Those who know about the salt removal device, please come in

Me too; we’re really worried about the desulfurization waste liquid at our factory right now

The desulfurization liquid is sent to the decolorization tank where activated carbon is used for decolorization; thereafter, it is filtered through a pressure filter. The clear liquid obtained is then sent to a concentration tank for vacuum concentration, followed by another filtration step using a pressure filter. Here, the thio-product is obtained; the clear liquid is then subjected to a second concentration step. After concentration, it is fed into a filter press for filtration, and the resulting clear liquid is sent to a crystallization tank for crystallization. The mother liquor from crystallization is centrifuged, and this centrifugated mother liquor is returned for further concentration. Except for crystallization, which takes place at atmospheric pressure, the entire above process is carried out under negative pressure.

The desulfurization liquid is pumped into the salt-removal high-level tank, from where it is sent to the concentration vessel via a pump. A vacuum pump and steam are then used to carry out vacuum distillation; when the temperature reaches 140 degrees, the double salt in the concentration vessel is transferred to a water-cooled sheeting machine

The stepwise crystallization method is only suitable for ammonia-based desulfurization and the purification of ammonium thiocyanate, and it is difficult to achieve continuous production with a purity of over 98%. I mainly engage in alkaline desulfurization to purify sodium thiocyanate, and the market for this product is very good.

The first step involves thermal decomposition, decolorization, and impurity removal: the solution is heated to 80–85°C under reduced pressure, where the polysulfides decompose into elemental sulfur, ammonia, and hydrogen sulfide; thiosulfate converts to sulfate. Activated carbon is used to adsorb the precipitated substances, causing the solution to change from alkaline to acidic and its color to change from dark green to colorless. After completing the first step, activated carbon and impurities are separated by filtration, and the clear liquid proceeds to the second step, where the solution is concentrated through vacuum evaporation. Under conditions of a vacuum pressure of 0.09 MPa and a temperature of 80–90°C, some of the water is removed, thereby increasing the salt concentration. Then thermal filtration is carried out to remove impurities. The filtrate containing anhydrous sulfuric acid crystals, etc., is placed in a crystallization tank and cooled to around 40 °C, whereupon anhydrous thiosulfuric acid crystals precipitate; these are then hot-filtered at a constant temperature. The filtrate after the separation of thiosulfate an was concentrated by vacuum evaporation a second time. Vacuum evaporation is carried out under the same temperature and vacuum conditions to remove some of the water, thereby further increasing the concentration of ammonium thiocyanate. Proceed to the second step of processing. The concentrate is then hot-filtered through a vacuum filter to remove pyrolysis impurities. The filtrate is placed in a crystallization tank and cooled to around 25°C; seeds are then added to initiate crystallization. The crystals appear flaky. After the operation of the crystallization tank is completed, the crystals together with the mother liquor are placed in a centrifuge. During centrifugation, steam condensate is sprayed onto the surface of the crystals to wash them and remove impurities, thereby ensuring that the quality of the crystals meets the specified standards. The filtrate is recycled back to the feed solution to improve the extraction efficiency of the product. The process equipment includes: decolorization of the original waste liquid ； One vacuum evaporation concentration step, followed by cooling for crystallization and filtration to obtain crude thiosulfurous acid ； Three processes of heating and evaporation concentration: secondary vacuum evaporation concentration, cooling crystallization, water washing, filtration, and extraction of ammonium thiocyanate. The crude product is recrystallized to obtain a qualified product; in addition, a vacuum pump system is also included. The characteristics of this process method are: the use of activated carbon for decolorization, and preheating to decompose polysulfides and remove elemental sulfur. Concentration is achieved through vacuum evaporation; the product is then purified by cooling, crystallization, and washing with crystallization water. The vapor condensate from vacuum evaporation is condensed ammonia, which is returned to the process system. Waste activated carbon can be regenerated through hot air oxidation, and it can generally be reused 2 to 3 times.

I work at Jiangsu Kangmao Environmental Protection Engineering Co., Ltd., where we specialize in the design, installation, commissioning, and operation of salt extraction processes. Those who are interested can contact Ji Guobiao at 18652580276

Shenhua Xilai Feng, Wuhai Guangna, and Xuzhou Weitian; the latter two are already in normal operation