JPS6345857B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for producing granular lumps mainly used in metal refining using aluminum dross.

When aluminum is smelted or recycled and melted, aluminum dross (also referred to as aluminum residual ash) consisting mainly of aluminum oxide is generated.

Of this aluminum dross, the metal aluminum contained in the residual ash, which has a relatively large particle size, can be reprocessed and recovered as aluminum ingot for effective use. Although various studies have been conducted on powdered aluminum dross, it is still not possible to utilize it effectively, so the reality is that it is disposed of as industrial waste.

For example, research is being conducted on the effective use of finely powdered aluminum dross as a slag forming agent for steelmaking. If this is realized, it will meet the purpose of reduction in smelting work, greatly improve the yield of aluminum, and make it possible to utilize resources more effectively. However, if this fine powdered aluminum dross is directly put into a metallurgical reaction vessel as a slag forming agent, the fine powder of aluminum dross will be scattered by the high temperature turbulence caused by the molten metal inside the vessel and easily reach the surface of the molten metal. Not only does it not work, but even if some of this fine powder reaches the surface of the molten metal, it reacts instantly as soon as it reaches the surface of the molten metal, so it is hardly effective as a slag-forming agent. Moreover, since this aluminum dross is in the form of a fine powder, handling thereof is extremely inconvenient and significantly impedes work efficiency.

Therefore, research has recently been carried out on granulating finely powdered aluminum dross to an appropriate size. For example, a method has been proposed in which aluminum dross is granulated with a pan-type granulator and then fired at high temperature to decompose aluminum nitride, but this method has extremely poor granule strength and stability of granule shape. Therefore, the shape may collapse during transportation, the granulation cost is extremely high as it is not suitable for continuous mass production, and a large amount of ammonia gas is generated inside the granulator, causing pollution. Currently, it has various drawbacks and has not yet been put into practical use.

Therefore, most of the aluminum dross generated during aluminum refining is disposed of as is. However, dumping aluminum dross not only wastes valuable resources, but also causes secondary pollution as the large amount of aluminum nitride contained in the residual ash chemically reacts with rainwater and generates ammonia gas. Moreover, the dumping sites are limited, it is difficult to secure a dumping site, and furthermore, if the waste treatment is outsourced to a company, the cost will be extremely high.

Therefore, the effective use of aluminum dross is considered to be an important issue for this industry, which could affect the survival of the aluminum smelting business.

The present invention eliminates the above-mentioned conventional drawbacks, makes it possible to compress and solidify aluminum dross to produce granular lumps suitable for slag forming agents, etc., and realizes continuous mass production and pollution-free production. The object of the present invention is to provide an innovative method for producing aluminum granules and an apparatus for the same.

An embodiment of the present invention will be described based on the flow sheet shown in FIG. 1. 1 is an electric chain block;
2 is a raw material transporter for transporting fine powdered aluminum dross (raw material); 3 is a raw material hopper; 4
is a conveyor belt. 5 is a liquid binder storage tank, and 6 is a metering pump for continuously feeding a fixed amount of the liquid binder in the tank 5. Reference numeral 7 denotes a kneading machine for mixing and kneading the raw material continuously conveyed in a fixed amount by the belt conveyor 4 and the liquid binder fed from the tank 5; As shown in FIGS. 2 and 3, there is a pivot 8 which is rotationally driven by a motor, a pair of left and right wrought metal plates 9, 10 attached to the pivot 8, and a kneaded material attached to the pivot 8 side. It includes an extrusion scraping plate 11 and a kneaded material delivery port 12 that projects in a tangential direction to the circumferential inner wall surface 13 of the kneader main body. 14 is a quantitative feeder attached to a feeder chute 15 connected to the kneaded material outlet 12 of the kneading machine 7;
Reference numeral 4 is for continuously feeding a certain amount of the kneaded material sent out from the kneader 7 into the granulator.

Reference numeral 16 denotes a granulator for granulating the kneaded material sent through the feeder chute 15 into pellets; the granulator 16 granulates the kneaded material charged into the machine. It compresses and molds it into a pellet shape, and its specific structure is one that directly adopts known granulator technology such as a piston extrusion molding mechanism or a die molding mechanism. The specific structure of 16 is not limited.

24 is a pellet conveying chute connected to the granulator 16.

Reference numeral 25 denotes a pellet dryer for drying the pellets sent from the granulator 16 through the chute 24, and the pellet dryer 25 includes a drying furnace 26 having a high-temperature hot air chamber 27 in the furnace. From the heat-resistant mesh conveyor belt 28 of the belt conveyor 51 that passes through this high-temperature hot air chamber 27 and runs in a predetermined direction, the motor 29 for driving and running the belt 28, and the large number of belt tensioning rollers 30. A hopper 31 for non-standard products and a storage container 32 for non-standard products are provided below the belt 28 in the pellet discharging direction of the chute 24.
A product storage container 33 is provided below the feed end.

