JP3495301B2 - Production method of humic acid soil improvement material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a humic acid soil amendment material by effectively composting various carbon sources.

[0002]

2. Description of the Related Art In recent years, there has been a demand for a method of treating garbage (waste materials, raw garbage, etc.) and measures for reducing carbon dioxide in the atmosphere.
As these measures, a method for producing a compost containing humic acid capable of fixing carbon for a long period of time has been proposed in which various carbon sources are composted for recycling.

Humic acid is an amorphous acidic organic substance, which is usually brown or black and is also called humic acid, which is soluble in alkali and insoluble in acid existing in soil or calcareous matter with low calcification degree, It forms the organic substance inside.

Humic acid (humic acid) has an elemental composition of approximately 50-65% carbon, 4-6% hydrogen, and 1.5-nitrogen content.
6%, most of the balance is oxygen, and the chemical structure and molecular weight are still unknown, but the essence is the polycondensate of polyphenolic aromatic compounds and nitrogen-containing compounds, Microorganisms are involved in the formation.

The characteristic property of such humic acid is that the color tone thereof gradually changes to yellowish brown, reddish brown, dark brown, black brown, and black with the progress of humification. The properties change regularly in proportion to the increase of.

[0006] As a general method for separating humic acid, there are a Simon method, a sprinkel method, a Thulin method, a modified Simon method (Kobo and Taiba method), or a Kumada method. According to the Kumada method,
RF value indicating the color density per unit amount [relative chromaticity: K
₆₀₀ / 0.1N KMnO ₄ consumption amount (ml) × 1000 per 30 ml of humic acid solution used for measurement of absorbance and ΔlogK value [color coefficient: logK ₄₀₀ −log
K ₆₀₀ and K can be evaluated by the extinction coefficient at a wavelength of 400 or 600 nm.

The RF value is, for example, as shown in FIG.
Depending on the relationship between the ΔlogK value and the RF value, Rp, P, B,
The humic acid is classified into A type 4 (four regions in the graph), and the higher the RF value and the smaller the ΔlogK value, the higher the degree of humification is humic acid.

The A-type humic acid contains a large amount of carbon as described above, and is a long-term soil retention type organic material which requires a long time for decomposition by soil microorganisms. Therefore, the soil improvement effect lasts for a long period of time and helps to reduce the amount of application of other organic substances to farmland. In addition, A-type humic acid is useful for reducing the production cost of agricultural products, preventing water pollution such as groundwater by chemical fertilizer, and because the amount of carbon dioxide generated when soil microorganisms decompose various carbon sources is small, It also contributes to the suppression of carbon dioxide generation or release into the atmosphere, which is said to be the main cause of global warming.

However, it takes a long time of 200 years to produce A-type humic acid in a natural state, and it has been difficult to practically produce compost containing A-type humic acid.

As a method for producing A-type humic acid on an experimental scale in a relatively short period of time, there is known a method in which fresh volcanic ash is added to plant remains such as Japanese pampas grass and cultured at 90 ° C. for about 200 days. ing.

[0011]

However, according to the method of adding volcanic ash as described above, it is difficult to obtain fresh volcanic ash in some regions, and efficient production of A-type humic acid that can be used in addition to volcanic ash is possible. The raw material was unknown.

[0012] By the way, the inventors of the present application have conducted extensive research on A-type humic acid production raw materials that can be used in place of volcanic ash, and have collected data on the availability of coal ash under the conditions of performing prescribed pH adjustment. I found that it can be used with high practicality.

Incidentally, the coal ash used in the invention of the present application generates about 5.5 million tons per year in Japan with the operation of a thermal power plant, 80% of which is fly ash, and fly ash is 50 to 50% of that. 60% has been utilized as an additive in cement. Clinker ash, which is a type of coal ash and is granular, is used not only for civil engineering applications such as road subgrade materials, but is also directly sprayed as it is as an acid soil improver, and further application development is required. There is a situation that

Therefore, the object of the invention of the present application is to solve the above-mentioned problems and provide a new application for effective utilization of coal ash, and to generate or reduce carbon dioxide which is said to be the main cause of global warming. A new method for producing a soil improving material containing A-type humic acid, which also contributes to the suppression of the amount released into the atmosphere, is provided, and such a soil improving material containing A-type humic acid can be efficiently used in the shortest possible time. It is to provide a method that can be manufactured well.

