The purification technology for gasification slag has been successfully applied

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Successful Application of Gasification Slag Purification Technology Author/Source: Gasification World Date: 11-17-2021 Clicks: 6 Recently, the gasification slag purification technology developed by Shaanxi Rongtai Energy Holding Co., Ltd. was put into industrial use at Shanxi Coal Pucheng Clean Energy Chemical Co., Ltd. The 300,000 tons per year industrial demonstration plant for the comprehensive utilization of gasified fine slag is currently operating stably. It is expected to produce around 70,000 tons of refined coal per year and reduce waste residue emissions by more than 120,000 tons, yielding significant economic and social benefits. This technology primarily uses purification and dehydration processes to remove the unburned carbon remaining in the gasified fine slag, thereby eliminating the ash and moisture contained in the slag. The main process involves purifying and separating the waste sludge and black water generated by the gasification unit using a patented device developed by Rongtai Energy, after which the black water is returned to the gasification sedimentation tank. The material after one purification step is further separated; the resulting refined coal is sent to a dewatering device for solid-liquid separation. After drying and dehydration, it becomes the final product in the form of refined coal. A responsible official from Pu Jieneng Chemical said that the carbon content in the gasification slag is 30%~50%; after treatment, the carbon content in the waste residue drops below 10%, resulting in reduced emissions of solid waste and gasification wastewater, with over 200 tons of high-quality coal produced each day. This type of coking coal has a fixed carbon content of 70% to 90%, with a calorific value of 4500 to 6000 kcal. Due to its much higher carbon content compared to the raw coal, it can be used directly as a gasification feedstock or as thermal coal, thereby significantly reducing the cost of coal procurement. Furthermore, after high-temperature reaction in the gasification furnace, the purified bituminous coal contains almost no nitrogen or sulfur. When used as fuel in boilers, emissions of sulfur dioxide and nitrogen oxides are near zero, which significantly reduces the operating costs of boiler desulfurization and denitration systems, resulting in notable energy savings and carbon reduction. It is understood that gasification, as the key process in coal chemical industry, generates large amounts of fine and coarse slag that are difficult to utilize comprehensively. The vast majority of enterprises in China dispose of this slag by landfilling, which not only poses a risk to environmental pollution but also incurs additional costs. Compared with gasified fine slag, although the carbon content of coarse slag is lower, its quantity is 3 to 4 times that of the fine slag, giving it greater potential for comprehensive utilization. Currently, Shaanxi Rongtai Energy Company is working on developing technology for the treatment of gasification slag.