Granular fertilizer step-by-step efficient granulation production process

Abstract

The invention relates to the technical field of granular fertilizer production, in particular to a granular fertilizer step-by-step efficient granulation production process which comprises the following steps: S10) extrusion granulation: performing extrusion molding on a material with the water content of 18-30% by adopting an extrusion granulator to obtain material granules; s20) steam softening: conveying the material particles to a rotary drum granulator, and introducing steam for softening to obtain softened material particles; s30) bonding and surface modification treatment: spraying a binder to bond surface gaps of the material particles, and modifying surface pits and corners; s40) low-temperature drying: drying in a granulating and drying all-in-one machine with hot air at 150-250 DEG C until the water content is less than or equal to 12%; and S50) post-treatment: cooling, screening, anti-hardening agent spraying and polishing. The method is suitable for producing granular fertilizer by taking sugarcane filter mud, sugarcane alcohol fermentation liquor, silkworm excrement, excrement and the like as raw materials, and compared with a single-drum normal-temperature granulation comparison process, the method has the advantages that the production efficiency of the granular fertilizer is improved by 30-80%, the quality of the granular fertilizer is improved, and the material returning rate and the drying energy consumption are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of granular fertilizer production, and particularly relates to a step-by-step high-efficiency granulation production process for granular fertilizers. Background Art

[0002] In the production process of organic fertilizers, granulation is a key step. Traditional granulation processes often have problems such as low granulation efficiency, high energy consumption, irregular particle shapes, and high return rates.

[0003] In related technologies, the Chinese invention application with the publication number CN108484260B discloses a method for improving the backward production capacity of sugarcane filter mud fertilizer by using a drum granulation process. The present invention discloses a method for improving the backward production capacity of sugarcane filter mud fertilizer by using a drum granulation process, including the following steps: (1) formulating a functional equation for fertilizer production capacity, the inner diameter of the drum granulator, and the inner diameter and height of the granulation and drying integrated machine; (2) setting the fertilizer production capacity target, and respectively calculating the inner diameter of the drum granulator and the inner diameter and height of the granulation and drying integrated machine according to the functional equation; (3) selecting equipment with suitable models, specifications, and materials according to the calculated inner diameter of the drum granulator and the inner diameter and height of the granulation and drying integrated machine; (4) formulating a raw material formula and adding sugarcane alcohol fermentation concentrate as a binder; (5) conducting production debugging to determine the optimal operating parameters. The method of the present invention can be used to produce organic fertilizers, bio-organic fertilizers, and organic-inorganic compound fertilizers mainly composed of sugarcane filter mud. By increasing the inner diameter specifications of key supporting equipment (drum granulator, granulation and drying integrated machine) and reducing the rotation speed, the fertilizer production capacity can be improved. At the same time, by adding sugarcane alcohol fermentation concentrate as a binder, the fertilizer ball forming rate and production capacity can be improved, the fertilizer efficiency is high, and the crop yield increase is significant. However, its granulation process using the inner diameter of the drum granulator, granulation and drying integrated machine + normal temperature granulation + sugarcane alcohol fermentation concentrate as a binder still has problems such as low granulation efficiency, high energy consumption, irregular particle shapes, and high return rates. Summary of the Invention

[0004] In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide a step-by-step high-efficiency granulation production process for granular fertilizers, which can improve granulation efficiency and particle quality, and reduce energy consumption and return rate.

[0005] The purpose of the present invention is achieved by adopting the following technical solutions:

[0006] The present invention provides a step-by-step high-efficiency granulation production process for granular fertilizers, which sequentially includes the following steps:

[0007] S10) Extrusion granulation: Using an extrusion granulator to extrude the material with a water content of 18%-30% into a shape, obtaining round or oval material particles;

[0008] S20) Steam softening: Transport the material particles to a drum granulator, introduce steam into the drum granulator for softening to obtain softened material particles;

[0009] S30) Bonding and surface modification treatment: Spray a binder to bond the surface gaps of the material particles, and modify the surface pits and corners to make the particles tighter and smoother;

[0010] S40) Low-temperature drying: Dry with hot air at 150 - 250 °C in a granulation and drying integrated machine until the water content ≤ 12%;

[0011] S50) Post-treatment: Includes cooling, screening, spraying of anti-caking agent and polishing.

