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The industry-leading technology for producing acid from sulfur foam and desulfurization waste liquids using a combined dry-wet method – Author/Source: Sinochem New Network, Date: May 16, 2023, Clicks: 18. On May 12, the technology for producing acid from sulfur foam and desulfurization waste liquids via a combined dry-wet method, developed by Jiangsu Minglang Environmental Technology Co., Ltd., passed the expert evaluation conducted by the China Coking Industry Association in Lianyungang, Jiangsu. The expert group agreed that this technology uses thick and high-precision filtration methods to treat sulfur foam, and process separation techniques to remove high-melting-point impurity salts; it has resulted in one patented technology and two proprietary technologies, which are the first of their kind in China and represent an advanced level in the industry. An expert group led by Shi Yanfeng, president of the China Coking Industry Association, pointed out that this technology has lower comprehensive energy consumption and dilute acid yield compared to similar process technologies. Segmented feeding of sulfur powder and concentrated desulfurization waste liquid is used, and the combustion method is scientific and reasonable ； The feed rate of the concentrated desulfurization waste liquid can be flexibly controlled based on the salt content of the desulfurization solution. This technology has a wide range of applications and high promotional value. It is reported that this technological achievement was successfully applied in July 2022 in an acid production project capable of processing 20,000 tons per year of gas desulfurization waste liquid, as part of a coking plant with a capacity of 2.15 million tons per year in a company in Shanxi. After more than 8 months of stable operation, all technical parameters met the design requirements and the expected outcomes were achieved. It is understood that in our country, over 600 million tons of coking coal are used each year for high-temperature coking, with a sulfur content of around 1%. During the coking process, 30% to 40% of this sulfur ends up in the coke oven gas. There are various methods for desulfurizing coke oven gas, and the wet catalytic oxidation method is widely used in the metallurgical coking industry due to its high desulfurization efficiency and low operating costs. However, if the sulfur foam and desulfurization wastewater generated by the wet catalytic oxidation method are not properly disposed of, it will result in 1.8 to 2.4 million tons of sulfur pollutants per year, as well as 3 to 5 million tons of desulfurization wastewater pollution. QQScreenshot20230515143006.jpg Gao Zhidou, chairman of Jiangsu Minglang, explained that initially, most companies in the industry added desulfurization waste liquid to the coal used in production; this not only created a cycle of sulfur within the system but also increased the burden of desulfurization for coke oven gas ； And it severely affects the quality of coke. Later, some companies switched to using sulfur desulfurization waste liquid to extract salt; this method not only required high energy consumption and caused severe pollution, but the salt obtained was also difficult to sell due to quality issues. As a result, the technology of extracting salt from desulfurization waste liquid was gradually phased out by the market. Meanwhile, the method of producing sulfur by melting sulfur in foam has been abandoned by the industry due to its high energy consumption during processing, high generation of by-products, severe secondary pollution, and low purity of the resulting product. Gao Zhidou believes that by using scientific and reasonable methods to handle these sulfur foams and desulfurization waste liquids, it is possible not only to achieve the resource utilization, reduction, and harmless treatment of hazardous waste, thus turning waste into treasure ； More importantly, it can improve the absorption efficiency of the desulfurization liquid, ensuring effective desulfurization of coke oven gas. It is reported that currently, the main processes for producing acid from domestic coking desulfurization wastewater and sulfur foam include wet acid production, dry acid production, and semi-dry/semi-wet (liquid sulfur) acid production, among others. These technologies all have certain advantages, but their disadvantages are also quite obvious, causing confusion for businesses. The main issue is that some dilute acids have a high production volume, which is difficult for customers to accept ； Some have high energy consumption and cause severe secondary pollution ； Some are prone to clogging and cannot operate stably over long periods of time ； Some also generate hazardous waste, and so on. In light of the current situation regarding coking desulfurization and waste liquid treatment in China, Jiangsu Minglang, in collaboration with research institutions such as Sinopec Nanjing Research Institute of Chemical Technology and Jiangsu Ocean University, utilized simulation software for the acid production process using coking sulfur foam and desulfurization waste liquids. Through laboratory and semi-industrial tests, along with the company’s years of practical experience in dealing with coking sulfur foam and desulfurization waste liquids, a comprehensive dry-wet method for producing acid from such materials was developed – a method that features low energy consumption for preprocessing and combustion, low output of dilute acid, no secondary process problems, and high process suitability ； It addresses the shortcomings in existing acid production processes and resolves the salt balance issue in desulfurization wastewater. A highly efficient, energy-saving, and environmentally friendly device has been developed; it features a simple processing process, low energy consumption, no adverse effect of the filtrate on desulfurization, and no steam requirement for the pretreatment of sulfur foam. This device not only achieves the goal of acid production but also integrates acid production with desulfurization, enabling them to complement each other. Gao Zhidou said that this technology holds significant practical value in promoting high-quality development characterized by resource conservation, environmental friendliness, and low carbon emissions; it also contributes to the survival, profitability, and growth of coking enterprises. Compared with other mainstream acid production processes, this technology offers significant economic and social benefits. The energy consumption cost per ton of concentrated sulfuric acid decreases by 80–170 yuan, while the overall energy consumption per ton of concentrated sulfuric acid drops by 110–120 kgec. Taking a coking plant with an annual production capacity of 2 million tons and an annual output of 30,000 tons of concentrated sulfuric acid as an example, this can save the enterprise between 2.4 million and 5.1 million yuan in energy costs per year. The overall energy consumption is reduced by 3,300 to 3,600 tec, resulting in a reduction of 8,800 to 9,600 tons of carbon dioxide emissions per year; at the same time, around 19,000 tons of sulfur dioxide are avoided from being released into the environment each year. It is understood that once this technology was developed successfully, it was highly favored by users. Currently under construction or in the design phase is the project by Shandong Leo New Energy Co., Ltd., which involves building an acid production facility capable of processing 10,000 tons per year of waste liquid resulting from gas desulfurization, as part of a 1 million tons per year coking plant ； Heilongjiang Jianlong Chemical Co., Ltd. constructed a 20,000-ton/year acid production facility using gas desulfurization waste liquid as a by-product of its 2 million tons/year coking operation; Shandong Rongxin Group Co., Ltd. built a 50,000-ton/year acid production facility using gas desulfurization waste liquid as a by-product of its 3 million tons/year coking operation, among other projects.