KR101733224B1

KR101733224B1 - High density material with improved water resistance and durability using fallen leaves of street tree and producing method thereof

Info

Publication number: KR101733224B1
Application number: KR1020160030057A
Authority: KR
Inventors: 성용주; 김동섭
Original assignee: 충남대학교산학협력단
Priority date: 2016-03-14
Filing date: 2016-03-14
Publication date: 2017-05-08

Abstract

The present invention relates to a method of mixing at least one selected from the group consisting of starch, calcium fertilizer, wood vinegar, rice husk liquor, lignosulfonate, rosin and AKD (Alkyl ketene dimer) in a mixture obtained by mixing crushed litter with wood flour and agricultural by- And a method for producing the same, a composition for controlling the pH of a soil containing the high-density agent as an active ingredient, and a method for controlling the pH of the soil by treating the soil composition with the composition. Quot;

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-density material having excellent water resistance and durability using roadside leaves,

The present invention relates to a high-density material for imparting high value-added utilization of leaves collected from trees and trees in the trees, and to a method for producing the same. More particularly, the present invention relates to a high- Density material that can be used as a hydrophobic high-density material for various applications such as mulching materials, functional cover materials, concrete fillers, and porosity-imparting materials in artificial soil by making pellet- .

Approximately 50,000 tons of dead leaves are generated annually in the city, such as about 3,000 tons in Seoul and 800 tons in Ansan city, and the processing cost of 45,000 ~ 65,000 won per ton is consumed by each local government. Accordingly, Korean Patent Laid-Open Publication No. 2014-0119423, entitled " Method for manufacturing compost using fallen leaves, and compost using leaves produced by the method ", is used to produce organic composts by composting leaves, , But the supply is overloaded due to the increase in the occurrence of deciduous leaves due to the expansion of urban landscapes. On the other hand, demand for the farms and other places of consumers is continuously increased . In the case of such a leaf-based compost, there is no great merit other than the function as the soil compost, and the composting process is disadvantageous in that the time and place are consumed and the utility is inferior.

According to Korean Patent No. 1117765, a method of producing a solid fuel using litter is a method in which a fiber material such as a pepper bar and a corn barrel is mixed with pellets in the form of a pellet, However, the use of fallen leaves as an energy fuel such as incineration has the disadvantage of low quality due to the various extracts and ashes contained in the fallen leaves.

In addition, a variety of technologies utilizing fallen leaves have been developed. For example, Korean Patent No. 1437012 entitled "Processing Method for Processing Molds on Deciduous Leaves" and Korean Patent Publication No. 2015-0021610, "Production Method of Biomass Adsorbent Using Platanus leaves , And Korean Patent Publication No. 2011-0050825 entitled "Eco-friendly panel using fallen leaves" have been continuing efforts for high value-added utilization of leaves, but since they have low disadvantages such as low amount of material and low mechanical strength, There is a disadvantage that it is difficult to replace wood powder as raw material, and it is difficult to apply it as a practical treatment method of waste because the cost required for processing is high and the utilization effect is not remarkable.

The high density material to be implemented in the present invention is classified into a pellet or a similar structure and a material to be manufactured at a high density through a high temperature process of an organic material. Particularly, the pellet is mainly used for producing a solid fuel of biomass for cogeneration Is being produced. Such a pellet-shaped material is widely used because it increases the ease of transportation and ease of storage of bulky solid materials. In the case of wood pellets and biomass pellets, which are currently being developed as energy fuels for boilers, the raw materials for producing pellets are generally based on organic raw materials such as wood flour, sawdust, and corn stover. Therefore, There is a weak disadvantage such as structural deformation and strength reduction. This disadvantage is disadvantageous in that it is difficult to apply to a non-fuel application because it is difficult to maintain the pellet structure in the case of exposure to moisture.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned needs, and an object of the present invention is to provide a high-density material for providing high-value utilization of leaves collected from roadside trees and urban areas, The present invention also provides a high-density material having excellent durability and moisture resistance by subjecting pellets formed by mixing powders and functional additives to an additional surface treatment such as heat treatment.

