JP2022017907A - Waste melting method, waste molten slag powder, and method of producing the same - Google Patents

Abstract

To provide a waste melting method capable of enhancing work efficiency.SOLUTION: The method of melting waste by melting the waste and an auxiliary material containing one or both of a magnesium component and an iron component in a coke bed type melting furnace, comprises a process of heating the waste and the auxiliary material up to a temperature of 1600°C or higher to melt the same in a melting furnace, a process of discharging molten slag from the melting furnace, and a process of introducing molten slag into a water granulation tank to granulate the same with water, with the molten slag having a viscosity of not higher than 5 Pa s upon contacting the cooling water present in the water granulation tank.SELECTED DRAWING: None

Description

The present disclosure relates to a waste melting treatment method, a waste melting slag powder, and a method for producing the same.

As a waste treatment method, a waste melting treatment method for melting waste using a melting furnace is known. As a type of melting furnace used in such a treatment method, various types such as a shaft furnace type, a kiln type, and a fluidized bed type are known.

For example, Patent Document 1 proposes to reduce the viscosity of slag during a melting process by setting the basicity of the slag in the range of 0.5 to 1.0. Specifically, incinerator is melted at 1100 to 1500 ° C. to form slag in a swirling melting furnace, and the slag is formed at a temperature of about 1500 ° C. (preferably at a temperature of about 1400 ° C., more preferably at a temperature of about 1300 ° C.). It has been proposed to reduce the viscosity to about 2.0 Pa · s or less.

In Patent Document 2, the viscosity of the molten slag at the slag opening is 1.8 Pa · s in order to suppress the blockage of the molten slag when the slag is discharged from the slag opening of the melting furnace and to facilitate the discharge of the molten slag. It is proposed to be less than.

Japanese Patent Application Laid-Open No. 2003-212615 Japanese Patent No. 6339725

The molten slag discharged from the melting furnace is cooled in a granulation tank and then transported and disposed of, or used for other purposes for effective utilization. For example, it is powdered and used as a raw material for roadbed materials, refractories, cement, fertilizers, and the like. However, since the slag after granulation contains needle-shaped slag, it is difficult to remove the needle-shaped slag clinging to the worker's gloves when handling the slag after granulation, and the shape is even longer. In the case of needle-shaped slag, it is necessary to replace or inspect the gloves by penetrating the gloves of the operator during handling, and there is a concern that the work efficiency when using the molten slag will be reduced. Therefore, the present inventors have investigated various factors for the formation of needle-shaped slag, and found that the conditions for hydrolyzing the molten slag are greatly involved in the formation of needle-shaped slag. Then, it was found that it is effective to suppress the formation of needle-shaped slag by adjusting the viscosity of the molten slag when it is introduced into the granulation tank, not the viscosity of the molten slag in the melting furnace and at the outlet.

Therefore, the present disclosure provides a waste melting treatment method capable of improving work efficiency. Further, the present invention provides a waste molten slag powder capable of improving work efficiency and a method for producing the same.

The present disclosure is, in one aspect, a waste melting treatment method in which a waste and an auxiliary material containing one or both of a magnesium component and an iron component are melted in a coke bed type melting furnace, and the waste and the auxiliary material are used. It has a step of heating the molten slag to 1600 ° C. or higher in a melting furnace to melt it, a step of discharging the molten slag from the melting furnace, and a step of introducing the molten slag into a granulation tank and granulating it. Provided is a waste melting treatment method in which the viscosity of the molten slag when in contact with the cooling water in the tank is 5 Pa · s or less.

In the above waste treatment method, since the auxiliary material containing one or both of the waste and the magnesium component and the iron component is heated to 1600 ° C. or higher in a coke bed type melting furnace, the waste is sufficiently melted. Can be done. The viscosity of the molten slag when it comes into contact with the cooling water in the granulation tank is set to 5 Pa · s or less. Therefore, it is considered that the stringing phenomenon of the molten slag when introduced into the granulation tank is suppressed, and the formation of needle-shaped slag can be suppressed. Therefore, it is possible to improve the handleability of the slag after water crushing and improve the work efficiency.

The auxiliary material may contain both a magnesium component and an iron component, and the total content of FeO and MgO in the molten slag may be 4% by mass or more. This makes it possible to further suppress the formation of needle-shaped slag. Therefore, the handleability of the slag after water crushing can be further improved, and the work efficiency can be further improved.

