CN113072409A - Low tower preparation method of small particle calcium fertilizer containing nitrogen and calcium oxide - Google Patents
Low tower preparation method of small particle calcium fertilizer containing nitrogen and calcium oxide Download PDFInfo
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- CN113072409A CN113072409A CN202110295958.8A CN202110295958A CN113072409A CN 113072409 A CN113072409 A CN 113072409A CN 202110295958 A CN202110295958 A CN 202110295958A CN 113072409 A CN113072409 A CN 113072409A
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- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
- C05G3/00—Mixtures of one or more fertilisers with additives not having a specially fertilising activity
- C05G3/30—Anti-agglomerating additives; Anti-solidifying additives
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- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05C—NITROGENOUS FERTILISERS
- C05C1/00—Ammonium nitrate fertilisers
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- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
- C05G5/00—Fertilisers characterised by their form
- C05G5/10—Solid or semi-solid fertilisers, e.g. powders
- C05G5/12—Granules or flakes
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- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
- C05G5/00—Fertilisers characterised by their form
- C05G5/30—Layered or coated, e.g. dust-preventing coatings
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Abstract
The invention discloses a low-tower preparation method of a small-particle calcium fertilizer containing nitrogen and calcium oxide, wherein the small-particle calcium fertilizer is a calcium ammonium nitrate fertilizer, and the calcium ammonium nitrate fertilizer comprises the following components in percentage by mass: 12-30% of nitrogen and 15-30% of calcium oxide. The calcium ammonium nitrate fertilizer is prepared into slurry, and is emulsified and granulated to obtain a small-particle product within the range of 0.5-2.5 mm. The atomizing centrifugal granulator is used in the granulation link, the height of a granulation tower can be reduced to about 30 meters from more than 100 meters, and the slurry is granulated by the atomizing centrifugal granulator to obtain small particles by controlling different technical indexes such as slurry temperature, granulator specification, granulator discharging mode, granulator rotating speed and the like. And cooling, screening and grading the small particle products, coating and enveloping the small particle products, and packaging to obtain finished products. The special structure of the atomizing centrifugal granulator designed by the invention can not cause the blockage phenomenon of the granulator, so that the production operation is easier to control than a high tower granulator, and the production continuity is stronger.
Description
Technical Field
The invention belongs to the technical field of fertilizer preparation, and mainly relates to a low-tower preparation method of a small-particle calcium fertilizer containing nitrogen and calcium oxide.
Background
Fertilizers have been continuously innovated and developed as one of the essential factors for plant growth. The calcium ammonium nitrate fertilizer is white round particles, is 100 percent soluble in water, is a novel high-efficiency compound fertilizer containing nitrogen and quick-acting calcium, has the characteristics of quick fertilizer effect and quick nitrogen supplement, is added with calcium, has more comprehensive nutrients than ammonium nitrate, and can be directly absorbed by plants. The calcium ammonium nitrate belongs to a neutral fertilizer, has small physiological acidity and has an improvement effect on acid soil. After the fertilizer is applied to soil, the pH value is low, the soil is not hardened, and the soil can be loosened. Meanwhile, the concentration of active aluminum can be reduced, the fixation of active phosphorus is reduced, and the provided water-soluble calcium can improve the resistance of plants to diseases.
The preparation process of the fertilizer plays an indispensable role from simple mixed fertilizer to extrusion granulation, disc granulation, drum granulation, slurry spraying granulation, high tower granulation and the like. Particularly, a high tower granulation technology represented by Shenzhen Bombay plays a very important role as a leader and a advocate in the development of the fertilizer industry in China in the last twenty years.
The high tower fertilizer has the following advantages:
1. the slurry is melted, sprayed and granulated, the moisture of the finished product is low, and the drying is not needed, so that the drying process is omitted, the floor area of a production workshop is smaller, and the production cost is low.
2. The slurry automatically condenses into spherical fertilizer particles with smooth surfaces under the action of surface tension of liquid drops in the falling process of the slurry in the tower, and the particles have high strength and are not easy to agglomerate.
3. The high tower granulation does not need to add fillers such as a binder and the like, and the fertilizer has high purity, high water solubility and stronger fertilizer efficiency.
