Granulation process, production process and system of fertilizer biological compound fertilizer

Abstract

The invention belongs to the technical field of agricultural fertilizer preparation, and particularly relates to a granulation process, a production process and a system of a fertilizer biological compound fertilizer. The granulation process comprises the following steps: firstly, uniformly mixing a powdery microbial agent and a protective agent, and then uniformly mixing with a powdery inorganic fertilizer; the survival rate of microorganisms is ensured while the content of the inorganic fertilizer is increased, then the mixed fertilizer biological compound fertilizer powder is subjected to dry granulation by adopting a double-roller extruder and is granulated by utilizing high pressure, and water or a binder does not need to be added, so that further damage of chemical reaction and osmotic pressure to the activity of the microorganisms is avoided; and the granulation process is carried out at normal temperature, and the dry granulation process is formed at one time, so that high-temperature drying is not needed subsequently, and the survival rate of microorganisms is further improved. According to the invention, the double-roller extrusion granulator is adopted for granulation, the whole granulation process is continuously carried out, the preparation efficiency is high, the granules do not need to be dried subsequently, and the production cost is reduced.

Description

A granulation process, production process and system for chemical fertilizer and biological compound fertilizer Technical Field

[0001] The present invention belongs to the technical field of agricultural fertilizer preparation, and in particular relates to a granulation process, a production process and a system for a chemical fertilizer and biological compound fertilizer. Background Art

[0002] Compound fertilizers, which contain two or more nutrients, offer advantages such as high nutrient content, ease of transportation, and mechanical application. However, due to excessive and irrational application, nitrogen and phosphorus fertilizer utilization rates are approximately 20 percentage points lower than in developed countries. Research has shown that the synergistic effect of microbial agents with chemical fertilizers can improve fertilizer utilization efficiency. Due to their price, their use rate is low, typically 10-20 kg / mu. Application alone in fields results in uneven fertilization, ineffectiveness, and increased fertilization costs, leading to low farmer acceptance. The agricultural industry standard NY / T798-2015 (compound microbial fertilizers) includes chemical fertilizers, microbial agents, and organic fertilizers. However, the standard specifies a maximum total nitrogen, phosphorus, and potassium nutrient content of 8-25%, and an agent content of at least 20 million cfu / g. The low microbial content in these fertilizers prevents them from fully functioning. Furthermore, to ensure microbial survival, most commercially available compound microbial fertilizers are in powder form, making them difficult to mechanically apply in fields. The price of granular fertilizers in this category is relatively high, 1,500-2,500 yuan per ton. The cost of using it on field crops is too high, so farmers generally do not use it.

[0003] High-nutrient compound fertilizers can meet the nutritional needs of crops, require minimal application, and are easy to use. However, their high nutrient concentration creates a high-salinity environment within the fertilizer, and it's difficult to incorporate sufficient organic matter and other microbial protective ingredients into the formula, making it difficult for microorganisms to survive long-term in these fertilizers. Years of application have shown that problems with maintaining bacterial strain viability and unstable field application results persist.

[0004] In the existing preparation process of compound microbial fertilizers, there are two ways to add microorganisms. One is to mix the bacterial strain with traditional fertilizers and granulate them, and the other is to spray the bacterial strain after granulation. In the traditional wet granulation process, high temperature and high salt content will cause a large number of microorganisms to die. Inorganic fertilizers, especially high nitrogen, have a strong killing effect on microorganisms. The spraying method has a higher microbial survival rate, but there are still problems such as the microbial fertilizer cannot be stored for a long time, the shelf life is short, the number of viable bacteria drops sharply in a short period of time, and the friction of the particles during storage and transportation causes the bacterial powder to fall off.

[0005] Therefore, preparing fertilizers with high nutrient content and containing highly active functional microbial agents, and being able to apply both simultaneously to the soil, is one of the effective measures to address low fertilizer utilization and improve crop nutrient absorption. However, uniformly mixing high-salinity fertilizers with live beneficial microorganisms to form biocomposite fertilizers while maintaining high activity of the beneficial microorganisms remains a global challenge. To ensure the effectiveness of biocomposite fertilizers, addressing the microbial activity issue is crucial.

