Large-scale continuous production device for potassium humate potassium fertilizer and full resource utilization of potassium feldspar

Abstract

The large-scale continuous production and full resource utilization plant for potassium feldspar-based humic acid fertilizer includes a wet pulping subsystem, a hydrothermal reaction subsystem, a flash evaporation and filtration subsystem, a humic acid-modified potassium fertilizer preparation subsystem, and a causticization and humic acid-modified silicon-calcium fertilizer preparation subsystem. The wet pulping subsystem is connected to the hydrothermal reaction subsystem via a high-pressure feed pump. The hydrothermal reaction subsystem is connected to the feed inlet of a pressure-reducing flash evaporation tower via the bottom of a tower-type delayed reactor. The flash evaporation and filtration subsystem is connected to the humic acid-modified potassium fertilizer preparation subsystem via the solid phase outlet of filter press A, and to the causticization and humic acid-modified silicon-calcium fertilizer preparation subsystem via the liquid phase outlet of filter press A. The KOH outlet of filter press B in the causticization and humic acid-modified silicon-calcium fertilizer preparation subsystem is connected back to the wet mill of the wet pulping subsystem, forming a large-scale continuous high-pressure hydrothermal production and full resource utilization recycling system for potassium feldspar-based humic acid fertilizer.

Description

1. Technical Field

[0001] This invention provides a production device for large-scale continuous production of potassium humate fertilizer from potassium feldspar and full resource utilization, which relates to the field of fine chemicals. 2. Background Technology

[0002] Potassium is one of the three essential nutrients for crop growth, enhancing crops' resistance to drought, cold, disease, salt, and lodging. It plays a significant role in ensuring stable and high yields, thus almost every crop requires appropriate amounts of potassium fertilizer. As a vast agricultural country, my country faces a huge demand gap for potassium fertilizer. However, due to the extreme scarcity of water-soluble potassium salt resources used as fertilizer—its reserves, converted to K2O, are approximately 450 million tons, accounting for only 2.647% of the world's total—my country, as the world's largest consumer of potassium fertilizer, has an import dependency exceeding 50%.

[0003] However, my country possesses extremely abundant non-water-soluble potassium mineral resources, characterized by wide distribution, high quality, and ease of mining. Among these, potassium feldspar is the most representative, distributed in 23 provinces and regions including Inner Mongolia, Anhui, Heilongjiang, Sichuan, and Xinjiang, with estimated reserves exceeding 20 billion tons. Because potassium feldspar has a three-dimensional framework structure formed by Si-Al-O tetrahedra, it is chemically extremely stable and almost undecomposed by acids and bases other than concentrated sulfuric acid and hydrofluoric acid under normal temperature and pressure. Therefore, efficiently decomposing potassium feldspar and converting its non-water-soluble potassium into water-soluble potassium compounds is crucial for potassium salt extraction.

[0004] More than ten processes have been developed both domestically and internationally for producing potash fertilizer from potassium feldspar, including low-temperature decomposition, hydrothermal decomposition, microbial decomposition, molten salt ion exchange, roasting, blast furnace smelting, high-temperature melting, and microwave radiation. However, these methods all have some technical and economic drawbacks, such as limited product variety, excessive energy consumption, severe environmental pollution, overly complex production processes, large amounts of tailings residue, excessively alkaline potash fertilizer, and insufficient utilization of all resources. To date, large-scale industrial production has not been observed. There is an urgent need to develop a production method and equipment for large-scale, continuous, high-pressure hydrothermal production of universally applicable modified potash fertilizer from potassium feldspar, in order to solve the problem of full utilization of potassium feldspar resources. 3. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing potassium feldspar-based potassium fertilizer production technologies by developing a large-scale, continuous, high-pressure hydrothermal production device for humic acid potassium fertilizer and its full resource utilization. The device involves wet grinding potassium feldspar with KOH solution to produce an alkaline slurry. This alkaline slurry undergoes enhanced hydrothermal reaction in an electromagnetic pipeline reactor and a tower-type delayed reactor. The hydrothermal slurry is separated by flash evaporation, followed by steam heat recovery, slurry dilution, flocculation, and pressure filtration. The filter residue is mixed with humic acid for modification and granulation to produce long-acting slow-release potassium fertilizer. The KOH solution from the filtrate, obtained through a causticization reaction with lime, is returned to the wet pulping process. Calcium silicate is then mixed with humic acid for modification and granulation to produce potassium fertilizer. This invention overcomes the shortcomings of traditional potassium feldspar hydrothermal potassium fertilizer production methods, such as low potassium extraction rate, excessively alkaline potassium fertilizer products, excessive energy consumption, severe environmental pollution, and ineffective utilization of tailings residue. It achieves large-scale, clean, efficient, and full resource utilization of potassium feldspar resources for fertilizer production.

