Production method for preparing potassium humate fertilizer from potassium feldspar through continuous high-pressure hydrothermal method

Abstract

The invention discloses a production method for preparing a potassium humate fertilizer through continuous high-pressure hydrothermal reaction of potassium feldspar, and relates to a wet grinding pulping process, a hydrothermal reaction process, a flash evaporation filter pressing process, a humic acid modified potassium fertilizer preparation process and a causticization and humic acid modified silicon-calcium fertilizer preparation process. The preparation method comprises the following steps: firstly, carrying out high-pressure tubular hydrothermal reaction and tower-type delayed reaction on potassium feldspar alkaline ore pulp prepared by fine grinding to prepare potassium aluminosilicate and calcium silicate, mixing alkaline potassium aluminosilicate filter residues obtained by filtering with humic acid, modifying, granulating and drying to obtain a humic acid coated long-acting slow-release potassium fertilizer product. The alkaline calcium silicate filtrate and lime are subjected to a causticization reaction to obtain a KOH solution, the KOH solution is returned to a wet pulping process to be recycled, and the alkaline calcium silicate and the humic acid are mixed, modified, granulated and dried to produce the humic acid coated long-acting slow-release silicon-calcium fertilizer product.

Description

1. Technical Field

[0001] The invention provides a production method for preparing potassium humate fertilizer by continuous high-pressure hydrothermal method using potassium feldspar, and relates to the field of fine chemicals. 2. Background technology

[0002] Potassium is one of the three essential nutrients for crop growth. It can enhance the ability of crops to resist drought, cold, disease, salt and lodging, and has a significant effect on stable and high yields of crops. Therefore, almost every crop needs to be applied with appropriate amounts of potassium fertilizer. As a large agricultural country with a vast territory, my country has a huge demand gap for potassium fertilizer. However, due to the extremely scarce water-soluble potassium salt resources used as potassium fertilizer, its reserves are equivalent to about 450 million tons of K2O, accounting for only 2.647% of the world's total. As the world's largest potassium fertilizer demander, my country's external dependence is as high as 50%.

[0003] However, my country's water-insoluble potassium ore resources are extremely rich, with wide distribution, high quality, and easy mining. Among them, potassium feldspar is the most representative, distributed in 23 provinces and regions including Inner Mongolia, Anhui, Heilongjiang, Sichuan, and Xinjiang, with estimated reserves of more than 20 billion tons. Since potassium feldspar has a three-dimensional framework structure formed by Si-Al-O tetrahedrons, its chemical properties are extremely stable and it is almost not decomposed by other acids and alkalis except concentrated sulfuric acid and hydrofluoric acid at room temperature and pressure. Therefore, the key to extracting potassium salts is to efficiently decompose potassium feldspar and convert the water-insoluble potassium into water-soluble potassium compounds.

[0004] There are more than ten process methods for producing potassium fertilizer using potassium feldspar at home and abroad, namely low-temperature decomposition, hydrothermal decomposition, microbial decomposition, molten salt ion exchange, roasting, blast furnace smelting, high-temperature melting and microwave radiation, etc. However, there are some problems in technology and economy, such as single product, excessive energy consumption, serious environmental pollution, overly complicated production process, large amount of tailings residue, too strong alkalinity of potassium fertilizer, insufficient full resource utilization, etc. So far, there has been no large-scale industrial production. It is urgent to develop a universal production method and equipment for large-scale continuous high-pressure hydrothermal production of potassium feldspar to solve the problem of full resource utilization of potassium feldspar resources. 3. Summary of the invention

[0005] The invention aims to overcome the shortcomings of the existing potassium feldspar preparation technology for potassium fertilizer, and to invent a production method for potassium feldspar continuous high-pressure hydrothermal preparation of potassium humate fertilizer. The invention comprises the following steps: preparing alkaline slurry by wet grinding a KOH solution and potassium feldspar, strengthening hydrothermal reaction of the alkaline slurry in an electromagnetic pipeline reactor and a tower delayed reactor, performing steam heat recovery and slurry dilution flocculation and pressure filtration after hydrothermal reaction slurry is separated by flash evaporation, mixing filter residue with humic acid for modification and granulation to produce long-acting slow-release potassium fertilizer, returning the KOH solution obtained by causticizing reaction of filtrate with lime to wet pulping, and mixing calcium silicate with humic acid for modification and granulation production, thereby solving the defects of the original potassium feldspar hydrothermal method for preparing potassium fertilizer, such as low potassium extraction rate, excessive alkalinity of potassium fertilizer products, excessive energy consumption, serious environmental pollution, and failure to effectively utilize tailings residues, and realizing large-scale clean and efficient full-resource fertilizer utilization of potassium feldspar resources.