[0006] Summary of the Invention

[0007] The object of the present invention is to solve the above-mentioned problems. In view of the deficiencies in the prior art, the present invention adopts a low-temperature, high-pressure dry-method live-keeping physical granulation process, mixes powdered microbial agents and protective agents, and then directly adds them to a powdered inorganic compound fertilizer raw material without adding a binder or water. Strong pressure is used to overcome the intermolecular binding force of the powder, and the mixed material is dry-pressed into granules at room temperature to make the powder into a dry-pressed type. The granulation process does not destroy the activity of the microorganisms and the protective agent. After abrasive polishing, screening, and packaging, a high-nutrient and high-activity chemical fertilizer biological compound fertilizer is obtained. The obtained chemical fertilizer biological compound fertilizer particles are round, with a particle size of 2.8-4.75 mm and a hardness of 30-40N.

[0008] The technical problem to be solved by the present invention is achieved by the following technical solution: a granulation process for chemical fertilizer and biological compound fertilizer, wherein powdered chemical fertilizer and biological compound fertilizer raw materials with good proportion and uniform mixing are dry granulated by a double-roll granulator, and no binder or water is added during the dry granulation process;

[0009] The cross section of the forming hole on the surface of the extrusion roller of the roller granulator is a regular hexagon;

[0010] The raw materials for preparing the chemical fertilizer and biological compound fertilizer include inorganic fertilizer, microbial agent and protective agent, and the process is carried out under normal temperature conditions;

[0011] The protective agent protects the microbial agent and is used to balance the osmotic pressure of the microorganisms. The low-temperature and high-pressure dry granulation process adopted by the present invention overcomes the problems of high moisture content in pelleting and low survival rate of microorganisms in high-temperature drying in traditional granulation processes. Due to the use of new equipment for forming compound fertilizers with regular hexagonal roller extrusion, various materials of ordinary compound fertilizers can be formed at room temperature by adding microbial agents, microbial protective agents, etc., without the need for high-temperature drying and granulation. Compared with ordinary roller granulators, it has wide material adaptability, low granulation temperature, 20% higher particle hardness, 7-8% higher product qualification rate, 9-10% lower dust pollution, 8-10% higher production efficiency of the entire equipment, and 50% lower production cost than traditional granulation processes.

[0012] The present invention also discloses a production process of a chemical fertilizer and biological compound fertilizer, comprising the following steps:

[0013] S1. Ingredients: Weigh the powdered inorganic fertilizer raw materials, microbial agents and protective agents separately according to the fertilizer formula, first mix the microbial agents and protective agents evenly, and then stir them with the inorganic fertilizer raw materials using a stirring device to mix them evenly;

[0014] The protective agent protects the microbial agent and is used to balance the osmotic pressure of the microorganisms. Osmotic pressure refers to the attraction of solute particles in a solution to water. The amount of water content in the cell depends on the osmotic pressure. When sodium chloride, a solute with cell membrane permeability, passes through the cell membrane, the sodium chloride also brings water in or out of the cell membrane. At this time, the contents of the cell will change, thereby causing cell damage or necrosis. That is, when the salt content of the environment is high, the free water in the cell will flow from the high water potential inside the cell to the low water potential outside the cell, causing cell dehydration and apoptosis; when the salt content of the environment is low, water is transferred from the environment to the cell, causing cell edema and necrosis. The present invention uses a protective agent to protect the microbial agent and is used to balance the osmotic pressure of the microorganism.

[0015] S2, feeding the uniformly mixed compound fertilizer raw materials into a double-roll granulator for dry granulation, wherein the cross-section of the shaped holes on the surface of the extrusion roller of the double-roll granulator is a regular hexagon;

[0016] The dry granulation process does not require the addition of binders or water and is carried out at room temperature.

[0017] The present invention also provides a technical solution in which, in step S1, the powdered microbial agent is directly dried and prepared using a bacterial solution prepared by a fermentation process. In the production of bio-compound fertilizers, the powdered microbial agent is directly dried and prepared using a bacterial solution prepared by a fermentation process, thereby integrating processes, simplifying the process, and improving production efficiency. Compared to purchasing microbial agents or other preparation processes, the microbial agent can meet mass production requirements and achieve greater cost savings.

