JPS6357731A - Treatment of aluminum swarf or the like - Google Patents

Abstract

PURPOSE:To recover Al industrially with low energy at a high yield by subjecting Al swarf (turnings), etc., to a heating and dry distillation treatment under anaerobic conditions by using a dry distillation furnace. CONSTITUTION:The raw material turnings are supplied into the dry distillation furnace 3 which is provided with agitators such as agitating vanes and in which an anaerobic state, i.e., oxygen starvation state is maintained by hermetic sealing. Fuel, air or oxygen is supplied into the furnace 3 only in the beginning to maintain and control the temp. in the furnace 3 to and at an adequate temp.; thereafter, the oxygen concn. is controlled with the absence of fuel supply and evaporatable and combustible matters are burned to maintain the adequate temp. While the turnings in the furnace 3 are agitated by the vanes 5, the turnings move and the oils and moisture sticking thereto are gasified. The air is supplied under control to the furnace 3 to maintain the temp. and to cause partial combustion of part of the produced gas, by which the turnings are cleaned. The high-quality clean turnings contg. decreased oxides are delivered from a taking-out pipe 23 to a melting furnace 25 where the turnings are melted by the conventional method.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for processing aluminum cutting waste, etc., and contributes to the recovery of aluminum resources, and is not only used extensively in the aluminum industry. It also makes a significant contribution to the effective use of waste aluminum foil, beautification of the environment, and prevention of pollution.

[Conventional technology]

Shredder scraps, aluminum foil scraps, and the like are melted and recycled as aluminum cutting scraps or recovered aluminum scraps called die powder generated in the manufacturing process of aluminum or aluminum products.

However, water, oil, and other impurities are attached to or mixed with the powder, so if the powder is directly sent to the melting furnace and melted without any treatment, the melting yield will be low, and the molten metal will not be charged. This is not normally done due to the deterioration of the working environment due to explosive combustion.

Therefore, in order to remove these impurities prior to melting in a melting furnace, the conventional method is to heat the powder directly with a burner flame in a rotary kiln at a high temperature of about 600 to 800 degrees Celsius. is the current situation,
It is possible to use a completely sealed continuous process carbonization furnace as in the present invention, to control the supplied oxygen concentration under anaerobic conditions, and to maintain the optimum temperature through partial combustion to carry out the heating carbonization process, or by rotating the entire furnace. A system in which treated aluminum cuttings and the like are stirred using a stirring device inside the furnace has not been known in the past, and is completely unknown.

[Purpose of the invention]

As mentioned above, in the conventional high heat treatment method using a rotary kiln, the oxide film on the surface of the layer during treatment becomes thick, which not only results in a poor yield of recovered aluminum metal after melting, but also causes the rotary kiln to become open. Because of the type, the amount of exhaust gas is large, and the reburning process requires a large amount of fuel, and the exhaust gas treatment is also large-scale.In other words, it requires a very large amount of energy, which is a major drawback that can be called fatal from an industrial perspective. is unavoidable.

The present invention was made in view of the current state of technology, and is excellent in recovering aluminum. This was done for the purpose of developing a new energy-saving industrial treatment method.

[Disclosure of the invention]

The present invention has been made to achieve the above object,
As a result of thorough research on the mechanism of aluminum recovery from Dalai powder, as well as research on the effective use of exhaust gas and the organic bonding of each element, from a chemical industry perspective,
I learned that I could not achieve my desired goal using conventionally known methods, and realized that I needed to change my way of thinking.

As a result of thorough research, we found that the reason for the decrease in aluminum recovery yield was that the aluminum was oxidized due to the high temperature treatment of the powder in an open rotary kiln under aerobic conditions. Ta. Based on this knowledge, we investigated various aspects of industrial heat treatment under anaerobic conditions, and as a result, we focused on the use of a carbonization furnace. After repeated experiments, it was discovered that using a carbonization furnace allows heat treatment to be performed at much lower temperatures than when using a conventional rotary kiln, and also significantly increases the yield. .

In order to make the carbonization furnace work even more effectively, we tried various methods to agitate the inside of the furnace using a stirring device.
While the conventional method had a melting yield of only about 92%, this was a great industrial achievement in that it achieved a melting yield of over 95%, and the conventional method required high-temperature heat treatment of over 800°C. On the other hand, we have confirmed a new and useful finding that the above-mentioned high yield can be obtained at a low temperature of about 400° C., which is about half that of the conventional method. As a result, it was also confirmed that fuel consumption could be greatly reduced, and the present invention was completed.

The raw material to be processed in the present invention is aluminum cutting waste, etc., which includes aluminum waste, cutting waste, shredder waste, etc. generated during the manufacturing of aluminum products, and
All aluminum-containing materials are included, such as the used layer of aluminum products such as used aluminum cans.

The invention will now be described in detail with reference to the accompanying drawings and with reference to an apparatus for carrying out the invention.

Pre-pulverized raw material dry powder adhering to oil and moisture is supplied to a hopper 1, and is supplied from a screw feeder 2 into a carbonization furnace 3 through a sealed raw material supply port. A stirring device is provided in the carbonization furnace 3, but in this embodiment, a rotating shaft 4 is provided.
is passed through the carbonization furnace main body, and a plurality of stirring blades 5 are attached to the rotating shaft 4, which stirs the flour as the shaft rotates to ensure uniform heating.
It is rotated by a variable speed motor M via a conduction bag @6. The rotation speed depends on the type and particle size of the powder used as processing raw material,
Although it varies depending on the degree of contamination, it is preferable to set the speed to about 8 rpm. Although the stirring blades are rotated in this embodiment, a known stirring device such as a one-screw type stirring device may be used as appropriate.

