JP3508071B2 - Manufacturing method and manufacturing apparatus of granular artificial aggregate for concrete - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a granular artificial aggregate for concrete, and more specifically, melting incinerated ash of domestic waste or industrial waste or sewage sludge dry powder, and the incinerated ash. Melt-reduces easily-reducible metal oxides contained in etc. and produces molten slag mainly composed of mineral substances such as SiO ₂ and produces artificial aggregate extremely close to natural stone and natural gravel from the molten slag. It is about technology.

[0002]

2. Description of the Related Art Domestic waste and industrial waste are incinerated, and sewage sludge, etc., is reduced to dry powder,
Discarded in landfills. However, there is a limit to the amount of dumped land, and it is becoming possible to further reduce the volume and reuse it as a resource. Recently, research has been advanced from the viewpoint of recycling resources, and composting and recovery of valuable materials have also been carried out. Although detoxification treatment is important for such recycling, the same applies to the case of recycling building materials and the like from the molten slag of incinerated ash, which has been receiving particular attention.

When incinerator ash is melted at a temperature of 1,500 ° C. or higher, harmful substances such as combustible substances and dioxins in the garbage are completely gasified and burned, and heavy metals are trapped in glassy slag. The advantage is that the volume of incinerated ash can be reduced to 1/3. This melts even the inorganic components in the incinerated ash to form a melt, which is disclosed in JP-A-3-27513.
This is because the solidified slag can be obtained by cooling it as described in Japanese Patent Laid-Open No.

By the way, the slag can be used as a roadbed material or an aggregate for building civil engineering, or can be processed into tiles and ornaments by molding. In any case, it goes without saying that detoxification and chemical stability are required, but various devices for producing such molten slag have been proposed. Typical examples include those using various furnaces such as a swirling melting furnace, a coke bed, a surface melting furnace, an arc furnace, and a plasma furnace.

[0005]

For example, in a coke bed type melt treatment process, a small amount of coke and lime are added to a treated product and the mixture is charged into a vertical furnace (low shaft furnace) at a time, After the preheating / drying zone and the thermal decomposition zone of 300 ° C to 1,000 ° C in the middle stage, combustion in the bottom stage
The melt is lowered to the melting zone to obtain a melt in an atmosphere of a temperature of 1,500 ° C. or higher due to an exothermic reaction of coke supplied with air. Iron and the like are separated by the reducing action of coke, the basicity is adjusted with lime, and the melt is taken out. Rapid cooling gives sandy slag, while slow cooling gives lumpy slag.

The above process for melting incinerated ash in a red-hot coke bed layer using a vertical shaft furnace was developed with the hint of cupola melting. In this system, unlike the case of a blast furnace (high shaft furnace) where coke is effectively used for both direct reduction and indirect reduction,
Since it is a low shaft furnace, only direct reduction is used. That is, all the CO ₂ produced by the reaction between the red hot coke in the lower layer portion and O ₂ reacts with the coke in the upper layer portion, the reduction reaction of CO ₂ + C → 2CO proceeds, and the CO ₂ is discharged as it is from the system. Therefore, the exhaust gas becomes a gas mainly composed of CO and N ₂ . When evaluated from the viewpoint of heat energy, the calorific value when the coke completely burns is 8,080 Kcal, while the calorific value used in the above system is 2,425 Kcal, which is about 30% of the total calorific value. There is a very low defect rate (%).

Coke as fuel is (air + O ₂ )
It is necessary to adjust the particle size to about 10 mm to 35 mm, which is suitable for enriched blast, and it is not possible to use an inexpensive coke breeze. In addition, since coke is used, the generation of coke ash is inevitable, and Al ₂ in the molten slag is
It also increases the content of O ₃ by 1% to 2%. Since the increase of Al ₂ O ₃ deteriorates the fluidity of slag, in order to correct this, it is necessary to increase the amount of lime to prevent the increase of sulfur in the exhaust gas. As a result, the content of CaO in the generated slag becomes high, and the digestible substance of the slag increases, and eventually it becomes unsuitable as an aggregate for concrete.

Different from the above, some of them are melted by using an electric furnace. Although the incineration ash has a drawback that it has a large resistance at room temperature and is difficult to be energized, the incineration ash has a low resistance at a high temperature and becomes relatively conductive when melted. When an electric current is applied to the melt, Joule heat is generated due to the electric resistance of the molten ash, which can be utilized. An electric furnace used for such a melting process includes a submerged arc furnace described later.

By the way, in the case of arc melting in an electric furnace, when an appropriate voltage is applied to an artificial graphite electrode rushed into the furnace, the electric arc flies from the tip of the electrode rod toward incinerated ash or slag, and other electrodes An electrical circuit is formed that leads to the rod and the preformed base metal. In this way, the device that generates the molten slag by arc heating with an electric furnace,
It is described in JP-A-4-354578. In this type of electric furnace, arc discharge is generally 3,000
The temperature is very high at 0 ° C to 5,000 ° C and high speed, and the heat transfer efficiency is high because it collides with the incineration ash and slag while drawing in the surrounding gas, and the incombustibles and metals in the incineration ash are short It can be melted. This has the advantage that it does not require auxiliary materials for adjusting the basicity or lowering the melting point, regardless of the composition of the incinerated ash, and exhibits a high volume reduction effect.

However, in such a conventional electric furnace, the slag outlet is always in an open state, and the slag outlet portion is extremely worn out, and after a few months of operation, a repair suspension period of about one month is required. . Further, since the molten slag is continuously discharged, the iron oxide in the slag is set to 4% to 30%, or the molten slag is exposed to the atmosphere (oxidizing atmosphere). It does not come out. On the other hand, the above-described submerged arc electric furnace is intended to melt the slag by electric arc or electric resistance Joule heat in a state where the slag in the furnace is entirely covered with incinerated ash.

