JP2000247616A - Equipment and method for recovering phosphorus from waste - Google Patents

Abstract

[PROBLEMS] To provide a facility and a method for recovering phosphorus from waste, which can increase the probability of contact between a phosphorus compound contained in the waste and carbon supplied from a carbon source. . The facility for recovering phosphorus from waste according to the present invention comprises:
A granulating means 31 for forming a granular material containing a waste containing phosphorus or a phosphorus compound and a carbon source; supplying the granular material from the granulating means 31; and heating the granular material under a reducing atmosphere. A heating furnace 1 for generating a high-temperature gas containing phosphorus vaporized by the above, and a phosphorus recovery means 12 for recovering the vaporized phosphorus from the high-temperature gas as yellow phosphorus or a phosphorus compound;
13, 20 to 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for recovering phosphorus from waste containing phosphorus or a phosphorus compound such as sewage sludge incineration ash.

[0002]

2. Description of the Related Art Conventionally, most waste such as sewage sludge has been disposed of by landfill after being incinerated. However, due to demands for effective use of resources and reduction of landfill disposal, some of such wastes are incinerated and then subjected to further melting treatment to insolubilize and stabilize heavy metals. It is being reused as such.

[0003] The incineration ash of the above waste is composed of oxides of various elements and contains phosphorus at a relatively high concentration. JP-A-9-145038 discloses a method for recovering phosphorus contained in this incinerated ash, and describes that the phosphorus recovered by this method can be reused as fertilizer and the like.

According to the method disclosed in Japanese Patent Application Laid-Open No. 9-145038, the recovery of phosphorus from waste incineration ash is performed as follows. First, waste incineration ash containing a phosphorus compound and a carbon source are supplied and melted in a closed electric furnace filled with reducing gas. Thereby, the phosphorus compound in the incinerated ash is reduced, and phosphorus gas is generated. next,
By bringing air into contact with the exhaust gas containing the phosphorus gas, phosphorus pentoxide is generated, and further, the exhaust gas containing the phosphorus pentoxide is brought into contact with water. As a result, the phosphorus pentoxide is absorbed by the water and produces phosphoric acid. That is, JP-A-9-14503
According to the method disclosed in Japanese Patent Publication No. 8 (1994) -86, phosphorus in the incinerated ash is recovered as phosphoric acid. Japanese Patent Application Laid-Open No. 9-145038 discloses that by condensing exhaust gas containing the above-mentioned phosphorus gas,
It also discloses recovering the phosphorus in the incineration ash as yellow phosphorus.

The above-mentioned method is effective in that phosphorus contained in incineration ash can be reused, but has the following problems. For example, in the melting treatment, a mixture of waste incineration ash and a carbon source is in a state of being accumulated on a molten slag layer in a melting furnace. This mixture gradually dissolves from the contact surface of the molten slag, but simply mixing the incineration ash with the carbon source will reduce the phosphorus compounds such as calcium phosphate and aluminum phosphate contained in the incineration ash and the carbon contained in the carbon source. Low contact angle ratio. Therefore, the reduction reaction rate of the phosphorus compound is slow, and the reaction hardly proceeds until the incinerated ash is converted into molten slag.

[0006] Further, the phosphorus compound is not reduced by carbon monoxide gas. Therefore, even if the carbon monoxide gas comes into contact with the mixture layer, no phosphorus gas is generated, and the mixture layer is directly melted in the molten slag. On the other hand, most of the carbon sources float on the molten slag without reacting when the incinerated ash is melted. For this reason, much of the phosphorus compound in the molten slag reacts with the carbonaceous brick that coats the inner wall of the electric furnace, rather than the carbon supplied from the carbon source.
As a result, according to the above-described method, the furnace wall is eroded, and frequent repairs have to be performed. As described above, the above-described method has a problem that the probability of contact between the phosphorus compound contained in the incineration ash and carbon supplied from the carbon source cannot be increased.

[0007] According to the above method, when incinerated ash is supplied into the electric furnace, dust rises in the furnace, and the dust is discharged from the electric furnace together with the exhaust gas. In particular,
Since incinerated ash such as sewage sludge is in the form of fine powder, the exhaust gas discharged from the electric furnace contains a high concentration of dust.

