JPS6137934A - Regenerating method of al from waste al can - Google Patents

Abstract

PURPOSE:To suppress Al oxidation and to improve regenerating yield, by cutting a waste Al can, decomposing and removing the coated film of organic compound by dry distillation, press forming said material and melting them by conventional method. CONSTITUTION:The waste Al can is dropped on a conveyer 2 from a hopper 1, and crushed by a crusher 4 after removing iron material therein by a primary magnetic separator 3. Crushed pieces are washed on a conveyer 5, then supplied to the first preheating hopper 8 and preheated after iron piece therein is removed on a conveyer 9 by the second magnetic separator 7. Next, said pieces are supplied to a dry distillation kiln 12 at a prescribed temp. by rotary valves 11 to heat them to about 400-500 deg.C by a combustion chamber 13, the organic coating material coated on the surface is decomposed thermally, most of them are converted to gas, and a part thereof is carbonized and removed from Al pieces. Next, said pieces are supplied to a quantitative supplying apparatus 17 in order by rotary valves 11, press formed by a pressing machine, and said material is supplied to a melting furnace through the second preheating hopper 19.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention is applied to aluminum (
The present invention relates to a method for recycling M from used cans made of (hereinafter abbreviated as Al) or defective products in the production process (gAl cans).

Conventional technology Conventionally, aluminum can be recycled from waste aluminum cans by removing iron cans from the collected waste cans by magnetic sorting, cutting the separated aluminum cans into small pieces, and cleaning them to remove foreign matter. After that, they are magnetically sorted again to remove ferrous metal pieces, and the two separated M cut pieces are placed in a combustion furnace where protective coatings and printed coatings formed on the surface are directly burned to remove them, and then melted. Melt in a crucible or with a protective coating or printed coating still on.

A common method is to cast it into an ingot.

Problems that the invention aims to solve The conventional method of delacquering involves roasting waste aluminum cans in a kiln, etc., but a large amount of money is required to treat the gas generated at this time.Especially in order to eliminate odor. This is done using the afterburning method, but since it contains air, there is a large amount of gas, and it is not easy to deal with it technically, which could lead to pollution problems. In addition, there is the disadvantage that a large amount of Al is oxidized at the same time during the combustion process and cannot be recovered, and there is also the problem that when the Al pieces are put into the melting crucible after combustion, the Al pieces are light and float on the surface of the molten metal, causing further oxidation. Ta. An object of the present invention is to provide a method for regenerating Al without such loss due to oxidation of Ad.

Means to solve the problem: Confusing the above problem, we stopped the direct combustion of the Al cut pieces and attempted carbonization while cutting off the air, but the coating film on the surface was thermally decomposed and vaporized, and most of it was removed from the surface. It is.

It was discovered that Al does not undergo oxidation at all.

In addition, the vaporized thermal decomposition products were recovered as flammable oils in the low-temperature zone of the carbonization furnace, and the components that were not liquefied were also flammable gases.

Next, when introducing the Al pieces into the Al melting crucible, the thickness of the Al is formed into a lump using a surface press.

The present invention was achieved by discovering that the larger the apparent density, the lower the loss due to oxidation of AiI.

Structure of the Invention According to the present invention, in a method for recycling Al from a waste Al can, in which an Al ingot is obtained by cutting a waste Al can, and then melting and casting the two sorted cut pieces, a carbonization step is provided prior to melting. Waste A cans characterized by decomposing and removing the coating film of organic compounds formed on the can surface, compressing the obtained Ann pieces using a press to make a pressed mass, and then dissolving it by a conventional method. A method for regenerating Al from is provided.

According to the present invention, there is also provided the above-mentioned method, characterized in that the gaseous products generated during the carbonization step are used as part of the fuel in the carbonization reservoir.

Although the carbonization temperature in the method of the present invention can be carbonized in a short time during the high temperature phase, a carbonization temperature of about 400 to 500 DEG C. is sufficient to thermally decompose the organic coating film on the Al can. The recovery of pyrolysis products using a carbonization button is the same type as that used in carbonization equipment for waste plastics and tires (for example, Japanese Patent Application Laid-Open No. 15447-1983).
7, JP-A No. 56-133432) can be used as is, and the problem of smoke, bad odor, and dust can be solved by recycling the recovered thermal decomposition product as fuel for the carbonization furnace.

In addition, when dissolving the Al piece after carbonization, the input sample should be as much as possible.
It is necessary to form lumps with as high an apparent density as possible so as not to float on the surface of the molten metal, and in order to achieve a recovery rate of 80 or more, the apparent density must be 1.0 or more.

Effects of the Invention The method of the present invention minimizes the amount of gas generated during carbonization, and at least completely burns the gas, so that no gas odor is released from the system, and the cost involved is also lower than that of conventional methods. It has become so cheap that it is not a problem at all. Also, Al
The oxidation of Al was significantly suppressed, and the recovery rate of Al was improved. The recycling of pyrolysis products not only eliminated the problems of smoke, odor, and dust, but also reduced energy costs.