In order to solve the above-mentioned problems, the present invention relates to a method for producing a green algae powder, which comprises mixing starch, calcium fertilizer, wood vinegar, rice husk sap, lignosulfonate, rosin and AKD (Alkyl ketene dimer) And then heat-treating the extruded pellets to provide a high-density material excellent in moisture resistance and durability.

Also, the present invention provides a method for producing a plant, comprising the steps of: (a) drying the leaves collected in the city center while removing foreign matter from collected leaves; (b) pulverizing the dried leaves to prepare a litter powder; (c) mixing the prepared litter with wood flour or agricultural by-products; (d) mixing at least one member selected from the group consisting of starch, calcium fertilizer, wood vinegar, chrysanthemum liquor, lignosulfonate, rosin and AKD (Alkyl ketene dimer) into the mixture of step (c) Lt; / RTI > And (e) heat-treating the pellet prepared in step (d). The present invention also provides a method of manufacturing a high-density material having excellent moisture resistance and durability.

Further, the present invention provides a high-density material excellent in moisture resistance and durability produced by the above method.

In addition, the present invention relates to a method for preparing a pellet by blending at least one selected from the group consisting of a calcium agent, a wood vinegar, a rice husk liquor and a lignosulfonate into a mixture of the ground lumber powder and wood powder or agricultural by- A composition for pH control of a soil containing a high-density agent having excellent water resistance and durability as an active ingredient is provided.

The present invention also provides a method for controlling the pH of a soil by treating the composition with the soil.

Since the leaves occurring in urban centers and roadside trees should be collected and treated within a short period of time in terms of improvement of urban beautification and urban environment, the characteristics similar to the leaves of leaves in the case of roadside trees are left unchanged. Lignin and oil components are present in a large quantity and thus have unique characteristics that can be developed as a raw material for a high density material having high moisture resistance compared with organic material-based pellets such as wood powder and sawdust. The present invention utilizes the unique characteristics of such urban- Functional high density material was developed. In addition, various methods have been devised for increasing and strengthening the water resistance property. In particular, by applying the curing property additive and the hydrophobic viscous additive and the heat treatment technique, Enhanced litter-based dense materials can be produced.

1 shows a process for producing a high-density material of the present invention.
FIG. 2 and FIG. 3 show changes in properties of the pellets according to the present invention over time.

In order to accomplish the object of the present invention, the present invention provides a method for preparing a mixture of ground white liquor and wood powder or agricultural by-products, which comprises mixing starch, calcium fertilizer, wood vinegar, rice husk liquor, lignosulfonate, rosin and AKD (Alkyl ketene dimer) The present invention provides a high-density material having excellent moisture resistance and durability, which is produced by mixing at least one selected from the group consisting of the above-mentioned materials and heat-treating the extruded pellets.

In the high-density material of the present invention, the leaves may be preferably tree leaves, which are from the group consisting of sycamore, ginkgo, poplar, cherry, meta-choir, zelkova, willow, But may be, but not limited to, sycamore or ginkgo. The leaves are characterized in that they have hydrophobic surface characteristics such as a wax component and a cuticle component on the surface. In addition, the litter powder may be a powder obtained by pulverizing litter leaves and pulverizing to a size of 40 to 60 mesh passes or less, but is not limited thereto.

Also, in the high-density preparation of the present invention, the agricultural by-products are selected from the group consisting of cornstarch, yam, chaff, rice bran, rice straw, Empty Fruit Bunch, oil palm and Palm kernel Shell , But is not limited thereto.

In the high-density material of the present invention, the blending ratio of the litter powder to the wood powder or the agricultural by-product may be 20 to 80:20 to 80, preferably 40 to 60:40 to 60, , And more preferably 50:50 by weight. Mixing at the above ratios can be made with a high density material having excellent durability and moisture resistance.

