Calcium magnesium phosphate fertilizer and preparation method thereof

Abstract

The application relates to the technical field of resource recycling, and provides a preparation method of calcium-magnesium-phosphorus fertilizer, which comprises the following steps: S1. adding a leaching agent into chlor-alkali industrial electrolytic salt mud to perform leaching, then performing solid-liquid separation to obtain filter residue for standby; S2. after the filter residue is dried, the filter residue is crushed, ground and sieved to obtain material A; S3. adding lime, silicon dioxide and calcium phosphate into the material A powder obtained in S2 in sequence, uniformly mixing, high-temperature roasting for a period of time, and then cooling and crushing to obtain the calcium-magnesium-phosphorus fertilizer; the industrial solid waste electrolytic salt mud is used as a raw material, waste utilization is carried out, the waste is made into the calcium-magnesium-phosphorus fertilizer conforming to the national standard, the waste is changed into treasure, part of traditional calcium-magnesium-phosphorus fertilizer can be replaced, meanwhile, the solid waste is avoided to be treated, and resource waste and environmental pollution are not caused.

Description

Technical Field

[0001] This invention relates to the field of resource recycling technology, and more specifically, to a calcium magnesium phosphate fertilizer and its preparation method. Background Technology

[0002] In the electrolytic production of potassium hydroxide using potassium chloride as a raw material, the raw material contains a large amount of impurities such as soil, calcium, and magnesium. Therefore, the raw material needs to undergo two brine refining processes. Refining primarily involves precipitating the soil and most of the calcium and magnesium ions from the raw material, resulting in salt mud. Traditionally, salt mud is a common solid waste in the chlor-alkali industry. Currently, it is generally disposed of by specialized companies, which significantly increases the treatment costs for enterprises and also causes some environmental impact during the treatment process.

[0003] Therefore, it is particularly important to know how to treat the electrolytic salt sludge in the chlor-alkali industry and turn it into a valuable resource, which can not only save enterprises treatment costs but also bring certain economic benefits. Summary of the Invention

[0004] Calcium magnesium phosphate fertilizer is an alkaline fertilizer without a clearly defined molecular formula and molecular weight. This fertilizer not only replenishes a large amount of phosphorus but also provides significant amounts of silicon, calcium, and magnesium. The inventors unexpectedly discovered that the filter residue remaining after water leaching of electrolytic salt mud from the chlor-alkali industry is a good raw material for producing calcium magnesium phosphate fertilizer. Specifically, by effectively separating potassium ions from the salt mud through water leaching, the remaining components are insoluble calcium, magnesium, silicon, and a small amount of phosphorus, making it an excellent raw material for calcium magnesium phosphate fertilizer production. Therefore, this invention uses water-leached salt mud filter residue as a base. By adding certain substances and undergoing special treatment, an effective slow-release calcium magnesium phosphate fertilizer can be produced, enabling the effective utilization of salt mud without resource waste or environmental pollution, while simultaneously reducing production costs for enterprises.

[0005] The present invention aims to provide a method for preparing calcium magnesium phosphate fertilizer, more specifically, a method for preparing calcium magnesium phosphate fertilizer using salt mud water leaching residue and calcium phosphate, quicklime and silicon dioxide.

[0006] The embodiments of the present invention are achieved through the following technical solutions:

[0007] A method for preparing a calcium magnesium phosphate fertilizer includes the following steps:

[0008] S1. Add leaching agent (water) to the chlor-alkali industrial electrolytic salt mud for leaching. The liquid-solid ratio of leaching agent to salt mud is 1.4-2.2:1. During leaching, stir and disperse at a speed of 200-500 r / min and react at 30-40℃ for 5-15 min. Then, separate the solid and liquid and take the filter residue for later use.

[0009] S2. After drying the filter residue, crush and grind it, then pass it through a 150-250 mesh sieve to obtain material A. The main components and contents (expressed as mass percentage) of the treated material A are as follows: calcium 7.2-20%, magnesium 10.41-15%, P2O5 11-18%, SiO2 22-30%; among which, the forms of calcium, magnesium and phosphorus are Ca5(PO4)3(OH), CaCO3 and Mg(OH)2, respectively.