Some of such dust can be removed from the exhaust gas by an electric dust collector such as a Cottrell dust collector. However, since the dust is extremely fine, it is impossible to completely remove the dust with an electric dust collector.
Therefore, when the phosphorus gas contained in the exhaust gas is recovered as phosphoric acid or yellow phosphorus by the above-described method, dust cannot be mixed into the phosphoric acid or yellow phosphorus.

[0009] In the case of recovering the phosphorus gas contained in the exhaust gas as yellow phosphorus, the dust in the exhaust gas generates sludge in a condensing tower for condensing the exhaust gas, while recovering the phosphorus gas as phosphoric acid. First, sludge is generated in an absorption tower for absorbing phosphorus pentoxide into water. Such sludge contains a high concentration of phosphorus, and yellow phosphorus adheres to the sludge particularly when phosphorus gas is recovered as yellow phosphorus. Since yellow phosphorus ignites and smokes in the air, there is a problem that the cost for treating the yellow phosphorus contained in the sludge is separately required.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is possible to increase the probability of contact between a phosphorus compound contained in waste and carbon supplied from a carbon source. It is an object of the present invention to provide a facility and a method for recovering phosphorus from waste.

It is another object of the present invention to provide an apparatus and a method for recovering phosphorus from waste, which can reduce the cost for treating sludge and the like generated during the recovery of phosphorus.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a granulating means for forming a granular material containing a waste containing phosphorus or a phosphorus compound and a carbon source. A heating furnace for supplying the particulate matter and heating the particulate matter under a reducing atmosphere to generate a high-temperature gas containing phosphorus vaporized, and recovering the vaporized phosphorus from the high-temperature gas as yellow phosphorus or a phosphorus compound A facility for recovering phosphorus from waste characterized by having a phosphorus recovery means.

Further, the present invention provides a step of forming a granular material containing a phosphorus or a waste containing a phosphorus compound and a carbon source, wherein the granular material contains phosphorus which has been vaporized by heating in a reducing atmosphere. A method for recovering phosphorus from waste, comprising a step of generating a high-temperature gas and a step of recovering the vaporized phosphorus from the high-temperature gas as yellow phosphorus or a phosphorus compound.

In the present invention, the recovery of yellow phosphorus or phosphoric acid from the high-temperature gas can be performed, for example, by using a condenser that converts the vaporized phosphorus into yellow phosphorus by condensing the high-temperature gas. Further, the recovery of yellow phosphorus or a phosphorus compound from a high-temperature gas includes a phosphorus pentoxide generating means for mixing a high-temperature gas and a gas containing oxygen to convert phosphorus vaporized to phosphorus pentoxide, and a high-temperature gas and oxygen A phosphoric acid generating means for producing a phosphoric acid aqueous solution by dissolving phosphorus pentoxide contained in the mixed gas in water by bringing a mixed gas obtained by mixing the gas with water into contact with water can be used.

In the present invention, the particulate matter can be formed by using a mixture of the waste, the carbon source, and a by-product generated by the recovery of the phosphorus. When the step of recovering phosphorus is carried out by condensing a high-temperature gas, the by-products include sludge generated with the condensation of the high-temperature gas. In this case, the granular material may be formed after oxidizing the sludge. When the step of recovering phosphorus from the high-temperature gas is performed by generating a phosphoric acid aqueous solution, the by-product may include the phosphoric acid aqueous solution.

In the present invention, usually, after the vaporized phosphorus is recovered as yellow phosphorus or a phosphorus compound, the exhaust gas is washed by bringing the exhaust gas generated with the recovery of phosphorus into contact with water. The water used to clean this exhaust gas also
The by-products described above can be used to form the particles.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings.

FIG. 1 schematically shows a facility for recovering phosphorus from waste according to a first embodiment of the present invention. The recovery equipment shown in FIG. 1 includes a kneader 30, a granulator 31, a dryer 32, a closed electric resistance melting furnace 1, a dust remover 10, a condenser 20, a phosphorus storage tank 21, a combustion tower 22, an absorption tower 12, It mainly comprises a phosphoric acid storage tank 13, a mist collector 14, and a gas cleaning tower 15. In FIG. 1, a condenser 20, a phosphorus storage tank 21,
The combustion tower 22, the absorption tower 12, and the phosphoric acid storage tank 13 constitute phosphorus recovery means.