[0006] The technical solution of the present invention:

[0007] The production method of potassium feldspar continuous high-pressure hydrothermal production of potassium humate fertilizer comprises the following steps: (1) wet grinding pulping process: first, KOH solution and crushed potassium feldspar are added to a wet mill at a weight ratio of 1.5-5:1 and finely ground to produce alkaline ore pulp, wherein the concentration of the KOH solution is 25wt%-45wt%, and the pulping temperature is less than 80°C; (2) hydrothermal reaction process: the alkaline slurry obtained in the previous step is pressurized by a high-pressure pump and then sent to an electromagnetic pipeline reactor for hydrothermal reaction, wherein the flow rate in the tube is 1-5 m / s, the reaction temperature is 200-350°C, the pressure is the saturated pressure at the reaction temperature, and the reaction time is 1-900 seconds, and then the slurry is sent to a tower delay reactor to extend the reaction time for 30-240 minutes to further strengthen the hydrothermal reaction, and a hydrothermal reaction slurry containing a potassium extraction rate of 95%-99.9% is obtained from the bottom of the tower delay reactor; (3) flash evaporation and pressure filtration process: the hydrothermal reaction slurry is passed into a pressure-reducing flash evaporation tower Flash separation, the pressure at the top of the flash tower is normal pressure-30KPa, the high-temperature steam at the top of the tower is used to preheat the air and then obtain cooling water, the slurry at the bottom of the tower is diluted with cooling water and then filtered to obtain alkaline potassium aluminosilicate residue and calcium silicate filtrate; (4) Humic acid modified potash fertilizer preparation process: the alkaline potassium aluminosilicate residue is mixed with humic acid in a weight ratio of 1:0.1-0.3 to modify and granulate to produce a neutral long-acting slow-release potash fertilizer, and the humic acid coating is obtained after hot air heating and drying. Long-acting slow-release potassium fertilizer product; (5) Preparation process of causticizing and humic acid-modified calcium silicate fertilizer: alkaline calcium silicate filtrate is reacted with lime in a potassium to calcium molar ratio of 2:1-1.2 to obtain a KOH solution which is returned to the wet pulping process for recycling; alkaline calcium silicate and humic acid are mixed and modified in a weight ratio of 1:0.1-0.3 to produce a neutral long-acting slow-release calcium silicate fertilizer; and the humic acid-coated long-acting slow-release calcium silicate fertilizer product is obtained by heating and drying with hot air.

[0008] Among them, the electromagnetic heating tubular reactor is a tubular reactor in which, under the action of the electromagnetic heating controller, high-frequency alternating current generates an alternating magnetic field through the coil, and the tubular reactor wall and the internal self-mixing strengthening internal components generate eddy current self-heating, thereby achieving uniform heating, rapid temperature rise and hydrothermal reaction of the high-pressure alkaline slurry; the self-mixing strengthening internal components are regular packing type, X-cross plate type or spiral plate type.

[0009] The tower delayed reactor has a height-to-diameter ratio of 3-30:1, and has filler components, grid self-mixing components or an empty tower inside.

[0010] The flash tower is set to 1-6 levels, and the heat exchanger for flash high-temperature steam cooling is a fire-tube heat exchanger that is easy to clear.

[0011] The humic acid used in the humic acid coated long-acting slow-release potash fertilizer and the humic acid coated long-acting slow-release silicon-calcium fertilizer is a mixture of one or more of biological humic acid, mineral humic acid, molasses waste liquid or monosodium glutamate waste liquid concentrate.

[0012] The potassium aluminosilicate filter residue reacts with biological fulvic acid at a carboxyl to carboxyl molar ratio of 1-3:1 and a temperature of 15-90°C to generate water-soluble potassium fulvic acid and insoluble aluminum silicate.

[0013] The present invention will be described in detail with reference to embodiments. 4. Description of the drawings

[0014] Attached Figure 1 It is a schematic diagram of the present invention.

