Study On Corrision Behavior Of Yellow Phosphorus Distillation Extraction From Phosphorus Sludge At Moderate High Temperature

Phosphorus sludge is one of the main by-products in the process of yellow phosphorus production,and it is phosphorus-containing hazardous substance and belongs to the hazardous waste in the phosphorus chemical industry.Once phosphorus sludge leakage occurs,it can cause very serious impact on surrounding environment and people.Phosphorus sludge is so corrosive that device corrosion speed is quite faster.So the whole system of distilling extraction yellow phosphorus can only be used for two years,which enables enterprise to increase production cost and cause heavy burden.There is much recyclable yellow phosphorus in phosphorus sludge,in order to obtain yellow phosphorus,our studying team has done a lot of design and reconstruction rearch on the device of yellow phosphorus extraction from phosphorus sludge at moderate high temperature,at the same time,obtained plentiful and substantial achievements greatly improving the recovery of phosphorus.But for the corrosion behavior in the process of yellow phosphorus extraction,we don't conduct research.So this article mainly studied the corrosion behavior in the process of yellow phosphorus distillation extraction from phosphorus sludge at moderate high temperature,preliminarily studied the corrosion reason and corrosion mechanism,put forward anti-corrosion measures,which provides the experiment and application basis for anti-corrosion technology development of yellow phosphorus distillation extraction from phosphorus sludge at moderate high temperature.In order to study the corrosion behavior in the process of yellow phosphorus distillation extraction from phosphorus sludge at moderate high temperature,it is necessary to design a set of reaction device,and use which to do yellow phosphorus extraction experiment and corrosion test,rearching the relationship between temperature and time in the process of yellow phosphorus extraction,reaction phenomenon and result.Then according to the weight method,the article studied the corrosion behavior of Q235 steel,45 steel and 304 stainless steel.The process of yellow phosphorus distillation extraction from phosphorus sludge at moderate high temperature is divided into two phases:water evaporation in phosphorus sludge(100?)and yellow phosphorus extraction(290?).This article mainly studied the corrosion behavior of Q235 steel,45 steel and 304 stainless steel in the two phases.The results show that the weight of three metal specimens decrease gradually in a straight line trend,the decreased weight and Corrosion rate of 45 steel are more than Q235 steel and 304 stainless steel,304 stainless steel is the least;Their corrosion kinetics curves are linear at 100?.At 290?,The weight change of three metal specimens show increased parabola trend and gradually level off,the increased weight and Corrosion rate of 45 steel are more than Q235 steel and 304 stainless steel,304 stainless steel is the least;Their corrosion kinetics curves are parabola.These techonologies scanning electron microscope,energy spectrum analysis and X-ray diffraction can be used for analysing corrosion pecimens morphology and element.At 100?,corrision product on the surface of 45 steel is mainly Fe(PO3)2;At 290?,it is mainly Fe(H2PO4)3.Corrision behavior of yellow phosphorus distillation extraction from phosphorus sludge at moderate high temperature begin from metal surface,and corrosive medium break metal surface membrane.At 100?,with rapid corrosion rate,there are iron phosphate generate on metal surface,but they fail to completely cover the metal surface to protect matrix and stop corrosion reaction,so metal corrode from outside to inside as well as weight decline.At 290?,because of the accumulation of corrosion products on the surface of samples gradually,the corrosion product film is compact on the surface of metal to isolate corrosion medium from metal matrix,which is protective and hinders corrosion.According to the weight method,the article studies on the relationship between weight increased(decreased)and time of Q235 steel,45 steel and 304 stainless steel with phosphorus sludge immersion at room temperature.As the growth of metal sample immersion time,the weight of Q235 steel and 45 steel first increase,then decrease,the weight decreased trend of 45 steel is greater than Q235 steel;and the weight changes of 304 stainless steel is more stable and less.Surface analysis of metal show that metal surface elements mainly are O,P and Fe,but it fail to accurately determine the products on the surface of metal sample.But we can know that the water in phosphorus sludge is acidic(pH = 5.5),in which occluded cell corrosion may occur.