The waste melting treatment method may include a step of measuring the temperature of the molten slag when it comes into contact with the cooling water in the granulation tank. By measuring this temperature, the viscosity of the molten slag when it is introduced into the granulation tank can be stably controlled.

The waste melting treatment method includes a step of obtaining waste molten slag powder having a needle-shaped slag content of 0.5% by mass or less from the granulated slag obtained by hydrolyzing in the granulation tank. May be good. As a result, phenomena such as clinging to gloves are suppressed, and waste molten slag powder having sufficiently excellent work efficiency can be obtained. Such waste molten slag powder can be suitably used for various uses.

The present disclosure provides, in one aspect, a waste molten slag powder having a needle-like slag content of 0.5% by mass or less. Here, the waste molten slag powder in the present disclosure means a powder obtained by crushing slag obtained in a waste melting furnace. The needle-shaped slag in the present disclosure means a needle-shaped slag having a length of a line segment connecting both ends of 5 mm or more. The thickness of at least one of both ends of the needle-shaped slag may be, for example, 0.37 mm or less, or may be 0.3 mm or less. When the end face of the end face is circular, the thickness is equal to the outer diameter of the end face. On the other hand, when the end face is not circular, the length of the maximum line segment among the line segments connecting two different points on the outer edge of the end face is defined as the thickness at the end. Since the content of such sharp needle-shaped slag is sufficiently reduced in the waste molten slag powder of the present disclosure, phenomena such as clinging to gloves can be suppressed, and work efficiency can be improved.

The total content of FeO and MgO in the waste molten slag powder may be 4% by mass or more. As a result, the proportion of particles having a needle shape that is not classified as needle-shaped slag can be reduced, and the work efficiency when using the waste molten slag powder can be further improved.

In one aspect, the present disclosure comprises a step of heating a waste and an auxiliary material containing one or both of a magnesium component and an iron component to a temperature of 1600 ° C. or higher in a coke bed type melting furnace to melt the waste. It has a step of discharging molten slag from water, a step of introducing the molten slag into a granulation tank and granulating it to obtain granulated slag, and a step of obtaining waste molten slag powder from the granulated slag. Provided is a method for producing a waste molten slag powder, which has a viscosity of molten slag of 5 Pa · s or less when it comes into contact with cooling water in a crushing tank.

In the above manufacturing method, since the auxiliary material containing one or both of the waste and the magnesium component and the iron component is heated to 1600 ° C. or higher in a coke bed type melting furnace, the waste can be sufficiently melted. .. The viscosity of the molten slag when introduced into the granulation tank is set to 5 Pa · s or less. Therefore, the stringing phenomenon of the molten slag when introduced into the granulation tank is suppressed, and the formation of needle-shaped slag in the granulation slag can be suppressed. Therefore, it is possible to produce the waste molten slag powder that can improve the work efficiency when using the waste molten slag powder.

The content of needle-shaped slag in the waste molten slag powder obtained by the above production method may be 0.5% by mass or less. This makes it possible to further improve the working efficiency of the waste molten slag powder. Such waste molten slag powder can be suitably used for various uses.

According to the present disclosure, it is possible to provide a waste melting treatment method capable of improving work efficiency. Further, it is possible to provide a waste molten slag powder capable of improving work efficiency and a method for producing the same.

FIG. 1 is a diagram schematically showing an example of a coke bed type melting furnace and a waste melting treatment facility equipped with the coke bed type melting furnace. FIG. 2 is a diagram schematically showing an example of a water crushing tank for performing a step of crushing molten slag. FIG. 3 is a photograph of a slag having a length of 10 mm or more. FIG. 4 is a photograph of a slag having a length of 5 mm or more and less than 10 mm. FIG. 5 is a photograph of a slag having a length of less than 5 mm. FIG. 6 is a photograph of the waste molten slag powder of Comparative Example 1. FIG. 7 is a graph showing the relationship between the total content of FeO and MgO of the molten slag and the viscosity of the molten slag immediately before contacting with the cooling water. FIG. 8 is a photograph of waste molten slag powder distributed in the market.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings as the case may be. However, the following embodiments are examples for explaining the present disclosure, and are not intended to limit the present disclosure to the following contents.