[0015] Attached Figure 1 The following is a description of the drawings:

[0016] 1. Crusher 2. Wet grinder 3. High-pressure feed pump 4. Electromagnetic heating tubular reactor 5. Electromagnetic heating regulator 6. Tower delayed reactor 7. Flash tower 8. Heat exchanger 9. Flocculation adding tank 10. Filter press 1 11. Mixing and modification granulator 1 12. Dryer 1 13. Causticizing reactor 14. Filter press 2 15. Mixing and modification granulator 2 16. Dryer 2A, flocculant inlet B, lime inlet C, cold air inlet D, humic acid coated long-acting slow-release potash fertilizer E, humic acid coated long-acting slow-release silicon-calcium fertilizer outlet The process features of the present invention are described in detail below in conjunction with the drawings and embodiments. 5. Specific implementation methods

[0017] Embodiment, the production method of potassium feldspar continuous high-pressure hydrothermal production of potassium humate fertilizer, comprising the following steps: (1) wet grinding pulping process: potassium feldspar crushed by a crusher (1) and KOH solution are added to a wet grinder (2) in a weight ratio of 1:1.5-5 to produce alkaline ore pulp, the concentration of KOH solution is 25wt%-45wt%, and the pulping temperature is less than 80°C; (2) hydrothermal reaction process: the alkaline slurry obtained in the previous step is pressurized by a high-pressure pump (3) and then sent to an electromagnetic pipeline reactor (4), and the electromagnetic pipeline reactor (4) is heated under the action of an electromagnetic heating controller (5). The wall and the internal components generate electric eddy currents for uniform heating and hydrothermal reaction, wherein the flow rate in the tube is 1-5 m / s, the reaction temperature is 200-350°C, the pressure is the saturated pressure at the reaction temperature, and the reaction time is 1-900 seconds. Then, the reaction mixture enters the tower delay reactor (6) to extend the reaction time by 30-240 minutes to further strengthen the hydrothermal reaction. A hydrothermal reaction slurry containing a potassium extraction rate of 95%-99.9% is obtained from the bottom of the tower delay reactor (6); (3) flash evaporation and pressure filtration step: the hydrothermal reaction slurry is passed into a pressure-reducing flash tower (7) for flash separation, and the top pressure of the flash tower (7) is 1.5-2.0. The pressure is normal pressure - 30KPa, and the high-temperature steam obtained at the top of the tower is passed through a heat exchanger (8) to preheat the air to obtain cooling water. The cooling water is added to a tank (9) after flocculation and then added to the slurry from the bottom of the tower for dilution and flocculation, and then filtered by a filter press 1 (10) to obtain alkaline potassium aluminosilicate residue and calcium silicate filtrate; (4) Humic acid modified potash fertilizer preparation process: the alkaline potassium aluminosilicate residue and humic acid are mixed and modified in a mixing and modification granulator 1 (11) at a weight ratio of 1:0.1-0.3 for granulation, and the humic acid coated potassium aluminosilicate is dried by hot air in a dryer 1 (12) to produce neutral potassium silicate. Humic acid coated long-acting slow-release potassium fertilizer product; (5) causticizing and humic acid modified silicon calcium fertilizer preparation process: alkaline calcium silicate filtrate and lime are subjected to causticizing reaction in a causticizer (13) at a potassium to calcium molar ratio of 2:1-1.2, and the KOH solution is obtained by a filter press 2 (14) and returned to the wet pulping process for recycling, and alkaline calcium silicate and humic acid are mixed and modified and granulated in a mixing and modification granulator 2 (15) at a weight ratio of 1:0.1-0.3, and the humic acid coated calcium aluminate is dried by hot air in a dryer 1 (12) to produce a neutral humic acid coated long-acting slow-release silicon calcium fertilizer product;

[0018] The electromagnetic heating tubular reactor (4) is a tubular reactor in which, under the action of the electromagnetic heating controller (5), high-frequency alternating current generates an alternating magnetic field through the coil, and the tubular reactor wall and the internal self-mixing strengthening internal components generate eddy current self-heating, thereby achieving uniform heating, rapid temperature rise and hydrothermal reaction of the high-pressure alkaline slurry; the self-mixing strengthening internal components are regular packing type, X-cross plate type or spiral plate type.

[0019] The tower delayed reactor (6) has a height-to-diameter ratio of 3-30:1, and has a filler component, a grid self-mixing component or an empty tower inside.

[0020] The flash tower (7) is set to 1-6 stages, and the heat exchanger (8) for flash high-temperature steam cooling is a fire-tube heat exchanger that is easy to clear.

[0021] The humic acid used in the humic acid coated long-acting slow-release potash fertilizer and the humic acid coated long-acting slow-release silicon-calcium fertilizer is a mixture of one or more of biological humic acid, mineral humic acid, molasses waste liquid or monosodium glutamate waste liquid concentrate.

