A system and process for preparing organic compound fertilizer using waste

Abstract

The present invention belongs to the technical field of organic waste recycling, and specifically relates to a system and process for preparing organic compound fertilizer from waste. The system for preparing organic compound fertilizer from waste comprises a dryer, a crusher, and a reactor, a screw granulator, a powder coating machine and a screening device which are sequentially connected through pipelines. The process for preparing organic compound fertilizer from waste can use sodium carbonate mother liquor, thiourea dioxide mother liquor and plant ash as raw materials, and prepare organic compound fertilizer through granulation, powder coating, screening, drying and other processes, and has a high raw material utilization rate. The system of the present invention selects large particles and small particles through a screening device, and the large particles are sent to the crusher for re-crushing, thereby improving the utilization rate of granulation. The process utilizes sodium carbonate in the flocculation precipitate of sodium percarbonate mother liquor to react with thiourea dioxide to decompose thiourea dioxide into urea and sulfate, without the need to use new sodium carbonate, thereby reducing costs.

Description

Technical Field

[0001] The invention belongs to the technical field of organic waste recycling, and specifically relates to a system and process for preparing organic compound fertilizer by utilizing waste. Background Art

[0002] Sodium percarbonate is widely used in washing, textile, chemical synthesis and other fields. At present, the wet method is generally used for the production of sodium percarbonate at home and abroad. The disadvantage of this method is that it will produce salt-containing and alkali-containing mother liquor, and it is difficult to handle. Since the content of alkali and sodium chloride in the sodium percarbonate mother liquor is high, it needs to be neutralized and diluted before use, and the post-treatment cost is high. In the production process of sodium percarbonate mother liquor, since sodium polyacrylate is a viscous liquid, it is easy to produce flocculent precipitates after mixing with particulate matter (sodium carbonate, sludge, etc.) in the sodium percarbonate mother liquor. Therefore, how to efficiently utilize the sodium percarbonate mother liquor and the sodium polyacrylate, sodium carbonate, sludge, etc. therein has always been a technical problem for production enterprises.

[0003] The mother liquor wastewater generated in the production of thiourea dioxide is generally treated by biochemical method, which is costly and not suitable for popularization and application. Therefore, how to treat the mother liquor of thiourea dioxide at low cost and low energy consumption is also an urgent problem to be solved.

[0004] During the gasification process of biomass raw materials, wood ash is produced, which can be used as a raw material for preparing fertilizers. However, since wood ash is light and flies up a lot, water must be used to reduce dust in the process of preparing fertilizers. Adding a small amount of water will cause agglomeration, and adding too much water will form a paste that is difficult to transport. In the prior art, the use of wood ash to prepare fertilizers requires the addition of a large amount of adhesive, and the content of wood ash is relatively small, resulting in low utilization rate.

[0005] In summary, in order to improve the utilization rate of wood ash in preparing fertilizers, sodium percarbonate mother liquor, thiourea dioxide mother liquor and wood ash can be mixed to prepare slurry, granulated, and dried to obtain organic fertilizer, in order to achieve comprehensive utilization of wood ash. Summary of the invention

[0006] In view of the problems existing in the prior art, the purpose of the present invention is to provide a system and process for preparing organic compound fertilizer using waste, which can use sodium carbonate mother liquor, thiourea dioxide mother liquor and wood ash as raw materials, and prepare organic compound fertilizer through granulation, powder coating, screening, drying and other processes, and has a high raw material utilization rate.

[0007] Based on the above purpose, the present invention adopts the following technical solutions:

[0008] A system for preparing organic compound fertilizer using waste, comprising a dryer, a crusher, and a reactor, a screw granulator, a powder coating machine and a screening device which are sequentially connected through a pipeline;

[0009] An upper screen and a lower screen are arranged in the screening device, and the upper screen and the lower screen separate the inner cavity of the screening device into an upper cavity, a middle cavity and a lower cavity from top to bottom;

[0010] The inlet end of the screening device is connected to the upper cavity;

[0011] The upper cavity of the screening device is connected to the inlet end of the crusher through a pipeline, and the outlet end of the crusher is connected to the reactor through a pipeline;

[0012] The middle cavity of the screening device is connected to the dryer through a pipeline;

[0013] The lower cavity of the screening device is connected to the reactor through a pipeline;

[0014] The mesh aperture of the upper mesh is larger than the mesh aperture of the lower mesh.

