RU2447017C2 - Method for chemical enrichment of high-silica phosphorites from kimovsk deposit - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to the industry of mineral fertilisers and can be used for chemical enrichment of poor phosphate material with high content of silicon dioxide, and specifically high-silica phosphorites from the Kimovsk deposit. The method for chemical enrichment involves mixing Kimovsk phosphorites containing 40.5 wt % SiO₂ with ammonium fluoride with addition of 1-3 wt % magnesium sulphate. Ammonium fluoride is taken in stoichiometric amount of 100-135% for formation of ammonium hexafluorosilicate. Thermal treatment is carried out using microwaves at temperature 149 - 180°C, followed by sublimation of the obtained ammonium hexafluoride at temperature 301 - 400°C. Phosphorus pentoxide content after chemical enrichment is equal to 20.34 - 21.85 wt % P₂O₅. The degree of desiliconisation of the phosphorite is equal to 99.5%.

EFFECT: method enables to cut duration of the desiliconisation process of phosphorites from the Kimovsk deposit, and also reduces consumption of ammonium fluoride and energy resources.

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Description

The invention relates to the industry of mineral fertilizers and can be used for chemical enrichment of poor phosphate raw materials with a high content of silicon dioxide.

A known method of chemical enrichment of high-silicon phosphates by treatment with ammonium fluoride in an amount of 100-300% of the stoichiometry for the formation of ammonium hexafluorosilicate at a temperature of 200-300 ° C [SU No. 1182016, class. C05B 11/02, 09/30/85. Bull. No. 36].

In this case, the interaction of ammonium fluoride with silicon dioxide contained in the raw material, and enrichment of the raw material due to the sublimation of the formed ammonium hexafluorosilicate. Other disadvantages of this method are the increased consumption of ammonium fluoride due to unproductive sublimation of it in a given temperature range and the long duration of the process.

Closest to the proposed method in technical essence is a method of chemical enrichment of high-silicon phosphorites, including mixing them with ammonium fluoride, heat treatment and sublimation of the product, while the heat treatment of the mixtures is carried out at 150-190 ° C followed by sublimation at 350-550 ° C [SU No. 1781168, class C01B 25/01, 12/15/92. Bull. No. 46].

The disadvantage of the patent is that the complete composition of phosphorites subjected to heat treatment is not given, but only the content of P ₂ O ₅ and SiO ₂ , although the increased content of sesquioxides Al ₂ O ₃ and Fe ₂ O ₃ seriously complicate the process of chemical enrichment of phosphorites.

In addition, the disadvantage of this method is the elevated temperature, reaching 550 ° C at a rate of ammonium fluoride of 140% of stoichiometric and prolonged heat treatment of 1 hour, which leads to an increased consumption of ammonium fluoride and energy.

Disclosure of the invention.

The main technical problem to which the present invention is directed is to implement a method for the chemical enrichment of high-silicon phosphorites of the Kimovsky deposit, subject to a reduction in the time of the process of desalination of phosphorites, in reducing the consumption of ammonium fluoride and energy.

The problem is solved in a method for the chemical enrichment of high-silicon phosphorites of the Kimovsky deposit, including mixing phosphorites with ammonium fluoride, heat treatment and sublimation of the product, moreover, when mixed, phosphorites with SiO ₂ content _of 40.5 wt.% Are taken, and ammonium fluoride is taken in an amount of 100-135% from stoichiometry to the formation of ammonium hexafluorosilicate, magnesium sulfate is additionally added to the mixture in an amount of 1.0-3.0 wt.%, while the mixtures are heat treated in a microwave oven at a temperature of 149-180 ° C, followed by sublimation at a rate ture 301-400 ° C.

The main distinguishing features of the method are that when Kimov phosphorites with a content of SiO _{2 of} 40.5 wt.% Are mixed, 1-3 wt.% Of magnesium sulfate is added, and ammonium fluoride is taken in an amount of 100-135% of stoichiometry for the formation of ammonium hexafluorosilicate, wherein the heat treatment of the mixtures is carried out in a microwave oven at a temperature of 149-180 ° C, followed by sublimation at a temperature of 301-400 ° C.

The method in accordance with the present invention allows to obtain phosphorite from the Kimov deposit with a phosphorus pentoxide content of 20.34-21.85 wt.% P ₂ O ₅ , which can be used in the production of complex and nitrogen-phosphorus fertilizers.

The present invention meets the condition of patentability - novelty, because in the prior art it was not possible to find a technical solution, the essential features of which completely coincide with all the features available in the independent claim. The invention also meets the condition of patentability - inventive step, since the prior art does not contain a description of the technical solution, the hallmarks of which are aimed at solving the technical problem that the present invention is directed to.

An example implementation of the method

Example 1. 100.0 kg Kimovsky phosphorite containing, wt.%: P ₂ O ₅ - 14.4; CaO 22.3; Fe ₂ O ₃ - 9.9; SiO ₂ - 40.5; Al ₂ O ₃ - 5.8; Na ₂ O - 0.40; K ₂ O - 1.38; MgO - 0.80; F 1.09; CO ₂ 1.80; S _total - 0.3; H ₂ O - 1.3, mixed with 149.85 kg of ammonium fluoride, which corresponds to a 100% stoichiometric norm for the production of ammonium hexafluorosilicate. To the resulting mixture add 1.0 kg of MgSO ₄ . The resulting mixture is placed in a microwave oven, where we carry out preliminary heat treatment at a temperature of 149 ° C for 15 minutes. This results in 208.94 kg of phosphorite containing 8.90 wt.% SiO ₂ and 70.09 kg (NH ₄ ) ₂ SiF ₆ , 27.1 kg of NH ₃ and 14.2 kg of H ₂ O are released into the gas phase. Then, the formed ammonium hexafluorosilicate is sublimated in a microwave oven for 45 min at a temperature of 301 ° C. In this case, 70.8 kg of phosphorite containing 20.34 wt.% P ₂ O ₅ and 4.9 wt.% SiO ₂ are obtained. The degree of extraction of SiO ₂ is 90.5%, and the content of P ₂ O ₅ in the phosphorite reached 20.34 wt.% P ₂ O ₅ .

