SU1654293A1 - Method for obtaining microelement-containing carbamide - Google Patents

Abstract

The invention relates to the field of chemistry, in particular to chemical technology of mineral fertilizers containing trace elements. The purpose of the invention is to increase the strength and decrease the dissolution rate of the granules while reducing the decomposition of urea. The essence of the method is the introduction of ammonium sulphate solutions of trace elements into the technological cycle of urea production after the first step of evaporation. Salts of sulfates of microelements are preliminarily dissolved in an aqueous solution of ammonia with a ratio of Me: NH3. equal to 1: (6-10), to obtain water-ammonia sulphate solutions of trace elements, sarraschaschih, wt.% Me (2-25, (NKUfcSCM 2-15, 2-10, water - the rest, where Me is copper, zinc cobalt, nickel 2 Cp f-crystals, 4 tab.

Description

SP G

This invention relates to chemistry, in particular chemical technology of mineral fertilizers containing trace elements.

The purpose of the invention is to increase the strength and decrease the rate of dissolution of the granules while reducing the decomposition of urea.

Example 1. 0.8 g of cobalt sulfate is dissolved in 10 g of 13% MHdOH to give a solution containing, in wt.%. Co (NH3) 4XOH} 22.3; (NH4) 2S04 1.9; NH4OH2; water 13.8, which is introduced in 104 g of a 95% urea melt; The mixture is evaporated and granulated to obtain 100 g of fertilizer of the composition,%: Co (NH2) 2 99; Co (NH3MOH) 2 0.5% or in terms of the element 0.2% Co (NH / j) 2S040.4, H200.25,

Example 2. 30 g of zinc sulphate dihydrate are dissolved in 70 g of a 25% solution of MH-YN. Get a solution containing, wt.%: Zn (NH3) 4XOH) 2 25; (19.7:

MH40H2, water 53.3, 48 g of which is introduced 84 g of 95% urea melt. The mixture is evaporated and granulated to give 100 g of fertilizer of the composition,%: Co (MH3) 2 79.5; 7п (МНз) 4КОН) 2 12 or in terms of the element of 3% zinc, (NH4) 2S04 9.5; Had 0.25.

Example 3 16 g of copper sulfate is dissolved in 84 ml of water, neutralized with ammonia gas to a pH of 10.5. A solution containing May% Cu (MN3) 4 (OH) 2 11: (NH / 02SO4 8.5, NH / jOH 10, water 70.5, 10 g of this solution is introduced into 130 g of a 75% urea solution. The mixture is evaporated and 100 g of fertilizer are obtained,%: Co (NH2) 2 98.0; Cu (MNZZHON) g 11.1 or 0.4% copper, calculated on the element, (NH4 2S040.85; HaO 0.25.

Example 4. 0.8 g of nickel sulphate is dissolved in 10 g of a 10% NIH-jOH solution. The resulting ammonia water solution of the composition,% in May: M (MH3) 4.3

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(NH / 02SCM 3.5; 3.7, introduced into 116 g of an 85% urea solution. A fertilizer of the composition is obtained,%: Co (NH2) 2 99; (MN3) 1 (OH) 2 0.5; H20 0.25; (NH.i} 2SCM 0.4%.

The essence of the method is the introduction of ammonium sulfate solutions of trace elements in the production cycle of urea after the first step of evaporation.

The preliminary dissolution of trace elements in an aqueous ammonia medium prevents the decomposition of urea when the concentration of trace elements exceeds 0.9%. According to the proposed method, the injected solution contains up to 10% ammonium hydroxide and the trace elements are already in the form of a complex, i.e. the consumption of ammonia MR is required, and the presence of such a quantity of ommyek inhibits the decomposition of urea and prevents the formation of biuret.

In tab. Table 1 presents data on the effect of ammonia-water solutions of microelements on the decomposition of urea.

Consumption of ammonia-water solutions depends on the concentration of trace elements in the solution. To add 1% supplement to carbamide, 10 kg of 10% or 100 kg of 1% or 200 kg of 0.5% aqueous solution is required. According to the proposed method, when dissolving sulfate salts of microelements in an ammonia medium, in addition to the microelement complex, ammonium sulfate is also formed, which increases strength and reduces the rate of dissolution of the granules.

In tab. Table 2 shows the results of studies of the effect of the amount of the added additive on the strength and rate of dissolution of the granules.

