WO2003038138A1

WO2003038138A1 - Non-ferrous melt refinement and equipment

Info

Publication number: WO2003038138A1
Application number: PCT/CN2002/000741
Authority: WO
Inventors: Desheng Huang
Original assignee: Desheng Huang
Priority date: 2001-10-30
Filing date: 2002-10-22
Publication date: 2003-05-08

Abstract

A refining process for non-ferrous melt and equipment thereof. The process, including an adsorbing purification by letting a purified gas pass through the non-ferrous melt, is characterised in that, a vaccume is applied above the non-ferrous melt while the gas adsorbing refinement is undergoing to form a reduced pressure drawing the molten metal. The equipment is composed of a non-ferrous melting and treating device and a vaccum device, the vaccum device therein is connected with the space above the melt in the non-ferrous melting and treating device. The said melting and treating device may be single-chamber, multi-chamber, or chamber-free constitution. The refining process of present invention makes it possibles either for meeting the requirements of environment protection, or of the achievement of high efficiency, energy saving and low consumption. The refining equipment of present invention can make the said process more easily to be carried out.

Description

Method and equipment for purifying non-ferrous metal melt

The invention relates to a method for purifying a non-ferrous metal melt, in particular to an aluminum for purifying impurities such as hydrogen, oxides and other harmful substances in the molten aluminum liquid, purifying the aluminum liquid, and ensuring the quality and performance of the casting. Purification and refining method of molten metal, and equipment designed to realize the purification method. Background technique

During the melting process of aluminum alloy, hydrogen gas will be sucked in and the alumina slag will be oxidized. If these hydrogen and alumina slag are not removed, the casting may have pores, slag inclusion and other problems, which will inevitably affect the performance, strength and even appearance of the product negative effect. Therefore, after the aluminum alloy is melted, it must be purified to remove harmful impurities and reduce the hydrogen content, in order to obtain a pure metal liquid, and the quality and performance of the casting can be guaranteed.

The traditional treatment method is to directly pass a purification gas such as nitrogen, argon, chlorine or a refining agent to the bottom of the molten aluminum in the melting furnace. When the purification bubbles generated rise upward, the impurities in the molten aluminum, including hydrogen and hydrogen, are captured and captured along the way. Oxidation slag, bring them to the aluminum surface, hydrogen escapes from the surface of the molten aluminum, and the oxide slag is raked out of the furnace. This method is inefficient, uneven, and labor-intensive. In order to improve the purification effect and make the aluminum liquid be thoroughly and uniformly treated, relevant purification equipment came into being. More famously, there are FILD in Britain, ALPUR in France, HM-MAXIJET in Germany, ALCOA, SNIF, PAL and so on.

Whether it is FILD or SNIF, nor is it HM-MAXIJET, ALPUR or PAL, they have one thing in common, that is, they use traditional processing methods to pass nitrogen, chlorine, argon and other gases to the bottom of the aluminum solution to form large and small Bubbles, adsorb hydrogen and impurities suspended in aluminum solution, take them on aluminum and use graphite nitrogen diffusion tube buried in the bottom of the furnace, plus alumina beads to adsorb and filter impurities; HM-MAXIJET, SNIF, ALPUR, and PAL use rotation Rotor. The purification efficiency of the rotating rotor is higher than that of direct radiation. However, if the purification gas is only nitrogen, its purification efficiency is also not ideal.

In order to achieve the predetermined purification effect, on the one hand, the capacity of the equipment must be increased, which results in a huge structure and large related costs and losses. On the other hand, such as SNIF and ALPUR, the activation gas chlorine (Cl) is required. HM-MAXIJET, SNIF and PAL require injection of cleaning agents containing chlorine (CI) or fluorine (F); these are harmful to human health and the environment. In addition, in order to prevent the oxidation of the tumbling aluminum liquid and reduce aluminum consumption and impurities, these devices also need to use a covering agent such as aerobic (C1) or fluorine (F), which also has environmental issues. FILD uses LPG for thermal insulation, burning a lot of LPG every year, and ejecting a large amount of C02, which has a serious greenhouse effect and is not environmentally friendly. Summary of the Invention In order to solve the above problems, the present invention provides a method for purifying a non-ferrous metal melt, so that the purification treatment of the non-ferrous metal melt not only meets environmental protection requirements, but also achieves high efficiency, energy saving, and low consumption. The object of the present invention is also to Providing purification equipment required to implement the above method makes the above method easier to implement.

