Известия Томского политехнического университета: Инжиниринг георесурсов (May 2019)
Study of potassium hydrogensulfate neutralization
Abstract
The relevance of the research is caused by the necessity to obtain the complex potassium sulfate fertilizers, which not contain chloride ion. The accumulation of chloride ion in soil leads to lower yields and increases the soil salinity level. The main aim of the work is to investigate potassium hydrogensulfate neutralization by ammonia in reactor with fluidized and fixed bed at different particle size; to establish the kinetic dependences of neutralization. The methods used in the study: theoretical analysis of processes, modeling of technological process in laboratory conditions, study of changes in the content of sulfuric acid in product in time by titration of product with sodium hydroxide, X-ray analysis of product, obtained by neutralization, finding of conversion degree of equation depending on time using the program «Table Curve 2D». The results. The authors have carried out the theoretical analysis of possible neutralizing ways and studied the hydrogen sulfate neutralization by ammonia gas in apparatus with fluidized and fixed bed. The equations of change in degree and rate of potassium hydrogensulfate neutralization by ammonia over time for particle sizes of potassium hydrogensulfate 0,3, 0,6 and 1,2 mm were obtained. The conclusions. It was ascertained that the most acceptable neutralizing agent is ammonia. The potassium hydrogensulfate should be neutralized by ammonia gas in apparatus with fluidized bed at linear gas velocity of 0,042 m/s. The end product of neutralization KHSO4 by ammonia gas in fluidized bed is the mixture of potassium and ammonium hydrogensulfate (КNH4H)2(SO4)3 and potassium hydrogen sulfate K5H3(SO4)4. It is not reasonable to use this substance as fertilizer, therefore, it requires additional neutralization by washing. The process is inhibited at neutralization in a fixed bed and residual sulfuric acid content in the product is higher than 8 %. The analysis of dependence of potassium hydrogensulfate neutralization degree on time in fluidized and fixed bed showed, that the neutralization degree increases, reaching a maximum at duration of 20 minutes, then it decreases gradually during the process in a fluidized bed, and it falls sharply during the neutralization in a fixed bed. The rate of chemical reactions in fluidized bed is determined by the size of reaction phase interface and it is limited by the formation and growth of reaction product nuclei, and limiting step in fixed bed is diffusion of ammonia molecules to the reaction zone.