[0018] The technical solution of the present invention also includes the following: In step S1, the inorganic fertilizer raw material is weighed using a quantitative metering scale, and the microbial agent and protective agent are weighed using a loss-in-weight scale. A loss-in-weight scale is an automatic weighing device that achieves high-precision continuous quantitative feeding through static weighing. It can reliably, accurately, and stably feed dry bulk materials such as powders, granules, and flakes, reducing material waste and improving the consistency of the mixture. In the present invention, the use of a loss-in-weight scale allows for precise feeding of trace amounts of microbial agents and protective agents, ensuring their uniform distribution within the compound fertilizer.

[0019] The present invention also includes a technical solution: In step S1, the protective agent includes brown algae oligosaccharides and ectoine. Ectoine effectively protects the proteins in the spore coat by forming "ectoine hydrates," preventing cations from entering the spores, thereby maintaining the stability and activity of the spores in high-concentration fertilizer environments. Brown algae oligosaccharides, through their polyhydroxy groups, maintain the natural structure of the microbial cell macromolecules in the chemical biocompound fertilizer in their original hydrated state. They also form a vitrified matrix around the cells, acting like a physical barrier to resist damage to the cells from high salt concentrations, minimizing the loss of cell vitality and thus providing a protective effect.

[0020] The technical solution of the present invention also includes: in step S1, the protective agent further includes at least one of burdock oligosaccharide, chitosan oligosaccharide, amino acid, vegetable oil, fumaric acid and citric acid. Among them, burdock oligosaccharide, chitosan oligosaccharide and amino acid simultaneously maintain the natural structure of the microbial cell biomacromolecules in the chemical fertilizer biocompound fertilizer in the original hydrated state through the polyhydroxy groups contained in each of them, and at the same time form a vitrified matrix around the cells, similar to a physical barrier, to resist the damage of high concentration of salt to the cells, so that the cells suffer less loss of vitality, thereby playing a protective role.

[0021] The function of vegetable oil is to increase hydrophobicity and prevent microorganisms from coming into contact with fertilizers and water.

[0022] The function of fumaric acid and citric acid is to enhance the rhizosphere chemotaxis and root surface film formation of beneficial microorganisms in chemical fertilizer and biological compound fertilizer, improve the colonization of microorganisms in the soil, and increase the rhizosphere colonization of microorganisms by 2.0 to 6.0 times.

[0023] The technical solution of the present invention also includes the following steps:

[0024] Step S3, abrasive polishing: performing abrasive polishing on the particles generated in step S2;

[0025] Step S4, screening: the polished particles are screened according to the particle size requirements, and the particles that do not meet the particle size requirements enter the return system for re-granulation;

[0026] Step S5: Packaging: Packing the qualified fertilizer granules.

[0027] The present invention also discloses a production system of chemical fertilizer and biological compound fertilizer, comprising a first weighing device, a second weighing device, a first stirring device, a second stirring device and a roller granulator;

[0028] The first weighing device is used to quantitatively weigh the powdered inorganic fertilizer;

[0029] The second weighing device is used to weigh the powdered microbial agent and protective agent by weight loss;

[0030] The first stirring device is used to uniformly mix the microbial agent and protective agent weighed by the second weighing device;

[0031] The second stirring device is used to mix the mixture of the microbial agent and the protective agent with the inorganic fertilizer to obtain a powdered chemical fertilizer bio-compound fertilizer;

[0032] The double-roller granulator is used to dry granulate powdered chemical fertilizer and biological compound fertilizer at room temperature;

[0033] The cross section of the forming hole on the surface of the extrusion roller of the double-roller granulator is a regular hexagon.

[0034] The technical solution of the present invention also includes: a bacterial liquid fermentation device and a drying device, and the bacterial liquid fermentation device is connected to the second weighing device through the drying device.

[0035] The present invention also discloses an application of a double-roll granulator in the dry granulation of chemical fertilizer and biological compound fertilizer. The cross-section of the forming hole on the surface of the extrusion roller of the double-roll granulator is a regular hexagon. The raw materials for preparing the chemical fertilizer and biological compound fertilizer are powdered. No binder or water needs to be added during the dry granulation process, and the process is carried out at room temperature. Other extrusion granulation equipment has a low granulation rate and can only select powdered raw materials that are easy to granulate. At the same time, in order to improve the granulation rate and particle strength, the granulation process requires additional water, so a subsequent drying and cooling process is required, which not only increases energy consumption but also has a serious impact on the survival rate and shelf life of microorganisms. Therefore, it is not suitable for the production of high-nutrient, high-activity chemical fertilizer and biological compound fertilizer. The present invention found through testing that the double-roll granulator with a regular hexagonal cross-section of the forming hole on the surface of the extrusion roller effectively overcomes the above-mentioned defects, is suitable for all kinds of powdered raw materials, can achieve granulation without adding binders or water, and ensures that the strength of the granulation meets the use requirements.