In most of the various melting methods using the swirling melting furnace and the like listed above, since the incineration ash is melted in the combustion gas, a large amount of gas is contained in the outflow slag. However, the submerged arc electromelting method has a great advantage that gas is hardly mixed in the molten slag and defoaming treatment is not required. When the slag discharged from the submerged arc electric furnace is gradually cooled to produce a granular or gravel artificial aggregate, steps such as water cooling or slow cooling of the molten slag are performed. However, as the cooling progresses rapidly, it becomes an amorphous material far from natural stone, and its use is limited. That is, it is difficult to obtain a high-quality artificial aggregate for concrete as a building material, and it can only be used as a roadbed material or a material for green agricultural land that can be used even in an amorphous state.

By the way, Japanese Patent Laid-Open No. 64-52637 discloses a granulation method in which molten slag is splashed into a rotary hood by a rotating blade, and water mist is sprayed on the scattered slag to cool it. Has been done. Further, Japanese Patent Application Laid-Open No. 2-64046 describes a method of passing molten slag through a rotating drum having cooling water sprinkled on its outer surface to solidify the molten slag. In any case, it is not easy to completely crystallize the slag, let alone JP-A-64-5.
As described in Japanese Patent No. 2637, when water is sprinkled on the molten slag that has been scattered, the inside of the slag is solidified in an amorphous state, and as described above, the slag particles are far from the natural stone. Incidentally, Japanese Patent Laid-Open No. 62-37686 discloses a conveyor device which is capable of air-cooling while transporting molten slag and forming a solidified slag having a small and uniform size. However, it is inevitable that the molten slag becomes amorphous because the molten slag is rapidly cooled on the cooling pan during the transportation by the conveyor.

By the way, in order to make the molten slag close to natural stone, the slag must be crystallized to strengthen the structure. For example, Japanese Patent Application Laid-Open No. 4-132642 describes a method of controlling the cooling rate of the molten slag so as to be changed for every several temperature ranges. further,
Japanese Patent Laid-Open No. 3-275539 discloses that crystallized slag is produced by adjusting the components of the molten slag and controlling the cooling rate. However, these have mineralogical questions, and because they are intended to contain harmful substances and metal components in the slag, it is necessary to abandon the collection of substances that can be reused if they can be separated in advance. There are drawbacks such as becoming slag and slag being far from natural stone.

By the way, garbage and sewage sludge are treated by each municipality. In other words, the principle is that collection, incineration, etc. are processed within the area and consumed within the area. Needless to say, the high-temperature treatment method is preferable to the low-temperature treatment method in which elution of heavy metals is inevitable for recycling the ash after incinerating such wastes, and the above-mentioned several melting treatment forms are adopted. On the other hand, it is inevitable that the amount of incinerated ash will vary greatly depending on the local government, but the amount of waste and sewage sludge to be treated should be balanced with the capacity of the incinerator and the amount of consumption within the area when reusing the recovered resources. There is a need. as a result,
In order to meet the processing capacity and consumption, it is often the case that the equipment for melting and slagging the incineration ash and the like generated from the incineration equipment in the area is small in capacity. However, the above-mentioned melting equipment tends to be increased in size, and the appearance of small-sized and small-capacity equipment is desired.

The present invention has been made in view of the above background, and an object thereof is to facilitate miniaturization suitable for melting a relatively small amount of incinerated ash or the like suitable for treatment / consumption within the own area. It can be used as a facility, can reduce the energy required for crystallization of the molten slag by reducing the dissipation of the energy input to the melting of the incineration ash, and can separate the easily reducible metal content in the molten slag. Granular artificial aggregate for concrete that makes it possible to reuse it and manufactures a highly safe so-called natural stone or a hard construction material that is extremely close to river gravel with the minimum content of harmful substances. The manufacturing method and apparatus of

[0016]

The present invention is applied to a method for producing an artificial aggregate for concrete from slag obtained by melting incinerated ash of garbage, dried powder of sewage sludge and the like. As for the feature, referring to FIG. 1, incineration ash etc. 4 containing coke breeze is reduced and melted by a submerged arc electric melting method, and Fe / Cr.
A molten pig iron 5 is produced by reducing a metal oxide such as P, and a molten slag 6 having a low gas content and containing SiO ₂ or the like as a main component is produced in the upper layer portion of the molten pig iron 5. Next, when the molten slag 6 is discharged every 2 to 3 hours, the molten slag 6 is extracted in a short time in order to suppress the heat dissipation from the molten slag 6 and immediately rolled in contact with the water cooling wall to melt. The slag 6 is granulated and the sand preheated to a high temperature is coated to prevent the molten slag particles from being rapidly cooled, and the granular slag 7 having the surface solidified is sieved to remove the mixed sand. Finally, the granular slag 7 is accumulated in the furnace body 3A while the temperature is not lowered to 800 ° C. or lower, and the granular slag 7 is placed in a temperature atmosphere of 800 ° C. to 900 ° C. for 3 to 4 hours, so that the gas content can be extremely reduced. This is to generate a slag having a low texture and dense crystallization.

The invention of the manufacturing apparatus comprises an electric melting furnace 1, a granular slag molding apparatus 2, a hot screen 10 and a rotary heat treatment furnace 3. The electric melting furnace 1 generates molten pig iron 5 by melting and reducing easily-reducible metal oxide from incineration ash 4 or the like containing coke breeze, and also generates molten slag 6 not containing the above metal components. Is. The granular slag forming apparatus 2 cools the molten slag 6 through a water-cooled iron shell, and a slag receiving trough 2A that receives the molten slag 6 that has been slagged in a short time in order to suppress heat dissipation from the electric melting furnace 1. The rotating drum 2C inclined downward so as to move the granular slag in the axial direction in the drum by repeating rolling by rising and falling, and the outer surface of the rotating drum 2C. The drum cooler 2D for spraying the cooling water on the inside, and the high-temperature preheating sand 8 on the granular slag 7 moving in the discharge direction inside the rotary drum 2C.
And a preheated sand feeder 2E for mixing. The hot screen 10 receives the high temperature granular slag 7 discharged from the granular slag molding apparatus 2 together with the preheated sand 8 and sifts off the mixed sand. The rotary heat treatment furnace 3 adds a rotary furnace body 3A into which the high temperature granular slag 7 discharged from the hot screen 10 is introduced from one end opening, a backing refractory wall 3a of the rotary furnace body 3A, and a surface layer of deposited slag. A heating burner 3B for heating is used, and the outer shell is amorphized by the heating action by the refractory wall 3a that has wrapped around the lower portion of the deposited slag by the rotation of the furnace body and the reheat action from the molten portion in the slag. The granular slag 7 present is heat-treated to produce a slag in which a structure having an extremely low gas content is densely crystallized.