[0012] In the first aspect of the present invention, as an alternative embodiment, in step S10, multi-unit parallel operation is adopted, the power of a single extrusion granulator is 15 - 22 kW, and the total production capacity ≥ 12 t / h.

[0013] In the first aspect of the present invention, as an alternative embodiment, in step S10, the main shaft speed of the extrusion granulator is 460 - 500 rpm, and the forming pressure of the material particles is 25 - 32 kPa.

[0014] In the first aspect of the present invention, as an alternative embodiment, in step S20, the steam temperature is 180 - 220 °C, and the steam pressure is maintained at 0.6 - 1.0 MPa.

[0015] In the first aspect of the present invention, as an alternative embodiment, in step S20, the drum machine speed is 8 - 13 rpm.

[0016] In the first aspect of the present invention, as an alternative embodiment, in step S30, the binder is sugarcane alcohol fermentation broth with a concentration of 58 - 62 BX°, and the spraying amount is 3% - 5%;

[0017] In the first aspect of the present invention, as an alternative embodiment, in step S30, the binder is a thiourea hot solution, and the weight ratio of urea, water and concentrated sulfuric acid in the thiourea hot solution is (3.0 - 3.5):1:1, heated to 75 - 85 °C, and the spraying amount is 1% - 3%.

[0018] In the first aspect of the present invention, as an alternative embodiment, in step S50, the material is transported to a cooler, and natural air is blown in for cooling.

[0019] In the first aspect of the present invention, as an alternative embodiment, in step S50, the top sieve for screening has a sieve hole diameter of 5.0 mm, and the bottom sieve has a sieve hole diameter of 2.5 mm.

[0020] In the first aspect of the present invention, as an alternative embodiment, in step S50, the anti-caking agent is a natural polymer, and the addition amount is 0.2-0.5%; the rotation speed of the polishing machine is 8-10 rpm.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] By adjusting the water content of the material within a preset range, the present invention can quickly form round or oval material particles with an extrusion granulator. Spraying steam into the drum granulator can quickly soften the material particles, spraying a binder to bond the gaps of the material particles, and modifying the pits and corners on the surface to make the particles more compact and smoother. The hot air of the dryer dries the material particles. The high temperature of the steam and the binder increases the temperature of the material particles, greatly reducing the hot air temperature in the dryer, reducing energy consumption. The extrusion granulator greatly reduces the return rate, and the overall supporting technology greatly improves the production efficiency of granular fertilizer. Thus, through step-by-step processing, the present invention makes the granulation process more efficient and stable, improving the production efficiency of granular fertilizer; through steam softening and bonding treatment, it improves the appearance and viscosity of granular fertilizer, making it more round, smoother, and brighter; the low-temperature drying technology reduces energy consumption and improves the economic benefits of production; the overall solution reduces the return rate and reduces waste in the production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a process flow diagram of the process of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] Next, in combination with the drawings and specific embodiments, the present invention will be further described. It should be noted that, on the premise of no conflict, the following-described embodiments or technical features can be arbitrarily combined to form new embodiments. Except as otherwise specified, the materials and equipment used in this embodiment can be purchased from the market.

[0025] Please refer to Figure 1 , the first aspect of the present invention provides a step-by-step high-efficiency granulation production process for granular fertilizer, which sequentially includes the following steps:

[0026] S10) Extrusion granulation: Using an extrusion granulator to extrude a material with a water content of 18%-30% into a shape, obtaining round or oval material particles;

[0027] S20) Steam softening: Transporting the material particles to a drum granulator, and introducing steam into the drum granulator for softening to obtain softened material particles;

[0028] S30) Bonding and surface modification treatment: Spray binder into the gaps on the surface of the material particles for bonding, and modify the surface pits and corners to make the particles more compact and rounder.

[0029] S40) Low-temperature drying: In the granulation and drying integrated machine, dry with hot air at 150 - 250 °C until the water content ≤ 12%; preferably, the granulation and drying integrated machine uses biomass fuel.

[0030] S50) Post-treatment: Including cooling, screening, spraying anti-caking agent and polishing.