[0015] Specifically, the screw granulator can extrude and granulate the mixed materials.

[0016] Specifically, a first transfer pump is provided on the pipeline connecting the screw granulator and the powder coating machine, and the particles extruded by the screw granulator are pressurized and fed into the powder coating machine through the first transfer pump.

[0017] Specifically, the powder coating machine includes a rotating drum. When in use, the materials are mixed, and then granular materials or powder materials such as wood ash and straw are added. The rotation of the rotating drum is used to coat the surface of the materials with wood ash or straw.

[0018] Specifically, a second conveying pump is provided on the pipeline connecting the breading machine and the screening device; the particles processed by the breading machine are pressurized and sent to the screening device through the second conveying pump.

[0019] Preferably, the particle size after screening by the screening device is between 10-20 meshes.

[0020] Furthermore, the present invention also provides a process for preparing organic compound fertilizer using the system, which specifically comprises the following steps:

[0021] 1) Mixing reaction: sodium percarbonate mother liquor flocculation precipitate and thiourea dioxide mother liquor are added into the reactor for mixing. The mixing time is 10-50 minutes and the mixing temperature is 15-20°C. The sodium percarbonate mother liquor flocculation precipitate includes sodium polyacrylate, sodium carbonate, and a small amount of activated sludge and trace elements. During the mixing process, the sodium carbonate in the sodium percarbonate mother liquor flocculation precipitate reacts with thiourea dioxide to decompose thiourea dioxide into urea and sulfate to obtain a reaction solution.

[0022] Then, furfural residue is added into the reactor, and the furfural residue is mixed with the reaction solution to form a slurry material;

[0023] 2) Granulation: The slurry material obtained in step 1) is transported to a screw granulator for extrusion granulation to obtain granular material;

[0024] 3) Coating: Adding plant ash into a coating machine, sending the pellets obtained in step 2) into the coating machine, at which time the pellets and the plant ash are rolled into balls, and the plant ash is coated outside the pellets;

[0025] 4) Screening: The powder-coated granules are sent to the screening device for screening. After screening, the granules with qualified particle size are sent to the dryer;

[0026] 5) Drying and post-processing: The qualified granular materials enter the dryer and are dried to remove moisture from the granules to obtain the final product.

[0027] Specifically, in step 1), the added amount ratio (mass ratio) of the sodium percarbonate mother liquor flocculation precipitate to the thiourea dioxide mother liquor is 1:1-5.

[0028] Specifically, the flocculated precipitate of sodium percarbonate mother liquor includes 18-20% by mass of sodium polyacrylate, 3-5% by mass of sodium carbonate, and a small amount of activated sludge (3% by mass) and trace elements (0.4% by mass).

[0029] Specifically, the thiourea dioxide mother liquor includes 25-30% by mass of ammonium bicarbonate, 1-2% by mass of urea, 2-3% by mass of thiourea dioxide and 0.2-0.5% by mass of thiourea.

[0030] Specifically, in step 1), the mass ratio of furfural residue, sodium percarbonate mother liquor flocculation precipitate, and thiourea dioxide mother liquor is 1: (0.2-0.4): (0.5-1). Specifically, the furfural residue is a solid waste residue obtained in the process of producing furfural by using biomass raw materials such as corn cobs, corn stalks, and wheat straws through processes such as crushing, dehydration, dilute acid hydrolysis, distillation, and solid-liquid separation, wherein the organic matter content can reach more than 76%; the furfural residue of the present invention is a waste residue obtained in the process of producing furfural by referring to the method in Chinese patent (CN2008101410239 Method for producing furfural by clean hydrolysis of biomass), and the organic fertilizer prepared by using furfural residue is particularly suitable for saline-alkali soil, lime soil, paddy fields, and barren land lacking organic matter, which can not only increase crop yields, but also improve soil and improve soil fertility.

[0031] Specifically, in step 3), the mass ratio of the pellets to the wood ash is 1:(0.1-0.2).