[0036] The advantages of the present invention are as follows: since conventional double-roller granulators directly adopt dry granulation for granulating chemical fertilizer and biological compound fertilizer, the hardness of the particles cannot meet the requirements, water needs to be added during the granulation process, and drying is required in the later stage to ensure the hardness of the particles. The subsequent drying process of granulation is a high-temperature process, which will reduce the survival rate of microorganisms. However, the production process of the chemical fertilizer and biological compound fertilizer of the present invention does not have a drying process, thereby avoiding the influence of the high-temperature drying process on the activity of microorganisms, and the hardness of the granulated product reaches the standard of 30-40N.

[0037] In conventional processes, fertilizers dissolve after water is added, and microorganisms come into direct contact with the inorganic salt solution, significantly reducing their survival time. This process uses dry extrusion granulation without the addition of water, avoiding the generation of high osmotic pressure. Protective agents are also added to protect microbial activity, resulting in a biocompound fertilizer produced using this process with a viable count exceeding 200 million cfu / g.

[0038] Compared to traditional disc granulation, the granulation process does not require the addition of water or high temperature, and there is no subsequent drying process. Compared with traditional roller granulation, this invention has a high granulation rate and low production costs. It has an automatic adjustment system for the extrusion pressure, which can be adjusted according to the characteristics of different raw materials.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) The present invention utilizes an extrusion granulator with a regular hexagonal shaped hole on the surface of an extrusion roller to granulate chemical fertilizer and biological compound fertilizer, thereby realizing granulation under normal temperature and high pressure conditions. In addition, the granulation process can prepare granules with a hardness that meets the standard without adding water or a binder, thereby avoiding the high temperature and osmotic pressure in the granulation process that reduce the survival rate of microorganisms, and at the same time avoiding the influence of high temperature on the survival rate of microorganisms in the subsequent drying process.

[0041] (2) The present invention first mixes powdered microbial agents and protective agents evenly with each other and then mixes them evenly with powdered inorganic fertilizers. The protective agent is used to protect the microorganisms to balance the osmotic pressure of the microorganisms, ensuring that the survival rate of the microorganisms is guaranteed while the content of inorganic fertilizers is increased. The mixed chemical fertilizer and biological compound fertilizer powder is then dry-granulated using a double-roll extruder and granulated using high pressure. Since no water or binder is required, further damage to the activity of the microorganisms by chemical reactions and osmotic pressure is avoided. Moreover, since the granulation process is carried out at room temperature, the reduction in microbial activity caused by high temperature during the granulation process is avoided. In addition, since the dry granulation process is formed in one step, no high-temperature drying is required subsequently, thereby further improving the survival rate of the microorganisms.

[0042] (3) The preparation process of the present invention uses a double-roll extrusion granulator for granulation, and the entire granulation process is carried out continuously, with high preparation efficiency. There is no need for subsequent drying of the granules, which reduces the overall process cost and improves production efficiency. In addition, since the preparation equipment for the powdered microbial agent in the preparation process of the present invention is directly connected to the granulation process, the packaging and secondary transportation of the microbial agent raw materials are avoided, and the entire preparation process is seamlessly connected. Compared with other granular compound fertilizer preparation processes, the preparation process is complete and smooth, reducing the preparation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] FIG1 is a flow chart of the production process of the chemical fertilizer bio-compound fertilizer of the present invention;

[0044] FIG2 is a schematic structural diagram of the roller granulator of the present invention;

[0045] In the figure, 1 is a first weighing device, 2 is a second weighing device, 3 is a first stirring device, 4 is a second stirring device, 5 is a pair of roller granulators, and 51 is a surface forming hole of an extrusion roller;

