JP2019183275A - Melting method and melting unit of aluminum chip - Google Patents

Abstract

To provide a melting method and a melting unit of aluminum chips getting aluminum melt by melting chips which are cutting scraps of aluminum metal or alloy.SOLUTION: A melting method of aluminum chips includes: a pre-heating step for removing oily water in adhering cutting oil of the aluminum chips by evaporation or decomposition; a charge step and a melting step that the preheated chips are charged into aluminum melt, spreaded and melt; and a gas processing step for combusting the decomposition gas or evaporation gas of the cutting oil generated in the pre-heating step to eliminate pollution. An oil-water separation step and a sizing step are arranged before the pre-heating step. A melting unit is provided in which the chips are mixed and stirred to melt in a chip surfacing prevention area provided in a fusion furnace.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method and apparatus for melting aluminum chips, and more particularly, to produce molten aluminum having good quality and high yield in melting aluminum metal or alloy chips to obtain molten aluminum. In addition, the present invention relates to a method and an apparatus for melting aluminum chips that are safe and can achieve energy-saving operation while paying attention to environmental conservation.

  Since aluminum metal requires a large amount of electric power during its production, its production cost is high. Therefore, as long as scrap and scrap generated when processing into an aluminum product take the form of aluminum metal, the value is great in consideration of the manufacturing cost. Therefore, it is usual to recycle and melt aluminum scraps, cans and the like to obtain molten aluminum, and then to make aluminum products, and aluminum metal cutting scraps, so-called aluminum chips, are similarly treated.

  It is desirable from the viewpoint of resource saving and energy saving that the aluminum chips are remelted and recycled as aluminum. For this reason, it is desirable from the viewpoint of environmental conservation such as the quality of the molten aluminum and the prevention of smoke generation during production that the cutting oil adhering to the chips is removed by heating and evaporation before the chips are dissolved. As an example, after removing aluminum chips with cutting oil remaining in a rotary kiln by calcining so that aluminum is not oxidized and volatilizing oil and moisture, the aluminum chips are made into briquettes and dissolved in aluminum There are some which obtain molten aluminum by charging into a furnace. The volatilized oil is burned in a reburning furnace and diffused to the atmosphere through a dust collector. This equipment is good in that aluminum chips can be reused, but the equipment requires a large variety of equipment, etc., and when it is dried and calcined, it is used in dust collectors and ducts with aluminum dust generated from the rotary kiln. There were problems such as the risk of ignition and explosion.

  In order to solve the above-mentioned problems, aluminum chips accompanied by water-containing cutting oil are pretreated to remove moisture in the cutting oil, leaving only the oil, and then melted in an aluminum melting furnace to obtain molten aluminum. At the same time, an aluminum chip melting apparatus and a melting method that gasify the oil in the melting furnace, attract it to the heating burner of the melting furnace and burn it, and assist in replacing the fuel to save energy and prevent air pollution. It is disclosed as a technology.

WO2017 / 051586 ([0008], [0028-0029], [FIG. 1])

  The prior art removes moisture from the water-containing cutting oil, dissolves aluminum chips accompanied only by oil, and obtains a molten aluminum, and gasifies the oil in the cutting oil to partially replace the fuel of the melting burner. It has features in terms of recovery of aluminum resources and prevention of air pollution, such as being able to do so, but in the method of melting the remaining chips in the molten aluminum, the molten aluminum is caused by gasifying the oil in the molten aluminum There were problems such as having an adverse effect on the productivity and quality of food. The oil content of the cutting oil contains a large amount of oxygen atoms in the form of fatty acids and the like, and when the chips are put into an aluminum melt and dissolved, a large amount of aluminum oxide, so-called scum, is generated together with a large amount of smoke. generate. In addition, the hydrogen content of the molten aluminum is increased, which may cause quality deterioration.

  The present invention solves these problems, and removes the oil and moisture of the water-containing cutting oil by pretreatment of the aluminum chips accompanying the water-containing cutting oil, and then dissolves the pretreated aluminum chips in the form of aluminum. An object of the present invention is to provide a method for melting aluminum chips, which is basically obtained by melting in a furnace to obtain a high-quality aluminum melt with a high yield.

In order to achieve the above object, an aluminum chip melting method according to claim 1 of the present invention is a method for obtaining a molten aluminum by melting aluminum chips to which water-containing cutting oil is adhered, and Preheat aluminum chips in a temperature range from the temperature at which the water content of the water-containing cutting oil evaporates and the oil has completely decomposed and evaporated to the temperature at which rapid oxidation of the aluminum chips occurs. In the preheating step, and then in the state where the preheated aluminum swarf is cut off from the atmosphere, the charging step of pushing into the molten aluminum in the aluminum smelting furnace, and then in the molten aluminum in the aluminum smelting furnace A preheated aluminum chip is pushed into a chip floating prevention area and forcedly stirred and mixed to quickly diffuse and dissolve to dissolve the aluminum. A melting step of obtaining a melt that consists of the features.

