JP2880754B2 - Method for producing soil conditioner - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a granular soil conditioner having low strength and numerous pores.

2. Description of the Related Art In a ceramic raw material factory, fine sand, a so-called killer, which is a by-product during the purification of raw materials, is disposed of in large quantities every year. This killer is, for example, the remaining fine particles obtained by collecting silica sand products and aggregates (ballasts) used as building materials from raw ore silica sand, and is composed of fine silica sand and clay. For example, silica (SiO ₂ ) 80-90%, alumina content (Al ₂ O ₃ ) 2-5%
Contains. In addition, the killer is usually a coagulum obtained by dewatering drainage sludge by a filter press or depositing it in a drainage tank and fixing the same, and contains fine silica sand as a main component and contains a relatively large amount of water. Settled.

Problems to be Solved by the Invention By the way, since the above-mentioned Kira is difficult to mold simply because of its composition and fine particles, it is mostly discarded in an unused state and used as a raw material for ceramic products. Is desired.

The present inventor has conducted various studies on the background of the above circumstances, and as a result, can easily granulate based on stirring the agglomerated killer in dry powder, and obtain the granules obtained by the granulation method. It has been found that when unglazed, it can be used very effectively as a soil conditioner. The present invention has been made based on such findings.

Means for Solving the Problems That is, the gist of the present invention is a method for producing a granular soil improver having low strength and numerous pores, wherein (a) fine silica sand is used as a main component. A granulating step of granulating pellets having a predetermined particle size from the agglomerates based on mixing the agglomerated agglomerates containing a large amount of moisture with the dry powder; And baking the pellets obtained in the granulation process at a temperature of 400 ° C. to 1000 ° C.

Function and Effect of the Invention In this way, the Kira sticks on the basis of mixing the agglomerated Kira with the fine silica sand as a main component and containing a large amount of moisture and condensed with the dry powder. Granulation can be performed very easily without any problems, and the pellets obtained by the granulation have a variation in particle size suitable for a soil conditioner and a non-uniform lumpy uneven surface shape,
It has excellent properties such as breathability, water permeability and drainage effect that are not inferior to natural soil conditioners. In addition, since the pellets are baked at a relatively low heat of 400 ° C. to 1000 ° C. in the unfired firing step, a myriad of small pores are formed. , Effectively promote rooting and survival of plants. Moreover, since the pellets are unbaked at a low fire temperature of 400 ° C. to 1000 ° C. and have low strength, they can weather over time and return to the soil, and are not accumulated in the soil even when used continuously. There is.

EXAMPLES Hereinafter, one application example of the present invention will be described in detail.

FIG. 1 shows a pellet 10 which is an example of a soil conditioner produced according to the method of the present invention. The pellet 10 has a myriad of fine pores suitable as a soil conditioner, and has irregularities in the size and irregularity of the soil mass, such as those having a particle size of 10 mmφ or less, and 10 to 30 mmφ. Those having two different sizes, one having a particle size of about the same size, are suitably used. Since the pellet 10 has a high water absorption with a myriad of fine pores as described above, the rooting and survival rate of the plant is reduced by being mixed into the sandy soil to provide excellent water retention. The fertilizer can be raised and the fertilizer is retained, thereby preventing the fertilizer from flowing out.
In addition, since the pellets 10 themselves have an aggregated structure, they are mixed with clay soil to enhance aeration and drainage to promote plant growth and prevent root rot. In addition, since the pellets 10 have an appropriate variation in particle size and an uneven soil-like uneven surface shape, even when used alone, fine roots of a plant can be suitably grown. Moreover, since the pellets 10 have appropriately low mechanical strength by firing, they can be relatively easily broken down and returned to the soil, and are not accumulated even when used continuously. .

The pellet 10 as described above has, for example, a porosity of 43%,
It has a water absorption of about 29% and a bulk specific gravity of about 0.75.

Next, a method for producing the soil conditioner comprising the pellets 10 will be described with reference to FIG.