Embodiment FIG. 1 shows a system of apparatus for carrying out the method of the invention.

The waste Al cans are dropped from the raw material hopper 1 onto the raw material conveyor 2, and then processed into iron products (such as tin cans) by the magnetic separator 3.
is removed, crushed into pieces, preferably about 5 cTt square, by a crusher, preferably a hammer crusher, and dropped onto a crushed piece conveyor 5, where it is washed with a cleaning spray and dropped onto a washed piece conveyor 9, The iron pieces are removed by a secondary magnetic separator 7 and dropped into a first preheating hopper 8. A rotary valve 11 is installed in the discharge pipe of the first preheating hopper.
is provided, and the carbonization vessel 12 is heated at a speed determined by the
supplied to

It has a jacket tube 13 on the outside, which forms a combustion chamber. A part of the exhaust gas is led to the jacket of the first heating hopper 8 by conduits 30, 31, and the other part is also sent to the jacket of the second heating hopper 19, which will be described in detail later, by conduits 30, 32. A valve lO is provided for its adjustment.

The combustion chamber 13 is provided with an oil burner 15 and a gas burner 16. Vibrations may be applied to the combustion pot 12 to facilitate movement of the Al crushed pieces to be treated. In any case, the Al crushed pieces 31 descend while being heated here, and are sequentially discharged by a rotary pulp 11' provided at the outlet, and are dropped into a quantitative supply device 7.

The heating temperature of the Al crushed pieces to be treated in the combustion chamber is 400~
At 500°C, the limit is 550°C. When the crushed Al pieces are heated in the absence of oxygen, the organic coating material applied to the surface is thermally decomposed, most of it turns into gas, some of it carbonizes, and the Al pieces are removed. be done.

The quantitative supply device is a belt conveyor with claws that scrapes out the Al pieces at a constant speed and supplies them to the press 18. Pubis machine is preferably "Biocube Press"
With this machine, the aluminum pieces are formed into 3 m cubes and sent by a cube conveyor 33 to a second preheating hopper 19, which in turn feeds the melting furnace.

The gas generated by the decomposition of organic paint materials is mainly hydrocarbon monomers, but also contains oily substances at room temperature and hydrochloric acid and water generated from chlorine-containing substances such as polyvinyl chloride. This carbonized gas is sent to a condensation tower (oil/water separator) 23 via a conduit 14. The condensing tower 23 has a jacket structure and is provided with an inlet 20 and an outlet 21 for cooling water. The carbonized gas is cooled here and separated into high boiling point, low fractionation gas and relatively low boiling point oily and aqueous substances.

Gas containing chlorinated ice cream gas etc. is sent to a gas purifier 26 through a conduit 22, where it is purified by being sprayed with an aqueous solution of caustic soda, and the aqueous portion is completely removed by a mist separator 29 before being sent to the gas burner 16. is sent to be burned.

On the other hand, the oily matter and aqueous matter separated in the condensing column 23 are sent to an oil-water separator 34, and the aqueous part is discarded.

The oil is transferred to the second oil tank where it is mixed with fresh fuel oil supplied from the first oil tank 28 and burned by the oil burner 15.

As described above, according to the method of the present invention, waste Al cans are continuously treated and the carbonized gas produced is recirculated and burned as part of the fuel, so it is extremely efficient and economical.

Al1! The recovery rate of Al during melting is related to the bulk specific gravity of the pressed mass of crushed Al pieces. This relationship determined through experiments is shown in FIG. According to this, there is an almost linear relationship between bulk specific gravity and recovery rate.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of an apparatus system for carrying out the method of the present invention. FIG. 2 shows the relationship between the bulk specific gravity of a pressed mass of crushed Al pieces and the dissolution recovery rate. In Figure 1

Claims (1)

[Claims] 1. In a method for recycling Al from a waste Al can, in which after cutting a waste Al can, the sorted cut pieces are melted and cast to obtain an Al ingot, a carbonization step is provided prior to melting. Al
Al from waste Al cans, which is characterized by decomposing and removing the organic compound coating formed on the can surface, compressing the obtained Al pieces using a press to form a pressed mass, and then dissolving it by a conventional method. regeneration method. 2. After cutting a waste Al can, the selected cut pieces are melted and cast to obtain an Al ingot. In a method for recycling Al from a waste Al can, a carbonization step is provided prior to melting to remove Al.
The organic compound coating formed on the can surface is decomposed and removed, the resulting Al pieces are compression-molded using a press to form a pressed mass, and then melted using a conventional method, and the decomposition products obtained in the carbonization process are carbonized. A method characterized in that it is used as a fuel in a process.