[0015]

In order to solve the above problems, in the present invention, coal ash adjusted to a pH value of 4 to 6 is added and mixed to an organic carbon source, and water is added to this mixture. The method for producing a humic acid soil improving material comprises a thermochemical reaction under a temperature condition of 90 ° C. or higher to convert into a humic acid substance containing A-type humic acid.

The carbon source in the above-mentioned production method is preferably such that the mixing ratio of coal ash and carbon source is in the range of 1: 5 to 5: 1 (weight ratio), and the mixture has a pH value of 3-8. It is preferable to carry out a thermochemical reaction within the range.

In the method for producing a material for improving humic acid soil according to the present invention, usually, coal ash showing alkalinity is adjusted to a predetermined acidic region pH value of 4 to 6, and the coal ash is mixed with a carbon source. Therefore, in this mixture, the organic matter is efficiently converted to A-type humic acid under acidic to weakly acidic conditions.

That is, by adding coal ash adjusted to a predetermined pH value, the thermochemical reaction relating to the formation of A-type humic acid proceeds efficiently, but its mechanism of action is not fully clear. .

However, the inventors of the present application have predicted that there is catalytic activity due to Al ₂ O ₃ or free aluminum ions contained in coal ash. That is, in coal ash having a pH value of less than 4 or more than pH value 6, the catalytic activity of aluminum is inactive, and conversely, the mixture is
It is considered that the thermochemical reaction is efficiently carried out in the pH value range of 3 to 8.

In the present invention, coal ash having a predetermined pH value is added to an organic carbon source and mixed, and the mixture is heated to 90 ° C.
The reason for the above temperature condition is that under temperature conditions of less than 90 ° C., a fermentation phenomenon due to the growth and growth of microorganisms in the atmosphere is observed. It takes a long time to form type humic acid, but on the other hand, at 90 ° C or higher, microbial fermentation does not occur, and conversion to type A humic acid by thermochemical reaction proceeds rapidly under the above catalytic activity. Conceivable.

Further, in the present invention, water is added to a mixture of an organic carbon source and coal ash having a predetermined pH value,
Such water is necessary for the thermochemical reaction, and as is clear from the results of the experiments (Examples and Comparative Examples) described later,
A type humic acid cannot be generated even if the thermochemical reaction is performed without replenishing water.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Organic carbon sources used in the present invention include bark, rice husks, rice straw, bamboo shoots, branches and leaves of felled trees,
Fallen leaves, waste materials, chips, sawdust, other weeds such as Japanese pampas grass, or organic substances of biological origin such as animal matter such as cattle, horses, pigs, chickens, etc. You can also use what is available and use the compost of kitchen garbage in the city. As will be apparent from the examples described below, rice straw and Japanese pampas grass are used as the organic carbon source to obtain particularly preferable results.

The coal ash used in the present invention means the ash content of coal, that is, the thermal decomposition or oxidation product of coal,
Usually, it is the ash remaining after burning coal. Since a large amount of coal ash is produced as coal ash waste (clinker ash or fly ash) from thermal power plants, it is used to efficiently use resources and provide a soil quality improvement material of stable quality. Preferably.

By the way, according to JIS standard, fly ash has a silica content of 45% or more, a water content of 1% or less, and a loss on ignition of 8%.
Below, specific gravity 1.95 or more, specific surface area 1500 cm ² / g
As mentioned above, it goes without saying that such a standardized fly ash can be used.

Clinker ash (also referred to as clinker or cole sand) melts a low melting point portion of coal to solidify the whole when the coal is fired.
It is a lump of coal ash, and it is thought that it consists of almost the same components as fly ash. As such a clinker ash, it is preferable to use a clinker ash that has been sized to a particle size of about 5 mm or less so that the clinker ash can be uniformly mixed and work efficiently.