Instead of the above rotary heat treatment furnace, the high temperature granular slag 7 from the hot screen 10 is charged from the upper end opening, and the outer shell is made amorphous by the recuperative action from the molten portion in the slag. A vertical shaft furnace may be employed in which the granular slag 7 present is heat-treated to produce a slag in which a structure having an extremely low gas content is densely crystallized.

Another invention of the manufacturing apparatus will be described with reference to FIG.
Granular slag molding device 2 and hot screen 10 described above
The granular slag heat-insulating transfer device 14 is disposed between and. The granular slag heat transfer device 14 heats the high temperature granular slag 7 discharged from the granular slag molding device 2 into the preheating sand 8
A plate conveyor 14A that receives and conveys the sand 15 and a sand spreader 14B that spreads the sand 15 preheated to a high temperature on the plate conveyor 14A are provided.

Although a rotary heat treatment furnace is used in the example of FIG. 4, a vertical shaft furnace may be used instead.

[0021]

According to the present invention, incinerated ash, dried powder of sewage sludge, etc. are reduced and melted to form easily reducible metal oxides as molten pig iron, and no harmful substances having a small gas content are contained. Molten slag can be produced. Then, the molten slag is crystallized to produce a chemically stable and detoxified dense granular slag, which is very close to natural stone.
It becomes a high-quality artificial aggregate for concrete, which is composed mainly of mineral substances such as O ₂ . Molten pig iron can be used as an iron source material for steelmaking and casting, and metal resources are also recovered from incineration ash and the like. In the short-time slag from the electric melting furnace, the heat dissipation of the molten slag is suppressed as much as possible, and the granulating step before entering the crystallization processing step and the transfer step before and after the crystallization step can be performed quickly. Therefore, the high heat energy possessed by the slag can be reheated and used for crystallization, and the energy consumption required for crystallization can be reduced.

According to the artificial aggregate manufacturing apparatus equipped with the electric melting furnace, the granular slag forming apparatus, the hot screen, and the rotary heat treatment furnace, the cooling and rolling motion of the molten slag by the water-cooled rotating drum are utilized. Granular slag is formed from the molten slag and is processed in a rotary heat treatment furnace to obtain granular aggregate close to natural gravel. In a rotary heat treatment furnace, granular slag that directly touches the heated refractory wall or burner flame that wraps around the deposited slag after being heated by a heating burner is exposed to a uniform temperature atmosphere of 800 ° C to 900 ° C. Get burned. The solidified outer shell of the granular slag reaches the temperature required for remelting and crystallization due to the temperature inside the furnace and the heat recovery from the high temperature molten portion inside the slag. After being retained for 3 to 4 hours, the individual granular slags become aggregates with a finely crystallized structure as a whole. The manufacturing equipment as a whole can be easily miniaturized and reduced in capacity, making it easy to make equipment of a scale suitable for processing within the area and consumption within the area.

Even when a vertical shaft furnace is used instead of the rotary heat treatment furnace, it is possible to heat treat the granular slag whose outer shell is made amorphous by the recuperative action from the molten portion in the slag,
It is possible to generate a slag in which a structure having an extremely low gas content is densely crystallized. In this case, it is possible to increase the size of the furnace body, increase the heat treatment amount of the slag, and increase the treatment time. Since the amount of slag contained becomes large, the heat energy brought into the furnace accompanying the granular slag is also large, and the heat loss during the crystallization process is small.

When the granular slag heat-insulating transfer device is arranged between the granular slag molding device and the hot screen,
Even in the presence of unsheathed granular slag, time is allowed to solidify the surface during transfer.
Then, in the rotary heat treatment furnace, gravel-like aggregate in which the structure is densely crystallized is manufactured.

When a vertical shaft furnace is adopted instead of the rotary heat treatment furnace, a large amount of gravel slag can be heat treated.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method and an apparatus for manufacturing a granular artificial aggregate for concrete according to the present invention will be described in detail below with reference to the drawings showing the embodiments. FIG. 1 is an example of an apparatus for producing granular artificial aggregate for concrete from slag obtained by melting incinerated ash of refuse, dried powder of sewage sludge, etc., and its main configuration is an electric melting furnace 1 and a granular slag molding apparatus. 2 and a rotary heat treatment furnace 3.

The electric melting furnace 1 may be any type of three-phase, single-phase AC electric furnace or DC electric furnace, but it is an example of a simplified DC electric furnace in the drawing.
In this case, the raw material 4 is a mixture of incinerated ash and sewage sludge dry powder with coke breeze in advance. The incineration ash is incinerated in an incinerator (not shown) by dewatering refuse or sewage sludge, and the dried sewage sludge powder is dewatered sewage sludge. The electric melting furnace 1 is adapted to melt and reduce incineration ash mixed with coke breeze by a submerged arc electric melting method over time. Then, the metal oxides such as Fe, Cr, P, etc. in the raw material, which are easily reduced, are reduced to produce molten pig iron 5, and the molten slag 6 containing, as a main component, a mineral substance such as SiO ₂ which does not contain the above metal components. Is generated.

A movable electrode 1B which moves up and down at the center is arranged on the furnace ceiling 1A, and a screw feeder or chute (not shown) for supplying incinerator ash 4 which is a powder or granular material through the furnace ceiling is attached. On the side of the furnace body, there is provided a taphole 1a for tapping the molten pig iron 5 that has accumulated in the hearth, intentionally leaving a little. On the other hand, the molten slag 6 staying on the molten pig iron 5
A slag outlet 1b for discharging the slag is also provided, and the slag plug 1d can be pulled out to allow a necessary amount to flow out in a short time in the steps described below. It should be noted that an air supply hole may be provided in the slag plug 1d to supply air for stirring the molten slag in the vicinity of the slag port during melting to prevent clogging of the slag at the time of slag.