In the kneader 30, waste containing phosphorus or a phosphorus compound such as sewage sludge incineration ash, a carbon source such as coke powder, and, if necessary, a liquid component necessary for granulation described later, etc. Are supplied and these are mixed. The waste containing phosphorus or the phosphorus compound preferably has a particle size of 0.1 mm or less like incinerated ash. When the particle size of the waste is sufficiently small, the waste can be uniformly mixed with a carbon source and the like, and the phosphorus compound described below can be efficiently reduced. When the particle size of the waste is larger than 0.5 mm, it is preferable to pulverize the waste into fine particles having a particle size of 0.5 mm or less, and then mix the fine particle with a carbon source or the like.

The mixture obtained by mixing in the kneading machine 30 is supplied to a granulator 31 such as a briquetting machine or a dish granulator. In the granulator 31, the mixture is granulated to obtain granules having a desired shape. The granulation by the granulator 31 is preferably performed under such conditions that granules having sufficiently high compressive strength are formed. For example,
When the granules are formed into tablets of 24 mm × 16 mm almond shape, the compressive strength is preferably 30 kg or more. When the compressive strength was less than 30 kg, the breaking ratio due to the drop was high (the breaking ratio in a concrete floor drop test from a height of 2 m was 20% or more).

When the moisture content of the granular material formed by the granulator 31 is high, a large amount of moisture evaporates during the melting process in the melting furnace 1 described later, and the power loss may be excessive. . In such a case, it is preferable to dry the granular material formed by the granulator 31 in the dryer 32.

The melting furnace 1 is a heating furnace that heats a granular material formed by the granulator 31 in a reducing atmosphere to generate a high-temperature gas containing vaporized phosphorus. The melting furnace 1 has a closed structure, and a layer made of a carbon-based refractory is formed on the inner wall thereof. An electrode 2 made of, for example, graphite is provided on the upper part of the melting furnace 1 so as to be movable in a vertical direction by an electrode lifting device 3. A power supply 4 is connected to the electrodes 2 so that a desired voltage can be applied to each electrode.

In FIG. 1, reference numerals 40 to 42 denote a granular material layer, a molten slag layer, and a molten metal layer formed by the granulator 31, respectively. Melting furnace 1 in operation
Inside, the immersion depth of the electrode 2 in the molten slag layer 41 is controlled by the electrode lifting / lowering device 3, and a predetermined voltage is applied from the power supply 4. At this time, the temperature of the molten slag layer 41 increases because the molten slag layer 41 functions as an electric resistor. The granular material in the granular material layer 40 is, for example, 130
It is heated by the heat from the molten slag layer 41 maintained at 0 ° C. to 1600 ° C. and gradually melts into the molten slag layer 41.

As described above, the granular material formed by the granulator 31 contains incinerated ash and coke powder. That is, the phosphorus compound contained in the incineration ash and the carbon source required for its reduction are close to each other. This state is maintained until the granular material is melted or broken. Therefore, according to the present embodiment, the contact probability between the phosphorus compound contained in the incineration ash and the carbon supplied from the coke powder is increased, and the reduction of the phosphorus compound is performed in a short time. Phosphorus gas can be generated.

The granular material formed by the granulator 31 is supplied into the melting furnace 1 from the upper part of the melting furnace 1 as described above.
The particulate matter layer 40 floating on the molten slag layer 41 is formed. The granular material in the granular material layer 40 is heated by the heat supplied from the molten slag layer 41. The reaction between the phosphorus compound and carbon starts to proceed at 1000 ° C. or higher, and the reaction rate rapidly increases at 1200 ° C. or higher. Therefore, almost all of the phosphorus or the phosphorus compound contained in the granular material 40 can be vaporized before the granular material in the granular material layer 40 reaches the molten slag layer 41. Therefore, it is possible to prevent the phosphorus compound from being mixed into the molten slag layer 41 and the molten metal layer 42, thereby preventing the carbonaceous furnace wall from being eroded by the reaction with the phosphorus compound.