Example 2. 100.0 kg of Kimovsky phosphorite of the same composition are mixed with 202.3 kg of ammonium fluoride, which corresponds to 135% of the stoichiometric norm for the production of ammonium hexafluorosilicate. To the resulting mixture was added 3.0 kg of MgSO ₄ . Maintain the resulting mixture in a microwave oven at a temperature of 180 ° C for 15 minutes. This results in 248.5 kg of phosphorite containing 2.88 wt.% SiO ₂ and 102.1 kg (NH ₄ ) ₂ SiF ₆ , 39.02 kg of NH ₃ and 20.63 kg of H ₂ O are released into the gas phase. Then the ammonium hexafluorosilicate formed is sublimated at a temperature of 400 ° C for 30 minutes. This gives 65.9 kg of phosphorite containing 21.85 wt.% P ₂ O ₅ and 0.31 wt.% SiO ₂ . The degree of desilicon phosphorite from SiO ₂ is 99.5%, and the content of P ₂ O ₅ in Kimovsky phosphorite was 21.85 wt.% P ₂ O ₅ .

Example 3. The process is conducted as described in example 1, but with the following differences.

100.0 kg of Kimovsky phosphorite is mixed with 146.85 kg of ammonium fluoride, which corresponds to 98% of the stoichiometric norm for the production of ammonium hexafluorosilicate. To the resulting mixture was added 0.95 kg of MgSO ₄ . The resulting mixture is placed in a microwave oven, where we carry out preliminary heat treatment at a temperature of 147 ° C for 15 minutes. This results in 204.76 kg of phosphorite containing 9.04 wt.% SiO ₂ and 68.6 kg (NH ₄ ) SiF ₆ , 25.6 kg of NH ₃ and 13.8 kg of H ₂ O are released into the gas phase. Then formed ammonium hexafluorosilicate is sublimated in a microwave oven for 45 min at a temperature of 298 ° C. This gives 72.6 kg of phosphorite containing 19.6 wt.% P ₂ O ₅ and 5.6 wt.% SiO ₂ . The degree of extraction of SiO ₂ is 89.97%, and the content of P ₂ O ₅ in the phosphorite was 19.6 wt.% P ₂ O ₅ .

Example 4. 100.0 kg of Kimovsky phosphorite of the same composition are mixed with 205.3 kg of ammonium fluoride, which corresponds to 137% of the stoichiometric norm for the production of ammonium hexafluorosilicate. To the resulting mixture was added 3.1 kg of MgSO ₄ . Maintain the resulting mixture in a microwave oven at a temperature of 182 ° C for 15 minutes. This results in 251.4 kg of phosphorite containing 3.21 wt.% SiO ₂ and 98.3 kg (NH ₄ ) SiF ₆ , 39.8 kg of NH ₃ and 21.06 kg of H ₂ O are released into the gas phase. Then ammonium hexafluorosilicate formed is sublimated at a temperature of 402 ° C for 33.0 minutes. This gives 66.4 kg of phosphorite containing 21.65 wt.% P ₂ O ₅ and 0.52 wt.% SiO ₂ . The degree of desilicon phosphorite from SiO ₂ is 98.7%, and the content of P ₂ O ₅ in Kimovsky phosphorite decreased to 21.65 wt.% P ₂ O ₅ .

It should be noted that when going beyond the lower limit of the concentrations of magnesium sulfate and ammonium fluoride specified in the first paragraph of the claims, the process performance decreases. When lowering the temperature of heat treatment of a mixture of phosphorite, ammonium fluoride and magnesium sulfate and subsequent sublimation of ammonium hexafluorosilicate, substandard raw materials are obtained with the required composition of 20.34-21.85 wt.% P ₂ O ₅ .

When the concentration of magnesium sulfate and ammonium fluoride is exceeded, as well as the temperatures of the heat treatment of a mixture of phosphorite, ammonium fluoride and magnesium sulfate and the subsequent sublimation of ammonium hexafluorosilicate, the consumption coefficients for raw materials and energy costs significantly increase.

The proposed method for the chemical enrichment of Kimov phosphorites due to the introduction of magnesium sulfate as 1-3 wt.% MgSO ₄ allows to reduce the consumption of ammonium fluoride, and subsequent heat treatment of mixtures of phosphate and ammonium fluoride, as well as sublimation of ammonium hexafluorosilicate using microwave ovens, allows to reduce the specific energy consumption more than 3 times.

Practical applicability

The invention with the greatest efficiency can be used in the chemical industry in the production of granular complex and nitrogen-phosphorus fertilizers.

Claims (2)

1. The method of chemical enrichment of high-silicon phosphorites of the Kimovsky deposit, including mixing them with ammonium fluoride, heat treatment and sublimation of the product, characterized in that when enriching phosphorites with a content of SiO _{2 of} 40.5 wt.% Add 1-3 wt.% Magnesium sulfate, and ammonium fluoride is taken in an amount of 100-135% of the stoichiometry for the formation of ammonium hexafluorosilicate, while the heat treatment of the mixtures is carried out using microwave at a temperature of 149-180 ° C, followed by sublimation at a temperature of 301-400 ° C. 2. The method of chemical enrichment of high-silicon phosphorites of the Kimovsky deposit according to claim 1, characterized in that the phosphorus pentoxide content after enrichment is 20.34-21.85 wt.% P ₂ O ₅ .