【Ten Years of Great Progress in Chemical Engineering Technology】027-2023: Multi-product Production Technology for High-modulus Water Glass via the Separated Preparation of Aluminum and Silicon from Gasification Slag on a Thousand-ton Scale

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China’s annual emissions of gasification slag exceed 50 million tons. This slag presents various challenges in terms of high levels of toxic components and impurities, low reactivity, and difficulties in comprehensive utilization. The comprehensive utilization rate in the large energy bases in the northwest is less than 10%, and hundreds of millions of tons of such slag are stored across the country, causing severe pollution of water, soil, and air. The large-scale and efficient utilization of this slag is a critical issue that needs to be addressed urgently by the industry. Building on years of research in the high-value utilization of coal-based solid waste, the Green Processes and Circular Economy Technology Team at the Institute of Process Engineering, Chinese Academy of Sciences, began in 2016 to carry out innovative research on the large-scale high-value utilization of coal gasification slag. This technology overcomes key challenges such as the mechanochemical synergistic activation and coupled removal of impurities from gasification slag, the iron removal and detoxification of activation solutions for the production of polyaluminum chloride (PAC), and the control of oligomer structure in dilute alkali systems to produce high-modulus water glass. It enables the high-value utilization of aluminum and silicon contained in gasification slag, as well as the green and low-carbon production of high-modulus water glass through entirely wet-process methods. Pilot tests on a scale of one thousand tons have been carried out; according to third-party tests, the modulus of the resulting water glass reached 3.53. This approach provides a new pathway for circular economy applications in the large-scale value addition of coal gasification slag. The Institute of Process Engineering, Chinese Academy of Sciences, in collaboration with Sinopec Ningbo Research Institute Co., Ltd., carried out pilot-scale tests on a thousand-ton scale to produce water glass with high modulus and low impurities, thereby achieving for the first time the green and low-carbon production of high-modulus water glass as a bulk chemical product using entirely wet-process methods. Based on the pilot plant data and the technical details presented at the project evaluation meeting, the comprehensive utilization rate of gasification slag is >95%, with a reduction in CO₂ emissions of over 50%. In addition, an application solution for the large-scale high-value utilization of 2,000 tons per year of gasifier slag (on a wet basis) has been developed, which can support the construction of demonstration projects for the large-scale high-value utilization of 200,000 tons per year of gasifier slag. In March 2023, the project \"Multi-product Production Technology for High Modulus Water Glass via Separated Preparation of Aluminum and Silicon from Coal Gasification Slag on a Thousand-ton Scale\", carried out in collaboration between the Institute of Process Engineering of the Chinese Academy of Sciences and Sinopec Ningbo Research Institute Co., Ltd., successfully passed the evaluation of scientific and technological achievements organized by the China Petroleum and Chemical Industry Federation. The evaluation committee for this project is headed by Academician Fei Weiyang from Tsinghua University, with Academician Chen Yong from the Guangzhou Institute of Energy, Chinese Academy of Sciences, serving as deputy chairman. Seven other experts, including Researcher Lv Qinggang from the Institute of Engineering Thermophysics, Chinese Academy of Sciences, serve as members of the committee. The evaluation committee unanimously agreed that the overall technology of the project has reached an internationally advanced level, with the aforementioned innovative technologies being at an internationally leading level; it is recommended to accelerate the industrialization of these technologies.