CN114009177B

CN114009177B - High-rate pelleting coating material for small-particle seeds and coating method thereof

Info

Publication number: CN114009177B
Application number: CN202111281702.8A
Authority: CN
Inventors: 龙正柏; 朱德新; 黄岩; 韩庆辉
Original assignee: Beijing Baiqingyuan Animal Husbandry Technology Development Co ltd; Beijing Wanchengyuan Agricultural Technology Co ltd
Current assignee: Beijing Baiqingyuan Animal Husbandry Technology Development Co ltd; Beijing Wanchengyuan Agricultural Technology Co ltd
Priority date: 2021-11-01
Filing date: 2021-11-01
Publication date: 2022-11-08
Anticipated expiration: 2041-11-01
Also published as: CN114009177A

Abstract

The invention provides a high-rate pelleting coating material for small-particle seeds and a coating method thereof. The coating material comprises: fillers, binders, adjuvants, colorants and functional auxiliaries; the filler is a mixture obtained by mixing 100 parts by weight of 200-325-mesh vermiculite powder as a base material, 2-10 parts by weight of potassium carbonate, 0-15 parts by weight of bentonite and 0-20 parts by weight of diatomite by a high-speed mixer; the adhesive is a mixture which is prepared by mixing and stirring 1-3 parts by weight of high-viscosity hydroxypropyl methyl cellulose aqueous solution with the concentration of 3wt%, 1-3 parts by weight of sodium polyacrylate aqueous solution with the concentration of 7wt%, 3-5 parts by weight of polyvinyl alcohol aqueous solution with the concentration of 8wt% and 10-15 parts by weight of water at the temperature of 20-40 ℃ until emulsification; the auxiliary agent comprises 200 meshes of talcum powder and a film-forming agent, and the mass ratio is 1:1; the functional auxiliary agent comprises one or a combination of microbial fertilizer, trace element fertilizer and water retention agent. The invention solves the problems that the large-magnification pelleting of small-particle seeds is difficult or the pelleting effect is not good and the seed bud rate is influenced.

Description

High-rate pelleting coating material for small-particle seeds and coating method thereof

Technical Field

The invention relates to the field of agricultural seedling culture, in particular to a high-rate pelleting coating material for small-particle seeds and a coating method thereof.

Background

The seed pelleting coating is a seed treatment technology commonly adopted in developed countries, and is a high and new technology for seed treatment, which is realized by a coating machine/dryer and integrates multiple disciplinary achievements into a whole, wherein seeds are taken as cores, inert materials are taken as main auxiliary materials, adhesive is taken as auxiliary materials, and meanwhile, a proper amount of beneficial components such as trace fertilizer, insecticide and antibacterial agent are added. The method changes the shape of the seeds of the crops from irregular and tiny shapes into spheres with uniform size and regular shape, so that the crops which are not suitable for mechanical sowing realize precision sowing, plant protection before sowing and disease and pest control, and provides micro-fertilizer for the early growth stage of the crops to promote the growth of the crops and improve and enhance the stress resistance of the seeds.

The application of the seed pelleting and coating technology is closely related to the development of seeding machinery, particularly precision seeding machinery, because the level of agricultural machinery in China has larger difference compared with that in developed countries, particularly the difference on the precision seeding machinery is larger, the proportion of the seed pelleting application is lower, along with the transfer of a large number of rural population in China to non-agricultural industry, the requirements of large-scale and mechanization of agriculture are more and more urgent, and the pelleting effect of pelleted seeds, particularly small-particle seeds, is increasingly enhanced.

The main problems existing in the seed pelleting sowing technology in China at present are as follows:

1. at present, the seed pelleting technology at home and abroad is mainly and intensively applied to cotton, beet, vegetables, flowers and grass seeds (alfalfa), the pelleting technology is also commonly applied, the pelleting processing equipment also realizes commercialization, automation, standardization and serialization, and the development is directed to intellectualization, refinement and excellence. However, there are some problems to be further solved in the small-sized seeds, such as insufficient drying or excessive drying in the pelleting process of the high-rate pelleted seeds, uneven moisture content after pelleting treatment, severe shortening of the shelf life of the seeds, and even influence on the germination rate of the seeds.

2. The small-particle seed pelleting degree is low: the small-particle seeds are seeds with extremely small particle size and extremely low thousand seed weight, and are common in agriculture, lettuce, mustard, amaranth, celery, tobacco leaves of vegetable seeds, alfalfa, bermuda grass and the like in pasture belong to small-particle seeds, for example, the thousand seed weight of decapsulated bermuda grass is only about 0.28 g, the thousand seed weight of celery seeds is 0.4-0.6 g, the thousand seed weight of lettuce seeds is 0.5-1.2 g, and the tobacco seeds are lower to about 0.07 g.

3. Because the small-sized seeds are small in size and poor in tolerance, the membrane coating by using a bactericide or adding a fertilizer is easy to cause phytotoxicity, and the phytotoxicity of the pesticide to the seeds and seedlings is prevented by the shielding effect of the pellet coating of the seeds; in addition, chemical substances and biological substances which promote the growth of roots and seedlings can be added into the pill coating to play a role in improving the quality of the seedlings and the like, so that the research of pelleting coating is paid attention by people.

4. The adhesive used in the existing pelleting coating mainly comprises water-soluble adhesive such as starch, hydroxymethyl cellulose, sodium alginate, gelatin, arabic gum and the like, the filling material mainly comprises diatomite, kaolin, talcum powder, calcium sulfate, peat soil and the like, and the pelleting coating adopts a coating method as follows: the seeds are put into a coating container, a binder solution is sprayed on the surfaces of the seeds while the container is rotated, then a powder material is put into the container to combine the powder material with the seeds, and the operations are repeated until the particle size of the pelletized seeds reaches the expected thickness. However, the use of the adhesive and the material powder ensures that the pelleting forming time is longer, the general time is 1 to 2 hours, and the pelleting coating is easy to crack under the natural condition; the pelleted seeds are high in thickness and not dried sufficiently or uniformly, and after the pelleted seeds are stored for a period of time, the overall moisture content is high, and the activity of the seeds is reduced quickly; the hardness of the pelleted seeds is poor, and particularly the coating time is short; the time spent for cracking when meeting water or high humidity environment after sowing is long, thus being unfavorable for germination and emergence, and having great influence on the germination of small-particle crop seeds in particular.

5. The high multiple pelleting requirement of the small-particle seeds contradicts the subsequent quality assurance of the pelleted seeds: the weight of the small-particle seeds is required to be 20-30 times or more higher than the weight of the small-particle seeds, a binding effect is required to be achieved after a binding agent and the like are dissolved in water in the pelleting process, the shells formed in the pelleting process have high water content (the water content of the un-dried pelleting shell material is usually 30-40%), the seed storage requires that the water content of the dried pelleting seeds is required to be dried to be less than 5%, the drying temperature of the pelleting seeds cannot be higher than 50 ℃, and the uniform reduction of the water content of the pelleting shells of 20-30 times or more to be less than 5% in the temperature range is very difficult, or the long drying process influences the pelleting efficiency and greatly improves the seed pelleting cost.

Disclosure of Invention

In view of the problems in the background art, the present invention aims to provide a high-rate pelleting coating material for small-particle seeds and a coating method thereof, wherein the high-rate pelleting coating material comprises: fillers, binders, adjuvants, colorants and functional auxiliaries; the filler is a mixture obtained by mixing 100 parts by weight of 200-325-mesh vermiculite powder serving as a base material, 2-10 parts by weight of potassium carbonate, 0-15 parts by weight of bentonite and 0-20 parts by weight of diatomite by using a high-speed mixer; the adhesive is a mixture prepared by mixing and stirring 1-3 parts by weight of high-viscosity hydroxypropyl methyl cellulose aqueous solution with the concentration of 3wt%, 1-3 parts by weight of sodium polyacrylate aqueous solution with the concentration of 7wt%, 3-5 parts by weight of polyvinyl alcohol aqueous solution with the concentration of 8wt% and 10-15 parts by weight of water at the temperature of 20-40 ℃ until emulsification is carried out; the dosage of the adhesive is 20-25% of that of the filler; the auxiliary agent comprises 200 meshes of talcum powder and a film-forming agent, and the mass ratio is 1:1; the colorant is an aqueous color paste which does no harm to seeds, and the color of the colorant is the same as that of the film-forming agent; the functional auxiliary agent comprises one or a combination of a microbial fertilizer, a trace element fertilizer and a water-retaining agent.

Optionally, the trace element fertilizer comprises one or a combination of a boron fertilizer, a zinc fertilizer, a manganese fertilizer, a molybdenum fertilizer, a copper fertilizer and an iron fertilizer; the water-retaining agent is super absorbent polymer resin SAP.

The invention provides a high-rate pelleting coating method for small-particle seeds, which adopts the high-rate pelleting coating material for the small-particle seeds, and comprises the following steps: the first stage is as follows: coating the seeds in the kernel forming stage to obtain kernel pelleted seeds with the radius of 'seed radius +0.2 mm'; and a second stage: coating the core pelletized seeds in order to increase the pelleting stage to obtain the increased pelleted seeds with the radius of 'target radius-0.1 mm'; and a third stage: and in the film forming and polishing stage, the enlarged pelleted seeds are subjected to film forming and polishing to obtain high-magnification pelleted seeds with target radiuses.

Optionally, the kernel forming stage includes the following steps: firstly, averagely dividing seeds to be pelletized into K1 parts according to the unit weight of a coating machine for single pelletization, and pelletizing the seeds in the inner core according to the following steps: (1) wetting: firstly, seeds are added into a coating machine, the machine is started, and the seeds are placed in the coating machine through a rotary chassis of the coating machineThrowing and rotating to form a whirling and overturning seed flow, injecting an adhesive through a liquid supply device, and continuously operating the coating machine for 30 seconds to wet the seeds without adhesion; and (2) packaging: according to the calculated result of the pelleting scheme, continuously and uniformly adding the filler under the starting state of the coating machine, then adding the adhesive according to the proportion of 20-25wt% of the filler, and after the filler and the adhesive are added, continuously operating the coating machine for 25-45 seconds to uniformly coat the filler on the seeds to obtain kernel pelleted seeds; (3) drying: starting a dryer, gradually and uniformly pouring the kernel pelletized seeds into the dryer for drying, drying by using hot air at 40-50 ℃ for 15-25min, and continuously drying at the normal temperature of not higher than 30 ℃ for 5-10min to obtain kernel pelletized seeds with the water content of not higher than 5%; the radius of the dried kernel pelletized seed is R ₀ (ii) a (4) sieving: using a plane classifier to sequentially use the sieve pore diameters of the dried kernel pelletized seeds to be 2R respectively ₀ 0.2-0.5 mm and 2R ₀ Sieving by a sieve of- (0.2-0.5) mm to remove the kernel pelleted seeds with overlarge and undersize particle sizes, and further selecting and eliminating double-particle seed pellets and non-seed pellets to obtain standard kernel pelleted seeds with uniform particle size distribution range, wherein the average coating thickness of the standard kernel pelleted seeds is 0.2mm; when K1 is greater than 1 part, repeating the above steps (1) to (4).

