JP2019073415A - Method of producing soil material derived from incinerated ash of organic waste - Google Patents

Abstract

To provide a method of producing a soil material with increased value as a phosphorous material by increasing a present amount of phosphorus in incinerated ash of organic waste that can be used by plant bodies.SOLUTION: A method of producing a soil material includes: an acid treatment step of blending incinerated ash of organic waste and 10%-80% sulfuric acid with a liquid/solid ratio of 2.0 or less and an adjustment step of blending the muddy or wet powdery substance obtained in the previous step and a calcium source.SELECTED DRAWING: None

Description

  The present invention relates to a method of producing a soil material derived from incineration ash of organic waste.

  For plants, phosphorus is an essential nutrient and in the absence of sufficient phosphorus in the soil it is necessary to fertilize lime phosphate or superphosphate lime fertilizer.

On the other hand, superphosphate lime in the fertilizer category is registered as phosphate lime containing residues and byproducts simply by mixing sulfuric acid with phosphate ore.
This method has the advantage that low cost materials can be provided without a filtration step. However, phosphorus contained in superphosphate lime is water-soluble phosphorus, and when it is used as it is in agricultural land, it is eluted in the soil and immobilized in the soil component to be insolubilized, so that the efficiency of being taken into the plant is low. Therefore, it is recommended to use it in combination with phosphorus materials that have a slow-acting effect and are insoluble in water.

On the other hand, phosphorus resources are finally concentrated in sewage treatment plants according to human activities, and finally concentrated and accumulated in incineration ash in sewage treatment. The incineration ash of municipal sewage has reached a P ₂ O ₅ concentration of around 40%.

  Therefore, acid treatment with sulfuric acid, organic acid and the like, and alkali treatment with caustic soda etc. have long been considered as a method of recovering phosphorus in sewage sludge incineration ash (for example, Patent Document 1). In these processes, phosphorus contained in incineration ash is extracted as phosphoric acid, and this extract is subjected to solid-liquid separation from the residue, and then, phosphoric acid is reacted with a calcium source to crystallize as calcium phosphate (for example, Patent Document 2) ).

Japanese Patent Application Laid-Open No. 11-278814 JP, 2012-144381, A

The method of Patent Document 2 is complicated because it requires a solid-liquid separation step, and it can be evaluated that it is not an economical method.
According to the method of Patent Document 1, the phosphorus component can be eluted while promoting the elution of calcium while the solid-liquid ratio is 0.04 g / ml or less.
However, although Patent Document 1 discloses that the solid-liquid ratio is related to the elution of calcium and the elution of the phosphorus component, there is no suggestion to predict the low liquid-solid ratio of the present invention.

  Therefore, the main object of the present invention is to provide a production method which increases the amount of phosphorus available to plants in the incineration ash of organic waste, thereby enhancing the value as a phosphorus material. Another object is to provide an economical manufacturing method that has a simple manufacturing process.

The method for producing a soil material derived from incineration ash of organic waste according to the present invention, which solves the above problems, comprises the incineration ash of organic waste and sulfuric acid with a concentration of 10% to 80% at a liquid-solid ratio of 2.0. An acid treatment step to be mixed below,
An adjustment step of mixing the mud-like or wet powdery substance thus obtained with a calcium source;
It is characterized by having.
Here, the liquid-solid ratio means the mass (g / g = kg / kg) of sulfuric acid solution per unit mass of incinerated ash of organic waste.

  Acid treatment with a liquid-solid ratio of 2.0 or less, more preferably 1.5 or less, particularly preferably 1.0 or less according to the present invention can increase the amount of phosphorus available to the plant.

  The acid treatment step can be performed for 1 hour or less, and the production time is high because of the short acid treatment time.

The acid treatment step and the adjustment step can be performed in the same vessel. In addition to achieving reduction of equipment cost, processing time is shortened.
It is also possible to transfer the acid-treated product to the adjustment process equipment and carry out the adjustment process, with the acid treatment process and the adjustment process as separate processes.

  Further, in the adjustment step, it is desirable to perform mixing and granulation of the substance in the form of a mud or wet powder obtained in the acid treatment step and a calcium source from the viewpoint of shortening the treatment time and the like.

