JP6021182B2 - Method for producing a bitter earth phosphate fertilizer - Google Patents

Description

The present invention relates to a manufacturing method of magnesia phosphate manure, in particular, phosphorus relates how you produce magnesia phosphoric fertilizer with included in sludge from sewage treatment plants or human waste treatment facilities.

  Phosphorus, one of the three elements of fertilizer, depends on phosphate ore for its raw material, and in Japan, where mineral resources are scarce, all of it is imported. Phosphorite ore is expected to be depleted in the future and may become extremely difficult to obtain in the future. How to efficiently recover high-quality phosphorus from sewage containing a large amount of phosphorus, or recycle it Kaga has become a challenge for technological development in Japan.

  Some of Japan's sewage treatment facilities have melting furnaces that add a calcium source or magnesium source to the sewage dewatered sludge to control the melting temperature to form molten slag. However, this molten slag is not intended to be used as fertilizer, but is intended to be used as civil engineering materials such as roadbed materials, or simply to reduce the volume to reduce the final disposal amount. The above problem of use is not considered at all.

  Therefore, for the purpose of fertilization, for example, Patent Document 1 uses, as a raw material, sludge containing phosphorus or other incinerated ash, and an additive containing magnesium oxide, calcium oxide, phosphoric acid or other components in the raw material. A method for producing a fertilizer is described, which includes a step of adding to form a mixed raw material, melting the mixed raw material, and then rapidly cooling to slag and pulverizing.

JP 2001-80979 A

  However, in the fertilizer manufacturing method described in the above-mentioned patent document, an incineration step for converting dehydrated sludge into incineration ash and a melting step for melting into fertilizer are required. For this reason, a large amount of heat energy is required, resulting in a problem that the manufacturing cost increases.

  Then, this invention is made | formed in view of the said solution subject, Comprising: The phosphorus contained in a sewage sludge or a human waste sludge is used effectively, and manufactures a high-quality fertilizer, especially a bitumen phosphate fertilizer at low cost. For the purpose.

In order to achieve the above object , the present invention is a method for producing a bituminous phosphate fertilizer, which is incinerated or fired when sewage sludge or human waste sludge is incinerated or fired at 950 ° C. or higher and 1100 ° C. or lower . Alternatively, a magnesium source is added to the sewage sludge or human waste sludge so that the MgO concentration of the fired product is 10% by mass or more and 25% by mass or less .
According to the present invention, soluble by the addition of magnesium sources, 950 magnesium calcium and alkaline earth phosphates phosphoric acid is produced at a low temperature incineration or firing ° C. or higher 1100 ° C. or less, the two components of phosphate and verbosity It is possible to produce a fed-battery phosphate fertilizer, and by using an incineration or firing process whose treatment temperature is lower than that of melting, energy consumption can be reduced and production costs can be greatly reduced.

Furthermore, the material to be incinerated or fired product of MgO concentration of 10 mass% or more, more preferably by a on 15% by mass or can generate a good mineral availability supply of phosphate and verbosity. Therefore, incinerated products or calcinations with a high solubility of phosphoric acid (ratio of soluble phosphoric acid in the phosphorus content) and a high dissolution rate of magnesia (ratio of soluble magnesia in the magnesium content) You can get things. On the other hand, if the MgO concentration of the incinerated product or the calcined product is higher than 25% by mass, the calcining temperature rises, and the amount of mineral that is poor in availability of bitter soil increases, which is not preferable.