  In many cases, a water-containing cutting oil, which is an emulsion obtained by diluting a water-soluble cutting oil with water, is used as a cutting oil used for producing an aluminum product by cutting aluminum. Therefore, since the aluminum chip which is cutting waste accompanies 10-30 wt% of cutting oil with respect to a water-containing cutting oil chip, the mixture of oil and water will adhere. The breakdown is that the oil content is 5 to 15 wt% and water is 5 to 25 wt%. This oil is usually rich in unsaturated fatty acids and contains oxygen elements in the form of hydroxyl groups (OH) and carbonyl groups (COOH), so aluminum chips are charged into the molten aluminum and dissolved. In some cases, the oxygen molecules oxidize the molten metal and generate scum of aluminum oxide, which causes a problem that the melting yield is lowered and the molten metal quality is also deteriorated.

  In order to solve the above-mentioned problem, in the preheating step which is one of the constitutions of claim 1 of the present invention, a process for removing moisture and oil from the water-containing cutting oil accompanying the aluminum chips by heating and evaporation is performed in the atmosphere. Is performed in the state that is shut off. This preheating process can sufficiently remove oxygen caused by the water-containing cutting oil from the aluminum chips, and in the subsequent melting process, oxygen reacts with the molten metal to generate a large amount of scum, resulting in a decrease in melting yield. To prevent. Moreover, it prevents that the quality of the molten aluminum deteriorates due to generation of alumina or hydrogen. By this preheating process, the production of molten aluminum from aluminum chips can be performed smoothly with improved quality.

  In order to prescribe the temperature at which the moisture and oil derived from the water-containing cutting oil of the aluminum chips of the present invention are evaporated and removed in the preheating step, the water-containing cutting oil is heated to evaporate the water and the oil is also evaporated. In order to make it possible, a thermogravimetric-differential thermal analysis (TG-DTA analysis) of the cutting fluid to be treated was performed. As a result, it was found that the water was removed by heating up to around 135 ° C., and the oil was oxidized and generated heat in the region of 200 to 500 ° C. (see FIG. 2). Moreover, according to the thermogravimetric-differential thermal analysis (TG-DTA analysis) when the aluminum powder is heated in the atmosphere, the aluminum powder exhibits a rapid exotherm and weight increase near 580 ° C., and the aluminum powder is oxidized. Has occurred (see FIG. 3). Based on these analysis results, the preheating temperature is specified in the temperature range from the temperature at which the water content of the hydrous cutting oil evaporates and the oil component finishes decomposing and evaporating to the temperature at which abrupt oxidation of aluminum chips occurs, It is preferable to preheat the aluminum chips to a temperature at which the cutting oil is decomposed and evaporated in the range of 500 to 570 ° C. When the oxidation was judged by the color of the oxide film on the surface of the chip, the aluminum alloy was the same as aluminum.

  In addition, the preheating process is performed by shutting off the atmosphere to prevent reoxidation of the aluminum chips as the temperature of the aluminum chips rises, and to generate dust explosion of the fine powder of aluminum chips generated by preheating. It is for preventing. This air blocking is performed by a non-oxidizing gas generated by heating, evaporating and decomposing water-containing cutting oil adhering to the aluminum chips. Incidentally, when aluminum chips are kept in the atmosphere at 600 ° C. for 1 hour, the experimental results are obtained in which the surface of the chips is covered with an alumina shell of 1.22% by weight. Although this alumina shell is estimated to be extremely thin from the weight ratio, it is considered that the chips that float on the surface of the molten metal do not dissolve.

  The preheating of the aluminum chips needs to be performed with the atmosphere cut off and must be indirectly heated so that the oxygen content can be cut off and preheated. In order to heat aluminum chips to a temperature range of 360 ° C. to 570 ° C., in the case of a melting furnace that normally uses combustion heating for melting aluminum chips, indirect heating using high-temperature combustion exhaust gas should be used. Can do. In the case of a melting furnace using electric heating, it is necessary to use electric heating or combustion heat separately.

  The charging step and the melting step following the preheating step are a charging step in which the preheated aluminum swarf is cut off from the atmosphere and pushed into the molten aluminum in the aluminum smelting furnace, and then the aluminum swarf melting This is a melting process in which aluminum chips preheated in a chip floating prevention region in the molten aluminum in the furnace are pushed in and forcedly stirred and mixed to rapidly diffuse and melt to obtain molten aluminum.

  The bulk specific gravity of the aluminum chips is about 0.3, and the specific gravity of the molten aluminum is 2.4. If the aluminum chips are simply put into the molten aluminum, the aluminum chips float. Aluminum is a metal that is easily oxidized thermodynamically, and can easily form alumina in an oxide film in the air. This alumina has an extremely high melting point of 2000 ° C. or higher, and is too high to be melted because it is higher than the melting point of the molten aluminum 660 ° C. Therefore, if aluminum chips are simply put into the molten aluminum, they will float, and the surface will form oxide-coated alumina, which will remain floating as scum. Prevent it from being thrown into.