When this electric melting furnace 1 is applied to, for example, a refuse incineration facility that produces about 50 tons of incinerated ash per day, the furnace volume is set to accommodate about 4 tons of incinerated ash. this is,
If it takes about 2 hours to melt incinerated ash, etc., 24
This is because the amount of waste will be commensurate with the amount of waste disposal per day, that is, hours / 2 hours × 4 tons = 48 tons. Therefore, a small one with a diameter of about 3 m is enough.

On the downstream side of the electric melting furnace 1, a granular slag molding device 2 composed of a water-cooled drum is installed. This has a charging member composed of a slag receiving gutter 2A and a slag flow suppressing member 2B, a rotating drum 2C, a drum cooling device 2D and a preheating sand supplying device 2E. The slag receiving gutter 2A is for receiving the molten slag 6 slagged from the electric melting furnace 1 every 2 to 3 hours, for example, and is provided with a refractory material and is short enough to suppress the heat radiation of the molten slag 6. It is to be supplied into the rotary drum 2C in time. The slag flow suppressing member 2B having the hanging plate 2b facing the tip portion of the slag receiving gutter 2A reduces the flow force of the molten slag 6 charged from the one end opening of the horizontal drum, and the molten slag rotates. This is to prevent the lower surface of the drum 2C from immediately flowing.

The horizontal rotary drum 2C is a drum whose both ends are open and is not lined with refractory material, so that the cooling water is constantly sprayed from the drum cooler 2D while being rotated by a drive device (not shown). It has become. In this granular slag molding apparatus 2, the molten slag 6 that has flowed in from the one end opening of the rotary drum 2C is cooled through the water-cooled iron shell and repeatedly raised and dropped to generate the granular slag 7 whose surface is solidified. can do. The rotating drum 2C is arranged at a downward inclination so as to form a rounded outer shell while moving the granular slag 7 in the axial direction in the drum, and is rotatably supported by rollers 2a, 2a positioned before and after the rotating drum 2C. .

The preheated sand feeder 2E provided on the outlet side of the rotary drum 2C mixes the high temperature preheated sand 8 with the granular slag 7 moving in the discharge direction in the rotary drum 2C. Heat-retains so that the granular slag 7 is not cooled and solidified inside. That is, preheated sand 8
It suffices that the heat radiation from the granular slag 7 can be suppressed while reaching the rotary heat treatment furnace 3. Therefore, immediately before being introduced into the rotary heat treatment furnace 3, it is removed as described later.

At the outlet of the rotary drum 2C, there is a downwardly inclined transfer chute 9 and a hot screen 10 for receiving the granular slag 7 at 1,000 ° C. or higher. This is a high-temperature granular slag 7 that comes out of the granular slag molding device 2.
The preheated sand 8 mixed in is removed by sieving. The hot screen 10 is, for example, a vibrating screener and has a screen plate 10A.
And a hopper 10B for receiving falling sand. Sieve plate 1
The sand drops from the sieve mesh of 0A, and the slag that has come to the hot screen 10 in the form of lumps due to the vibration at that time is also granulated. The recovered sand has a high temperature due to contact with the granular slag 7, and is returned to the hopper 2e of the preheated sand feeder 2E described above.

A chute 10a is formed at the tip of the sieve plate 10A, and the high temperature granular slag 7 is fed into the rotary heat treatment furnace 3 from the chute 10a. The rotary heat treatment furnace 3 includes a rotary furnace body 3A that is slowly rotated at about 1 rpm, and a heating burner 3B with an air supply pipe for generating a flame therein. In the rotary heat treatment furnace 3, the granular slag 7 having an amorphous outer shell is retained for 3 to 4 hours to generate a slag having a finely crystallized structure. For that purpose, two rotary furnace bodies 3A whose axes are inclined as shown in the figure are provided as shown in FIG. 2, each of which is provided with an opening for charging the granular slag 7 at one end thereof and is lined with fireproof material on the inner surface. A wall 3a is provided (see FIG. 1).

The sandy slag 7 is charged and accumulated in the rotary heat treatment furnace 3 while the temperature is not lowered to 800 ° C. or lower, and the granular slag 7 is heated while heating the refractory wall 3a and the slag deposition surface layer by the heating burner 3B. The temperature is set to 800 to 900 ° C. Then, the granular slag 7 is heat-treated by the heating action of the refractory wall 3a that has circulated below the accumulated slag by the rotation and the action of recuperating the heat retained inside the slag.

Although the rotary furnace body 3A was touched above, it has a capacity commensurate with the amount of the molten slag 6 obtained from the raw material 4 of about 4 tons per 2 hours, and the flame of the heating burner 3B arranged on the axis line. Is a volume that can be charged to such an extent that it touches the deposition surface of the granular slag 7. And two rotary furnace bodies 3
The chute 10a for supplying the granular slag 7 to A and 3A has a structure capable of changing the direction as shown in FIG. The number of the rotary furnace bodies 3A may be one, but the number of the rotary furnace bodies 3A is two. It is based on the consideration that we want to be able to secure time to 4 hours.

According to such an apparatus, a crystallized good quality artificial aggregate for concrete can be produced by melting incinerated ash or the like and heat-treating as follows. First, a powdery raw material 4 in which coke breeze is mixed in advance with incinerated ash or the like is supplied from a charging hole 36 of the furnace ceiling 1A of the electric melting furnace 1 using the screw feeders 35, 35 shown in FIG. The incinerated ash 4 and the like are melted and reduced by the submerged arc electric melting method in 2 to 3 hours. Due to the heat of 1,500 ° C at this time,
Combustibles and dioxins are gasified and burned.

Although the granular material such as incinerated ash has a low specific gravity and low electric conductivity, since coke breeze is mixed in the raw material, the carbon improves the electric conductivity of the raw material and melts the incinerated ash or the like. Is promoted. And F which is easy to reduce
Metal oxides such as e.Cr.P are melt-reduced and molten slag is generated. The CO gas generated by the reaction at that time promotes the forming of the slag. The molten pig iron 5 produced by reduction stays in the hearth as shown in FIG. 1, and the molten slag 6 floats on it. Forming slag 11 is formed on molten slag 6, and carbon floating layer 12 is formed at the boundary between the molten slag 6 and the raw material layer.

