The stainless steels used in the soda ash industry are mainly austenitic stainless steels and austenitic-ferritic duplex stainless steels. Among them, 00Mo5(00Cr18Ni18Mo5) stainless steel, high nickel molybdenum 904L (00Cr20Ni25Mo4) stainless steel and 316L (00Cr18Ni12Mo2) stainless steel containing molybdenum in austenitic stainless steel are the most widely used. The duplex stainless steel mainly has austenite-ferrite duplex stainless steel 3RE60 (00Cr18Ni8Mo3Si2) and CD4Mcu cast stainless steel these two materials.
00Mo5 stainless steel is mainly used as a cooling tube of carbonization tower in soda ash. It has excellent pitting corrosion resistance and crevice corrosion resistance, and can even be used for cooling small pipes contacting seawater medium. However, this material is not a standard stainless steel series. It is difficult to purchase in the market, and its use is limited to a certain extent, and it has not been widely promoted.
904L not only has high chromium-nickel content, but also has a high Mo content, and has better corrosion resistance than 00Mo5 stainless steel. In soda ash production, 904L exhibits better resistance to general corrosion and pitting resistance. In addition, 904 L has good hot and cold workability. In Europe, 904L is considered to have excellent corrosion resistance comparable to that of titanium in soda ash equipment. It is used in many titanium-depleted countries to replace titanium in soda ash applications. It can be used not only as a shell material for the pressure vessel, but also as a forging and casting for the tubesheet and pump of the heat exchanger.
In addition, 316L, 304 and other stainless steel are also widely used in soda ash equipment, pipes, instruments and valves.
In the production of caustic soda multi-effect evaporation which is closely related to the production of soda ash, the pump valve made of 0Cr18Ni9Ti stainless steel with high concentration of NaOH content of 45%, NaCl content of 20% and temperature of 150 °C (boiling) is less than 1 In the month, the pipe made of 1Cr18Ni9Ti has a service life of only 11 months. The ultra-pure ferritic stainless steel (000Cr26Mo1) on the evaporator of the concentrated alkali (42%-46%) production line has a wall corrosion rate of only 0.018 mm/a and a service life of more than 10 years.