Optionally, the enlarged pellet stage comprises the steps of: firstly, according to the unit weight of single pelleting by a coating machine, averagely dividing standard kernel pelleting seeds formed in the first stage into K2 ₁ Parts, each part is subjected to pellet enlargement according to the following steps: (1) wetting: starting a coating machine, adding standard inner core pelletized seeds to form a seed flow, and adding a binder which is 2-5wt% of the standard inner core pelletized seeds to wet the standard inner core pelletized seeds without adhesion; (2) increasing: according to the calculated result of the pill-forming scheme, the filling agent, the adhesive and the functional auxiliary agent are synchronously and uniformly added in the starting state of the coating machine, after the addition is finished, the coating machine continues to operate for 25-45 seconds, so that the filling agent, the adhesive and the functional auxiliary agent are uniformly mixed and gradually and uniformly coated in the standard in the repeated collision processNucleating the surface of the pelleted seed to obtain an enlarged pelleted seed; the addition amount of the adhesive is 20-25wt% of the filler, and the addition amount of the functional auxiliary agent is 0-5wt% of the filler; and (3) drying: starting a dryer, gradually and uniformly pouring the increased pelletized seeds into the dryer for drying, drying the seeds with high air flow by using hot air at the temperature of 40-50 ℃ for 20-30min, and continuously drying the seeds for 5-10min at the normal temperature of not higher than 30 ℃ to obtain the increased pelletized seeds with the water content of not higher than 5%; (4) sieving: screening the dried enlarged pelleted seeds by using a plane classifier, and removing oversize and undersize particles to obtain the enlarged pelleted seeds with equal particle size; (5) When K2 ₁ When the weight is more than 1 part, repeating the steps (1) to (4) to obtain all equal parts of the enlarged pills; (6) Carrying out nth enlargement on the enlarged and pelletized seeds according to a pelletizing scheme design, wherein N is more than or equal to 1 and less than or equal to N; dividing the volume weight of the pill into K2 equally according to the coating machine _n Repeating the increasing of one aliquot for each aliquot according to steps (1) - (4) above; through K2 _n Repeating the steps to complete the nth enlarged pill of all the seeds; after N times of enlarging the pellets, the average radius of all seeds was increased to "target radius-0.1 mm" to obtain standard enlarged pelleted seeds.

Optionally, the film forming and polishing stage comprises the following steps: firstly, dividing standard enlarged pelletized seeds obtained in the second stage into K3 parts according to the unit weight of single pelleting by a coating machine, and performing film forming and polishing according to the following steps for each part: (1) wetting: adding the standard enlarged pelleted seeds obtained in the second stage into a coating machine, starting the machine to form a seed flow, and adding a binder accounting for 2-5wt% of the standard enlarged pelleted seeds to wet the seeds in the coating machine without adhesion; (2) increase: according to the calculated result of the pelleting scheme, the filling agent, the adhesive which is equivalent to 20-25wt% of the filling agent and the coloring agent which is equivalent to 5-8wt% of the adhesive are gradually, synchronously and uniformly added under the starting state of the coating machine, so that the filling agent, the adhesive and the coloring agent are uniformly mixed in the repeated collision process and gradually and uniformly coated on the surface of the standard enlarged pelleted seed to obtain the pelleted seed to be polished; (3) polishing: adding talcum powder which is 1wt% of the seed into the pelleted seed to be polished, operating for 15s, finally adding a film-forming agent which is 1wt% of the seed, and continuously operating for 10-20s to obtain the pelleted seed after polishing; and (4) drying: drying the polished pelleted seeds with high air flow by using hot air at the temperature of 40-50 ℃ for 15-25min, and then continuously drying the pelleted seeds for 5-10min at the normal temperature of not higher than 30 ℃ to obtain standard high-rate pelleted seeds with the water content of not higher than 5%; (5) When K3 is greater than 1 part, repeating the above steps (1) to (4).

Optionally, the pelleting scheme calculation comprises the steps of:

the first step is as follows: calculating the average particle size r of the small-particle seeds

(1) Measuring the weight of each seed: taking 1000 seeds by using a seed counting instrument, combining and weighing the seeds to obtain the weight of thousand seeds, wherein the unit is g;

(2) And (3) measuring the specific gravity of the seeds: putting 1000g of seeds into a solid proportion meter, and measuring the specific gravity of the seeds with the unit of g/cm ³ ；

(3) Calculate the average single seed volume: calculating the volume of 1000 seeds in cm according to the thousand seed weight and specific gravity ³ The obtained numerical value is in mm ³ Then, is the average single seed volume v;

(4) Calculating the average single seed radius r: the shape of the small-particle seed is spherical or nearly spherical, and the average single-particle seed radius r = (3 v/4 pi) is calculated by using the average single-particle seed volume v and a spherical volume formula ^1/3 In mm;

the second step is that: calculating the maximum thickness of the pellets, the number of times N required to increase the pellets and the thickness of the pellets per increase

(1) Maximum thickness of pellet:

the maximum pelleting thickness refers to the change value of the radius of the pelleted seeds, and the maximum pelleting thickness = the target radius R-the average single seed radius R of the pelleted seeds;

(2) Increasing the theoretical number of stages of the pellet and each time increasing the thickness of the pellet:

pelleting small-particle seeds is divided into three stages: core formation, enlarging pellets and film forming polishing; wherein the thickness of the inner core of the pill in the inner core forming stage is preset to be 0.2mm, and the thickness of the film forming and polishing of the pill in the film forming and polishing stage is preset to be 0.1mm;

maximum thickness of pelletization = target radius of pelletization-radius of seed

Increasing the thickness of the pill stage = pill max thickness-core thickness-film forming finish thickness = pill max thickness-0.3 mm;

setting the thickness of each pellet increasing stage as a reference of 0.3mm, wherein the theoretical times of the increasing pellet stage = the thickness of the increasing pellet stage/0.3, and the theoretical times of the pelleting times are taken as an integer according to the principle that two digits after the obtained numerical decimal point are greater than 0.17 and less than or equal to 0.17 are rounded, namely the pelleting times N of the increasing pellet stage;

increased thickness per pellet = increased thickness/N at the pellet stage;

the third step: calculating the increased radius, single grain weight and total seed weight of the inner core pill and each increased pill stage, and obtaining the minimum preparation value of the filling agent

Determining the kernel pelleted seed radius R ₀ And the radius R after the nth enlargement of the pellet _n : wherein R is ₀ The radius of the inner core of the pill, namely the radius of the seed plus 0.2mm, R _n ＝R _n-1 + each increase in pellet thickness, wherein n refers to the nth increase of the pellet;

single seed weight gain: respectively calculating the single seed weight gain and the total seed weight gain of the kernel forming, the enlarging, the pelleting and the film forming polishing stages, and calculating the seed weight of each step of pelleting; wherein:

the single-grain weight gain is obtained according to the volume difference of single grains of the seeds before and after the formation or the increase of the inner core at this time and the specific gravity of the pellet material of 1.6, wherein:

single grain weight gain G at the core formation stage ₀ ＝(4/3*Π*R ₀ ³ －4/3*Π*r ³ ) 1.6; the unit is milligram;

single particle weight gain G after nth enlargement of pellet _n ＝(4/3*Π*R _n ³ －4/3*Π*R _n－1 ³ ) 1.6; the unit is milligram;

film forming polishing stageGrain weight = (4/3 x R) ³ －4/3*Π*(R－0.1) ³ ) 1.6, r is the target radius of standard pelleted seed; the unit is milligram;

the weight gain of all seeds was calculated as follows:

weight gain of the inner core W ₀ = Single grain weight gain of Kernel weight gain G ₀ Average weight of individual seeds total weight of seeds, i.e. the amount of filler required for the formation of the inner core of the seeds; the unit is gram;

n th pellet increased weight W _n ＝G _n The weight of single particles of the pellets to be processed at this time and the total weight of the pellets to be processed; the unit is gram;

the sum of the increased weight gains of n pelleting processes

To increase seed weight gain at the pelleting stage, i.e., the seeds increase the amount of filler required at the pelleting stage;

weight gain during the film forming and polishing stage = individual weight gain/individual pre-pelleted seed weight per total weight of pre-pelleted seed during the film forming and polishing stage; namely the quantity of the filler required in the film forming and polishing stage; the unit is gram;

the sum of the weight gain of all the seed cores, the weight gain increased by pelleting and the weight gain in the film forming and polishing stage is the total amount of the filling agent required by the whole pelleting process.

Optionally, the method further comprises the step of determining a seed pelleting scheme: dividing the total amount of the pills to be processed each time with the single maximum processing capacity of the maximum pelleting parameter of the coating machine, and rounding according to the principle of only adding but not adding to obtain the batch times, and calculating the added amount of the pills to be processed, the filling agent, the adhesive, the auxiliary agent, the coloring agent and the functional auxiliary agent according to the proportion to obtain the total pelleting scheme; wherein the maximum pelleting parameter of the coating machine is the maximum volume weight of the seeds after each pelleting of the coating machine; the pellets to be processed refer to the present seed or to the partially pelletised particles.

Optionally, the functional auxiliary agent is added in the stage of increasing the size of the pellets, and the total adding amount is the filler added in the stage of increasing the size of the pellets, namely

0-5% of (a), wherein N represents the total number of shot stages.

Optionally, an auxiliary agent and a coloring agent are added in the film-forming polishing stage, the addition proportion of the auxiliary agent talcum powder and the film-forming agent is respectively 1% of the weight of the pre-pellet seeds added in the film-forming polishing stage, and the addition amount of the coloring agent is 5-8% of the addition amount of the adhesive in the film-forming polishing stage.