In order to achieve the above object, the present invention provides a method for purifying a non-ferrous metal melt, the method includes passing a purified gas through the non-ferrous metal melt from bottom to top to perform adsorption purification, and is characterized in that at the same time as gas adsorption purification, A vacuum is evacuated above the non-ferrous metal melt to form a negative pressure attraction to the melt.

The purification gas is an inert gas, preferably nitrogen.

The present invention further provides a device for implementing the above method, which is characterized in that the device is composed of a non-ferrous metal melting and processing device and a vacuum device, wherein the vacuum device is connected to a space above the melt in the non-ferrous metal melting and processing device.

The non-ferrous metal melting and processing device may be a single-chamber structure, a multi-chamber structure or a non-chamber structure.

A single-chamber structure non-ferrous metal melting and processing device is provided with a shell. The inner space of the shell constitutes a processing chamber. The upper part of the shell is equipped with a vacuum cover connected to a vacuum machine. The bottom of the shell is equipped with a purge gas diffusion plate. The bottom of the shell is equipped with a shutter. A metal liquid inlet and a metal liquid outlet are provided on the side, and a sight glass is mounted on the vacuum cover.

The single-chamber structure non-ferrous metal melting and processing device is provided with a cover. The top of the cover is equipped with a vacuum cover and a sight glass. The bottom is equipped with a base. The cover is equipped with a crucible. The bottom of the crucible is equipped with a bell-shaped purification gas diffusion tube. There is also a heater.

The multi-chamber structure non-ferrous metal melting and processing device is provided with a shell. The inner space of the shell is longitudinally divided into a cleaning chamber and a processing chamber. A vacuum chamber is arranged above the processing chamber. A heater is installed in the processing chamber and the cleaning chamber. The purification gas diffusion plate is provided with a metal liquid inlet and a metal liquid outlet on the shell, and a vacuum glass is installed on the vacuum chamber.

The non-ferrous metal melting and processing device without a chamber structure is provided with a vacuum cover and a sight glass on the upper part of the melting furnace, and a bell-shaped purification gas diffusion tube is installed in the furnace.

The contribution of the present invention is that the purification method organically combines two original irrelevant purification methods such as nitrogen (N) bubble adsorption and vacuum (V) negative pressure suction, and realizes the method through one device. In this method, gas adsorption and vacuum attract one by one, push and pull, and complement each other. Effectively solve the environmental protection, high efficiency, energy saving, low consumption and other industry coveted problems.

The high efficiency of the present invention is that the horizontal area of the purification equipment is 63 "* 43" and the FILD is 75 "* 118", that is, the horizontal area of the equipment of the present invention is less than one third of the FILD; Only half a ton, FILD is about 2 tons, and the semi-continuous casting speed is 400kg per minute. That is to say, the processing time of aluminum maggot when passing through this equipment is only over 1 minute, and it is 5 minutes when passing through FILD. However, the purification effect of aluminum liquid processed by this equipment is still better than FILD. Especially for magnesium (Mg) -containing aluminum alloys, we use the vacuum bubble measurement method with a vacuum degree of 29 InHg. As a result, the top of the aluminum liquid sample that has not been prepared is bulged upward, such as a hamburger. Sore holes; while the aluminum liquid sample processed by it has a regular depression at the top toward the center, The profile is dense. The two are in stark contrast. It is difficult for FILD to have such a clear comparison. The performance of French ALPUR is worse than FILD, and the purification effect of 40 minutes is not as good as 5 minutes of FILD.

