KR20130020675A - Method for producing aluminium by metallothermic reduction of trichloride with magnesium and apparatus for carrying out said method - Google Patents

Abstract

An aluminum accommodating method is provided by metal thermal magnesium recovery of aluminum trichloride at a temperature of 900 ° C. to 1150 ° C. and a flow of inert gas at a total pressure of 0.01 to 5 atm, the mass correlation of aluminum chloride and magnesium in the parent mixture being 3.69: 1.00 The process is realized in a cylindrical reactor with a thin walled attachment 6 made of ceramic and located inside the reactor. The reactor is provided with a conical bottom portion. A cauldron-evaporator of magnesium into the flow of inert gas is mounted at the front of the reactor, and behind the reactor there is a unit for separating liquid magnesium from the remaining mixture of magnesium and aluminum chloride, all components of the apparatus being made of fireproof material. Lining. The technical result is increased efficiency in exchange for a guaranteed continuous process of recovery and the best ecological properties.

Description

METHOD FOR PRODUCING ALUMINIUM BY METALLOTHERMIC REDUCTION OF TRICHLORIDE WITH MAGNESIUM AND APPARATUS FOR CARRYING OUT SAID METHOD}

The present invention relates to nonferrous metallurgy, and more particularly to aluminum production technology.

In non-ferrous metallurgy, the method of so-called Hero-Hall, which is the electrolysis of cryolitho-alumina melt, is used to produce aluminum. Electrochemical devices and cells are particularly characterized by a rather low factor indicator of the useful volume consumed when the operation is registered only on the surface of the electrode-electrolyte, not all through the entire volume of the reactor in chemical technology.

Only one electrode, the cathode, is responsible for the total amount of useful work performed when the process is performed according to the method of eru-hole. As a result, the cell is characterized by a rather low productivity per cell, only 3-4 tons per 24 hour cycle. Thus, plants producing aluminum have hundreds and thousands of cells, which occupy a vast area and consume significant investment during drying.

The cell is not sealed by the structural characteristics of the cell and the overall process is sodium (natrii), aluminum and hydrogen fluorides, carcinogenic polyaromatics compounds, bulk greenhouse gases, carbon dioxide and especially perfluorocarbons ( perfluorinecarbon) into the atmosphere. All of the above is considered, and the production of aluminum by electrolysis of the Cryriso-aluminum melt is quite outdated, which is the frequency or physical occurrence of aluminum in the earth's crust (leading place among the metals). Because it does not correspond to the only set of structural and technical characteristics.

Along the scheme there has been a conventional solution to the problem of aluminum acceptance based on metal thermal methodology by recovery with potassium from aluminum chloride (F. Wohler, 1828) or sodium (S'K. Deville, 1854):

AlCl ₃ + 3M = 3MCl + Al (1),

Here, M is an alkali metal.

However, when alkali metal is used corresponding to Scheme 1, the consumption of metal and power is very high. When associated with potassium, 4.33 kg of alkali metal and 35 kW / h of power are consumed to recover 1 kg of aluminum. For sodium, 2,555 kg of metal and 25,5 kw / h of power are needed to recover 1 kg of aluminum.

For other common similar methods. yen. N. N. Beketov's proposal is the most practical. Accordingly, aluminum can be received through the recovery of aluminum by magnesium from aluminum fluoride or cryolite, which is a component of Greenlandic cryolithionite.

2 (3NaF x AlF ₃ ) + 3Mg = 6NaF + 3MgF ₂ + 2Al (2).

Fluoride is a more difficult compound, and the devices as well as the recovery process are more complicated to implement this method. In addition, the only deposits of Greenlandic Cryolith were discharged from the same dates as in the nineteenth century.

The closest standard for this method is the production of metal titanium as a result of the recovery of metal titanium by metal magnesium from tetrachloride.

TiCl ₄ + 2Mg = 2MgCl ₂ + Ti (3)

This process involves the incorporation of titanium chlorides of different valences into the reaction state, so that the relations of the reactions are in different states: titanium chloride in the gas phase, magnesium chloride and magnesium as liquids, whereas as solids. It is in titanium. As a result, this method requires depressurizing the device from time to time to extract titanium, which reduces the productivity of the process and degrades the ecological properties.