[0006] The technical solution of this invention:

[0007] This production unit for the large-scale, continuous, high-pressure hydrothermal extraction of potassium feldspar into potassium humate fertilizer and its full resource utilization comprises: a crusher connected to a wet grinding unit to form a wet pulping subsystem; a KOH solution to potassium feldspar weight ratio of 1.5-5:1; a KOH solution concentration of 25wt%-45wt%; and a pulping temperature below 80℃; an electromagnetic pipeline reactor connected to a tower-type delayed reactor to form a hydrothermal reaction subsystem; a flow velocity of 1-5 m / s within the pipeline; a reaction temperature of 200-350℃; a pressure equal to the saturation pressure at that reaction temperature; a reaction time of 1-900 seconds; a delayed reaction time of 30-240 minutes; and a potassium extraction rate of 95%-99.9%; a flash evaporation tower with a heat exchanger at the top and a filter press at the bottom, and a condensate outlet connected to a flocculation inlet tank before filter press A to form a flash evaporation and filtration subsystem; and a flash evaporation tower top pressure of atmospheric pressure -30 kPa; and a mixing and modifying granulator connected to a dryer to form a humic acid-modified potassium fertilizer preparation subsystem. The weight ratio of alkaline potassium aluminosilicate filter residue to humic acid is 1:0.1-0.3; the causticization reactor is connected to a filter press B and a mixing and modifying granulator, and then connected to a dryer 2 to form a causticization and humic acid modified calcium silicate fertilizer preparation subsystem. The molar ratio of potassium to calcium in the alkaline calcium silicate filtrate is 2:1-1.2; the wet pulping subsystem is connected to the hydrothermal reaction subsystem via a high-pressure feed pump, and the hydrothermal reaction subsystem is fed through the bottom of a tower-type delayed reactor and a pressure-reducing flash evaporator. The flash evaporation and filtration subsystem is connected to the humic acid modified potassium fertilizer preparation subsystem via the solid phase outlet of filter press A, and to the causticization and humic acid modified silicon-calcium fertilizer preparation subsystem via the liquid phase outlet of filter press A. The KOH outlet of filter press B of the causticization and humic acid modified silicon-calcium fertilizer preparation subsystem is then connected back to the wet mill of the wet pulping subsystem, forming a circular processing system for large-scale continuous high-pressure hydrothermal production of potassium feldspar potassium humate fertilizer and full resource utilization.

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

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

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

[0011] The features of the present invention will be described in detail through embodiments. 4. Description of the attached drawings

[0012] Appendix Figure 1 This is a schematic diagram of the device of the present invention.