The lower part of the movable electrode 1B lowered into the furnace body is covered with a carbon floating layer 12 forming slag 1
1, the arc is always in a submerged state in which it is covered with the raw material 4 and the forming slag 11. Not only heating of the raw material by the arc generated at the carbon floating layer 12 but also the forming slag 11
The efficient melting due to the electric resistance Joule heat from the temperature to the molten pig iron 5 is also realized. This forming slug 1
As is already known, the generation of 1 dramatically improves the power transmission efficiency, so that the power consumption rate can be reduced.

When the incineration ash etc. 4 is successively reduced and melted, in order to maintain the submerged arc state, the raw materials are sequentially added so as to be distributed around the movable electrode 1B through the rotating furnace ceiling 1A from the screw feeder 35. Supplied. The molten pig iron 5 accumulated in the hearth is intentionally left in the hot metal ladle 1M every 1 to 2 days from the tap 1a and is used separately as an iron source material for steelmaking and casting. . On the other hand, the molten slag 6 does not contain metal components such as molten pig iron, and its main components are SiO ₂ , Al ₂ O ₃ , CaO,
It is a mineral substance such as MgO and is in a state of containing almost no gas by the submerged arc melting method. Therefore,
There is no need to subsequently perform defoaming treatment. The molten slag 6 is discharged from the outlet 1b, but is discharged in a short time of, for example, 20 minutes every 2 hours after removing the outlet plug 1d. Therefore, as compared with the case where the generated molten slag is continuously discharged little by little, the amount of heat energy emitted from the molten slag 6 at the time of slag is also suppressed as much as possible.

The molten slag 6 having high heat energy flowing down from the slag receiving gutter 2A is applied to the hanging plate 2b of the slag flow suppressing member 2B. The flow is depressurized and diffused in the drum, and the molten slag 6 is granulated by repeating the rise of the inner peripheral wall and the fall of water by the rotation of the drum while being cooled through the water-cooled iron shell of the rotating drum 2C. . The particle size can be changed by changing the number of rotations of the rotary drum 2C, but since the molten slag 6 is cooled, the surface is solidified. Then, by rolling inside the drum, it becomes a granule having a round outer shell. The sprayed cooling water partially evaporates while flowing around the drum, but the water that has flowed down is dropped into the water reservoir 2d.

The rotary drum 2A rotates at, for example, about 30 rpm, but the cooling water is successively moved on the transfer chute 9 by the draining fins 2f standing on the outer surface of the drum 1,
It does not reach the granular slag 7 at around 000 ° C. Immediately before being discharged from the rotary drum 2C, the sand 8 is supplied from the preheated sand supplier 2E. This sand may be commonly available river sand, but it may be heated separately or the high temperature sand collected by the hot screen 10 may be used. This sand also rises and falls in the rotary drum 2C and is uniformly mixed into the granular slag 7. Such preheated sand 8 prevents heat dissipation of the granular slag 7 and suppresses solidification of the granular slag 7 in an amorphous state.

The granular slag 7 is supplied together with the preheated sand 8 from the granular slag molding device 2 to the hot screen 10 via the transfer chute 9, and the preheated sand 8 is sifted by the sieve plate 10A. Granular slag 7 at around 900 ° C
The rotary heat treatment furnace 3 immediately through the chute 10a.
It is charged into one of the rotary furnace bodies 3A while the temperature is not lowered to 800 ° C or lower.

The rotary furnace body 3A is preheated by the heating burner 3B, and when the granular slag 7 is charged in a predetermined amount, the chute 10a retracts and is slowly rotated at a speed of about 1 rpm. A flame is generated from the heating burner 3B, and the refractory wall 3a and the deposition surface layer of the slag are heated. The granular slag 7 that has come into contact with the heated refractory wall 3a and that has come into direct contact with the flame that has wrapped around the deposited slag due to the rotation of the furnace body 3A is placed in a uniform temperature atmosphere of 800 ° C to 900 ° C. The rotation of the furnace body 3A also promotes granulation of the slag 7. Then, the solidified amorphous outer shell of the granular slag 7 is
Due to the temperature inside the furnace and the heat recovery from the high temperature molten portion within the granular slag 7, the temperature required for remelting and crystallization is reached. After being retained for 3 to 4 hours, the individual granular slag 7 is a hard granular aggregate 7A in which a fine crystallization of the structure is achieved as a whole.
Becomes

After a lapse of a predetermined time, the heating burner 3B is stopped and the product discharge port lid 3b is removed. When the drum was rotated again, it was crystallized every time the discharge port went down.
The granular aggregate 7A of about mm to 20 mm is discharged.
Since the axis of the furnace body 3A is inclined downward from the charging port, the furnace body 3A moves to the discharging port in the furnace body, and all is put into the product receiver 3C. The granular aggregate 7A thus obtained is free from metal components that can be easily reduced in the electric melting furnace 1 as described above, and has a very small gas content, so that uniform crystallization can be achieved. It becomes a chemically stable artificial aggregate for concrete with a dense structure that is accelerated and is very close to natural stone and river gravel. The heat energy applied to the molten slag in the electric melting furnace 1 is quickly lost to the heat treatment step with less loss on the way, and the heat energy consumption for crystallization is also significantly reduced.

As can be seen from the above description, molten pig iron and molten slag are produced by melting incinerated ash or the like, and a high quality artificial aggregate for concrete containing as few harmful substances as possible is produced from the molten slag. be able to. Since the molten pig iron generated at that time can be used separately, metal resources can be recovered. Coke breeze is added to the incineration ash, etc., and the electric conductivity of the raw material is increased to promote melting, and reduction by carbon is realized. Not only that, it also promotes the formation of forming slag and greatly contributes to the reduction of the power consumption rate by improving the power transmission efficiency.
Further, the molten slag is prevented from dissipating the retained heat energy during the short time slag for each predetermined time and the rapid transfer form, and the heating energy for the crystallization operation is also reduced. Further, it is possible to provide a facility that realizes processing of waste and sewage sludge generated in the area and reduction in capacity commensurate with consumption of the product in the area.

