JP2022190642A - Fertilizer and production method of the same - Google Patents

Abstract

To provide a fertilizer produced by blending dust coal impregnated with acid in advance to woody biomass ashes and adjusting pH of the mix, and a production method of the same.SOLUTION: The invention relates to a fertilizer and a production method of the same, the fertilizer including woody biomass ashes obtained from a biomass combustion furnace and dust coal impregnated with acid, where the weight of the dust coal before impregnated with acid is 5-50 wt.% of the weight of the woody biomass ashes.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a fertilizer using woody biomass ash as a raw material and a method for producing the same.

In recent years, global warming has become a problem, and in order to promote the introduction of renewable energy that does not emit greenhouse gases, the feed-in tariff (FIT) law was enacted. Biomass power generation using biomass fuel is increasing, and the incineration ash (hereinafter also referred to as woody biomass ash) that is emitted along with this is increasing. It is disposed of as landfill.

On the other hand, since woody biomass ash uses woody fuel, it contains a large amount of fertilizer components such as potassium and calcium derived from wood. Combustion furnaces used for woody biomass power generation include stoker furnaces, fluidized bed furnaces, and rotary kiln furnaces. Silica sand, etc. is made to flow and fuel is burned in it, so woody biomass ash contains a large amount of silica sand powder, etc. containing a large amount of silicon content generated by abrasion of silica sand, etc. Attempts have been made to use it as a supplementary fertilizer.

In particular, plants of the Gramineae family require a large amount of silicon, and are therefore being tried to be used as useful fertilizers. For example, in Patent Document 1 (Japanese Patent Laid-Open No. 2021-14394) below, biomass incineration ash is used, and a potassium source containing 1.0% by mass or more of K O and ₂₀ % by mass or _more of SiO is added with magnesium source and / or calcium source, Mg / Ca molar ratio is 0.25 ~ 1.0 and / or Ca / Si molar ratio is 1.25 ~ 1.95 mixed raw material, 1275 ~ 1400 C., and then cooled at a rate of 30.degree. C. or less per minute to produce a siliceous fertilizer. , a fertilizer with a water-soluble silicic acid content of 13% or more and a soluble potassium content of 0.5% or more as measured by the water-weakly acidic cation exchange resin method.

In addition, in the following Patent Document 2 (Japanese Patent Application Laid-Open No. 2016-166115), since the wood incineration ash exhibits strong alkalinity, an inorganic acid exhibiting strong acidity is mixed to neutralize the alkali content of the woody biomass ash. A manufacturing method and a fertilizer are described.

JP 2021-14394 A JP 2016-166115 A

The fertilizer described in Patent Document 1 is assumed to be applied mainly to paddy field soil, but the optimum pH (hydrogen ion concentration) of paddy field soil is said to be 5.5 to 6.5. Fertilizers made from woody biomass ash, which has a high alkaline content, raise the pH of the soil. However, soil is prone to acidification due to rainwater, the application of acidic fertilizers, and the generation of organic acids due to the decomposition of organic matter. It can be applied as an improvement material, and when cultivated in flooded fields like rice, it is diluted by a large amount of water in the paddy field, so the pH of the soil does not easily increase.

On the other hand, plants of the grass family that are not submerged, such as lawns, also require a lot of silicon, but if you apply a fertilizer made from raw materials with a high alkaline content, such as woody biomass ash, the pH of the soil will tend to rise, so be careful. There is a need to. Moreover, when firing at a high temperature of 1275 to 1400° C., a special firing furnace or the like is required, which raises the manufacturing cost.

In addition, the above Patent Document 2 proposes neutralization with an inorganic acid exhibiting strong acidity. In general, biomass ash contains trace amounts of heavy metals such as chromium. When neutralized with an inorganic acid that exhibits strong acidity, some of the heavy metals are removed before they react with alkali and become neutral. It will leach out. Once eluted heavy metals adhere to biomass ash again, but since the attached heavy metals are easily eluted even with rainwater, etc., applying a fertilizer using this to the soil may contaminate the soil and groundwater.