The granular material formed by the granulator 31 generates a melt and a high-temperature exhaust gas by such a heat treatment. This melt is separated in the melting furnace 1 into a molten slag layer 41 and a molten metal layer 42 containing metallic iron as a main component. The molten metal constituting the molten metal layer 42 is supplied to the metal outlet 6
The molten slag constituting the molten slag layer 41 is discharged out of the furnace from the slag discharge port 5.

The high-temperature exhaust gas generated by the heat treatment contains phosphorus gas, carbon monoxide gas, water vapor, and the like. This exhaust gas is exhausted out of the furnace from the gas outlet 7,
It is sent to a dust remover 10 such as a cotrel dust collector or a cyclone dust collector.

As described above, conventionally, incineration ash soars in the melting furnace 1 and a large amount of dust is exhausted from the melting furnace 1 together with the exhaust gas. On the other hand, according to the present embodiment, since the incinerated ash is granulated, scattering of the incinerated ash in the melting furnace 1 is suppressed. Therefore, according to the present embodiment, it is possible to suppress dust from being mixed into the exhaust gas.

In the dust remover 10, dust contained in the exhaust gas is removed from the exhaust gas by, for example, electric dust collection or cyclone dust collection. As described above, the dust concentration in the exhaust gas exhausted from the melting furnace 1 is reduced as compared with the related art. Therefore, the exhaust gas from which dust has been removed by the dust remover 10 has a much lower dust concentration than the conventional exhaust gas.

The dust remover 10 is not particularly limited as long as it has sufficient heat resistance to the above-mentioned exhaust gas. Further, it is preferable that the dust remover 10 is provided with a heating means for heating a portion in contact with the exhaust gas to 280 ° C. or more, which is the boiling point of yellow phosphorus. When such a heating means is provided, it is possible to prevent the phosphorus gas from being condensed and liquefied or solidified in the dust remover 10.

The exhaust gas from which dust has been removed by the dust remover 10 is supplied to the condenser 20. Water is sprayed in the condenser 20, and the exhaust gas supplied to the condenser 20 is cooled by the sprayed water. As a result, the phosphorus gas contained in the exhaust gas is condensed into a liquid, and is discharged from the bottom of the condenser 20.

The liquid phosphorus discharged from the condenser 20 is sent to a phosphorus storage tank 21. The liquid yellow phosphorus in the phosphorus storage tank 21 is then sprayed into the combustion tower 22 by a pump. At this time, an oxidizing gas such as air is simultaneously introduced into the combustion tower 22 to generate phosphorus pentoxide.

The exhaust gas containing phosphorus pentoxide is supplied to the absorption tower 12. In the absorption tower 12, a phosphoric acid aqueous solution is circulated. The exhaust gas supplied to the absorption tower 12 comes into contact with a phosphoric acid aqueous solution sprayed from above in the absorption tower 12, and as a result, phosphorus pentoxide contained in the exhaust gas is absorbed by the phosphoric acid aqueous solution and converted into phosphoric acid.

In the absorption tower 12, the supply amount of water is controlled so that the circulated phosphoric acid aqueous solution has a predetermined concentration. The phosphoric acid thus generated is converted into an aqueous phosphoric acid solution in the absorption tower 12.
And is stored in the phosphoric acid storage tank 13.

On the other hand, the exhaust gas from which phosphorus pentoxide has been removed is sent to a mist collector 14, where the phosphate mist is removed. The exhaust gas from which the phosphoric acid mist has been removed is further sent to the gas cleaning tower 15. In the gas cleaning tower 15, exhaust gas is purified by spraying water. After cleaning as described above, the exhaust gas is exhausted from the gas cleaning tower 15 to the atmosphere.

As described above, according to this method, the incinerated ash is supplied to the melting furnace 1 after being granulated, so that the incorporation of dust into the exhaust gas exhausted from the melting furnace 1 is suppressed. Therefore, the dust concentration in the exhaust gas supplied to the condenser 20 is reduced. Therefore, the phosphoric acid aqueous solution produced by the above method hardly contains dust. That is, according to the above method, it is possible to recover phosphorus or phosphoric acid with high purity from waste containing phosphorus or a phosphorus compound. Also, since the exhaust gas contains almost no dust,
According to the above method, the amount of sludge in the condenser 20 or the like can be reduced.