FIG. 4 is an overall view of an artificial aggregate manufacturing facility for concrete for obtaining a granular artificial aggregate that is slightly larger than the previous example. In this example, the electric melting furnace 1, the granular slag molding apparatus 2, and the rotary heat treatment furnace 3 are the same as those in the above-mentioned example, and the granular slag heat insulating furnace 3 and the rotary heat treatment furnace 3 are used for keeping the granular slag warm. A transfer device 14 is arranged. It comprises a plate conveyor 14A and a sand spreader 14B. The plate conveyor 14A receives and conveys the high temperature granular slag 7 discharged from the granular slag molding apparatus 2 together with the preheated sand 8. When the distance between the granular slag molding device 2 and the rotary heat treatment furnace 3 is long, the plate conveyor 14A is
Not only is it used to transfer the granular slag 7, but it is also possible to ensure the solidification time of the surface that causes the granular slag 7 to form an outer shell. On the other hand, the sand spreader 14B spreads the hot sand 15 returned from the hopper 10B on the plate conveyor 14A, for example. The plate conveyor 14A may be endless, but it is necessary to sprinkle sand in advance in order to avoid contact with a metal surface, prevent the granular slag 7 from rapidly cooling, and suppress solidification in an amorphous state. Because.

In the apparatus for manufacturing the granular artificial aggregate for concrete in such an example, the granular slag 7 discharged from the granular slag molding apparatus 2 together with the preheated sand 8 passes through the transfer chute 9 and the granular slag heat insulating transfer device 14 is provided. Is supplied to.
The bedding floor sand 15 is previously spread by the sand spreader 14B onto the plate conveyor 14A moving in the direction of the arrow 16. The heat dissipation of the granular slag 7 supplied to the transfer chute 9 is caused by the preheating sand 8
And the bedding sand 15 suppress the granular slag 7 to 90
It is maintained at about 0 ° C. Even if the granular slag 7 having no outer shell is present, only the surface can be solidified during the transfer. Since there is bedding sand 15, the granular slag 7 is easily separated from the tip of the plate conveyor 14A, falls on the hot screen 10, and is charged into the rotary heat treatment furnace 3. The processing in the hot screen and rotary heat treatment furnace is the same as the previous example, and is slightly larger.
It is possible to manufacture the gravel aggregate 7B having a size of about mm to 30 mm.

Although the rotary heat treatment furnace is used in each of the above-mentioned examples, a known vertical shaft furnace (not shown) can be used in place of the rotary heat treatment furnace when the throughput is large. . The amount of slag deposited in the furnace increases, and the heat energy brought into the furnace also increases accordingly, and heat loss during the crystallization process can be reduced. Then, as in the case described above, the slag whose outer shell is amorphized by the recuperative action from the molten portion in the slag can be heat-treated, and the artificial crystallization in which the structure with an extremely low gas content is densely crystallized is achieved. Aggregate is generated. Since the shaft furnace has no movable member, it can be easily increased in size, and the heat treatment amount of the slag can be increased and the treatment time can be lengthened. of course,
If necessary, the inside of the furnace may be heated, but in that case, since it is not necessary to directly apply the flame to the slag, the hot gas may be supplied from an appropriate portion of the furnace wall.

By the way, as described above, the electric melting furnace 1 is a three-phase, single-phase, if it is a submerged arc electric furnace.
Any form of direct current may be adopted. But,
Three-phase AC electric furnaces are generally suitable for large capacity, and
There is a tendency that the direction of arc generation is biased between the electrodes, or only the deposited surface layer of the furnace interior charge is heated. That is, the balance of the melting zone formed under each electrode becomes unbalanced, and it is difficult to realize the gentle reduction melting that is required especially when a powdery material having a low specific gravity and low electric conductivity is used as a raw material. However, it becomes impossible to obtain a uniform heating state. Further, in the single-phase AC electric furnace, the AC power is always reciprocated, so that the heating of the raw material is localized. On the other hand, the electric furnace used as the apparatus for manufacturing an artificial aggregate for concrete is sufficiently small as described above. Therefore, it is optimal to use a DC electric furnace, which has a simple furnace structure, is easy to control, and has the most stable supply of electric energy for the reason described later. An example thereof is shown in FIG.

In the figure, the movable electrode 1 is provided in the electric melting furnace 1.
Although B is inserted, the content of oxide is generally small in the incineration ash and the like to be charged, and the consumption of the electrode is small. Therefore, it is preferable to use the self-baking Zedaberg electrode which is easier to operate and cheaper than the artificial graphite electrode. As a result, the cost associated with electrode consumption can be significantly reduced. On the other hand, as an electrode provided on the furnace side, 0.02%
For example, the L-shaped electrode 1C of the pure iron forged bar of C is shown in FIG.
Four are used as shown in. The electrode 1C is composed of a vertical portion 1v embedded in the furnace wall and a horizontal portion 1y arranged at the furnace bottom as shown in FIG. 3, and the vertical portion 1v is shown in FIG.
As shown by the phantom line, the cross section is substantially square, in which the outward passage 1r for circulating the cooling water and the return passage 1 provided inside thereof are provided.
s and are formed.

The horizontal portion 1y of the L-shaped electrode 1C has a rectangular cross section with a narrow width as shown by an imaginary line in FIG.
As shown in (b), they are arranged radially along the refractory material 1 m of the furnace body. As shown in FIG. 3, this horizontal portion 1y is covered with carbon powder 31 and is stamped in order to expose a surface for arranging a block forming a hearth and to improve electric conductivity. Then, a large number of actually small rectangular graphite blocks 32 are arranged on the surface of the insulating refractory material 1n covering the vertical portion 1v and the carbon stamp 31 so as to form a furnace wall or a hearth. By doing so, as described above, the molten pig iron 5, the graphite block 32, and the carbon stamp 31 staying in the hearth form a wide conductive portion on the bottom of the hearth. The voltage supplied from the plurality of L-shaped electrodes 1C and applied between the movable electrodes 1B and the movable electrodes 1B is likely to be uniformly applied to the entire hearth. In this way, when substantially the same potential level is formed on the hearth surface, the conductive effect of coke breeze mixed in the incineration ash, etc.,
A quick and uniform melting of the raw material is realized by the quiet heating and melting action required for the reduction and melting of powdery granular incineration ash having a low specific gravity and low electric conductivity. Of course, the power consumption is significantly reduced due to the improvement of the power transmission efficiency due to the formation of the forming slag described above.