[0010] S3. Add a small amount of quicklime, silicon dioxide and calcium phosphate to the powder A obtained in S2 in sequence, mix evenly, and then calcine at 1350℃~1400℃ for 3-5 hours. After cooling and crushing, calcium magnesium phosphate fertilizer is obtained.

[0011] Furthermore, through theoretical research and practical application, the inventors discovered that the optimal overall quality of the calcium magnesium phosphate fertilizer is achieved when the mass of quicklime is 15-25% of the mass of material A, the mass of silica is 5-20% of the mass of material A, and the mass of calcium phosphate is 10-30% of the mass of material A; more preferably, when the mass of quicklime is 20% of the mass of material A, the mass of silica is 15% of the mass of material A, and the mass of calcium phosphate is 20% of the mass of material A. Specifically, under the combined action of salt mud filter residue, quicklime, silica, and calcium phosphate, the quicklime reacts with Mg(OH)2 and CaCO3 in the salt mud filter residue with SiO2 at high temperature to generate CaSiO3 and MgSiO3, respectively. Calcium phosphate hardly reacts under these conditions. After the reaction is complete, a mixture of citrate-soluble calcium phosphate, CaSiO3, and MgSiO3 is obtained. After cooling and pulverizing, high-quality calcium magnesium phosphate fertilizer is obtained.

[0012] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

[0013] 1. This invention uses industrial solid waste electrolytic salt mud as raw material to utilize waste and turn it into calcium magnesium phosphate fertilizer, turning waste into treasure. It can replace part of the traditional calcium magnesium phosphate fertilizer, while avoiding the treatment of solid waste and preventing resource waste and environmental pollution.

[0014] 2. This invention utilizes the reaction of quicklime and Mg(OH)2 and CaCO3 in salt mud filter residue with SiO2 at high temperature to generate CaSiO3 and MgSiO3, respectively. Calcium phosphate hardly reacts under these conditions. After the reaction is complete, a mixture of citrate-soluble calcium phosphate, CaSiO3 and MgSiO3 is obtained. After cooling and pulverizing, high-quality calcium magnesium phosphate fertilizer is obtained. Moreover, only a small amount of calcium phosphate, quicklime and SiO2 are needed to obtain calcium magnesium phosphate fertilizer that meets national standards. The resource utilization rate is high and the product benefits are considerable. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a process flow diagram of the preparation method of the calcium magnesium phosphate fertilizer of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0018] Raw material description

[0019] The chlor-alkali industrial electrolytic salt mud used in each embodiment of this application is all from Huarong Chemical Co., Ltd., and its composition is shown in Table 1.

[0020] Table 1. Ion content in salt mud

[0021] <![CDATA[Ca 2+ ]]> <![CDATA[K + ]]> <![CDATA[Mg 2+ ]]> <![CDATA[Na + ]]> <![CDATA[Cl - ]]> <![CDATA[P2O5]]> <![CDATA[SiO2 and other trace elements]]> 7.20％ 21.27％ 10.41％ 0.96％ 20.69％ 10.33％ -

[0022] Example 1

[0023] A method for preparing a calcium magnesium phosphate fertilizer includes the following steps:

[0024] (1) Weigh 20g of chlor-alkali industrial electrolytic salt mud and add it to a beaker containing 28g of water while stirring. After the addition is complete, continue the reaction for 10min and control the reaction temperature at 30℃ and the stirrer speed at 300r / min. After the reaction stops, filter and wash the beaker wall and filter cake with a small amount of water. The filter cake is the salt mud water leaching residue.