[0031] On the basis of the above solutions, the present invention can quickly form round or oval material particles by an extrusion granulator by adjusting the water content of the material within a preset range. Spraying steam into the rotary drum granulator can quickly soften the material particles. Spray binder to bond the gaps of the material particles and modify the surface pits and corners to make the particles more compact and rounder. The hot air of the dryer dries the material particles. The high temperature of the steam and the binder increases the temperature of the material particles, greatly reducing the hot air temperature in the dryer, reducing energy consumption. The extrusion granulator greatly reduces the return rate, and the overall supporting technology greatly improves the production efficiency of granular fertilizer. Thus, through step-by-step treatment, the present invention makes the granulation process more efficient and stable, improving the production efficiency of granular fertilizer; through steam softening and bonding treatment, it improves the appearance and viscosity of granular fertilizer, making it more round, smooth and shiny; the low-temperature drying technology reduces energy consumption and improves the economic benefits of production; the overall solution reduces the return rate and reduces waste in the production process.

[0032] As a preferred embodiment, in step S10, multi-unit parallel operation is adopted, the power of a single extrusion granulator is 15 - 22 kW, and the total production capacity ≥ 12 t / h.

[0033] Thus, through multi-unit parallel operation (single unit 15 - 22 kW, total production capacity ≥ 12 t / h) of the present invention, the large-scale production demand is met.

[0034] As a preferred embodiment, in step S10, the main shaft speed of the extrusion granulator is 460 - 500 rpm, and the forming pressure is 25 - 32 kPa.

[0035] Thus, with the main shaft speed of 460 - 500 rpm and the forming pressure of 25 - 32 kPa of the present invention, it ensures uniform particle size and consistent density. In addition, through power and speed optimization, high-efficiency extrusion forming under low energy consumption is achieved.

[0036] As a preferred embodiment, in step S20, the steam temperature is 180 - 220 °C, and the steam pressure is maintained at 0.6 - 1.0 MPa.

[0037] Thus, the steam of the present invention has a temperature of 180 - 220 °C and a pressure of 0.6 - 1.0 MPa, which rapidly penetrates into the interior of the particles and shortens the softening time. Moderate softening opens the micropores on the particle surface, facilitating the subsequent penetration of the binder and enhancing the bonding effect. It avoids the melting or caking of the particles caused by too high temperature while ensuring the softening effect.

[0038] In the first aspect of the present invention, as an alternative embodiment, in step S20, the rotational speed of the drum is 8 - 13 rpm. Thus, the low rotational speed ensures sufficient contact between the particles and the steam, avoiding the breakage of the particles caused by excessive centrifugal force.

[0039] As a preferred embodiment, in step S30, the binder is a sugarcane alcohol fermentation broth with a concentration of 58 - 62 BX°, and the spraying amount is 3% - 5%;

[0040] Thus, components such as polysaccharides and proteins in the fermentation broth provide strong bonding force and improve the particle compactness. Using agricultural waste (bagasse) to produce the fermentation broth reduces costs and pollution. The high - concentration (58 - 62 BX°) fermentation broth can fill the micropores on the particle surface and improve the smoothness.

[0041] As a preferred embodiment, in step S30, the binder is a thiourea hot solution, and the weight ratio of urea, water, and concentrated sulfuric acid in the thiourea hot solution is (3.0 - 3.5):1:1. It is heated to 75 - 85 °C, and the spraying amount is 1% - 3%.

[0042] Thus, thiourea reacts with urea to form urea - formaldehyde resin, providing strong bonding force and enhancing the water resistance of the particles. Heating at 75 - 85 °C promotes the reaction, avoiding the decomposition of the solution or the discoloration of the particles caused by high temperature. The low spraying amount (1% - 3%) reduces waste and ensures that the binder evenly covers the particle surface.

[0043] As a preferred embodiment, in step S50, the material is conveyed to a cooler, and natural air is blown in for cooling. The present invention cools through natural air, preventing the particles from cracking or caking due to sudden cooling. It does not require additional energy consumption and reduces production costs.

[0044] As a preferred embodiment, in step S50, the top sieve for screening has a sieve hole diameter of 5.0 mm, and the bottom sieve has a sieve hole diameter of 2.5 mm. The present invention precisely screens out qualified particles (2.5 - 5.0 mm), eliminates too large or too small particles, and improves the product uniformity. It avoids unqualified particles from entering the subsequent processes and reduces production waste.

