Resource Recovery and Remediation of Alkaline Wastes

全球钢铁、氧化铝精炼和燃煤发电等行业每年产生超过5亿吨的碱性(即漂白剂类)废物。这些废物目前以堆放或填埋的形式储存，可能会造成严重的环境危害。通过废物过滤的水对水生生物有毒，在移动和储存过程中产生的粉尘危害公共健康。这些风险可能需要几十年的时间才能消退。另一方面，碱性废物含有大量我们希望回收再利用的材料，特别是对未来技术至关重要的金属，如用于海上风力涡轮机的钢铁制造的钒，用于汽车燃料电池的锂和钴，以及对下一代太阳能发电系统至关重要的稀土元素。显而易见的解决方案是：利用回收锁定在废物中的资源的利润来支付修复污染的费用，这一解决方案受到挖掘储存的废物堆造成的环境破坏以及使用现有技术从废物中提取金属的费用的阻碍。提出该项目的团队最近进行的突破性试点研究表明，利用低成本、低能源的自然过程的力量可以解决问题。我们正在开发一种独特的“生物采矿”方法，以提高储存在废物中的资源溶解成流经它的水的速度。我们的试点试验表明，在垃圾堆上覆盖一层‘固体城市垃圾’(堆肥)是非常有效的推动这一过程。当水流过经过堆肥处理的废物时，钒等金属的浸出量是未经处理的垃圾的两倍以上。然后，金属溶液在重力作用下从垃圾堆底部流出。高浓度意味着使用现有技术从该溶液中提取金属变得可行，我们建议将这些技术作为该项目的一部分来实施。实际上，有价值的资源是在不挖掘废物的情况下被开采出来的。资源回收的好处与对环境的好处相匹配。堆肥层减少了现场产生的粉尘，并允许更多的二氧化碳渗透到堆体中，通过反应形成固体碳酸盐矿物，将大量二氧化碳锁定在堆体中。由于钒等元素既是污染物，又是资源，回收将消除碱性废物风化造成的污染。此外，风化的废物堆具有建立全国稀有的兰花丰富的植物群落的理想条件，使它们适合恢复以创造具有高保护价值的栖息地。为了将我们试验研究的极有希望的结果转化为优化的、行业准备的过程，我们必须更好地了解控制生物采矿的具体机制，并制定路线图，谈判在一个对环境保护有严格要求的现有行业实施新技术所面临的经济、立法、环境和社会挑战。我们建议的研究将同时处理这两个方面。综合方案：回收金属资源，同时抑制粉尘，增加碳封存和治理造成的污染，这将对我们项目中来自行业(塔塔钢铁、力拓和矿产工业研究组织)和环境保护(环境局)的合作伙伴非常有利。该项目将把主要的商业合作伙伴与一个由环境科学家、废物政策专家和系统分析和利益相关者参与的多学科团队聚集在一起，为转变资源回收和环境补救铺平道路。该团队将调查这一转变的关键障碍，并确定可能的补救措施，例如游说修改立法或为资源回收提出明确的商业理由。

Over half a billion tonnes of alkaline (i.e. bleach-like) wastes are produced globally each year by industries such as steel production, alumina refining and coal-fired power generation. These wastes are currently stored in piles or landfill and can pose serious environmental hazards. Water that filters through the waste is toxic to aquatic life and dust generated as it is moved and stored is a public health hazard. It can take decades for these risks to fade. On the other hand, alkaline wastes contain large quantities of materials we would like to recover for re-use, particularly metals important to the technologies of the future, such as vanadium, used in steel manufacture for offshore wind turbines, lithium and cobalt for vehicle fuel cells and rare earth elements crucial for next-generation solar power systems. The obvious solution: using the profits from recovering resources locked in the waste to pay for remediation of the pollution, is hampered by the environmental damage caused by digging up stored waste piles and the expense of extracting the metals from the waste using existing technology.Ground-breaking pilot research recently conducted by the team proposing this project shows that harnessing the power of low-cost, low-energy natural processes could solve the problem. We are developing a unique 'biomining' approach to increase the rate at which resources stored in the waste dissolve into water passing through it. Our pilot tests have shown that covering the waste pile with a layer of 'solid municipal waste' (compost) is very effective in driving this process. As water flows through waste treated with compost, metals like vanadium leach out to levels over twice those of untreated piles. The metal solution then flows out of the bottom of the waste pile under gravity. The high concentrations mean that extracting metals from this solution becomes viable using existing technology which we propose to implement as part of this project. In effect the valuable resources are extracted without digging up the waste.The resource recovery benefits are matched by benefits to the environment. The layer of compost reduces dust generation from the site, and allows more CO2 to penetrate into the pile where it is locked away in significant quantities by reacting to form solid carbonate minerals. As elements like vanadium are pollutants as well as resources, recovery will eliminate the pollution alkaline waste weathering causes. Furthermore, the weathered waste piles have ideal conditions for nationally-scarce, orchid-rich plant communities to become established, making them suitable for restoration to create habitat of high conservation value.In order to turn the extremely promising results of our pilot studies into optimised, industry-ready processes we must better understand the specific mechanisms which control the biomining and develop a road map for negotiating the economic, legislative, environmental and societal challenges to the implementation of a new technology in an established industry with strict requirements for environmental protection. Our proposed research will tackle both these aspects in parallel. The combined package: recovery of the metal resources while suppressing dust, increasing carbon sequestration and treating the pollution caused, would be hugely beneficial to partners in our project from both industry (Tata Steel, Rio Tinto and the Minerals Industry Research Organisation) and environmental protection (Environment Agency).The project will bring together key commercial partners with a multi-disciplinary team of environmental scientists, waste policy experts and specialists in systems analysis and stakeholder engagement to pave the way for transforming resource recovery and environmental remediation. This team will investigate the key obstacles to this transformation and identify potential remedies, such as lobbying for legislative change or making a clear business case for resource recovery.