For reference, an example of the component (%) of coal ash is as follows.
Shown below. [Jobanjinnoyama special ash] SiO₂  42.83%, Al
₂O₃  29.32%, Fe₂O₃  2.68%, Ca
O 14.83%, MgO 1.57%, Na₂O
3.49%, K₂O 0.58%, [Yoshisumi precipitated powder ash] SiO₂  57.20%, Al₂O
₃  29.31%, Fe ₂O₃  5.29%, CaO
4.06%, MgO 0.99%, SO₃1.37, N
a₂O + K₂O 1.61%, It should be noted that coal ash is strongly alkaline and pH is
Need to be processed. Mixing acid such as sulfuric acid with coal ash
And adjust the pH value to 4-6, preferably about 5
Use coal ash. As mentioned above, pH values below 4 or
Coal ash having a pH value of over 6 is included in the coal ash.
The catalytic activity of aluminum has become inactive and thermochemical
The reaction is thought to be inefficient or extremely low
It

The temperature when the organic carbon source and the coal ash are mixed and hydrolyzed and the heat is supplied from the external heat source may be a temperature range in which the thermochemical reaction can be rapidly advanced. The preferable temperature condition for this is 90 ° C or higher, preferably 90 to 160 ° C. This is because the desired thermochemical reaction is slowed down at a temperature lower than 90 ° C, and when heated to a high temperature higher than 160 ° C, the organic carbon source is carbonized, resulting in a polycondensation phenomenon such as an aromatic compound. Does not occur, and the adverse effect of inhibiting the production of A-type humic acid is likely to occur, which is not preferable.

In order to adjust to the preferable temperature conditions as described above, it is necessary to heat from the outside, and there may be mentioned a method in which a heat transfer plate or the like to which heat is supplied by a heating medium such as heating steam is installed in the mixture. .

The carbon source in the above manufacturing method has a mixing ratio (weight ratio) of coal ash and carbon source in the range of 1: 5 to 5: 1 (that is, about 15 to 85% by weight of coal ash). It is preferable. If the amount of coal ash is less than the predetermined range, it becomes difficult to efficiently generate A-type humic acid. If the amount of coal ash exceeds the predetermined range, the amount of carbon is insufficient and A-type humic acid is efficiently produced. It is difficult to produce, and the amount of strongly acidic substances such as sulfuric acid required to adjust the coal ash to a predetermined pH value range increases, and the pH is thought to be due to the buffer effect during the reaction period. The phenomenon of increasing the value is likely to occur, and further addition of acid is required.

As a result of these, there arises a problem that the economical cost is increased, such as a longer time required for producing the A-type humic acid or an increase in the amount of acid added.

[0031]

Examples and Comparative Examples [Example 1] pH by sulfuric acid treatment
Material (mixture) in which coal ash (fly ash) adjusted to a value of 5.66 and plant carbon source (crushed Japanese pampas grass) were mixed at a weight ratio of 4: 1 was used as an incubator (culture) using electric energy from the outside. The mixture was heated to 90 ° C. in a container and kept warm, an appropriate amount of water was added, and the culture was continued for 125 days. The amount of water added was 24 hours, just enough to evaporate almost all in the atmosphere, that is, about the same weight of water as the mixture was added at the same time every day.

For the morphological analysis of the humic acid produced,
According to the following Kumada method (Kumata, Ota, 1963), the RF value (relative chromaticity) and Δl indicating the color strength per unit amount of humic acid
The ogK value (an approximate value of the slope of the absorption spectrum of humic acid with respect to the wavelength axis) was examined on days 0, 70, and 125, and the results are shown in Table 1 and the chart of FIG.

<Morphological analysis method by Kumada method> (a) Extraction operation About 0.4 g of the heated culture sample was placed in a 250 ml centrifuge tube, and 50 ml of 0.1N sodium hydroxide solution (or sodium pyrophosphate solution) was added. . It was heated to 100 ° C. for 30 minutes in a steamer, shaking the centrifuge tube every 10 minutes. Then, it was cooled in water, 1 g of sodium sulfate was added to the centrifuge tube as a coagulant, and the mixture was centrifuged at 10,000 rpm for 15 minutes. The supernatant was placed in a 200 ml volumetric flask, 15 ml of 0.1N sodium hydroxide solution (or sodium pyrophosphate solution) was added to the centrifuge tube containing the residue, and the mixture was again centrifuged at 10,000 rpm for 15 minutes. Two
The supernatants obtained by centrifugation once are collected, 0.1N sodium hydroxide solution (or sodium pyrophosphate solution) is added, and the volume is adjusted to 200 ml. Then, 2 ml of concentrated sulfuric acid was gradually added to cause acid precipitation, and allowed to stand for 1 hour or more.
After the precipitation, it was filtered with a filter paper. The residue on the filter paper was washed with water: sulfuric acid (100: 1) 2-3 times, and the filtrate was washed with water: sulfuric acid (10: 1).
The volume was adjusted to 200 ml (0: 1) (fulvic acid fraction). Dissolve the residue on the filter paper with 0.1N sodium hydroxide solution (or sodium pyrophosphate solution) and add 0.1N solution.
The volume was adjusted to 100 ml with a sodium hydroxide solution (or sodium pyrophosphate solution) (humic acid fraction), and the absorption spectrum was immediately measured.