The invention has the following beneficial effects:

the pill coating material and the coating method thereof solve the problems that the large-magnification pill of small-particle seeds is difficult or the pill effect is poor and the seed germination rate is influenced, and also have the functions of supplying the seeds with a microbial fertilizer, a trace element fertilizer and a high-efficiency water-retaining agent which are needed in the germination period for water retention, and the pelletized seeds can be quickly disintegrated when meeting water or in a soil humid environment to promote the germination of the seeds.

The invention relates to a large-magnification pelleting solution for small-particle seeds, which comprises three aspects of pelleting coating materials and a preparation method thereof, a formulation method of the pelleting scheme and a pelleting process flow, the technology can increase the pelleting weight of the small-particle seeds by 10-100 times or increase the particle size by 2-5 times according to the set requirement, and the pelleted seeds have uniform particles, low and consistent water content, meet the requirement of the existing sowing machinery on the particle size of the seeds, and improve the safe storage period of the pelleted seeds.

The method divides the coating process of the pellets into three stages, namely a kernel forming stage, a pellet enlarging stage and a film forming and polishing stage, accurately calculates materials used for the pelleting coating of each step, and uniformly sets the thickness of the kernel to be 0.2mm; the thickness of the shot increasing stage is not higher than 0.35 mm; the film forming and polishing stage is uniformly set to be 0.1mm, the number of non-seed particles and double-seed particles in the obtained pelleted seeds is reduced through the processes of primary nucleation, multiple weight increment and primary film forming, functional additives such as microbial fertilizers, trace element fertilizers, water-retaining agents and the like which are in direct contact with the seeds and possibly have damage to the seeds are isolated from the surfaces of the seeds, the obtained pelleted seeds are uniformly dried, and the moisture content of different positions of the pellets is consistent.

The invention also has the following beneficial effects:

1. the invention selects the adhesive which is easy to dissolve in water and the inert filler which has high hydrophilicity and is difficult to agglomerate, after sowing, the pelletized seeds are quickly split after meeting water or in a high-humidity environment of soil, and meanwhile, water retention agents (resin with extremely strong water absorption capacity) are optionally added, so that the low water content is kept during the storage of the seeds, and meanwhile, enough water can be absorbed after germination, and the germination time of the seeds can be shortened according to the difference of the pelletized seeds;

2. the microbial fertilizer and the rhizobium activity are properly added and maintained, the germination of seeds is promoted, the early emergence of seedlings is realized, and the effects of aligning and strengthening the seedlings are achieved. The invention adopts a low-temperature drying process, and active substances such as microbial fertilizer, rhizobium and the like added in the seed culture medium keep activity after being dried at low temperature, have the effect of promoting the growth of germs and seedlings, and can continuously play a role in the whole seed seedling stage.

3. The added microbial fertilizer, the micro-fertilizer and the water retention agent are positioned in the middle interlayer of the pelletized seeds and do not directly contact the seeds, so that the adverse effects of phytotoxicity and the like caused by the fact that the components directly contact the seeds are avoided;

4. the technical scheme adopts the process of multiple enlargement and multiple screening, the volume and the size of seeds treated by pelleting processing are uniform, the mechanical precise seed taking and precise seeding are favorably realized, meanwhile, no seed particles and double seed particles are removed after multiple screening, the proportion of seedling leakage or seedling weight after seeding is reduced, and the yield is favorably improved.

5. The process flow of the invention can ensure that the seeds are fully and uniformly dried and can be safely dried to the safe water content and the consistent water content, thereby ensuring the vitality of the seeds and ensuring that the shelf life of the pelleted seeds is not influenced.

Other features of the present invention and its advantages will become apparent from the following detailed description of exemplary embodiments of the invention.

Detailed Description

The present invention will be described in detail with reference to the following embodiments in order to make the aforementioned objects, features and advantages more comprehensible.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.

First, a high-rate pelletization coating material for small-sized seeds according to the first aspect of the present invention will be described.

The small-particle seed high-rate pelleting coating material according to the first aspect of the invention comprises a filler, a binder, an auxiliary agent, a coloring agent and a functional auxiliary agent.

The filler is a mixture obtained by mixing 100 parts by weight of 200-325-mesh vermiculite powder serving as a base material, 2-10 parts by weight of potassium carbonate, 0-15 parts by weight of bentonite and 0-20 parts by weight of diatomite by using a high-speed mixer.

The adhesive is prepared by mixing and stirring 1-3 parts by weight of high-viscosity hydroxypropyl methyl cellulose aqueous solution with the concentration of 3wt%, 1-3 parts by weight of sodium polyacrylate aqueous solution with the concentration of 7wt%, 3-5 parts by weight of polyvinyl alcohol aqueous solution with the concentration of 8wt% and 10-15 parts by weight of water at the temperature of 20-40 ℃ to form an emulsified mixture. The dosage of the adhesive is 20-25% of the dosage of the filler.

The auxiliary agent is an auxiliary material which is uniformly coated on the surface of the pelleted and increased pelleted seed, is filled with different colors according to requirements and enables the pelleted shell to be hard and bright, and comprises talcum powder and a film-forming agent, the adding amount of the auxiliary agent is 2 percent of that of the pre-pelleted seed, and the mass ratio of the talcum powder to the film-forming agent is 1:1. the talcum powder is 200 meshes of talcum powder; the film forming agent refers to a special film forming agent for seed coating sold in the market, such as L502, L088, L105 and the like sold in Yingkoai company, and the film forming agent should have a bright color for distinguishing different seeds after pelleting.

The functional auxiliary agent is substances for promoting growth in a seedling planting period, such as a microbial fertilizer, a trace element fertilizer, a water-retaining agent and the like, and is selected according to the type of the pellet seeds and the difference of planting environment after the seeds are pelletized. The microbial fertilizer is a biological fertilizer prepared by industrially culturing and fermenting one or more beneficial microorganisms; the trace element fertilizer refers to a fertilizer containing trace elements which are few in crop absorption amount and indispensable, and generally refers to boron fertilizer, zinc fertilizer, manganese fertilizer, molybdenum fertilizer, copper fertilizer, iron fertilizer and the like; the water-retaining agent is super absorbent polymer resin which has high water absorption capacity after meeting water, stores water and can absorb the stored water when seeds germinate.

The colorant is the ground color of the seed film forming agent, is various non-irritant, corrosive or other water-based color pastes with different colors and no harm to the seeds, is selected according to the required pelleting appearance color and is consistent with the color of the selected film forming agent, so that the pelleting seed after film forming has a brighter appearance.

Through test comparison, after the pelleting material formula is subjected to pelleting treatment, the dried specific gravity of the pelletized and agglomerated hard shell is 1.6 +/-5 percent ³ In the scope of (1), the weight increase of other materials than the filler using the pelletization method of the present technical scheme is equivalent to the loss of the non-coated seed surface during the pelletization process and the weight of the oversize pellets (double-seed pellets) and undersize pellets (seedless pellets) to be screened out. Because the high-rate pelleting of the small-particle seeds aims at increasing the particle size of the seeds, and a small amount of functional auxiliary agents are added on the basis of the increased particle size of the seeds to facilitate the storage and the germination of the seeds, and the precision requirement is not very high, the use amount of the filling agent of the pelleting material pelleting coating and the use scheme of the pelleting material calculated according to the specific gravity of 1.6 are suitable for preparing different pelleting schemes of the small-particle seeds.

Next, a high-rate pelletization coating method for small-sized seed according to the second aspect of the present invention is described, wherein the pelletization coating method of the present invention comprises three stages of 1 formation of the inner core, N enlargement of the pellets, and 1 polishing of the film formation. The stages are as follows:

the first stage is as follows: in the kernel forming stage, the seeds to be pelletized are first formed into pellet kernels in one or more batches, one of the kernels is weighed for coring, the surface of the seeds is coated with a coating material of 0.2mm to obtain the pellet kernels, and the following steps are carried out:

(1) Wetting: adding seeds into a coating machine, starting the machine, throwing the seeds in the coating machine through a rotary chassis of the coating machine and rotating to form a convoluted seed flow, injecting an adhesive which is 2-5% of the amount of the seeds through a liquid supply device to wet the seeds without adhesion, and after the adhesive is injected, continuously operating the coating machine for 30 seconds to wet the seeds and make the seeds adhere downwards;

(2) And (3) wrapping: and (3) gradually and uniformly adding the filling agent according to the calculation result of the pelleting scheme in a starting state of the coating machine, adding the adhesive in proportion to ensure that the seeds, the filling agent and the adhesive are in full contact, and gradually and uniformly wrapping the filling agent on the surfaces of the seeds in the repeated collision process. After the filling agent and the adhesive are added, the coating machine continues to operate for 25-45 seconds, so that the filling agent can be uniformly coated on the seeds, and the pelleting of the inner core is realized; the adhesive is added in a proportion of 20-25% of the filler.

(3) And (3) drying: starting the drier, pouring the internucleated seeds into the drier to dry, drying with hot air at 40-50 deg.C for 15-25min, and drying at room temperature for 5-10min, wherein the temperature of the dried kernel is not higher than 30 deg.C and the water content of the seeds is not higher than 5%.

(4) Sieving: using a flat classifier, sieve openings with diameters of 2 × R respectively are selected ₀ 0.2-0.5 mm and 2R ₀ Sieve (0.2-0.5) mm, sieving the dried pelletized core twice, removing the oversize double-seed pellets and undersize seed-free pellets, and obtaining uniform and consistent pelletized core seeds.

The first stage is finished, the uniform spherical particles with the particle diameter of the pelleting inner core being 0.4 mm larger than the seed particle diameter (diameter) are pelletized, and when the batch of the inner core required in the stage is more than 1 time, the steps (1) to (4) are repeated.

And a second stage: and (2) a pill enlarging stage, wherein the pill is enlarged into balls once or for multiple times, functional auxiliary agents are added, and the weight of the balls is increased to a preset target size, the description refers to that the pill core obtained in the first stage or the pill core is subjected to pill enlarging for n-1 times by the following steps (1) to (4), and n refers to the enlarged pill for the nth time:

firstly, the pellets to be enlarged are equally divided into one or more batches according to the scheme determined by the second aspect, and one of the batches is weighed to enlarge the pellets.

(1) Wetting: the machine is started, pellets to be enlarged are added to form a seed stream, and a binder is added in an amount corresponding to 2% to 5% by weight of the added pellets to be enlarged to wet the seeds in the coater without sticking.