[0025] (2) Dry the salt mud water-soaked residue to constant weight, then crush, grind, and pass through a 200-mesh sieve;

[0026] (3) Take 10g of the salt mud water leaching filter residue powder obtained in step (2), and add 2g of quicklime, 1g of SiO2 and 1g of calcium phosphate to it. After mixing evenly, calcine at 1400℃ for 5h. After cooling and crushing, calcium magnesium phosphate fertilizer is obtained. The obtained product is analyzed and tested. The specific indicators are as follows: the effective P2O5 content is 15.20%, the effective calcium content is 20.67%wt, the effective magnesium content is 8.63%wt, and the water-soluble SiO2 content is 24.56%, which meets the national standard requirements (GB / T20412—2021) for calcium magnesium phosphate fertilizer indicators.

[0027] Example 2

[0028] A method for preparing a calcium magnesium phosphate fertilizer includes the following steps:

[0029] (1) Weigh 20g of chlor-alkali industrial electrolytic salt mud and add it to a beaker containing 36g of water while stirring. After the addition is complete, continue the reaction for 10min and control the reaction temperature at 40℃ and the stirrer speed at 500r / min. After the reaction stops, filter and wash the beaker wall and filter cake with a small amount of water. The filter cake is the salt mud water leaching residue.

[0030] (2) Dry the salt mud water-soaked residue to constant weight, then crush, grind, and pass through a 200-mesh sieve;

[0031] (3) Take 10g of the salt mud water leaching filter residue powder obtained in step (2), and add 2g of quicklime, 2g of SiO2 and 3g of calcium phosphate to it. After mixing evenly, calcine at 1350℃ for 3h. After cooling and crushing, calcium magnesium phosphate fertilizer is obtained. The obtained product is analyzed and tested. The specific indicators are as follows: the effective P2O5 content is 13.89%, the effective calcium content is 22.61%wt, the effective magnesium content is 7.70%wt, and the water-soluble SiO2 content is 25.57%, which meets the national standard requirements for calcium magnesium phosphate fertilizer indicators.

[0032] Example 3

[0033] A method for preparing a calcium magnesium phosphate fertilizer includes the following steps:

[0034] (1) Weigh 20g of chlor-alkali industrial electrolytic salt mud and add it to a beaker containing 44g of water while stirring. After the addition is complete, continue the reaction for 15min and control the reaction temperature at 35℃ and the stirrer speed at 350r / min. After the reaction stops, filter and wash the beaker wall and filter cake with a small amount of water. The filter cake is the salt mud water leaching residue.

[0035] (2) Dry the salt mud water-soaked residue to constant weight, then crush, grind, and pass through a 200-mesh sieve;

[0036] (3) Take 10g of the salt mud water leaching filter residue powder obtained in step (2), and add 2g of quicklime, 1.5g of SiO2 and 2g of calcium phosphate to it. After mixing evenly, calcine at 1400℃ for 5h. After cooling and crushing, calcium magnesium phosphate fertilizer is obtained. The obtained product is analyzed and tested. The specific indicators are as follows: the effective P2O5 content is 13.48%, the effective calcium content is 22.86%wt, the effective magnesium content is 7.24%wt, and the water-soluble SiO2 content is 23.14%, which meets the national standard requirements for calcium magnesium phosphate fertilizer indicators.

[0037] Example 4

[0038] A method for preparing a calcium magnesium phosphate fertilizer includes the following steps:

[0039] (1) Weigh 20g of chlor-alkali industrial electrolytic salt mud and add it to a beaker containing 30g of water while stirring. After the addition is complete, continue the reaction for 10min and control the reaction temperature at 40℃ and the stirrer speed at 400r / min. After the reaction stops, filter and wash the beaker wall and filter cake with a small amount of water. The filter cake is the salt mud water leaching residue.

[0040] (2) Dry the salt mud water-soaked residue to constant weight, then crush, grind, and pass through a 200-mesh sieve;

[0041] (3) Take 10g of the salt mud water leaching filter residue powder obtained in step (2), and add 1.5g of quicklime, 1.5g of SiO2 and 1.5g of calcium phosphate to it. After mixing evenly, calcine at 1380℃ for 4h. After cooling and crushing, calcium magnesium phosphate fertilizer is obtained. The obtained product is analyzed and tested. The specific indicators are as follows: the effective P2O5 content is 14.16%, the effective calcium content is 23.74%wt, the effective magnesium content is 7.42%wt, and the water-soluble SiO2 content is 23.48%, which meets the national standard requirements for calcium magnesium phosphate fertilizer indicators.