The composition of ammonia water solutions of microelements depends on the concentration of ammonia in the solution and the salt content of the microelements. When dissolved salts of trace elements in ammonia water the following reactions take place;

MeSCM + 2NH40H - Me (OH) z + (MNF3Sm Me (OH) 2 + 4NH40H - Me (MH3) 4 (OH) 2 + + 4H20

With a lack of ammonia, a hydroxide and ammonia complex can exist in the solution, and the hydroxide is in the form of a suspension, which quickly precipitates. Therefore, in the preparation of ammonia complexes of trace elements, there should be an excess of ammonia in the solution. The composition of ammonia-water solutions depends on the content of trace elements. The concentration of trace elements in these solutions depends on the nature of the trace element. Using

zinc sulphate, you can get a water-ammonia solution with a content of 10-11% zinc in terms of the element, whereas with copper to get a solution with a content of more than 5% copper is almost impossible.

The number of micronutrients injected depends on the needs of agriculture and is 0.2-3% per element of fertilizer. When dissolved 0.2%

trace element in ammonia water, depending on the amount and concentration of the aqueous ammonia solution, you can get a composition containing at least 2% Me (NH3) 4XOH) 2, (NH4) 2S04.NH40HHOCTanb water. The content of ammonia complex and ammonium sulphate depends on the trace element sulphate, the content on the concentration of ammonia in the ammonia-water solution and should not be

less than 2%, since with a lower ammonia content, the formation of insoluble hydroxides of trace elements is possible.

Upon receipt of saturated solutions of trace elements is the maximum achievable

the concentration of ammonia complexes does not exceed 25%, ammonium sulfate is 15%. The content of NH40H depends on the initial concentration of ammonia in the solution. In a manufacturing environment, commonly used

vodka-ammonia solutions with an ammonia content of 10-25%, and therefore, when sulfate salts of microelements are dissolved in them, solutions with the proposed compositions from minimum to maximum of trace elements are obtained. Only the ammonia content in the solution varies from 2 to 10%. Obtaining a concentration of ammonia complexes is almost impossible due to the formation of trace element hydroxide,

The proposed ammonia-water solutions are supposed to be injected before the second stage of evaporation, which is related to the technological parameters of the urea production process, namely, after

The first step of evaporation of the pH of the medium is maintained at 9-10, the pH of our solutions is 10-12. Therefore, the proposed method eliminates any possibility of the formation of insoluble trace element compounds.

with urea.

Complex salts of type Me (MNZ) 4ХОН) 2 act on urea identically depending on the amount introduced.

In tab. 3 shows the comparative

data well known and proposed methods.

In tab. 4 shows the effect of the ratio Me; NH, the formation of complexes of trace elements. .

As can be seen from the table. 4 ammonium complexes of microelements are fully integrated with the ratio Me: NH3. equal to 1: (6-10).

At a ratio of 6, metal hydroxide is in solution, which ultimately leads to clogging of equipment and communications. When the ratio Me: MNZ 4 - 6, depending on the conditions and time, the formation of compounds Me (NH3) or Me (MNZ) is possible. If the process is fast, a mixture of hydroxide, ammonia complex and ammonium sulfate is formed.

At a ratio of 6, only the ammonia complex and ammonium sulfate exist in the solution. The ammonium hydroxide content depends on how much more the Me: NN3 ratio takes. The presence of ammonium hydroxide at a ratio of 6 helps to prevent the decomposition of urea and the formation of biuret with the introduction of trace elements in urea in an amount of more than 0.9%.

To use the solution in the ratio of 10 is not economically profitable: high consumption of ammonia water and additional costs for catching it and returning to the process.

The introduction of ammonia-water solutions should be carried out after the first step of evaporation, when the pH of the melt reaches 9-10. If the solution is introduced earlier, the pH of the medium is low, the available free ammonia will not be enough, and the formation of insoluble compounds is possible.

microelements leading to clogging of equipment, communications, also leads to an increase in the degree of decomposition of urea and an increase in the content of biuret in the finished product.

The proposed method makes it possible to increase the strength of the granules, to reduce their dissolution rate and at the same time to reduce the decomposition of urea when introducing microelements.

Claims (3)

1. Method of obtaining microelement-containing urea, including the introduction of sulfates into the melt of urea melt microelements, evaporation of the melt in two steps and its granulation, characterized in that, in order to increase the strength and decrease the rate of dissolution of the granules while simultaneously reducing the decomposition of urea, the salt of sulfates. trace elements are pre-dissolved in an aqueous solution of ammonia with a ratio of Me: NH3 equal to 1: (b-10), to obtain aqueous ammonium sulfate solutions of trace elements containing, wt.% - Me (Mnz) 2-25. (MS) 25Sm 2-15, 2-10, water is the rest, where Me is copper, zinc, cobalt, nickel. 2. Method pop. 1, characterized in that 10-25% solutions of aqueous ammonia are used to dissolve the sulfates of trace elements. 3. Method according to paragraphs. 1 and 2, characterized in that the number of micronutrients injected is 0.2-3.0% by weight of the fertilizer. Table 1 table 2 Continued table. 2 Table 3 Table 4