As of early June 2023, the first domestic acidic high-salt wastewater resource-based treatment project of Zenith Steel Group (Nantong) Co., Ltd., which was constructed under the general contracting of CIE, has been operating stably for more than half a year since it was put into operation in October 2022, and all recovered anhydrous calcium chloride has recently been sold at a high price.

The multi-pollutant flue gas purification technology with activated carbon can achieve efficient and collaborative in-depth treatment of multiple pollutants and resource-based utilization of sulfur dioxide. However, acidic high-salt wastewater will be produced during the resource-based utilization of sulfur dioxide, which has high salinity and complex pollutants. Conventional treatment technology has problems such as high energy consumption, high investment cost and low quality of by-product salt, which are technical bottlenecks and difficulties to be solved urgently for water pollution prevention and control in the steel industry.

Based on the high content of chloride ions and calcium ions in acidic high-salt wastewater, CIE has independently developed a technology for spray drying and recovery of calcium chloride in acidic high-salt wastewater. Through multi-stage pretreatment of "calcium sulfate induced precipitation-strong oxidation of organic matters-heavy metal chelating and capture", coupled with the spray drying and calcium chloride recovery process system, it has realized efficient selective removal of sulfate ions and deep purification of heavy metal ions in high-chlorine environment, and high purity anhydrous calcium chloride can be recovered.

Since the project was put into operation, the equipment has operated stably and achieved good results, which can realize zero discharge of wastewater. At the same time, it can produce nearly 1,000 tons of anhydrous calcium chloride with purity >95% annually (meeting the requirements of GB/T 26520-2021 Type I Anhydrous Calcium Chloride), and the sales value of anhydrous calcium chloride is 6 to 10 times that of conventional sodium chloride salt, showing good economic benefits.