  In order to solve this problem, in the charging process following the preheating process, the preheated aluminum chips are cut off from the atmosphere and pushed into the chip floating prevention area in the aluminum melt of the aluminum chip melting furnace. In the subsequent melting step, the preheated aluminum chips pushed into the chip floating prevention region can be forcibly stirred and mixed and melted while rapidly diffusing to obtain a molten aluminum.

  With this configuration, the pre-heated aluminum chips are pushed into the chip floating prevention region in the molten aluminum in the aluminum chip melting furnace in a sealed state where the pre-heated aluminum chips are cut off from the atmosphere. Specifically, the preheated aluminum chips can be forcibly pushed into the molten metal with a piston-like push rod after charging the preheated aluminum chips.

  In addition, the swarf prevention area in the molten aluminum of the melting furnace is an area with a ceiling with a downward inclined surface around it in order to completely prevent the swarf of the aluminum chips pushed into the melt ( For example, a Jinkasa-shaped region) is provided, and the chips are pushed into the region to completely prevent the chips from short-circuiting and rising. At the place where the peak of the downward slope of the area hits, mechanical stirring with blades to destroy the alumina shell covering the surface of the chip and disperse the chip to improve the mixing with the molten metal and promote the dissolution Equipment is provided. As a result, an upward flow and a downward flow are generated, the chips are placed on the flow and moved toward the stirring blade along the ceiling, and the alumina shell is broken by being caught in the stirring blade. It is possible to promote the dissolution of the chips without floating up.

  Moreover, the aluminum chip melting method according to claim 2 is the aluminum chip melting method according to claim 1, wherein the hydrous cutting oil decomposition / evaporated gas and the aluminum powder fine powder generated in the preheating step are combusted. It is characterized by adding a gas treatment process that is oxidized and made pollution-free by treatment.

With this configuration, the decomposition / evaporation gas of the water-containing cutting oil generated in the preheating step contains a combustible gas containing CO, hydrocarbons, H _{2 and the} like and fine aluminum, which is subjected to a combustion treatment or a high temperature. Combustible gas is combusted by mixing combustion gas and oxygen if necessary. Also, aluminum fine powder that may explode dust is changed to aluminum oxide. The process which eliminates is performed.

When using a melting furnace that burns and heats fuel for melting aluminum chips, the cracked and evaporated gas in the high-temperature combustion gas is mixed with oxygen, if necessary, and burned. Do. Further, in the case of a melting furnace using electric heating, oxygen can be mixed with the decomposed evaporative gas and a combustion treatment can be performed in a flue or the like to make pollution-free.

Moreover, the aluminum chip melting method according to claim 3 is the oil chip separation method according to claim 1 or 2, wherein the amount of water-containing cutting oil adhering to the aluminum chip is reduced before the preheating step. It is characterized by adding a sizing process for slicing and sieving to increase the bulk density of the process and the chips.

By separating and reducing the water-containing cutting oil from the aluminum chips in the oil-water separation process, it is possible to easily remove and evaporate the water in the water-containing cutting oil of the aluminum chips and decompose and evaporate the oil in the next preheating process. The chips can be preheated sufficiently. In the oil-water separation step, it is usually preferable to provide a centrifugal oil-water separator, which can easily reduce the content of the water-containing cutting oil from 10 to 30% to 2 to 5%. It is possible to improve the melting ability of aluminum chips accompanied with oil, or to allow the melting treatment of aluminum chips accompanied by excessive water-containing cutting oil. Further, according to this configuration, it is not necessary to use heat energy such as heating in the deoiled water, which contributes to energy saving in terms of dehydration and preheating, and there is no concern about air pollution.

By sieving and cutting in order to increase the bulk density of the aluminum chips in the sizing process, the amount of gas entrained in the chips can be minimized in the melting process of the melting furnace. The speed does not depend on the size of the particle size, and the dissolution becomes stable and fast. As a result, the chips are not oxidized and transferred to the slag, the melting yield is increased, and the quality of the molten aluminum can be maintained well. In addition, when the aluminum chips to be processed are sized before the centrifugal oil / water separator, the oil / water separation from the aluminum chips can be performed stably, and the cutting oil content can be reduced.

According to a fourth aspect of the present invention, there is provided an aluminum chip melting apparatus including a Jinkasa ceiling that forms a chip floating prevention region in the molten metal of an aluminum chip melting furnace and spaced downward from the molten metal surface, and a circulating molten metal below the Jinkasa ceiling. A stirrer having a stirring blade for generating a flow, and a chip cutting portion opened in the circulating molten metal flow in the Jinkasa ceiling, and the aluminum chips are charged into the circulating molten metal and floated on the molten metal surface It is characterized in that it melts without melting to obtain molten aluminum.

With this configuration, the chips charged in the circulating molten metal flow are blocked by the Jinkasa ceiling, float on the hot water surface, stay in the molten metal flow without loss, and are well melted. Further, the chips repeatedly collide with the stirring blade, and further dissolution proceeds.

