Supercritical Carbonation for Stabilisation and Reuse of Hazardous Wastes

超临界碳酸化用于危险废物的稳定和再利用

• 批准号: EP/I00646X/1
• 负责人: Leon Black
• 金额: $ 14.68万
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2011
• 资助国家: 英国
• 起止时间: 2011 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FI00646X%2F1
• 关键词: Supercritical; Carbonation; Stabilisation; Reuse; Hazardous

Supercritical carbonation has been identified as an innovative technique to treat air pollution control (APC) residues, a particularly troublesome class of hazardous wastes. Treatment enables them to be either safely disposed of or re-used as artificial aggregates in building materials. Contrary to other technologies available, the technique converts the powdered residues to a solid block whilst also immobilising heavy metals with minimal energy input. An additional benefit is that the process captures carbon dioxide in a geologically stable form. The purpose of this project is to develop a commercially viable method for the carbonation of APC residues, reducing the costs of disposal for waste management companies and generating a saleable product for the construction industry. Energy from waste (EfW) facilities are an increasingly favoured Waste Management option. However, trapping of the resultant emissions produces APC residues which are classed as hazardous materials. These environmental concerns make an acceptable waste management strategy imperative. However, to date, suitable treatment methods are limited. Accelerated carbonation has been proposed as a treatment method for APC residues, with carbonation of a powdered material being achieved in a matter of hours or days. The formation of geologically stable carbonates has been shown to immobilise many of the problematic heavy metals, including lead and zinc. However, accelerated carbonation still has drawbacks, namely incomplete carbonation, a powdered or granular product and slow reaction kinetics. Super-critical carbonation technology however will provide all of the benefits of accelerated, sub-critical, carbonation, whilst also overcoming its limitations. Carbonation will neutralise and solidify the powdered wastes, whilst immobilising many of the key components of environmental concern as stable carbonates. What's more, the process also immobilises carbon dioxide in a geologically stable chemical form within the stabilised residues. At 78.1 atm and 31oC carbon dioxide becomes supercritical, having the density of a liquid, but the permeability of a gas. The combination of high gas density and ability to permeate sub-micron sized pores ensures rapid carbonation. Furthermore, whilst with conventional carbonation both the starting and end products are powdered or granular, the ability of supercritical CO2 to penetrate small pores enables monolithic samples to be treated, overcoming problems associated with the handling of fine powders. By varying the solid-liquid ratio of a lime-based solid, i.e. APC residues, it is possible to control the solid's porosity, with high ratios giving greater porosity.Super-critical carbonation is a proven technology, having been shown to improve the technical properties of many calcium-rich materials, with reduced porosity and increased strength associated with the pore filling by carbonate species. The technology however has never previously been applied to the treatment of waste materials, in particular APC residues. The use of super-critical carbonation technology for the stabilisation and solidification of APC residues will provide a cost-effective means of treating these troublesome wastes. The benefits of this approach are;1. The conversion of an alkaline fine powder to a neutral solid block.2. More rapid and extensive carbonation than accelerated carbonation.3. Immobilisation of the heavy metals present in APC residues, particularly lead and zinc, as insoluble carbonates.4. Requires no additional material other than water and carbon dioxide (CO2).5. Does not require high temperatures and so is a relatively low energy approach.6. Chemically binds carbon dioxide within the stabilised blocks.We have identified two commercial routes to market; avoidance of landfill and the production of alternative construction materials. We are working with a number of companies to realise these aims.

超临界碳酸化技术是一种处理大气污染控制残留物（APC）的创新技术，APC是一类特别棘手的危险废物。处理使它们能够安全地处置或作为建筑材料中的人工骨料重新使用。与其他可用技术相反，该技术将粉末状残留物转化为固体块，同时还以最少的能量输入固定重金属。另一个好处是，该过程以地质稳定的形式捕获二氧化碳。该项目的目的是开发一种商业上可行的APC残留物碳酸化方法，降低废物管理公司的处置成本，并为建筑行业生产可销售的产品。废物能源（EfW）设施是越来越受欢迎的废物管理选项。然而，捕获所产生的排放物会产生APC残留物，这些残留物被归类为危险材料。这些环境问题使一个可接受的废物管理战略势在必行。然而，到目前为止，合适的治疗方法是有限的。已经提出加速碳酸化作为APC残留物的处理方法，其中粉末材料的碳酸化在几小时或几天内实现。地质稳定的碳酸盐的形成已被证明可以固定许多有问题的重金属，包括铅和锌。然而，加速的碳酸化仍然具有缺点，即不完全的碳酸化、粉末状或颗粒状产物和缓慢的反应动力学。然而，超临界碳酸化技术将提供加速的亚临界碳酸化的所有益处，同时还克服其局限性。碳酸化将中和和固化粉末状废物，同时将许多环境问题的关键成分固定为稳定的碳酸盐。更重要的是，该过程还将二氧化碳以地质稳定的化学形式固定在稳定的残留物中。在78.1大气压和31 ℃下，二氧化碳变成超临界状态，具有液体的密度，但具有气体的渗透性。高气体密度和渗透亚微米尺寸孔隙的能力的组合确保了快速碳酸化。此外，虽然在常规碳酸化中，起始产物和最终产物都是粉末状或颗粒状的，但超临界CO2渗透小孔的能力使得能够处理整体样品，克服了与处理细粉末相关的问题。通过改变石灰基固体（即APC残渣）的固液比，可以控制固体的孔隙率，高比例可提供更大的孔隙率。超临界碳酸化是一种成熟的技术，已被证明可以改善许多富钙材料的技术性能，降低孔隙率并增加与碳酸盐物质填充孔隙相关的强度。然而，该技术以前从未应用于废料处理，特别是APC残留物。使用超临界碳酸化技术来稳定和固化APC残留物，将为处理这些棘手的废物提供一种具有成本效益的方法。这种方法的好处是：1。将碱性细粉转化为中性固体块。2.比加速碳化更迅速和广泛的碳化。固定APC残留物中存在的重金属，特别是铅和锌，作为不溶性碳酸盐。4.除了水和二氧化碳（CO2），不需要额外的材料。5.不需要高温，因此是一个相对低的能量方法。6.通过化学方法将二氧化碳固定在稳定的块体中。我们已经确定了两条进入市场的商业路线;避免填埋和生产替代建筑材料。我们正在与多家公司合作，以实现这些目标。