First, a so-called killer, which is a main raw material, is prepared. This killer has, for example, a chemical composition in which the content of silicic acid (SiO ₂ ) is 80 to 90% and the content of alumina (Al ₂ O ₃ ) is 2 to 5%. This giraffe is usually the remaining fine particles of silica sand, ballas, and clay as products recovered from raw ore silica sand.
Although it has a mineral composition such as kaolin mineral and feldspar, it may be considered that it mainly consists of fine silica sand and clay. This killer is usually in a coagulated state obtained by dewatering the drainage sludge by a filter press or by depositing it in a drainage tank, and is condensed in a state containing a relatively large amount of water.

In the granulation step, dry powder 14 consisting of one or a mixture of dry inorganic powder such as clay with relatively low moisture content and dry organic powder such as relatively dry pulp flakes, cellulose and wood flour is padded. Into the mold mixer 16 and then agglomerated lumps of the Kira that are relatively rich in moisture
After the 12 is divided into small pieces, they are charged and mixed by a paddle type mixer 16. In this granulation step, the dry powder 14 adheres around the lumps 12
When the pulverizers 12 are separated from each other by the plow-type mixing blades of the paddle-type mixer 16, the particles 12 are successively made into small particles without sticking to each other or sticking to the plow-type mixing blades of the paddle-type mixer 16. As is well known, the paddle-type mixer 16 is a mixer of a type in which a container is rotated around a central axis with respect to a plow-shaped mixing blade rotating around an eccentric axis, and particles are separated from the mixing blade. It has a scraper that changes the direction of movement of the container and serves to clean the container.

In this granulation step, the above-mentioned lump lump 12 usually has a water content of 20% or more, so that, for example, an inorganic powder having a water content of 16% or less and an organic powder having a water content of 8% or less are mixed at a required mixing ratio. The mixture is preferably used as the dry powder 14. In addition, at the time of the above granulation, although it depends on the type of the mixer 16 and the moisture of the lump lump 12, for example, the lump lump 12
The dry powder 14 is mixed with 20 to 40% by weight with respect to 80 to 80% by weight.

The raw pellets 10 granulated as described above are passed through a first sieve 18 provided with an appropriate mesh to remove dust and excessive particles, and then heated at 400 ° C. 1000 ℃
Is fired for a predetermined time at a temperature of. In the unfired firing step, appropriate mechanical strength is imparted to the pellets 10 by the sintering action, and countless fine pores are formed by the disappearance of organic substances in the pellets 10, thereby increasing water absorption and the like. . When the sintering temperature is lower than 400 ° C., it is difficult to obtain sufficient strength as pellets of the soil conditioner, while when the sintering temperature exceeds 1000 ° C., the sintering phenomenon proceeds and the mechanical strength is unnecessarily increased. The water absorption decreases. The firing furnace 20 shown in FIG. 2 is a rotary kiln having a cylindrical furnace body 22 that can be rotated around a slightly inclined axis. The pellet 10 has a fire resistance of about SK31.

The unglazed pellets 10 as described above are passed through the second sieve 24 again, and
After being separated into pieces having a diameter of about 30 mm, they are filled in the bag 26 as they are and shipped, or packed and shipped after absorbing liquid fertilizer. In addition, the fertilizer and the pH adjuster can be contained in the pellet 10 in a solid state by absorbing the fertilizer and the pH adjuster in a liquid state and drying the pellet 10 after firing, and the pellet 10 can be granulated. At this time, a fertilizer or a pH adjuster that is not separated in the baking step may be mixed with the lump lump 12 and the dry powder 14 and included in the pellets 10.

Here, in the above-mentioned granulation process, the paddle type mixer 16 was used, but other types of solid mixers such as a rotary mixer and a spiral mixer may be used. In the rotary mixer, a mixing blade having an appropriate size is fixed to an inner wall surface of the container while the container has a shape suitable for mixing,
The container itself is rotated about a horizontal axis or a slightly inclined axis to mix the solids therein. Further, in the spiral mixing device, the solids in the longitudinal container are circulated and flown by the two shafts, which are arranged in parallel in the longitudinal container and the blades are arranged in a spiral direction and are rotated in opposite directions. It is to be mixed.