According to a fifth aspect of the present invention, there is provided an aluminum chip melting apparatus comprising: a pump cylinder having a lower end opened in a molten metal of an aluminum chip melting furnace and spaced downward from a molten metal surface to form a chip floating prevention region; and the pump cylinder A downward discharge port provided in the upper portion, a stirrer having a stirring blade for generating a circulating molten metal flow in the pump cylinder, and a chip cutting portion opened in the circulating molten metal flow by the pump cylinder, The powder is charged into the circulating molten metal and melted without floating on the molten metal surface to obtain a molten aluminum.

With this configuration, the molten metal flow generated by the stirring blades is forcibly circulated from the pump cylinder to the discharge port without diffusing to the surroundings, so that the chips introduced into the molten metal flow are not diffused to the surroundings. Dissolution occurs. Further, since the circulating flow can be less likely to leak in the direction of the molten metal surface, the molten metal surface is stable, and generation of alumina scum due to reoxidation of the molten metal can be extremely reduced.

Further, in the aluminum chip melting apparatus according to claim 6, the stirring blade of the stirrer is the aluminum chip melting apparatus according to claim 4 or 5, wherein the screw type stirring blade, the propeller type stirring blade or the screw propeller integrated type is used. It is one of the stirring blades.

With this configuration, a stirring blade can be selected, the directionality and strength of the circulating molten metal flow can be selected, and the leakage of the molten metal flow to the molten metal surface in the stirrer axis direction can be suppressed by the combination of the stirring blades.

The aluminum chip melting apparatus according to claim 7 is the aluminum chip melting apparatus according to claim 4, 5 or 6, wherein the rotation shaft of the stirrer passes through the top of the Jinkasa ceiling or the pump cylinder in the molten metal. The portion is provided with a seal mechanism for preventing the circulating molten metal flow by the stirring blade from rising to the molten metal surface.

With this configuration, the molten metal rises from the penetrating portion and the surface of the molten metal dances, the molten metal is easily oxidized, the scum of the aluminum oxide increases, the melting yield of the molten aluminum deteriorates, and the melting work is smooth. It prevents the inhibition.

According to the aluminum chip melting method according to the first to third aspects of the present invention, a high quality molten aluminum can be obtained using aluminum chips accompanied by a water-containing cutting oil as a raw material. As a result, aluminum resources can be recovered from aluminum chips, contributing to resource utilization and energy saving. Further, according to the method of the present invention, in the removal of the water-containing cutting oil, unlike the conventional method, it is a method capable of performing clean evaporation / decomposition and combustion treatment without fear of pollution such as air pollution. In addition, this aluminum chip melting method can be reliably carried out using equipment and equipment that has been used, and it can be used to obtain a molten aluminum of better quality than before. It is an environmentally superior method that saves space and does not cause air pollution. Moreover, according to the aluminum chip melting | dissolving apparatus of Claim 4-7 which concerns on this invention, it can melt | dissolve aluminum chip efficiently, can melt | dissolve by stabilizing the molten metal surface, and chip Since scumming can be prevented and re-oxidation of the molten metal can be prevented, it is possible to improve the aluminum melting yield and the quality of the molten aluminum.

FIG. 1 is a flowchart showing the method for melting aluminum chips of the present invention. FIG. 2 is a representative example of a thermogravimetric-differential thermal analysis chart of the water-containing cutting oil for aluminum. FIG. 3 is a representative example of a thermogravimetric-differential thermal analysis chart in which aluminum powder is heated in the atmosphere. FIG. 4 is a schematic front sectional view of an aluminum chip melting apparatus according to an embodiment for carrying out the method of the present invention. FIG. 5 is a schematic cross-sectional view of an apparatus for melting molten metal in a molten metal of an aluminum chip melting furnace according to an embodiment for carrying out the present invention, wherein (a) is a Jinkasa ceiling and a screw stirring blade type; (B) is a Jinkasa ceiling and a propeller stirring blade type, (c) is a pump cylinder with a downward discharge port and a propeller screw stirring blade type.

Referring to the flow chart of FIG. 1, the steps of the method for dissolving aluminum chips accompanied by water-containing cutting oil according to the present invention will be described. The aluminum chips accompanied by water-containing cutting oil composed of emulsion oil and water are: According to the water content, the water content is reduced through an oil / water separation step. And the sizing process which adjusts the particle size of a chip can be added (a). Next, a preheating step (b) for preheating and deoiling moisture of the aluminum chips accompanying the water-containing cutting oil, a charging step (c) for charging the preheated aluminum chips to the melting furnace while blocking the atmosphere, and a molten aluminum Is composed of a melting step (d) in which aluminum chips are charged and melted in a melting furnace that is heated and held, and a gas treatment step (e) in which the oil-water vapor evaporated in the preheating step is combusted.