(2) Increasing: calculating to gradually, synchronously and uniformly add the filler in a starting state of the coating machine according to a pelleting scheme, adding the adhesive and the functional auxiliary agent in proportion to fully contact the pellets to be increased, the filler, the adhesive and the functional auxiliary agent, gradually and uniformly coating the filler on the surface of the seeds in a repeated collision process, and after the addition is finished, continuously operating the coating machine for 25-45 seconds to uniformly coat the filler on the seeds to realize the granulation of the increased pellets; the addition amount of the adhesive is 20-25% of the addition amount of the filler, and the addition amount of the functional auxiliary agent is 0-5% of the addition amount of the filler.

(3) And (3) drying: starting the drier, pouring the pelletized seeds into the drier for drying, drying by using hot air at 40-50 ℃ for 20-30 minutes in a large air flow manner, and then continuously drying for 5-10 minutes at normal temperature, wherein the temperature of the pelletized cores after drying is not higher than 30 ℃, and the water content of the seeds is not higher than 5%.

(4) Sieving: taking out the seeds, screening by using a plane classifier, removing oversize and undersize particles, and obtaining the 'prepelleted seeds' with uniform particles to be polished and colorized.

(5) Repeating the above steps (1) to (4) N times (N is calculated by the second aspect), the pre-pelleted seed diameter is as desired and pre-pelleted seeds of uniform size are obtained.

When the enlarged batch of pellets required for this stage is more than 1 time, the above (1) to (6) are repeated.

And a third stage: polishing, brightening and coloring

(1) Wetting: averagely dividing the pre-pelleted seeds obtained in the second stage into 1 or more batches, weighing one of the pre-pelleted seeds, adding the weighed pre-pelleted seeds into a coating machine, starting the coating machine to form a seed flow, and adding an adhesive which is 2-5% of the pre-pelleted seeds to wet the seeds in the coating machine without adhesion;

(2) Increasing: according to the difference of the grain diameter of the pre-pelleted seeds, the filling agent calculated according to the technical scheme, the adhesive which is equivalent to 20-25 percent of the adding amount of the filling agent and the coloring agent which is equivalent to 5-8 percent of the adhesive are gradually, synchronously and uniformly added into the coating machine, so that the seeds, the filling agent, the adhesive and the coloring agent are fully contacted, and the filling agent is gradually and uniformly coated on the surfaces of the seeds in the repeated collision process;

(3) Polishing: after the filling agent is added, adding talcum powder which is about equal to 1 percent of the adding amount of the pre-pelleted seeds, operating for 15 seconds, finally adding film forming agent which is equal to 1 percent of the pre-pelleted seeds, and operating for 10-20 seconds;

(4) And (3) drying: and (3) after the pelleting is finished, taking out the seeds, drying the seeds by using hot air at the temperature of 40-50 ℃ for 15-25 minutes in a large air volume manner, and then continuously drying the seeds for 5-10 minutes at the normal temperature, wherein the temperature of the inner core of the dried pellets is not higher than 30 ℃ and the water content of the seeds is not higher than 5%.

When the film formation polishing lot required at this stage is more than 1 time, the above (1) to (4) are repeated.

The third stage is completed and the result is an increase to the desired pelleted seed.

In the pelleting coating method, the dosage of the filler is obtained by summing up the total number of the core pellets, the enlarging pellets and the weight required in the film-forming and polishing stage required by the preparation method of the pelleting scheme, and the actually prepared filling quantity is more than or equal to the total number.

In the pellet coating method of the present invention, the binder is prepared in an amount of 20 to 25% of the preparation amount of the filler.

In the pelleting coating method, the functional auxiliary agent is selectively added in the stage of enlarging the pellets according to the requirement of each pelleting and the difference of the seed characteristics, and the total addition amount is that of the enlarging pelletsStage by stage with addition of fillers

0-5% (where N represents the total number of shot stages increased).

In the pelleting coating method, the auxiliary agent and the coloring agent are conventional auxiliary agents and are added in the film-forming and polishing stage without being prepared separately, the addition proportion of the auxiliary agent talcum powder and the film-forming agent is respectively 1 percent of that of the pre-pelleting seeds added in the pelleting stage, and the addition amount of the coloring agent is 5 to 8 percent of that of the binding agent in the film-forming and polishing stage.

Finally, a method of formulating a pelletization protocol of the present invention is described, comprising the steps of:

the first step is as follows: calculating the average particle size of the small-particle seeds: the small-particle seed has small particle size and large size difference, and the error of measurement and calculation by using calipers is large, the average particle size of the seeds is obtained by measuring the thousand seed weight and the seed specific gravity by the technical scheme, and the measuring method comprises the following steps:

determining the weight of the individual grains of the seed to be pelleted: taking 1000 seeds to be pelleted by a particle counting instrument, combining and weighing the seeds to be pelleted to obtain the weight of thousand seeds in grams, and taking the average number of the seeds as the weight of single seeds in milligrams;

determining the volume of a single seed to be pelleted: putting 1000g of seeds into a solid proportion instrument, and measuring the specific gravity of the seeds with the unit of g/cm ³ ；

Calculating a single seed volume: calculating the total volume value of 1000 seeds to be pelleted according to the thousand seed weight and the specific gravity, wherein the unit is cm ³ The value is in mm ³ The time is the single particle volume of the seed to be pelleted;

calculating the average radius r of the single seed: the shape of the small-particle seed is spherical or close to spherical, and the average radius r value of the single-particle seed is calculated by using the volume obtained in the above formula: r = (3/4 x volume/l) ^ (1/3), unit is millimeter.

The second step is that: determining the maximum thickness of the pelletized pellets, the number of times required to enlarge the pellets, and the thickness of each enlarged pellet

According to the technical scheme of the invention, the small-particle seed pelleting divides a kernel forming stage, a pelleting increasing stage and a film forming polishing stage into three stages, wherein the thickness of the pellets in the kernel forming stage is uniformly set to be 0.2mm, the thickness of the pellets in the film forming polishing stage is uniformly set to be 0.1mm, the increasing of the pellets refers to that the thickness of the kernel and the thickness of the film forming polishing are subtracted according to the difference value between the target particle size and the average particle size of the seeds after the required pelleting, and the weight of the pellets is increased for 1-3 times according to the thickness of the pellets which is close to 0.3mm and is not more than 0.35 mm each time, so that the thickness of each time of weight increase is uniform, and the water content of the dried seeds is lower than 5 percent and is uniform.

Calculating the maximum thickness of the pelletization: the maximum thickness of pelletization means the difference between the radius of the seed to be pelletized and the target radius of the pelletized seed, and is the maximum thickness of pelletization, the maximum thickness of pelletization = predetermined radius of pelletized seed-average radius of seed;

calculating the pelleting times N: the pelletizing process includes three stages of pelletizing kernel, enlarging pellet and forming film and polishing, and the technological scheme has kernel thickness of 0.2mm and radius of kernel of pellet R ₀ ，R ₀ = seed radius +0.2; the film-forming polishing thickness is set at 0.1mm; according to empirical values, in order to ensure uniform and sufficient drying, the thickness of the pills in the increasing stage is not more than 0.35 mm, the technical scheme takes a standard safety value of 0.3mm to ensure sufficient drying after the pills are granulated. The theoretical number of times of increasing the pill = (the maximum thickness of the pill pelleting-the thickness of the inner core pill-the thickness of the polished weight gain)/0.3 = (the maximum thickness of the pill pelleting-0.2-0.1)/0.3 = the maximum thickness of the pill pelleting/0.3-1, the number of times of the pill pelleting is taken as an integer according to the principle that two positions after the obtained numerical decimal point are greater than 0.17 and less than or equal to 0.17, namely the number N of times of the pill pelleting is taken as a value, and the thickness of any weight gain is in the interval range of 0.25-0.35 mm.

The thickness of the pellet was calculated for each increase: thickness of increase per shot = (maximum thickness of shot-0.2-0.1)/N;

the third step: calculating the increased radius, the single-grain weight and the total weight of the seeds to be processed of the inner core pill and the pill stage of each weight gain, and obtaining the minimum preparation value of the filling agent:

n-th pelleting of the inner core radius R _n And increasing the radius R after the shot _n : wherein R is ₀ Is the radius of the inner core of the pill, namely 'seed radius + 0.2', R _n ＝R _n-1 + pelletising the increased thickness each time, wherein n refers to the nth increased pellet;

single seed weight gain: respectively calculating the weight (in milligrams) of each pelletized inner core, each enlarged pelleting scheme, the single grain weight (in milligrams) in the film forming and polishing stage, the weight (in kilograms) of all seeds to be pelletized, and calculating the weight (in kilograms) of the seeds pelletized in each step; wherein:

the single grain weight gain is obtained according to the difference of the single grain volume of the kernel pill or the seeds before and after the weight gain pill of the current time and the proportion of the pill material of 1.6, wherein:

single particle weight gain of core weight gain G ₀ ＝(4/3*Л*R ₀ ³ －4/3*Л*r ³ )*1.6；

Increased single grain weight G for n-th pelletization _n ＝(4/3*Л*R _n ³ －4/3*Л*R _n－1 ³ )*1.60；

Single grain weight gain during film formation polishing = 4/3 target radius ³ 4/3 original letter (target radius-0.1) ³ )*1.6

Wherein R refers to the seed radius in millimeters (in millimeters), R ₀ The radius (unit millimeter) of the pelletized inner core with unit millimeter is r +0.2, and 1.60 is the specific gravity of the coating material dried by the pelletizing tool;

the weight gain of all the seeds to be pelleted was calculated as follows:

weight gain of the inner core W ₀ = Single grain weight gain of Kernel weight gain G ₀ Weight of single seed and weight of seed to be processed, namely the quantity of filler required for forming the kernel of the seed to be processed;

n th pellet increased weight W _n ＝G _n The weight of single seed and the weight of seed to be processed;

further, the method comprises the following steps: the sum of the increased weight gains of n pelleting processes

In order to increase the weight gain of the seeds to be processed in the pelleting stage, namely, the quantity of the filling agent required by the seeds to be processed in the pelleting stage is increased;

the weight gain of the film forming and polishing stage = single-grain weight gain/single-grain seed weight of the film forming and polishing stage and the weight of the seed to be processed; the quantity of the filling agent required by film forming and polishing of the seeds to be processed is also obtained;

the sum of the weight gain of the inner core of all the seeds to be processed, the weight gain of the seeds to be processed in the pelleting process and the weight gain of the film-forming polishing stage is the total amount of the filler required in the whole pelleting process, namely the minimum value of the preparation amount of the filler in the first part of the technical scheme;

the fifth step: determining a seed pelleting scheme: according to the steps, according to the weight of the pelletized particles in each step and the single maximum processing capacity of the maximum pelletizing parameter (the maximum volume weight of the seeds after each pelleting of the coating machine) of the coating machine, dividing, rounding to obtain the batch times according to the principle of only adding in an indiscriminate way, evenly distributing the pellets to be processed (the seeds to be pelletized or the partially pelletized particles at this time) and the filling agent, adding other auxiliary agents in proportion, and determining the processing batch number required by each step and the overall pelletizing scheme of the particles to be pelletized in each batch, wherein the following table is shown:

the present invention will be described in detail with reference to the following examples.