Incidentally, the humic acid adhering to Ca in the sample is not extracted in the NaOH extraction, and the humic acid adhering to Ca in the sample can be extracted in the sodium pyrophosphate extraction.

(B) Measurement of absorption spectrum Spectrophotometer Ubest-35 (JAPAN SPECTROSCOPIC C
O.LTD) first, the absorbance at 600 nm (hereinafter,
It is abbreviated as K600. ) Was measured in undiluted solution. Then 40
The value of 0 nm (hereinafter abbreviated as K400) is 0.1.
Dilute appropriately so that it falls between 2.0, K600 and K4
00 was measured. Further, dilute appropriately so that the absorbance falls between 0.1 and 2.0, and analyze the spectrum between 230 and 700.
It was measured in nm.

(C) Oxidation-reduction titration 30 ml of a sample solution of the fulvic acid fraction and the humic acid fraction was added to 200 m.
Transfer to an Erlenmeyer flask of 1 volume, 20 ml of 0.1N potassium permanganate solution, 10 ml of water: sulfuric acid (10: 1),
20 ml of water was added. Heated at 100 ° C. for 15 minutes in a steamer, shaking the flask about every 5 minutes. Immediately after taking it out, 25 ml of 0.1N oxalic acid was added to
Titration with N potassium permanganate was carried out, and the end point was the point at which the liquid remained a slight pink color for 1 minute or longer. The blanking was performed in the same manner as the others except that pure water was used instead of the sample.

(D) Calculation method ΔlogK (color tone coefficient) = logK400-logK600 RF (relative chromaticity) = K600 of undiluted solution × 1000 / {(Th-T
b) × 30 × f / Vh} [Symbol in the formula: f = 0.1N factor of potassium permanganate Tb (ml) = blank titration value Th (ml) = humic acid fraction sample titration value Vh ( ml) = amount of humic acid fraction sample used for titration

[0038]

[Table 1]

Example 2 The pH value was adjusted to 5.66 by the sulfuric acid treatment, and the coal ash (fly ash) and the plant carbon source (the crushed product of Japanese pampas grass) that had been desulfated with calcium as described below were 4: 4. Materials mixed in a weight ratio of 1 (mixture)
Heat culturing was performed in exactly the same manner as in Example 1 except that the above was used, and morphological analysis of humic acid was performed in exactly the same manner as in Example 1, and the results are also shown in Table 1 and FIG.

The above-mentioned calcium sulfate removal treatment is a treatment for adding dilute sulfuric acid to coal ash to remove the precipitated gypsum. That is, when dilute sulfuric acid is added to coal ash, calcium contained in the coal ash (not Ca contained in the particles of the coal ash but existing as a free-form calcium salt) causes the sulfate group of SO ₄ (SO ₄ ^-2 ) reacts with plaster (CaS
O ₄ ) is produced, but the gypsum becomes a white precipitate and accumulates in the lower part of the container and solidifies. Therefore, removal of this gives a coal ash sample with pH adjusted and calcium removed.

By the way, the test in which Ca was removed was carried out when the thermochemical reaction of the mixed sample was allowed to proceed in the presence of Al (presumed to be a catalyst) in the heating culture test of coal ash and carbon source. This is because there is a concern that the reaction inhibition may occur if Ca is present in the.

[Comparative Example 1] A material (mixture) in which a coal ash (fly ash) having a pH value of 9.31 and a plant carbon source (crushed grass powder) were mixed at a weight ratio of 4: 1 without pH adjustment. Heat culturing was performed in exactly the same manner as in Example 1 except that the above was used, and the morphological analysis of humic acid was performed in exactly the same manner as in Example 1, and the results are also shown in Table 1 and FIG.