  Furthermore, it is desirable for supplying phosphorus to a plant body as a soil material to obtain a granulated product of 5 mm or less in the adjustment step.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes the manufacturing method which raises the abundance of the phosphorus which can be utilized for the plant body in the incineration ash of organic waste, and thereby enhances the value as a phosphorus material. In addition, the manufacturing process is simple, which results in an economical manufacturing method.

It is a figure concerning the present invention. It is a photograph which shows the external shape of the material obtained by the Example.

  Hereinafter, embodiments of the present invention will be described in detail.

  The present invention uses organic ash incineration ash as a raw material. As the incineration ash of the organic waste, for example, a residue obtained by dewatering the sludge of urban sewage and incinerating it can be mentioned. It may be incinerated ash of food residue, manure and animal feces, or incineration ash mixed with food residue, manure and faeces to urban sewage can also be used.

  Sulfuric acid is added to the incinerated ash of the organic waste to carry out acid treatment. As the acid, phosphoric acid and the like are also conceivable, but in view of high reaction rate, sulfuric acid, preferably 10 to 80% sulfuric acid is used.

The acid treatment step is a step of mixing incineration ash of organic waste and sulfuric acid having a concentration of 10% to 80% at a liquid-solid ratio of 2.0 or less. The liquid-solid ratio means the mass (g / g = kg / kg) of sulfuric acid solution per unit mass of incinerated ash of organic waste.
The contact between sulfuric acid and incineration ash preferably has a liquid-solid ratio of 0.5 or more and 2.0 or less. Preferably, it is in the range of 0.6 to 1.0. The amount of sulfuric acid added is, for example, in the range of 10 to 70% by mass, preferably 10 to 40% by mass, with respect to the incinerated ash. The concentration of sulfuric acid is necessarily determined by the liquid-solid ratio and the amount of sulfuric acid added to the incinerated ash.
In addition, when mixing incineration ash and sulfuric acid having a concentration of 10 to 80%, a predetermined amount of water may be added to the incineration ash first, and then a predetermined amount of 98% sulfuric acid may be added.

  In this acid treatment step, for example, incineration ash of organic waste and sulfuric acid can be sequentially or simultaneously introduced into a stirring tank to perform stirring and mixing.

  An acid treatment process can be made into 1 hour or less. Extraction of phosphorus is possible in 5 minutes-1 hour of mixing, for example, extraction of phosphorus can be satisfied even if reaction time is about 10 to 30 minutes by stirring and mixing. Moreover, you may leave still for a fixed time, after stirring and mixing. For example, stirring and mixing may be performed for 10 minutes and then left to stand for 50 minutes. In addition, it is possible to shorten the stirring time by grinding in advance.

It has the adjustment process of mixing the mud-like or wet powdery substance obtained by this and a calcium source. For example, mixing can be performed while maintaining fluidity by mixing while performing stirring, vibration, and the like.
Also, the acid treatment step and the adjustment step can be performed in separate containers, or can be performed in the same container. It is desirable to carry out in the same vessel to reduce the cost of equipment and shorten the processing time.

In the adjustment step, mixing and granulation of the mud-like or wet powdery substance obtained in the acid treatment step and the calcium source can be performed. For example, by using a mixer or the like, a granulated product can be obtained in combination with the mixing thereof.
In addition, in the adjustment step, a granulated product of 5 mm or less can be obtained. It is desirable for supplying phosphorus to a plant body as a soil material that the granulated material be 5 mm or less.

Although not limited to the type of calcium source in the present invention, slaked lime is desirable.
Quicklime is difficult to handle because it reacts exothermically and hardens too quickly. Other usable calcium sources include common portland cement, calcium chloride, calcium carbonate, paper sludge incinerator ash and the like.

The calcium source to be added to this acid-treated ash is preferably slaked lime, and by mixing the calcium source with the acid-treated ash slurry, the water adjustment proceeds and at the same time the reaction between calcium and anions such as phosphate ion and sulfate ion As a result, gypsum, calcium phosphate or the like is produced, which serves as a linking agent to promote granulation.
A predetermined granulated product can be obtained by performing the pulverizing process and the water adjustment simultaneously with the kneading operation. Therefore, it can also be set as the manufacturing process which does not provide a filtration process and a solid-liquid separation process. When the filtration step and the solid-liquid separation step are not provided, the manufacturing process is simplified and the manufacturing method becomes more economical.
Water adjustment can be done by hydration or mixing silica components such as silicic acid and incinerated ash.
In addition, the product pH value can be arbitrarily adjusted from acidity to alkalinity by adjusting the addition amount of the calcium source.