As described above, according to the above method, the amount of sludge can be reduced, but it is still difficult to completely prevent the generation of sludge. In such a case, it is preferable to supply sludge and the like together with the incineration ash and coke powder to the kneading machine 30 and collect the phosphorus mixed in the sludge and the like by the above-described method. The reason will be described below.

The liquid phosphorus generated by the condensation of the phosphorus gas in the condenser 20 floats in circulating hot water in a particulate form. These particulate liquid phosphorus eventually aggregate and settle at the bottom of the condenser 20. On the other hand, dust supplied to the condenser 20 together with the exhaust gas and trapped in the circulating hot water also settles at the bottom of the condenser 20. Since the dust has a lower specific gravity than liquid phosphorus, the dust settled at the bottom of the condenser 20 forms a sludge layer on the liquid phosphorus layer.

However, the sludge layer does not consist only of dust, but contains yellow phosphorus and phosphoric acid in high concentrations. Therefore, treatment such as oxidation treatment of yellow phosphorus in the sludge is separately required. Therefore, by supplying sludge together with incineration ash and coke powder to the kneading machine 30, and recovering the phosphorus content mixed into the sludge or the like by the above-described method, the sludge can be treated at low cost. Can be improved.

When recovering phosphorus from sludge in the condenser 20, the sludge is used as a mixture with circulating hot water in the condenser 2
It is preferable to discharge from zero. The sludge contains circulating warm water in which phosphoric acid is dissolved together with yellow phosphorus as described above. Exhaust gas supplied to the condenser 20 contains phosphorus pentoxide by partly participating in phosphorus gas. The phosphorus pentoxide is generated by reacting the phosphorus gas generated in the melting furnace 1 with oxygen that has entered the passage in the process of reaching the condenser 20. Therefore, the circulating hot water in the condenser 20 contains phosphoric acid generated by absorbing phosphorus pentoxide in the exhaust gas.
That is, the circulating hot water in the condenser 20 also contains a relatively high concentration of phosphorus, similar to the sludge. Therefore, by discharging the sludge from the condenser 20 as a mixed liquid with the circulating hot water, it is possible to recover more phosphorus.

The mixed liquid of the sludge and the circulating hot water discharged from the condenser 20 in this manner is usually diffused before being supplied to the kneader 30 in order to convert the yellow phosphorus in the mixed liquid into phosphoric acid. An oxidation treatment using air is performed in the tank. In addition, this oxidation treatment may be performed by mixing an oxidizing agent such as aqueous hydrogen peroxide or sodium hypochlorite into the mixed solution.

The sludge containing phosphorus is generated not only in the condenser 20 but also in the absorption tower 12. Sludge generated in the absorption tower 12 can be recovered by a method similar to that described for the condenser 20.

In the gas cleaning tower 15, phosphoric acid and dust mixed in the exhaust gas are absorbed by the cleaning water. Therefore, sludge is generated at the bottom of the gas cleaning tower 15 and the cleaning water contains phosphoric acid. Therefore, sludge generated in the gas cleaning tower 15 can be recovered by the same method as described for the condenser 20.

In the first embodiment described above,
Although the closed electric resistance type melting furnace 1 is used as the heating furnace, an externally heated closed kiln furnace or the like may be used. Further, in the first embodiment, the liquid yellow phosphorus generated in the condenser 20 is converted into phosphorus pentoxide in the combustion tower 22 and further recovered as an aqueous phosphoric acid solution in the absorption tower 12. Can be used as it is as an industrial raw material. In this case, the phosphorus compound in the waste can be recovered from the condenser 20 as yellow phosphorus.

Next, a second embodiment of the present invention will be described with reference to FIG.
An embodiment will be described. In FIG. 2, members common to those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

FIG. 2 is a view schematically showing a facility for recovering phosphorus from waste according to a second embodiment of the present invention. The recovery equipment shown in FIG. 2 includes a kneader 30, a granulator 31, a dryer 32, a closed electric resistance type melting furnace 1, a dust remover 10, a combustion chamber 11, an absorption tower 12, a phosphoric acid storage tank 13, a mist collector. 14,
And a gas cleaning tower 15. Note that FIG.
, The combustion chamber 11, the absorption tower 12, and the phosphoric acid storage tank 13
Constitutes a phosphorus recovery means.

