SU1174375A1 - Method of producing condensed phosphates - Google Patents

Abstract

A method for producing condensed phosphate from elemental phosphorus, including the interaction of the combustion products of phosphorus with alkali and alkaline earth metal salts or natural phosphates at elevated temperatures and molar ratio MeO: Pj Oj 1.0-1.2, followed by cooling the melt of reaction products, characterized by that, in order to increase the solubility of the product in mineral acids while simultaneously accelerating the process, the interaction of the products of combustion of phosphorus with alkali and alkaline earth metal salts during the This phosphate is carried out at 1050-1300 0, and cooling to 950-970С at a speed of 60100 deg / min, the melt at the specified temperature is held for 5-7 min, and then cooled at a speed of 250 (L 300 deg / min.

Description

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SP 1 The invention relates to the technology of obtaining co-condensed phosphates of alkaline and alkaline earth metals and can be used in the field of obtaining feed additives in animal husbandry. The purpose of the invention is to increase the solubility of the product in mineral acids while accelerating the process. Example. 10.65 kg of phosphorus per minute is fed to the cyclone nozzle for burning. Spraying and burning of phosphorus is carried out with compressed air which is supplied with an excess of against theoretical e 1.6, which is 93.3 kg / min. At the same time, the temperature in the reactor reaches 1156 ° C. Phosphorus anhydride containing products of phosphorus react with crushed chalk, which is fed into the cyclone in the amount of 20.82 kg / min, which corresponds to the CaO: P205 molar ratio of 1.2. The reaction products in the form of a calcium polyphosphate melt containing solid CaO inclusions flow from the cyclone into the collector at a rate of 35.2 kg / min. The melt collector chamber is made in the form of a straight angle box 1 m long, 0.5 m wide, and an outlet tap is placed in the end part opposite to the water nozzle at the level of the melt collector bottom. Cooling the melt to 950 ° С at a rate of 70 K / min ensures the supply of 2.14 kg / min of finely sprayed water to the collector. The total residence time of the melt in the collector is 9.0 minutes, while 6 minutes at 950 C. From the collection, a melt along a chute 0.5 m long is released into two rollers with a diameter of 0.15 m and a length of 0.4 m rotating in opposite directions. directions at 6 rpm. In the tube space of the rollers, 100 l of water per minute are given at a temperature of 20 ° C, which ensures the cooling of the product at a speed of 250 deg / min. Product plates with a thickness of 0.003-0.005 m are formed on the surface of the rollers. The product, cooled to 50-100 ° C, is sent to a hopper, from where a plate feeder is fed for grinding. Total process time 12 min. Contents 52, soluble in 0.4% HC1, 5A, 2%. Conducting the process at temperatures below 1050 ° C leads to a sharp slowdown due to the formation of a cake and a decrease in the quality of the product. The product obtained at a temperature below is a mixture of phosphates of high degrees of condensation and non-interacting solid grain and is highly hygroscopic and caking. Conducting the process at temperatures above is impractical due to the temperature range in which the more stable molecular form is pyrophosphate. An increase in the content of the latter leads to a decrease in the ability of the product to dissolve in water and solutions of mineral acids. The molar ratio MeO: P205 to be provided in the reaction apparatus and in the target product is 1.0-1.2. Maintaining the main process of interaction with a molar ratio of MeOtPjOj 1 is impractical due to an increase in the content of highly condensed phosphates in the product and, therefore, an increase in hygroscopicity and caking of the target product. In addition, with a molar ratio of MeOtP Of 1, there is an increase in the concentration in the exhaust gases and the volume of the latter, which leads to an increase in the dimensions of the reactor and the next after p, the gas cleaning equipment. The supply to the reactor of an equivalent or more equivalent amount of phosphorus for the metaform also leads to a low utilization of the thermophysical properties of yellow phosphorus due to the need to remove heat from the reactor when it is burned. Conducting the main process of interaction with the supply of MeO in the reactor in an amount greater than necessary to ensure a molar ratio of MeOtPjOj- 1.2 leads to an increase in the melt viscosity and impedes its transport, a decrease in the total velocity g

crystalline, poorly soluble in water and solutions of mineral acids products.

The need for rapid cooling of the melt to 950–970s and its aging for 5–7 min is due to the creation of favorable conditions for melting the crystalline phase in the form of tremelite from the melt, the presence of which determines the quality of the final product.