In addition, in the high density material of the present invention, the starch may be vegetable starch or oxidized starch (starch glue), which is characterized by further enhancing durability and moisture resistance of the high density material by the addition of the starch. The starch may be added in an amount of 1 to 3% based on the weight of the mixture.

In addition, in the high-density material of the present invention, the calcium material may preferably be calcium oxide (CaO). In the production of the high-density material, the calcium material is added to the material to be hardened by reacting with water vaporized during the hot- The strength and moisture release resistance could be increased. The calcium agent may be added in an amount of 0.5-1.5%, more preferably 1%, based on the weight of the mixture. When the amount of the calcium agent is less than the above range, the durability and moisture resistance of the high-density agent are not significantly improved. When the amount of the calcium agent exceeds the above range, the quality of the pellet is degraded due to the decomposition of the organic matter due to the strong alkali properties of the calcium, There is a problem that soil contamination is caused when the soil is applied.

In addition, in the high-density material of the present invention, since the vinegar has an acidity as a micro-liquid generated in the combustion process of wood, when the high-density material is prepared by mixing with the mixture, the high density material has a weak acidity, Characterized in that the neutralizing action has a function of gradually appearing continuously. The vinegar solution may be added in an amount of 1 to 4%, more preferably 3%, based on the weight of the mixture. The present invention is not limited to wood vinegar, but includes all of the secondary liquids generated during the burning process of plants, and examples thereof include rice hull root extract, bamboo fruit juice, and straw liquor.

Also, in the high-density material of the present invention, the lignosulfonate serves as an adhesive for increasing the strength of the pellets, and may be added in an amount of 2 to 4%, preferably 3%, based on the weight of the mixture.

In addition, in the high-density material of the present invention, the rosin may be added in an amount of 1 to 7%, preferably 4 to 6%, more preferably 5%, to the mixture as a vegetable extract. The addition of the rosin can further improve the durability and moisture resistance of the high-density material. In particular, since the shape can be maintained even when exposed to moisture for a long time, even when the external environment is exposed or the moisture is high, The performance structure can be maintained for a certain period of time.

In the high-density material of the present invention, the AKD (Alkyl Ketene Dimer) is a functional additive that imparts hydrophobicity to the surface by covalent bonding with a hydroxyl group of an organic material having hydrophilicity, which has been applied to various paper products such as printing paper, , It is spread over the surface when the heat of 100 ° C or more is applied, and the effect of hydrophobic development is further improved, and 1 to 3%, preferably 2% of the weight of the mixture can be added.

Further, in the high-density material of the present invention, the heat treatment may preferably be performed at 160 to 240 ° C for 3 to 7 minutes, more preferably at 200 ° C for 5 minutes. By changing the surface structure of the pellets produced through the above-described heat treatment, moisture resistance and surface porosity can be imparted. In the above conditions, the heat resistance can increase the moisture resistance without lowering the strength of the pellets, The surface hydrophilic group disappears due to bonding between the surrounding hydrophilic groups immediately before the OH group, which is the hydrophilic group of the surface, is burned with water and carbon dioxide, and microvoids are generated as the volatile components on the surface dissipate. However, when the heat treatment conditions exceed the above range, there is a problem that the strength of the pellets is greatly reduced due to thermal decomposition.

The high-density agent of the present invention imparts a certain degree of porosity to the inside of the soil due to its resistance to moisture when it is applied for soil improvement such as artificial soil, sulfur waste paper and landfill. In addition, when the solution is applied in a micro liquid, it is acidic, and when it is applied in a lignosulfonate, it is weakly acidic, which brings about effects such as soil aggregation effect or salt prevention. In addition, when a calcium material such as calcium oxide or calcium carbonate is applied, it becomes alkaline and has an acidic soil neutralizing effect.

The application field of high density material with moisture resistance is applicable to surface cover such as desolation and artificial landscaping paper, and it can be used as soil covering material such as restoration paper, waste paper, mine paper, and porosity of artificial soil And so on. In particular, it can be easily transported and stored by adjusting the shape and size of the structure variously, and it is possible to put a fixed amount at the time of application, and even when it is exposed to the outside, it can maintain a certain form due to moisture resistance, After about 1 year, it is brittle and biodegradable, so it does not cause problems such as disposal or disposal after application.

