| 摘要 |
FIELD: inorganic chemistry, chemical technology. SUBSTANCE: invention relates to method for preparing phosphorus-containing mineral fertilizer, namely, diammonium phosphate with stable dark color that is used with the broad market demand. Method involves mixing phosphoric acid with sulfuric acid, step-by-step neutralization of ammonia with a mixture of acids to the mole ratio NH3 : H3PO4 = 1.4 in the presence of coloring organic compounds and then to the value 1.75 followed by granulation, drying and the following purification of exhausting gases for two stages. Pulp of ammonia phosphates is fed to the first stage and a phosphoric acid-containing solution is fed to the second stage and prepared absorption liquids are returned to the process. Molasses that is a waste in sugar manufacturing as a syrup with viscosity index 4-8 Pa's taken in the amount 4-6 kg per 1 t of ready product are used as organic staining substances that are added to the absorption liquid obtained after the second absorption stage in the mole ratio NH3 : H3PO4 = 0.2-0.4 and the prepared mixture is returned to the first absorption stage. In realization of the method the uniformly colored product is prepared. EFFECT: improved preparing method, technological and ecological effectiveness of process. 3 ex |