4. Each particle has a melting hole, and the dissolution speed is high.
However, high tower granulation also has a number of problems:
1. the high tower granulation production line has high investment: the construction cost of a cement tower with the length of about 110 meters is about more than 1500 ten thousand, and the equipment investment is close to 2000 ten thousand yuan;
2. the height of the granulation tower is more than 100 meters, the air inflow is large, the dust treatment difficulty is large, and the environmental pollution diffusion radius is large;
3. the transportation of the raw materials from the ground to the tower top has high operation cost;
4. once the inner wall of the higher tower body is stuck, the tower wall is very difficult to clean, and unsafe factors are obviously increased.
At present, most of compound fertilizer particles in the market are products with the particle size of 2-4.75 mm, and with the development of various fertilization technologies, formulation processes and fertilization facilities, the market demand for the compound fertilizer with the micro particles of 0.5-2.5mm is gradually increased. However, no special production process is available for producing such products, for example, the production is carried out by adopting the high tower granulation technology in the patents of 'method and system for producing compound fertilizer by high tower granulation and compound fertilizer-CN 108707000A', 'method for producing urea-based compound fertilizer by high tower granulation-CN 102584395A', 'method for producing granular compound fertilizer by high tower granulation and equipment-CN 1213001C', and small granular materials can be produced by reducing the aperture of a screen in a high tower granulator from 2-4mm to 1-2 mm, but the following problems can be caused: impurities such as infusible matters and the like exceeding the size of the sieve mesh in the raw material can block the sieve mesh or gather in the sieve mesh after the aperture of the sieve mesh is reduced, so that the cleaning is frequent, the infusible matters and the impurities comprise hard particles in the raw material, rust impurities in equipment and infusible matters generated in the pulping process, and various infusible matters can not be completely removed in the production; and secondly, the height of the tower required by the production of the compound fertilizer particles of 0.5-2.5mm is far lower than that of the tower required by the production of the compound fertilizer particles of 2-4.75 mm and is about 1/8-1/3, and the production of the product by using the original high tower system is extremely waste.
Disclosure of Invention
The invention aims to solve the defects in the high tower granulation process technology and provides a low tower granulation preparation method of a small granular calcium fertilizer containing nitrogen and calcium oxide and the small granular calcium fertilizer prepared by the method.
The invention uses the slurry preparation link of high tower granulation as reference for low tower granulation, but uses the atomizing granulator to replace the differential granulator of high tower technology in the granulation link, and reduces the height of the granulation tower from more than 100 meters to about 30 meters. Through controlling technical indexes such as different slurry temperatures, granulator specifications, granulator discharging modes, granulator rotating speed and the like, the slurry is granulated by an atomizing granulator to generate small-particle products within the range of 0.5-2.5 mm. And cooling, screening and grading the small particle products, coating and enveloping the small particle products, and packaging to obtain finished products.
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
a low tower preparation method of a small particle calcium fertilizer containing nitrogen and calcium oxide comprises the following steps:
s1, melting a calcium ammonium nitrate fertilizer into slurry, and heating the slurry to 140-160 ℃ for later use; the viscosity of the slurry is 1000-5000 centipoises;
s2, emulsifying the slurry, and then granulating in a granulator; the granulator is a low-tower atomization centrifugal granulator, the centrifugal granulator comprises a granulating disc, and the granulating disc comprises a feed inlet, an upper granulating disc cover, a flow deflector and a lower granulating disc cover which are sequentially connected from top to bottom; the size of a slurry outlet formed by the flow deflector is 6-40 mm; after the slurry flows into the granulating disc through the feed inlet, the granulating disc rotates at a high speed, so that the slurry moves towards the edge of the granulating disc along the flow deflector under the action of centrifugal force, the slurry gradually extends into a film in the moving process, and when the slurry moves to the most edge of the granulating disc, the slurry is changed into fine liquid drops from the film under the action of centrifugal force and is thrown out of the granulating disc;
s3, screening the granular materials obtained after granulation: the granular materials with the grain diameter of 0.5-2.5mm are qualified materials; returning the granular materials with the grain diameter of more than 2.5mm and the grain diameter of less than 0.5mm together for re-mixing and granulation;
s4, cooling the qualified materials, performing anti-hardening treatment, then continuously screening, grouping, packaging and warehousing; the water content of the obtained small-particle calcium fertilizer is 0.4-1.3%.