Further, in the above method for producing a maternal phosphate fertilizer, the magnesium is added to the sewage sludge or human waste sludge so that the P / Si molar ratio of the sewage sludge or human waste sludge to which the magnesium source is added is 0.7 or more. Sources can be added.
Furthermore, the sewage sludge or human waste sludge to which the magnesium source is added can be subjected to solid-liquid separation, and the dewatered sludge obtained by the solid-liquid separation can be incinerated or fired. Thereby, the sewage sludge or human waste sludge with a high moisture content can be processed efficiently.
The sewage sludge or human waste sludge can be subjected to solid-liquid separation, and the magnesium source can be added to the dewatered sludge obtained by the solid-liquid separation. Thereby, the sewage sludge or human waste sludge with a high moisture content can be processed efficiently.
Furthermore, the magnesium source may have an average particle size of 100 μm or less . If the average particle size of the magnesium source MA is larger than 100 μm, unreacted magnesium remains in the maternal phosphate fertilizer, and the dissolution rate may decrease.

  The magnesium source is a storage tank for storing the sewage sludge or human waste sludge, a solid-liquid separator for solid-liquid separation of the sewage sludge or human waste sludge from the storage tank, and a sludge connected to an inlet of the solid-liquid separator. It can be added to at least one location selected from a transport means, an incinerator for incinerating or firing the dewatered sludge discharged from the solid-liquid separator, or a dehydrated sludge transport means connected to the inlet of the firing furnace.

As described above, according to the manufacturing how the magnesia phosphate fertilizer according to the present invention, it is possible to produce the magnesia phosphate fertilizer at low cost from sewage sludge or night soil sludge.

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram which shows the sewage treatment facility to which the manufacturing method of the maternal phosphate fertilizer which concerns on this invention is applied .

  Next, an embodiment for carrying out the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a sewage treatment facility to which the method for producing a maternal phosphate fertilizer according to the present invention is applied . The sewage treatment facility 1 is roughly divided to concentrate sewage S1 brought into the sewage treatment facility 1 for dehydration. Water treatment equipment 2 that separates into sludge S9 and dehydrated filtrate W3, and magnesium source MA is added to the dewatered sludge S9 separated in the water treatment equipment 2 and incinerated, and the incinerated product I is pulverized and granulated. It consists of a mixed incineration facility 4 for obtaining soil phosphate fertilizer F.

  The water treatment facility 2 concentrates the suspended matter and mud MU that easily settle in the sewage S1 and sends them to the gravity concentration tank 12, and the organic matter, nitrogen, phosphorus from the first precipitation basin 5 after finishing the precipitation treatment. A biological treatment tank 6 for treating sewage S2 containing microorganisms with microorganisms, etc., a final sedimentation tank 7 for precipitating activated sludge S3 treated in the biological treatment tank 6 over time, and discharging supernatant water D, and final precipitation Centrifugal concentrator 8 for further concentrating surplus sludge S4 from pond 7 by centrifugal force, methane fermentation tank 9 for decomposing concentrated sludge S5 from centrifugal concentrator 8 and concentrated sludge S6 from gravity concentrator tank 12, and methane fermentation The storage tank 10 stores the sludge S7 discharged from the tank 9, and the solid-liquid separator 11 that separates the sludge S8 discharged from the storage tank 10 into the dehydrated sludge S9 and the dehydrated filtrate W3.

  The mixed incineration facility 4 includes a magnesium source addition device 13 that adds the magnesium source MA to the dehydrated sludge S9 separated by the water treatment facility 2, a mixer 14 that mixes the dehydrated sludge S9 and the magnesium source MA, and a mixer 14 A stalker furnace 15 for incinerating the mixture M supplied from the slab, a pulverizer 16 for pulverizing the incinerated product I to a desired size, and a granulation by adding the granulation aid A to the pulverized incinerated product I It consists of a granulator 17.

  The magnesium source addition device 13 is provided to add the magnesium source MA to the dewatered sludge S9. The magnesium source addition device 13 includes the properties of the magnesium source MA added from various devices for supplying the powder particles. Choose the right one for you.

  The stalker furnace 15 is incinerated while allowing the mixture M to flow down from an upper part to an inclined grate, and generally has a grate that has a stepped shape and slides back and forth. . As the stalker furnace 15, an existing sewage treatment facility or the like can be used as it is or after being modified. Further, instead of the stalker type furnace, a rotary type or fluidized bed type incinerator can be used. The incinerator preferably has a brick lining having a fireproof temperature of 900 ° C. or higher, and the existing one may be modified if necessary.

