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Introduction to new technologies for soda ash production in China. In 1997, Qingdao Soda Industry Co., Ltd. carried out technical modifications on its brine purification system using the lime-ammonium carbonate method, thereby achieving continuous and automatically controlled lime addition in the brine purification process for the first time. The renovation of this system is carried out in three main steps: the first is to select a suitable pH meter ； Second, select a hydrocyclone sand separator lined with cast stone ； Third, use self-control valves. After the renovation, automated control of lime addition was achieved, improving the operating environment and process conditions for this procedure; this has played a significant role in the purification of brine. In December 2002, Qingdao Soda Ash Co., Ltd. conducted an evaluation of the system; it can save 392 tons of raw salt (on a 100%-basis) per year (based on a soda ash production capacity of 600,000 tons/year). 2. Belt filter: In early 2003, a delegation from the China Soda Ash Association visited Solvay Company and learned that belt filters have been used in the foreign soda ash industry for over 10 years. They offer advantages such as high processing capacity and low moisture content. This year, Zhongxin Chemical Co., Ltd., a newly established subsidiary of Zhongzhou Aluminum Industry Company in our country, will begin operations. Let’s wait and see how it performs. 3. Application of wash water nozzles in the wash water system of alkali filters: In traditional wash water systems for alkali filters, the water flow distribution on the filter drum is uneven, resulting in unstable salt washing effects. Drawing on foreign experiences in soda ash production and the use of nozzles in related industries, Qingdao Soda Ash Co., Ltd. developed a nozzle-based alkali-washing water system. This system turns the washing water discharged from the nozzles into a mist, thereby compensating for areas that are difficult to wash. As a result, water consumption was reduced and efficiency improved. The qualification rate of soda ash in terms of salt content (calculated based on low-salt soda ash) increased from 68% prior to the modification to 81.5%. 4. Application of the RF350V dry Roots vacuum pump in the caustic soda filtration system: In the 1980s, when three new caustic soda plants were built (Shandong Haihua, Tangshan Sanyou, and Lianyungang Alkali Plant), centrifugal vacuum pumps were used to replace traditional water-ring vacuum pumps, thereby enhancing the pumping capacity. In 2001 and 2003, Zigong Honghe Chemical Co., Ltd. installed two RF350V dry Roots vacuum pumps to replace the water-ring vacuum pumps. These pumps can achieve a vacuum level of 49 kPa, with a pumping speed of 197 m³/min and a rotational speed of 980 rpm. 7. YL-type paddle-type alkali cooling machine: The YL-2 type alkali cooling machine, developed under the organization of China National Chemical Equipment Corporation, was put to trial at Shijiazhuang Combined Alkali Plant in 1992. After 4–5 years of experimentation and improvements, it achieved stable operation in 1996. After being scaled up, it was implemented at the Zhanhua and Jilantai soda plants in Yunnan, where it performed well; its heat transfer coefficient reached 629 KJ/m2·h·°C, whereas that of rotary soda coolers is merely 150–250 KJ/m2·h·°C. Compared to fluidized-bed alkali coolers and rotary alkali coolers, the YL-type paddle-type alkali cooler has the advantages of light weight, small footprint, low investment, high heat transfer efficiency, and easy operation. 5. Two-step process for waste liquidized ash treatment: To increase the concentration of CaCl2 in the waste liquid and reduce the cost of the resulting calcium chloride, Tianjin Soda Plant has been conducting experiments on treating waste liquidized ash for many years. However, all these attempts have failed due to the low concentration of CaO in the lime milk. Through pilot tests in 2000, the reasons for the previous failures in waste liquid ash treatment were finally identified. A new two-step process for treating waste liquid ash was proposed. During the pilot tests, the concentration of the ash slurry reached 170–190 tt; in industrial trials, the CaO concentration in the ash slurry reached 155–160 n, which fully meets the requirements of production. 