Next, the circulation system of high-temperature hot air to be sent to the pellet dryer 25 will be explained.
35 is an oil tank for storing heavy oil, etc.; 35 is a pump for discharging the heavy oil, etc. in the oil tank 34; 36
3 is a flow meter unit attached to the fuel supply path 37;
8 is a burner connected to the fuel supply path 37.
39 is a combustion furnace for generating high-temperature hot air in the furnace through combustion by the burner 38. 4
0 is a thermometer attached to the combustion furnace 39, 41 is a high-temperature hot air supply path connected to the combustion furnace 39, and 42 is a blower for forcedly feeding hot air attached to the high-temperature hot air supply furnace 41. and the high temperature hot air supply path 4
1 is connected to the high-temperature hot air chamber 27 of the pellet dryer 25, and is configured so that a large amount of high-temperature hot air can be sent into the chamber of the pellet dryer 25. 43 is a discharge path for discharging the hot air that has passed through the interior of the pellet dryer 25; 44 is a blower for circulating exhaust air attached to the discharge path 43; and 45 is the hot air sent through the discharge path 43. This is a cyclone separator that separates the exhausted exhaust gas from fine particles that may be mixed in the exhaust gas. In addition, the discharge path 43 connected to the cyclone separator 45
is connected to the combustion furnace 39 and the high temperature hot air supply path 41 in a branched manner.

In the above configuration, when operating the production apparatus according to the present invention to produce granular lumps using aluminum dross, first, the electric chain block 1 is operated to move the raw material transporter 2 to transport the raw material hopper 3. The aluminum dross (raw material) in the form of fine powder contained in the raw material transporter 2 is charged into the raw material hopper 3. The raw materials in the raw material hopper 3 fall sequentially from the bottom of the hopper onto the belt conveyor 4 in fixed quantities, so after being transferred in a predetermined direction by the movable belt conveyor 4, they fall into the kneading machine 7 whose top end is open. . The amount of raw material supplied by this belt conveyor 4 is preferably about 500 kg/hr.

On the other hand, the liquid binder stored in the liquid binder storage tank 5 is injected into the kneading machine 7 from the nozzle 47 through the liquid binder supply path 46 by the metering pump 6. The feed rate of this liquid binder is preferably about 100/Hr.

Inside the kneading machine 7 into which the raw materials and liquid binder are fed simultaneously, a pair of kneading plates 9 and 10 are rotated integrally with a pivot shaft 8 that is rotationally driven by a motor. Therefore, the raw material and the liquid binder are uniformly mixed and kneaded by the double kneading plywood plates 9 and 10 to form a kneaded product.

An example of the analysis of the components of the raw material, fine powder aluminum dross of 60 mesh or less, shows that aluminum oxide is 74%, aluminum metal is 6%
%, Igross 11%, and others 9%, including aluminum nitride. Further, as the liquid binder, water or an aqueous solution containing water glass or the like is used. Incidentally, the aluminum dross used as a raw material is not limited to a fine powder of 60 meshes or less, but dross of 60 meshes or more can of course be used. Further, the mixing ratio of the dross raw material and the liquid binder is determined depending on the properties of the dross.

The kneaded material mixed and kneaded in the kneader 7 is
The kneaded material is scraped off by the kneaded material extrusion scraping plate 11 which is rotated by the rotation of the pivot 8, and the kneaded material is removed from the kneaded material outlet portion 12.
is sent out of the aircraft through the Thereafter, while the kneaded material is being fed through the feeder chute 15, the amount of kneaded material to be transferred is kept constant by the metering feeder 14, and the kneaded material is continuously fed into the granulator 16 in fixed amounts.

Inside the granulator 16, into which the kneaded material is charged from the upper end opening, the kneaded material is extruded and granulated continuously in a pressurized and compressed state. Each pellet is continuously discharged to the outside of the machine as a single pellet.

Each pellet leaving the granulator 16 falls onto the starting end of a conveyor belt 28 via a pellet conveying chute 24. In this state, since the belt 28 has a heat-resistant mesh structure, small pellets of non-standard size mixed in the pellet group fall through the mesh of the belt 28,
The non-standard product storage container 3 is connected to the non-standard product storage container 3 via the non-standard product hopper 31.
It is stored in 2.