In the above-described firing step, the rotary kiln type firing furnace 20 is provided, but a single furnace of a type in which the raw pellets 10 are fired in a state of being put in a sheath, a shuttle furnace may be used. .

In addition, in the above-described granulation step and unfired firing step, granulation and firing of the pellets 10 were performed in a batch format by using the mixer 16 and the firing furnace 20, but further mass production is enabled. In order to, Kira lump 12 and dry powder 14
Can be continuously granulated based on the mixing of the particles and the granulated particles are continuously sintered and fired. That is, for example, as shown in FIG.
An extruder 28 known as a so-called kneading machine is used for efficient granulation. The lump mass 12 and the dry powder 14 put into the stirring unit 30 of the extruder 28 are mixed in the stirring unit 30 and sent to the extruding unit 32, and the mouth mold fixed to the tip of the extruder 28 While being extruded through a large number of holes 36 (only two are shown in FIG. 3) of, for example, about 3 mm to 8 mm, an extrudate from the base 34 is rotated or reciprocated at a position close to the base 34. The pellets 10 are successively granulated by successive cutting with a wire (not shown) or the like, as indicated by the dashed line. As the dry powder 14, for example, wood powder 2
Used in a mixing ratio of 3030% by weight. This mixing ratio indicates a mixing ratio at which a proper adhesiveness capable of forming the pellet 10 is obtained. If the mixing ratio is less than 2%, the effect of adding the wood powder is lost, and the molding becomes difficult due to the high adhesiveness and the pores are reduced. The rate cannot be obtained sufficiently. Conversely, if it exceeds 30%, the tackiness is reduced and molding becomes difficult. The pellets 10 thus continuously granulated are successively supplied to a fluidized roaster 38 as shown in FIG. 4, for example. A funnel 42 is provided in a portion of the fluidized roaster 38 that is heated by the burner 40, and the pellets 10 are provided in the funnel 42.
When they pass through, for example, they are continuously sintered and discharged onto the belt conveyor 44. The pellets 10 thus obtained also have innumerable fine pores and relatively suitable particle size variations, and are granulated by the extruder 28 and then fired in the fluidized roaster 38. Since it is possible to provide a certain level of soil-like uneven surface shape between them, it has a soil improvement function substantially similar to that of the above-described embodiment.

When cutting the extrudate from the base 34 by the rotation of the wire, when the wire is rotated around the center of the extrusion surface of the base 34, the large number of holes 36 of the base 34 are preferably It is arranged on a portion located on the outer peripheral side of the base 34. Further, the inside of the extruded portion 32 may be configured to be evacuated. In this case, even if the mixing ratio of the wood powder is significantly increased, it is possible to maintain the degree of adhesiveness necessary for molding. .

In the extruder 28, the base 34 is provided at the axial end of the extruding section 32, but may be provided at the outer peripheral portion of the extruding section 32. In this way, the extrusion diameter can be made smaller (for example, about 1 mmφ).

Further, in the above two embodiments, when mixing the lump lump 12 and the dry powder 14, it is also possible to add a clay having a high water content, if necessary.

The above is merely an example of the present invention, and the present invention can be variously modified without departing from the spirit thereof.

[Brief description of the drawings]

FIG. 1 is a view showing an example of a pellet manufactured by the process of FIG. FIG. 2 is a view for explaining each step of one application example of the present invention. FIG. 3 is a diagram showing an example of an extruder used in a granulation step of another application example of the present invention, and is a diagram showing a part of the extruder in a cross section. FIG. 4 is a schematic view showing an example of a fluidized roasting furnace used in the unfired firing step of another application example of the present invention. 10: Pellet (soil improver)

Claims (1)

(57) [Claims] 1. A method for producing a granular soil conditioner having a low strength and numerous pores, comprising a fine silica sand as a main component and a large amount of water, a coagulum and a dry powder. A granulation step of granulating pellets of a predetermined particle size from the agglomerate based on mixing the body with the agglomerate;
A method for producing a soil conditioner, comprising: a calcination firing step of baking at a temperature of.