[0032] Specifically, the granular material entering the screening device is first screened by the upper screen, and the large particles are sent to the crusher for crushing, and then transported to the reactor for re-granulation; after the initial screening, the smaller particles are screened again by the lower screen and screened into larger particle size particles and smaller particle size particles. The larger particle size particles are qualified particles and are directly transported to the dryer through the pipeline, and the smaller particle size particles are directly transported to the reactor through the pipeline.

[0033] Further preferably, the size of the qualified particles is between 10-20 meshes.

[0034] Specifically, the moisture content of the product obtained in step 5) is 0.5-2%, and the yield is ≥99.5%.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] 1. The system of the present invention selects large particles and small particles through a screening device, and the large particles are sent to a crusher for re-crushing and sent to a reactor together with small particles. The screened qualified particles are sent to a dryer for direct drying, thereby improving the utilization rate of granulation.

[0037] 2. The process of the present invention utilizes the sodium carbonate in the flocculation precipitate of the sodium percarbonate mother liquor to react with thiourea dioxide to decompose thiourea dioxide into urea and sulfate, without using new sodium carbonate, thus reducing costs.

[0038] 3. The main fertility source of the prepared compound fertilizer is furfural residue, in which the organic matter content can reach more than 76%. The organic fertilizer prepared using furfural residue is particularly suitable for saline-alkali soil, lime soil, rice fields and barren land lacking organic matter. It can not only increase crop yields, but also improve soil and improve soil fertility.

[0039] 4. The process of the present invention can prevent the particles from sticking and agglomerating and increase the content of nitrogen, phosphorus, potassium, etc. in the particles by wrapping the wood ash outside the particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of the structure of the system described in Example 1;

[0041] Figure 2 This is a schematic diagram of the structure of the screening device in Example 1. DETAILED DESCRIPTION

[0042] In order to make the technical purpose, technical solution and beneficial effects of the present invention clearer, the technical solution in the embodiment of the present invention is clearly and completely described, and the described embodiment is only a part of the embodiment of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] Example 1

[0044] like Figure 1-2 As shown, a system for preparing organic compound fertilizer using waste includes a dryer 4, a crusher 5, and a reactor 1, a screw granulator 2, a powder coating machine 6 and a screening device 3 which are sequentially connected through pipelines.

[0045] The screw granulator 2 can extrude and granulate the mixed materials.

[0046] A first transfer pump is provided on the pipeline connecting the screw granulator 2 and the powder coating machine 6 , and the particles extruded by the screw granulator 2 are pressurized and fed into the powder coating machine 6 by the first transfer pump.

[0047] The powder coating machine 6 comprises a rotating drum. When in use, the materials are mixed, and then granular materials or powder materials such as plant ash and straw are added. The plant ash or straw is coated on the surface of the materials by the rotation of the rotating drum.

[0048] A second transfer pump is provided on the pipeline connecting the powder coating machine 6 and the screening device 3 ; the particles processed by the powder coating machine 6 are pressurized and sent into the screening device 3 by the second transfer pump.

[0049] An upper screen 3-1 and a lower screen 3-2 are provided in the screening device 3, and the upper screen 3-1 and the lower screen 3-2 divide the inner cavity of the screening device 3 into an upper cavity, a middle cavity and a lower cavity from top to bottom;

[0050] The inlet end of the screening device 3 is connected to the upper cavity;

[0051] The upper cavity of the screening device 3 is connected to the inlet end of the crusher 5 through a pipeline, and the outlet end of the crusher 5 is connected to the reactor 1 through a pipeline;

[0052] The middle cavity of the screening device 3 is connected to the dryer 4 through a pipeline;

[0053] The lower cavity of the screening device 3 is connected to the reactor 1 through a pipeline;

[0054] The mesh aperture of the upper mesh 3-1 is larger than the mesh aperture of the lower mesh 3-2.

