Fundamental Research On Negative Pressure Desorption Process Of SO₂－rich Citrate Solution

With Silver Copper Corporation method using copper-enriched bath treatmentprocess maturity Kazakhstan concentrates containing rhenium, sodium thiosulfatesulfide precipitation recycled flue gas purification of waste acid wash rhenium projectimplemented. Copper thiosulfate pentahydrate in need of about1,500tons, and thencontinued the flash process completed and processing of copper concentratescontaining rhenium, rhenium sulfide precipitation for sodium thiosulfate pentahydratewill reach3000t/a.. Adopt a system of acid fumes as raw materials for the productionof sodium thiosulfate method using multi-generation process, may lead to lowerproduction costs and achieve a variety of sulfur production purposes.Citrate absorption-desorption desulfurization technology is one of the mostpractical and promising FGD techniques with such advantages as high usage rate ofsulfur resources, large capacity of absorption, stable absorbent and so on. Traditionalcitrate method has some flaws on its formula of absorbing liquid and desorptionmethod. This will lead to a higher desorption energy barrier and serious cycle catalytic reaction and finally cause low desorption efficiency of rich absorbing liquid, highdesorption energy consumption and difficult cycle of absorbing liquid. Therefore, itwould be helpful to enhance the absorption and desorption efficiency, decrease allkinds of side reactions and desorption energy consumption as well as solve theproblems in the current technique by improving the absorbent formula and exploringnew desorption method.In this paper, the author will calculate the citrate absorbent’s absorption capacity,do experiments on new type of citrate absorption capacity, gas-liquid equilibrium invacuum environment and study the sulfuric acid root of low temperature crystallizationpurification desorption barren solution as well as the balance relationship betweenbuffer capacity and gas-liquid of Multivariate multicomponent buffer solution underthe vacuum environment. This paper will also investigate the relationships among allkinds of compositions, density, desorption temperature and pressure in the desorptionrich liquid during the vacuum desorption process as well as the equilibrium partialpressure relationship between sulfur dioxide and water in the gas doping.What’s more,it will analyze the effects of solution properties and composition in the freezing processon purification.The experimental result shows that new type of citrate method has a highabsorption capacity of sulfur dioxide which will change a lot as the absorbingtemperature, citrate density and the initial solution pH change; the reduced pressuredesorption can improve the efficiency of the rich absorbing liquid and reduceside-effects of absorbent to its lowest level, which will guarantee high absorbingcapacity and solution stability of regeneration absorbing liquid after severalcirculations; low temperature crystallization can make deprivation and purification ofsulfuric acid root in the desorption of barren solution possible, which will ensure thesmallest sulfur side reaction during the cyclic absorption process. Considering theoverall efficiency and cost of the three-stage-process of absorption desorption andpurification, the main technological parameters in the experiment is determined asfollows: the original absorbing liquid pH4.5, total concentration of citric acid root1.5mol/L,40℃absorption temperature,100℃desorption temperature,0.8atm pressure and3℃freezing temperature.