The raw materials used in the following examples of the present invention, unless otherwise specified, were conventional commercially available products, and the coating machine selected from those having a maximum volume weight of 10 kg per pelletization.

Example 1: the seeds of the unshelled bermuda grass are required to be enlarged to the particle size (diameter) of 2mm, functional additives are added, and red coating is carried out. The seeds are provided by Beijing Baiqing Yuan animal husbandry scientific and technological development limited company, the seed quantity is 1000g, the purity is more than 98 percent, and the germination rate is more than 85 percent. .

1. Preparing the pelleting coating material

Preparing a filling agent: the pelleting filler consists of vermiculite, potassium carbonate, bentonite and diatomite in a mass ratio of 100:10:5:20; the pill particles are prepared by mixing 22.62 kg of filler, 20 kg of 200-mesh vermiculite, 2kg of potassium carbonate, 1kg of bentonite and 4kg of diatomite for 10 minutes by using a high-speed mixer according to the principle of more than or equal to the weight of the filler, and standing for later use;

preparing an adhesive: preparing 5.5 kg of adhesive according to the proportion of about 20% of the filler, wherein the adhesive is selected from 3wt% of hydroxypropyl methyl cellulose aqueous solution, 7wt% of sodium polyacrylate aqueous solution, 8wt% of polyvinyl alcohol aqueous solution and water at the temperature of 20 ℃, mixing and stirring until all components are emulsified, and standing for later use; wherein the mass ratio of each component is 1:3:5:12;

preparing an auxiliary agent: 0.2kg of each of 200 mesh talc and L502 film former (red) from Yingkoai;

preparing a coloring agent: selecting a water-soluble red color paste HG111 of a colorant;

preparing a functional additive: taking 200g of microbial fertilizer fulvic acid potassium, 50g of trace element molybdenum fertilizer sodium molybdate, 50g of boron fertilizer boric acid, 50g of anhydrous copper sulfate and 50g of water-retaining agent as polymer resin SAP, wherein the total weight is 400 g, the proportion of the total weight of the filler in the pill increasing stage is 3.12%, and fully mixing and standing the mixture for later use;

2. making a pelleting scheme (coating material specific gravity 1.6 g/cubic centimeter)

2.1 measuring or calculating the properties of the seeds to be pelletized and the materials to be pelletized

Item	Unit	Numerical value	Description of the preferred embodiment	Remarks for note
					Thousand seed weight	Keke (Chinese character of 'Keke')	0.28	Measured to obtain
Weight per unit	Milligrams of	0.28	Computing	Equal to thousand grain weight
					Specific gravity of	G/cc	1.223	Measured to obtain
Accumulation of thousand of particles	Cubic centimeter	0.23	Computing	Thousand grain weight/specific gravity
					Volume of single grain	Cubic millimeter	0.23	Computing	= thousand grain weight
Radius r	Millimeter	0.38	Computing	(unit volume 3/4/3.14) ^ (1/3)

2.2 determining the maximum thickness of the pelletized pellets, the number of times required to enlarge the pellets and the thickness of each enlarged pellet

2.3 measurement and calculation of weight gain of single seed and dosage of filler in three stages

Index (es)	Unit of	Core formation phase	Increasing the shot stage	Polishing, brightening and hyperchromic stage
					After completion the single particle radius R _n	Millimeter	0.58	0.90	1.0
Volume of single grain	Cubic millimeter	0.82	3.05	4.19
					Single grain weight gain G _n	Milligram of	0.94	3.58	1.82
Weight Wn of all seeds to be processed	Kilogram (kilogram)	3.35	12.78	6.48
					The total weight of the finished pellets	Kilogram (kilogram)	4.35	17.13	23.62

2.4 step pelletization protocol

3. The pill-granulating coating process scheme is characterized in that the pill-granulating coating process is completed in three stages:

the first stage is as follows: preparing a pelletized core comprising the steps of:

(1) Putting 1000g of shelled bermuda grass seeds subjected to trusting processing into a coating machine, starting the machine, throwing and rotating the seeds in the coating machine through a rotating chassis of the coating machine to form a whirling and rising seed flow, adding 30g of adhesive (namely, 3 percent of the added seed amount) through a liquid supply device, and operating for 30 seconds to moisten the seeds without adhesion;

(2) After the seeds were wetted, 670g of the total amount of 3350g of filler and binder calculated in the "preparation of pelletization protocol" of this example were added, and the binder and filler were added in small amounts stepwise and simultaneously until the addition of the filler was complete to form the pelletized core seeds. After the feeding is finished, the coating machine continuously operates for 25 seconds, so that the adhesive and the filler are uniformly and firmly attached to the surface of the seeds to form a pill core;

(3) Stopping the coating machine to take seeds, gradually and uniformly adding the pelletized seed kernels into a dryer for drying treatment at 45 ℃ for 15min, then continuously drying for 5min by using normal-temperature air (at room temperature of 10-25 ℃), wherein the temperature of the dried pellet kernels is not higher than 30 ℃, and the water content of the kernels is reduced to 5%.

(4) Using a flat classifier, seed-free pellets smaller than 0.9mm and double-seed pellets larger than 1.5mm were removed with sieves having mesh diameters of 0.90 mm and 1.50 mm, respectively.

The core of the pellet obtained by the above treatment was increased in weight by 3.35 times as compared with the seed to obtain a total weight of the core of the pellet of about 4.35kg and an average particle diameter (diameter) of 1.16 mm.

And a second stage: pelletizing the inner core of the pill particles for 1 time in 2 batches to form balls, adding a functional auxiliary agent, and increasing the particle size (diameter) to 1.8mm, wherein the method comprises the following steps:

(1) Accurately weighing 2.175kg of the inner cores of the pills obtained in the first stage;

(2) Adding the weighed pelleted cores into a coating machine, starting the machine to form a seed flow, and adding 67.5g of an adhesive to wet the seeds in the coating machine without adhesion;

(3) 6.39kg of filler, 1.3kg of adhesive and one half of prepared functional additive are gradually and synchronously and uniformly added into a coating machine, so that the seeds, the filler, the adhesive and the functional additive are fully contacted, and the filler is gradually and uniformly coated on the surfaces of the seeds in the repeated collision process; after the feeding is finished, the coating machine continuously operates for 25 seconds, so that the filler, the adhesive and the functional auxiliary agent are uniformly and firmly attached to the surface of the seeds;

(4) Stopping the coating machine for taking seeds, uniformly adding the pre-pelletized seeds into a drying machine for drying treatment for 25min at 45 ℃, then continuously drying for 10min by using normal-temperature air (room temperature is 20-25 ℃), wherein the temperature of the dried pellets is not higher than 30 ℃, and the water content of the cores is reduced to be below 5%;

(5) Taking out the seeds, screening by using a plane classifier, and removing empty particles (tiny particles) which are smaller than the round holes by 1.5mm and double particles (larger particles) which are larger than the round holes by 2.3mm to obtain pre-pelletized particles with uniform particles, wherein the particle size is 1.8mm;

(6) The treatments of steps (1) to (5) were repeated in 2 batches, and the second stage was completed to obtain pre-pelleted seeds of about 17.5kg of uniform size and an increase in average particle size to about 1.8mm.

And a third stage: 17.5kg of the obtained pre-pelleted seeds were subjected to film-forming polishing, brightening and color-increasing in 3 batches

(1) Accurately weighing 5.71kg of the prepelled seeds obtained in the second stage, adding the prepelled seeds into a coating machine, starting the machine to form a seed flow, and adding 135g of a binder to wet the seeds in the coating machine without adhesion;

(2) 2.16kg of filling agent, 450g of adhesive and 12.5 g of coloring agent are gradually and synchronously and uniformly added into the coating machine, so that the seeds, the filling agent, the adhesive and the coloring agent are fully contacted, and the filling agent is gradually and uniformly coated on the surfaces of the seeds in the repeated collision process;

(3) And after the filler is added, adding 58.5g of talcum powder, operating for 15 seconds, finally adding 58.5g of film forming agent, operating for 15 seconds, and ending the shelling bermuda grass seed pelleting process.

Repeating the steps (1) - (3) for 3 times, and polishing and brightening the whole pre-pelleted seeds obtained in the second stage.

(4) Taking out the seeds for drying after the pelleting is finished, drying the seeds with high air volume by using hot air at 45 ℃, wherein the drying time is 20 minutes, and then continuously drying the seeds for 7 minutes at normal temperature, wherein the temperature of the pelleted kernel after drying is not higher than 30 ℃, and the water content of the seeds is not higher than 5%;

through the pelleting treatment of the three stages, 23.6kg of pelleted bermuda grass seeds are obtained, the average particle size of the seeds is 2.0mm, the particle size of the seeds is increased by 2.6 times, the actual thousand seed weight of the pelleted seeds is 6.6 g, and the actual weight gain is about 23.6 times.

Example 2: the petunia seeds are increased to the particle size of 2mm without adding any functional auxiliary agent, and are coated in blue. The seeds are 1000g of petunia seeds provided by Beijing Baiqing source animal husbandry scientific and technological development limited company, the purity is more than 98 percent, and the germination rate is more than 85 percent.

1. Preparing the pelleting coating material

Preparing a filling agent: determining that the coating materials are vermiculite, methyl carbonate and bentonite, and mixing the materials according to a mass ratio of 100:2:15, according to the formulation method of the pelleting scheme, 65.6 kg of filling agent is needed for the target pellets, 60 kg of 200-mesh vermiculite, 1.2 kg of potassium carbonate and 9kg of bentonite are taken according to the principle of being more than or equal to the target pellets, and are mixed for 10 minutes by a high-speed mixer to obtain 70.2kg of filling agent, and the mixture is kept stand for standby;

preparing an adhesive: preparing 17.5kg of adhesive according to the proportion of about 25% of the filler, selecting 3% of hydroxypropyl methyl cellulose aqueous solution, 7% of sodium polyacrylate aqueous solution, 8% of polyvinyl alcohol aqueous solution and water with the temperature of 40 ℃, mixing and stirring until all components are emulsified, and standing for later use; wherein the mass ratio of each component is 3:3:3:15.

preparing an auxiliary agent: 0.5 kg of each of 200 mesh talc and L088 film-forming agent (blue) from Yingkoai Co;

preparing a coloring agent: selecting water-soluble blue color paste HG111 as a colorant;

preparing a functional auxiliary agent: no functional auxiliary agent is added.