Based on the above, attempts have been made to use woody biomass ash as a fertilizer as an effective method of recycling woody biomass ash, which has been increasing in recent years. As a result, ammonia volatilizes, and heavy metals may be eluted if neutralized with an acid in advance.

Therefore, the present inventors conducted intensive studies on a method for neutralizing woody biomass ash. As a result, the addition of pulverized coal impregnated with acid alleviates the action of strong acid on woody biomass ash and prevents the elution of heavy metals. The inventors have conceived that it is possible to reduce the pH of woody biomass ash while suppressing it, and have arrived at the present invention.

Accordingly, an object of the present invention is to provide a fertilizer that uses woody biomass ash as a raw material, suppresses volatilization of ammonium nitrogen, and hardly elutes heavy metals, and a method for producing the same.

The fertilizer of the first aspect of the present invention contains woody biomass ash generated from a biomass combustion furnace and pulverized coal impregnated with acid, and the weight of the pulverized coal before acid impregnation is equal to the weight of the woody biomass ash. It is characterized by being 5 to 50% by weight.

A fertilizer according to a second aspect of the present invention is the fertilizer according to the first aspect, wherein the biomass combustion furnace is a fluidized bed combustion furnace.

A method for producing a fertilizer according to a third aspect of the present invention includes an acid impregnation step of impregnating pulverized coal with acid, and the pulverized coal impregnated with acid in the acid impregnation step and woody biomass ash generated from a biomass combustion furnace. It is characterized by comprising a mixing step of mixing, a drying step of drying the mixed ash mixed in the mixing step, and a granulation step of granulating the dried ash dried in the drying step.

A method for producing fertilizer according to a fourth aspect of the present invention is the method for producing fertilizer according to the third aspect, wherein the biomass combustion furnace is a fluidized bed combustion furnace.

The method for producing a fertilizer according to a fifth aspect of the present invention is the method for producing a fertilizer according to the third or fourth aspect, wherein the weight of the pulverized coal before acid impregnation is 5 to the weight of the woody biomass ash. 50% by weight.

According to the fertilizer of the first aspect of the present invention, since the alkaline content contained in the woody biomass ash is neutralized by the pulverized coal impregnated with acid in advance, ammonia volatilizes when applied simultaneously with the ammonia nitrogen fertilizer. Moreover, it is possible to suppress the elution of heavy metals in the woody biomass ash due to excess acid, which would contaminate the soil and groundwater. In addition, by setting the weight of pulverized coal before acid impregnation to 5 to 50% by weight with respect to the weight of woody biomass ash, a sufficient fertilization effect can be obtained and the pulverized coal can be conspicuous and the soil can be prevented from becoming dark. .

According to the fertilizer of the second aspect of the present invention, since sand containing a large amount of silicon is used as a main fluidizing medium in the fluidized bed combustion furnace, fine particles containing a large amount of silicon are produced as wood by abrasion of the sand. Since it is mixed with biomass ash, it becomes a fertilizer that contains silicon in addition to the potassium and calcium contained in woody biomass ash, so the fertilizing effect of silicon can be obtained especially for plants of the grass family that require silicon. be done.

According to the method for producing a fertilizer according to the third aspect of the present invention, the amount of acid-impregnated pulverized coal mixed can be selected for use as a soil conditioner, base fertilizer, and top dressing, and the soil and groundwater are contaminated with heavy metals. It is possible to provide a fertilizer that can suppress

According to the method for producing a fertilizer according to the fourth aspect of the present invention, in addition to wood-derived potassium and calcium, silicon is eluted from the fine sand produced from the fluid medium, so a fertilizer having a fertilizing effect of silicon can be provided.

According to the method for producing a fertilizer according to the fifth aspect of the present invention, a sufficient fertilization effect can be obtained by setting the weight of pulverized coal before impregnating with acid to 5 to 50% by weight with respect to the weight of woody biomass ash. It is possible to provide a fertilizer that is obtained and does not darken the soil.

It is a process block diagram of the manufacturing method of the fertilizer which concerns on embodiment of this invention. 4 is a graph showing the relationship between pH and the molar amount of sulfuric acid with respect to the weight of woody biomass ash. It is the graph which showed the relationship of the presence or absence of enforcement, and the length of a lawn.