An aluminum chip melting apparatus 1 as an embodiment to which the method of the present invention is applied will be described with reference to FIG. The aluminum chip melting apparatus 1 includes a preheating device 4 that removes moisture and oil in the cutting oil adhered to the aluminum chip, and a chip that charges the preheated aluminum chip into the molten metal M of the crucible melting furnace 2. An aluminum melting apparatus for producing a molten aluminum M by melting aluminum chips preheated using a charging device 5, a crucible type melting furnace 2 indirectly heated by a combustion burner 6, and evaporated from the preheated aluminum chips It comprises an oil combustion device that attracts oil to the combustion burner 6 for combustion treatment.

Further, a centrifugal oil-water separator and a sizing device (not shown) are provided in the front stage of the aluminum chip dissolving device 1 to reduce the amount of cutting oil adhering to the aluminum chip, that is, the amount of oil and water, and the aluminum chip. A pretreatment for adjusting the size to a certain particle size range by sizing such as cutting and sieving can be performed. This pretreatment means can easily reduce the excess oil moisture in the cutting oil with the centrifugal oil-water separator without physically heating, and also adjust the particle size to increase the volume of the chip. The density can be increased to facilitate the subsequent processes of preheating, charging, and melting, and then, further heat dehydration and deoiling can be performed with the screw conveyor 4-2 that is a preheating means of the aluminum chip melting apparatus 1, Aluminum chips can be preheated by efficiently reducing moisture and oil content in cutting oil. Further, according to this apparatus, since the exhaust gas of the melting furnace heating combustion process is used as a heat source in deoiled water, it is not necessary to newly use heat energy such as heating, and there is a concern about air pollution associated therewith. Nor.

In addition, a granulating device comprising crushing and sieving can be provided at the front stage or the rear stage of the centrifugal oil-water separator. This reduces and stabilizes the variation in the particle size and shape of the aluminum chips, making it easy to operate in the preheating, charging, and melting processes of the aluminum chips, and in particular, reducing the amount of gas trapped in the chips during the melting process. This stabilizes the melting and leads to easy obtaining of a good quality molten aluminum.

  The aluminum swarf treated by the method of the present invention is mainly composed of cutting waste generated when aluminum or an aluminum alloy is cut to produce an aluminum product. Accordingly, the aluminum chips are accompanied by 10 to 30 wt% of cutting oil with respect to the cutting oil-containing chips 100, and the cutting oil is usually 5 to 15 wt% because an emulsion of oil and water is used. A mixture of oil and 5-25 wt% water is adhered. An aluminum chip melting apparatus 1 using the method of the present invention is a method of heating and evaporating and removing moisture and oil from a cutting oil accompanying an aluminum chip in a preheating step, and then charging the molten aluminum into a melting furnace 2. In addition to obtaining M, oil and water are evaporated in the preheating step and burned in the heating and combustion section 6-1 of the melting furnace 2. This makes it possible to recover aluminum from aluminum chips and to treat the accompanying cutting oil without causing pollution such as air pollution.

  Moreover, the preheating device 4 in the aluminum chip melting apparatus 1 cuts out the aluminum chips from the chip hopper 4-1 with a preheating screw conveyor 4-2 that is rotationally driven by a variable speed drive geared motor 4-2e. While transporting, the screw conveyor 4-2 is inserted into the preheating duct 4-3, and the temperature of the combustion exhaust gas from the crucible melting furnace 2 is adjusted in the screw conveyor outer cylinder 4-2b into the preheating duct 4-3. Preheat the aluminum chips by guiding and heating.

At this time, the temperature for drying and preheating the aluminum chips is in the range of 360 ° C. to 570 ° C., preferably 500 to 570 ° C. Normally, aluminum chips are accompanied by oil and moisture derived from cutting oil. Therefore, in the present invention, cutting oil used for the purpose of evaporating moisture and oil by heating (trade name: cedar cut CS-68DN-). The thermogravimetric-differential thermal analysis (TG-DTA analysis) of 2) was performed. As a result, as shown in FIG. 2, it was found that moisture was removed by heating up to around 135 ° C., and the oil component was oxidized and generated heat in the region of 200 to 500 ° C. Moreover, it turned out that an oxidation reaction becomes remarkable around 580 degreeC of aluminum powder (refer FIG. 3). Based on this, by setting the preheating temperature of the aluminum chips to 500 to 570 ° C., oil and water can be removed in an evaporated state. Subsequently, when the aluminum chips are handled and melted in the melting furnace 2 in a state where the atmosphere is shut off, the melting can be maintained at a high temperature without lowering the melting temperature in the melting furnace 2. Since the preheating temperature of the powder is as high as 500 to 570 ° C., there is little generation of aluminum oxide, and the scum mainly composed of this is reduced, leading to reduction of impurities, hydrogen content and the like of the molten aluminum M.

