Method for preparing silicon-calcium-potassium-magnesium fertilizer through pre-activation

Abstract

The invention discloses a method for preparing a silicon-calcium-potassium-magnesium fertilizer by pre-activation, which comprises the following steps: (1) pre-activation: mixing a solid raw material consisting of phosphogypsum, dolomite and potassium feldspar with an activation solution accounting for 10-15% of the mass of the solid raw material, and uniformly stirring to obtain a pre-activated material; and (2) sintering: sintering the pre-activated material at high temperature, and cooling after sintering to obtain the silicon-calcium-potassium-magnesium fertilizer. According to the silicon-calcium-potassium-magnesium fertilizer and the preparation method thereof disclosed by the invention, the solid raw materials are pre-activated by utilizing the activating solution, and the decomposition of crystal structures of the solid raw materials is promoted to a certain extent, so that the content of water-soluble and citric acid-soluble elements is effectively increased, the absorption of crops is facilitated, and the prepared silicon-calcium-potassium-magnesium fertilizer contains silicon, calcium, potassium, magnesium, sulfur and other various trace beneficial element components, and has a good application prospect. Mineral nutrients are comprehensive and balanced, and crop nutrition can be kept balanced.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of calcium-silicon-potassium-magnesium fertilizer, and in particular to a method for pre-activating the preparation of calcium-silicon-potassium-magnesium fertilizer. Background Art

[0002] Calcium-silicon-potassium-magnesium fertilizer is an alkaline fertilizer formed by calcining phosphogypsum, potassium feldspar, etc. at high temperature, and contains main nutrient elements such as silicon, calcium, potassium, and magnesium required by rice. It can not only effectively increase the yield of rice and the pH of the plough layer soil of paddy fields, increase the content of base ions in the plough layer soil, but also supplement a variety of macro, medium, and trace elements. It can effectively overcome the deficiency that lime and the like are likely to cause soil compaction, has good application effects on various crops, and has little impact on the soil environment. It is a new type of environmental protection soil conditioner. However, the content of water-soluble and citrate-soluble elements in the existing calcium-silicon-potassium-magnesium fertilizer is relatively low, resulting in crops being unable to quickly and effectively absorb nutrients. Therefore, it is necessary to increase the content of water-soluble and citrate-soluble elements in calcium-silicon-potassium-magnesium fertilizer so that crops can quickly and effectively absorb nutrients.

[0003] Chinese Patent with application publication number CN110437106A and application publication date November 12, 2019 discloses a method for using citric acid to enhance calcium-silicon-potassium-magnesium fertilizer and its preparation method, including the following raw materials in parts by mass: 152-188 parts of calcium-silicon-potassium-magnesium fertilizer and 12-48 parts of citric acid. This method directly mixes calcium-silicon-potassium-magnesium fertilizer with citric acid and then performs nodulization to obtain citric acid-enhanced calcium-silicon-potassium-magnesium fertilizer, which has the following defects: extracting the nutrient elements that can be absorbed by plants in the soil through citric acid to increase the dissolution of poorly soluble nutrients does not solve the problem that the content of water-soluble and citrate-soluble elements in calcium-silicon-potassium-magnesium fertilizer is relatively low, resulting in crops being unable to quickly and effectively absorb nutrients. Summary of the Invention

[0004] The present invention is to solve the problem that the content of water-soluble and citrate-soluble elements in the existing calcium-silicon-potassium-magnesium fertilizer is relatively low and is not easily absorbed by crops, and provides a method for pre-activating the preparation of calcium-silicon-potassium-magnesium fertilizer. The process steps are simple, and it can effectively increase the content of water-soluble and citrate-soluble elements beneficial to crops, which is beneficial to crop absorption.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A method for pre-activating the preparation of calcium-silicon-potassium-magnesium fertilizer of the present invention includes the following steps: (1)Pre-activation: After mixing the solid raw materials with the activation liquid and stirring evenly, a pre-activated material is obtained. The solid raw materials consist of phosphogypsum, dolomite, and potassium feldspar. The mass of the activation liquid is 10-15% of the mass of the solid raw materials. The phosphogypsum in the present invention can be the solid waste generated from the reaction of phosphate rock and sulfuric acid in the wet-process phosphoric acid production process. Its main component is CaSO4∙2H2O, and it also contains some components such as silica. It can decompose into elements such as calcium, sulfur, and silicon required by crops at high temperatures. As one of the raw materials for silicon-calcium-potassium-magnesium fertilizer, this has great significance for the resource utilization of phosphogypsum. The activation liquid can promote the decomposition of the crystal structure of the solid raw materials to a certain extent, so as to effectively increase the content of water-soluble and citrate-soluble elements. Dolomite can decompose under high-temperature conditions, providing a reducing atmosphere while providing calcium and magnesium elements to promote the decomposition of phosphogypsum, thereby enhancing the overall activation degree of the product.

[0006] (2)Sintering: The pre-activated material is subjected to high-temperature sintering and then cooled to obtain silicon-calcium-potassium-magnesium fertilizer.

[0007] Preferably, in step (1), the mass percentage contents of phosphogypsum, dolomite, and potassium feldspar in the solid raw materials are: dolomite 15-30%, potassium feldspar 30-35%, and the balance is phosphogypsum.

[0008] Preferably, in step (1), the particle sizes of the phosphogypsum, dolomite, and potassium feldspar in the solid raw materials are all above 200 mesh.

[0009] Preferably, in step (1), the activation liquid is an oxalic acid aqueous solution or a citric acid aqueous solution.