The present invention also relates to

(a) drying the leaves collected in the city center while removing foreign matter from collected leaves;

(b) pulverizing the dried leaves to prepare a litter powder;

(c) mixing the prepared litter with wood flour or agricultural by-products;

(d) mixing at least one member selected from the group consisting of starch, calcium fertilizer, wood vinegar, chrysanthemum liquor, lignosulfonate, rosin and AKD (Alkyl ketene dimer) into the mixture of step (c) Lt; / RTI > And

and (e) heat-treating the pellet prepared in the step (d). The present invention also provides a method of manufacturing a high-density material excellent in moisture resistance and durability.

The method of manufacturing a high density material of the present invention more specifically includes

(b) pulverizing the dried leaves to a size of not more than 40 to 60 mesh passes to prepare litter powder;

(c) mixing the prepared litter with the wood flour and the agricultural by-products at a weight ratio of 40 to 60:40 to 60;

(e) heat-treating the pellet produced in step (d) at 160 to 240 ° C for 3 to 7 minutes,

More specifically,

(c) mixing the prepared litter with wood flour or agricultural by-products at a weight ratio of 50:50;

(e) heat-treating the pellet prepared in step (d) at 200 ° C for 5 minutes.

The present invention also provides a high density material having excellent water resistance and durability.

The present invention also relates to a process for producing a pellet by mixing at least one member selected from the group consisting of a calcium agent, a wood vinegar, a rice husk liquor and a lignosulfonate, and heat-treating the extruded pellet A composition for pH control of a soil containing a high-density agent having excellent water resistance and durability as an active ingredient is provided.

Hereinafter, the present invention will be described in detail with reference to examples. However, the following examples are illustrative of the present invention, and the present invention is not limited to the following examples.

1. Manufacture of high-density leaves

The foreign materials such as plastics and sand were removed from the fallen leaves (sycamore and ginkgo leaves) that were collected in the city center, and the foreign materials were removed by blowing the leaves with a certain size of water. Drying of fallen leaves occurs during removal of foreign matter by wind in the barrel. The leaves separated from the foreign matter were pulverized by applying a hammer mill or a multi-blade crusher, and 40 to 60 mesh net passages were obtained, and non-pass-through particles were further pulverized.

After blending with wood powder, various biomass powder, functional additive, etc., the leaf litter was extruded to produce a high density material (pellet) and cut into a certain size. The resulting high density material was then subjected to additional surface treatments such as heat treatment.

2. Durability measurement

The durability according to the raw materials was measured by applying the vibration of 300 rpm and showing the percentage of the minute fraction separated from the pellet structure. That is, as the% durability value is higher, a lot of broken parts are generated, resulting in low durability and low water resistance.

Durability (%) = (dry weight (g) / pellet dry weight (g) of separated fine powder) × 100

Example 1: Characterization of raw materials of roadside leaves

In order to analyze the possibility of application of diagonal leaves from urban areas as diverse materials, sycamore leaves and ginkgo leaves, which are widely used as landscape and landscape trees, were collected from roads and urban parks. Mg, Fe, Cd, and Cu in the collected leaves and the remaining ash after burning are shown in Table 1, and the contents of each of the collected leaves were burned at 500 ± 25 ° C. for 4 hours, , Pb) were analyzed by ICP-MS (Inductively coupled plasma mass spectrometry) and the results are shown in Tables 2 and 3, respectively.