  In order to adjust the particle size of the manufactured product, it is also possible to adjust the product particle size by providing a sieving machine and further a crusher in the latter stage.

Example 1
A sulfuric acid solution with a weight ratio of 40% by mass is added to 30 g of incinerated ash discharged at a sewage treatment plant in the Kanto region, a sulfuric acid solution is adjusted to a liquid-solid ratio of 1, and the mixture is stirred and mixed with the incinerated ash Let stand (total of 60 minutes for mixing and standing).
Thereafter, 10 g of slaked lime was added and mixed, and the stirred and granulated for 5 minutes was discharged.
This material is click-soluble phosphate _{(C-P 2 O 5)} 15.2 % by weight, soluble phosphate _{(S-P 2 O 5)} 15.4 % by weight, a water-soluble phosphate (W-P ₂ O ₅ 2) containing 0.2% by mass, the external shape of which is shown in FIG.
The total phosphoric acid (T-P ₂ O ₅ ) in this modified ash is 22.4%, and the solubility ratio = P ₂ O ₅ / T-P ₂ O ₅ = 68%.
Thereafter, the pH value of the solution reslurried with 300 g of pure water was 9.
In the case of using fertile phosphorus and fertilizer based on the fertilizer control method to this material, a Cu-soluble magnesia, a soluble silicic acid may be separately added, or may be added and mixed in advance in a mixing step.

(Example 2)
Sulfuric acid was added at a weight ratio of 56% by mass to 10 g of the incinerated ash, and the sulfuric acid solution was adjusted to a liquid-solid ratio of 2. After stirring and mixing with the incinerated ash, the mixture was allowed to stand (total of 60 mixture and standing). Minutes).
Thereafter, 4.6 g of slaked lime was added and mixed, and the stirred granulated for 5 minutes was discharged.
Click-soluble phosphate _{(C-P 2 O 5)} 16.2 % by weight, the total phosphate improvements in ash (T-P ₂ O ₅₎ is 18.5%, click-soluble ratio = P ₂ O ₅ / T-P ₂ became the O ₅ = 87%.

(Example 3)
Sulfuric acid was added at a weight ratio of 20% by mass to 10 g of the incinerated ash, and the sulfuric acid solution was adjusted to have a liquid-solid ratio of 1. After stirring and mixing with the incinerated ash, the mixture was allowed to stand (mixed and stationary 60 minutes in total) ).
Thereafter, 1.7 g of slaked lime was added and mixed, and the stirred granulated for 5 minutes was discharged.
12.7% by mass of liposoluble phosphoric acid (C-P ₂ O ₅ ), the total phosphoric acid (T-P ₂ O ₅ ) in this modified ash is 26.1%, and the solubility ratio = P ₂ O ₅ / T-P ₂ became the O ₅ = 49%.

(Example 4)
Sulfuric acid with a weight ratio of 40% by mass was added to 10 g of the incinerated ash, the sulfuric acid solution was adjusted to a liquid-solid ratio of 0.6, and after stirring and mixing with the incinerated ash, the mixture was allowed to stand (mixed and stationary total) 60 minutes).
Thereafter, 3.3 g of slaked lime was added and mixed, and the stirred granulated for 5 minutes was discharged.
Csoluble phosphoric acid (C-P ₂ O ₅ ) 14.0% by mass, total phosphoric acid (T-P ₂ O ₅ ) in this modified ash is 22.0%, and the solubility ratio = P ₂ O ₅ / T-P ₂ O ₅ = became 64%.

(Example 5)
Sulfuric acid with a weight ratio of 40% by mass was added to 20 g of the incinerated ash, the sulfuric acid solution was adjusted to a liquid-solid ratio of 0.6, and after stirring and mixing with the incinerated ash, the mixture was allowed to stand (mixed and stationary total) 60 minutes).
Thereafter, 3.3 g of slaked lime was added and mixed, and the stirred granulated for 5 minutes was discharged.
18.2% by mass of a fusible phosphoric acid (C-P ₂ O ₅ ), the total phosphoric acid (T-P ₂ O ₅ ) in this modified ash is 22.8%, and a solubility ratio = P ₂ O ₅ / T-P ₂ becomes O ₅ = 80%.