On the other hand, standard products have a running conveyor belt 28
The pellets placed on the pellet dryer 25 enter the inside of the furnace high temperature hot air chamber 27 and the conveyor belt 2
As each pellet advances as it moves by the belt 8, it dries and solidifies while passing through the high-temperature hot air chamber 27 in the furnace, so that the pellets leaving the dryer 25 remain in a solid state until they reach the feed end of the belt 28. The product falls and is stored inside the product storage container 33.

After the aluminum nitride and water in the aluminum dross are combined in the kneader 7, the kneaded product is granulated into pellets in the granulator 16 and sent to the high temperature hot air chamber 27 in the pellet dryer 25. It is necessary to perform the steps up to entry as quickly as possible, and the time required for the above steps is at least 20 minutes, preferably within 5 minutes to complete the series of steps.

This is because when fine powdered aluminum dross and liquid binder are kneaded, a chemical reaction gradually occurs and reaction heat is generated, and at the same time, ammonia gas is generated and the kneaded material itself gradually solidifies. It is. Therefore, the kneading process, granulation process, etc. must be completed before reaction heat is generated from the kneaded material and the self-solidification phenomenon is completed.

To explain the operation of the pellet dryer 25, the fuel sent out from the oil tank 34 by the operation of the pump 35 is sent through the fuel supply path 37 and is combusted by the burner 38. High-temperature hot air is generated, and is sent through the high-temperature hot-air supply path 41 into the high-temperature hot-air chamber 27 in the furnace of the pellet dryer 25 by the operation of the blower 42, thereby heating the inside of the furnace.

The gas that has circulated through the high-temperature hot air chamber 27 in the furnace is discharged through the exhaust passage 43 by the operation of the blower 44 and sent to the cyclone separator 45 .
The amount of exhaust gas sent to the blower 44 is adjusted by a valve 49 that is automatically adjusted based on a command from a thermometer 48 attached to the drying oven 26.
The cyclone separator 45 separates the exhaust gas from particulates mixed in the gas, and only the exhaust gas is sent out through the exhaust path 43, and if the exhaust gas maintains a high temperature state, it is circulated to the high temperature hot air supply path 41. However, if the exhaust gas is at a low temperature, the combustion furnace 39
After being combusted again, the high-temperature hot air supply path 4
Send it to 1. Note that the exhaust gas discharged from the drying furnace 26 contains a large amount of ammonia gas generated from each pellet on the conveyor belt 28, so when this exhaust gas is sent to the combustion furnace 39, the ammonia gas is combusted. A part of the high-temperature gas is released to the outside through the exhaust passage 50, but the remaining high-temperature gas is circulated and reused as a heat source for the drying oven.

The mixing ratio of the aluminum dross raw material and the liquid binder supplied into the kneading machine 7 is not specifically limited, but as a result of experiments, it was found that the mixing ratio of the liquid binder to 5 raw materials is 1 part. It was possible to produce the most desirable granular mass. Therefore, considering the material balance, if 500 Kg/Hr of raw materials and 100 Kg/Hr of liquid binder are fed into the kneader 7 at the same time, 600 Kg/Hr of kneaded material can be produced in the kneader 7. However, if the kneaded material is granulated and then transferred to the drying process, 88.2Kg/Hr of the moisture contained in the compressed and solidified aluminum granules will evaporate in the drying process, and the product will be shipped to 511.8Kg/Hr. It was possible to produce continuously.

According to the method for producing granular lumps and the apparatus for producing the same according to the present invention, the following excellent effects are significantly exhibited.

a. Conventionally, it was thought that it could not be used effectively60
We succeeded in compressing and solidifying aluminum dross, which is in the form of a fine powder smaller than a mesh, to produce strong granular lumps, which makes it possible to effectively use it as a slag-forming agent for metal refining, for example. Therefore, not only was it possible to recycle resources, but it also eliminated difficult problems such as secondary pollution caused by the disposal of dross and securing a dumping site.

b) Aluminum dross raw material and liquid binder are simultaneously fed into a kneading machine at a predetermined ratio, thoroughly mixed and kneaded, and then pressure-extruded into a granulator to form compressed pellets. Since the product is sent into an instant drying oven and solidified, the granule strength and stability of the granule shape of the granular agglomerate product are extremely excellent.

c In particular, the raw material and the liquid binder are mixed and kneaded in a kneader to form a kneaded state with a uniform structure, and this kneaded product is compressed and molded by pressurizing and extrusion molding in a granulator. The pellets are solidified in a drying oven due to self-heating of the pellets (a phenomenon in which aluminum nitride in the pellets and water in the liquid binder combine to cause a chemical reaction and generate reaction heat). and a solidification phenomenon that occurs by evaporating the moisture contained in the pellets by high-temperature hot air drying. Therefore, both of the solidification phenomena described above can synergistically produce extremely strong granular lumps. I can do it.