The waste melting treatment method according to one embodiment includes a charging step of charging waste, carbonaceous material and auxiliary materials into a coke bed type melting furnace, and heating the waste and auxiliary materials to 1600 ° C. or higher. It has a melting step of melting, a slag step of discharging molten slag from the outlet of a melting furnace, and a granulation step of introducing the molten slag into a granulation tank to obtain granulated slag. This waste melting treatment method can be performed using, for example, the waste melting treatment equipment 100 shown in FIG. The waste melting treatment method using the waste melting treatment equipment 100 will be described below.

The waste melting treatment facility 100 of FIG. 1 includes a coke bed type melting furnace 40 and a charging device 50 provided above the melting furnace 40. The melting furnace 40 has a shaft portion 42, a morning glory portion 44 provided at the lower end of the shaft portion 42, and a furnace bottom portion 46 provided at the lower portion of the morning glory portion 44. The upper tuyere 45 for the pyrolysis zone and the lower tuyere 47 for the combustion melting zone are provided from the shaft portion 42 to the furnace bottom portion 46 in this order from the top. The upper tuyere 45 and the lower tuyere 47 may be provided in a plurality of stages, respectively.

Waste, charcoal material and auxiliary materials are charged into the melting furnace 40 by the charging device 50. Wastes include general waste, industrial waste, treated products such as incineration ash obtained by treating them with drying, incineration, crushing, etc., and earth and sand dug up again after landfilling them once. Examples include landfill waste including minutes.

The auxiliary material may contain one or both of the magnesium component and the iron component. Examples of the magnesium component include magnesium carbonate, magnesium oxide compounds, MgO brick scraps and the like. Examples of the iron component include iron oxide. Examples of the auxiliary material containing magnesium carbonate include dolomite, dolomite, ballintnite, neskehonite, lanceholtite and the like. Examples of the auxiliary material containing the magnesium oxide-based compound include magnesia, pericrace, kudokanran stone, and jamon stone. Iron ore can be mentioned as an auxiliary material containing iron oxide. As an auxiliary material, steelmaking slag containing both a magnesium component and an iron component (converter system slag and electric furnace system slag) may be used. By using such an auxiliary material, the waste 48 can be sufficiently melted inside the melting furnace 40. Further, the auxiliary material may contain limestone.

As the charcoal material, coal, coke, briquette or the like can be used. Since incinerator ash is difficult to dissolve, needle-shaped slag is usually likely to be formed. However, according to the waste melting treatment method of the present embodiment, needle-shaped slag can be sufficiently reduced even if the waste contains incinerator ash.

From the viewpoint of further suppressing the formation of needle-shaped slag, the total content of MgO and FeO in the molten slag discharged from the slag opening 49 is preferably 4% by mass or more. It is more preferably adjusted to be 6% by mass or more, and more preferably 8% by mass or more. The content of MgO in the molten slag may be 1% by mass or more. The content of FeO in the molten slag may be 1% by mass or more.

The total content of MgO and FeO in the molten slag discharged from the slag opening 49 is less than 20% by mass from the viewpoint of suppressing an increase in the amount of auxiliary materials charged and the amount of molten slag discharged. It may be present, and may be less than 15% by mass. From the same viewpoint, the content of MgO in the molten slag discharged from the slag opening 49 may be less than 12% by mass and may be less than 10% by mass. From the same viewpoint, the content of FeO in the molten slag discharged from the slag opening 49 may be less than 15% by mass and may be less than 12% by mass.

The auxiliary material may contain components other than MgO and FeO. For example, it may contain at least one selected from the group consisting of CaO, SiO ₂ , Al ₂ O ₃ and MnO. In this case, the basicity of the molten slag (CaO / SiO ₂ ) may be adjusted to 0.5 to 1.2.

Waste, auxiliary materials and charcoal materials are charged from the charging device 50, while oxygen or oxygen-enriched air is supplied from the lower tuyere 47 and as combustion support gas from the upper tuyere 45. Air is supplied. The charcoal material charged into the melting furnace 40 is burned by oxygen or oxygen-enriched air supplied from the lower tuyere 47 and functions as a heat source. The waste 48 charged into the melting furnace 40 is heated by the combustion of the carbonaceous material to become a pyrolysis residue 43. The pyrolysis residue 43 is mainly burned by the air supplied from the upper tuyere 45.

