SU806659A1 - Method of producting complex fertilizer - Google Patents

Description

one

The invention relates to a technique for producing complex fertilizer. Nitric acid processing of natural phosphates.

A method is known for producing complex concentrated fertilizers by decomposing phosphate with nitric acid and a circulating mixture of ammonium nitrate in phosphoric acid, followed by precipitation of calcium ions from a solution of sulfuric acid and sulmonium sulfate, separating phosphogypsum and processing the filtrate into the finished product by ammoniation, mixing it with potassium salt and drying I. .

The disadvantage of this method is the low content of the water-soluble form of phosphoric anhydride in the fertilizer during the processing of substandard (containing large amounts of impurities) phosphates, due to the conversion of impurities contained in the raw materials into nitrogen. acid stretching, which is predetermined by the duration of the contact of the raw material with the acid and is associated with the sequential implementation of a number of stages of the technological process (phosphate dissolution and crystallization of the solid phase — calcium sulfate).

The closest to the proposed technical essence and the achieved result is a method of obtaining a complex fertilizer by decomposing a phosphate raw material with nitric acid, followed by separating calcium from sulfuric acid and processing the obtained filtrate into complex fertilizers.

When this method is used to process substandard phosphates with a high content of impurities (one-and-a-half oxides and magnesium compounds), the latter transfer to the liquid phase to a greater extent than the longer time. component interactions. Despite the p & supply of natural phosphate (25-75% in the first stage and 75-25% in the second), it is in contact with the acidic solution, both in the decomposition stage and in the precipitation stage of calcium sulfate. Therefore, the soluble part of the minerals of impurities has time to practically go completely into the liquid phase 2.

Claims (2)

The disadvantage of the method is a high degree of impurity transition into the liquid phase during the processing of substandard raw materials, which leads to a decrease in the content of water-soluble phosphates in the fertilizer. The purpose of the invention is to increase the content in the water-soluble form in the fertilizer during the processing of substandard phosphates. The goal is achieved by the fact that in the known method, which consists in decomposing phosphate raw material with nitric acid, followed by separating calcium with sulfuric acid and processing the resulting filtrate into complex fertilizers, first decomposing 40-60% of phosphate raw material with nitric acid for 20-30 minutes, followed by by adding sulfuric acid in an amount to ensure the precipitation of all the calcium ions contained in it from the solution, the remaining 60-40% phosphate raw material is introduced and the precipitate containing insoluble materials is separated. Eames. Such a design of the process makes it possible to reduce the contact time of an acidic solution with minerals containing impurities by a factor of 2-3, while the phosphate part of the raw material is practically completely extracted into the liquid phase. After separation of the impurity sediment together with sulphate crystals. Calcium from the filtrate precipitates calcium ions introduced into the system from the second portion of the phosphate raw material. The second stage of calcium sulfate crystallization is carried out in a solution that does not contain impurity minerals, and, therefore, is not accompanied by their transition into a production solution. Example 1. In the quality of raw materials used washed, calcined at, concentrate-Egorye place mass. %: -PaOg 23.8 births, 0.8; MgO CaO 37.8; ,, 8,0; A1, .0a 2.08; but. 20.8; F 2.3. 40 kg of phosphorite decompose 76.6 kg of 50% nitric acid within 20 minutes. To the resulting pulp add 46.2 kg of 93%. 100 kg of washing water and 300 kg of circulating solution for binding part of calcium ions in the form of calcium sulfate and conversion of calcium nitrate. The remaining portion of natural phosphate, yfeO KG, is added to 562.8k of the obtained pulp ;. The insoluble residue and undisturbed impurity minerals are filtered off with 90 kg of gypsum crystals by filtration and washed with 70 kg of water. Removal of the dry washed precipitate is 1000 kg / MQ. Wash water is leveled at the stage of precipitation of calcium ions with sulfuric acid. The filtrate in the amount of 532.8 kg is treated with 107.2 kg of a 40% aglmonium sulfate solution to extract the residual calcium. The pulp in the amount of 640 kg is filtered with the separation of 55 kg of pure phosphogypsum, washed with 30 kg of water, suitable for conversion to ammonium sulfate. The washes in the amount of 30 kg are combined with the washings from the filtration of the phosphogypsum mud and sent to the stage of precipitation of calcium ions with sulfuric acid. The filtrate in the amount of 585 kg is divided by two. stream, 300 kg is used as a working solution, and 285 kg are ammoniated to a pH of .4.5, mixed with 38 kg of KC 1 (60%) and evaporated to remove .196 kg of H / jiO. 143 kg of 143 kg of nitroammofoski brand 16:16:16 contain 90% of P / iO, - in water-soluble form, against 80-85% by a known method. Example 2. 50 kg of phosphorite decompose 76.6 kg of 50% nitric acid for 25 minutes in the presence of 300 kg of working solution. To the resulting pulp, 46.2 kg of 93% and 100 kg of wash water are added. To the 572.8 kg of the obtained pulp is added the remaining 1 part of the natural phosphate (50 kg. The precipitate in the amount of 90 kg is separated by filtration and washed with 70 kg of water. Removal of dry OTG / 1TH SEDEME is 1500 kg / m-h. Wash water used analogously to example 1. The filtrate in the amount of 532.8 kg is processed into a complex fertilizer —nitroammofosk analogously to example 1. The obtained fertilizer contains 95% P. in water-soluble form. ”Example 3. 60 kg of phosphate decompose 76.6 kg of 50% nitrogen acid for 30 min in the presence of 300 kg of the working solution. 46.2 kg of 93% H.SO2 and 100 kg of wash water are added to the pulp. The remaining portion of natural phosphate 40 kg is added to 582.8 kg of the obtained pulp. The same amount of precipitate as in Example 1 is separated by filtration, ( The dry washed sediment is 1200 kg / m-h. The filtrate is processed into a complex fertilizer - nitroammophoshka, as in Example 1. The resulting fertilizer contains 94% in water-soluble form. Formula of the invention The method of obtaining complex fertilizer by decomposing phosphate raw materials with nitric acid followed by separation calcium sulfuric acid and processing the resulting filtrate into complex fertilizers, characterized in that, in order to increase the content of XRD in water-soluble form during the processing of non-conventional phosphates, 40-60% of the phosphate raw material is decomposed with nitric acid for 20-30 minutes, followed by the addition of sulfuric acids in an amount to precipitate the precipitated calcium ions by introducing the 5 remaining 60-40% phosphate raw material and separating the precipitate. Information sources, . taken into account during the examination 1. Abstracts of the IXth All-Union 8066596 Scientific and Technical Conference on the Technology of Inorganic Substances and Mineral Fertilizers, May 1974. Perm, 1974, part 1, pp.34-35. 2. Patent of Great Britain No. 115376, cl. C 1 A, 1969 (prototype).