A fertilizer and a method for producing the same according to embodiments of the present invention will be described below. However, the embodiments shown below are intended to exemplify fertilizers and methods for producing the same for embodying the technical idea of the present invention, and are not intended to limit the present invention to these. are equally applicable to other embodiments within the scope of

[Embodiment]
Hereinafter, a method for producing a fertilizer according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a process block diagram of a fertilizer manufacturing method according to an embodiment of the present invention.
A method for producing a fertilizer according to an embodiment of the present invention includes an acid impregnation step (a) of impregnating pulverized coal with acid, and a mixing step of mixing pulverized coal impregnated with acid and woody biomass ash generated from a biomass combustion furnace. (b), a drying step (c) for drying the mixed ash, and a granulation step (d) for granulating the dried mixed ash.

Each step will be described in detail below.
(a) Acid impregnation step In this step, pulverized coal is impregnated with an acid such as sulfuric acid. Since pulverized coal has countless fine pores, acid can be absorbed in the pores in advance. The impregnating acid is not particularly limited, and the type and concentration of the acid are adjusted according to the pH of the woody biomass ash.
The pulverized charcoal may be a commercially available fine charcoal powder, and is not particularly limited.

(b) Mixing step In this step, the woody biomass ash generated from the biomass combustion furnace and the pulverized coal impregnated with acid are mixed. When this acid-impregnated pulverized coal is mixed with the woody biomass, the acid neutralizes the alkali content such as calcium contained in the woody biomass ash. At this time, neutralization water generated by the neutralization dilutes the acid in contact with the alkaline component, raising the pH and suppressing the elution of heavy metals.

Once diluted, the acid seeps out of the pulverized coal, lowers the pH, further neutralizes the alkali content of the woody biomass ash, and reduces the overall alkali content. At this time, the acid impregnated into the pulverized coal seeps out through the fine pores of the pulverized coal, so the excess acid is not supplied to the alkali content at once, and a partial excess acid occurs. Therefore, the elution of heavy metals in woody biomass ash is suppressed.

On the other hand, if a strong acid is directly mixed with the woody biomass ash, there is a risk that a partially excessive acid will act on the woody biomass ash, eluting heavy metals and the like. Heavy metals once eluted remain attached to the surface of the woody biomass ash. Since the remaining heavy metals are likely to be eluted by rainwater or the like, they may contaminate soil and groundwater.

When woody biomass ash is neutralized by mixing it with a weak acid or a diluted strong acid, the elution of heavy metals from woody biomass ash is suppressed, but a relatively large amount of water remains. It needs to be dried, but when pulverized coal impregnated with acid is mixed, the moisture content is originally low, and the heat of neutralization evaporates the moisture, making it possible to adjust the moisture content to a level suitable for granulation. , the drying time before granulation can be shortened or omitted.

The amount of pulverized coal mixed with the woody biomass ash varies depending on the acid to be impregnated and the alkalinity of the woody biomass ash. Making it almost neutral results in a good fertilizer, but if the amount of pulverized coal is reduced, the fertilizer becomes alkaline. Therefore, it can also serve as a soil improvement material for acidic soil. Also, if the amount of pulverized coal is increased, it can be made almost neutral, so it can be used as base fertilizer and top dressing. As for the mixing method and device, a general mixing method and device such as a mixer can be used.

(c) Drying step In this step, the mixed ash mixed in the mixing step is dried to a moisture content suitable for granulation. The mixed ash obtained by mixing woody biomass ash and acid-impregnated pulverized coal can be adjusted in advance to have a moisture content suitable for granulation, in which case this step can be omitted.

(d) Granulation step In this step, mixed ash obtained by mixing woody biomass ash and pulverized coal impregnated with acid is granulated by a granulator. If the mixed ash is scattered as it is, it will scatter, and if it gets wet, it will become lumpy and difficult to apply, so it is granulated. Further, by adding a water-soluble caking agent at the time of granulation, a granule more suitable for the application can be obtained. As the granulation method and apparatus, a general granulation method and granulator such as a compacting granulator, a briquetting granulator, an extruded granulator, and a pan-type tumbling granulator may be used. can be done.