Ash content according to collection place and species of roadside leaves Collection place dropsy Ash content (%) Road side Sycamore 4.8 Ginkgo 8.7 In the park Sycamore 4.5 Ginkgo 7.7

As a result, it was confirmed that the amount of ash was slightly different depending on the place of collection (collection place). The ash content of the road side was higher than that of the sycamore leaf, and the ash content of the ginkgo leaf was higher than that of the sycamore leaf. A large amount of ash in the organic material may cause many problems such as a decrease in the combustion calorific value and an increase in the amount of the clinker, thereby increasing the contamination of the boiler and the like. In the case of present wood pellets for combustion, the quality standard of grade 1 pellets is less than 0.7%, and the grade of ash is less than 6% even for the lowest grade grade 4 pellets. It was found that there were many difficulties to apply.

Inorganic element composition of the roadside tree leaves by the place and species of the roadside leaves Collection place dropsy P K Ca Mg Fe CD Cu Pb (ppm) Road side Sycamore 472 3,082 19,782 1,501 137 <1 2 <1 Ginkgo 839 9,496 40,157 2,272 57 <1 <1 <1 In the park Sycamore 481 2,256 18,677 1,429 106 <1 16 <1 Ginkgo 1,356 3,813 28,083 1,746 162 <1 9 <1

(Cadmium: less than 5ppm, copper: less than 30ppm, lead: 15ppm) in all the samples were analyzed according to the element composition of the inorganic materials and harmful heavy metal content ppm) or less, and it can be applied as a soil material (fertilizer) based on the results. Also, since most of the inorganic elements are composed of P, K, Ca, Mg, and Fe, which are essential elements of the soil, they can be highly useful as soil fertilizer materials.

Analysis of Inorganic Element Composition of Roadside Leaves Collection place dropsy P K Ca Mg Fe CD Cu Pb (ppm) Road side Sycamore 8,867 1,962 335,228 22,060 2,254 <1 42 <1 Ginkgo 11,496 685 494,891 27,540 793 <1 63 <1 In the park Sycamore 9,167 1,575 341,238 24,298 2,061 <1 65 <1 Ginkgo 20,851 2,864 431,919 24,581 2,754 <1 114 <1

Table 3 shows the results of analysis of the element composition of the ash components in the ash obtained by burning the leaves of the roadside trees at 500 ± 25 ° C. for 4 hours. It was confirmed that 30 ~ 50% of calcium was present as a major constituent in the remaining ash after burning the roadside leaves, and it was confirmed that other essential elements were contained in a large amount. In this analysis, harmful heavy metal contents such as cadmium and lead were found to be very low, and that of copper was somewhat high in leaves of ginkgo trees.

Example 2: Improvement of water resistance property when applied to raw materials of urban fallen leaves

In order to analyze the effect of moisture resistance on the production of densely packed pellets using urban leaves, pellets were prepared from wood pellets which were mainly used as raw pellets, The basic raw material composition and additive ratio of each pellet are shown in Table 4. Starch was added as a base additive in 1% by weight ratio and extruded into pellets to evaluate durability and water resistance.

Evaluation of durability and water resistance of wood pellets and litter-based pellets compare Basic raw materials (%) additive(%) durability
(%) Durability according to water immersion time Leaves Wood flour 10 minutes 30 minutes 1 hours Wood flour pellets 0 100 Starch 1% 5.5% 15.7% 21.5% 63.6% Deciduous wood flour pellets in the inner city 50 50 Starch 1% 3.8% 6.2% 8.9% 13.7% Deciduous pellets in the center 100 0 Starch 1% 6.7% 7.4% 8.7% 13.2%

As a result, it was shown that pellets of downtown area can be manufactured as pellets having durability similar to that of wood when applied as a raw material for pellets. After immersing each manufacturing pellet in distilled water for 10 minutes, 30 minutes and 1 hour, As a result of measurement, water resistance was significantly increased as the composition ratio of the raw material of the fallen leaves of the inner city was higher. This is considered to be a result of the appearance of hydrophobic components such as wax contained in leaves in pellets. In addition, the use of pellets with high water resistance and moisture durability can be achieved by mixing the leaves and the leaves of the city center during the basic raw material composition, thereby improving transportation and storage.

