Value Recovery from Metallurgical Slags

金属提取和回收工业产生大量的“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，储存在冶炼设施附近的堆或坑中。然而，由于更严格的环境法规、对资源的需求和经济因素的驱动，炉渣的回收利用得到了相当大的关注，并部分得到了实践。然而，该行业远未实现冶金渣的所有价值：每年超过6亿吨的矿物和相当于3400万吨煤的热能。本研究旨在从根本上理解和解决一些最关键的挑战，这些挑战将允许通过将炉渣转化为高价值产品的合适材料来回收炉渣的热和材料价值。该研究项目探索了炉渣在各种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，以从炉渣中回收有价值的元素。冶金炉渣的化学成分范围很广。因此，本研究计划的主要目标是了解炉渣的结晶行为，以及炉渣中不同元素的形态。这种研究预计将建立相关性，允许预测的重要参数，如结晶的程度和速度和矿物成分的最终炉渣从初始组合物和处理条件（如冷却速度，气体气氛等）。这些成果对于创建科学知识库以及提高行业实现炉渣所有价值并走向更可持续实践的能力都将具有极其重要的意义。长期的好处是更清洁的金属提取和回收行业，减少对地球资源的压力，并培养几个研究生和本科生在材料加工，废物处理和材料表征领域的专业知识。

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.