[0013] Appendix Figure 1 The diagram is explained as follows:

[0014] 1. Crusher 2. Wet mill 3. High-pressure feed pump 4. Electromagnetic heating tubular reactor 5. Electromagnetic heating controller 6. Tower-type delayed reactor 7. Flash evaporator 8. Heat exchanger 9. Flocculation inlet tank 10. Filter press A 11. Mixing and modifying granulator 1 12. Dryer 1 13. Causticizing reactor 14. Filter press B 15. Mixing and modifying granulator 2 16. Dryer 2 A. Flocculant inlet B. Lime inlet C. Cold air inlet D. Humic acid-coated long-acting slow-release potassium fertilizer E. Humic acid-coated long-acting slow-release silicon-calcium fertilizer outlet

[0015] The process features of the present invention will be described in detail below with reference to the accompanying drawings and embodiments. 5. Detailed Implementation

[0016] Example

[0017] A large-scale continuous production facility for potassium feldspar to produce potassium humate fertilizer and its full resource utilization consists of a crusher (1) connected to a wet mill (2) to form a wet pulping subsystem. The weight ratio of KOH solution to potassium feldspar is 1.5-5:1, the concentration of KOH solution is 25wt%-45wt%, and the pulping temperature is less than 80℃. An electromagnetic pipeline reactor (4) is connected to a tower-type delayed reactor (6) to form a hydrothermal reaction subsystem. The flow velocity inside the pipe is 1-5 m / s, the reaction temperature is 200-350℃, and the pressure is [value missing] at the reaction temperature. The saturated pressure and reaction time are 1-900 seconds, the delayed reaction time is 30-240 minutes, and the potassium extraction rate is 95%-99.9%. The top of the pressure-reducing flash evaporator (7) is connected to a heat exchanger, the bottom of the evaporator is connected to a filter press A (10), and the condensate outlet of the heat exchanger (8) is connected to the flocculation addition tank before the filter press A (10) to form a flash evaporation and filtration subsystem. The top pressure of the flash evaporator (7) is atmospheric pressure -30KPa. The mixing and modifying granulator (11) is connected to the dryer 1 (12) to form a humic acid modified potassium fertilizer preparation subsystem. Alkaline silicon aluminum The weight ratio of potassium silicate filter residue to humic acid is 1:0.1-0.3; the causticization reactor (13) is connected to the mixing and modifying granulator (15) via the filter press B (14) and then connected to the dryer 2 (16) to form a causticization and humic acid modified calcium silicate fertilizer preparation subsystem. The molar ratio of potassium and calcium in the alkaline calcium silicate filtrate to lime is 2:1-1.2; the wet pulping subsystem is connected to the hydrothermal reaction subsystem via the high-pressure feed pump (3). The hydrothermal reaction subsystem is connected to the bottom of the tower-type delayed reactor (6) and the pressure-reducing flash evaporator (7). The feed inlet is connected to the flash evaporation filter press subsystem, which is connected to the humic acid modified potassium fertilizer preparation subsystem through the solid phase outlet of filter press A (10). The flash evaporation filter press subsystem is connected to the causticization and humic acid modified silicon-calcium fertilizer preparation subsystem through the liquid phase outlet of filter press A (10). The KOH outlet of filter press B (14) of the causticization and humic acid modified silicon-calcium fertilizer preparation subsystem is connected back to the wet mill (2) of the wet pulping subsystem, forming a large-scale continuous high-pressure hydrothermal production of humic acid potassium fertilizer from potassium feldspar and a circular processing system for full resource utilization.

[0018] Among them, the electromagnetic heating tubular reactor (4) generates eddy current self-heating in the tubular reactor cylinder wall and the internal self-mixing strengthening internal components when the high-frequency alternating current generates an alternating magnetic field through the coil under the action of the electromagnetic heating controller (5), thereby realizing uniform heating, rapid temperature rise and hydrothermal reaction of 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-type delayed reactor (6) has a height-to-diameter ratio of 3-30:1, and its interior consists of packed components, grid self-mixing components, or empty towers.

[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 clean.

