Method for continuously producing feed-grade urea phosphate from wet-method purified phosphoric acid strip liquor or washing residual liquid

Abstract

The invention discloses a method for continuously producing feed-grade urea phosphate from wet-method purified phosphoric acid strip liquor or washing residual liquid. The method comprises the following steps: firstly, adding the wet-method purified phosphoric acid strip liquor or washing residual liquid of which the concentration of P2O5 is 25-40% into a reaction tank, controlling the temperature to be 60-85 DEG C, stirring at a speed of 100-200r / min, keeping the temperature for 10-20 minutes, adding urea into the reaction tank in a mole ratio of phosphoric acid to urea of 1:(1.0-1.2), performing a stirring reaction for 60-90 minutes, and concentrating reaction liquid under a vacuum condition to increase the concentration of P2O5 to be 48-55%, so as to form a concentrated reactant material; reducing the temperature of the concentrated reactant material to be 5-40 DEG C, adding a crystal seed, and performing cooling constant-temperature crystallization under a stirring condition of 5-30r / min so as to separate urea phosphate; and performing centrifugal separation on the urea phosphate, and drying, thereby obtaining the feed-grade urea phosphate. The production cost is relatively low when being compared with that of industrial phosphoric acid or hot-method phosphoric acid, no activating agent, suspending agent and the like are needed in the production process, the process procedures are simple, and relatively high economic and environment-friendly values can be made.

Description

technical field [0001] The invention belongs to the field of phosphorus chemical industry, and in particular relates to a method for continuously producing urea phosphate by wet purification of phosphoric acid stripping liquid or raffinate. Background technique [0002] Urea phosphate, the chemical formula is CO(NH 2 ) 2 .H 3 PO 4 , N content is 17.7%, P 2 o 5 The content is 44.9%, and the aqueous solution is acidic. It is an important inorganic fine chemical product, which has a wide range of uses and prospects in both agriculture and industry, including silage preservatives, high-concentration nitrogen-phosphorus compound fertilizers, ammonium polyphosphate intermediates, flame retardants, and fire-proof cleaning Agents, etc., especially as feed additives for ruminants, can significantly improve the yield and quality of ruminant meat and milk. [0003] At present, domestic production of urea phosphate is mainly based on thermal phosphoric acid and wet phosphoric a...

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Problems solved by technology

The yield of thermal phosphoric acid is relatively high, but the cost is high and the production capacity is small; the production of urea phosphate by wet process phosphoric acid has been studied at home and abroad, but there are many impurities in wet process phosphoric acid, especially F - , SO 4 2- 、Al 3+ and Fe 3+ etc. have a greater impact on the yield and purity of urea phosphate products. The purity of urea phosphate products produced by non-purified wet-process phosphoric acid is not high. Generally, an activator needs to be added, and the circulation of the mother liquor is difficult. It is mostly used for the production of urea phosphate for fertilizers; If the urea phosphate is produced directly with 75% or 85% purified phosphoric acid, the cost is relatively high, and the general stripping solution needs to undergo multi-stage concentration, desulfurization, decolorization and other processes to produce 75% or 85% wet purified phosphoric acid, but for the production of urea phosphate The requirements for wet-process phosphoric acid are relatively low, and only the stripping solution can meet the requirements for F - , SO 4 2- 、Al 3+ and Fe 3+ and other impurities; in addition, 75% or 85% wet purification of phosphoric acid is used to produce urea phosphate, the crystallization and mother liquor mixture have a large solid-liquid ratio, poor fluidity, and difficult solid-liquid separation process

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