The pyrolysis gas generated in the melting furnace 40 rises in the shaft portion 42 and is introduced into the combustion chamber from the exhaust gas pipe 52 connected to the lower part of the charging device 50. After the combustion exhaust gas is burned as combustible gas, waste heat is recovered by a boiler. After that, the exhaust gas is discharged from the chimney through the dust collector and the catalytic reaction tower after the temperature is adjusted by the temperature reducing tower.

Inside the melting furnace 40, a temperature gradient is generated by combustion of carbonaceous material or the like. Specifically, the melting furnace 40 has a drying / pre-tropical zone 40a, a pyrolysis zone 40b, and a combustion / melting zone 40c from the upper side to the lower side. The waste 48 introduced into the melting furnace 40 passes through the drying / pre-tropical zone 40a, the pyrolysis zone 40b, and the combustion / melting zone 40c in this order. As a result, the combustible component in the waste 48 is pyrolyzed and gasified and introduced into the combustion chamber, and the ash content becomes molten slag via the pyrolysis residue 43. The molten slag flows down the coke packed bed 41 of the furnace bottom 46 and is discharged from the slag opening 49.

The maximum temperature of the melting furnace 40 is, for example, 1600 ° C. or higher in the combustion / melting zone 40c. By heating in the melting furnace 40 at a sufficiently high temperature in this way, the waste is sufficiently melted, the fluidity of the molten slag is improved, and the formation of needle-shaped slag can be suppressed. The maximum temperature of the melting furnace 40 may be, for example, 1800 ° C. or lower, or 1700 ° C. or lower.

The slag slag from the slag opening 49 may be discharged continuously (continuous slag) or intermittently (intermittent slag). The interval between slags in the case of intermittent slags may be, for example, 30 minutes or more, and may be 1 hour or more. The molten slag discharged from the slag opening 49 is introduced into the crushing tank 10 containing the cooling water and crushed.

FIG. 2 is a diagram schematically showing the granulation tank 10. The molten slag 20 discharged from the slag opening 49 of the melting furnace 40 is introduced into the granulation tank 10 installed below the melting furnace 40. The cooling water 12 is housed in the granulation tank 10, and the molten slag 20 falls into the cooling water 12. The temperature of the molten slag 20 decreases and the viscosity of the molten slag 20 increases due to contact with the atmosphere from the outlet 49 to the cooling water 12.

The viscosity of the molten slag 20 upon contact with the cooling water 12 is 5 Pa · s or less. Here, the "viscosity of the molten slag at the time of contact" means the viscosity of the molten slag immediately before the contact with the cooling water 12. Normally, the temperature of the molten slag 20 that falls from the slag port 49 toward the cooling water 12 of the granulation tank 10 gradually decreases as it approaches the cooling water 12. Then, the temperature at the time of contact with the cooling water 12 becomes the minimum temperature of the molten slag 20, and the viscosity at this time becomes the maximum value of the viscosity of the molten slag 20. Therefore, by setting the viscosity of the molten slag 20 when it comes into contact with the cooling water 12 to 5 Pa · s or less, the stringing phenomenon of the molten slag 20 can be suppressed and the formation of needle-shaped slag can be suppressed.

The viscosity of the molten slag 20 upon contact with the cooling water 12 is preferably 4 Pa · s or less, and more preferably 3 Pa · s or less, from the viewpoint of further reducing needle-shaped slag. The lower limit of the viscosity may be, for example, 1 Pa · s. This viscosity may be adjusted by changing the composition and the amount of auxiliary materials to be charged.

The temperature of the molten slag 20 upon contact with the cooling water 12 (that is, the minimum temperature of the molten slag 20) may be 1300 to 1400 ° C. The temperature difference between the molten slag 20 at the slag opening 49 and the molten slag 20 when in contact with the cooling water 12 may be 40 ° C. or higher, or 100 ° C. or higher. The temperature difference may be less than 300 ° C. from the viewpoint of lowering the viscosity of the molten slag 20 when it comes into contact with the cooling water 12. This temperature difference can be adjusted by changing the temperature of the atmosphere in which the molten slag falls and the distance between the outlet 49 and the water surface of the cooling water 12.

The difference between the maximum temperature of the melting furnace 40 and the temperature of the molten slag 20 when it comes into contact with the cooling water 12 may be 200 ° C. or higher, or 250 ° C. or higher. The difference may be less than 400 ° C. from the viewpoint of lowering the viscosity of the molten slag 20 when it comes into contact with the cooling water 12.