[0042] Example 5

[0043] A method for preparing a calcium magnesium phosphate fertilizer includes the following steps:

[0044] (1) Weigh 20g of chlor-alkali industrial electrolytic salt mud and add it to a beaker containing 35g of water while stirring. After the addition is complete, continue the reaction for 10min and control the reaction temperature at 40℃ and the stirrer speed at 450r / min. After the reaction stops, filter and wash the beaker wall and filter cake with a small amount of water. The filter cake is the salt mud water leaching residue.

[0045] (2) Dry the salt mud water-soaked residue to constant weight, then crush, grind, and pass through a 200-mesh sieve;

[0046] (3) Take 10g of the salt mud water leaching filter residue powder obtained in step (2), and add 1.8g of quicklime, 1.4g of SiO2 and 2.5g of calcium phosphate to it. After mixing evenly, calcine at 1360℃ for 4.5h. After cooling and crushing, calcium magnesium phosphate fertilizer is obtained. The obtained product is analyzed and tested. The specific indicators are as follows: the effective P2O5 content is 14.96%, the effective calcium content is 23.25%wt, the effective magnesium content is 8.07%wt, and the water-soluble SiO2 content is 21.37%, which meets the national standard requirements for calcium magnesium phosphate fertilizer indicators.

[0047] Example 6

[0048] A method for preparing a calcium magnesium phosphate fertilizer includes the following steps:

[0049] (1) Weigh 20g of chlor-alkali industrial electrolytic salt mud and add it to a beaker containing 40g of water while stirring. After the addition is complete, continue the reaction for 8min and control the reaction temperature at 40℃ and the stirrer speed at 400r / min. After the reaction stops, filter and wash the beaker wall and filter cake with a small amount of water. The filter cake is the salt mud water leaching residue.

[0050] (2) Dry the salt mud water-soaked residue to constant weight, then crush, grind, and pass through a 200-mesh sieve;

[0051] (3) Take 10g of the salt mud water leaching filter residue powder obtained in step (2), and add 1.7g of quicklime, 1.4g of SiO2 and 1.6g of calcium phosphate to it. After mixing evenly, calcine at 1400℃ for 4h. After cooling and crushing, calcium magnesium phosphate fertilizer is obtained. The obtained product is analyzed and tested. The specific indicators are as follows: the effective P2O5 content is 14.03%, the effective calcium content is 22.95%wt, the effective magnesium content is 8.41%wt, and the water-soluble SiO2 content is 23.28%, which meets the national standard requirements for calcium magnesium phosphate fertilizer indicators.

[0052] Example 7

[0053] A method for preparing a calcium magnesium phosphate fertilizer includes the following steps:

[0054] (1) Weigh 20g of chlor-alkali industrial electrolytic salt mud and add it to a beaker containing 35g of water while stirring. After the addition is complete, continue the reaction for 10min and control the reaction temperature at 38℃ and the stirrer speed at 500r / min. After the reaction stops, filter and wash the beaker wall and filter cake with a small amount of water. The filter cake is the salt mud water leaching residue.

[0055] (2) Dry the salt mud water-soaked residue to constant weight, then crush, grind, and pass through a 200-mesh sieve;

[0056] (3) Take 10g of the salt mud water leaching filter residue powder obtained in step (2), and add 1.8g of quicklime, 1.6g of SiO2 and 2.6g of calcium phosphate to it. After mixing evenly, calcine at 1370℃ for 3.5h. After cooling and crushing, calcium magnesium phosphate fertilizer is obtained. The obtained product is analyzed and tested. The specific indicators are as follows: the effective P2O5 content is 15.36%, the effective calcium content is 24.07%wt, the effective magnesium content is 7.26%wt, and the water-soluble SiO2 content is 22.41%, which meets the national standard requirements for calcium magnesium phosphate fertilizer indicators.