[0045] As a preferred embodiment, in step S50, the anti - caking agent is a natural polymer, and the addition amount is 0.2 - 0.5%; the rotational speed of the polishing machine is 8 - 10 rpm. The low - speed polishing of the present invention removes the burrs and edges of the particles, increasing the gloss and smoothness.

[0046] The following are some embodiments listed in this application, and this application will be further described through the following embodiments.

[0047] Examples 1 - 3:

[0048] A certain enterprise installed a production line with 32 extrusion granulators (total production capacity reaching 25.6 t / h), 1 drum granulator (inner diameter height of 2.3 m, total production capacity reaching 24 t / h), 1 drying and granulating integrated machine, 1 cooler, 1 polishing machine, etc. for the production of Type I organic-inorganic compound fertilizer (12 - 4 - 8, OM≥20%).

[0049] Table 1 is the raw material formula table of Type I organic-inorganic compound fertilizer (12 - 4 - 8, OM≥20%).

[0050] Table 1

[0051]

[0052] Example 1:

[0053] A step-by-step high-efficiency granulation production process for granular fertilizer, which successively includes the following steps:

[0054] S10) Extrusion granulation: Using an extrusion granulator to extrude the material with a water content of 20% - 25% into a formed shape to obtain round or oval material particles;

[0055] S20) Steam softening: Transporting the material particles to a drum granulator, and introducing steam at 190°C and a pressure of 0.7 Mpa into the drum granulator for softening to obtain softened material particles;

[0056] S30) Bonding and surface modification treatment: Spraying a binder to bond the surface gaps of the material particles and modify the surface pits and edges; the binder is a thiourea hot solution, and the weight ratio of urea, water and concentrated sulfuric acid in the thiourea hot solution is 3.0:1:1, heated to 75°C, and the spraying amount is 1%.

[0057] S40) Low-temperature drying: Drying with hot air at 200°C generated by biomass fuel in the granulation and drying integrated machine until the water content ≤ 12%;

[0058] S50) Post-treatment: Including cooling, screening, spraying of anti-caking agent and polishing. After passing the inspection, the product of Type I organic-inorganic compound fertilizer (12 - 4 - 8, OM≥20%) is obtained.

[0059] Example 2:

[0060] A step-by-step high-efficiency granulation production process for granular fertilizer, which successively includes the following steps:

[0061] S10) Extrusion granulation: Using an extrusion granulator to extrude the material with a water content of 20%-25% into a shape, obtaining round or oval material particles;

[0062] S20) Steam softening: Transporting the material particles to a drum granulator, and introducing steam at 200°C and a pressure of 0.8 Mpa into the drum granulator for softening to obtain softened material particles;

[0063] S30) Bonding and surface modification treatment: Spraying a binder to bond the surface gaps of the material particles and modify the surface pits and edges; the binder is a thiourea hot solution, and the weight ratio of urea, water and concentrated sulfuric acid in the thiourea hot solution is 3.2:1:1, heated to 80°C, and the spraying amount is 2%.

[0064] S40) Low-temperature drying: Drying in a granulation and drying integrated machine with hot air generated by biomass fuel at 220°C until the water content ≤ 12%;

[0065] S50) Post-treatment: Including cooling, screening, spraying of anti-caking agent and polishing. After passing the inspection, obtaining the product of type I organic-inorganic compound fertilizer (12-4-8, OM≥20%).

[0066] Example 3:

[0067] A step-by-step high-efficiency granulation production process for granular fertilizer, successively including the following steps:

[0068] S10) Extrusion granulation: Using an extrusion granulator to extrude the material with a water content of 20%-25% into a shape, obtaining round or oval material particles;

[0069] S20) Steam softening: Transporting the material particles to a drum granulator, and introducing steam at 210°C and a pressure of 0.9 Mpa into the drum granulator for softening to obtain softened material particles;

[0070] S30) Bonding and surface modification treatment: Spraying a binder to bond the surface gaps of the material particles and modify the surface pits and edges; the binder is a thiourea hot solution, and the weight ratio of urea, water and concentrated sulfuric acid in the thiourea hot solution is 3.5:1:1, heated to 85°C, and the spraying amount is 3%.