[0022] The potassium aluminosilicate filter residue reacts with biological fulvic acid at a carboxyl to potassium molar ratio of 1-3:1 and a temperature of 15-90°C to generate water-soluble potassium fulvic acid and insoluble aluminum silicate.

[0023] The specific reaction conditions and experimental results are as follows:

[0024] (1) A 30 wt% KOH solution and a potassium feldspar less than 6 mm and containing 13% potassium are wet-ground into an alkaline ore slurry with a particle size of ≤60 μm at a weight ratio of 3:1 and a temperature of 45° C., and then subjected to a hydrothermal reaction in an electromagnetic pipeline reactor at a flow rate of 2 m / s and a temperature of 280° C. for 10 seconds, and then delayed for 50 minutes in a tower delay reactor to obtain a hydrothermal reaction slurry with a potassium extraction rate of 98%; the hydrothermal reaction slurry is flash-distilled and separated in a secondary flash tower, and steam is heat-exchanged with air and diluted and filtered, and the obtained potassium aluminosilicate and calcium silicate are respectively mixed, modified, granulated and dried by adding 10% biological brown-black humic acid to obtain a humic acid-coated long-acting slow-release potassium fertilizer product containing 28% potassium and 22% silicon and a humic acid-coated long-acting slow-release silicon-calcium fertilizer product containing 24% silicon, and the KOH solution is circulated, and 10% KOH needs to be supplemented.

[0025] (2) 35wt% KOH solution and potassium feldspar less than 6mm and containing 13% potassium are wet-ground into alkaline ore slurry with a particle size of ≤74μm at a weight ratio of 2.5:1 and a temperature of 60°C, and then subjected to hydrothermal reaction in an electromagnetic pipeline reactor at a flow rate of 3 m / s and a temperature of 290°C for 7 seconds, and then delayed reaction in a tower delay reactor for 60 minutes to obtain a hydrothermal reaction slurry with a potassium extraction rate of 99.5%; the hydrothermal reaction slurry is flash-separated in a secondary flash tower, steam heat-exchanged with air and diluted and filtered, and the obtained potassium aluminosilicate and calcium silicate are respectively mixed by adding 15% of mineral brown-black humic acid, modified, granulated and dried to obtain a humic acid-coated long-acting slow-release potassium fertilizer product containing 27% potassium and 20% silicon and a humic acid-coated long-acting slow-release silicon-calcium fertilizer product containing 24.2% silicon, and the KOH solution is circulated, and 9% KOH needs to be supplemented.

[0026] (3) 35 wt % KOH solution and potassium feldspar less than 6 mm and containing 13 % potassium are wet-ground into alkaline ore slurry with a particle size of ≤74 μm at a temperature of 60° C., and then subjected to hydrothermal reaction in an electromagnetic pipeline reactor at a flow rate of 3 m / s and a temperature of 290° C. for 7 seconds, and then delayed reaction in a tower delay reactor for 60 minutes to obtain a hydrothermal reaction slurry with a potassium extraction rate of 99.5%; the hydrothermal reaction slurry is flash-distilled in a secondary flash tower The obtained calcium silicate is mixed, modified, granulated and dried by adding 15% biological brown-black humic acid to obtain a humic acid-coated long-acting slow-release silicon-calcium fertilizer product containing 24.2% silicon. The KOH solution is circulated and 9% KOH needs to be supplemented. The obtained potassium aluminosilicate is reacted at a temperature of 65°C according to a carboxyl to methanol molar ratio of 2:1 to generate a potassium humate solution and a difficult aluminum silicate precipitate. The potassium humate solution is dried to obtain a potassium humate product containing 30% potassium.

[0027] The production method of preparing humic acid potassium fertilizer by continuous high-pressure hydrothermal method of potassium feldspar provided by the present invention comprises the following steps: in-situ wet grinding activation by KOH and electromagnetic heating pipeline high-pressure hydrothermal desiliconization, flash separation after enhanced hydrothermal desiliconization in a tower-type delayed reactor, separated steam-heated air is used for product drying, and potassium fertilizer and calcium silicon fertilizer desiliconized by alkali hydration are neutralized, modified and granulated by humic acid to obtain universal long-acting slow-controlled fertilizer, the potassium extraction rate of potassium fertilizer prepared by the original potassium feldspar hydrothermal method is increased from 85% to more than 99%, the pH value of the potassium fertilizer product is reduced from 13 to 6-8, the energy consumption of electromagnetic heating is reduced by 30%, there is no pollution of dust and wastewater, and large-scale clean and efficient full-resource fertilizer utilization of potassium feldspar resources is realized.