Preferably, the low-tower preparation method of the small-particle calcium fertilizer containing nitrogen and calcium oxide is characterized in that the small-particle calcium fertilizer is a calcium ammonium nitrate fertilizer, and the calcium ammonium nitrate fertilizer comprises the following components in percentage by mass: 12-30% of nitrogen and 15-30% of calcium oxide;
preferably, the low-tower preparation method of the small-particle calcium fertilizer comprises the following steps:
s1, adding a calcium ammonium nitrate fertilizer into a first reaction kettle to be melted into slurry, and heating the slurry to 140-160 ℃ for later use;
s2, opening a discharge valve of the first reaction kettle to enable all the slurry to enter a second reaction kettle, and keeping the temperature of the slurry in the second reaction kettle at 140-160 ℃ for later use;
s3, discharging the material from the second reaction kettle, emulsifying the prepared slurry by an emulsifying machine, and then feeding the emulsified slurry into a granulator for granulation; the granulator is a low-tower atomization centrifugal granulator, the centrifugal granulator comprises a granulating disc, and the granulating disc comprises a feed inlet, an upper granulating disc cover, a flow deflector and a lower granulating disc cover which are sequentially connected from top to bottom; the size of a slurry outlet formed by the flow deflector is 6-40 mm; after the slurry flows into the granulating disc through the feed inlet, the granulating disc rotates at a high speed, so that the slurry moves towards the edge of the granulating disc along the flow deflector under the action of centrifugal force, the slurry gradually extends into a film in the moving process, and when the slurry moves to the most edge of the granulating disc, the slurry is changed into fine liquid drops from the film under the action of centrifugal force and is thrown out of the granulating disc;
s4, screening the granular materials obtained after granulation: the granular materials with the grain diameter of 0.5-2.5mm are qualified materials; crushing the granular materials with the particle size of more than 2.5mm, feeding the crushed granular materials and the granular materials with the particle size of less than 0.5mm into a material returning preheating system as returning materials, preheating the returning materials to 140-160 ℃, and slowly feeding the returning materials into a second reaction kettle for re-mixing and granulation;
and S5, cooling the qualified materials, performing anti-hardening treatment, then continuously screening and grouping, and respectively packaging and warehousing.
The invention optimizes the particle size of the calcium ammonium nitrate particles, innovatively develops a low-tower granulation method, and greatly reduces the production cost.
In the preparation method, the outlet size of the mixed slurry of the granulating disc is set to be 6-40 mm, namely, the slurry impurities smaller than the outlet size can be thrown out of the granulating disc under the action of centrifugal force, and the impurities in the slurry can not exceed 5mm generally, so that compared with high-tower granulation, the centrifugal granulation can greatly reduce the probability of material blockage and reduce the shutdown phenomenon caused by material blockage. As the compound fertilizer particles with the particle size of 0.5-2.5mm are smaller, the specific surface area is increased under the same weight compared with the compound fertilizer particles with the particle size of 2-4mm, namely the contact area with air is more in the falling process of the particles under the condition of the same weight, the falling height required by the particles with the particle size of 0.5-2.5mm is smaller and is about 1/5-1/3 of the falling height of the particles with the particle size of 2-4mm, namely the required height of a prilling tower is 1/5-1/3 of the prilling tower of the original high tower, and low tower prilling can be realized.
The production process of the low-tower particle fertilizer researched by the invention has the following advantages:
1. inherits all the advantages of high tower granulation series products.
2. The height of the granulation tower is reduced to be within 30 meters, and the construction cost of each production line can be reduced by about one million yuan.
3. Because the tower height is effectively reduced, the raw material is easier to convey, and the production cost is effectively reduced.
4. The reduction of the tower height makes the internal cleaning easier and the production control safer.
5. With the same formula and raw materials, the small-particle fertilizer has shorter dissolving time than a high-tower product, and is suitable for being used as a high-end full-water-soluble fertilizer.
6. The low tower process has small air input, easy dust treatment, easy control of air pollution and low environmental protection treatment cost.
7. The special structure of the low-tower granulation process atomization granulator can not cause the blockage phenomenon of the granulator, so that the production operation is easier to control than a high-tower granulator, and the production continuity is stronger.