The environmental protection effect of the present invention is shown in the following. First, the present invention does not use chlorine (C1) or chlorine (C1) or fluorine (F) -containing cleaning agents that are harmful to human health, but uses harmless human health and the environment. And cheap nitrogen. The present invention mainly relies on a combination of completely physical methods such as nitrogen (N) bubble adsorption and vacuum (V) negative pressure suction to purify aluminum liquid. Secondly, in the process of purifying the aluminum liquid, the top of the processing chamber of the device of the present invention is vacuum-free and oxygen-free, and the rolled aluminum liquid cannot oxidize with oxygen. Therefore, it is not necessary to sprinkle a surface of the aluminum liquid like other types of purification equipment. The covering agent containing chlorine (C1) or fluorine (F) can also effectively prevent the oxidation of aluminum liquid to generate alumina slag. In use, the above FILD consumes a large amount of money each year and generates a large amount of C02, which seriously pollutes the working environment and is not environmentally friendly. The invention adopts an immersion type electric heating rod, and the heat generated can be completely absorbed by the aluminum liquid, which not only saves energy, but also greatly improves the environment. When other purification equipment is used, the equipment and its surroundings are filled with oxidized powder residue, and the equipment is always kept clean. It can be seen that the present invention completely solves the environmental protection problems existing in other purification equipment, and is therefore definitely an environmental protection-type purification equipment.

The low power consumption of the present invention is manifested in the high purification efficiency of the device. In order to achieve the same purification effect, the volume used is small, and three 8kw electric heating rods are used for heating. FILD is heated by LPG, which is over 1.2 million Hong Kong dollars per year. Compared with FILD, using this equipment can save more than one million Hong Kong dollars in energy expenditure each year. This equipment is also a vacuum treatment. Because the top space of the treatment chamber is oxygen-free, not only will the new oxide slag not be generated during the purification treatment, but also the alumina produced will be reduced to aluminum, which will greatly reduce metal loss. This is absolutely impossible for FILD, SNIF, ALPUR, PAL and other equipment. At the end of each casting, the equipment is not filled with alumina slag like other equipment. What can be seen is brown particles, which are scraped into the molten aluminum and melted in real time; after being removed, it is slightly agitated to flash silver luster. This shows that the alumina extracted from the aluminum solution is reduced to aluminum.

The invention is also applicable to the purification treatment of other non-ferrous metals, especially copper alloys. During the melting process of copper alloy, its gas absorption and oxidation are more serious than those of aluminum. In the past purification treatment, nitrogen was generally used. Purification treatment with NSV equipment must have significant efficiency and effect. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of the structure of a non-ferrous metal melting and processing device with a multi-chamber structure according to the present invention.

FIG. 2 is a side view of FIG. 1.

FIG. 3 is a plan view of FIG. 2.

FIG. 4 is a cross-sectional view of another structure of a non-ferrous metal melting and processing device with a multi-chamber structure according to the present invention. Fig. 5 is a sectional view of the structure of a non-ferrous metal melting and processing device with a single chamber structure according to the present invention.

Fig. 6 is a side view of Fig. 5.

7 is a cross-sectional view of another structure of a non-ferrous metal melting and processing device with a single chamber structure according to the present invention. FIG. 8 is a sectional view of the structure of the non-ferrous metal melting and processing device without a chamber structure according to the present invention. DETAILED DESCRIPTION Example 1

The combination of bubble adsorption (N) and vacuum negative pressure (V) of the purified gas to generate an efficient and environmentally friendly purification function is the technical basis and core of the present invention, and is also a technical feature of the present invention that is different from other types of purification methods.

Generally, the processing chamber of the bubble adsorption purification equipment is closed or semi-closed, so when the purification bubbles rise from the bottom, the impurities in the aluminum liquid, including hydrogen and oxide slag, rise to the liquid surface and enter the top space of the processing chamber. As it gathers there, it will soon form a saturated state and generate pressure, which will form resistance to the impurities that continue to run out of the aluminum liquid. The concentration of impurities in the upper aluminum liquid will also increase, which will definitely weaken the purification efficiency. In order to improve the purification efficiency, European and American experts often work on chemical methods and chemical agents, so that the efficiency is not much improved, but environmental protection problems of one kind or another occur.

If the pressure in the headspace of the processing chamber returns to normal, the purification resistance generated by it can be eliminated. If the pressure in the headspace of the processing chamber is negative, greater attraction will be generated, thereby improving the purification ability of the purification bubbles. When performing a vacuum bubble test, you can see that the vacuum (V) negative pressure will suck out the hydrogen contained in the aluminum liquid. Moreover, it is known from the principle of vacuum heat treatment that vacuum treatment can not only prevent the hot metal from oxidizing, but also reduce the metal in the metal oxide.