6. A method for producing scale-free calcium chloride by directly utilizing waste liquid from the ammonia-soda process and plate evaporators: Based on its original calcium chloride production process, Tangshan Alkali Industry Co., Ltd. made only minor modifications to it. The waste liquid from the ammonia-soda process is directly fed into a clarification tank for clarification; after being preheated to 70–90°C, it is directly introduced into the evaporation system without any further treatment. Vacuum evaporation is then carried out under a steam pressure of 0.3 MPa or lower (this method also works under higher steam pressures). This approach resolves the long-standing problem of scaling in the heating chambers of evaporators in conventional calcium chloride production processes. It addresses a key issue for the sustainable development of ammonia-soda process soda ash plants, provides the necessary conditions for the overall advancement of the calcium chloride industry, and also contributes significantly to marine environmental protection. 7. Development and application of the 24.5M improved clarifier: Zigong Honghe Chemical Co., Ltd. developed the 24.5M improved clarifier by making improvements to the Spauding clarifier. It is used for clarifying AP mother liquor. The clarification area is 471 m², and its effective volume is 2,780 m³. The sedimentation rate of this clarifier can exceed 0.5 m/h. As a result, the turbidity of the AP mother liquor decreased from 75 ppm to 65 ppm, while the water-insoluble matter content dropped from 0.0278% to 0.0265%. 8. The membrane planting technology applied to the treatment of AP mother liquor: In 2002, a membrane planting technology filter manufactured by Shanghai Mingtai Environmental Protection Engineering Co., Ltd. was used for treating the AP mother liquor at the Soda Ash Plant of Shaanxi Xinghua Group. The results were remarkable; the turbidity of the AP mother liquor could be reduced to below 10 PPM. 12. The XAZ-F backwash filter press is used for the treatment of AП mother liquor: The XAZ-F backwash filter press manufactured by Shandong Laiwu Coal Mining Machinery Factory has performed well in numerous soda ash plants; the moisture content of the filter cake can be less than 30%. 9. Externally cooled carbonation towers and the new process for soda ash production from shifted gas: After operating for several dozen hours, traditional internally cooled carbonation towers require periodic cleaning due to scaling on the cooling surfaces; thus, their operating cycle is relatively short. The external-cooling carbonization tower jointly developed by China Chengda Chemical Engineering Corporation and Zigong Honghua Plant moves the cooling section outside the tower, utilizing the density difference between the media inside and outside the tower to achieve natural circulatory heat exchange. The intercooler can be isolated from the tower body using an angle valve; only regular cleaning of the intercooler is required, allowing the tower body to operate continuously. Building upon the external-cooling carbonation tower, China Chengda Chemical Engineering Company, in collaboration with Shijiazhuang Soda Ash Plant, successfully developed a new technology for soda ash production from shifted gas in 1999. This technology integrates the features of both external-cooling carbonation towers and shifted-gas soda ash production methods; vertical sieve trays are employed at the upper end of the tower, allowing high-pressure ammonia shifted gas to directly enter the soda ash production tower. As a result, while the decarburization of the ammonia synthesis feed gas takes place, sodium bicarbonate is produced simultaneously. One process in the shifted-gas soda ash production can replace the three processes of decarburization, compression, and carbonation in the rich-gas soda ash production. This saves labor and energy, reducing costs by 100 yuan per two tons. Additionally, the crystallization of heavy soda ash produced via shifted-gas method is superior to that obtained through rich-gas method, thus making it possible to save steam during calcination. This technology is a first in the world and at the international leading level. The new conversion gas-based soda ash production technology has been implemented in nearly ten enterprises, including: Shijiazhuang Combined Soda Plant, Lengshuijiang Soda Plant, Fuzhou Yaolong Company, Henan Jinshan Company, Huai’an Wallrun Chemical Co., Ltd., Shanxi Fengxi Soda Plant, Sichuan Guanghan Company, etc. 10. New type of salting-out crystallizer and circulation pump: The new salting-out crystallizer and circulation pump, jointly developed by China Chengda Chemical Engineering Company, Zigong Industrial Pump Company, as well as Debang, Yaolong, and Shilian, overcome the design flaws of traditional circulation pumps. This results in a new type of salting-out crystallizer and circulation pump that features high production capacity per unit volume and large crystal sizes. 