According to the second embodiment, the recovery of phosphorus is performed, for example, by the following method. First, the dust remover 10
Is used to remove dust from the exhaust gas by the same method as described in the first embodiment.

The exhaust gas from which dust has been removed by the dust remover 10 is then sent to the combustion chamber 11. An oxidizing gas such as air or oxygen is introduced into the combustion chamber 11 to burn carbon monoxide gas or the like contained in exhaust gas. At the same time, the phosphorus gas contained in the exhaust gas is also burned to generate phosphorus pentoxide.

The exhaust gas containing phosphorus pentoxide is supplied to the absorption tower 12. In the absorption tower 12, phosphorus pentoxide contained in the exhaust gas is recovered as a phosphoric acid aqueous solution in the same manner as described in the first embodiment. Exhaust gas from which phosphorus pentoxide has been removed is also sent to the mist collector 14 and the gas cleaning tower 15 in the same manner as described in the first embodiment, and then exhausted to the atmosphere. .

According to the above-described second embodiment, the same effects as those described in the first embodiment can be obtained. Also in the second embodiment, the waste liquid containing the sludge and the circulating phosphoric acid aqueous solution is supplied to the kneader 30 together with the incineration ash and the coke powder, and the phosphorus mixed in the sludge or the like is recovered by the above-described method. Thus, sludge and the like can be treated at low cost, and the recovery rate of phosphorus can be improved.

Further, in the second embodiment, unlike the first embodiment, the phosphorus gas contained in the exhaust gas exhausted from the melting furnace 1 is converted into phosphorus pentoxide without passing through yellow phosphorus. Therefore, according to the second embodiment, it is possible to recover the phosphorus compound contained in the waste as a phosphoric acid aqueous solution with equipment having a more simplified configuration than in the first embodiment.

[0052]

Embodiments of the present invention will be described below.

(Example) Using the phosphorus recovery plant shown in FIG. 1, yellow phosphorus was recovered from sewage sludge incineration ash by the following method. That is, first, a total of 50 liters of sludge and circulating hot water generated in the condenser 20 by operating the phosphorus recovery plant shown in FIG. 1 were collected. These mixtures were aerated with air until no more white smoke was generated to convert the yellow phosphorus contained in the sludge to phosphoric acid. The liquid after the aeration was in a state in which dust was suspended, and the concentration of phosphoric acid (P ₂ O ₅ ) was 24% by weight.

Next, the sewage sludge incineration ash, the coke powder, and the phosphoric acid aqueous solution obtained by the above-described method were mixed by the mixer 30. The amounts of sewage sludge incineration ash, coke powder, and phosphoric acid aqueous solution supplied to the mixer 30 were 1250 k, respectively.
g, 188 kg, and 63 kg.

Using a mixture obtained by mixing these with a mixer 30, a briquetting machine 31 is used.
Thus, briquettes having a thickness of 5.0 mm and an apparent density of 1.7 g / cm ³ were formed. In addition, briquetting machine 3
1 was equipped with a 9 × 6 mm almond-shaped molding roll, the roll supporting pressure was 60 kg / cm ² , the roll interval was 0.5 mm, and the roll rotation speed was 50 rpm.

The briquettes obtained in this way were
It was supplied to the melting furnace 1 at a rate of 00 kg / h. The melting furnace 1 is a closed electric resistance type melting furnace having an inner diameter of 700 mm and an output of 500 kW. The briquette melting process was performed so that the temperature of the molten slag layer 41 was maintained at 1400 ° C. Further, the slag was intermittently discharged from the melting furnace 1.

The exhaust gas generated in the melting furnace 1 was supplied to a condenser 20 after dust was removed by a cyclone type dust collector 10. In the condenser 20, phosphorus gas was condensed by spraying hot water of 60 ° C. on the exhaust gas.

The exhaust gas discharged from the condenser 20 was supplied to a combustion tower (not shown) and was burned using air. After that, this exhaust gas is washed by a gas washing tower (not shown),
Exhausted into the atmosphere.