Fertilizers are further detailed below.
When the pulverized coal is impregnated with acid, the acid impregnates the pores in the pulverized coal. When this acid-impregnated pulverized coal and woody biomass ash are mixed, the alkali content in the woody biomass ash surrounding the pulverized coal and the acid impregnated in the pulverized coal undergo a neutralization reaction to generate water and salt. Alkaline components such as calcium in the woody biomass ash are eluted into this water, and the acid in the pores of the pulverized coal is also diffused to further promote the neutralization reaction. At this time, since the acid diffuses through the pores of the pulverized coal, the alkalinity is always greater than the acid, preventing the woody biomass ash from being excessively affected by the acid and suppressing the elution of heavy metals by the strong acid. can.

The acid with which the pulverized coal is impregnated does not have to be particularly limited as long as it can neutralize the alkali content. , contributes to the fertilization effect of sulfur in addition to calcium. In addition, the use of nitric acid has the same effect of nitrogen fertilization, but if nitrate nitrogen is applied too much, it accumulates excessively in plants, etc., and the effects on the human body when eating excessively accumulated vegetables, etc. Caution is warranted due to concerns. Furthermore, when phosphoric acid is used, the fertilization effect of phosphorus can be obtained, but when the soil becomes acidic, alumina and the like that inhibit the fertilization effect of phosphoric acid become active, so it is necessary to adjust the pH to the alkaline side.

The pulverized coal to be impregnated with the acid is not particularly limited. For example, sewage sludge coal obtained by carbonizing sewage sludge contains a large amount of phosphorus. Fertilization effect is obtained.

Furthermore, a material such as zeolite or diatomaceous earth which is porous and does not react with acid can be used as an acid impregnating material. It is better to use lighter pulverized coal because it becomes difficult to handle.

By mixing pulverized coal and woody biomass ash in advance and then neutralizing with acid, a fertilizer with a similar appearance can be obtained. be done.

On the other hand, the woody biomass ash generated from the fluidized bed combustion furnace contains fine particles that are pulverized by abrasion of the sand of the fluidized medium. Since these fine particles contain a large amount of silicon and are generated by friction at high temperatures, they are extremely fine and have a large surface area. is also obtained.

The woody biomass ash generated from the fluidized bed combustion furnace originally contains a large amount of fluidized medium particles that do not contain alkali or heavy metals. It is easy to use as a fertilizer and safer because it contains less harmful substances such as heavy metals.

<Experiments on pulverized coal mixing and pH [Experimental Examples 1 to 9, Comparative Example 1]>
Fertilizers were produced by changing the concentration of impregnated acid and the amount of pulverized coal impregnated with acid in the manufacturing method of the embodiment of the present invention, and the pH thereof was measured.

First, pulverized coal was impregnated with sulfuric acid of different concentrations at an arbitrary ratio, then mixed with woody biomass ash at an arbitrary ratio, granulated, samples (Experimental Examples 1 to 9) were produced, and the weight-to-volume ratio It was mixed with pure water at 10% and the pH was measured. Also, the pH of woody biomass ash (Comparative Example 1) was measured in the same manner. The results are shown in Table 1 and FIG.

The results of Table 1 and FIG. 2 revealed the following.
By mixing woody biomass ash with pulverized coal pre-impregnated with sulfuric acid, a fertilizer with an arbitrary pH was obtained. If concentrated sulfuric acid having a concentration of 90% by weight or more is used, neutralization can be achieved with a smaller amount of sulfuric acid.

In addition, if the mixed amount of pulverized coal impregnated with sulfuric acid is increased, even low-concentration sulfuric acid can be neutralized. In general, it becomes blackish, and when it dries after application, pulverized coal floats, so it is better to impregnate with high concentration sulfuric acid in order to obtain a near-neutral fertilizer.