[0055] Example 2

[0056] Example 2 provides a process for preparing organic compound fertilizer using the system described in Example 1, which specifically includes the following steps:

[0057] 1) Mixing reaction: sodium percarbonate mother liquor flocculation precipitate and thiourea dioxide mother liquor are added to reactor 1 for mixing, the mixing time is 30 minutes, and the mixing temperature is 15-20°C (since the temperature of the sodium percarbonate mother liquor obtained after production is 20-25°C, and the temperature of the thiourea dioxide mother liquor is 3-5°C, after the two are mixed, the high temperature will be neutralized with the low temperature to reach an average temperature, and the temperature after the high temperature and low temperature are neutralized will also change with the different ratios of the two and the different mixing times, but the minimum is not less than 3°C and the maximum is not higher than 60°C; because below 3°C, the reaction activity of thiourea dioxide is too low, and above 60°C, urea will be decomposed in the solution, and the purpose of producing organic fertilizer will not be achieved). During the mixing process, the sodium carbonate in the sodium percarbonate mother liquor flocculation precipitate reacts with thiourea dioxide, and the thiourea dioxide is decomposed into urea and sulfate to obtain a reaction solution;

[0058] The flocculated precipitate of sodium percarbonate mother liquor includes 20% sodium polyacrylate, 5% sodium carbonate, and a small amount of activated sludge (3% by mass) and trace elements (0.4% by mass).

[0059] The thiourea dioxide mother liquor includes 30% by mass of ammonium bicarbonate, 2% by mass of urea, 3% by mass of thiourea dioxide and 0.5% by mass of thiourea;

[0060] Then, furfural residue is added to the reactor 1, and the furfural residue is mixed with the reaction solution to form a slurry material, wherein the mass ratio of furfural residue, sodium percarbonate mother liquor flocculation precipitate, and thiourea dioxide mother liquor is 1: (0.2-0.4): (0.5-1);

[0061] The furfural residue is a solid waste residue obtained in the process of producing furfural by using biomass raw materials such as corn cobs, corn stalks, and wheat straws through processes such as crushing, dehydration, dilute acid hydrolysis, distillation, and solid-liquid separation, wherein the organic matter content can reach more than 76%; the furfural residue of the present invention is a waste residue obtained in the process of producing furfural by referring to the method in Chinese patent (CN2008101410239 Method for producing furfural by clean hydrolysis of biomass), and the organic fertilizer prepared by using the furfural residue is particularly suitable for saline-alkali soil, lime soil, paddy fields, and barren land lacking organic matter, and can not only increase crop yield, but also improve soil and improve soil fertility;

[0062] 2) Granulation: The slurry material obtained in step 1) is transported to a screw granulator 2 for extrusion granulation to obtain granular material;

[0063] 3) Coating: Adding plant ash into a coating machine 6, sending the pellets obtained in step 2) into the coating machine 6, at this time, the pellets and the plant ash are rolled into balls, and the plant ash is coated on the outside of the pellets, wherein the mass ratio of the pellets to the plant ash is 1:(0.1-0.2). By coating the plant ash on the outside of the pellets, it is possible to prevent the particles from sticking and agglomerating and to increase the content of nitrogen, phosphorus, potassium, etc. in the particles;

[0064] The reaction between plant ash and sodium polyacrylate in the pulp material will generate metal salts of polyacrylic acid, mainly calcium polyacrylate and potassium polyacrylate. Calcium polyacrylate is a commonly used water-absorbing resin with strong moisture retention.

[0065] 4) Screening: The powder-coated granular material is sent to the screening device 3 for screening;

[0066] The granular material entering the screening device 3 is first screened by the upper screen 3-1, and the large particles are sent to the crusher 5 for crushing, and then transported to the reactor 1 for re-granulation; the smaller particles after the initial screening are screened again by the lower screen 3-2 and screened into larger particle size particles and smaller particle size particles. The larger particle size particles are qualified particles and are directly transported to the dryer 4 through the pipeline, and the smaller particle size particles are directly transported to the reactor 1 through the pipeline;

[0067] The size of the qualified particles is between 10-20 meshes;

[0068] 5) Drying and post-processing: The qualified granular materials entering the dryer 4 are dried to remove the moisture in the granules to obtain the final product;

[0069] The moisture content of the final product will be tested to be 0.5-2%; the output of the final product is determined by the moisture in materials such as sodium percarbonate mother liquor, thiourea dioxide mother liquor and furfural residue. After removing the moisture, the output is about 75% of the input of all materials. Since all materials (including moisture) in the obtained product can be used as fertilizers, but a small amount of loss is inevitable, the yield is ≥99.5%, close to 100%, and almost all of it is usable.