The step of measuring the temperature of the molten slag 20 when it comes into contact with the cooling water 12 may be performed by using a temperature measuring device 25 provided above the water surface of the cooling water 12. The temperature measuring device 25 may be a radial temperature measuring device. If the composition of the molten slag 20 is constant, by monitoring the temperature of the molten slag 20 when it comes into contact with the cooling water 12, the viscosity of the molten slag 20 when it comes into contact with the cooling water 12 is stable within the target range. Can be maintained at.

A granulation nozzle 14 is provided in the cooling water 12 of the granulation tank 10. For example, a pump (not shown) is connected to the granulation nozzle 14, and the granulation nozzle 14 discharges the cooling water supplied from the pump. As a result, a water flow is generated in the surface layer portion of the cooling water 12. When this water flow collides with the molten slag 20, the molten slag 20 is smoothly cooled and granulated.

The temperature of the cooling water 12 in the granulation tank 10 rises due to contact with the molten slag 20. Therefore, the temperature of the cooling water 12 in the granulation tank 10 may be controlled within a predetermined range by using a cooler (not shown). The molten slag 20 is cooled and granulated by coming into contact with the cooling water 12 in the granulation tank 10, and becomes granulated slag. The granulated slag is conveyed by a scraper conveyor 15 provided at the bottom of the granulated tank 10 and discharged to the outside of the granulated tank 10. In this way, granulated slag is obtained. The content of needle-shaped slag in the granulated slag thus obtained is sufficiently reduced. Therefore, the work efficiency in the post-process can be improved.

As an example, the waste melting treatment method may include a step of crushing and separating the granulated slag to obtain a waste melted slag powder having a needle-shaped slag content of 0.5% by mass or less. This step can be performed in the crushing section 30 and the sieving section 35 in FIG. When the granulated slag contains metal, the metal component may be removed or reduced by a magnetic separator before or after the crushing unit 30. The crushing in the crushing unit 30 may be performed using at least one of a crushing device and a crushing device. An example of a crushing device is a type (impact crushing type) in which granulated slag is crushed in a crushing chamber provided with rotating teeth and fixed teeth. An example of a grinding device is a type (high-speed centrifugation method) in which a wall surface of a molten slag is formed by a rotating drum and then flows and is ground with the molten slag introduced from above.

The crushing by the crushing unit 30 may be performed so that the particle size of the granulated slag is, for example, 5 mm or less, preferably 2.5 mm or less. After that, the slag sorting unit 35 may perform sieving to remove coarse slag particles. As the sieve, for example, a metal mesh sieve having a nominal opening of 4 to 11.2 mm specified in JIS Z8801-1: 2006 may be used. The powder that has passed through such a sieve can be obtained as waste molten slag powder.

Even if such sieving is performed, the needle-shaped slag that is thinner than the opening of the sieve passes through the sieve and is contained in the waste molten slag powder. Since the content of needle-shaped slag in the granulated slag of the present embodiment is sufficiently reduced, the content of needle-shaped slag in the waste molten slag powder can be sufficiently reduced. Therefore, the work efficiency until the waste molten slag powder is obtained can be sufficiently improved.

Among the above-mentioned waste melting treatment methods, the aspect of obtaining the waste molten slag powder can also be referred to as a method for producing the waste molten slag powder. That is, the method for producing the waste molten slag powder according to the embodiment can be carried out in the same manner as the above-mentioned waste melting treatment method.

The waste molten slag powder thus obtained has a sufficiently reduced content of needle-shaped slag. The content of needle-shaped slag in the waste molten slag powder according to one embodiment is 0.5% by mass or less, preferably 0.3% by mass or less, and more preferably 0.2% by mass or less. , More preferably 0.1% by mass or less. As described above, by sufficiently reducing the content of the sharp needle-shaped slag, the work efficiency can be further improved. The lower limit of the content of the needle-shaped slag may be 0.005% by mass or more from the viewpoint of facilitating production.

The waste molten slag powder may have the same composition as the molten slag 20 discharged from the slag opening 49. That is, the total content of MgO and FeO in the waste molten slag powder is preferably 4% by mass or more, more preferably 6% by mass or more, and further preferably 8% by mass or more. Such waste molten slag powder has a sufficiently reduced content of needle-like components that are not classified as needle-like slag. From the same viewpoint, the content of MgO in the waste molten slag powder may be 1% by mass or more. The FeO content in the molten slag may be 1% by mass or more.