d Moreover, the series of processes from the kneading process of the raw material and liquid binder in the kneader to the granulation process of the kneaded material in the granulator and just before moving on to the drying process are performed by combining the raw material and the liquid binder. It generates reaction heat and ends the self-solidification phenomenon before it is completed. Therefore, during the series of steps in which raw materials and liquid binder are kneaded and granulated, the pellets themselves still generate reaction heat and the self-individuation phenomenon has not yet been completed, leading to a transition to the drying process. Ammonia gas is also generated at the same time as self-heating solidification and high-temperature hot air drying until passing through the high-temperature hot air chamber, and granulation solidification is completed, so a series of process operations such as kneading and granulation processes can be carried out smoothly. This enables continuous operation and mass production, and minimizes the causes of failure.

e The granular lumps produced by the production method and production apparatus of the present invention are compressed and solidified to a high density as described above, and therefore have extremely excellent granule strength and stability of granule shape. Therefore, the shape of the granular lumps does not collapse even during transportation and handling operations, and storage and handling operations are easy. Even if the granules are poured into the molten metal, they will not cause problems such as scattering or rapid reaction on the surface of the molten metal, and will surely reach the inside of the molten metal and mix in. The granular agglomerates gradually undergo an oxidation reaction to deoxidize the molten material such as metal. Therefore, it has high efficiency as a slag-forming agent and also meets the purpose of reduction in refining operations.

f According to the manufacturing apparatus according to the present invention, continuous mass production of granular lumps is possible. That is, a kneading machine that is equipped with a continuous quantitative supply means for aluminum dross and a continuous quantitative supply means for a liquid binder and that kneads raw materials and a liquid binder, and a granulation machine that compresses and shapes the kneaded material continuously sent from the kneading machine. The machine is equipped with a dryer that sends the pellets sent out from the granulator to a high-temperature hot air chamber and automatically sends them on a belt conveyor, so aluminum granules can be manufactured continuously and mass production can be realized. It is something. Therefore, by continuous mass production of granular agglomerates, it is possible to save labor and manpower, and to promote a large cost reduction.

g The granulated pellets self-heat and dry at high temperatures in the drying furnace to generate ammonia gas, so this ammonia gas is sent to the combustion furnace together with the furnace exhaust gas and burned, and the high temperature generated in this combustion furnace is Circulating hot air is effective in eliminating pollution and conserving thermal energy.

[Brief explanation of drawings]

FIG. 1 is a flow sheet of the entire apparatus showing one embodiment of the present invention, and FIGS. 2 and 3 are a plan view and a front view of the mixer. 2 is a raw material transporter, 4 is a belt conveyor, 5 is a liquid binder storage tank, 6 is a metering pump, 7 is a kneading machine, 15 is a feeder chute, 16 is a granulator, 24 is a pellet conveying chute, 25 is a pellet Dryer, 26 is a drying oven, 27 is a high temperature hot air chamber,
28 is a conveyor belt, 34 is an oil tank, 38 is a burner, 39 is a combustion furnace, and 51 is a belt conveyor.

Claims (1)

[Scope of Claims] 1. Knead aluminum dross and a liquid binder that are continuously supplied in fixed quantities, compress and mold the kneaded material to form pellets, and heat the pellets in a dryer at a high temperature in a furnace. The pellets are dried by passing through a hot air chamber, and the series of steps from the end of the kneading and granulation steps to just before the drying step is completed before the pellets generate reaction heat and the self-solidification phenomenon is completed. A method for producing granular lumps using aluminum dross. 2. The method for producing granular lumps using aluminum dross according to claim 1, wherein the aluminum dross is in the form of a fine powder of 60 mesh or less. 3. The method for producing granular lumps using aluminum dross according to claim 1, wherein the liquid binder is an aqueous solution containing water vitreous. 4. A continuous quantitative supply means for aluminum dross, a continuous quantitative supply means for a liquid binder, a kneader for kneading the dross raw material and the liquid binder, and a structure for compressing the kneaded material continuously delivered from the kneading machine and forming it into pellets. A method for producing granular lumps using aluminum dross, which is equipped with a granulator and a dryer that sends the pellets sent out from the granulator into a high-temperature hot air chamber and automatically feeds them on a belt conveyor that runs inside the furnace. Manufacturing equipment. 5. The apparatus for producing granular lumps using aluminum dross according to claim 4, wherein the belt of the conveyor that runs in the oven of the dryer has a heat-resistant mesh shape.