[0071] S40) Low-temperature drying: Drying in a granulation and drying integrated machine with hot air generated by biomass fuel at 250°C until the water content ≤ 12%;

[0072] S50) Post-treatment: Including cooling, screening, spraying of anti-caking agent and polishing. After passing the inspection, obtaining the product of type I organic-inorganic compound fertilizer (12-4-8, OM≥20%).

[0073] Examples 4-6

[0074] In order to produce Type II organic-inorganic compound fertilizer (10-5-15, OM≥15%), a certain enterprise has an ingredient formula table as shown in Table 2 and has installed a production line with 30 extrusion granulators (with a total production capacity of 24 t / h), 1 rotary drum granulator (inner diameter height of 2.2 m, total production capacity of 23 t / h), 1 integrated drying and granulating machine, 1 cooler, 1 polishing machine, etc., and uses the process of the present invention to produce granular fertilizer.

[0075] Table 2 is the ingredient formula table of Type II organic-inorganic compound fertilizer (10-5-15, OM≥15%).

[0076] Table 2

[0077]

[0078] Example 4:

[0079] A step-by-step high-efficiency granulation production process for granular fertilizer successively includes the following steps:

[0080] S10) Extrusion granulation: Using an extrusion granulator to extrude the material with a water content of 18%-20% into round or oval material particles;

[0081] S20) Steam softening: Transporting the material particles to a rotary drum granulator and introducing steam at 180°C and a pressure of 0.6 Mpa into the rotary drum granulator for softening to obtain softened material particles;

[0082] S30) Bonding and surface modification treatment: Spraying a binder to bond the surface gaps of the material particles and modify the surface pits and edges; the binder is sugarcane alcohol fermentation broth with a concentration of 58 BX° and a dosage of 3% of the material weight;

[0083] S40) Low-temperature drying: Drying with hot air at 150°C generated by biomass fuel in the integrated granulation and drying machine until the water content ≤12%;

[0084] S50) Post-treatment: Including cooling, screening, spraying of anti-caking agent and polishing. After passing the inspection, the product of Type II organic-inorganic compound fertilizer (10-5-15, OM≥15%) is obtained.

[0085] Example 5:

[0086] A step-by-step high-efficiency granulation production process for granular fertilizer successively includes the following steps:

[0087] S10) Extrusion granulation: Using an extrusion granulator to extrude the material with a water content of 18%-20% into round or oval material particles;

[0088] S20) Steam softening: The material particles are transported to a drum granulator, and steam at 190 °C and a pressure of 0.7 Mpa is introduced into the drum granulator for softening to obtain softened material particles;

[0089] S30) Bonding and surface modification treatment: A binder is sprayed to bond the surface gaps of the material particles and modify the surface pits and corners; the binder is a sugarcane alcohol fermentation broth with a concentration of 60 BX° and a dosage of 4% of the material weight;

[0090] S40) Low-temperature drying: In a granulation and drying integrated machine, hot air at 180 °C generated by biomass fuel is used for drying until the water content ≤ 12%;

[0091] S50) Post-treatment: It includes cooling, screening, anti-caking agent spraying and polishing. After passing the inspection, a type II organic-inorganic compound fertilizer (10-5-15, OM ≥ 15%) product is obtained.

[0092] Example 6:

[0093] A step-by-step high-efficiency granulation production process for granular fertilizer successively includes the following steps:

[0094] S10) Extrusion granulation: Using an extrusion granulator to extrude the material with a water content of 18% - 20% into shaped particles, obtaining round or oval material particles;

[0095] S20) Steam softening: The material particles are transported to a drum granulator, and steam at 200 °C and a pressure of 0.8 Mpa is introduced into the drum granulator for softening to obtain softened material particles;

[0096] S30) Bonding and surface modification treatment: A binder is sprayed to bond the surface gaps of the material particles and modify the surface pits and corners; the binder is a sugarcane alcohol fermentation broth with a concentration of 62 BX° and a dosage of 5% of the material weight;

[0097] S40) Low-temperature drying: In a granulation and drying integrated machine, hot air at 200 °C generated by biomass fuel is used for drying until the water content ≤ 12%;

[0098] S50) Post-treatment: It includes cooling, screening, anti-caking agent spraying and polishing. After passing the inspection, a type II organic-inorganic compound fertilizer (10-5-15, OM ≥ 15%) product is obtained.