From the viewpoint of reducing the charge amount of the auxiliary material and reducing the manufacturing cost, the total content of MgO and FeO in the waste molten slag powder may be less than 20% by mass and may be less than 15% by mass. .. From the same viewpoint, the content of MgO in the waste molten slag powder may be less than 12% by mass and may be less than 10% by mass. From the same viewpoint, the content of FeO in the waste molten slag powder may be less than 15% by mass and may be less than 12% by mass.

The waste molten slag powder may contain components other than MgO and FeO. For example, it may contain at least one selected from the group consisting of CaO, SiO ₂ , Al ₂ O ₃ and MnO. The basicity (CaO / SiO ₂ ) of the waste molten slag powder may be 0.5 to 1.2.

The particle size of the waste molten slag powder passes through a metal mesh sieve having a nominal opening of 4.75 mm specified in JIS Z8801-1: 2006, preferably 85% or more, more preferably 100% by mass percentage. Is preferable. The waste molten slag powder having such a particle size is excellent in handleability and can be suitably used for various uses.

Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment. For example, the structure and shape of the waste melting treatment facility are not limited to those shown in the figure.

The contents of the present disclosure will be described in more detail with reference to Examples and Comparative Examples, but the present disclosure is not limited to the following examples.

[Preliminary experiment]
<Test on the ease of sticking needle-shaped slag>
Waste molten slag powder was produced in a waste melting treatment facility equipped with a coke bed type melting furnace as shown in FIGS. 1 and 2. From the obtained molten slag powder of waste, slag having a needle-like shape was taken out and classified into the following three (1) to (3) according to the length. The "length" here is the length of a line segment connecting both ends of a slag having a needle-like shape.
(1) Length: 10 mm or more (2) Length: 5 mm or more and less than 10 mm (3) Length: less than 5 mm

FIG. 3 is a photograph of a needle-shaped slag having a length of 10 mm or more. FIG. 3A shows the entire slag having a needle-like shape, and FIG. 3B shows the smaller of both ends of one slag arbitrarily selected from FIG. 3A. The end (tip) of is enlarged and shown. FIG. 4 is a photograph of a slag having a length of 5 mm or more and less than 10 mm. FIG. 4A shows the entire slag having a needle-like shape, and FIG. 4B shows the smaller of both ends of one slag arbitrarily selected from FIG. 4A. The end (tip) of is enlarged and shown. FIG. 5 is a photograph of a slag having a length of less than 5 mm. FIG. 5A shows the entire slag having a needle-like shape, and FIG. 5B shows the smaller of both ends of one slag arbitrarily selected from FIG. 5A. The end (tip) of is enlarged and shown.

The thickness of the tip of each slag having a needle-like shape was measured. The length and thickness of the slag were measured using a digital microscope (KEYENCE Co., Ltd., model: VHX-6000) at a visible magnification of 20 to 2000 times. The measurement was performed for 4 to 5 pieces in each of the categories (1) to (3). The measurement results are as shown in Table 1.

As shown in Table 1, it was confirmed that as the length of the slag increased, the tip portion became thinner and tended to become sharper. Next, both ends of the slag were gripped so as to be pressed against the thumb and index finger, and the thumb and index finger were brought close to each other and gripped for 10 seconds. After that, it was evaluated whether or not the slag stuck in the finger when the thumb and the index finger were released. Four to five slags were selected from the classifications (1) to (3), and each slag was gripped and evaluated with the same force every day. "D" when all slags are stabbed, "C" when 3-4 slags are stabbed, "B" when 1 or 2 slags are stabbed, without sticking one finger The case where all of them fell was evaluated as "A". The evaluation results are as shown in Table 2.

As shown in Table 2, it was confirmed that the larger the length of the slag, the thinner the tip portion, so that the slag is more likely to be stuck in the finger without falling. A slag having a length of 5 mm or more is clearly easier to pierce a finger than a slag having a length of less than 5 mm. Therefore, a slag having a length of 5 mm or more is called a "needle-shaped slag" and this "needle-shaped slag". It was decided to examine the conditions for suppressing the content of "slag".