Crawl W. Kroll W.J.US 2205854 1940

Crawl W. Kroll W.J.Trance. Trans. Electrochem. Soc., Vol. 78, 1940, 35. V. a. Metallusia Titana, V.A. Garmata. Mallallurgia titana.M., Metalallurgia, 1968, 643 s. a. yen. A.N. Zelichman, G. a. G.A. Meerson. Metallurgia redkich metallov, M., Metallurgia, 1973, 607 c. Spravotchnik chemica // Pod red. B.P. B.P. Nikolskogo, t II, Chemia, M., 1964, 1168 s. M. M. Giua, Istoria chemie, Mir, M., 1975, 477 s M. M. M.M. Vetukov, A. M. A.M. Tsiplakov, S. yen. S.N. Schkolnicov. Electro-Matalusia Alumina Eye Magnia. M. (trometallurgia aluminia i magnia. M.), Metalallurgia, 1987, 320 s K. K. Grjotheim, Kew. Q. Zhuxian. Molten Salt Technology, VII, Shenyang, China, 1991, 435. V. a. V.A. Lebedev, V.I. Sedykh. Metalallurgia magnia, Irkutsk, 2010, 175 s. a. children. A.I. Begunov. Problems modernizathii aluminum electrolizerov, Irkutsk, 2000, 105 s. Crawl W. Kroll W.J.Trans. Electro shock. Ectrochem. Soc., 1947, no. 89, s. 41 Crawl W. Kroll W.J. Metals, 1955, Vol. 5, 9-10, 336. V. blood. Masovets. Electrolizerov aluminia. ONTI-NKTP, SSSR, 1938, 345 s.

The technical consequences of introducing the present invention are higher productivity by the continuity of the recovery process and improved ecological properties by providing device closure.

Technically, this object is met by using a reaction of metal heat recovery of aluminum trichloride with magnesium.

2AlCL _{3 (g)} + 3Mg _(g) = 3MgCl _{2 (1)} + 2Al ₍₁₎ (4),

Here, << g >> is an indication of the gas phase while << l >> is an indication of the liquid state. Thus, according to Scheme (4), the parent substance is introduced as a process as a gaseous substance and the resulting product, which is aluminum and magnesium chloride, is released as a molten liquid substance. The recovery is carried out with a flow of inert gas at a temperature of 900 ° C. to 1150 ° C. and a total pressure of 0.01 to 5 atm., With the proportion of aluminum chloride and metal magnesium mass in the initial mixture correspondingly being 3.69 to 1.00. In this case, the consumption of magnesium would be only 1.35 kg per kg of aluminum, while the power requirement for electrolytic magnesium would be about 17.9 kW / h per kg of aluminum. The results are further improved when magnesium is employed in the metal thermal manner, that is, when magnesium is first recovered from dolomite by ferrosilicon according to Pigeon's technique (V. VALebedev, V. I. Veddykh, Metallurgy of Magnesium, Irkutsk, 2010, 149). According to Scheme (4), the total consumption of energy in this case will not exceed 13 kWh per kg of aluminum, which is similar to the consumption value for the Eru-Hole method, which is very useful at the stage of generating the magnesium-thermal mode of aluminum production. Can be considered as an indication.

However, recovery of aluminum from trichloride by magnesium according to Scheme (4) is an independent scientific and engineering problem. Scheme (4), which is the basis of the present invention, is realized much simpler than Scheme (3) as a standard for magnesium-thermal recovery of titanium. However, it can be seen as ironic, but higher temperatures and pressures are required to produce aluminum as a result of recovery of aluminum by magnesium from trichloride.

In fact, magnesium as a recovery agent has a boiling point temperature of 1103 ° C. to 1107 ° C. (the pressure of the steam forms 1 atmosphere), and the melting temperature of magnesium is 651 ° C. For another participant of Scheme (4), aluminum melts at 660 ° C. A particularly wide range of liquid states is characteristic for aluminum with a boiling point of 2497 ° C. Aluminum does not actually evaporate at the boiling point of magnesium (1107 ° C). Magnesium chloride melts at 708 ° C. to 714 ° C. and boils at temperatures ranging from 1412 ° C. to 1417 ° C. to have a relatively broad liquid state. And finally, aluminum trichloride may be sublimed at a temperature of 179.7 ° C. and not present in the liquid state at normal atmospheric pressure. Thus, the parent substance, aluminum trichloride and magnesium, is in the gas phase at temperatures above 1107 ° C. and the metal aluminum and magnesium chloride are in the liquid state at the same temperature, which is convenient to construct continuously high and efficient production. Situation.

As evidenced by the results of thermodynamic calculations, the process of Scheme (4) is characterized by an enthalpy value of -240 kJ and Gibbs energy value of -210 kJ at a temperature of 1300 K (1027 ° C). do. This means that the process works spontaneously to dissipate large amounts of heat. However, very high possible rates of recovery process should be taken with regard to the high reactivity of aluminum chloride and gaseous metal magnesium, which are in the gas phase and superheated to about 900 ° C. during partial dissociation into monochloride. In addition, the single reaction equation (4) corresponding to the gaseous and liquid state following the Le Chatelier law and the second law of thermodynamics, with the indexes << g >> and << l >> at higher pressures, shifts considerably to the right Will have a balanced balance. For its kinetics, the reaction can take place in an explosion, allowing to control the rates of the parent element, aluminum chloride and magnesium and be fed to the individual flows of inert gas at lower temperatures than supported in the reactor.

