Corrosion of Different Materials in Combustion Chamber of Yellow Phosphorus Tail Gas in Industrial Boiler

About 75% of yellow phosphorus produced in the world is from China, and Yunnan province produces 60% of that in China. Yellow phosphorus is mostly produced by electric furnace from phosphate minerals. Through this method, 2500-3000 Nm/t tail gas is emitted, which causes pollution of the atmosphere. The key composition of the tail gas contains 80%~95%CO. Due to the “3R” principle (reducing, reusing, recycling), it is very important to reuse and recycle the tail gas. However, because of the complexity of composition, fluxion and corrosion behavior of the tail gas, little scientific research on the corrosion mechanism has been reported. Without the information, effective protective measures cannot be made. As a result, materials used in the boiler are prematurely aborted due to corrosion, and restricts the survival and sustainable development of the yellow phosphorus industry. Therefore, it is important to minimize corrosion caused by combustion of yellow phosphorus tail gas. In this paper, corrosion analysis of samples made from 6 different materials is reported to reveal the corrosion behavior under actual work conditions. After exposing to yellow phosphorus tail gas for 1,582 hours in the combustion chamber, the surface of each sample was corroded. The corrosion behavior is different for different materials: 1) Boiler steel and pearlitic heat-resisting steel: Phosphorus reacts with iron and iron phosphate is obtained. 2) Austenitic stainless steel: the sample surface was slightly corroded, but a lot of combustion products adhered. 3) Bainitic heat-resisting steel: the corrosion product was mainly iron oxide with a small quantity of sulfide. 4) Gray cast iron: graphite flake in the near surface region was eroded under high temperature and it resulted in exfoliation of the pearlite. Iron phosphate was also detected. Therefore, the corrosion happened at the same time as the combustion. 5) Particle reinforced Al-based composite material: the flaking off of SiC particles can accelerate corrosion. Interface between the SiC particles and the base material can induce corrosion. In summary, the design and application of surface coatings are necessary for the protection from corrosion in high temperature combustion chamber of yellow phosphorus tail gas in the boiler.