Research On The Main Influencing Factors And Optimization Of Ammonium Sulfate Crystallization By-product Of Sintering Flue Gas Ammonia Desulfurization

Ammonium sulfate is one of the important chemical by-products,which is widely used in protein purification,agriculture and other industries.However,in the industrial production of ammonium sulfate,there are problems such as small crystal size,uneven particle size distribution,and poor quality of crystal products,making it difficult to increase the revenue of ammonium sulfate.Take the 300m² sintering machine flue gas,ammonia,method,and desulfurization system in Kunming Iron and Steel New District as an example,the ammonium sulfate crystallization process has crystallization effects.There are many factors,low crystallization rate,unstable nucleation,and poor quality of ammonium sulfate.In order to solve the above problems,this paper studies the main factors affecting the crystallization of ammonium sulfate based on the thermodynamic data of ammonium sulfate crystallization,and determines the optimization of the ammonium sulfate crystallization process in ammonia desulfurization based on the experimental results.The operating conditions are obtained.The main conclusions are as follows:1.In this paper,the solubility of ammonium sulfate and the crystal metastable zone in different solvents were studied by dynamic laser method.The change in width.The results show that ammonium sulfate is easily soluble in water,and its solubility increases with the increase of temperature,and the width of the metastable zone decreases.When the pH value of the solvent decreases,the solubility decreases and the width of the metastable zone increases.With the increase of the concentration of Fe³⁺in the solvent,the solubility also decreases,and the width of the metastable zone becomes stable after the rapid increase of the concentration.With the increase of the stirring rate,the width of the metastable zone decreases.2.Using Matlab software and Apelblat empirical equation to correlate the relationship between the solubility of ammonium sulfate and temperature,and based on the Vanter Hoff equation and Apelblat empirical equation,calculate the dissolution enthalpy,dissolution entropy and molar Gibb of ammonium sulfate Free energy.The results show that the model calculated value obtained by the Apelblat empirical equation has a small deviation from the experimental value.This equation is suitable for the ammonium sulfate solubility experiment and has a good fitting effect;the thermodynamic calculation data shows that it is within the scope of the experimental conditions.The dissolution process of ammonium sulfate in different solvents is endothermic and non-spontaneous.3.The influence of mother liquor pH,Fe³⁺concentration and stirring rate on the cooling crystallization process of ammonium sulfate was investigated,and the influence of various factors on the crystal crystallization amount,average particle size and distribution,crystal shape and crystallinity was studied,and the influence was comprehensively considered.As a result,the optimal experimental level range for each investigation factor was finally determined.The mother liquor pH was 3.5,4.5and 5.5,Fe³⁺was 0.1 g·L^-1,0.3 g·L^-1and 0.5 g·L^-1,and the stirring rate was 150r·min^-1,200 r·min^-1and 250 r·min^-1.4.In order to obtain better crystal quality and suitable particle size distribution,optimize the ammonium sulfate crystallization process.On the basis of determining the optimal experimental level range of each investigating factor,taking the average crystal size and C.V.as the response value,mother liquor pH(A),stirring rate(B)and Fe³⁺concentration(C)as the investigating factors,the Design is adopted.Expect software carried out the response surface research,and then obtained the optimal process parameters.The experimental results show that the quadratic regression model on the average particle size and the 2FI regression model on the C.V.established by the response surface experimental design have good fitting effects and reliability;when the pH of the mother liquor is 5.5 and the stirring rate is 150r·min^-1.When the concentration of and Fe³⁺is 0.3 g·L^-1,the theoretical average particle size and C.V.value that can be obtained are 0.985mm and 793.719,respectively.The experimental verification shows that the theoretical value and the experimental value have a small error,the regression model fits well and the parameters are reliable.Through the study on the thermodynamic properties and crystallization influencing factors of ammonium sulfate,the optimal process parameters were finally obtained,which could provide solutions to the problems existing in the production of ammonium sulfate in ammonia desulfurization in the new area of Kunming Iron and Steel Co.,Ltd.and provide reference for the optimization of crystallization process parameters.