that results in loss of expensive cyanide and increase in the overall operating cost. On the other hand, activated carbon, which is manufactured at 600-1200 oC, is expensive and it is not selective to gold only, hence further refining is necessary to produce pure gold. Also, during adsorption, gold is trapped inside the micro-pore of activated carbon that requires high temperature elution to reactivate the carbon. As a result, manufacturing and regenerating of activated carbon represents a major portion of the operating cost in a mining operation. Also, it releases greenhouse gases to the environment. To overcome these problems, in 2011, I started my NSERC Discovery research program to develop an innovative and sustainable gold recovery technology. In our process, gold was recovered from aqueous solution by biosorption on our adsorbents having novel functional groups. These adsorbents were prepared in a very simple process by crosslinking different biomass wastes with sulphuric acid at 100 oC. Biosorption is a new field in hydrometallurgical research, and since 2011, we made tremendous advancement in this area, generating 67 publications in high quality journals and in world-class conference proceedings. From this research, we found some remarkable results, such as: 1) unlike activated carbon, only gold is adsorbed on our novel bioadsorbents, hence no further treatment is necessary for impurity removal; and 2) when gold is adsorbed on our novel bioadsorbent, it is simultaneously reduced to metallic gold. These ground-breaking findings will make gold recovery much simpler, more cost-effective and energy efficient because no stripping, high temperature elution, and electrowinning are necessary. However, we observed that simultaneous adsorption-reduction of gold on our novel bio-adsorbents only takes place in acidic chloride media but not in alkaline cyanide solutions. Considering the urgent need to improve the gold cyanidation process, in the proposed research, I plan to recover gold using our novel bioadsorbents in an alkaline-acidic hybrid system where gold will be leached in an alkaline cyanide solution followed by acidification to recycle cyanide back to the leaching plant leaving behind gold in an acidic chloride media for simultaneous biosorption-bioreduction to produce pure gold. Our proposed biosorption process with recycling of toxic cyanide will ensure zero emission to the environment. This will eliminate the current practice of destruction of expensive cyanide in the effluent and result in huge cost savings for the industry and minimization of greenhouse gas emissions. Canadian mining companies will benefit from this innovative research.

黄金加工行业通过在氰化物溶液中浸出矿石来提取黄金，然后吸附在活性炭和电化上。但是，氰化和碳吸附都有一些主要问题。由于氰化物非常有毒，因此被迫在废水中破坏氰化物，从而导致昂贵的氰化物损失并增加整体运营成本。另一方面，以600-1200 OC制造的活性炭很昂贵，并且不仅可以选择黄金，因此需要进一步的精炼才能生产纯金。同样，在吸附期间，金被困在活性碳的微孔内，这需要高温洗脱才能重新激活碳。结果，活性炭的制造和再生是采矿业务中运营成本的主要部分。此外，它还向环境释放温室气体。为了克服这些问题，2011年，我启动了NSERC Discovery Research计划，以开发一种创新且可持续的黄金恢复技术。在我们的过程中，通过对具有新功能组的吸附剂的生物吸附来从水溶液中回收黄金。这些吸附剂是在非常简单的过程中通过以100 oC的硫酸交联不同的生物量废物来制备的。生物吸附是水透明术研究的一个新领域，自2011年以来，我们在这一领域取得了巨大进步，在高质量期刊和世界一流的会议记录中产生了67个出版物。从这项研究中，我们发现了一些显着的结果，例如：1）与活化的碳不同，只有黄金吸附在我们的新型生物吸附剂上，因此无需进一步的治疗来清除杂质； 2）当黄金吸附在我们的新型生物添加物上时，它同时还原为金属黄金。这些开创性的发现将使黄金恢复变得更加简单，更具成本效益和能源效率，因为不需要剥离，高温洗脱和电力。但是，我们观察到，我们在新型的生物吸附剂上同时还原黄金仅在酸性氯化物培养基中发生，而在碱性氰化物溶液中不发生。考虑到迫切需要改善黄金氰化过程，在拟议的研究中，我计划在碱性酸性杂种系统中使用我们的新型生物吸附剂回收黄金，在该系统中，将在碱性氰化物溶液中浸出黄金，然后在酸化溶液中酸化以回收氰化物的后背以回收氰化物。浸出植物在酸性氯化物培养基中留下黄金，以同时产生生物吸附 - 产生纯金。我们提出的通过毒性氰化物回收的生物吸附过程将确保对环境的发射为零。这将消除当前在废水中破坏昂贵的氰化物的做法，并为该行业节省巨大的成本，并最大程度地减少温室气体排放。加拿大矿业公司将从这项创新的研究中受益。