Example 3: Improvement of Strength and Water Resistance of Pellets by Addition of Starch Adhesive and Calcium Oxide

In order to analyze the characteristics of pellets according to application of starch adhesive and calcium oxide (CaO) addition, additives such as starch 1% or starch 3% and calcium oxide (CaO ) 1%.

Evaluation of durability and moisture resistance according to starch content and calcium oxide addition compare Basic raw materials (%) additive(%)
durability
(%) Durability according to water immersion time Leaves Wood flour 10 minutes 30 minutes 1 hours Deciduous pellets in the center 50 50 Starch 1% 3.8% 6.2% 8.9% 13.7% Strengthened Urban Decay Pellets 50 50 Starch 3%, CaO 1% 1.2% 3.5% 6.1% 9.6%

As a result, the durability of the pellets was increased by the adhesive force of the starch, and the pellets were formed into pellets having relatively high water resistance even in the durability according to the water exposure time. Calcium oxide (CaO) is a calcium salt material that can increase strength and moisture releasing resistance due to its ability to react with moisture evaporated during hot pressing of pellets and cure, thereby exhibiting an additional strength enhancing effect. However, calcium oxide (CaO) is a strong alkaline chemical. Excessive addition of CaO should be applied within 1% due to degradation of organic matter and contamination of soil by alkaline salt when applied to soil. However, in the case of acid soil, Effect can be obtained.

Example 4: Soil of roadside litter pellets pH Evaluation of the effect of regulating functioning

In order to investigate the soil pH control effect of pellets, pellets containing 3% of vinegar and non-added pellets, 1% added calcium oxide, pellets of lignosulfonate And 3% added pellets, respectively. The same amount of each of the prepared mulching pellets was impregnated into water for 24 hours and leached, and then the pH of the leaching solution was measured.

Assessment of soil pH change by addition of wood vinegar and CaO compare Basic raw materials (%) additive(%) Elution pH durability(%) Leaves Wood flour Deciduous pellets in the center 50 50 - 7.71 neutrality 3.8% Deciduous pellet of grassland solution 50 50 Wood vinegar 3% 6.55 acid 4.1% Lignosulphonate inner-city litter pellets 50 50 Lignosulfonate 3% 6.91 Weak acidity 3.3% Calcium oxide center-fall leaf pellets 50 50 Calcium oxide 1% 8.14 Weakly basic 3.4%

The results showed that neutral pellets of neutral pellets were acidic, pellets of acid - treated pellets were basic, and those of lignosulfonate - added pellets showed weak acidity. Therefore, wood vinegar, calcium oxide and lignosulfonate are expected to be applicable as eco-friendly materials exhibiting functions of controlling the pH of the soil according to the characteristics and conditions of the applied soil, and preventing the salts and controlling the acidity of the soil. In addition, it is considered that it can be used in manufacturing of pellets having the property of enhancing the strength and controlling the pH of the soil by performing lignosulfonate adhesive function to increase the strength of the pellets.

Example 5: rosin Evaluation of water resistance of pellets according to addition amount

Rosin, a natural hydrophobic material extracted from conifer, was powdered to prepare pellets of 0%, 1%, and 5%, respectively, compared to the base material in which the weight of leaves and wood powder was 50:50 by weight. The durability of the prepared pellets and durability according to the water immersion time were analyzed. As a result, it was considered that the effect of 1% rosin was insufficient and the strength and moisture resistance were improved when 5% was applied.

Moisture resistance of pellets according to rosin addition compare Basic raw materials (%) additive(%)
durability(%) Durability according to water immersion time Leaves Wood flour 10 minutes 30 minutes 1 hours Deciduous pellets in the center 50 50 - 7.7% 8.1% 10.5% 16.1% Rosin 1% pellets 50 50 Rosin 1% 6.1% 7.9% 11.7% 18.9% Rosin 5% pellets 50 50 Rosin 5% 3.2% 5.8% 8.7% 12.1%

Example 6: Evaluation of strength and water resistance of pellets according to surface heat treatment process