11. Energy-saving dry ammonium furnace: The dry ammonium furnace is a key piece of equipment used to dry wet ammonium chloride in the combined soda ash production process. Currently, the air distribution plates in similar domestic equipment generally adopt a straight-flow design, with the gas flowing directly toward the bed layer. This setup easily leads to channeling, clogging of small holes, and material leakage when the equipment is shut down ； There is also the use of side-flow wind caps; typically, 4–8 side holes are made in such caps, allowing gas to flow out horizontally. This can sweep across the entire plate surface, eliminating dead zones. However, the fluidization conditions are not ideal, and the structure is relatively complex, making it difficult to manufacture. The air distribution plate of the new dry ammonium furnace put into use by Shuanghuan Company in 1998 features a strip-shaped structure, serving as a lateral air outlet channel. Thanks to a reasonable porosity and uniform gas distribution, the resistance across the distributor plate is reduced, resulting in significantly improved bed fluidization and high thermal energy utilization efficiency. Compared to similar equipment, the exhaust gas outlet temperature is lowered by 15–20°C. For feeding, this equipment employs direct top-down feeding, ensuring even distribution of wet ammonium and preventing blockages and caking of the material. It can dry wet ammonium chloride with a moisture content of 7.5%, with a capacity of 300 tons per day. Compared to the original dry ammonium furnace, it saves 15% energy, produces less dust, offers greater operational flexibility, and reduces the labor intensity for workers. 12. Technology for extracting natural soda ash from tailings using circulating hot water: This technology was put into operation by Natural Soda Ash Co., Ltd. in 1999, and it was successful on its first trial run. It utilizes the plant’s circulating hot water to extract Na2CO3 from low-grade tailings ore (where Na2CO3 content is ≤8%). First, select an appropriate bulk volume for the alkali ore, and then use hot circulating water at 40–50°C to fully dissolve the useful components in the natural alkali ore. This technology represents a breakthrough in the methods used for developing and utilizing low-grade alkali ores, increasing the utilization rate of such ores from 78.4% to 93.8%, with the alkali content in the waste sand being 3%. 13. Utilization of the mother liquor from natural soda ash production for baking soda: In 1999, Yuanxing Natural Soda Ash Company utilized the Na2CO3–NaHCO3–Na2SO4–NaCl–H2O phase diagram. Through analyzing the baking soda raw materials, the carbonation process, and the mother liquor, the company neutralized and recovered the mother liquor using lime. 14. Production of food-grade baking soda using heavy sodium carbonate solution: The carbonation effluent from the soda ash plant is sent to the mirabilite plant; after centrifugal separation and air drying, baking soda is produced. The mother liquor is then directed to the alkali chemical processing stage. 15. Comprehensively recycle the washing water from the soda ash calcination furnace and the chlor-alkali evaporation washing water to achieve one-step brine purification for caustic soda and soda ash production. 16. Automatic packaging and palletizing of soda ash: (Weifang) This project transforms the current semi-automatic packaging process for soda ash, enabling automatic bagging, sealing, metal detection, weight verification, and palletizing. It significantly reduces labor costs while enhancing both the technical level and management efficiency of soda ash packaging. 17. Program control of the four-in-one soda ash packaging system (dual-loop): It addresses the issue of each packaging line requiring its own storage area, which consumes a large amount of floor space, thereby saving on equipment and operating costs. 18. Tianjin Soda Plant uses bag filters to control dust: Starting in 1997, Tianjin Soda Plant employed PPC-type compartmentalized reverse-pulse bag filters in the ash conveying system of its lime kiln and for dust control in ash silos. It also utilized PPCA-type pulse jet bag collectors to address dust pollution caused by ammonium chloride during the processing of granular ammonium chloride, as well as dust pollution in the exhaust gases from ammonium chloride drying processes. Tests have shown that the dust removal efficiency exceeds 99.9%, and the dust concentration in the exhaust gas