In this electric melting furnace, since the carbon material is present near the furnace bottom, the reducing atmosphere is maintained,
Even if the horizontal portion 1y of the L-shaped electrode 1C is in a high temperature state, there is no risk of oxidation. On the other hand, the vertical portion 1v is water-cooled as described above because there is a possibility that the vertical portion 1v may come into contact with air and be oxidized when the temperature inside the furnace rises. By the way, the L-shaped electrode 1C is connected to the corbel copper plate 33 arranged around the furnace via the flexible conductive wire 34, and an electric circuit can be formed without being affected even if the furnace body is thermally expanded.

By the way, the incineration ash mixed with coke breeze is a granular material, and in the electric melting furnace 1, the screw feeder 35 is inserted into the charging hole 36 provided in the furnace ceiling 1A.
Is connected and charged so that dust is not scattered to the outside. Of course, not only the screw feeder but also a flexible chute may be connected, but the two charging holes 36, 36 are movable electrodes 1B as shown by the broken line in FIG.
When the furnace ceiling 1A is rotated at different radial distances from, the incineration ash and the like can be uniformly charged into the furnace body. This ensures that the periphery of the movable electrode 1B is covered with the raw material. In addition, incineration ash or the like is supplied to the screw feeder or the like from the upper storage bin 37. By the way,
Two screw feeders 35A, shown in phantom in the figure,
When arranging the three screw feeders at intervals of 120 degrees, including 35A, the raw materials can be introduced more widely and uniformly if the radial distances are different from each other.

As described above, the furnace ceiling 1A rotates, but the storage bin 37 is fixed to the upper deck or the like.
Each screw feeder 35 is separated from the storage bin 37 during rotation. After rotating 180 degrees or 120 degrees, they are reconnected and the hopper 42 connected to the screw feeder 35 is charged with the amount of raw material to be supplied to the furnace body during the next rotation. When a flexible chute (not shown) is connected to the charging hole 36 instead of the screw feeder, the furnace ceiling can be horizontally swung within a range in which the chute can be deformed. In this case, it is not necessary to separate the storage bin from the storage bin, and moreover, it becomes easy to realize hot charging even when the incineration ash or the like is red-hot. As a result, it is possible to achieve a dramatic reduction in power consumption in the electric melting furnace. In addition, when the hot charge is used, the fluidity of the raw material is extremely high, so that there is an advantage that the dispersibility when entering the furnace interior is good and the swing range of the furnace ceiling can be made small.

The drive for rotating the furnace ceiling 1A is realized by the gear mechanism 38 shown in FIGS. 3 and 6, and the swinging is realized by a mechanism using a cylinder or a link (not shown). In either case, the furnace ceiling 1A may be supported by the wheels 1w (see FIG. 3) rolling on the deck. Although not shown, in place of such rotation of the furnace ceiling 1A, even if the furnace body is continuously rotated or rocked, the powdery and granular material is supplied during the operation of the furnace to obtain a uniform distribution in the furnace. Can be achieved.
Needless to say, this rotation of the furnace body or furnace roof can be easily realized in a small DC electric furnace that melts incinerated ash or the like that does not have a large throughput.

The operation control of a normal DC electric furnace is simpler than that of AC, but the range of the arc is localized as in the case of the single-phase AC electric furnace. In the present electric furnace using the L-shaped electrode, the controllability of the operation in the normal DC electric furnace is improved, and the electric power supply that covers a wide area from the hearth is improved by adopting the L-shaped electrode. It is understood that it has an extremely excellent point in terms of the function that a uniform melting process is realized inside.

By the way, when the raw material contains sewage sludge dry powder, a malodor may be generated when heated in the furnace due to the presence of the proteinaceous substance in the dry powder. Even in the case of incinerated ash, CO gas generated in the melting process of the raw material exists in the space above the deposited raw material.
In order to burn the offensive odor and unburned gas, a proper number of air introduction pipes 39 are radially installed in the upper portion of the furnace body shown in FIG. When a pressure draft is generated due to the temperature rise in the furnace, the outside air is sucked in, and it becomes possible to remove the odor by spontaneous combustion and burn CO. Of course, if the auxiliary burner 40 shown by the phantom line is arranged, its combustion is further promoted. The auxiliary burner 40 is designed so that the flame faces the outlet of the air inlet tube 39 and is tangential to the circular furnace body, which promotes the generation of a swirl flow to improve combustion efficiency and increase the efficiency of combustion. It can also contribute to the preheating of the raw materials that are contained. The auxiliary burner increases the energy supply,
Since it is a degree to burn unburned gas, it is an amount that can be ignored as a whole. On the contrary, as described above, the preheating of the raw material saves power consumption and also reduces the power consumption. The exhaust gas is sent to the dust collector and the like from around the movable electrode 1B through the smoke exhaust hood 41.

[Brief description of drawings]

FIG. 1 is an overall view of an artificial aggregate production facility for concrete that produces granular slag by producing granular slag from incineration ash or the like.

FIG. 2 is a plan layout view when two rotary furnaces for heat treatment are provided.

FIG. 3 is a schematic configuration diagram of a DC electric melting furnace and auxiliary equipment used in an artificial aggregate manufacturing facility.

FIG. 4 is an overall view of an artificial aggregate production facility for concrete that produces gravel-like slag by producing gravel-like slag from incineration ash and the like.

5A is an enlarged cross-sectional view of the L-shaped electrode, and FIG. 5B is a view taken along the line VV in FIG.