Moreover, as shown in FIG. 4, the crucible melting furnace 2 of the aluminum chip melting apparatus 1 is surrounded by a furnace wall refractory 7-1, a furnace lid refractory 7-2, and a furnace bottom refractory 7-3. It is installed on the furnace mounting table 2-3 in the melting furnace combustion chamber 7. The melting furnace combustion burner 6 is provided at a corner near the bottom of the melting furnace combustion chamber 7, and the combustion exhaust gas outlet is provided above the melting furnace combustion chamber 7 with the axis of the combustion burner 6 being shifted. Therefore, the flame of the combustion burner 6 heats the crucible melting furnace 2 as a swirling flow licking the outer wall of the crucible melting furnace 2 from the bottom to the top. The crucible melting furnace 2 is mainly formed of a carbonaceous refractory in a bowl shape, holds an aluminum melt M having a melting point of about 660 ° C. inside, and a swirl flow flame from the bottom to the top of the melting furnace combustion burner 6. Therefore, the melting furnace 2 is indirectly heated by the combustion burner 6. Usually, the combustion chamber temperature of the melting furnace is in the range of 700 ° C to 1000 ° C. The crucible melting furnace 2 has an aluminum chip melting amount of 50 to 100 kg / hr and a diameter of about 600 mm and a height of about 500 mm.

Moreover, as shown in FIG. 4, the crucible type aluminum melting furnace 2 of the aluminum chip melting apparatus 1 is divided into a molten metal part 2-b and a molten part 2-a in the radial direction of the molten metal M pool. Furthermore, a reverse saddle-shaped Jinkasa ceiling 2-2 is provided below the molten metal surface of the melting part 2-a. The Jinkasa ceiling 2-2 includes a stirring blade 3-1 driven by a stirrer 3. The vertical swirl flow area generated by the stirring blade 3-1 in the lower area of the Jinkasa ceiling 2-2 is the chip floating prevention area. Regarding the melting of the aluminum chips, the preheated aluminum chips are melted in the molten metal M in the chip floating prevention region below the Jinkasa ceiling 2-2 of the melting furnace 2 by the inclined charging pusher 5-2 of the charging device 5. It is possible to promote the dissolution of the aluminum chips by being pushed in from the chip cutout section 5-2b and forcibly stirring and dispersing the aluminum chips over a wide range with the stirring blade 3-1. Further, when the chips collide with the stirring blade 3-1, the chips are further dispersed, and the oxide film on the surface of the chips is broken to promote dissolution.

Further, as shown in FIG. 4, the chip charging device 5 of the aluminum chip melting apparatus 1 is provided with an inclined charging pusher 5-2 having a charging port on the lower surface of the charging hopper 5-1. Can do. The inclined charging pusher 5-2 is provided on the chip cutting part 5-2b from the lower surface of the charging hopper 5-1 to the lower part of the Jinkasa ceiling 2-2 of the melting part 2-a of the crucible melting furnace 2. It is provided so that it may be immersed, and the preheated aluminum chips can be pushed into the molten metal M by the charging pusher 5-2. Although it is intermittent by this inclined charging pusher 5-2, it is possible to forcibly insert into the flow of the molten metal M in the lower area of the Jinkasa ceiling 2-2 by forcibly increasing the filling degree of aluminum chips. It becomes. In addition, according to the inclined charging pusher 5-2, the filling degree is increased so that gas is not forced to enter the aluminum chips without being greatly affected by the properties such as the particle size of the aluminum chips, and the molten metal flow. It is possible to push in.

Further, the oil and water evaporated in the preheating screw conveyor 4-2 of the aluminum chip preheating device 4 is sent to the chip hopper 5-1 by suction of the oil gas blower 9-1 through the upper space of the preheating screw conveyor 4-2. The oil moisture gas accumulated in the upper space of the chip hopper 5-1 is provided with an oil gas duct 9 connected to the combustion part 6-1 of the combustion burner 6 from the oil gas suction port 9-2, and the chip hopper 5-1 The accumulated oil moisture gas can be attracted and guided and burned in the combustion section 6-1 including the flame of the melting furnace combustion burner 6. Thereby, air pollution by oil can be prevented.

Moreover, when the melting operation | work using the aluminum chip melt | dissolving apparatus 1 which concerns on this invention is described generally, according to the amount of cutting oil containing cutting oil aluminum cutting powder, it will be in front of a centrifugal oil-water separator and a sizing apparatus. A preheating screw using the exhaust gas from the combustion burner 6 of the crucible melting furnace 2 can be selected, and then the aluminum chips accompanied with the cutting oil are in the range of 360 to 570 ° C., preferably 500 to 570 ° C. Preheated by indirect heating on the conveyor 4-2 to evaporate the oil and water in the cutting oil, then the preheated aluminum chips and evaporated oil and water are separated in the preheated screw conveyor 4-2, and then the preheated The molten aluminum chips are pushed into the chip floating prevention area below the Jinkasa ceiling 2-2 of the melting part 2-a of the crucible type melting furnace 2 heated by the combustion burner 6 and stirred and dissolved. More, dissolved aluminum is to obtain a clean aluminum melt M by migrating molten metal from the melting unit 2-a of the crucible-type aluminum melting furnace 2 to melt section 2-b. The separated oil / water vapor and fine aluminum powder are combusted in the combustion section 6-1 of the combustion burner 6 of the melting furnace 2 via the oil gas duct 9.