[0021] The specific reaction conditions and experimental results are as follows:

[0022] (1) 30wt% KOH solution and potassium feldspar with a particle size of less than 6mm and a potassium content of 13% were wet-ground into an alkaline slurry with a particle size of ≤60μm at a weight ratio of 3:1 and a temperature of 45℃. The slurry was then subjected to a hydrothermal reaction for 10 seconds at a flow rate of 2 m / s and a temperature of 280℃ in an electromagnetic pipeline reactor. After that, the reaction was delayed for 50 minutes in a tower-type delayed reactor to obtain a hydrothermal reaction slurry with a potassium extraction rate of 98%. The hydrothermal reaction slurry was flash-separated in a two-stage flash tower, and the steam was used to heat the air and dilute the filtrate for filtration. The obtained potassium aluminosilicate and calcium silicate were mixed, modified, granulated and dried by adding 10% bio-brown humic acid to obtain a humic acid-coated long-acting slow-release potassium fertilizer product with a potassium content of 28% and a silicon content of 22% and a humic acid-coated long-acting slow-release silicon-calcium fertilizer product with a silicon content of 24%. The KOH solution obtained by causticization was recycled and 10% KOH was added.

[0023] (2) 35wt% KOH solution and potassium feldspar (less than 6mm, containing 13% potassium) at a weight ratio of 2.5:1 and a temperature of 60℃ are wet-ground into an alkaline slurry with a particle size ≤74μm. The slurry is then subjected to a hydrothermal reaction for 7 seconds in an electromagnetic pipeline reactor at a flow rate of 3 m / s and a temperature of 290℃. After that, the reaction is delayed for 60 minutes in a tower-type delayed reactor to obtain a hydrothermal reaction slurry with a potassium extraction rate of 99.5%. The hydrothermal reaction slurry is then subjected to flash separation, steam heat exchange for air and dilution filtration in a two-stage flash tower, and causticized and filtered again. The obtained potassium aluminosilicate and calcium silicate are mixed, modified, granulated and dried by adding 15% mineral-derived brown-black humic acid 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. The KOH solution obtained by causticization is recycled and needs to be replenished with 9% KOH.

[0024] (3) A 35wt% KOH solution and potassium feldspar (less than 6mm, containing 13% potassium) at a weight ratio of 2.5:1 and a temperature of 60℃ were wet-ground into an alkaline slurry with a particle size ≤74μm. This slurry was then subjected to a 7-second hydrothermal reaction in an electromagnetic pipeline reactor at a flow rate of 3 m / s and a temperature of 290℃, followed by a 60-minute extended reaction in a tower-type delayed reactor to obtain a hydrothermal reaction slurry with a potassium extraction rate of 99.5%. The hydrothermal reaction slurry was then flash-separated in a two-stage flash evaporation tower, and the steam heat exchanger was used for further processing. The process involves gas dilution filtration, causticization and re-filtration of the filtrate, and the addition of 15% bio-brown humic acid to obtain calcium silicate. This mixture is then modified, granulated, and dried to produce a humic acid-coated, long-lasting, slow-release calcium silicate fertilizer product containing 24.2% silicon. The KOH solution obtained from causticization is recycled, requiring the addition of 9% KOH. Potassium aluminosilicate is then reacted at a carboxyl to potassium molar ratio of 2:1 at 65°C to produce a potassium fulvate solution and a sparingly soluble aluminum silicate precipitate. The potassium fulvate solution is dried to obtain a potassium fulvate product containing 30% potassium.

[0025] The large-scale continuous production and full-resource utilization device for potassium feldspar to produce potassium humate fertilizer provided by this invention utilizes in-situ wet grinding activation with KOH, electromagnetic heating in a pipeline high-pressure hydrothermal desilication process, enhanced hydrothermal desilication in a tower-type delayed reactor, and flash separation. The separated steam is used to heat air for product drying. The potassium fertilizer and calcium-silicon fertilizer obtained by alkali-hydrate desilication are neutralized and modified by humic acid and granulated to obtain a universally applicable long-acting slow-release fertilizer. This method increases the potassium extraction rate from 85% to over 99% and reduces the pH value of the potassium fertilizer product from 13 to 6-8, while reducing electromagnetic heating energy consumption by 30%. It also eliminates dust and wastewater pollution, achieving large-scale, clean, efficient, and full-resource utilization of potassium feldspar resources as fertilizer.