[0046] 6 first feeding device, 7 abrasive polishing device, 8 screening device, 9 packaging equipment, 10 dust removal device, 11 second feeding device, 12 bacterial liquid fermentation equipment, 13 drying equipment. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0048] A double-roller granulator is used in the dry granulation of chemical fertilizer and bio-compound fertilizer. The cross-section of the shaped holes on the surface of the extrusion rollers of the double-roller granulator is a regular hexagon. The raw materials for preparing the chemical fertilizer and bio-compound fertilizer are in powder form. The dry granulation process does not require the addition of a binder or water, and is carried out at room temperature. Double-roller granulators are currently available. This applicant has found that only a double-roller granulator with a regular hexagonal cross-section of the shaped holes on the surface of the extrusion rollers meets the requirements of the present invention for dry granulation of chemical fertilizer and bio-compound fertilizer. That is, it can produce fertilizer granules with the required hardness at room temperature without the addition of a binder or water.

[0049] A granulation process for chemical fertilizer and biological compound fertilizer comprises the following steps: using a double-roller granulator to dry granulate chemical fertilizer and biological compound fertilizer preparation raw materials that are well-proportioned and evenly mixed in powder form; during the dry granulation process, no binder or water is added and the process is carried out at room temperature.

[0050] The cross section of the forming hole on the surface of the extrusion roller of the double-roller granulator is a regular hexagon.

[0051] The raw materials for preparing the chemical fertilizer and biological compound fertilizer include inorganic fertilizer, microbial agent and protective agent.

[0052] A production process of a chemical fertilizer and biological compound fertilizer comprises the following steps:

[0053] S1. Ingredients: According to the fertilizer formula, the powdered nitrogen, phosphorus, potassium fertilizer, inorganic fertilizer raw materials, microbial agents and protective agents are weighed separately. The microbial agents and protective agents are first evenly mixed, and then sent to the agitator mixer with the inorganic fertilizer raw materials through the elevator for stirring. After mixing evenly, the mixture is sent to the feeding device.

[0054] The protective agent protects the microbial agent and is used to balance the osmotic pressure of the microorganisms.

[0055] S2. The uniformly mixed compound fertilizer raw materials are fed into a double-roller granulator through a feeding device for dry granulation. The cross-section of the formed holes on the surface of the extrusion roller of the double-roller granulator is a regular hexagon.

[0056] No binder or water needs to be added during the dry granulation process, and the process is carried out at room temperature. The extrusion pressure of the dry granulation process is 0.7 Ma, and the extrusion temperature is 23±3°C.

[0057] In step S1, the powdered microbial agent is directly prepared by drying the bacterial liquid prepared by the fermentation process.

[0058] In step S1, the inorganic fertilizer raw material is weighed using a quantitative metering scale, and the microbial agent and protective agent are weighed using a weight loss scale.

[0059] Specifically, when weighing microbial agents and protective agents, the control system collects the weight reduction of the material in the measuring hopper per unit time in real time, calculates the actual flow rate of the loss-in-weight scale, compares the actual feeding speed with the preset feeding speed, and feeds the comparison result back to the feeding mechanism of the loss-in-weight scale to automatically correct the feeding speed of the feeding mechanism, forming a closed-loop control. In order to ensure uniform mixing of trace raw materials, the gravimetric scale uses the measuring hopper and the entire feeding mechanism as a scale body for weighing. As the material flows out of the loss-in-weight scale, the control system performs a high-speed, high-frequency collection of the weight signal of the scale body to obtain the weight reduction of the material in the measuring hopper per unit time. Then, through unique filtering and optimization processing, the actual flow rate of the loss-in-weight scale is obtained. At the same time, the control system compares this feeding speed with the preset given speed, and feeds the comparison result back to the feeding mechanism of the loss-in-weight scale to automatically correct the feeding speed of the feeding mechanism, forming a closed-loop control, so that the actual flow rate is infinitely close to the given flow rate, thereby achieving precise control requirements. The specific control method is existing technology and will not be described in detail here.

[0060] This invention utilizes a fertilizer production material weighing and flow signal acquisition, conversion, and processing system. Through computer-based intelligent control of instantaneous material flow, it accurately allocates both large and small quantities of raw materials. A toothed mixer is then used for uniform mixing. This achieves uniform addition and high-quality mixing of trace materials, such as microbial agents and protective agents, at levels below 2kg / ton, resulting in a uniform product. Different flow addition rates are calculated based on the characteristics of the raw materials, as conventional weighing scales struggle to evenly mix trace materials.