However, if only the method of vacuum negative pressure is used, it is not suitable because, on the one hand, it has a greater effect on the surface layer of the metal liquid, and has little effect on the bottom layer; on the other hand, the efficiency is worse; on the other hand, the specific operation There are also many problems that are difficult to use in actual production. Therefore, to this day, no successful example has been found in the actual production of vacuum treatment.

In the method of the present invention, after the non-ferrous metal melt (aluminum liquid in this example) enters the processing chamber of the non-ferrous metal melting and processing device, the vacuum pump is started, and the aluminum liquid is pulled by the vacuum negative pressure; at the same time, the purified gas ( In this example, nitrogen) enters the melt through the purge gas diffusion plate at the bottom of the device. The surface of the molten aluminum rolls because of the nitrogen bubbles rising from the bottom. When the nitrogen bubbles rise in the aluminum liquid of the processing chamber, the impurities in the aluminum liquid are adsorbed and captured along the way, including hydrogen and oxides. The surface tension of the molten aluminum is weakened due to the rolling of the aluminum wave. The nitrogen gas bubbles entrain hydrogen and oxides, quickly break through the surface of the molten aluminum, and are sucked into the top space of the processing chamber, and are discharged out of the equipment through the vacuum cover, the exhaust pipe, the cooler, and the vacuum pump. After the aluminum liquid is pumped up, a vortex (Spiral) is formed along the ® wall of the processing chamber, and it is regularly laid down. On the one hand, the vortex plane and the nitrogen bubble rising from the bottom are almost 90%. Contact makes the contact comprehensive and even. On the other hand, due to the effect of centrifugal force, aluminum molecules with a higher density are dropped to the periphery of the vortex. Lighter impurities, including hydrogen and alumina slag, are squeezed into the center of the vortex by aluminum molecules with a larger mass. The surface of the molten aluminum is carried by the nitrogen bubbles rising from the bottom to further enhance the purification effect. The method of the present invention uses nitrogen (N) as a purification carrier, not only because it is cheap, but also mainly because it is harmless to the environment and the health of the operator, and is environmentally friendly. This equipment can also use chlorine (C1) gas and argon (Ar) gas as purification gas, and even add fluorine-containing chlorine-containing purification agent, which can improve the purification efficiency, but this is either too costly or has serious environmental protection problems Therefore, the use of this equipment is discouraged and the use of chlorine gas is discouraged. The designer believes that as long as nitrogen (N) is used as a purification carrier, as long as it is combined with vacuum (V) negative pressure, a very ideal purification state can be achieved. If it is still insufficient, users can increase the capacity of the equipment, or slow down the casting speed to increase the processing time, or add a trough type equipment to the trough, which can improve the purification efficiency and purification effect.

The combination of nitrogen (N) bubble adsorption and vacuum (V) negative pressure is a qualitative leap in the purification efficiency of the equipment. Moreover, it also solves the environmental protection problems that other purification equipment cannot overcome, and greatly saves metal loss and production costs, and also makes the purification more comprehensive, more uniform, and better efficiency.