2. Method for preparing pill-forming scheme (coating machine adopting and adding the scheme has maximum single volume weight of 10 kg)

Item	Unit	Numerical value	Description of the invention	Remarks for note
					Thousand seed weight	Keke (Chinese character of 'Keke')	0.10	Measured to obtain
Weight per unit	Milligrams of	0.10	Calculating out	Equal to thousand grain weight
					Specific gravity of	G/cc	1.15	Measured to obtain
Accumulation of thousand of particles	Cubic centimeter	0.09	Computing	Thousand grain weight/specific gravity
					Volume of single grain	Cubic millimeter	0.09	Computing	= thousand grain weight
Radius r	Millimeter	0.27	Calculating out	(unit volume 3/4/3.14) ^ (1/3)

2.2 determining the maximum thickness of the pellets, the number of times required to increase the pellets and the thickness of the pellets per increase

2.3 core and enlarged pellet protocol

2.4 fractional pelletization protocol

3. The pelleting coating process flow is completed in three stages:

the first stage is as follows: preparing a pelleted core comprising the steps of:

(1) Putting 1000g of entrusted petunia seeds into a coating machine, starting the machine, throwing the seeds in the coating machine through a rotary chassis of the coating machine and rotating to form a whirling and rising seed flow, then adding 50g of adhesive (namely 5 percent of the amount of the added seeds) through a liquid supply device, and operating for 30 seconds to moisten the seeds without adhesion;

(2) After the seeds were wetted, 1445g of the total amount of 5780g of filler and binder calculated as "method of preparation of pelletization protocol" in this case were added, and the binder and filler were gradually and simultaneously added in small amounts in steps until the addition of filler was completed to form pelletized core seeds. After the feeding is finished, the coating machine continuously operates for 30 seconds, so that the adhesive and the filler are uniformly and firmly attached to the surface of the seeds to form a pill core;

(3) Stopping the coating machine to take seeds, gradually and uniformly adding the pelletized seed kernels into a drying machine for drying treatment at 50 ℃ for 25min, then continuously drying for 10min by using normal-temperature air (room temperature is 10-25 ℃), wherein the temperature of the dried pellet kernels is not higher than 30 ℃, and the water content of the kernels is reduced to 5%.

(4) Using a flat classifier, seedless pellets having a diameter of less than 0.70mm and double-seeded pellets having a diameter of greater than 1.4mm were removed with screens having mesh diameters of 0.70mm and 1.4mm, respectively.

The core of the pellet is obtained through the treatment, compared with the seed, the weight of the core of the pellet is increased by 5.78 times, the total weight of the core of the pellet is about 6.78kg, and the average particle size is increased to 0.94 mm.

And a second stage: the method comprises the following steps of (1) pelletizing twice to increase the size of balls to 1.38mm for the first time, and increasing the size of balls to 1.8mm for the second time:

the first two batches increased the particle size of the 6.78kg pellet core to 1.38 mm:

(1) 3.39kg of the cores of the pellets obtained in the first stage were added to the coating machine, the machine was started up to form a seed stream, 170g of binder was added and the run was continued for 30 seconds to wet the seeds in the coating machine without sticking.

(2) 7.295kg of filler and 1.77kg of adhesive are gradually and synchronously and uniformly added into the coating machine to ensure that the seeds, the filler and the adhesive are fully contacted, and the filler is gradually and uniformly coated on the surfaces of the seeds in the repeated collision process. After the feeding, the coating machine is continuously operated for 35 seconds, so that the adhesive and the filler are uniformly and firmly attached to the surface of the seeds.

(3) Stopping the machine to take seeds, uniformly adding the first pre-pelletized seeds into a dryer to dry for 30min at 50 ℃, then continuously drying for 8 min by using normal-temperature air (room temperature is 10-25 ℃), wherein the temperature of the dried pellets is not higher than 30 ℃, and the water content of the inner core is reduced to 5%.

(4) Taking out the seeds, and screening by using a plane classifier to remove empty particles (tiny particles) with the particle size of less than 1.0mm and double particles (larger particles) with the particle size of more than 1.8mm to obtain first-time prepelleted particles with uniform particles, wherein the particle size of the first-time prepelleted particles is 1.38mm.

After 2 batches of the treatments of steps (1) - (4) and the first enlargement of the second stage, about 21.6kg of prepelled seeds of uniform size were obtained, with an average particle size increase to about 1.38mm. Then, the second stage of pellet weight gain is carried out in three batches, and the average particle size is increased to 1.8 mm:

(1) 7.02kg of the pellets obtained in the first enlargement of the second stage were added to the coating machine, the machine was started up to form a seed stream, and 195g of binder was added to wet the seeds in the coating machine without sticking.

(2) 9.03kg of filler and 2.24kg of adhesive are gradually, synchronously and uniformly added into the coating machine to ensure that the seeds, the filler and the adhesive are fully contacted, and the filler is gradually and uniformly coated on the surfaces of the seeds in the repeated collision process. After the feeding, the coating machine is continuously operated for 35 seconds, so that the adhesive and the filler are uniformly and firmly attached to the surface of the seeds.

(3) Stopping the machine to take seeds, uniformly adding the second pre-pelleted seeds into a dryer to dry for 30min at 45 ℃, then continuously drying for 5-10min by using normal-temperature air (room temperature is 10-25 ℃), wherein the temperature of the dried pellets is not higher than 30 ℃, and the water content of the inner core is reduced to 5%.

(4) Taking out the seeds, and screening by using a plane classifier to remove empty particles (tiny particles) which are smaller than the round holes by 1.5mm and double particles (larger particles) which are larger than the round holes by 2.2mm to obtain second pre-pelleting particles with uniform particles, wherein the average particle size is 1.8mm.

After 3 batches of treatments from steps (1) - (4) and the second stage of second enlargement was completed, about 49kg of uniformly sized pre-pelleted seeds was obtained and the average particle size was increased to about 1.8mm.

And a third stage: polishing brightening and coloring

(1) Accurately weighing 7kg of the pre-pelleted seeds obtained in the second stage, adding the pre-pelleted seeds into a coating machine, starting the machine to form a seed flow, and adding 200g of adhesive to wet the seeds in the coating machine without adhesion;

(2) 2.6kg of filling agent, 650g of adhesive and 39 g of coloring agent are gradually, synchronously and uniformly added into a coating machine to ensure that the seeds, the filling agent, the adhesive and the coloring agent are fully contacted, and the filling agent is gradually and uniformly coated on the surfaces of the seeds in the repeated collision process;

(3) And after the filler is added, adding 70g of talcum powder, running for 15 seconds, finally adding 70g of film forming agent, and running for 20 seconds, thus finishing the pelleting process of the petunia seeds.

Repeating the above steps (1) - (3) 7 times, and polishing and brightening all the pre-pelleted seeds obtained in the second stage.

(4) After pelleting, taking out the seeds, drying the seeds by using hot air at 50 ℃ for 25 minutes in large air volume, and then continuously drying the seeds for 10 minutes at normal temperature, wherein the temperature of the pelleted kernel after drying is not higher than 30 ℃, and the water content of the seeds is not higher than 5%;

through the pelleting treatment of the three stages, 66.6kg of the pelleted petunia seeds are obtained, the average particle size of the seeds is 2.0mm, the particle size of the seeds is increased by 3.6 times, the actual thousand seed weight of the pelleted seeds is 6.7 g, and the actual weight gain is about 66.6 times.

Example 3: the celery seeds are enlarged to the particle size of 3.2mm. The seeds are 1500g of celery seeds provided by Beijing Baiqing source animal husbandry scientific and technological development limited company, the purity is more than 98 percent, and the germination rate is more than 85 percent.

1. Preparing the coating material for pelletizing

Preparing a filling agent: the filler is selected from vermiculite, potassium carbonate and diatomite according to a mass ratio of 100:5:20; according to the method for preparing the pelleting scheme, the pelleting celery seeds need about 105 kg of the filling agent, 85kg of 200-mesh vermiculite, 4.25 kg of potassium carbonate and 19 kg of kieselguhr are taken according to the principle of being more than or equal to the formula, mixed for 15 minutes by using a high-speed mixer to obtain 108.5kg of the filling agent, and the mixture is kept stand for later use;

preparing an adhesive: preparing 23.8 kg of adhesive according to the proportion of about 22% of the filler, selecting 3% of hydroxypropyl methyl cellulose aqueous solution, 7% of sodium polyacrylate aqueous solution, 8% of polyvinyl alcohol aqueous solution and water with the temperature of 40 ℃, mixing and stirring until all components are emulsified, and standing for later use; wherein the mass ratio of each component is 3:1:4:10.

preparing an auxiliary agent: 1.0 kg of each of 200 mesh talc and L105 film former (green) from Yingkotai corporation;

preparing a coloring agent: selecting a water-soluble green color paste HG601 as a colorant;

preparing a functional additive: taking 800g of microbial fertilizer fulvic acid potassium, 200g of trace element molybdenum fertilizer sodium molybdate and 200g of water-retaining agent (polymer resin SAP) for totally 1200 g, fully mixing, and standing for later use; according to the formulation of the pelletization scheme in this example, 78.5 kg of the filler is required to be added at the enlarged pelletization stage of the present process, and the addition ratio of the functional additive is 1.53%.

