Value Recovery from Metallurgical Slags

金属开采和回收工业产生了大量的“矿渣”，一种主要由石灰、二氧化硅和氧化铝等氧化物组成的熔融溶液。传统上，这种材料被视为废物，储存在靠近冶炼设施的堆或坑中。然而，由于环境法规的日益严格、对资源的需求和经济因素的推动，矿渣的回收利用已得到相当大的重视，并已部分实施。然而，该行业远未实现冶金渣的全部价值：每年可产生超过6亿吨的矿物和相当于3400万吨煤的热能。本研究旨在从基本角度理解和解决一些最关键的挑战，通过将炉渣转化为高价值产品的合适材料，从而使炉渣的热价值和材料价值得到恢复。研究项目探讨了炉渣在不同条件下冷却时的结构变化，使其转化为水泥原料和玻璃陶瓷等产品，同时将其热能转移到另一种介质中。此外，还将研究通过特定的冷却条件、添加其他材料或氧化/还原对炉渣进行改性，旨在从炉渣中回收有价元素。冶金渣的化学成分范围很广。因此，了解矿渣的结晶行为，以及矿渣中不同元素的形态是本研究项目的主要目标。这种调查预计将建立相关性，从而能够预测重要参数，如结晶的程度和速率以及最终炉渣的矿物成分，从初始组成和加工条件（如冷却速度、气体气氛等）。其成果对于建立科学知识库，以及提高行业实现炉渣全部价值的能力和迈向更可持续的实践都将具有特别重要的意义。长期的好处是更清洁的金属提取和回收工业，减少对地球资源的压力，并培养一些在材料加工，废物处理和材料表征领域具有专业知识的研究生和本科生。

The metals extraction and recycling industries generate vast amounts of “slag”, a molten solution consisting of mostly oxides such as lime, silica and alumina. Traditionally, the material was regarded as a waste, and stored in piles or pits close to the smelting facilities. However, driven by the more stringent environmental regulations, need for resources, and economic factors, the recycling of slag has gained considerable attention and is partially practiced. The industry is however far from realizing all the value of metallurgical slags: minerals exceeding 600 million tonnes and thermal energy equivalent to 34 million tonnes of coal, each year. The present study aims at understanding and addressing some of the most critical challenges from fundamental perspective that would allow recovery of both the thermal and material values of slags by converting them to suitable materials for high value products. The research program explores the structural changes in the slags when they are cooled under various conditions, to allow their conversion to products such as cement feedstock and glass ceramics, and at the same time, transfer their thermal energy to another media. Additionally, the modification of slag by specific cooling conditions, addition of other materials, or oxidation/reduction will be investigated, aiming to recover of valuable elements from slag. Metallurgical slags have a very wide range of chemical composition. It is therefore the primary objective of this research program to understand the crystallization behavior of slag, as well as the speciation of different elements in slag in a very fundamental level. Such investigation is expected to establish correlations that would allow prediction of important parameters such as extent and rate of crystallization and mineral constituents of final slag from the initial composition and processing conditions (e.g. cooling rate, gas atmosphere, etc). The outcomes will be exceptionally significant for both creating a scientific knowledge base, as well as advancing industry's ability to realize all the value of slag and move towards more sustainable practices. The long term benefits are a cleaner metal extraction and recycling industry, reduced pressure on the earth resources, and training several graduate and undergraduate students with expertise in the fields of materials processing, waste treatment, and materials characterization.