8. The low tower granulation process has stronger formula applicability and rich product specifications.
The calcium ammonium nitrate fertilizer comprises the following components in percentage by mass: 12-30% of nitrogen and 15-30% of calcium oxide, the invention does not limit the variety of the fertilizer, and the calcium ammonium nitrate fertilizer which meets the above component ranges is in the protection range of the invention.
In the invention, preferably, the calcium ammonium nitrate fertilizer comprises the following components in percentage by mass: 15% of nitrogen and 25% of calcium oxide.
In the present invention, preferably, the calcium ammonium nitrate fertilizer described in S1 may be directly used as a calcium ammonium nitrate slurry, i.e., the process of melting into a slurry is omitted.
In the invention, preferably, the anti-hardening treatment of S5 includes coating a layer of anti-hardening agent on the surface of fertilizer granules, where the mass ratio of the anti-hardening agent to the fertilizer granules is 1-15: 1000, parts by weight; the screening is divided into three different particle materials with different particle size ranges of 0.5-1.0 mm, more than 1.0mm and less than 2.0mm and 2.0-2.5 mm.
Further preferably, the plate-preventing agent comprises the following components in parts by weight: 30-40 parts of surfactant, 15-20 parts of consistency regulator, 40-50 parts of hydrophobic agent and 15-20 parts of high molecular polymer; the consistency regulator is at least one selected from stearic acid, sodium stearate, calcium stearate, palmitic acid and sodium palmitate, the hydrophobic agent is at least one selected from diatomite, talcum powder, bentonite and silicon powder, and the high polymer is at least one selected from polyethylene glycol, polyvinyl alcohol, sodium polyacrylate and polyacrylamide.
In the invention, preferably, the particle materials with the particle size of more than 2.5mm are crushed and then used as return materials together with the particle materials with the particle size of less than 0.5mm, the return materials are preheated to 140-160 ℃ in a return material preheating device, and then the return materials enter a second reaction kettle to be continuously mixed and granulated.
In the invention, preferably, in the granulating process, the rotating speed of the granulator is set to be 300-1000 rpm, and the granulator heat tracing system and the slurry pipeline steam heat tracing system are started simultaneously to enable the granulator and the slurry pipeline to be at proper temperatures. In the invention, liquid drops thrown out of the granulating disc fall under the action of gravity, and are cooled by air in the falling process to become small-particle solids; the bottom of the granulator is provided with a receiving hopper and a fan, and air cooling can be carried out by forced ventilation through the fan or natural ventilation without installing the fan. The rotating speed of the granulator is set, so that more fertilizer granules with the grain diameter of 0.5-2.5mm can be obtained after the slurry is thrown out.
In the invention, preferably, in the granulation process, the diameters of the granulation disks are different from 100 mm to 600mm, the angles of the diversion surfaces are different from 5 degrees to 20 degrees, and the diversion angles are different from 5 degrees to 45 degrees, so that the quality and the yield of qualified products can be effectively improved by adjusting the specification parameters.
The temperature of the liquid drops is high, the air temperature is low, the liquid drops exchange heat with the air in the falling process, the air can be considered as air with the normal temperature of 25 ℃ because the air circulates, so the liquid drops can exchange heat with the air all the time as long as the temperature of the liquid drops is higher than 25 ℃, and when the temperature of the liquid drops is gradually cooled to be lower than the melting point, the liquid drops are changed into solid particles; as the solid particles fall gradually, the solid particles continue to exchange heat with the air and the temperature is gradually reduced, and as the temperature of the solid particles is reduced, the strength of the solid particles is gradually increased; when the temperature of the solid particles is reduced to 50-70 ℃, the strength of the solid particles meets the conveying requirement of a subsequent working section, at the moment, the solid particles fall onto a material collector at the bottom of the tower, are collected by the material collector and then are conveyed to the subsequent working section, and a finished product is obtained after cooling, film coating and packaging.
In the invention, preferably, the first reaction kettle and the second reaction kettle are both provided with a steam heating system, and the steam heating system is provided with a temperature sensor and a steam inlet regulating valve for controlling the heating steam amount; when the temperature sensor detects that the temperature of the slurry is higher than the set temperature, the steam inlet regulating valve reduces the opening degree and reduces the amount of steam for heating, so that the temperature is reduced; when the temperature sensor detects that the temperature of the slurry is lower than the set temperature, the steam inlet regulating valve increases the opening degree, the amount of steam for heating is increased, and the temperature is increased. The first reaction kettle and the second reaction kettle are arranged, so that the height of the granulation tower is effectively reduced on the basis of not influencing process control and product quality, the production configuration is simpler, the device is more compact, and the control is easier.