(Example 6)
A sulfuric acid solution with a weight ratio of 60% by mass was added to 20 g of the incinerated ash, the sulfuric acid solution was adjusted to a liquid-solid ratio of 0.8, and after stirring and mixing with the incinerated ash, it was allowed to stand 60 minutes).
Thereafter, 10 g of slaked lime was added and mixed, and the stirred and granulated for 5 minutes was discharged.
16.6% by mass of a hydrosoluble phosphoric acid (C-P ₂ O ₅ ), the total phosphoric acid (T-P ₂ O ₅ ) in this modified ash is 18.0%, and a solubility ratio = P ₂ O ₅ / T-P ₂ becomes O ₅ = 92%.

(Comparative example 1)
A sulfuric acid solution with a weight ratio of 56% by mass was added to 10 g of the incinerated ash, the sulfuric acid solution was adjusted to a liquid-solid ratio of 20, and after stirring and mixing with the incinerated ash, it was allowed to stand (mixing and stationary total 60 minutes ).
Thereafter, 4.6 g of slaked lime was added and mixed, and the stirred and mixed for 10 minutes was discharged.
The slurry was filtered and dried, and then the samples were determined to be soluble phosphoric acid and total phosphoric acid.
10.0% by mass of a fusible phosphoric acid (C-P ₂ O ₅ ), the total phosphoric acid (T-P ₂ O ₅ ) in this modified ash is 18.5%, and a solubility ratio = P ₂ O ₅ / T-P ₂ becomes O ₅ = 54%.

(Comparative example 2)
A sulfuric acid solution with a weight ratio of 20% by mass was added to 10 g of the incinerated ash, and the sulfuric acid solution was adjusted to a liquid-solid ratio of 20, and after stirring and mixing with the incinerated ash, it was allowed to stand (mixing and stationary total 60 minutes ).
Then, 1.66 g of slaked lime was added and mixed, and what was stirred and mixed for 10 minutes was discharged.
The slurry was filtered and dried, and then the samples were determined to be soluble phosphoric acid and total phosphoric acid.
(C-P ₂ O ₅ ): 9.6% by mass, the total phosphoric acid (T-P ₂ O ₅ ) in this modified ash is 26.1%, and the solubility ratio = P ₂ O ₅ / T-P ₂ becomes O ₅ = 37%.

  While showing the result of the said Example and comparative example in Table 1, it showed in FIG.

According to the fertilizer control method, fertile phosphorus fertilizer needs to contain 20% soluble phosphoric acid, 15% soluble magnesium and 20% soluble silica. Superphosphate lime should contain 18% soluble phosphoric acid and 15% water soluble phosphoric acid.
Therefore, the soil material according to the present invention may be adjusted as appropriate according to the purpose of the above-mentioned fertilizer.

Claims (5)

An acid treatment step of mixing organic waste incineration ash and sulfuric acid having a concentration of 10% to 80% at a liquid-solid ratio of 2.0 or less;
An adjustment step of mixing the mud-like or wet powdery substance thus obtained with a calcium source;
A method for producing a soil material derived from incinerated ash of organic waste, comprising:
Here, the liquid-solid ratio means the mass (g / g = kg / kg) of sulfuric acid solution per unit mass of incinerated ash of organic waste.   The manufacturing method of the soil material derived from the incineration ash of the organic waste of Claim 1 which makes an acid treatment process 1 hour or less.   The method for producing a soil material derived from incinerated ash of organic waste according to claim 1 or 2, wherein the acid treatment step and the adjustment step are performed in the same container.   The organic substance according to any one of claims 1 to 3, wherein the adjustment step is performed by mixing and granulating a substance in the form of a mud or wet powder obtained in the acid treatment step and a calcium source. Method of soil material derived from incineration ash of toxic waste.   The method for producing a soil material derived from incinerated ash of organic waste according to claim 4, wherein a granulated product of 5 mm or less is obtained in the adjusting step.