2. Method for preparing pelletizing scheme

Item	Unit of	Numerical value	Description of the preferred embodiment	Remarks for note
					Thousand seed weight	Keke (Chinese character of 'Keke')	0.4	Measured to obtain
Weight per grain	Milligrams of	0.4	Computing	Equal to thousand grain weight
					Specific gravity of	G/cc	1.21	Measured to obtain
Accumulation of thousand particles	Cubic centimeter	0.33	Computing	Weight/specific gravity
					Volume of single grain	Cubic millimeter	0.33	Computing	= accumulation of thousand particles
Radius r	Millimeter	0.43	Computing	(unit volume;)3/4/3.14)^(1/3)

2.2 determination of the number of pelletization of the core pellets

2.3 inner core and enlarged pellet protocol

2.4 fractional pelletization protocol

(1) Putting 1500g of entrusted celery seeds into a coating machine, starting the machine, throwing the seeds in the coating machine through a rotary chassis of the coating machine and rotating to form a convoluted and overturned seed flow, then adding 33g of an adhesive through a liquid supply device, and operating for 30 seconds to wet the seeds without adhesion;

(2) After the seeds were wetted, 945g of the total 4.27kg of filler and binder calculated in the "preparation of pelletization protocol" of this example were added, and the binder and filler were added in small amounts stepwise and simultaneously until the addition of the filler was complete to form the pelletized core seeds. After the feeding is finished, the coating machine continuously operates for 40 seconds, so that the adhesive and the filler are uniformly and firmly attached to the surface of the seeds to form a pill core;

(3) Stopping the coating machine to take seeds, gradually and uniformly adding the pelletized seed cores into a drying machine for drying treatment at 40 ℃ for 20min, then continuously drying for 8 min by using normal-temperature air (room temperature is 10-25 ℃), wherein the temperature of the dried pellet cores is not higher than 30 ℃, and the water content of the cores is reduced to 5%.

(4) Using a flat classifier, seedless pellets less than 1.0mm in diameter and double-seeded pellets greater than 1.5mm in diameter were removed with 1.0mm and 1.5mm mesh screens, respectively.

The core of the pellet is obtained through the treatment, compared with the seed, the weight of the core of the pellet is increased by 2.86 times, the total weight of the core of the pellet is about 5.8kg, and the average grain diameter is increased to 1.26 mm.

And a second stage: pelletizing for three times to increase into balls, adding a functional assistant, increasing for three times, increasing the particle size to 1.84mm for the first time, increasing the particle size to 2.42mm for the second time, and increasing the particle size to 3.0mm for the third time, wherein the method comprises the following steps:

first increase:

(1) The cores of the pellets obtained in the first stage were enlarged in 2 batches, 2.885kg of each batch was weighed into the coater, the machine was started to form a seed stream, 64g of binder was added and the run was continued for 30 seconds to wet the seeds in the coater without sticking.

(2) 6.635kg of filler, 1.46kg of adhesive and 101.5 g of functional additive are gradually and synchronously and uniformly added into the coating machine, so that the seeds, the filler, the adhesive and the functional additive are fully contacted, and the filler is gradually and uniformly coated on the surfaces of the seeds in the repeated collision process. After the feeding, the coating machine is continuously operated for 45 seconds, so that the adhesive and the filler are uniformly and firmly attached to the surface of the seeds.

(3) Drying the pre-pelleting: stopping the machine to take seeds, uniformly adding the first pre-pelletized seeds into a dryer for drying treatment at 40 ℃ for 20min, and then continuously drying the seeds for 5min by using normal-temperature air (room temperature is 10-25 ℃), wherein the temperature of the dried pellets is not higher than 30 ℃, and the water content of the cores is reduced to 5%.

(4) The seeds were removed and sieved using a flat classifier with mesh diameters of 1.5 and 2.3mm, respectively, and empty particles (microparticles) with a particle size of less than 1.5mm and double particles (larger particles) with a particle size of greater than 2.3mm were removed to obtain first prepelleted particles with uniform particles, the average particle size being 1.84mm.

After 2 batches of the treatments of steps (1) - (4) and the first enlargement of the second stage, approximately 19.1kg of prepelled seeds of uniform size were obtained, with an average particle size increase to approximately 1.84mm. Then, a second stage of pellet weight gain is carried out, and the pellets are increased in 5 batches:

(1) 3.91kg of the pellets obtained in the first enlargement of the second stage were weighed into the coater, the machine was started to form a seed stream, and 85g of binder was added to wet the seeds in the coater without sticking.

(2) 4.99Kg of filler, 1.1Kg of adhesive and 76.3 g of functional additive are gradually and synchronously and uniformly added into the coating machine, so that the seeds, the filler, the adhesive and the functional additive are fully contacted, and the filler is gradually and uniformly coated on the surfaces of the seeds in the repeated collision process. After the feeding, the coating machine is continuously operated for 45 seconds, so that the adhesive and the filler are uniformly and firmly attached to the surface of the seeds.

(3) Drying the pre-pelleting: stopping the machine to take seeds, uniformly adding the second pre-pelleted seeds into a dryer to dry at 40 ℃ for 20min, then continuously drying for 5min by using normal-temperature air (room temperature is 10-25 ℃), wherein the temperature of the dried pellets is not higher than 30 ℃, and the water content of the inner core is reduced to 5%.

(4) The seeds were removed and sieved using a flat classifier with sieves having 2.0mm and 2.8mm mesh, respectively, to remove empty particles (tiny particles) smaller than 2.0mm and double particles (bigger particles) larger than the round holes by 2.8mm, to obtain second prepelleted particles having uniform particles, with a particle size of 2.4mm.

After 5 batches of the treatments of steps (1) - (4) and the second enlargement at the second stage, about 44.0kg of prepelled seeds of uniform size were obtained and the average particle size increased to about 2.42 mm. Then a second stage, a third pellet weight gain was carried out, increasing in 9 batches:

(1) 4.89kg of the pellets from the second enlargement of the second stage were added to the coater, the machine was started up to form a stream of seeds, and 110g of binder was added to wet the seeds in the coater without sticking.

(2) 4.48kg of filler, 986g of adhesive and 68.5 g of functional auxiliary agent are gradually and synchronously and uniformly added into the coating machine, so that the seeds, the filler and the functional auxiliary agent of the adhesive are fully contacted, and the filler is gradually and uniformly coated on the surfaces of the seeds in the repeated collision process. After the feeding, the coating machine is continuously operated for 45 seconds, so that the adhesive and the filler are uniformly and firmly attached to the surface of the seeds.

(3) Drying the pre-pelleting: stopping the machine to take seeds, uniformly adding the second pre-pelletized seeds into a dryer to dry at 40 ℃ for 20min, and then continuously drying for 10min by using normal-temperature air (at room temperature of 10-25 ℃), wherein the temperature of the dried pellets is not higher than 30 ℃, and the water content of the cores is reduced to 5%.

(4) Taking out the seeds, screening by using a plane classifier and a screen with screen holes of 2.5mm and 3.5mm respectively, and removing empty particles (tiny particles) with the size less than 2.5mm of the round holes and larger particles with the size more than 3.5mm of the round holes to obtain third pre-pelletized particles with uniform particles, wherein the particle size is 3.0mm.

After 9 batches of the treatments of steps (1) - (4) and the third enlargement of the second stage, about 84.3kg of prepelled seeds of uniform size were obtained, with the average particle size increasing to about 3.0mm.

And a third stage: polishing, brightening and brightening: the pre-pellet seeds obtained in the second stage were 84.3kg film-polished in 11 batches, 7.66kg per batch:

(1) Accurately weighing 7.66kg of the prepelleted seeds obtained in the second stage, adding the prepelleted seeds into a coating machine, starting the machine to form a seed flow, and adding 170g of adhesive to wet the seeds in the coating machine without adhesion;

(2) 1.65kg of filling agent, 365g of adhesive and 22 g of coloring agent are gradually, synchronously and uniformly added into a coating machine to ensure that the seeds, the filling agent, the adhesive and the coloring agent are fully contacted, and the filling agent is gradually and uniformly coated on the surfaces of the seeds in the repeated collision process;

(3) And after the filler is added, adding 77g of talcum powder, operating for 15 seconds, finally adding 77g of film forming agent, and operating for 10 seconds to finish the pelleting process of the batch of celery seeds.

Repeating the steps (1) to (3) for 11 times, and polishing and brightening the whole pre-pelleted seeds obtained in the second stage.

(4) After the pelleting is finished, taking out the seeds, drying the seeds by using hot air at 40 ℃ with large air volume for 15 minutes, and then continuously drying the seeds for 5 minutes at normal temperature, wherein the temperature of the pelleted kernel after drying is not higher than 30 ℃, and the water content of the seeds is not higher than 5%;

through the pelleting treatment of the three stages, 102.5kg of pelleted celery seeds are obtained, the average particle size of the seeds is 3.2mm, the particle size of the seeds is increased by 3.7 times, the actual thousand seed weight of the pelleted seeds is 27.3 g, and the actual weight gain is about 68.3 times.

Performance testing

The pelletized seeds prepared above were used for laboratory and field comparative tests, respectively. The experiments were performed with reference to GB/T25240-2010 and GB/T15671-2009, the entire contents of which are incorporated herein by reference. And selecting main indexes such as seed rate, single seed rate, cracking degree, single seed stress resistance, uniformity, germination rate and the like as indexes for detecting whether the pelleted seeds are qualified or not (the index determination method is performed according to GB/T25240-2010 and GB/T15671-2009). The results are as follows:

TABLE 1 laboratory comparative test results

From the laboratory comparison test results, the high-rate pelleted seeds prepared by the method have good seed rate, single seed rate, cracking degree, single seed pressure resistance, uniformity and germination rate, and can solve the problems that small-particle seeds are difficult to pelletize in large rate, the pelleting effect is poor and the seed germination rate is influenced.

