Shuhua Ma

Scenario Analysis of Sulfur Dioxide Emissions Reduction Potential in China's Iron and Steel Industry

Acid rain remains an important environmental problem. The Chinese steel industry is becoming a key domestic emitter of sulfur dioxide (SO), the central molecular component of acid rain. In this study SO emission potential is assessed by developing a material flow analysis (MFA) model and generating four different SO industry emission scenarios from 2006 to 2030, with each scenario representing a possible development path for the industry. When SO emission factors in every unit of steel production are presumed to remain constant through 2030, scenario analysis results show that under a business‐as‐usual (BAU) scenario SO emissions will experience sustained growth to a peak value of 1.73 million metric tons (megatons, Mt) through 2020, approximately 52% higher than that in 2006, and that this trend is unlikely to be reversed. The high scenario and medium scenario demonstrate that it is difficult to control SO emissions to an acceptable level by only upgrading technology and making industrial structural adjustments. Yet through the incorporation of sintering gas desulfurization, the low scenario can smoothly bridge the gap between the simulative SO emissions and the envisioned value, since sintering is the biggest emitter in this industry. Once the desulfurization rate of sintering gas reaches 60%, SO emissions will be less than the level of 0.60 Mt in 2030 and will also meet the reduction goals. Moreover, scenario analysis suggests that single terminal control cannot solve the problem of high SO emissions. Therefore, in order to control the total SO emissions of the steel industry it is imperative that two or more measures be combined.

Research and industrialization progress of recovering alumina from fly ash: A concise review

Fly ash, a by-product of high temperature combustion of coal in coal-fired power plants, is one of the most complex and largest amount of industrial solid wastes generated in China. Its improper disposal has become an environmental problem. Now it is widely realized that fly ash should be considered as a useful and potential mineral resource. Fly ash is rich in alumina, making it a potential substitute for bauxite. With the diminishing reserves of bauxite resources, as well as the increasing demand for alumina, recovery of alumina from fly ash has attracted extensive attention world-wide. The present review describes, firstly, the generation and physicochemical properties of high alumina fly ash found in northern China and then focuses on the various alumina recovery technologies, the advantages and disadvantages of these processes, and in particular, the latest industrial developments. Finally, the directions for future research are also considered.

Effects of particle size and coating on decomposition of alumina-extracted residue from high-alumina fly ash

The effective removal of alkali in the alumina-extracted reside (AER) obtained by extracting alumina from high-alumina fly ash is the premise for realizing the utilization of the silicon component in the fly ash. Sodium was removed from the AER by a decomposition reaction. The effects of the particle size and reactant coating on the decomposition reaction of AER were studied, and the results showed that by decreasing the particle size, the decomposition reaction rate of AER could be enhanced obviously and the Na2O content of the products could be decreased effectively. In addition, the process and mechanism of the decomposition reaction of AER and the reaction kinetics were investigated. The results revealed that the decomposition reaction of AER started from the outer surface of the AER particles. The reaction kinetics corresponded with shrinking unreacted core models. Furthermore, the decomposition reaction rate of AER could be enhanced obviously by decreasing the particle size because the effect of product layer diffusion was weakened when the particle size of AER was decreased.

Assessment of environmental risk for red mud storage facility in China: a case study in Shandong Province

Red mud storage facility (RM-SF) pollution remains a serious problem in China mainly due to the RM’s huge quantity, little recyclability, and high alkalinity. And, there is also a risk of dam failure because almost all RM-SFs are processed by damming. In order to address this challenge and improve the level of risk management, it is necessary to evaluate the environmental risk of RM-SFs systematically. So, this paper firstly designs a comprehensive evaluation index system with a three-level evaluation index in the terms of RM characteristics, RM-SF characteristics, ambient environment of RM-SF, the management of RM-SF, and the application aspect of RM by the analytic hierarchy process (AHP) method. Then, a case of RM-SF from a typical alumina production enterprise is studied according to this system, as is assisted by several experts from different fields when determining the weights of all indicators. The results show that the risk of selected RM-SF primarily depends on the former factors, that is, RM and RM-SF characteristics, while the contributions of the other factors are quite smaller.