[0061] In step S1, the protective agent includes brown algal oligosaccharide and ectoine.

[0062] In step S1, the protective agent further comprises at least one of burdock oligosaccharide, chitosan oligosaccharide, amino acid, vegetable oil, fumaric acid and citric acid.

[0063] The production process of the chemical fertilizer bio-compound fertilizer also includes the following steps:

[0064] Step S3, abrasive polishing: performing abrasive polishing on the particles produced in step S2; specifically, the fertilizer particles are transported to the abrasive polishing device via a conveyor belt and an elevator for polishing.

[0065] Step S4, screening: the polished particles are screened according to the particle size requirements, and the particles that do not meet the particle size requirements enter the return system for re-granulation; specifically, the polished particles enter the vibrating screen to screen out fertilizer particles with a particle size of 2.8-4.75 mm, and the particles that do not meet the standards enter the return system and return to the roller extruder for re-granulation.

[0066] Step S5, packaging: Packaging the qualified fertilizer particles. After screening, the obtained product is further packaged: using an automatic packaging machine to package, thus obtaining a high-nutrient and high-activity chemical fertilizer bio-compound fertilizer product.

[0067] The present invention provides a high-nutrient, high-activity bio-compound fertilizer production process for producing fertilizers with a total chemical nutrient content of 40-50% and a viable microbial count of 200 million cfu / g or greater. The chemical nutrient content exceeding 40% in the present invention refers to a total mass percentage of N, P2O5, and K2O in the fertilizer exceeding 40%.

[0068] As shown in FIG1 , a production system of chemical fertilizer and bio-compound fertilizer includes a first weighing device 1 , a second weighing device 2 , a first stirring device 3 , a second stirring device 4 and a double-roller granulator 5 .

[0069] The first weighing device 1 is used to quantitatively weigh powdered inorganic fertilizer. The first weighing device 1 is a quantitative measuring scale.

[0070] The second weighing device 2 is used to weigh the powdered microbial inoculant and protective agent by weight loss. The second weighing device 2 is a weight loss scale.

[0071] The first stirring device 3 is used to uniformly mix the microbial agent and protective agent weighed by the second weighing device 2 .

[0072] The second stirring device 4 is used to mix the mixture of microbial agent and protective agent with inorganic fertilizer to obtain powdered chemical fertilizer and biological compound fertilizer. The second stirring device 4 is a toothed mixer.

[0073] The double-roller granulator 5 is used to perform dry granulation on powdered chemical fertilizer and biological compound fertilizer under normal temperature conditions.

[0074] As shown in FIG2 , the cross section of the formed hole 51 on the surface of the extrusion roller of the double-roller granulator 5 is a regular hexagon.

[0075] As shown in Figure 1, the production system of chemical fertilizer and biological compound fertilizer also includes a first feeding device 6. The discharge ports of the first weighing device 1 and the first stirring device 3 are connected to the first feeding device 6, and the outlet of the first feeding device 6 is connected to the second stirring device 4. The first feeding device 6 includes a conveyor belt and an elevator. The conveyor belt is located below the discharge ports of the first weighing device 1 and the first stirring device 3, and the conveyor belt is located above the elevator inlet.

[0076] As shown in Figure 1, the chemical fertilizer and bio-compound fertilizer production system also includes an abrasive polishing device 7, a screening device 8, and a packaging device 9. The inlet of the abrasive polishing device 7 is connected to the outlet of the roller granulator 5, the inlet of the screening device 8 is connected to the outlet of the abrasive polishing device 7, and the outlet of the screening device 8 is connected to the packaging device 9. The screening device 8 is a vibrating screening device. The packaging device 9 is used to package the prepared products.

[0077] The return port of the screening device 8 is connected to the second stirring device 4. The particles that fail the screening are returned to the second stirring device 4 through the return port of the screening device 8 to be dispersed and mixed before granulation.

[0078] As shown in FIG1 , the chemical fertilizer and bio-compound fertilizer production system further includes a dust removal device 10. The dust outlets of the abrasive polishing device 7 and the screening device 8 are respectively connected to the inlet of the dust removal device 10, and the outlet of the dust removal device 10 is connected to the second stirring device 4. The dust removal device 10 includes a bag dust collector for recycling fertilizer dust generated by the abrasive polishing device 7 and the screening device 8, thereby reducing dust pollution and achieving material recycling.