Claims

1. A production method for preparing potassium humate fertilizer by continuous high-pressure hydrothermal treatment of potassium feldspar, characterized in that The following steps are involved: (1) Wet grinding pulping process: first, KOH solution and crushed potassium feldspar are added to a wet mill in a weight ratio of 1.5-5:1 for fine grinding to prepare alkaline ore pulp, the KOH solution concentration is 25wt%-45wt%, and the pulping temperature is less than 80°C; (2) Hydrothermal reaction process: the alkaline slurry obtained in the previous step is pressurized by a high-pressure pump and sent to an electromagnetic pipeline reactor for hydrothermal reaction, wherein the flow rate in the tube is 1-5 m / s, the reaction temperature is 200-350°C, the pressure is the saturated pressure at the reaction temperature, and the reaction time is 1-900 seconds, and then enters a tower delay reactor to extend the reaction time for 30-240 minutes to further strengthen the hydrothermal reaction, and a hydrothermal reaction slurry with a potassium extraction rate of 95%-99.9% is obtained from the bottom of the tower delay reactor; (3) Flash evaporation and pressure filtration process: the hydrothermal reaction slurry is passed into a pressure-reducing flash tower for flash separation, and the pressure at the top of the flash tower is atmospheric pressure -30KPa, the top of the tower obtains high-temperature steam to preheat the air and then obtains cooling water, the slurry at the bottom of the tower is diluted with cooling water and then filtered to obtain alkaline potassium silicate residue and calcium silicate filtrate; (4) humic acid modified potash fertilizer preparation process: the alkaline potassium silicate residue and humic acid are mixed and modified in a weight ratio of 1:0.1-0.3 to granulate to produce a neutral long-acting slow-release potash fertilizer, and the humic acid coated long-acting slow-release potash fertilizer product is obtained after hot air heating and drying; (5) causticizing and humic acid modified calcium silicate fertilizer preparation process: the alkaline calcium silicate filtrate and lime are causticized in a potassium to calcium molar ratio of 2:1-1.2 to obtain a KOH solution which is returned to the wet pulping process for recycling, the alkaline calcium silicate and humic acid are mixed and modified in a weight ratio of 1:0.1-0.3 to granulate to produce a neutral long-acting slow-release calcium silicate fertilizer, and the humic acid coated long-acting slow-release calcium silicate fertilizer product is obtained after hot air heating and drying.

2. The method for producing potassium humate fertilizer by continuous high-pressure hydrothermal treatment of potassium feldspar according to claim 1, characterized in that The electromagnetic heating tubular reactor is a tubular reactor in which, under the action of an electromagnetic heating controller, high-frequency alternating current passes through a coil to generate an alternating magnetic field, and eddy current self-heating is generated on the tubular reactor wall and the internal self-mixing strengthening internal components. The self-mixing strengthening internal components are regular packing type, X-cross plate type or spiral plate type.

3. The method for producing potassium humate fertilizer by continuous high-pressure hydrothermal treatment of potassium feldspar according to claim 1, characterized in that The tower delayed reactor has a height-to-diameter ratio of 3-30:1, and has filler components, grid self-mixing components or an empty tower inside.

4. The method for producing potassium humate fertilizer by continuous high-pressure hydrothermal treatment of potassium feldspar according to claim 1, characterized in that The flash tower is set to 1-6 stages, and the heat exchanger for flash high-temperature steam cooling is a fire-tube heat exchanger.

5. The method for producing potassium humate fertilizer by continuous high-pressure hydrothermal treatment of potassium feldspar according to claim 1, characterized in that The humic acid used in the humic acid coated long-acting slow-release potash fertilizer and the humic acid coated long-acting slow-release silicon-calcium fertilizer is a mixture of one or more of biological humic acid, mineral humic acid, molasses waste liquid or monosodium glutamate waste liquid concentrate.

6. The method for producing potassium humate fertilizer by continuous high-pressure hydrothermal method of potassium feldspar according to claim 1, characterized in that The potassium aluminosilicate filter residue reacts with biological fulvic acid at a carboxyl to potassium molar ratio of 1-3:1 and a temperature of 15-90°C to generate water-soluble potassium fulvic acid and insoluble aluminum silicate.

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