In the invention, preferably, the method further comprises a tail gas treatment process, wherein the tail gas treatment process adopts a tail gas treatment device; the tail gas treatment device comprises a dynamic wave washing tower, a dynamic wave washing tower circulating water pump, a draught fan, a washing tower circulating water pump and a chimney. The washing tower takes water as washing liquid, solid particles in the tail gas are adsorbed into the water through gas-liquid two-phase contact, the tail gas is discharged completely, the dynamic wave washing tower is characterized in that a downstream mixing element is additionally arranged in a common washing tower, so that the gas-liquid two phases are subjected to turbulent mixing again, the downstream washing effect is achieved, and the two-stage series washing effect can be realized.
Compared with the prior art, the invention has the beneficial effects that:
1. inherits all the advantages of high tower granulation series products.
2. The height of the granulation tower is reduced to about 30 meters, and the construction cost of each production line can be reduced by about one million yuan.
3. Because the tower height is effectively reduced, the raw material is easier to convey, and the production cost is effectively reduced.
4. The reduction of the tower height makes the internal cleaning easier and the production control safer.
5. With the same formula and raw materials, the small-particle fertilizer has shorter dissolving time than a high-tower product, and is suitable for being used as a high-end full-water-soluble fertilizer.
6. The low tower process has small air input, easy dust treatment, easy control of air pollution and low environmental protection treatment cost.
7. The special structure of the low-tower granulation process atomization granulator can not cause the blockage phenomenon of the granulator, so that the production operation is easier to control than a high-tower granulator, and the production continuity is stronger.
8. The low tower granulation process has stronger formula applicability and rich product specifications.
Drawings
FIG. 1 is a process flow diagram of a low-tower preparation method of a small-particle calcium fertilizer containing nitrogen and calcium oxide.
Fig. 2 is a schematic view of the structure of a pelletizing disk according to the invention.
FIG. 3 is a schematic view of centrifugal granulation by a granulation disk according to the present invention.
FIG. 4 is a schematic view of the structure of the tail gas treatment device of the present invention.
Wherein, the technical characteristics corresponding to the marks in the drawings are as follows: 1-an upper cover of a granulating disc, 2-a lower cover of the granulating disc, 3-a flow deflector, 4-a feed inlet, 5-a dynamic wave washing tower, 6-a circulating water pump of the dynamic wave washing tower, 7-an induced draft fan, 8-the washing tower, 9-a circulating water pump of the washing tower and 10-a chimney.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of the present invention is not limited to the embodiments.
The starting materials used in the following examples are all commercially available unless otherwise specified.
Example 1:
a low-tower preparation method of a small-particle calcium fertilizer containing nitrogen and calcium oxide comprises the following steps:
1. starting a steam heating system of the first reaction kettle, and slowly adding 10000kg of calcium ammonium nitrate (15% of nitrogen and 25% of calcium oxide) into the first reaction kettle. When the materials are completely melted, the slurry is continuously heated to about 150 ℃ for standby.
The calcium ammonium nitrate can also be directly used in concentrated calcium ammonium nitrate slurry, thus omitting the material melting process.
2. And opening a discharge valve of the first reaction kettle to enable all the slurry to enter a second reaction kettle, and simultaneously starting a steam heating system of the second reaction kettle to enable the temperature of the slurry in the second reaction kettle to be kept at 150-160 ℃ for later use.
3. And (3) closing a discharge valve of the first reaction kettle, and repeating the material melting process in the step (1).
4. The pelletizer was turned on and was set at the appropriate speed (950 rpm). And simultaneously starting the granulator heat tracing system and the slurry pipeline steam heat tracing system to keep the granulator and the slurry pipeline at proper temperatures.
5. The emulsifying machine is started.
6. And opening a discharge valve of the second reaction kettle, and emulsifying the prepared slurry by an emulsifying machine and then feeding the emulsified slurry into a granulator for granulation.