  The pulverizer 16 is provided for pulverizing the incinerated material I, and it is preferable to use a jaw crusher, a hammer crusher, a ball mill, a vibration mill, a disk mill or the like. A general-purpose vibrating screen or airflow classifier can be used together with the pulverizer 16.

  The granulator 17 is provided to granulate by adding the granulation auxiliary A to the incinerated material I, and includes a pan pelletizer, a bread type mixer, a stirring granulator, a briquette machine, a roll press, an extrusion molding machine, and the like. Can be used.

  Next, a method for producing a bitumen phosphate fertilizer in the sewage treatment facility 1 will be described with reference to FIG.

  The sewage S1 that has flowed into the sewage treatment facility 1 is guided to the first settling basin 5, and the suspended matter and mud MU that are likely to settle in the first settling basin 5 are concentrated and sent to the gravity concentration tank 12, and the sewage S2 containing organic matter is biologically It supplies to the processing tank 6 and processes with microorganisms.

  The activated sludge S3 generated in the biological treatment tank 6 is precipitated in the final sedimentation tank 7 over time, and the precipitated sludge is supplied to the centrifugal concentrator 8 as surplus sludge S4, and the supernatant obtained in the final sedimentation tank 7 is supplied. Release water D. A part of the excess sludge S4 is usually returned to the biological treatment tank 6.

  Excess sludge S4 from the final sedimentation basin 7 is concentrated by the centrifugal concentrator 8 and supplied to the methane fermentation tank 9 together with the concentrated sludge S6 stored in the gravity concentration tank 12. In the methane fermentation tank 9, the concentrated sludges S5 and S6 are decomposed by microorganisms, and the generated sludge S7 is temporarily stored in the storage tank 10, and then the sludge S8 is supplied to the solid-liquid separator 11 for solid-liquid separation and dewatered sludge S9. Manufacturing. The solid-liquid separator 11 can be a belt press, a belt filter, a decanter, a screw press, or a filter press.

  Next, the magnesium source MA is added to the dehydrated sludge S9 by the magnesium source addition device 13. The magnesium source MA is added to produce a bituminous phosphate fertilizer that can supply two components of phosphoric acid and bitter earth even at low temperature incineration or baking at 950 ° C. or higher and 1100 ° C. or lower. The magnesium oxide content of the phosphate fertilizer is adjusted to 10% by mass to 25% by mass.

  It is also possible to provide a dryer that reduces the water content of the dewatered sludge and the mixture M separated by the solid-liquid separator 11. The moisture content can be reduced to preferably 50% or less by the drying, and the input energy for incineration or calcination is further reduced, and the temperature of the incinerated product itself rises during incineration. It becomes easy to produce minerals with excellent properties. As the dryer, a general-purpose dryer can be used, and as a heat source, sunlight, incineration or calcination exhaust gas, hot air generated separately, or the like can be used.

  Examples of the magnesium source MA to be added include at least one selected from magnesium carbonate, basic magnesium carbonate, magnesium oxide, magnesium hydroxide, dolomite, and dolomite brick waste.

  Further, the magnesium source MA may be pulverized to an average particle size (50% passing particle size) of 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less. If the average particle size of the magnesium source MA is larger than 100 μm, unreacted magnesium remains in the maternal phosphate fertilizer, and the dissolution rate may decrease.

In addition to the magnesium source MA, a silica source may be further added. In general, sewage sludge contains a large amount of silicon (SiO ₂ ), so there are few cases where a silica source is added. However, it is necessary to supplement the silica source when the silicon content of the sewage sludge is low, although it is desired to provide silicic acid supply. . Examples of the silica source in this case include at least one selected from silica, silica sand, sand, diatomaceous earth, shirasu, raw conslag, waste mortar, waste concrete, acidic volcanic ash, acidic volcanic rock, and calcium silicate.