[Example 1]
Waste molten slag powder was produced in a waste melting treatment facility equipped with a coke bed type melting furnace as shown in FIGS. 1 and 2. From the charging device, waste mainly including general waste and industrial waste, coke as a charcoal material, and dolomite having the composition shown in Table 3 as an auxiliary material were added. 4% by mass of carbonaceous material and 2% by mass of dolomite were charged with respect to 100 parts by mass of waste. The maximum temperature in the melting furnace was 1600 ° C. When the operation of the melting furnace was in a stable state, the temperature of the molten slag at the outlet was measured with a radiant thermometer and found to be about 1500 ° C. This molten slag was sampled in a platinum crucible.

The temperature immediately before the molten slag fell toward the granulation tank and came into contact with the cooling water in the granulation tank was measured with a radiant thermometer and found to be 1362 ° C. Therefore, the molten slag (about 1500 ° C.) sampled in the platinum crucible as described above was placed in the platinum crucible, the temperature was gradually lowered while rotating the rotor in the crucible, and the viscosity at 1362 ° C. was measured. The results are shown in Table 4. The FeO content in the molten slag was measured according to JIS A5011-3: 2016. In addition, the MgO content in the molten slag was measured according to JIS A5011-3: 2016. The measurement results are as shown in Table 4.

The granulated slag obtained by introducing it into a granulator was recovered, metal was removed by a magnetic separator, and then pulverized using a shock crushing type crushing device and a high-speed centrifugal type crushing device. The crushed granulated slag was sieved using a sieve having a mesh size of 5 mm (nominal opening specified in JIS Z8801-1: 2006: 4.75 mm). The powder that passed through this sieve was used as the waste molten slag powder of Example 1.

Needle-shaped slag was selected from the obtained molten waste slag powder (10 g), the total mass of the needle-shaped slag was measured, and the mass ratio was determined. The results are shown in Table 4 as the content of needle-shaped slag. In addition, the FeO content and MgO content in the waste molten slag powder were measured by the same method as when analyzing the molten slag. The measurement results are as shown in Table 4.

[Example 2]
As an auxiliary material, the waste melting treatment equipment was charged in the same manner as in Example 1 except that steel slag having the composition shown in Table 3 was charged in place of dolomite in an amount of 3% by mass with respect to 100% by mass of the waste. I drove. The molten slag was sampled in the same manner as in Example 1, and the viscosity at the temperature immediately before the molten slag came into contact with the cooling water in the granulator was measured. In addition, the content of needle-shaped slag in the waste molten slag powder obtained in the same manner as in Example 1 was determined. These results are shown in Table 4.

[Comparative Example 1]
The waste melting treatment equipment was operated in the same manner as in Example 1 except that limestone having the composition shown in Table 3 was charged instead of dolomite as an auxiliary material. The molten slag was sampled in the same manner as in Example 1, and the viscosity at the temperature immediately before the molten slag came into contact with the cooling water in the granulator was measured. In addition, the content of needle-shaped slag in the waste molten slag powder obtained in the same manner as in Example 1 was determined. These results are shown in Table 4.

As shown in Table 4, it was confirmed that the content of needle-shaped slag can be reduced by lowering the viscosity of the molten slag immediately before contacting with the cooling water. FIG. 6 is a photograph of the waste molten slag powder of Comparative Example 1. As shown at the bottom of the photo, the waste molten slag powder contained a relatively large amount of needle-shaped slag. On the other hand, in Examples 1 and 2, the content of needle-shaped slag was significantly lower than this.

[Comparative Examples 2-1 and 2-2, Examples 3-1 and 3-2]
The change in viscosity when the composition of molten slag (waste molten slag powder) was changed by changing the blending ratio of steel slag and dolomite used as auxiliary materials was investigated. Specifically, the content of FeO in the molten slag is 1.4 to 1.7% by mass while the basicity (CaO / SiO ₂ ) is maintained at about 0.9, so that 100% by mass of waste is used. 1 to 2% by mass of steel slag was added to the amount. Using a fluorescent X-ray analyzer (manufactured by Spectris, device name: Epilon3), the amount of dolomite added is in the range of 0 to 5% by mass while appropriately measuring the chemical composition value of the molten slag discharged from the outlet. The MgO content was changed as shown in Table 5. In each composition shown in Table 5, the viscosity of the molten slag immediately before contacting with the cooling water was measured. The results are as shown in Table 5.