The duration of the melt melting of less than 5 minutes leads to a decrease in the quality of the product due to lack of time required for the formation of tremelite. An increase in the melting time of the melt over 7 min leads to an increase in the melt viscosity due to homogenization, i.e. completion of the reaction of the crystalline phase with the melt of the polyphosphate, which is accompanied by an increase in the s melt content of the pyro form of phosphate. This leads to a low rate of dissolution and hydrolysis of the product in solution.

Cooling the melt to EZO-ETO C at a rate of more than 100 K / min makes it necessary to increase the melt recovery time at a given temperature, melt viscosity due to the completion of the polyphosphate melt in the reaction, which is accompanied by an increase in the pyroform of phosphate in the melt. This results in a low rate of dissolution and hydrolysis of the product in solution. Cooling the melt at a rate of less than 60 K / min leads to a decrease in the quality of the product due to the completion of the reaction between the crystallized phase and the melt and the formation of poorly soluble pyrophosphates in the system.

Further cooling of the melt at a rate of less than 250 deg / min leads to the formation of a hardly soluble crystalline / i Ca (PO3) 1.

743754

The cooling rate of the melt, I exceeding 300 K / min, necessitates the use of water as a coolant, which, as a result of direct contact with the product, leads to the formation of a sticky film of coacervate on its surface, which complicates the subsequent process of grinding the polyphosphate during 10 production of polyphosphate flour.

According to a known method, the duration of the process is h, the solubility of the product is 3-5%.

15 The feasibility of the selected process temperature intervals is illustrated in Table. one.

Conditions of experience: MeO: P, 0. 1.1:, 1.0; cooling rate of the product to 20–70 deg / min; melt hardening time at 4 min; further cooling of the product at a speed of 270 degrees / min.

The effect of melt cooling conditions to 950-970 ° C is illustrated in Table. 2..

Conditions of the experiment: The molar ratio of the reagents MeO: P205 is 1.1: 1.0; process temperature is 1150 ° C, time 30 for the melt is at 6 minutes, cooling rate of the product is 270 degrees / ffflH.

In tab. Figure 3 presents the results, the explanation of the effect of time on holding the melt in the temperature range 950-970 C.

Catch the process: molar ratio of reagents Me0: p2p 1.1: 1.0; process temperature, cooling of the alloy to the cooling rate, 70 deg / min; the rate of further cooling is 270 degrees / mi. In tab. Figure 4 presents the results explaining the effect of the rate 5 on further cooling the product.

Process conditions: molar ratio MeO: P O I 1.1: 1.0j process temperature melt cooling to, further cooling rate 70 degrees / min; melt holding time at 960 ° C 6 min. Tempe Indicators -----. 1000 I Melt viscosity, P Process time, min Formation of a speck, content soluble in 0.4% HC1,% e-5 Melt cooling rate to, deg / deg50 60 PjO .. content, soluble in 0.4% HC1 solution,% 39.1 57.2 Melt ejection time at 960C, min3 Table 1 process profile, С --ig-1 1050 1150 1300 1350 18.0 12.0 4.0-5.0 3.0 10.0 13.0 14.0 57.3 53.3 36.8 T a b l and c a 2 70 80 100 110. 54.2 53.9 52.8 41.2 T a b l and c a 3 5679

Content soluble in 0.4% solution 41.4 56.9 solution, NS 1,% 54.2 53.6 40.2

42.3 54.0

Table 4

54.2

55,6

55,8

Claims (1)

METHOD FOR PRODUCING CONDENSED PHOSPHATES from elemental phosphorus, including the interaction of products of the combustion of phosphorus with salts of alkali and alkaline earth metals or natural phosphates at an elevated temperature and a molar ratio of MeO: P ₂ Oy = 1.0-1.2, followed by cooling the melt of reaction products, characterized in that, in order to increase the solubility of the product in mineral acids while accelerating the process *, the interaction of products of the combustion of phosphorus with salts of alkali and alkaline earth metals with natural phosphate is carried out at about 1050-1300 ^ 0, and cooled to 950-970 ° C at a rate of 60100 K / min, the melt at said temperature vderzhivayut 5-7 min and § then cooled at 250300 ° C / min. 1174375 2 P ₂ 0y, soluble in 0.4% HC1, 54.2%.