In the preheating process of the aluminum chips that are the raw material, the outer cylinder 4-2b of the preheating screw conveyor 4-2 is heated with melting furnace combustion exhaust gas at a predetermined temperature, so that the conveying aluminum chips of the screw conveyor 4-2 are accompanied. The moisture and oil are evaporated, while the aluminum chips are preheated and can be sent to the charging hopper 5-1 of the next-stage chip charging apparatus 5 while blocking the atmosphere. The preheated aluminum chips from the preheating screw conveyor 4-2 are discharged to the charging hopper 5-1, and when the oil and water are evaporated, the vapor is sent to the space of the chip hopper 4-1. It is burned through the oil gas duct 9-1 and diffused into the atmosphere. Further, the preheated aluminum chips are deposited in the charging hopper 5-1 and then charged into the melting furnace 2.

Also, preheated aluminum chips are forcibly dissolved in the melting furnace 2 from the charging hopper 5-1 intermittently from the chip cutting part 5-2b of the inclined charging pusher 5-2. It can be charged into the molten metal M in the lower area of the Jinkasa ceiling 2-2 of the part 2-a. Moreover, by the stirring of the stirring blade 3-1 of the stirrer 3 close to the chip charging area, the charged aluminum chip is rapidly dissolved and becomes the molten metal M by diffusion. Next, the molten aluminum M moves to the molten metal part 2-b and is finally discharged from the hot metal 2-1 to a molten metal pan (not shown).

As mentioned above, aluminum chips with cutting oil are used as raw materials, the accompanying oil moisture is evaporated, and the preheating of the aluminum chips reduces the temperature drop of the molten metal, so the melting proceeds quickly. By reducing the reoxidation of the molten metal, there is no scum formation, and the dissolved oxygen amount of the molten aluminum is lowered, so that the quality deterioration is small. Moreover, the molten aluminum M can be obtained with a good yield. Incidentally, the molten metal 98 and the oxide scum 2 can be obtained with respect to the preheated aluminum chip weight 100. The oil component is evaporated by the preheating screw conveyor 4-2, and is combusted by the combustion burner 6 of the melting furnace 2 via the chip hopper 5-1. The present invention is an aluminum chip melting method that is suitable for resource saving and energy saving and does not cause air pollution.

FIG. 5 is a schematic cross-sectional view of an apparatus for melting molten metal in a molten metal in an aluminum chip melting furnace according to the present invention. FIG. 5 (a) shows a Jinkasa ceiling and a screw stirring blade type. , (B) is a Jinkasa ceiling and a propeller stirring blade type, (c) is a pump cylinder with a downward discharge port and a propeller screw stirring blade type. The melt | dissolution apparatus in the molten metal of a charging chip is demonstrated using FIG.

As shown in FIGS. 5 (a) and 5 (b), the crucible type aluminum melting furnace 2 of the aluminum chip melting apparatus 1 includes a molten metal portion 2-b and a molten portion 2-a in the vertical direction of the molten metal M pool. It is configured to be divided, and further includes an inverted saddle-shaped Jinkasa ceiling 2-2 below the molten metal surface 2-c of the melting part 2-a. The Jinkasa ceiling 2-2 includes a stirring blade 3-1 driven by a stirrer 3, 3-1a is a screw stirring blade, and 3-1b is a propeller stirring blade. The vertical molten metal flow area F generated by the stirring blade 3-1 in the lower area of the Jinkasa ceiling 2-2 is the chip floating prevention area. By simply comparing the action of the screw stirring blades of 3-1a and the propeller stirring blades of 3-1b, the former is considered to have a large stirring flow rate, and the latter is considered to have a pulverizing effect. Can be used properly. Regarding melting of the aluminum chips, the preheated aluminum chips are a molten molten metal that is a chip floating prevention region below the Jinkasa ceiling 2-2 of the melting furnace 2 by the inclined charging pusher 5-2 of the charging device 5. It is possible to accelerate the dissolution of aluminum chips by being pushed in from the chip cutting part 5-2b in the flow F and forcibly stirring and dispersing the aluminum chips over a wide range with the stirring blade 3-1. Further, when the chips collide with the stirring blade 3-1, particularly with the propeller stirring blade of 3-1b, the chips are further dispersed, and the oxide film on the surface of the chip is broken to promote dissolution. In addition, it is preferable to provide a seal blade 3-2 that prevents the molten metal from rising from the gap between the stirrer shaft 3a and the Jinkasa ceiling 2-2 and preventing the molten metal surface 2-c from wavy.