The equipment for implementing the above method may have various structural forms. Figs. 1 to 3 show an optimal structural form, which is a multi-chamber structure. As shown in the figure, the multi-chamber structure non-ferrous metal melting and processing device 12 is provided. There is a shell 1201, and the inner wall of the shell is lined with refractory mud lining 1210. The inner space of the shell is longitudinally divided into a cleaning chamber 1202 and a processing chamber 1203. The cleaning chamber is used to store the cleaned melt, and the upper hinge frame 1214 passes through it. The hinge shaft 1212 is connected to the clean room furnace cover 1211. The processing chamber is used for purifying the molten metal, and a water-cooled furnace cover 1218 is installed above the hinge shaft 1217 mounted on the hinge frame 1216, and the ceiling shaft 1220 and bearings are mounted on the ceiling bracket 1219. 1221 Sprockets 1222, 1223, 1224 are equipped with a transmission chain 1225 and a hanging chain 1226 connected to the water-cooled furnace cover. The water-cooled furnace cover can be opened by the above sprocket device, or it can be manually turned on the furnace cover. Arm 1213 is manually opened. A vacuum chamber 1204 is provided above the water-cooled furnace lid, which is used to create a vacuum above the melt. The vacuum chamber is provided with a vacuum device 20 for generating a vacuum, which may be a vacuum pump or other vacuum machinery. The vacuum chamber communicates with the processing chamber, and a vacuum cover 1215 is installed on the top of the vacuum chamber. A heater 1205 is installed in each of the processing room and the clean room. In this example, the heater is an electric heating rod. The electric heating rod can be a vertical hanging type as shown in FIG. 1, that is, the upper end is connected to two furnace covers. Part of it is directly hung in the processing room and the clean room. It can also be horizontally embedded as shown in Figure 4, that is, the extension of the electric heating rod is horizontally embedded in the refractory lining of the furnace cavity as required. Regardless of the form, this electric heating rod is an internal heating type or a direct heating type. Because its diameter is only 30mm and it is directly inserted into the metal liquid, it is easy to use, and the heat it emits is all absorbed by the aluminum liquid. Therefore, the use of this electric heating rod is preferred. The bottom of the shell is lined with refractory bricks 1227 and 1228. The upper part of the refractory bricks is equipped with a purification gas diffusion plate 1206, which is connected to the air pump. The diffuser plate can also use a bell-shaped diffuser tube as in Example 2 or other various rotors. The housing is provided with a metal liquid inlet 1207 and a metal liquid outlet 1208, and a vacuum glass 1209 is installed on the vacuum chamber to observe the liquid level on the surface of the aluminum liquid for reference when adjusting the vacuum degree.

The equipment can also be coated with alumina beads in the processing room and clean room. Alumina beads have the function of adsorbing and filtering impurities. You can also attach a filter box with a ceramic filter plate at the exit of the clean room to filter aluminum. Impurities in the liquid. Although these have a positive effect on the quality of the molten aluminum, they are only subsidiary to the entire equipment. Users can decide whether it is necessary to install according to specific needs.

The working principle of this equipment can be seen in Figure 1. After the molten aluminum enters into the processing chamber 1203 from the tangential inlet 1229 of the processing chamber, the vacuum machine 20 is turned on, the molten aluminum is pulled up for vacuum processing, and then a vortex is formed along the circumferential wall, spiraling down. The purified aluminum liquid enters the clean room 1202 through the bottom passage, and then flows into the casting tank through the clean room liquid outlet 1230 for casting. Example 2

The equipment for implementing the purification method of the present invention may also be a single-chamber structure shown in FIGS. 5 to 7. As shown in FIG. 5 and FIG. 6, the non-ferrous metal melting and processing device 11a with a single-chamber structure is provided with a shell llai, and the inner wall of the shell is affixed There is a refractory plate lias, the inner space of the shell constitutes a processing chamber lla2, the upper part of the shell is equipped with a vacuum cover lla3 connected to a vacuum machine, the bottom of the shell is equipped with a purification gas diffusion plate lla4, and the bottom of the shell is equipped with a shutter lla9, with metal on both sides thereof The liquid inlet lias and the metal liquid outlet lla6 are equipped with a peep mirror lla7 on the vacuum cover.

This device is a simpler device for continuous or semi-continuous casting. If conditions permit, flow channel NSV devices can also be added with eddy current function. If the conditions are not acceptable, it is not necessary to arrange it; but in order to avoid the aluminum liquid being short-circuited after the aluminum liquid is pumped up, it will directly flow out without vacuum treatment, and a shutter should be installed in the device.

The aluminum liquid flows in from the metal liquid inlet, rises through the gate, flows to the metal liquid outlet, inputs nitrogen, and starts a vacuum pump for purification treatment. The sight glass is used to observe the water level on the surface of the molten aluminum to adjust the vacuum. In order to improve the purification effect, the length of the device should be increased as much as possible.

A non-ferrous metal melting and processing device with a single-chamber structure is shown in Fig. 7. This device can be used for discontinuous casting. The device lib is provided with a cover llbi, a vacuum cover llb2 and a sight glass llb3 on the top of the cover, a base llb4 on the bottom, a crucible libs inside the cover, a bell-shaped purification gas diffusion tube llb6 on the bottom of the crucible, and a crucible Also equipped with a heater llb7.