The inside of the carbonization furnace 3 is completely sealed and kept in an anaerobic state, that is, an oxygen-deficient atmosphere.

Therefore, openings, shaft penetrations, etc. should be filled with airtight valves,
Seal tightly with an airtight opening/closing cover, airtight seal, etc.

Inside the furnace 3, heavy oil, other fuel, and air (or oxygen) are supplied from the supply lower through the pipe 8.9 only at the beginning to cause combustion, and the temperature inside the furnace is maintained and controlled at about 300 to 500°C. After that, the evaporated combustibles are combusted by controlling the oxygen concentration without supplying fuel, and the temperature is maintained.

The flour in the furnace is moved while being stirred by stirring blades, and the oil and moisture attached to it are gasified. In order to maintain the temperature inside the furnace, air is added from the supply lower while being controlled, and a part of the generated gas is partially combusted. By anaerobic heating, not only small amounts of oil and water adhering to the flour but also large amounts of oil such as paint printed on aluminum cans are sufficiently and efficiently gasified and the flour is cleaned.

Most of the gas generated in this way is at the gas outlet 1.
0 and is discharged from the furnace. Since this is a combustible gas, this embodiment has a configuration in which it is treated in a reburning furnace 12 via a pipe 11 from the viewpoints of effective use of energy, effective use of gas components, and prevention of air pollution.

In the reburning furnace 12, the generated gas is introduced and supplied into the furnace through a gas supply port 13, while a pipe 8.
Supply sufficient fuel and air from 9 to 800 to 1000
The generated gas is completely combusted at a temperature of about ℃, and the oil becomes CO□
It is oxidized to H, O, etc., completely treated, and deodorized at the same time. At this stage, the oil and water derived from the dalai powder are completely decomposed and deodorized and become harmless, so it can be released into the atmosphere as is, but it can also be subjected to further processing. .

That is, the gas generated in the reburning furnace is oxygen-poor gas, which is taken out from the exhaust port 15 and guided to the cooler 17 via the pipe 16. Water, air, and other fluids are supplied to the cooler 17 from a pipe 18, and are brought into contact with the above-mentioned high-temperature oxygen poor gas for heat exchange. Such fluids are heated to turn them into hot water, steam, etc.

The gas cooled by the above is passed through the pipe 19 and the exhaust fan 2.
0 into the atmosphere as it is, but the - part is discharged directly into the atmosphere through pipe 21. It is introduced into the dry powder take-out pipe 23 via the circulation fan 22 and pipe 27 and returned into the furnace 3. The cooling gas is rich in nitrogen and carbon dioxide gas and contains very little oxygen, and it retains a sufficient amount of heat, so by blowing it into the furnace, the exhaust powder is saturated. The dry powder is cleaned by washing away adhering oil and the like, but it also supplies a heat source to the inside of the furnace, and in this way it is possible to save on fuel consumption.

The dry powder treated in this way in the carbonization furnace 3 not only has impurities such as oil and moisture removed, but also has less oxide film compared to conventional methods, and as a result, the yield of aluminum products is greatly improved. Upload to. The high-quality cleaned powder with less oxides thus obtained is sent from the powder extraction pipe 23 to the melting furnace 25 via the screw feeder 24.
A high quality product 26 is obtained by dissolving this in a conventional manner.

Using the above-mentioned apparatus, 1 ton of raw material powder was treated under the following conditions. The temperature inside the carbonization furnace was 450°C, the stirring blade rotation speed was 8 rpm, the temperature inside the reburning furnace was 900°C, and the temperature of the oxygen poor gas from the cooler was 450°C. It was then treated in a melting furnace in a conventional manner to obtain a good quality product with a yield of 97%.

〔Effect of the invention〕

As described above, the present invention employs a new configuration in which dry distillation treatment is performed by heating dry powder under anaerobic conditions using a carbonization furnace.As a result, the heating temperature can be extremely lower than that of conventional methods, allowing aluminum to be heated and dry-distilled under anaerobic conditions. It is possible to efficiently remove oil and moisture without causing oxidation, resulting in a significant improvement in the yield of product aluminum.

Moreover, rather than releasing the exhaust gas directly from the carbonization furnace to the outside, the system organically combines the reburning process and the cooling process to make the exhaust gas harmless and then release it to the outside. In addition, since a part of it is returned to the carbonization furnace and its heat and anaerobic properties are reused, fuel consumption is further reduced and at the same time an effect of preventing air pollution is obtained. Although batch processing has been described, continuous processing can also be carried out freely by performing necessary valve operations.

Thus, according to the present invention, a very high yield can be obtained with much lower energy than in the prior art, and it can be seen that the present invention is particularly suitable for large-scale industrial processing. Furthermore, it can be easily understood that the present invention is extremely superior as a pollution prevention technology.

[Brief explanation of the drawing]

The drawings illustrate one example of an apparatus for carrying out the invention.

Claims (1)

[Claims] Aluminum cuttings, etc. are fed into a closed carbonization furnace equipped with a stirring device, and while stirring, the oxygen concentration is controlled and partially combusted, the temperature is maintained, and the heating process is carried out under anaerobic conditions. Characteristic method for processing aluminum cutting waste, etc.