[0079] As shown in FIG1 , the production system of chemical fertilizer and bio-compound fertilizer further includes a second feeding device 11. The outlet of the second stirring device 4 is connected to the inlet of the double-roller granulator 5 via the second feeding device 11. The residual material outlet of the second feeding device 11 is connected to the inlet of the second stirring device 4. The second feeding device 11 is connected to the inlet of multiple second stirring devices 4 to improve granulation efficiency. The residual material in the second feeding device 11 is returned to the second stirring device 4 through the residual material outlet for dispersion and mixing before granulation for recycling.

[0080] As shown in Figure 1, the chemical fertilizer and bio-compound fertilizer production system also includes a bacterial liquid fermentation device 12 and a drying device 13. The bacterial liquid fermentation device 12 is connected to the second weighing device 2 via the drying device 13. Directly connecting the bacterial liquid fermentation device 12 to the second weighing device 2 via the drying device 13 simplifies the process and improves production efficiency. Compared with purchasing microbial inoculants or other preparation processes, the microbial inoculant production method of this embodiment is more cost-effective.

[0081] Example 1

[0082] The production process of the chemical fertilizer and biological compound fertilizer of the above embodiment of the present invention was used to prepare the chemical fertilizer and biological compound fertilizer. The protective agent used in this application was used as the protective agent. The viable bacterial count of the prepared compound fertilizer was tested on different days. The specific data is shown in Table 1.

[0083] Example 2

[0084] The difference from Example 1 is that the protective agent is a protective agent composed of polyvinyl alcohol and a deep eutectic solvent disclosed in patent document CN105219645B. The viable bacterial count of the prepared compound fertilizer was tested on different days, and the specific data is shown in Table 1.

[0085] Comparative Example 1

[0086] The difference from Example 1 is that no protective agent is added, and the viable bacterial count of the prepared compound fertilizer is tested on different days. The specific data are shown in Table 1.

[0087] Table 1 Viable bacteria count (100 million cfu / g)

[0088] By comparing the data in Table 1, it can be concluded that when no protective agent is added, the number of viable bacteria in Comparative Example 1 will drop significantly, and the requirements for long-term transportation and storage cannot be met; and although the existing protective agent has a certain protective effect, it can be concluded from the data of Example 2 that the protective effect of the existing protective agent on microorganisms is limited. After long-term storage, the number of viable microorganisms in the fertilizer and biological compound fertilizer will be less than 200 million cfu / g. However, from the test data of Example 1, it can be concluded that the fertilizer and biological compound fertilizer prepared using the protective agent of the present invention has a viable microorganism count of more than 200 million cfu / g even after long-term storage, which better meets the actual production and use needs.

[0089] Comparative Example 2

[0090] The difference from Example 1 is that this comparative example uses an existing common double-roll granulator for granulation and uses the method of the present invention to prepare chemical fertilizer and bio-compound fertilizer. The cross section of the formed hole on the surface of the extrusion roller of the common double-roll granulator is elliptical.

[0091] Table 2 shows the test data of a common double-roll granulator and the regular hexagonal double-roll extrusion equipment used in the present invention.

[0092] Table 2

[0093] From the comparison of the above data, it can be concluded that the granulation rate of the ordinary double-roller granulator is low, resulting in high preparation cost and inability to meet mass production; and the hardness of the prepared granules is lower than 30N, which cannot meet the requirements of export products, thus limiting the dry preparation of chemical fertilizer and bio-compound fertilizer by technicians in this field.

[0094] This invention utilizes a new, hexagonal, double-roller extrusion-type compound fertilizer forming machine, enabling the simultaneous, room-temperature forming of various conventional compound fertilizer materials with microbial agents and protective agents, eliminating the need for high-temperature drying and granulation. Compared to conventional double-roller granulators, this machine offers a wider range of material adaptability, lower granulation temperatures, a 7-8% increase in granulation rate, and over 20% improvement in granule hardness, reaching 30N or higher. Product moisture can be controlled below 0.5%. This increased granulation rate reduces production energy consumption, contributing to cost savings and meeting mass production requirements.