The recovery process can occur at a temperature of 900 ° C. in this state because the saturated vapor tension of magnesium is conceivable and forms, for example, about 0.19 at 927 ° C. At the same time it is not reasonable to raise the temperature considerably above the boiling point of magnesium (1103 ° C to 1107 ° C), since this temperature rise entails a much higher rate value of the process, so 1150 ° C can be set as the highest threshold. have.

The total pressure of the gas phase in the reactor is assigned within 0.01 to 5.0 at the optimum partial pressure of aluminum chloride and magnesium experimentally identical. It is preferred to be oriented at the upper value of the total pressure, but to avoid reaching its explosion limit.

For the composition of the gas mixture supplied for recovery, it should correspond to the stoichiometric ratio of the mass contained in Scheme (4) and form 3.69: 1 for the aluminum trichloride and magnesium mass flow fed to the reactor.

The practicality of the claimed invention is assured because there is a similar formation of titanium from tetrachloride in a magnesium-thermal manner. In addition, the claimed mode of receiving aluminum is much simpler. Magnesium also has more negative metal than aluminum. The power input can be rather smaller when magnesium is received from the dolomite by its recovery in combination with conventional methods of magnesium chloride electrolysis. Moreover, the process is a self production process.

The mode of using vapor phase aluminum chloride and magnesium as the parent material for the acceptance of the resulting product of magnesium chloride and aluminum as liquids can be realized in the sealing device. It is automation friendly and does not require the application of any mechanical device or any manual labor input to provide a process. The highly recognized ecological characteristics of the present invention with respect to the application of the sealing device are apparent. The possibility to design a device with high productivity, low configuration and production inputs per reactor is one of the significant advantages of the modes provided.

The practicality of the present invention is demonstrated by the presence of strong and effective industries of titanium extraction from tetrachloride using magnesium thermal methodology and by the smoothly realized recovery of zirconium and hafnium from chloride by the progress of the magnesium thermal process.

In connection with the magnesium thermal mode of receiving titanium, a cylindrical vessel of steel was initially used as a recovery device. The cylindrical container of steel is made, for example, of chromium-nickel steel lined with molybdenum plates. Later, the lining is made of low-carbon steel. The process is realized at a temperature lower than the metal melting temperature, so titanium is contained in a solid-phase state such as a sponge. The reactor will be cooled to extract the sponge. Thus, the whole process is inevitably characterized as a periodic process that requires manual labor input in its own sequence, reduces reactor efficiency, raises energy input and degrades the ecological characteristics of manufacturing.

In the claimed invention, which is intended for the metal heat recovery of aluminum by magnesium, the process takes place at higher temperatures reaching 1100 ° C to 1150 ° C. In this state, the recovered product aluminum, and magnesium chloride, are in the liquid state and flow down into the bottom portion of the reactor. The melting temperature of aluminum is 660 ° C. while the melting temperature of magnesium chloride is 708 ° C. to 714 ° C. and has a boiling point temperature of 2497 ° C. and 1412 ° C. to 1417 ° C., respectively. To this end, the top of the reactor is made cylindrical to increase the useful volume of the reactor, while the bottom portion of the reactor is conical to collect liquid aluminum and magnesium chloride.

Most reaction zones are made hollow and gaseous aluminum chloride and magnesium are introduced to mix them more completely, and the volume adjacent to the conical part is filled with a thin walled hollow ceramic piece of lathzig ring type attachment. The use of deposits accelerates the process of condensation and drops the fusion to form aluminum and magnesium chloride.

The flow of inert gas is connected to the reactor and to the apparatus for separating liquid magnesium from the cauldron vaporized magnesium and the residue mixture of magnesium and aluminum chloride vapor. Both the cauldron, which is a magnesium evaporator, and the device for separating liquid magnesium are integral parts of the device. Although rather close, they are located individually from the reactor.

The reaction of aluminum recovery from its chloride with magnesium in the gas phase is exothermic and is accompanied by the release of a large amount of heat, the process being a self-producing process. In order to closely control the rate and temperature of recovery, the reactor and the magnesium separation unit are equipped with a system of boiling water cooling to evaporate.

Fluid states (liquid and gas) are used in the present invention under consideration. The fluid state reacts in turbulent flow at high temperatures to provide for high efficiency of the process.

In addition, the financial expenditure intended for the production of manufacturing equipment is lowered along with the financial expenditure for maintenance of the equipment.

1 is a general view of a reactor.
In FIG. 2 a cauldron-evaporator can be seen.
3 shows the device of separation.
All of these are vertical cross sections.