[Examples 4-1 to 4-4]
The change in viscosity when the composition of molten slag (waste molten slag powder) was changed by changing the blending ratio of steel slag and dolomite used as auxiliary materials was investigated. Specifically, since the content of MgO in the molten slag is 1.7 to 2.1% by mass while the basicity (CaO / SiO ₂ ) is maintained at about 0.9, it is added to 100 parts by mass of waste. On the other hand, 1 to 2 parts by mass of dolomite was added. Using a fluorescent X-ray analyzer (manufactured by Specris, device name: Epilon3), the amount of steel slag added is 0 to 8% by mass while appropriately measuring the chemical composition value of the molten slag discharged from the outlet. The FeO content was changed as shown in Table 6 by adjusting the range. In each composition shown in Table 6, the viscosity of the molten slag immediately before contacting with the cooling water was measured. The results are as shown in Table 6.

FIG. 7 is a graph in which the data in Tables 5 and 6 are plotted. That is, FIG. 7 shows the relationship between the total content of FeO and MgO of the molten slag and the viscosity of the molten slag immediately before contacting with the cooling water. It was confirmed that the viscosity of the molten slag immediately before contacting with the cooling water can be reduced by increasing the total content of FeO and MgO.

[Reference Example 1]
FIG. 8 is a photograph of waste molten slag powder distributed in the market. As shown in the lower part of the photograph, the waste molten slag powder contained more needle-like slag than in Comparative Example 1. The content of needle-shaped slag in this waste molten slag powder was 1% by mass.

According to the present disclosure, it is possible to provide a waste melting treatment method capable of improving work efficiency. Further, it is possible to provide a waste molten slag powder capable of improving work efficiency and a method for producing the same.

10 ... pyrolysis tank, 12 ... cooling water, 14 ... granulation nozzle, 15 ... scraper conveyor, 20 ... molten slag, 25 ... temperature measuring instrument, 30 ... crushing part, 35 ... sieving part, 40 ... melting furnace, 40a ... Dry / pre-tropical, 40b ... Pyrolysis zone, 40c ... Combustion / melting zone, 41 ... Coke filling layer, 42 ... Shaft part, 43 ... Pyrolysis residue, 44 ... Morning glory part, 45 ... Upper tuyere, 46 ... Furnace Bottom, 47 ... lower tuyere, 48 ... waste, 49 ... outlet, 50 ... charging device, 52 ... exhaust gas pipe, 100 ... waste melting treatment equipment.

Claims (8)

A waste melting treatment method in which a waste and an auxiliary material containing one or both of a magnesium component and an iron component are melted in a coke bed type melting furnace.
A step of heating the waste and the auxiliary materials to 1600 ° C. or higher in the melting furnace to melt them.
The process of discharging molten slag from the melting furnace and
It has a step of introducing the molten slag into a water crushing tank and crushing the water.
A waste melting treatment method in which the viscosity of the molten slag when in contact with the cooling water in the granulation tank is 5 Pa · s or less. The auxiliary material contains both magnesium and iron components.
The waste melting treatment method according to claim 1, wherein the total content of FeO and MgO in the molten slag is 4% by mass or more. The waste melting treatment method according to claim 1 or 2, further comprising a step of measuring the temperature of the molten slag when it comes into contact with the cooling water in the granulation tank. One of claims 1 to 3, which comprises a step of obtaining a waste molten slag powder having a needle-shaped slag content of 0.5% by mass or less from the granulated slag obtained by hydrolyzing in the granulation tank. The waste melting treatment method according to. Waste molten slag powder having a needle-like slag content of 0.5% by mass or less. The waste molten slag powder according to claim 5, wherein the total content of FeO and MgO is 4% by mass or more. A step of heating the waste and auxiliary materials containing one or both of the magnesium component and the iron component to 1600 ° C. or higher in a coke bed type melting furnace to melt them.
The process of discharging molten slag from the melting furnace and
The process of introducing the molten slag into a granulation tank and granulating it to obtain granulated slag.
It has a step of obtaining a waste molten slag powder from the granulated slag.
A method for producing a waste molten slag powder, wherein the viscosity of the molten slag when it comes into contact with cooling water in the granulation tank is 5 Pa · s or less. The method for producing a waste molten slag powder according to claim 7, wherein the content of the needle-shaped slag of the waste molten slag powder is 0.5% by mass or less.

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