7. And (4) starting a material receiving belt conveyor and a screening machine at the bottom of the granulating tower, and enabling the granular materials from the granulating machine to enter the No. 1 screening machine for screening. Qualified particles within the range of 0.5-2.5mm enter a cooling system for cooling; and (3) crushing the particles larger than 2.5mm by using a crusher, returning the crushed particles and small particle materials smaller than 0.5mm to a material returning preheating device, heating the crushed particles to 150 ℃ by using the preheating device, slowly feeding the heated particles into a second reaction kettle, and mixing and granulating the particles again.
8. And (4) feeding the granular materials from the cooling system into a coating system for anti-hardening treatment.
9. The anti-hardening processed granular materials enter a No. 2 sieving machine, are classified into materials with different particle ranges of 0.5-1.0 mm/larger than 1.0 mm/smaller than 2.0 mm/2.0-2.5 mm and the like, and enter finished product bins with different specifications through a conveyer.
10. And packaging the materials in the finished product bins of various specifications by a finished product packaging system and warehousing.
11. The operations of 1 to 10 are repeated, and 15 to 0 (containing 25 percent of calcium oxide) of small-particle calcium fertilizer can be continuously produced.
The granulator that this embodiment adopted is low tower atomizing centrifugal granulator, and centrifugal granulator includes the granulation dish, the granulation dish includes from last feed inlet 4, granulation dish upper cover 1, water conservancy diversion piece 3 and the granulation dish lower cover 2 (as shown in fig. 2) that connects gradually down. The size of a slurry outlet formed by the flow deflector is 6-40 mm; after the slurry flows into the granulating disc through the feed inlet, the granulating disc rotates at a high speed, so that the slurry moves towards the edge of the granulating disc along the guide vane under the action of centrifugal force, the slurry gradually extends into a film in the moving process, and when the slurry moves to the edge of the granulating disc, the slurry is changed into fine liquid drops from the film under the action of centrifugal force and is thrown out of the granulating disc (as shown in figure 3).
The preparation process of the small-particle calcium fertilizer also comprises a tail gas treatment process, and a tail gas treatment device is adopted in the tail gas treatment process. As shown in fig. 4, the tail gas treatment device includes a dynamic wave washing tower 5, a dynamic wave washing tower circulating water pump 6, an induced draft fan 7, a washing tower 8, a washing tower circulating water pump 9 and a chimney 10.
Example 2:
a low-tower preparation method of a small-particle calcium fertilizer containing nitrogen and calcium oxide comprises the following steps:
1. starting a steam heating system of the first reaction kettle, and slowly adding 10000kg of calcium ammonium nitrate (20% of nitrogen and 20% of calcium oxide) into the first reaction kettle. When the materials are completely melted, the slurry is continuously heated to about 145 ℃ for standby.
The calcium ammonium nitrate can also be directly used in concentrated calcium ammonium nitrate slurry, thus omitting the material melting process.
2. And opening a discharge valve of the first reaction kettle to enable all the slurry to enter the second reaction kettle, and simultaneously starting a steam heating system of the second reaction kettle to enable the temperature of the slurry in the second reaction kettle to be kept at 145-150 ℃ for later use.
3. And (3) closing a discharge valve of the first reaction kettle, and repeating the material melting process in the step (1).
4. The pelletizer is turned on and brought to the appropriate speed (900 rpm). And simultaneously starting the granulator heat tracing system and the slurry pipeline steam heat tracing system to keep the granulator and the slurry pipeline at proper temperatures.
5. The emulsifying machine is started.
6. And opening a discharge valve of the second reaction kettle, and emulsifying the prepared slurry by an emulsifying machine and then feeding the emulsified slurry into a granulator for granulation.
7. And (4) starting a material receiving belt conveyor and a screening machine at the bottom of the granulating tower, and enabling the granular materials from the granulating machine to enter the No. 1 screening machine for screening. Qualified particles within the range of 0.5-2.5mm enter a cooling system for cooling; and (3) crushing the particles larger than 2.5mm by using a crusher, returning the crushed particles and small-particle materials smaller than 0.5mm to a material returning preheating device, heating the crushed particles to 145 ℃ by using the preheating device, slowly feeding the heated particles into a second reaction kettle, and mixing and granulating the particles again.
