APPLICATION OF BENTONITE IN OBTAINING SULFUR-CONTAINING UREA BASED ON A FLUSH OF UREA AND SULFUR

Abstract

This paper presents the results of a study of the processes for obtaining granular sulfur-containing carbamide from sulfur and a liquid carbamide melt using bentonite to influence the surface tension between two phases of sulfur and urea to obtain a mixed homogeneous phase. It was revealed that the addition of bentonite to sulfur before adding the latter to the melt of urea, which has a temperature of 135-145 °С at mass ratios (NH2)2CO : bentonite : sulfur = 100 : (1-7) : (1-15) prevents the stratification of melts sulfur and urea. The optimal conditions for obtaining, the composition and properties of granular sulfur-containing urea with a balanced content of nitrogen and sulfur are determined by adding a mixture of sulfur with bentonite to the urea melt before granulation. In fertilizers obtained with the addition of a mixture of sulfur with bentonite to the melt of carbamide at the studied ratios, the strength of the granules increases from the initial 2.65 to 4.76 MPa, the gyroscopic point increases from 58.4% to 62.3%, pH and porosity decrease from 8 02 to 5.32 and from 5.60 to 4.55, respectively, and the dissolution rate of the granules decreases 3.36 times. It was also found that when adding a mixture of sulfur with bentonite to the melt of carbamide, the density and viscosity of the melt increase with an increase in the amount of added mixture of sulfur with bentonite. An increase in the amount of addition of a mixture of sulfur and bentonite from 1 to 15 and from 1 to 7 g per 100 г melt of urea at a temperature of 135 °C leads to an increase in the density and viscosity of the melts from 1.16 to 1.33 g/cm3 and from 2.56 to 3.06 cPz. Microscopic examination showed that adding a mixture of sulfur with bentonite to the carbamide melt leads to a decrease in the size of micropores and microcracks up to 0.93 microns wide. On the basis of the results obtained, optimal technological parameters and a process flow diagram for the production of sulfur-containing granulated carbamide are proposed.