Review of new methods for resource utilisation of electrolytic manganese residue and its application in building materials

The storage of electrolytic manganese residue (EMR) has significantly hampered the growth of the electrolytic metallic manganese (EMM) industry. EMR harbours numerous harmful components, including ammonia nitrogen (NH3-N), soluble manganese, and heavy metals. EMR, if untreated, is typically left exposed in the open air, presenting a serious hazard to both the ecosystem and public health. This danger arises from the potential decomposition of soluble ammonium sulphate and other sulphates, which can emit harmful gases such as NH3 and SO2. The extensive accumulation of EMR contaminates surrounding soil and water bodies. Moreover, inhalation of heavy metals by humans could pose severe health risks. Managing and treating these wastes also significantly depletes financial resources. Over recent years, several resource utilisation techniques for producing unburnt bricks, geopolymers, road base materials, cement and cementitious materials, ceramics, and ceramsite using EMR have been proposed globally. However, these resource utilisation methods come with their own set of issues, including the ineffective control of NH3-N, high sulphate content, and questionable long-term durability performance. This situation has resulted in a dearth of mature, eco-friendly methods for utilising EMR. This study aims to evaluate the potential of using EMR in building materials. It reviews the development of EMM, the formation of EMR, its physical, chemical, and ecological characteristics, the analysis of its harmful components, and the current state of resource utilisation in building materials over the last 30 years. EMR has found applications in building materials such as cement and cementitious, road base materials, geopolymers, bricks, ceramics, and ceramsites. The advantages and disadvantages of various resource utilisation methods are examined and related challenges and prospects are discussed. Finally, we deliberate on the present challenges and future possibilities of EMR utilisation in the construction materials industry. It is our hope that this review will provide insights into addressing the challenge of resourceful use of EMR in construction materials, thereby contributing to the sustainable growth of the EMM industry.