Claims

1. A granulation process for chemical fertilizer and biological compound fertilizer, characterized in that: The powdered fertilizer and bio-compound fertilizer raw materials that are well-proportioned and mixed evenly are dry-granulated by a roller granulator. No binder or water is required during the dry granulation process, and the process is carried out at room temperature. The cross section of the forming hole on the surface of the extrusion roller of the double-roll granulator is a regular hexagon; The raw materials for preparing the chemical fertilizer and biological compound fertilizer include inorganic fertilizer, microbial agent and protective agent; The protective agent protects the microbial agent and is used to balance the osmotic pressure of the microorganisms.

2. A production process of chemical fertilizer biocompound fertilizer, characterized in that: The following steps are involved: S1. Batching: Weigh the powdered inorganic fertilizer raw materials, microbial agents and protective agents respectively according to the fertilizer formula, first mix the microbial agents and protective agents evenly, and then stir them with the inorganic fertilizer raw materials using a stirring device to mix them evenly; The protective agent protects the microbial agent and is used to balance the osmotic pressure of the microorganisms; S2, feeding the uniformly mixed compound fertilizer raw materials into a double-roll granulator for dry granulation, wherein the cross-section of the forming hole on the surface of the extrusion roller of the double-roll granulator is a regular hexagon; The dry granulation process does not require the addition of binders or water and is carried out at room temperature.

3. The production process of the chemical fertilizer biocomposite fertilizer according to claim 2, characterized in that: In step S1, the powdered microbial inoculant is directly prepared by drying the bacterial liquid prepared by the fermentation process.

4. The production process of the chemical fertilizer biocomposite fertilizer according to claim 2, characterized in that: In step S1, the inorganic fertilizer raw material is weighed by a quantitative measuring scale, and the microbial agent and protective agent are weighed by a weight loss scale.

5. The production process of the chemical fertilizer biocomposite fertilizer according to claim 2, characterized in that: In step S1, the protective agent includes brown algae oligosaccharide and ectoine.

6. The production process of the chemical fertilizer and biological compound fertilizer according to claim 5 is characterized in that: In step S1, the protective agent further comprises at least one of burdock oligosaccharide, chitosan oligosaccharide, amino acid, vegetable oil, fumaric acid and citric acid.

7. The production process of chemical fertilizer and biological compound fertilizer according to claim 2, characterized in that: The following steps are also included: Step S3, abrasive polishing: performing abrasive polishing on the particles generated in step S2; Step S4, screening: the polished particles are screened according to the particle size requirements, and the particles that do not meet the particle size requirements enter the return system for re-granulation; Step S5, packaging: packaging the qualified fertilizer particles.

8. A production system of chemical fertilizer and biological compound fertilizer, characterized in that: It comprises a first weighing device (1), a second weighing device (2), a first stirring device (3), a second stirring device (4) and a double-roll granulator (5); The first weighing device (1) is used to quantitatively weigh powdered inorganic fertilizer; The second weighing device (2) is used to weigh the powdered microbial agent and protective agent by weight loss; The first stirring device (3) is used to evenly mix the microbial agent and the protective agent weighed by the second weighing device (2); The second stirring device (4) is used to mix the mixture of the microbial agent and the protective agent with the inorganic fertilizer to obtain a powdered chemical fertilizer biological compound fertilizer; The double-roll granulator (5) is used to perform dry granulation on powdered chemical fertilizer and biological compound fertilizer under normal temperature conditions; The cross section of the formed hole (51) on the surface of the extrusion roller of the double-roll granulator (5) is a regular hexagon.

9. The production system of chemical fertilizer and biological compound fertilizer according to claim 8, characterized in that: It also includes a bacterial liquid fermentation device (12) and a drying device (13), wherein the bacterial liquid fermentation device (12) is connected to the second weighing device (2) via the drying device (13).

10. Application of a double-roll granulator in dry granulation of chemical fertilizer and biological compound fertilizer, characterized in that: The cross section of the forming hole on the surface of the extrusion roller of the double-roll granulator is a regular hexagon. The raw material for preparing the chemical fertilizer and biological compound fertilizer is in powder form. No binder or water needs to be added during the dry granulation process, and the process is carried out under normal temperature conditions.

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