  Next, the dewatered sludge S9 and the magnesium source MA are supplied to the mixer 14 and mixed, and the homogenized mixture M is supplied to the stalker furnace 15 and incinerated. The incinerated product discharged from the stalker furnace 15 is a lump having a particle size of about 1 mm for a small one and about 8 cm on average for a small one. Since this particle size cannot be distributed as a fertilizer product, the particle size range is roughly pulverized by a pulverizer 16 so that the particle size range is between 1 mm and 5 mm, and sized by sieving or the like. A commercially available vibration sieving device can be used as the sizing device. What is sized in this range can be fertilized directly to agricultural land as phosphate fertilizer.

  In addition, the coarsely pulverized product or the incinerated product I which has been finely pulverized until the average particle size becomes 100 μm or less is granulated together with a granulation auxiliary material, and a desired particle size range by sizing operation. A fertilizer that can be directly applied to agricultural land can also be obtained by a method of selecting the ones.

  Granulation molding is carried out together with the granulation auxiliary agent A by a subsequent granulator 17 so as to obtain a desired size. For the granulation aid A, lignin, polyvinyl alcohol, methylcellulose and the like can be used. Moreover, in this process, depending on the use of the fertilizer, components of silicic acid and phosphoric acid can be added as appropriate, and other fertilizer components such as nitrogen, potassium and bitter earth can be newly added.

  The granulation molding and sizing process is necessary to adjust the particle size of the fertilizer in order to suppress the generation of dust and facilitate the handling of the fertilizer when fertilizing agricultural land, and to fully demonstrate the fertilizer effect It is an optional step that is selected if there is.

  In the above embodiment, the dewatered sludge S9 and the magnesium source MA are supplied to the mixer 14 and mixed, and the homogenized mixture M is supplied to the stalker furnace 15 and incinerated. However, the mixer 14 is provided. Without being added directly to the solid-liquid separator 11 or to the sludge transport means connected to the inlet of the solid-liquid separator 11, that is, the sludge S8 between the storage tank 10 and the solid-liquid separator 11, In this case, the magnesium source MA is also subject to solid-liquid separation by the solid-liquid separator 11, but an increase in the load of the solid-liquid separator 11 is a problem considering the amount of magnesium source MA added and the moisture content of the sludge S8. Not so much.

  Further, a phosphorus recovery material is added to the storage tank 10, a phosphorus recovery material is added to the dehydrated filtrate W3, and a phosphorus recovery material adsorbing phosphorus is obtained by solid-liquid separation. And the magnesium source MA together with the magnesium source MA, the mixture M may be incinerated in the stalker furnace 15.

  As the phosphorus recovery material, a recovery material containing calcium, for example, amorphous calcium silicate can be preferably used. Amorphous calcium silicate has high affinity with phosphorus, is porous, has a specific surface area. Since it is large, it has a high phosphorus adsorption capacity and can selectively and efficiently adsorb phosphorus. In addition, calcium hydroxide, calcium chloride, magnesium oxide, magnesium hydroxide, magnesium chloride, and the like can be used.

  Moreover, in the said embodiment, although the mixture M supplied from the mixer 14 was incinerated with the stalker furnace 15, you may bake with a rotary type or a fluid bed type incinerator. When a fluidized bed furnace is used instead of the stalker furnace 15, the magnesium source MA can be added to the dewatered sludge transport means connected to the inlet of the fluidized bed furnace, or the magnesium source MA can be added directly to the fluidized bed furnace. When incinerated in a fluidized bed furnace, unlike the case of incinerating in a stalker furnace, the magnesium source MA is in a uniformly mixed state, so the mixer 14 is not necessary.

