MATERIALS 5R BY INDUSTRIAL SYMBIOSIS IN THE CEMENT INDUSTRY - UNDERSTANDING METABOLISM OF TOXIC METALS IN CO-PROCESSING

波特兰水泥传统上是由石灰石和粘土在窑中高温加热制成的。在全球范围内，水泥生产约占造成气候变化的二氧化碳排放量的7%，并消耗了超过50亿吨的原材料。近年来，越来越多的趋势是用工业废料代替水泥生产中使用的燃料和矿物。这种做法有助于保护化石燃料和自然矿产资源。一般来说，现在进入水泥窑的废物主要含有可燃材料，并且与天然水泥原料中存在的无害元素相同，因此对水泥质量和环境没有不良影响。然而，有人建议，一些含有有毒金属的废物可以用于水泥窑，我们需要更多地了解这些潜在污染物在水泥生产和使用过程中发生了什么，以决定这些废物是否可以安全地添加到水泥窑中。因此，英国伦敦大学学院环境工程研究人员与中国建材研究院和华南理工大学的材料科学家合作，旨在对未经处理的废物中有毒金属的命运和行为进行科学研究，通过水泥窑，水化水泥膏和环境。我们将使用先进的化学分析和材料表征技术，包括使用来自英国钻石光源的高能x射线的x射线吸收光谱，以及北京同步加速器，来观察金属在通过窑和向水泥中加水时的形态变化，并了解在发生不良影响之前可以安全地添加多少含金属废物。在这项工作中获得的新认识将支持工业和政府关于利用废物制造水泥的决策。

Portland cement is traditionally manufactured by heating limestone and clay at high temperature in a kiln. On a global scale, cement production is responsible for about 7% of the CO2 emissions that we suspect of causing climate change and consumes more than 5,000,000,000 tonnes of raw materials. In recent years, there has been an increasing trend towards replacing both the fuels and minerals used in cement production with industrial wastes. This practice helps to conserve both fossil fuels and natural mineral resources. In general, wastes now fed to the cement kiln contain mainly combustible materials and the same harmless elements that are present in natural cement raw materials, so there is no undesirable effect on cement quality or the environment. However, it has been suggested that some wastes containing toxic metals could be used in cement kilns, and we need to know more about what happens to these potential pollutants during cement production and use, to decide whether such wastes can safely be added in the cement kiln. This collaboration between researchers in Environmental Engineering at University College London in the UK and Materials Scientists at the China Building Materials Academy and South China University of Technology therefore aims to conduct a scientific study of the fate and behaviour of toxic metals from untreated wastes, through the cement kiln, to hydrated cement pastes and the environment. We will use advanced techniques for chemical analysis and materials characterisation, including x-ray absorption spectroscopy with high energy x-rays from the UK's Diamond Light Source, and the Beijing Synchrotron, to see how the form of metals changes as they pass through the kiln and when water is added to the cement, and to understand how much metal-bearing waste can safely be added before undesirable effects occur. The new understanding gained in this work will support decision-making by industry and the government, about the use of waste in making cement.