Claims

1. A production device for large-scale continuous high-pressure hydrothermal preparation of potassium humate potassium fertilizer and full resource utilization of potassium feldspar, characterized in that The crusher is connected with a wet grinding mechanism to form a wet pulping subsystem, the weight ratio of KOH solution to potassium feldspar is 1.5-5:1, the concentration of KOH solution is 25wt%-45wt%, and the pulping temperature is less than 80℃; the electromagnetic pipeline reactor is connected with a tower type delay reactor to form a hydrothermal reaction subsystem, the flow rate in the pipeline is 1-5m / s, the reaction temperature is 200-350℃, the pressure is the saturation pressure at the reaction temperature, the reaction time is 1-900s, the delay reaction time is 30-240min, and the potassium extraction rate is 95%-99.9%; the top of the flash evaporation tower is connected with a heat exchanger, the bottom is connected with a filter press, and the condensate outlet of the heat exchanger is connected with a flocculation addition tank before the filter press A to form a flash evaporation and filter pressing subsystem, the top pressure of the flash evaporation tower is normal pressure-30KPa; the mixed modified granulator is connected with a dryer 1 to form a humic acid modified potassium fertilizer preparation subsystem, the weight ratio of the alkaline potassium silicate and aluminate filter residue to humic acid is 1:0.1-0.3; the causticization reactor is connected with a mixed modified granulator and then connected with a dryer 2 to form a causticization and humic acid modified silicon calcium fertilizer preparation subsystem, the molar ratio of potassium and calcium in the alkaline potassium silicate and aluminate filtrate to lime is 2:1-1.2; the wet pulping subsystem is connected with the hydrothermal reaction subsystem through a high-pressure feed pump, the hydrothermal reaction subsystem is connected with the flash evaporation tower through the tower type delay reactor at the bottom, the flash evaporation and filter pressing subsystem is connected with the humic acid modified potassium fertilizer preparation subsystem through the solid phase outlet of the filter press A, the flash evaporation and filter pressing subsystem is connected with the causticization and humic acid modified silicon calcium fertilizer preparation subsystem through the liquid phase outlet of the filter press A, and the KOH outlet of the filter press B of the causticization and humic acid modified silicon calcium fertilizer preparation subsystem is connected back to the wet grinder of the wet pulping subsystem, forming a large-scale continuous high-pressure hydrothermal humic acid potassium fertilizer preparation and full resource utilization cyclic treatment system.

2. The production device for large-scale continuous high-pressure hydrothermal preparation of potassium humic acid potassium fertilizer and full resource utilization according to claim 1, characterized in that The electromagnetic heating tube reactor is heated by the self-mixing reinforced internal components in the tube wall and the inside of the tube reactor under the action of the electromagnetic heating regulator when the high-frequency alternating current passes through the coil to generate an alternating magnetic field, realizing uniform heating, rapid heating and hydrothermal reaction of the high-pressure alkaline ore slurry; the self-mixing reinforced internal components are regular packing type, X cross sheet type or spiral sheet type.

3. The production device for large-scale continuous high-pressure hydrothermal preparation of potassium humic acid potassium fertilizer and full resource utilization according to claim 1, characterized in that The tower type delay reactor has a height-diameter ratio of 3-30:1, and the inside is filled with packing components, grid self-mixing components or empty tower.

4. The production device for large-scale continuous high-pressure hydrothermal preparation of potassium humic acid potassium fertilizer and full resource utilization according to claim 1, characterized in that The flash evaporation tower is set to 1-6 stages, and the heat exchanger for flash evaporation high-temperature steam cooling is a fire tube heat exchanger for easy blockage.

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