[0099] Comparative Example 1: Install an organic-inorganic compound fertilizer production line such as a drum granulator (inner diameter height is 2.3 m, total production capacity reaches 24 t / h), a drying and granulation integrated machine, a coolant, a screening machine, an anti-caking agent spraying machine, a polishing machine, etc. Adopt a single drum and normal temperature granulation technology and hot gas from coal combustion as the drying energy to produce a type I organic-inorganic compound fertilizer (12-4-8, OM ≥ 20%).

[0100] Comparative Example 2: An organic-inorganic compound fertilizer production line equipped with a rotary drum granulator (inner diameter height of 2.2 m, total production capacity of 23 t / h), a drying and granulating integrated machine, a coolant, a screening machine, an anti-caking agent spraying machine, a polishing machine, etc. Type II organic-inorganic compound fertilizer (10-5-15, OM≥15%) is produced using a single rotary drum and room temperature granulation technology and hot gas from coal combustion as the drying energy source.

[0101] Performance testing:

[0102] The processes of Examples 1-6 were compared with those of Comparative Examples 1-2. The specific comparison results are shown in Table 3.

[0103] Table 3

[0104]

[0105]

[0106] The above embodiments are only the preferred embodiment modes of the present invention and cannot be used to limit the protection scope of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention fall within the protection scope required by the present invention.

Claims

1. A step-by-step high-efficiency granulation production process for granular fertilizer, characterized in that, The following steps are included in sequence: S10) extrusion granulation: using an extrusion granulator to extrude the material with a moisture content of 18%-30% to obtain round or oval material particles; S20) steam softening: conveying the material particles to a drum granulator, introducing steam into the drum granulator for softening, and obtaining softened material particles; S30) Bonding and surface modification: spraying a bonding agent to bond the gaps on the surface of the material particles, and modifying the surface pits and corners to make the particles more compact and smoother; S40) low temperature drying: drying in a granulation and drying machine with hot air at 150-250°C until the moisture content is ≤12%; S50) Post-processing: including cooling, screening, anti-caking agent spraying and polishing.

2. The step-by-step high-efficiency granulation production process of the granular fertilizer according to claim 1, characterized in that, In step S10, multiple extrusion granulation machines are used to operate in parallel, the power of a single extrusion granulation machine is 15-22 kilowatts, and the total capacity is ≥12 t / h.

3. The step-by-step high-efficiency granulation production process of granular fertilizer according to claim 1, characterized in that, In step S10, the main shaft speed of the extrusion granulator is 460-500 rpm, and the material particle forming pressure is 25-32 kPa.

4. The step-by-step high-efficiency granulation production process of granular fertilizer according to claim 1, characterized in that, In step S20, the steam temperature is 180-220°C, and the steam pressure is maintained at 0.6-1.0 MPa.

5. The step-by-step high-efficiency granulation production process of the granular fertilizer according to claim 1, characterized in that, In step S20, the rotation speed of the drum granulator is 8-13 rpm.

6. The step-by-step high-efficiency granulation production process of granular fertilizer according to claim 1, characterized in that, In step S30, the binder is sugarcane alcohol fermentation liquid with a concentration of 58-62BX° and a spraying amount of 3%-5%.

7. The step-by-step high-efficiency granulation production process of the granular fertilizer according to claim 1, characterized in that, In step S30, the binder is a hot thiourea solution, the weight ratio of urea, water and concentrated sulfuric acid in the hot thiourea solution is (3.0-3.5):1:1, heated to 75-85°C, and the spraying amount is 1%-3%.

8. The step-by-step high-efficiency granulation production process of the granular fertilizer according to claim 1, wherein, In step S50, the material is transported to a cooler and cooled by blowing natural wind; the top screen of the screening is a screen hole with a diameter of 5.0 mm, and the bottom screen is a screen hole with a diameter of 2.5 mm.

9. The step-by-step high-efficiency granulation production process of the granular fertilizer according to claim 1, characterized in that, In step S50, the anti-caking agent is a natural high molecular polymer, the addition amount is 0.2-0.5%, and the polishing machine speed is 8-10rpm.

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