On the other hand, when applied to highly acidic soil, impregnation with low-concentration sulfuric acid or reducing the amount of pulverized coal impregnated with sulfuric acid can provide benefits as both a soil conditioner and a fertilizer. If the amount of pulverized coal is less than 5% by weight relative to the woody biomass ash, no improvement in pH is obtained. The acid with which the pulverized coal is impregnated is not limited to sulfuric acid, and general acids such as hydrochloric acid, nitric acid and phosphoric acid can be used.

Based on the above, a fertilizer adjusted to an arbitrary pH can be obtained by mixing pulverized coal in an amount of 5 to 50% by weight with respect to woody biomass ash.

<Experiments on Elution of Heavy Metals [Experimental Example 10, Comparative Example 2]>
A fertilizer was produced by the production method of the embodiment of the present invention, and a heavy metal elution test was conducted.
First, 50 g of pulverized coal was impregnated with 75 g of 80% sulfuric acid, then mixed with 200 g of woody biomass ash and stirred to prepare a mixed ash, which was then granulated to produce a sample with a diameter of about 3 mm (Experimental Example 10). . Next, 75 g of 80% sulfuric acid was directly mixed with 200 g of woody biomass ash, kneaded, and then granulated to produce a sample (Comparative Example 2) having a diameter of about 3 mm.
Next, the prepared samples of Experimental Example 10 and Comparative Example 2 were subjected to Kankan No. 46 elution test to measure the elution amount of heavy metals.

Table 2 shows the results of component analysis of the woody biomass ash, and Table 3 shows the results of the heavy metal elution test.

The results shown in Table 3 revealed the following.
A sample prepared by mixing pulverized coal impregnated with sulfuric acid in advance with woody biomass ash (Experimental Example 10) had a hexavalent The eluted amount of chromium Cr(VI) was reduced to one tenth. Other heavy metals showed almost no difference. Of the heavy metals, hexavalent chromium is particularly soluble in acid, so the fertilizer directly mixed with sulfuric acid eluted a lot of hexavalent chromium, whereas the fertilizer of the present invention showed the effect of impregnating pulverized coal with acid. It is thought that the difference came out from the results obtained.

<Confirmation experiment of fertilizer effect on lawn [Experimental example 11, Comparative example 3]>
A fertilizer according to an embodiment of the present invention was applied to a lawn, and its effect was confirmed. Woody biomass ash generated from a woody biomass power plant in a fluidized bed combustion furnace is mixed with pulverized coal impregnated with sulfuric acid in advance, and the lawn is top-fertilized with fertilizer adjusted to pH 5.7 (Experimental example 11) and lawn without top-fertilization (Comparative Example 3) was cultivated for one month.

After that, 20 long grasses were selected and their lengths were measured.
The results are shown in Table 4 and FIG.

その結果、追肥した芝生の最長の長さが約２５％長く、平均でも約３３％長くなり、施肥効果が確認できた。

As a result, the maximum length of the fertilized lawn was increased by about 25%, and the average length was increased by about 33%, confirming the fertilization effect.

11 pulverized coal 12 acid 13 woody biomass ash 14 fertilizer (a) acid impregnation step (b) mixing step (c) drying step (d) granulation step

Claims (5)

It contains woody biomass ash generated from a biomass combustion furnace and pulverized coal impregnated with acid, and the weight of the pulverized coal before acid impregnation is 5 to 50% by weight with respect to the weight of the woody biomass ash. Fertilizer characterized. The fertilizer according to claim 1, wherein said biomass combustion furnace is a fluidized bed combustion furnace. An acid impregnation step of impregnating pulverized coal with acid, a mixing step of mixing the pulverized coal impregnated with acid in the acid impregnation step with woody biomass ash generated from a biomass combustion furnace, and mixed ash mixed in the mixing step. and a granulation step of granulating the dried ash dried in the drying step. 4. The method for producing fertilizer according to claim 3, wherein the biomass combustion furnace is a fluidized bed combustion furnace. 6. The method for producing a fertilizer according to claim 4, wherein the weight of the pulverized coal before acid impregnation is 5 to 50% by weight with respect to the weight of the woody biomass ash.

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