8. And (4) feeding the granular materials from the cooling system into a coating system for anti-hardening treatment.
9. The anti-hardening processed granular materials enter a No. 2 sieving machine, are classified into materials with different particle ranges of 0.5-1.0 mm/larger than 1.0 mm/smaller than 2.0 mm/2.0-2.5 mm and the like, and enter finished product bins with different specifications through a conveyer.
10. And packaging the materials in the finished product bins of various specifications by a finished product packaging system and warehousing.
11. The operations of 1 to 10 are repeated, and 20 to 0 (containing 20 percent of calcium oxide) of small-particle calcium fertilizer can be continuously produced.
Example 3:
a low-tower preparation method of a small-particle calcium fertilizer containing nitrogen and calcium oxide comprises the following steps:
1. starting a steam heating system of the first reaction kettle, and slowly adding 10000kg of calcium ammonium nitrate (25% of nitrogen and 15% of calcium oxide) into the first reaction kettle. When the materials are completely melted, the slurry is continuously heated to about 140 ℃ for standby.
The calcium ammonium nitrate can also be directly used in concentrated calcium ammonium nitrate slurry, thus omitting the material melting process.
2. And opening a discharge valve of the first reaction kettle to enable all the slurry to enter the second reaction kettle, and simultaneously starting a steam heating system of the second reaction kettle to enable the temperature of the slurry in the second reaction kettle to be kept at 140-145 ℃ for later use.
3. And (3) closing a discharge valve of the first reaction kettle, and repeating the material melting process in the step (1).
4. The pelletizer was turned on and was set at the appropriate speed (850 rpm). And simultaneously starting the granulator heat tracing system and the slurry pipeline steam heat tracing system to keep the granulator and the slurry pipeline at proper temperatures.
5. The emulsifying machine is started.
6. And opening a discharge valve of the second reaction kettle, and emulsifying the prepared slurry by an emulsifying machine and then feeding the emulsified slurry into a granulator for granulation.
7. And (4) starting a material receiving belt conveyor and a screening machine at the bottom of the granulating tower, and enabling the granular materials from the granulating machine to enter the No. 1 screening machine for screening. Qualified particles within the range of 0.5-2.5mm enter a cooling system for cooling; and (3) crushing the particles larger than 2.5mm by using a crusher, returning the crushed particles and small particle materials smaller than 0.5mm to a material returning preheating device, heating the crushed particles to 140 ℃ by using the preheating device, slowly feeding the heated particles into a second reaction kettle, and mixing and granulating the particles again.
8. And (4) feeding the granular materials from the cooling system into a coating system for anti-hardening treatment.
9. The anti-hardening processed granular materials enter a No. 2 sieving machine, are classified into materials with different particle ranges of 0.5-1.0 mm/larger than 1.0 mm/smaller than 2.0 mm/2.0-2.5 mm and the like, and enter finished product bins with different specifications through a conveyer.
10. And packaging the materials in the finished product bins of various specifications by a finished product packaging system and warehousing.
11. The operations of 1 to 10 are repeated, and 25 to 0 (containing 15 percent of calcium oxide) of small-particle calcium fertilizer can be continuously produced.
Performance testing
The small particle calcium fertilizer prepared in example 1 of the present invention was compared with a conventional calcium fertilizer on the market, both of which were calcium ammonium nitrate fertilizers. The water solubility, the water insoluble matter and the fertilizer efficiency are tested, and the results are shown in the following table:
TABLE 1
The test results show that the small-particle calcium fertilizer prepared in the embodiment 1 of the invention is fast in dispersion and dissolution in water, compared with the conventional calcium ammonium nitrate fertilizer, the dissolution time is greatly shortened, and under the same fertilizing amount condition of the same fertilizing facility, the fertilizer is fast in dissolution, the fertilizing time is shortened, the fertilizing efficiency is improved, and the yield is improved by more than 10% compared with the conventional calcium ammonium nitrate fertilizer.