FIG. 5 (c) is provided in the upper part of the pump cylinder 2-2 b and the upper part of the pump cylinder 2-2 b, which is spaced downward from the molten metal surface 2- c in the molten metal M and forms a chip floating prevention region. A downward discharge cylinder 2-2c, a stirrer 3 having a stirring blade 3-1 for generating a circulating molten metal flow F in the pump cylinder 2-2b, and a chip cutting portion 5- 2b. The stirring blade 3-1 includes a propeller stirring blade 3-1b that forms an upward main flow at the lower portion of the stirrer shaft 3a, and forms a weak downward flow at the upper portion of the stirrer shaft 3a. It is preferable to provide a screw stirring blade 3-1a having the second role. With this configuration, the molten metal flow F generated by the stirring blade 3-1 is forcibly circulated from the pump cylinder 2-2b to the discharge cylinder 2-2c without diffusing to the periphery, so that the molten metal flow F is charged into the molten metal flow F. The swarf is efficiently dissolved without diffusing around. Further, since the circulating flow can be less likely to leak in the direction of the molten metal surface 2-c, the molten metal surface 2-c is stable, and generation of alumina scum due to reoxidation of the molten metal M can be extremely reduced.

Not only can it be used in the field of processing aluminum chips, but it can also be applied in the field of processing of zinc, magnesium metal and their alloy chips.

1: Aluminum chip melting device
2: Aluminum chip melting furnace 2-a: Melting part 2-b: Molten metal part
2-c: Hot water surface 2-2: Jinkasa ceiling 2-2b: Pump cylinder 2-2c: Discharge cylinder 2-3: Furnace mounting table 3: Stirrer 3a: Stirrer shaft 3-1: Stirring blade 3-1a: Screw stirring Blade 3-1b: Propeller stirring blade 3-2: Seal blade
4: Preheating device 4-1: Chip hopper 4-2: Screw conveyor 4-2a: Screw blade 4-2b: Conveyor outer cylinder 4-3: Preheating duct 4-2d: Discharge end Exit 5: Chip charging device 5-1 Charging hopper 5-2: Charging pusher 5-2b: Chip cutting part 6: Melting furnace combustion burner 6-1: Combustion part 7: Melting furnace combustion chamber 7-1: Furnace wall refractory 7-2 : Furnace ceiling refractory 7-3: Furnace bottom refractory 9: Oil gas duct 9-1: Oil gas blower 9-2 Oil gas inlet M: Molten metal F: Circulating molten metal flow

Claims (7)

This is a method for obtaining a molten aluminum by melting aluminum chips to which water-containing cutting oil is adhered, and the aluminum chips from the temperature at which the water content of the water-containing cutting oil evaporates and the oil components are completely decomposed and evaporated. In a temperature range up to a temperature at which rapid oxidation of the aluminum chips occurs, a preheating step of preheating the aluminum chips by shutting off the atmosphere, and then, in a state where the preheated aluminum chips are shut off from the atmosphere, A charging process in which the molten aluminum is pushed into the molten metal, and then the aluminum chips preheated into the chip floating prevention area in the molten aluminum in the molten aluminum chip are pushed in and forcedly mixed. And a melting step of rapidly diffusing and melting to obtain molten aluminum, and a method for melting aluminum chips. The method for melting aluminum chips according to claim 1, further comprising a gas treatment step of decomposing and evaporating gas of the water-containing cutting oil generated in the preheating step to make it non-polluting. 2. An oil / water separation step for reducing the amount of water-containing cutting oil adhering to the aluminum chips and a sieving step for slicing and sieving to increase the bulk density of the chips before the preheating step. Or the melt | dissolution method of the aluminum chip of 2. A Jinkasa ceiling that forms a chip levitation prevention region in the molten metal of the aluminum chip melting furnace and that is spaced downward from the molten metal surface, a stirrer having a stirring blade that generates a circulating molten metal flow below the Jinkasa ceiling, and in the Jinkasa ceiling And a chip cutting part opened in the circulating molten metal flow, and the aluminum chip melting apparatus for obtaining the molten aluminum by melting the aluminum chips into the circulating molten metal without floating on the molten metal surface . A pump cylinder having a lower end that is spaced downward from the molten metal surface to form a chip floating prevention area in the molten metal of the aluminum chip melting furnace, a downward discharge port provided in the upper part of the pump cylinder, and the inside of the pump cylinder A stirrer having an agitating blade for generating a circulating molten metal flow, and a chip cutting portion opened in the circulating molten metal flow by the pump cylinder, and charging the molten aluminum into the circulating molten metal An aluminum chip melting device that melts without being floated to obtain molten aluminum. The aluminum chip melting apparatus according to claim 4 or 5, wherein the stirring blade of the stirrer is any one of a screw type stirring blade, a propeller type stirring blade, or a screw propeller integrated type stirring blade. The sealing mechanism for preventing the circulating molten metal flow by the stirring blade from rising to the molten metal surface is provided at a portion where the rotation shaft of the stirrer penetrates the top of the Jinkasa or the upper part of the pump cylinder in the molten metal. Item 7. The aluminum chip melting apparatus according to Item 4, 5 or 6.

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