[0057] Example 8

[0058] A method for preparing a calcium magnesium phosphate fertilizer includes the following steps:

[0059] (1) Weigh 20g of chlor-alkali industrial electrolytic salt mud and add it to a beaker containing 35g of water while stirring. After the addition is complete, continue the reaction for 10min and control the reaction temperature at 40℃ and the stirrer speed at 400r / min. After the reaction stops, filter and wash the beaker wall and filter cake with a small amount of water. The filter cake is the salt mud water leaching residue.

[0060] (2) Dry the salt mud water-soaked residue to constant weight, then crush, grind, and pass through a 200-mesh sieve;

[0061] (3) Take 10g of the salt mud water leaching filter residue powder obtained in step (2), and add 2.2g of quicklime, 1.9g of SiO2 and 2.8g of calcium phosphate to it. After mixing evenly, calcine at 1370℃ for 3.5h. After cooling and crushing, calcium magnesium phosphate fertilizer is obtained. The obtained product is analyzed and tested. The specific indicators are as follows: the effective P2O5 content is 12.66%, the effective calcium content is 23.15%wt, the effective magnesium content is 7.53%wt, and the water-soluble SiO2 content is 24.09%, which meets the national standard requirements for calcium magnesium phosphate fertilizer indicators.

[0062] Example 9

[0063] A method for preparing a calcium magnesium phosphate fertilizer includes the following steps:

[0064] (1) Weigh 20g of chlor-alkali industrial electrolytic salt mud and add it to a beaker containing 36g of water while stirring. After the addition is complete, continue the reaction for 12min and control the reaction temperature at 40℃ and the stirrer speed at 300r / min. After the reaction stops, filter and wash the beaker wall and filter cake with a small amount of water. The filter cake is the salt mud water leaching residue.

[0065] (2) Dry the salt mud water-soaked residue to constant weight, then crush, grind, and pass through a 200-mesh sieve;

[0066] (3) Take 10g of the salt mud water leaching filter residue powder obtained in step (2), and add 2g of quicklime, 0.5g of SiO2 and 1g of calcium phosphate to it. After mixing evenly, calcine at 1360℃ for 3.2h. After cooling and crushing, calcium magnesium phosphate fertilizer is obtained. The obtained product is analyzed and tested. The specific indicators are as follows: the effective P2O5 content is 13.36%, the effective calcium content is 20.48%wt, the effective magnesium content is 8.77%wt, and the water-soluble SiO2 content is 20.09%, which meets the national standard requirements for calcium magnesium phosphate fertilizer indicators.

[0067] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a calcium magnesium phosphate fertilizer, characterized in that, Includes the following steps: S1. Add a leaching agent to the salt mud for leaching, then separate the solid and liquid and collect the filter residue for later use; wherein, the leaching agent is water, the liquid-solid ratio of the leaching agent to the salt mud is 1.4-2.2:1, the reaction temperature is 30-40℃, and the reaction time is 5-15min; during leaching, stir and disperse at a speed of 200-500r / min; S2. After drying the filter residue, crush and grind it and then sieve it to obtain material A. The powder of material A is ground and then sieved through a 150-250 mesh sieve. S3. Add quicklime, silicon dioxide, and calcium phosphate sequentially to the powder A obtained in S2, mix evenly, and then calcine at 1350℃~1400℃ for 3-5 h. After cooling and pulverizing, calcium magnesium phosphate fertilizer is obtained. The mass of quicklime is 15-25% of the mass of material A, the mass of silicon dioxide is 5-20% of the mass of material A, and the mass of calcium phosphate is 10-30% of the mass of material A.

2. The method for preparing calcium magnesium phosphate fertilizer according to claim 1, characterized in that, In S2, the mass of quicklime is 20% of the mass of material A, the mass of silicon dioxide is 15% of the mass of material A, and the mass of calcium phosphate is 20% of the mass of material A.

3. A calcium magnesium phosphate fertilizer, characterized in that, It is prepared by any one of the preparation methods of claims 1-2.

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