Operating for 15 hours under the above conditions,
1.25 t of sewage sludge incineration ash was treated. After the charging of the briquettes into the melting furnace 1 was stopped, the inside of the condenser 20 was heated to 60 ° C.
, And allowed to stand for 24 hours to settle the particles floating in the circulating warm water. As a result, about 72
kg of liquid yellow phosphorus could be obtained.

A sludge layer containing dust and yellow phosphorus was formed on the yellow phosphorus layer deposited on the bottom of the condenser 20. When the sludge was discharged from the condenser 20 and its weight was measured, it was about 7 kg. Analysis of the composition of this sludge revealed that it contained 10% by weight of yellow phosphorus. The amount of dust collected by the dust collector 10 is 1
It was 2 kg.

The compositions of the sewage sludge incineration ash tested and the composition of the yellow phosphorus recovered from the condenser 20 and filtered are shown in Tables 1 and 2 below, respectively.

[0062]

[Table 1]

[0063]

[Table 2]

As shown in Table 2 above, the purity of the yellow phosphorus obtained by the above-mentioned method was 99.95%, and it was confirmed that the quality was sufficient to be used as an industrial raw material.

As described above, according to the method of the present embodiment, about 50 liters of waste liquid containing sludge was used for the recovery of phosphorus from 1.25 ton sewage sludge incineration ash. That is, about 7 kg of phosphorus (P
It was possible to supply 15kg equivalent) in the recovery process ₂ O ₅ basis.

(Comparative Example) Sewage sludge incineration ash and coke powder were charged into the melting furnace 1 from separate supply ports, respectively, without forming briquettes. Yellow phosphorus was recovered from the sludge incineration ash. As a result, about 60 kg of yellow phosphorus and about 12 kg of sludge were recovered from the bottom of the condenser 20. The sludge contained 12% by weight of yellow phosphorus.

Next, the components of the recovered yellow phosphorus were analyzed. The results are shown in Table 3 below.

[0068]

[Table 3]

As shown in Table 3 above, the purity of the recovered yellow phosphorus was 99.90%, which was a quality usable as an industrial raw material, but was lower than that in the above Examples. Further, a large amount of suspended dust was present in the recovered yellow phosphorus, and a long time was required for the filtration treatment.

[0070]

As described above, in the present invention, the waste containing the phosphorus compound is granulated together with the carbon source prior to the melting treatment. Therefore, the contact probability between the phosphorus compound contained in the waste and carbon supplied from the carbon source during the melting treatment can be increased. Further, at the time of granulation of the waste and the carbon source, by mixing sludge or the like generated with the recovery of phosphorus, phosphorus contained in the sludge or the like can be recovered. That is,
It is possible to reduce the cost spent for treating sludge and the like generated with the recovery of phosphorus.

Therefore, according to the present invention, there is provided an apparatus and method for recovering phosphorus from waste, which makes it possible to increase the probability of contact between the phosphorus compound contained in the waste and carbon supplied from the carbon source. You. Further, according to the present invention, there is provided an apparatus and a method for recovering phosphorus from waste, which can reduce the cost spent for treating sludge and the like caused by the recovery of phosphorus.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a facility for recovering phosphorus from waste according to a first embodiment of the present invention.

FIG. 2 is a diagram schematically showing a facility for recovering phosphorus from waste according to a second embodiment of the present invention.

[Explanation of symbols]

1 ... melting furnace; 2 ... electrode; 3 ... electrode elevating device;
4 power supply 5 slag discharge port 6 metal discharge port 7 gas discharge port 10 dust remover 11 combustion chamber 12 absorption tower 13 phosphoric acid storage tank 14 mist collector 15 gas cleaning Towers; 20
... condenser 21 ... phosphorus storage tank; 22 ... combustion tower; 30 ... kneader 31 ... granulator; 32 ... dryer; 40 ... mixture 41 ... molten slag; 42 ... molten metal