Variations and modifications to the above-described embodiments may occur to those skilled in the art, which fall within the scope and spirit of the above description. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and variations of the present invention should fall within the scope of the claims of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
Claims (10)
1. A low-tower preparation method of a small-particle calcium fertilizer containing nitrogen and calcium oxide is characterized by comprising the following steps:
s1, melting a calcium ammonium nitrate fertilizer into slurry, and heating the slurry to 140-160 ℃ for later use; the viscosity of the slurry is 1000-5000 centipoises;
s2, emulsifying the slurry, and then granulating in a granulator; the granulator is a low-tower atomization centrifugal granulator, the centrifugal granulator comprises a granulating disc, and the granulating disc comprises a feed inlet, an upper granulating disc cover, a flow deflector and a lower granulating disc cover which are sequentially connected from top to bottom; the size of a slurry outlet formed by the flow deflector is 6-40 mm; after the slurry flows into the granulating disc through the feed inlet, the granulating disc rotates at a high speed, so that the slurry moves towards the edge of the granulating disc along the flow deflector under the action of centrifugal force, the slurry gradually extends into a film in the moving process, and when the slurry moves to the most edge of the granulating disc, the slurry is changed into fine liquid drops from the film under the action of centrifugal force and is thrown out of the granulating disc;
s3, screening the granular materials obtained after granulation: the granular materials with the grain diameter of 0.5-2.5mm are qualified materials; returning the granular materials with the grain diameter of more than 2.5mm and the grain diameter of less than 0.5mm together for re-mixing and granulation;
s4, cooling the qualified materials, performing anti-hardening treatment, then continuously screening, grouping, packaging and warehousing; the water content of the obtained small-particle calcium fertilizer is 0.4-1.3%.
2. The low-tower preparation method of the small-particle calcium fertilizer containing nitrogen and calcium oxide according to claim 1, wherein the small-particle calcium fertilizer is calcium ammonium nitrate fertilizer, and the calcium ammonium nitrate fertilizer comprises the following components in percentage by mass: 12-30% of nitrogen and 15-30% of calcium oxide.
3. The low tower production method of small particle calcium fertilizer containing nitrogen and calcium oxide as claimed in claim 2, wherein the calcium ammonium nitrate fertilizer comprises the following components by mass percent: 15% of nitrogen and 25% of calcium oxide.
4. The method for preparing the small particle calcium fertilizer containing nitrogen and calcium oxide in the low tower as claimed in claim 1, wherein the calcium ammonium nitrate fertilizer in S1 is directly prepared from calcium ammonium nitrate slurry, i.e. the process of melting into slurry is omitted.
5. The low-tower preparation method of the small-particle calcium fertilizer containing nitrogen and calcium oxide according to claim 1, wherein the anti-hardening treatment S4 comprises coating a layer of anti-hardening agent on the surface of fertilizer particles, and the mass ratio of the anti-hardening agent to the fertilizer particles is 1-15: 1000, parts by weight; the screening is divided into three different particle materials with different particle size ranges of 0.5-1.0 mm, more than 1.0mm and less than 2.0mm and 2.0-2.5 mm.
6. The low-tower preparation method of the small-particle calcium fertilizer containing nitrogen and calcium oxide according to claim 5, wherein the anti-caking agent comprises the following components in parts by weight: 30-40 parts of surfactant, 15-20 parts of consistency regulator, 40-50 parts of hydrophobic agent and 15-20 parts of high molecular polymer.
7. The tower-bottom preparation method of the small-particle calcium fertilizer containing nitrogen and calcium oxide as claimed in claim 1, wherein in the granulation process, the rotation speed of the granulator is set to 300-1000 rpm, and the granulator heat tracing system and the slurry pipeline steam heat tracing system are started to keep the granulator and the slurry pipeline at proper temperatures.
8. The low tower production method of nitrogen and calcium oxide containing small particle calcium fertilizer as claimed in claim 1, wherein the liquid drops thrown from the granulating pan fall under the action of gravity, and are cooled by air during the falling process to become small particle solid; the bottom of the granulator is provided with a receiving hopper and a fan, and air cooling can be carried out by forced ventilation through the fan or natural ventilation without installing the fan.
9. The low tower preparation method of the small particle calcium fertilizer containing nitrogen and calcium oxide according to claim 1, further comprising a tail gas treatment process, wherein a tail gas treatment device is adopted in the tail gas treatment process; the tail gas treatment device comprises a dynamic wave washing tower, a dynamic wave washing tower circulating water pump, a draught fan, a washing tower circulating water pump and a chimney.
10. The nitrogen and calcium oxide containing small particle calcium fertilizer prepared by the low tower preparation method of the nitrogen and calcium oxide containing small particle calcium fertilizer of any one of claims 1 to 9.
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