The aluminum liquid to be processed is loaded with a crucible or the like and placed in an outer cover for processing. The device is generally not limited by the processing time and can achieve the best purification effect. The device must be equipped with an electric heating device to prevent the molten aluminum from solidifying due to the long processing time. It uses a bell-shaped purge gas diffusion tube connected to the outer cover, and various types of rotating rotors can also be used to improve the degassing efficiency. The sight glass is used to observe the water level on the surface of the molten aluminum to adjust the vacuum. Example 3

Furthermore, the equipment for implementing the purification method of the present invention may also have a single-chamber structure as shown in FIG. .

The device is directly used on various stoves such as electric induction furnaces or holding furnaces, and is covered with a bell-shaped purification gas diffusion tube to spray nitrogen (N) gas; various types of rotating rotors can also be used to improve Degassing Rate. There is no need to install an electric heating rod, because the stove itself has a heating function (equivalent to an external heating type). A vacuum cover (V) is necessary so that it can be combined with nitrogen bubbles to purify the metal liquid.

The device and the device l ib are the same, and are not limited by the processing time, and the processing effect is ideal.

The present invention is not limited to the above-mentioned embodiments, any method and related equipment for purifying non-ferrous metal melt by combining purification gas adsorption and vacuum suction, and equivalent transformation methods related thereto will fall within the scope of the invention Inside.

Claims

Request for Rights

1. A method for purifying a non-ferrous metal melt, comprising purifying gas through the non-ferrous metal melt from bottom to top to perform adsorption purification, characterized in that, while the gas is adsorbed and purified, a vacuum is evacuated above the non-ferrous metal melt, A negative pressure attraction to the melt is formed.

The method for purifying a non-ferrous metal melt according to claim 1, wherein the purge gas is an inert gas.

The method for purifying a non-ferrous metal melt according to claim 2, wherein the purifying gas is preferably nitrogen.

4. The device for realizing the method for purifying the non-ferrous metal melt according to claim 1, characterized in that the device comprises a non-ferrous metal melting and processing device (10) and a vacuum device (20), wherein the vacuum device and the non-ferrous metal melt and The space above the melt in the processing device is connected.

The purification device for the non-ferrous metal melt according to claim 4, characterized in that the non-ferrous metal melting and processing device (10) can be a single-chamber structure, a multi-chamber structure or a non-chamber structure.

The purification equipment for non-ferrous metal melt according to claim 5, characterized in that the single-chamber structure non-ferrous metal melting and processing device (11a) is provided with a casing (llai), and the inner space of the casing constitutes a processing chamber (lla) ₂ ), the upper part of the housing is equipped with a vacuum cover (lias) connected to the vacuum machine, the bottom of the housing is equipped with a purification gas diffusion plate (lla4), the bottom of the housing is equipped with a shutter lla ₉ , and metal liquid inlets (lias) are provided on both sides thereof And metal liquid outlet (lla6), the vacuum cover is equipped with a sight glass (lla7).

The purification equipment for non-ferrous metal melt according to claim 5, characterized in that the single-chamber structure non-ferrous metal melting and processing device (lib) is provided with an outer cover (llbi), and a vacuum cover (llb2) is provided on the top of the outer cover. ) And peepers (libs), with a base (llb4) at the bottom, a crucible (libs) inside the cover, a bell-shaped purification gas diffusion tube (llb6) at the bottom of the crucible, and a heater inside the crucible (Llb ₇ ).

The purification device for non-ferrous metal melt according to claim 5, characterized in that the multi-chamber structure non-ferrous metal melting and processing device (12) is provided with a casing (121), and the inner space of the casing is longitudinally divided into clean Chamber (122) and processing chamber (123), a vacuum chamber (124) is arranged above the processing chamber, a heater (125) is installed in the processing chamber and a clean room, a purifying gas diffusion plate (126) is arranged at the bottom of the shell, and the shell is Equipped with metal liquid inlet (127) and metal liquid outlet (128), with a sight glass in the vacuum chamber

(129).

The purification device for non-ferrous metal melt according to claim 5, characterized in that the non-chamber structure non-ferrous metal melting and processing device (12) is provided with a vacuum cover (121) and a sight glass on the upper part of the melting furnace. (122), and a bell-shaped purge gas diffusion tube (123) is installed in the furnace.