  Furthermore, instead of incinerating in these types of furnaces, the mixture M may be fired using these as a firing furnace. Even in the case of firing, the fired product is pulverized by the subsequent pulverizer 16 and further granulated and molded to a desired size together with the granulation auxiliary agent A by the granulator 17 to produce a clay clay phosphate fertilizer. You can also

In the said embodiment, although the case where the manufacturing method of the maternal phosphate fertilizer based on this invention was applied to the sewage treatment facility was demonstrated, it can also be applied to a human waste treatment facility.

  The human waste treatment facility is different from the sewage treatment facility in that it includes a denitrification tank and a nitrification tank for performing denitrification of human waste, but other devices are common to the sewage treatment facility. Therefore, although not shown in the drawings, even in the human waste treatment facility, the bitumen phosphate fertilizer can be manufactured by the same apparatus configuration and operation procedure as the sewage treatment facility 1.

  In addition, since there is no mixing of land soil components, human waste is poor in silica and alumina in the ash incinerated with human waste, but according to the present invention, it is possible to obtain a bitumen phosphate fertilizer in the same manner as sewage sludge. .

  Using the sewage sludge incineration ash (A, B, C, E) having the chemical composition shown in Table 1 as urine sludge (D), and magnesium hydroxide as a reagent as a magnesium source, Examples and Comparative Examples shown in Table 2 A raw material was prepared by mixing in a plastic bag according to the formulation. Next, the raw material was molded by a uniaxial pressure molding machine to produce a cylindrical raw material having a diameter of 15 mm and a height of 20 mm. Further, after the cylindrical raw material is placed in an electric furnace, the temperature is raised to a temperature shown in Table 2 at a temperature rising rate of 20 ° C./min, and baked for 10 minutes at the temperature to obtain a fired product. It was. Further, the fired product was pulverized using an iron mortar until it passed through a sieve having an opening of 212 μm, to produce a powdery clay earth phosphate fertilizer. As a comparative example, phosphoric acid fertilizer was produced by the same method as described above using calcium carbonate having a purity of 99% as a raw material instead of the magnesium source. The quantification of oxides in the raw material and the maternal phosphate fertilizer was performed by a fundamental parameter method using a fluorescent X-ray apparatus. The soluble phosphoric acid in phosphate fertilizer is measured by the ammonium vanadomolybdate method specified in the fertilizer analysis method (Agricultural and Environmental Technology Research Institute, Ministry of Agriculture, Forestry and Fisheries). Measured by atomic absorption spectrophotometry as defined in 1. Further, using these measured values, the solubility of phosphoric acid and the solubility of bitter earth were calculated by a conventional method.

As shown in Table 2, in each example, the fired product was fired at a MgO concentration of 10 mass% to 25 mass% and a firing temperature of 950 ° C. to 1100 ° C. It can be seen that a high rate of mafic phosphate fertilizer is obtained. In particular, a preferable result is obtained when the P / Si molar ratio of the raw material is set to 0.7 or more. On the other hand, in the comparative example, Ca (OH) ₂ was added to the sludge incinerated ash indicated by symbol B, and calcined at a higher addition amount and higher temperature of 1200 ° C. than the magnesium source. In addition, it has not been possible to burn a bitter clay phosphate fertilizer having a high dissolution rate.

A sewage treatment plant with a planned treatment population of 450,000 employs a sewage draining method (partially combined), and the treatment method is the standard activated sludge method. In the sewage treatment plant A, sewage of 80,000 m ³ per day flows in, and the sludge in the first sedimentation basin (primary sludge) and the sludge in the final sedimentation basin (surplus sludge) are mixed in a gravity concentration tank, and 700 m ³ per day. Is sent to the subsequent concentrated sludge storage tank. The concentrated sludge is extracted at 30 m ³ per hour, and after the polymer flocculant is added in the flocculant addition tank, the sludge is fed to the subsequent solid-liquid separator and separated into dehydrated sludge and dehydrated filtrate. The solid content concentration of the concentrated sludge was 1.9%.