Although some specific embodiments of the present invention have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the invention. It will be appreciated by those skilled in the art that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A high-rate pelleting coating method for small-particle seeds is characterized in that coating materials adopted by the coating method comprise: fillers, binders, adjuvants, colorants and functional auxiliaries;

the filler is a mixture obtained by mixing 100 parts by weight of 200-325-mesh vermiculite powder serving as a base material, 2-10 parts by weight of potassium carbonate, 0-15 parts by weight of bentonite and 0-20 parts by weight of diatomite by using a high-speed mixer;

the adhesive is a mixture prepared by mixing and stirring 1-3 parts by weight of high-viscosity hydroxypropyl methyl cellulose aqueous solution with the concentration of 3wt%, 1-3 parts by weight of sodium polyacrylate aqueous solution with the concentration of 7wt%, 3-5 parts by weight of polyvinyl alcohol aqueous solution with the concentration of 8wt% and 10-15 parts by weight of water at the temperature of 20-40 ℃ until emulsification is carried out; the dosage of the adhesive is 20-25% of that of the filler;

the auxiliary agent comprises 200 meshes of talcum powder and a film forming agent, and the mass ratio is 1:1;

the colorant is an aqueous color paste which does no harm to seeds, and the color of the colorant is the same as that of the film-forming agent;

the functional auxiliary agent comprises one or a combination of a microbial fertilizer, a trace element fertilizer and a water-retaining agent;

the coating method adopting the small-particle seed high-rate pelleting coating material comprises the following steps:

the first stage is as follows: coating the seeds in the kernel forming stage to obtain kernel pelleted seeds with the radius of 'seed radius +0.2 mm';

and a second stage: coating the core pelletized seeds in order to increase the pelleting stage to obtain the increased pelleted seeds with the radius of 'target radius-0.1 mm';

and a third stage: in the film forming and polishing stage, the increased pelleted seeds are subjected to film forming and polishing to obtain high-magnification pelleted seeds with target radius;

the kernel forming phase comprises the following steps:

firstly, averagely dividing seeds to be pelletized into K1 parts according to the unit weight of a coating machine for single pelletization, and pelletizing the seeds in the inner core according to the following steps:

(1) Wetting: firstly, seeds are added into a coating machine, the machine is started, the seeds are thrown up and rotated in the coating machine through a rotating chassis of the coating machine to form a convoluted and overturned seed flow, an adhesive is injected through a liquid supply device, and the coating machine is continuously operated for 30 seconds to wet the seeds without adhesion;

(2) And (3) wrapping: according to the calculated result of the pelleting scheme, continuously and uniformly adding the filler under the starting state of the coating machine, then adding the adhesive according to the proportion of 20-25wt% of the filler, and after the filler and the adhesive are added, continuously operating the coating machine for 25-45 seconds to uniformly coat the filler on the seeds to obtain kernel pelleted seeds;

(3) And (3) drying: starting a dryer, gradually and uniformly pouring the kernel pelletized seeds into the dryer for drying, drying by using hot air at 40-50 ℃ for 15-25min, and continuously drying at the normal temperature of not higher than 30 ℃ for 5-10min to obtain kernel pelletized seeds with the water content of not higher than 5%; the radius of the dried kernel pelletized seed is R ₀ ；

(4) Sieving: using a plane classifier to sequentially use the sieve pore diameters of the dried kernel pelletized seeds to be 2R respectively ₀ 0.2-0.5 mm and 2R ₀ Sieving by a sieve of- (0.2-0.5) mm to remove the kernel pelleted seeds with overlarge and undersize particle sizes, and further selecting and eliminating double-particle seed pellets and non-seed pellets to obtain standard kernel pelleted seeds with uniform particle size distribution range, wherein the average coating thickness of the standard kernel pelleted seeds is 0.2mm;

when K1 is more than 1 part, repeating the steps (1) to (4);

the enlarged pellet stage comprises the steps of:

firstly, the first stage is formed into a standard according to the unit weight of the single pelleting by the coating machineAverage division of nuclear pelleted seed into K2 ₁ Parts, each part is subjected to pellet enlargement according to the following steps:

(1) Wetting: starting a coating machine, adding standard inner core pelletized seeds to form a seed flow, and adding 2-5wt% of adhesive to wet the standard inner core pelletized seeds without adhesion;

(2) Increasing: according to the calculated result of the pelleting scheme, synchronously and uniformly adding the filler, the adhesive and the functional auxiliary agent in the starting state of the coating machine, and after the addition is finished, continuously operating the coating machine for 25-45 seconds to uniformly mix the filler, the adhesive and the functional auxiliary agent in the repeated collision process and gradually and uniformly wrap the surface of the standard kernel pelleting seed to obtain the enlarged pelleting seed; the addition amount of the adhesive is 20-25wt% of the filler, and the addition amount of the functional auxiliary agent is 0-5wt% of the filler;

(3) And (3) drying: starting a dryer, gradually and uniformly pouring the increased pelletized seeds into the dryer for drying, drying the seeds with high air flow by using hot air at the temperature of 40-50 ℃ for 20-30min, and continuously drying the seeds for 5-10min at the normal temperature of not higher than 30 ℃ to obtain the increased pelletized seeds with the water content of not higher than 5%;

(4) Sieving: screening the dried enlarged pelleted seeds by using a plane classifier, and removing oversize and undersize particles to obtain the enlarged pelleted seeds with equal particle size;

(5) When K2 is present ₁ When the weight is more than 1 part, repeating the steps (1) to (4) to obtain all equal parts of the enlarged pills;

(6) Carrying out nth enlargement on the enlarged and pelletized seeds according to a pelletizing scheme design, wherein N is more than or equal to 1 and less than or equal to N; dividing the volume weight of the pill into K2 equally according to the coating machine _n Repeating the increasing of one aliquot for each aliquot according to steps (1) - (4) above; through K2 _n Repeating the steps to complete the nth shot enlargement of all the seeds;

after N times of pellet enlargement, the average radius of all seeds is increased to the target radius of-0.1 mm, and standard enlarged pelleted seeds are obtained;

the film forming and polishing stage comprises the following steps:

firstly, dividing standard enlarged pelleting seeds obtained in the second stage into K3 parts according to the unit weight of single pelleting by a coating machine, and performing film forming and polishing according to the following steps:

(1) Wetting: adding the standard enlarged pelleted seeds obtained in the second stage into a coating machine, starting the machine to form a seed flow, and adding a binder accounting for 2-5wt% of the standard enlarged pelleted seeds to wet the seeds in the coating machine without adhesion;

(2) Increasing: according to the calculated result of the pelleting scheme, the filling agent, the adhesive which is equivalent to 20-25wt% of the filling agent and the coloring agent which is equivalent to 5-8wt% of the adhesive are gradually, synchronously and uniformly added under the starting state of the coating machine, so that the filling agent, the adhesive and the coloring agent are uniformly mixed in the repeated collision process and gradually and uniformly coated on the surface of the standard enlarged pelleted seed to obtain the pelleted seed to be polished;

(3) Polishing: adding talcum powder which is 1wt% of the seed into the pelleted seed to be polished, operating for 15s, finally adding a film-forming agent which is 1wt% of the seed, and continuously operating for 10-20s to obtain the pelleted seed after polishing;

(4) And (3) drying: drying the polished pelleted seeds with high air flow by using hot air at the temperature of 40-50 ℃ for 15-25min, and then continuously drying the pelleted seeds for 5-10min at the normal temperature of not higher than 30 ℃ to obtain standard high-rate pelleted seeds with the water content of not higher than 5%;

(5) When K3 is more than 1 part, repeating the steps (1) to (4);

the pelleting scheme calculation comprises the following steps:

the first step is as follows: measuring and calculating the average particle size r of the small-particle seeds;

(1) Measuring the weight of each seed: taking 1000 seeds by a particle counter, combining and weighing the seeds to obtain the weight of thousand particles in unit of g;

(2) Measuring the specific gravity of the seeds: putting 1000g of seeds into a solid proportion instrument, and measuring the specific gravity of the seeds with the unit of g/cm ³ ；

(3) Calculate the average single seed volume: calculating the volume of 1000 seeds according to the thousand seed weight and specific gravity obtained in the above stepcm ³ The obtained numerical unit is converted into mm ³ Then, is the average single seed volume v;

the second step is that: calculating the maximum thickness of the pelletized pellets, the number N of times required for increasing the pellets and the thickness of the pellets increased each time;

(1) Maximum thickness of pellet:

pelletization maximum thickness = pelletization target radius-seed radius;

increasing the thickness of the pelleting stage = pelleted max thickness-core thickness-film forming polished thickness = pelleted max thickness-0.3 mm;

increased thickness per pellet = increased thickness/N at the pellet stage;

the third step: calculating the radius, single grain weight gain and total seed weight gain of the inner core pellets and the pellets at each increasing stage, and obtaining the minimum preparation value of the filler;

determining the kernel pelleted seed radius R ₀ And the nth timeIncreasing the radius R after the pellet _n : wherein R is ₀ Is the radius of the inner core of the pill, namely the radius of the seed plus 0.2mm, R _n ＝R _n-1 + each increase in pellet thickness, wherein n refers to the nth increase of the pellet;

single particle weight gain = (4/3 @ R) at film forming and polishing stage ³ －4/3*Π*(R－0.1) ³ ) 1.6, r is the target radius of the standard pelleted seed; the unit is milligram;

the weight gain of all seeds was calculated as follows:

weight gain of the inner core W ₀ = Single particle weight gain of Kernel weight gain G ₀ Average weight of single seed total weight of seed, i.e. the weight of filler required for the formation of the inner core of the seed; the unit is gram;

increased weight gain W for n-th pelletization _n ＝G _n The weight of single particles of the pellets to be processed at this time and the total weight of the pellets to be processed; the unit is gram;

the sum of the increased weight gained by n pelleting operations

To increase seed weight gain at the pelleting stage, i.e., the seeds increase the weight of filler required at the pelleting stage;

weight gain during the film forming and polishing stage = individual weight gain/individual weight of pre-pelleted seed/total weight of pre-pelleted seed during the film forming and polishing stage; the weight of the filler required in the film forming and polishing stage; the unit is gram;

the sum of the weight gain of the whole seed kernel, the weight gain of the pelleting and increasing and the weight gain of the film forming and polishing stage is the total amount of the filler required by the whole pelleting process.

2. The method for high-rate pelleting and coating of small-particle seeds of claim 1, wherein the trace element fertilizer comprises one or a combination of boron fertilizer, zinc fertilizer, manganese fertilizer, molybdenum fertilizer, copper fertilizer and iron fertilizer; the water-retaining agent is super absorbent polymer resin SAP.

3. The method for high-rate pelleting coating of small-sized seeds as claimed in claim 1, further comprising the step of determining a seed pelleting scheme: dividing the total amount of the pills to be processed each time with the single maximum processing capacity of the maximum pelleting parameter of the coating machine, and rounding according to the principle of only adding but not adding to obtain the batch times, and calculating the added amount of the pills to be processed, the filling agent, the adhesive, the auxiliary agent, the coloring agent and the functional auxiliary agent according to the proportion to obtain the total pelleting scheme; wherein the maximum pelleting parameter of the coating machine is the maximum volume weight of the seeds after each pelleting of the coating machine; the pellets to be processed refer to the present seed or to the partially pelletised particles.

4. The method for high-rate pelletization coating of small-sized seed according to claim 1, wherein the functional aid is added at the stage of increasing the size of the pellet, and the total amount of the functional aid is the amount of the filler added at the stage of increasing the size of the pellet

0-5% of (a), wherein N represents the total number of shot stages.

5. The method for high-rate pelleting and coating of small-sized seeds as claimed in claim 1, wherein an auxiliary agent and a coloring agent are added in the film-forming and polishing stage, wherein the addition ratio of the auxiliary agent talc powder to the film-forming agent is 1% of the weight of the pre-pelleted seeds added in the film-forming and polishing stage, and the addition amount of the coloring agent is 5-8% of the addition amount of the binder in the film-forming and polishing stage.