[0010] Preferably, the activation liquid is an oxalic acid aqueous solution with a mass concentration of 6-9% or a citric acid aqueous solution with a mass concentration of 2-3%.

[0011] Preferably, in step (2), the sintering temperature is 850-1050 °C and the sintering time is 0.5-1.5 h.

[0012] Therefore, the present invention has the following beneficial effects: (1)Using the activation liquid to pre-activate the solid raw materials can promote the decomposition of the crystal structure of the solid raw materials to a certain extent, thereby effectively increasing the content of water-soluble and citrate-soluble elements, which is beneficial to crop absorption. (2)The solid raw materials consist of phosphogypsum, dolomite, and potassium feldspar. The prepared silicon-calcium-potassium-magnesium fertilizer contains silicon, calcium, potassium, magnesium, sulfur, and other various trace beneficial elements. The mineral nutrients are comprehensive and balanced, which can ensure the balance of crop nutrition. (3)The preparation method has simple process steps and strong operability, and is suitable for large-scale industrial promotion and application. Specific embodiments

[0013] The present invention will be further described below in conjunction with specific embodiments.

[0014] In the present invention, all devices and raw materials can be purchased from the market or are commonly used in this industry. The methods in the following embodiments are all conventional methods in this field unless otherwise specified.

[0015] Example 1 (1) Pre-activation: After mixing the solid raw materials with the activation liquid and stirring evenly, a pre-activated material is obtained. The solid raw materials are composed of 45% phosphogypsum, 20% dolomite, and 35% potassium feldspar by mass percentage, and the activation liquid is an oxalic acid aqueous solution with a mass concentration of 8%. The mass of the activation liquid is 12.5% of the mass of the solid raw materials. (2) Sintering: The pre-activated material is subjected to high-temperature sintering at a sintering temperature of 950 °C for 1 h, and then cooled after sintering to obtain a silicon-calcium-potassium-magnesium fertilizer.

[0016] Example 2 (1) Pre-activation: After mixing the solid raw materials with the activation liquid and stirring evenly, a pre-activated material is obtained. The solid raw materials are composed of 50% phosphogypsum, 15% dolomite, and 35% potassium feldspar by mass percentage, and the activation liquid is an oxalic acid aqueous solution with a mass concentration of 6%. The mass of the activation liquid is 15% of the mass of the solid raw materials. (2) Sintering: The pre-activated material is subjected to high-temperature sintering at a sintering temperature of 1050 °C for 0.5 h, and then cooled after sintering to obtain a silicon-calcium-potassium-magnesium fertilizer.

[0017] Example 3 (1) Pre-activation: After mixing the solid raw materials with the activation liquid and stirring evenly, a pre-activated material is obtained. The solid raw materials are composed of 40% phosphogypsum, 30% dolomite, and 30% potassium feldspar by mass percentage, and the activation liquid is a citric acid aqueous solution with a mass concentration of 3%. The mass of the activation liquid is 10% of the mass of the solid raw materials. (2) Sintering: The pre-activated material is subjected to high-temperature sintering at a sintering temperature of 850 °C for 1.5 h, and then cooled after sintering to obtain a silicon-calcium-potassium-magnesium fertilizer.

[0018] Within the scope of the examples, the obtained silicon-calcium-potassium-magnesium fertilizer products comply with the relevant regulations in "GBT36207-2018 Silicon-Calcium-Potassium-Magnesium Fertilizer".

[0019] The above-described examples are only a preferred solution of the present invention and do not impose any form of limitation on the present invention. There are other variations and modifications without exceeding the technical solutions recorded in the claims.

Claims

1. A method for preparing silicon-calcium-potassium-magnesium fertilizer by pre-activation, characterized in that It includes the following steps: (1) Pre-activation: After mixing the solid raw materials with the activation liquid and stirring evenly, a pre-activated material is obtained. The solid raw materials consist of phosphogypsum, dolomite and potassium feldspar, and the mass of the activation liquid is 10-15% of the mass of the solid raw materials; (2) Sintering: Subject the pre-activated material to high-temperature sintering, and cool it after sintering to obtain silicon-calcium-potassium-magnesium fertilizer.

2. The method for preparing calcium-silicon-potassium-magnesium fertilizer by pre-activation according to claim 1, characterized in that, In step (1), the mass percentage contents of phosphogypsum, dolomite and potassium feldspar in the solid raw materials are: 15-30% of dolomite, 30-35% of potassium feldspar, and the balance is phosphogypsum.

3. A method for preparing calcium-silicon-potassium-magnesium fertilizer by pre-activation according to claim 1 or 2, characterized in that, In step (1), the particle sizes of phosphogypsum, dolomite and potassium feldspar in the solid raw materials are all above 200 mesh.

4. A method for preparing calcium-silicon-potassium-magnesium fertilizer by pre-activation according to claim 1, characterized in that, In step (1), the activation liquid is an oxalic acid aqueous solution or a citric acid aqueous solution.

5. A method for preparing calcium-silicon-potassium-magnesium fertilizer by pre-activation according to claim 4, characterized in that, The activation liquid is an oxalic acid aqueous solution with a mass concentration of 6-9% or a citric acid aqueous solution with a mass concentration of 2-3%.

6. A method for preparing calcium-silicon-potassium-magnesium fertilizer by pre-activation according to claim 1, characterized in that, In step (2), the sintering temperature is 850-1050 °C, and the sintering time is 0.5-1.5 h.