CS214520B1 - A method of producing urea or ammonium phosphate feed phosphate - Google Patents

Abstract

The method of producing feed urea phosphate or ammonium phosphate from impure (extracted) phosphoric acid is based on dewatering the reaction solution and extracting soluble impurities from the surface and core of the particles with a saturated aqueous solution of urea phosphate or ammonium phosphate. The purified product is then dried and shipped. The extractant is then processed into NP or NEK fertilizer.

Description

The invention relates to a process for the production of feed urea phosphate or ammonium phosphate prepared from impure (extractive) phosphoric acid.

Process for preparing urea or ammonium phosphate from extraction acid. Phosphoric direct drying of aqueous solutions of these salts and subsequent extraction with saturated solutions of these salts, as described herein, is not described in the literature. Urea phosphate purification technologies are described for example: two-stage crystallization of urea phosphate according to the TVA procedure, which utilizes the reoyl of the mother liquors dosed after separation of the crystalline phase by centrifugation into the first crystallizer where the phosphoric acid extraction extract (54% ^ 2 ^ 5 ^ ^and P) ^evn ® urea (see TVA 12 ^ Demonstration Ootober 18-19, 1978 - New Development in Fertilizer Technology, TVAMuscle Schoals, Alabama USA). and Urea, Paper Present at ACS Meeting 1975).

Urea phosphate or ammonium phosphate is prepared by reacting phosphoric acid extractive with urea or ammonia in an aqueous solution. The resulting urea phosphate or ammonium phosphate solution is either spray dried to a spray dryer or is not dewatered in a tumble dryer while crystallizing the product. In both processes, impurities from the phosphoric acid extract, which were dissolved in the phosphoric acid and the phosphoric acid, are located on the surface of the crystals. after reaction with urea they became soluble. The urea phosphate or ammonium phosphate thus obtained is extracted in one step or in a multi-stage, countercurrent saturated aqueous solution of these phosphates. In the first contacting step, steam condensate or pure water is used, which dissolves fine particles of phosphoronate and other soluble impurities as well as fine particles of urea or ammonium phosphate from the surface of the particles, thereby saturating the extraction solution, which is 1: 1 to 1 5. In the next extraction steps, the extractant (saturated aqueous urea or ammonium phosphate solution) is saturated with impurities, such as urea complexes of iron salts, also with phosphorus, fluoride and arsenic salts, in the last step (in contact with hot or cold crystals) with an extractor), the crystals are firstly humidified.

If there are organic phosphoric acid residues present, they are separately extracted prior to the actual extraction with an organic extract, which does not dissolve urea or ammonium phosphate, but only organic impurities and is very volatile. A saturated solution which served as an extractant after separation from the crystals, respectively. The particles in the final extraction step can be further processed through silica or other compounds thereof, whereupon the fluorine is converted to fluorosilicates, the equimolar ratio of phosphoric acid to urea or ammonia is adjusted and dried again. The dried crystals may be treated to NP or NKP fertilizer, or by dissolving urea or ammonium phosphate in water to return the extraction solution. The insoluble fluoro compounds are separated as a sediment or filter cake and subjected to further treatment.

In the first extraction step, a product is obtained which is of a quality corresponding to feed urea phosphate or ammonium phosphate. This is packed and shipped after drying under 0.5 wt.

The present invention makes it possible to use phosphoric acid extracted for the preparation of feed urea phosphate or ammonium phosphate with a high degree of efficiency for utilizing the phosphorus component. Such processing of phosphoric acid to urea phosphate is technologically simple, economical, and allows the preparation of a finished product in one stream, with high raw material efficiency.

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Examples:

Example 1 "

Extractive phosphoric acid in an amount of 14.7 kg / ha containing 50% by weight of PgO4, 3% by weight of tri-monobasic acid Pe and Al, 0.5% by weight of P and 0.0017% by weight of As is reacted with 10.9 kg / h '55 % by weight aqueous urea solution. The resulting urea phosphate solution is dried at 120 ° C in a spray drier to a water content of 0.5% by weight. 16.5 kg / h of product are obtained. The warm product in the eight-stage extractor is countercurrently extracted with a saturated (aqueous) solution of urea phosphate, which is formed by mixing 1 part by weight of water in the first stage of the extractor with 3 parts by weight of solid product at 20 ° C. The saturated solution (extra-solvent) contains 50 wt% urea phosphate and the purified crystalline urea phosphate is free of Pe and Al oxides. The P 'content decreased to 0.001 wt% and the As decreased to 0.0008 wt%. From the first stage of the extractor, after separation of the saturated solution, 11.0 kg / h of feed urea phosphate containing about 3% by weight of water are obtained. After drying, 10.6 kg / h of product with a minimum content of 17% by weight are obtained. % N and 44 wt. Pg0.880 represents 66% efficacy on raw material convenience. The product is crystalline, white, odorless and thermo-stable up to 60 ° C. The extender after the last extraction stage is neutralized and dried, yielding about 6 kg / h of NP fertilizer.

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Example 2: Extraction phosphoric acid in an amount of 0.147 kg and a 50% w Ρ ^ ₂ 0, 3% by weight of trivalent metal oxides, 0.5% by weight P "and 0.0017%, and, with the addition of 0.028 kg of water is treated with ammonia in an amount of 0,013 kg. A solution is obtained with a water content of 45.5%. After drying, 0.089 kg of product is obtained, which is extracted with a saturated aqueous solution of ammonium phosphate in a solution by weight ratio. product - 1: 5. After separation of the solution, 0.0885 kg of wet product containing about 3% by weight of water is obtained. 0.02 kg of this is dissolved in a saturated solution and reused as an extract. The wet product is then dried to give 0.0665 kg of purified ammonium phosphate containing 12.2 wt. N and 61.2 wt. P ₂ O, without P "and oxides, and the As content dropped to 0.0008 wt%. The product is crystalline, white and odorless. The extender is dried after the process, made neutralized and added to the NPK fertilizer.

Claims (1)

The means by the production of feed phosphate, urea or ammonium phosphate by treatment of the extraction of phosphoric acid with urea _or ammonia, washing and then drying the prmné purposes, characterized in that the dried urea phosphate, or ammonium phosphate was extracted with saturated uvedenýoh fosforeonanov in a mutual weight ratio of solution: product - 1 s 3 and at ⁶ to 20 C, the mother liquor was spraciuje the BS respectively, NPK fertilizers and pure urea phosphate and ammonium was again dried at 140 ° C and is adjusted.