[0070] The process for preparing the organic compound fertilizer of the present invention utilizes the sodium carbonate in the flocculation precipitate of the sodium percarbonate mother liquor to react with thiourea dioxide to decompose the thiourea dioxide into urea and sulfate, and does not need to use new sodium carbonate, thereby reducing the cost.

[0071] In summary, the system of the present invention has a simple structure and high reliability. The process of preparing organic compound fertilizer using the system can achieve effective recycling of waste (wood ash, sodium percarbonate mother liquor, furfural residue), which not only improves the utilization rate of raw materials, but also has the effect of energy saving and environmental protection.

[0072] In the description of the present invention, it should be noted that directional words, such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like, indicating directions and positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and cannot be understood as limiting the specific scope of protection of the present invention.

[0073] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged in appropriate circumstances, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, the process, method, system, product or equipment comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0074] Finally, it should be noted that the above are only preferred embodiments of the present invention and the principles of the application technology. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention is described in more detail through the above embodiments, the present invention is not limited to the specific embodiments described herein, and may include more other effective embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A process for preparing organic compound fertilizer, characterized in that: The process is realized by a system for preparing organic compound fertilizer using waste; The system comprises a dryer, a crusher, and a reactor, a screw granulator, a powder coating machine and a screening device which are sequentially connected through pipelines; An upper screen and a lower screen are provided in the screening device, and the upper screen and the lower screen separate the inner cavity of the screening device from top to bottom into an upper cavity, a middle cavity and a lower cavity; The inlet end of the screening device is connected to the upper cavity; The upper cavity of the screening device is connected to the inlet end of the crusher through a pipeline, and the outlet end of the crusher is connected to the reactor through a pipeline; The middle cavity of the screening device is connected to the dryer through a pipeline; The lower cavity of the screening device is connected to the reactor through a pipeline; The mesh aperture of the upper mesh is larger than the mesh aperture of the lower mesh; The process comprises the following steps: 1) Mixing reaction: adding sodium percarbonate mother liquor flocculation precipitate and thiourea dioxide mother liquor into a reactor and mixing them for 10-50 min at a mixing temperature of 15-20° C. to obtain a reaction solution; Then, furfural residue is added into the reactor, and the furfural residue is mixed with the reaction solution to form a slurry material; 2) Granulation: The slurry material obtained in step 1) is transported to a screw granulator for extrusion granulation to obtain granular material; 3) Coating: Adding plant ash into a coating machine, sending the pellets obtained in step 2) into the coating machine, at which time the pellets and the plant ash are rolled into balls, and the plant ash is coated outside the pellets; 4) Screening: The powder-coated granules are sent to the screening device for screening. After screening, the granules with qualified particle size are sent to the dryer; 5) Drying and post-processing: The qualified granular materials enter the dryer and are dried to remove moisture from the granules to obtain the final product.

2. The process according to claim 1, characterized in that A first delivery pump is arranged on the pipeline connecting the screw granulator and the powder coating machine, and the particles extruded by the screw granulator are pressurized and delivered to the powder coating machine through the first delivery pump.

3. The process according to claim 1, characterized in that A second conveying pump is arranged on the pipeline connecting the powder coating machine and the screening device; the particles processed by the powder coating machine are pressurized and sent to the screening device through the second conveying pump.

4. The process according to claim 1, characterized in that In step 1), the mass ratio of the sodium percarbonate mother liquor flocculation precipitate to the thiourea dioxide mother liquor is 1:1-5.

5. The process according to claim 1, characterized in that In step 1), the mass ratio of furfural residue, sodium percarbonate mother liquor flocculation precipitate, and thiourea dioxide mother liquor is 1: (0.2-0.4): (0.5-1).

6. The process according to claim 1, characterized in that In step 3), the mass ratio of pellets to wood ash is 1:(0.1-0.2).

7. The process according to claim 1, characterized in that The granular material entering the screening device is first screened by the upper screen, and the large particles are sent to the crusher for crushing, and then transported to the reactor for re-granulation; after the initial screening, the smaller particles are screened again by the lower screen and screened into larger particles and smaller particles. The larger particles are qualified particles and are directly transported to the dryer through the pipeline, and the smaller particles are directly transported to the reactor through the pipeline.

8. The process according to claim 1, characterized in that The size of the qualified particles is between 10-20 meshes.

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