  In this example, 23.2 kg of lightly burnt magnesite powder (325 mesh product, average (medium) particle size of 8 μm, 90% passing particle size of 35 μm) of 23.2 kg per hour was added to the flocculant addition tank. A molecular flocculant was added to perform a solid-liquid separation operation. The dewatered sludge (water content 80%) generated in the solid-liquid separation is dried to a water content of 40% with a paddle type agitation dryer, and is connected to a stalker incinerator (furnace width 1.5 m × length 3. 5M) and supplied at 350 kg per hour, and incinerated under the conditions of a maximum temperature in the furnace of 950 ° C. (incinerator temperature is 1000 ° C. in the measurement using a thermocouple). The oxygen concentration of the combustion exhaust gas was 5%, and the average residence time was about 60 minutes. The chemical composition of the incinerated ash collected in advance was as shown in Table 3.

  The incineration temperature is different from the temperature of the incinerator, and the normal temperature of the stalker furnace is 900 to 950 ° C., which often refers to the combustion chamber temperature and the outlet temperature, and the temperature of the incinerator is actually 950 ° C. The fertilizer shown in the present application is obtained.

  Table 4 shows the characteristics of the fertilizer obtained by the incineration. In this example, the soluble phosphoric acid was 19.4% by mass, and the phosphoric acid solubility was 72%. Further, the soluble clay was 18.8% by mass, and the dissolution rate of the clay was 94%. Thus, according to the present invention, it was shown that a phosphate fertilizer excellent in elution characteristics of phosphoric acid and bitter earth can be produced.

  As mentioned above, although the Example and comparative example of this invention were described, the concrete structure is not restricted to this Example, The design change etc. of the range which does not deviate from the summary of this invention may be sufficient.

1 Sewage treatment facility 2 Water treatment facility 4 Mixed incineration facility 5 First sedimentation tank 6 Biological treatment tank 7 Final sedimentation tank 8 Centrifugal concentrator 9 Methane fermentation tank 10 Storage tank 11 Solid-liquid separator 12 Gravity concentration tank 13 Magnesium source addition device 14 Mixing Machine 15 Stoker furnace 16 Crusher 17 Granulator

Claims (6)

When sewage sludge or human waste sludge is incinerated or calcined at 950 ° C. or higher and 1100 ° C. or lower, the sewage sludge is adjusted so that the MgO concentration of the incinerated product or calcined product generated by the incineration or calcining is 10% by mass or more and 25% by mass or less. Alternatively, a method for producing a maternal phosphate fertilizer, characterized by adding a magnesium source to human waste sludge . The magnesium source is added to the sewage sludge or human waste sludge so that the P / Si molar ratio of the sewage sludge or human waste sludge to which the magnesium source is added is 0.7 or more. The manufacturing method of the bitter-earth phosphate fertilizer of description. Solid-liquid separation of the sewage sludge or human waste sludge added with the magnesium source,
3. The method for producing a bituminous phosphate fertilizer according to claim 1 or 2, wherein the dewatered sludge obtained by the solid-liquid separation is incinerated or calcined. Solid-liquid separation of the sewage sludge or human waste sludge,
3. The method for producing a bituminous phosphate fertilizer according to claim 1 or 2, wherein the magnesium source is added to the dewatered sludge obtained by the solid-liquid separation. The said magnesium source is 100 micrometers or less in average particle diameter, The manufacturing method of the bituminous-phosphate fertilizer in any one of the Claims 1 thru | or 4 characterized by the above-mentioned. A storage tank for storing the sewage sludge or human waste sludge, a solid-liquid separator for solid-liquid separation of the sewage sludge or human waste sludge from the storage tank, and a sludge transporting means connected to the inlet of the solid-liquid separator. , claim 1, characterized in that the addition of at least one location selected from dewatered sludge transport means connected to the inlet of the incinerator or a baking furnace to burn or firing dewatered sludge discharged from the solid-liquid separator The manufacturing method of the bitter-earth phosphate fertilizer in any one of thru | or 5 .

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