The basic pellet composed of the leaves of the inner city was prepared and heat treated at 200 ~ 300 ℃ for 5 ~ 10 minutes. The surface hydrophilicity disappears due to the bonding between the surrounding hydrophilic groups immediately before the OH group as the hydrophilic group of the pellet surface is burned by water and carbon dioxide by heat treatment at 200 DEG C or more. However, when the heat treatment temperature or time was excessive, the strength of the pellets was greatly reduced due to thermal decomposition. The inner pellet of the inner cavity was able to increase the water resistance without degrading the strength through the heat treatment at 200 ℃ for 5 minutes and it was confirmed that the strength decreased when treated for over 5 minutes at 250 ~ 300 ℃.

Strength and Water Resistance Characteristics of Pellets by Surface Heat Treatment Process compare Basic raw materials (%) Surface heat treatment conditions durability
(%) Durability according to water immersion time Leaves Wood flour Temperature (℃) Time (minutes) 10 minutes 30 minutes 1 hours Deciduous pellets in the center 50 50 0 0 5.5% 15.7% 21.5% 63.6% Surface heat treatment pellet # 1 50 50 200 5 6.8% 6.7% 7.6% 9.9% Surface Heat Treatment Pellet # 2 50 50 300 10 11.5% 10.2% 13.4% 14.1%

Claims

A mixture of powdered ground leaf, wood flour and agricultural byproducts in a weight ratio of 20 to 80: 80 to 20 is added to a mixture of starch, calcium fertilizer, wood vinegar, rice husk liquor, lignosulfonate, rosin and AKD (Alkyl ketene dimer) And then heat-treating the extruded pellets at 160 to 300 DEG C for 3 to 10 minutes to obtain a high-density pellet having excellent water resistance and durability.

2. The high-density pellet according to claim 1, wherein the litter leaves are tree litters.

The method according to claim 1, wherein the agricultural by-product is at least one selected from the group consisting of cornstalks, oilseed rape, rice hulls, rice bran, rice straw, Empty Fruit Bunch, oil palm, and Palm kernel Shell Which is excellent in moisture resistance and durability.

delete

(a) drying the leaves collected in the city center while removing foreign matter from collected leaves;
(b) pulverizing the dried leaves to prepare a litter powder;
(c) mixing the prepared litter with wood flour and wood meal or agricultural by-products at a weight ratio of 20 to 80: 80 to 20;
(d) mixing at least one member selected from the group consisting of starch, calcium fertilizer, wood vinegar, rice husk solution, lignosulfonate, rosin and AKD (Alkyl ketene dimer) into the mixture of step (c) Lt; / RTI > And
(e) heat-treating the pellet prepared in step (d) at 160 to 300 ° C for 3 to 10 minutes.

6. The method of claim 5,
(a) drying the leaves collected in the city center while removing foreign matter from collected leaves;
(b) pulverizing the dried leaves to a size of 40 to 60 mesh to prepare a litter powder;
(c) mixing the prepared leaf litter with wood powder or agricultural by-products at a weight ratio of 40 to 60: 60 to 40;
(d) mixing at least one member selected from the group consisting of starch, calcium fertilizer, wood vinegar, rice husk solution, lignosulfonate, rosin and AKD (Alkyl ketene dimer) into the mixture of step (c) Lt; / RTI > And
(e) heat-treating the pellet prepared in step (d) at 160 to 240 ° C for 3 to 7 minutes.

A high-density pellet having excellent moisture resistance and durability, produced by the method of claim 5 or 6.

Mixing at least one selected from the group consisting of calcium formate, wood vinegar, rice husk liquor and lignosulfonate into a mixture of the ground green leaf powder and wood powder or agricultural by-products at a weight ratio of 20 to 80: 80 to 20, A composition for controlling the pH of a soil containing high-density pellets having excellent water resistance and durability, prepared by heat-treating a pellet at 160 to 300 ° C for 3 to 10 minutes.

A method for controlling the pH of a soil by treating the composition of claim 8 to the soil.