FIG. 6 is a plan view of a furnace ceiling as seen from the direction of an arrow.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electric melting furnace, 2 ... Granular slag forming device, 2A ... Slag receiving gutter, 2C ... Rotating drum, 2D ... Drum cooler, 2E
... Preheating sand feeder, 3 ... Rotary heat treatment furnace, 3A ... Rotary furnace body, 3B ... Heating burner, 3a ... Fire wall, 4 ... Raw material (incineration ash, etc.), 5 ... Molten pig iron, 6 ... Molten slag, 7 ... Granular slag, 7A, 7B ... Granular aggregate, 8 ... Preheated sand, 10 ... Hot screen, 14 ... Granular slag heat transfer device, 14A
... plate conveyor, 14B ... sand bed, 15 ... bed sand.

Claims (5)

(57) [Claims] 1. A method for producing an artificial aggregate for concrete from slag obtained by melting incinerated ash of garbage, dried powder of sewage sludge, etc., by reducing and melting incinerated ash containing coke breeze by a submerged arc electric melting method. In addition to reducing metal oxides such as Fe, Cr, P, etc. in incineration ash, which are easily reduced, to produce molten pig iron, molten slag having a low gas content and containing SiO ₂ as a main component is added to the molten pig iron. When it is generated in the upper layer and the molten slag is slagged every 2 to 3 hours, it is extracted in a short time in order to suppress heat dissipation from the molten slag and immediately rolled while contacting the water cooling wall. The molten slag is granulated, and the sand that has been preheated to a high temperature is coated to prevent quenching of the molten slag particles, and the mixed slag whose surface has solidified is sieved to remove the mixed sand. In addition, the granular slag is accumulated in the furnace while the temperature is not lowered to 800 ° C. or lower, and the granular slag is placed in a temperature atmosphere of 800 ° C. to 900 ° C. for 3 to 4 hours to obtain a structure with an extremely low gas content. A method for producing a granular artificial aggregate for concrete, which comprises producing a slag that is densely crystallized. 2. An apparatus for producing an artificial aggregate for concrete from slag obtained by melting incineration ash of refuse, dried powder of sewage sludge, etc., and melting easily reducible metal oxide from incineration ash etc. containing coke breeze. An electric melting furnace that generates molten pig iron by reducing and generates molten slag that does not contain the metal component, and a slag that receives molten slag that has been slagged in a short time to suppress heat dissipation from the electric melting furnace. To produce a granular slag whose surface is solidified by repeating rolling by rising and falling while cooling the gutter and the molten slag through a water-cooled iron shell, and to move the granular slag in the axial direction in the drum. The rotary drum inclined downward, the drum cooler for spraying the cooling water on the outer surface of the rotary drum, and the high temperature in the granular slag moving in the discharge direction in the rotary drum A granular slag forming device having a preheated sand feeder for mixing preheated sand, a hot screen for receiving high temperature granular slag discharged from the granular slag forming device together with the preheated sand and sieving off mixed sand, and the hot screen A rotary furnace body into which high-temperature granular slag from is introduced from one end opening, and a heating burner that heats the lining refractory wall of the rotary furnace body and the surface layer of the deposited slag. The granular slag whose outer shell is amorphized by the heating effect of the refractory wall that wraps around the slag and the reheat effect from the molten part in the slag is heat-treated to obtain a dense structure with an extremely low gas content. A granular heat treatment furnace for producing slag that has been crystallized, and a granular artificial body for concrete characterized by producing granular aggregate close to natural stone from molten slag such as incineration ash Wood manufacturing equipment. 3. In place of the rotary heat treatment furnace, high-temperature granular slag from the hot screen is charged from the upper end opening, and the outer shell is amorphized by the reheat effect from the molten portion in the slag. A vertical shaft furnace for heat-treating granular slag, which produces a slag in which a structure having an extremely low gas content is densely crystallized, is used for the concrete according to claim 2. Granular artificial aggregate manufacturing equipment. 4. An apparatus for producing an artificial aggregate for concrete from slag obtained by melting incineration ash of garbage, dried powder of sewage sludge, etc., and melting easily reducible metal oxides from incineration ash containing coke breeze. An electric melting furnace that generates molten pig iron by reducing and generates molten slag that does not contain the metal component, and a slag that receives molten slag that has been slagged in a short time to suppress heat dissipation from the electric melting furnace. To produce a granular slag whose surface is solidified by repeating rolling by rising and falling while cooling the gutter and the molten slag through a water-cooled iron shell, and to move the granular slag in the axial direction in the drum. The rotary drum inclined downward, the drum cooler for spraying the cooling water on the outer surface of the rotary drum, and the high temperature in the granular slag moving in the discharge direction in the rotary drum Granular slag molding apparatus having a preheated sand feeder for mixing preheated sand, a plate conveyor for receiving and transporting high temperature granular slag discharged from the granular slag molding apparatus together with the preheated sand, and a high temperature on the plate conveyor. Granular slag heat-insulating transfer device having a sand laying machine for laying down preheated sand, and a hot screen for sieving out mixed sand by receiving high temperature slag from the plate conveyor together with preheated sand or bedding sand. A rotary furnace body into which high-temperature granular slag from the hot screen is charged from one end opening; and a heating burner for heating a lining refractory wall of the rotary furnace body and a surface layer of the deposited slag. The granular slag whose outer shell is amorphized by the heating effect of the refractory wall that has circulated below the accumulated slag due to the rotation of the To produce granular aggregate close to natural stone from molten slag such as incinerated ash, which is equipped with a rotary heat treatment furnace that produces slag that has been processed to produce dense crystallization of a structure with extremely low gas content. An apparatus for producing granular artificial aggregate for concrete, characterized by: 5. In place of the rotary heat treatment furnace, high temperature granular slag from the hot screen is charged from the upper end opening, and the outer shell is amorphized by the reheat effect from the molten portion in the slag. A vertical shaft furnace for heat-treating the granular slag, which produces a slag in which a structure having an extremely low gas content is densely crystallized, is used. Granular artificial aggregate manufacturing equipment.