As is clear from the results shown in Table 1 and FIGS. 1 to 3, in Comparative Example 1 using alkaline coal ash without pH adjustment, the RF value was less than 80 even after 125 days, No type A humic acid was produced.

On the other hand, in Comparative Example 1 in which the pH value was adjusted and the coal ash having a pH value in a predetermined acidic range was used, the RF value exceeded 80 at 125 days and A-type humic acid was produced. I understand.

[Examples 3 and 4, Comparative Examples 2 to 7] As shown in Table 2, the pH value was adjusted to 5.0 by sulfuric acid treatment, or the coal ash (frying fly) was adjusted without adjusting the pH value at all. Ash) and vegetable carbon source (rice straw) 0: 1, 1: 2, 1:
The material (mixture) mixed in a weight ratio of 1 or 5: 1 is heated and kept warm at 90 ° C or 75 ° C in an incubator (incubator), and an appropriate amount of water is added or no addition is performed for 180 days. The culture was continued. Regarding the morphological analysis of humic acid, the RF value was determined in the same manner as in Example 1, and the pH value was measured on 0 day, 50 day, 90 day, 120 day,
The results were shown in Table 2 on days 150 and 180, respectively. The extraction solvent for humic acid is 0-
180 days, all done with NaOH, 180
Regarding the day, the measurement results of the RF value using pyrophosphoric acid as the extraction solvent were also described as needed.

[0046]

[Table 2]

As is clear from the results in Table 2, when heat culturing was carried out without addition of coal ash as in Comparative Example 2, 180
The pH value is within a good range (pH 3 to 8) during the culture period for one day.
However, the RF value increased to the B-type humic acid in the early stage of the experiment, but there was no tendency to increase even after 50 days, and it did not reach the A-type humic acid.

In Comparative Examples 3 to 5, the culture temperature was 75.
Since the temperature was a low temperature outside the predetermined range of ° C, the RF value was as low as less than 23 even after 180 days.

In Comparative Example 6 in which coal ash (pH value was about 12) was used without any pH adjustment, the pH value gradually decreased as the heating culture period passed.
Since the value was high, the RF value was as low as less than 33 even after 180 days, and the A-type humic acid was not produced.

Further, in Comparative Example 7 in which no water was supplied to the mixture during the culturing period, the pH value was significantly increased, and as a result, the humic acid denaturation was inhibited and the RF value was a low value of less than 12. And the A-type humic acid was not produced.

In contrast to the results of the comparative example as described above, Examples 3 and 4 satisfying the predetermined conditions have p values during the heating culture period.
It can be seen that the H value is in the range of 3 to 8 and the RF value on the 180th day exceeds 80, and the humus contains A-type humic acid.

[0052]

Industrial Applicability As described above, the present invention provides a humic acid soil improving material which mixes an organic carbon source with coal ash having a predetermined pH value and produces A-type humic acid by thermochemical reaction while adding water. Since the production method is used, there is provided a new application for effective use of coal ash, and there is an advantage that a soil improving material containing A-type humic acid can be efficiently produced in the shortest possible time.

By this method, A-type humic acid, which also contributes to the suppression of the release of carbon dioxide, which is said to be the main cause of global warming, into the atmosphere is fixed, and a useful soil improvement material is newly developed. There is also an advantage that various manufacturing methods are provided.

[Brief description of drawings]

FIG. 1 is a chart showing a relationship between an RF value and a Δlog K value for each test day in Example 1.

FIG. 2 is a chart showing the relationship between the RF value and Δlog K value for each test day in Example 2.

FIG. 3 is a chart showing the relationship between the RF value and Δlog K value for each test day in Comparative Example 1.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C09K 17/32 C05F 11/04

Claims (3)

(57) [Claims] 1. A type humic acid is obtained by adding and mixing coal ash adjusted to a pH value of 4 to 6 to an organic carbon source, adding water to this mixture, and performing a thermochemical reaction under the condition of heating at 90 ° C. or higher. A method for producing a humic acid soil amendment material, which comprises degrading to a humic acid soil containing water. 2. The method for producing a humic acid soil amendment material according to claim 1, wherein the mixing ratio of the coal ash and the carbon source is in the range of 1: 5 to 5: 1 (weight ratio). 3. The method for producing a humic acid soil amendment material according to claim 1, wherein the mixture is subjected to a thermochemical reaction at a pH value of 3 to 8.