 ──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Keisuke Nakahara 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Hiroshi Yamamoto 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Sun Nippon Kokan Co., Ltd. (72) Inventor Takuya Shinagawa 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Inventor Kiyoyoshi Tabei 9-11-1, Kameido, Koto-ku, Tokyo Nippon Kagaku Industry Co., Ltd. (72) Inventor Toshiro Kuwayama 9-11-1, Kameido, Koto-ku, Tokyo Nippon Kagaku Kogyo Co., Ltd. F-term (reference) 3K070 DA01 DA06 DA07 DA29 DA37 DA42 DA44 DA45 DA47 DA52 4D004 AA36 BA10 CA14 CA15 CA24 CA27 CA32 CA37 CA41 CA42 CA50 CB04 CB32 CB50 CC02 CC11 DA03 DA06

Claims (11)

[Claims] 1. Granulation means for forming a granular material containing phosphorus or a waste containing a phosphorus compound and a carbon source, wherein said granular material is supplied from said granulating means, and said granular material is reduced under a reducing atmosphere. A waste furnace comprising: a heating furnace that generates a high-temperature gas containing vaporized phosphorus by heating; and a phosphorus recovery unit that recovers the vaporized phosphorus from the high-temperature gas as yellow phosphorus or a phosphorus compound. Equipment to recover phosphorus. 2. The phosphorus recovery device according to claim 1, wherein said phosphorus recovery means includes a condenser for converting said vaporized phosphorus to yellow phosphorus by condensing said high-temperature gas. Equipment to collect. 3. The phosphorus recovery unit includes a phosphorus pentoxide generating unit that mixes the high-temperature gas and a gas containing oxygen to convert the vaporized phosphorus to phosphorus pentoxide, and includes the high-temperature gas and oxygen. A phosphoric acid generating means for producing a phosphoric acid aqueous solution by dissolving phosphorus pentoxide contained in the mixed gas in the water by contacting a mixed gas formed by mixing the gas with water. Item 2. An apparatus for recovering phosphorus from the waste according to item 1. 4. A step of forming a particulate matter containing a phosphorus or a waste containing a phosphorus compound and a carbon source, wherein the particulate matter is heated in a reducing atmosphere to generate a high-temperature gas containing phosphorus vaporized. And recovering the vaporized phosphorus from the high-temperature gas as yellow phosphorus or a phosphorus compound. 5. The step of recovering phosphorus from the hot gas,
5. The method for recovering phosphorus from waste according to claim 4, comprising converting the vaporized phosphorus to yellow phosphorus by condensing the hot gas. 6. The step of recovering phosphorus from the high-temperature gas includes: mixing the high-temperature gas and a gas containing oxygen to convert the vaporized phosphorus to phosphorus pentoxide; 5. A phosphoric acid aqueous solution is produced by dissolving phosphorus pentoxide contained in the mixed gas in the water by contacting a mixed gas obtained by mixing a gas containing the same with water. The method for recovering phosphorus from the waste according to the above. 7. The step of forming the particles includes forming the particulate matter using a mixture of the waste, the carbon source, and a by-product generated in the recovery of the phosphorus. A method for recovering phosphorus from the waste according to any one of claims 4 to 6. 8. The step of recovering phosphorus from the hot gas,
8. The waste of claim 7, including converting the vaporized phosphorus to yellow phosphorus by condensing the hot gas, wherein the by-products include sludge produced with the condensation of the hot gas. Of recovering phosphorus from materials. 9. The step of recovering phosphorus from the hot gas,
The method according to claim 1, further comprising: converting the vaporized phosphorus to yellow phosphorus by condensing the hot gas; and wherein the by-product includes an oxidized sludge generated by condensing the hot gas. 8. A method for recovering phosphorus from waste according to 7. 10. The step of recovering phosphorus from the high-temperature gas includes mixing the high-temperature gas and a gas containing oxygen to convert the vaporized phosphorus to phosphorus pentoxide, and converting the high-temperature gas and oxygen. And dissolving the phosphorus pentoxide contained in the mixed gas in the water by contacting the mixed gas obtained by mixing the mixed gas with the water to generate a phosphoric acid aqueous solution. The method for recovering phosphorus from waste according to claim 7, comprising: 11. The method according to claim 1, further comprising, after the step of recovering the vaporized phosphorus as yellow phosphorus or phosphoric acid, a step of washing the exhaust gas by contacting water with an exhaust gas generated during the recovery of the vaporized phosphorus. The method for recovering phosphorus from waste according to claim 7, wherein the by-product includes water used for cleaning the exhaust gas.