Recycling of ironmaking and steelmaking slags in Japan and China

Abstract

The mass production of steel is inevitably accompanied by large quantities of slags. The treatment of ironmaking and steelmaking slags is a great challenge in the sustainable development of the steel industry. Japan and China are two major steel producing countries that have placed a large emphasis on developing new technologies to decrease slag emission or promote slag valorization. Slags are almost completely reused or recycled in Japan. However, due to stagnant infrastructural investments, future applications of slags in conventional sectors are expected to be difficult. Exploring new functions or applications of slags has become a research priority in Japan. For example, the utilization of steelmaking slags in offshore seabeds to create marine forests is under development. China is the top steel producer in the world. The utilization ratios of ironmaking and steelmaking slags have risen steadily in recent years, driven largely by technological advances. For example, hot stage processing of slags for materials as well as heat recovery techniques has been widely applied in steel plants with good results. However, increasing the utilization ratio of basic oxygen furnace slags remains a major challenge. Technological innovations in slag recycling are crucial for the steel industries in Japan and China. Here, the current status and developing trends of utilization technologies of slags in both countries are reviewed.

Evolution of Interface Characteristic between Quicklime and CaO–SiO2–FetO–MgO Melt during Slag‐Forming Procedure in Converter under Different Times

“…Lime dissolution is also related to the physical structure of lime itself and slag properties. [3][4][5][6][7] Generally, reducing the particle size of lime particles and increasing the lime porosity can increase their specific surface area and enhance the lime dissolution rate in slag. In the slag-forming route based on CaO component of the converter, the reaction interface between the early-stage slag and quicklime can reflect the degree of lime dissolution.…”

“…However, the majority of f-CaO in steel slag comes from the incomplete dissolution of lime. [3] The promotion of rapid dissolution and slagging of lime in slag is a very important and widely studied topic. Matsushima et al [4] used the rotating cylinder method to investigate the dissolution rate of lime particles in slag and found that the dissolution rate of lime increases with the increase in rotation speed and is linearly related to time.…”

Quantificação do fluxo de escória granulada por meio da equação do sistema INBA®

“…A mistura que escoa pela tela é direcionada para um reservatório, enquanto partículas de escória são removidas na parte superior usando "dentes" revestidos. Esse sistema é considerado uma tecnologia avançada, por proporcionar a obtenção de partículas de tamanho uniforme, alta qualidade e valor agregado elevado (MATSUURA et al, 2022). Ademais, oferece benefícios ambientais significativos, tais como a diminuição da emissão de gases de combustão e poeira do altoforno, e a diminuição da demanda por água durante o processo de resfriamento da escória (MATSUURA et al, 2022).…”

Determination of Fe3O4 Content and Total Nonhydraulic Minerals in Steel Slag

“…The steel slag is a by-product generated during the process of steel production in the industrial sector. As per the 2022 statistics from the National Bureau of Statistics, China's annual crude steel output has reached 1.018 billion tons, resulting in an annual production of 146 million tons of steel slag; however, its resource utilization rate remains below 30% [1,2]. During smelting, various pollutants present in iron ore inevitably transfer to the steel slag, leading to their accumulation and causing significant environmental pollution in the surrounding areas [3,4].…”