The reactor (FIG. 1) is made as a cylinder of steel 1 in which a recovered product, ie aluminum and magnesium chloride, is converted into a conical bottom portion 2 intended for collection. The pulse bottom 3 is located between the cylinder and the cone part. The reactor is sealed with a lid 4. All inner surfaces of the reactor are lined with refractory materials 5 such as magnesite, graphite and other inert stuffs.

An attachment 6 made of a thin walled ceramic of the raspich ring type and which is typically applied to chemical absorption techniques is disposed on the pulse bottom 3. The attachment is made of a fire retardant material such as magnesite, carbonitride, and the like.

Nozzles and injectors 7 and 8 fixed in the upper hollow portions of the reactor facing and facing each other in the circumference of the horizontal section of the reaction zone are used to introduce parent materials of gaseous aluminum chloride and magnesium metal (gas) into the reactor. do. The recovered aluminum 9 and magnesium chloride 10 are collected in the conical portion 2 of the reactor such that magnesium chloride 12 leaks through the tap hole 11 and aluminum 13 is collected in the pan 14. . There is a branch pipe 15 installed in the lid of the reactor to remove the mixture of aluminum chloride and magnesium not contained in the reaction from the reactor.

The cauldron-evaporator (FIG. 2) is a hemispherical steel 16 sealed with a lid 17, all lined with the same material as the reactor. Magnesium is introduced into the cauldron in liquid form. The electric heater 18 is immersed into the metal. It can be formed as a set of silicon carbide rods and surrounded by a protective magnesite coating. Inert gas (argon or nitrogen) is fed into the cauldron-evaporator. In its vapor state magnesium is directed into the reactor with an inert gas. The cauldron-evaporator is equipped with a system of divergent water cooling, such as the other elements of the device given in FIGS. 1 and 3.

The separation device (FIG. 3) intended for the separation of liquid magnesium from the remaining mixture with aluminum chloride (FIG. 3) is a smaller sized reactor lined with fireproof ceramic 19. Branch pipe 20 supplies a gas mixture into the device and fluid magnesium condenses and collects in the bottom portion of the device. Residual aluminum chloride, which is not included in the reaction, is removed from the apparatus through another branch pipe 21 and the residual aluminum chloride is recovered back into the reactor. The device of separation, such as a reactor, is equipped with a lock unit 22 and a system 23 of divergent cooling. The condensate of magnesium is returned back into the cauldron-evaporator and then further into the reactor.

The apparatus continuously feeds the gaseous magnesium and aluminum chloride vapors to the reactor which are accommodated in a single cauldron evaporator or in a set of such evaporators. Aluminum chloride and gaseous magnesium chloride are fed into the reactor in the incoming turbulent flow of inert gas, which is a deliverer and is provided for ideal conditions to contact the reaction particles, remove the diffusion barrier and enable a high speed recovery process and Delivered. In order to achieve a higher withdrawal rate of the final product, namely aluminum and magnesium chloride, it is necessary to use a larger number and larger surface of the active center of liquid phase formation from the reactor. This is achieved as a result of using the aforementioned thin walled and non-uniform attachments of the Ruschig ring type made of magnesite. The aluminum 13 released from the reactor in continuous or periodic mode is protected by an excellent coating of molten magnesium chloride 12. Separation of the recovered product is feasible with ease. For example, as the drop in temperature drops to 680 ° C. to 700 ° C., the coating of magnesium chloride transforms the state of magnesium chloride into a solid state while liquid aluminum can be easily directed to be included in other technical tasks.

Separation devices intended for the separation of aluminum chloride from magnesium in their residue gaseous mixture operate as a result of the pressure drop in the system and the drop in temperature below the magnesium boiling temperature. If the condensate is sufficiently washed, the liquid magnesium in the form of condensate is directed to the cauldron to be purified or evaporated and then further to the reactor.

Both the reactor and the separation device are equipped with a system of water divergent cooling to provide a high but controllable recovery rate. The working principle of such equipment, used in many fields of technology, including metallurgy, is well-known and finely tuned. The system of inert gas circulation is also very controllable both in chemical technology and in rare metallurgy.

The use of the technique of the present invention requires the gas phase of aluminum chloride to be introduced through the injector 7 into the top of the cylinder of steel 1 associated with the reactor (FIG. 1). Vapor or vapor phase magnesium mixed with the inert gas introduces the same way back-flow through the injector 8. This mixing is prepared in advance in the cauldron-evaporator (FIG. 2). The parent agent, ie inert gas (eg argon) and liquid magnesium, is introduced there separately, while the two-component flow of gaseous magnesium and inert gas is removed from the cauldron and sent to the reactor (FIG. 1). (FIG. 1).

The liquid aluminum and magnesium chloride formed condensate and coalesce the attachment surface 6 (FIG. 1) and fall slightly into the conical part of the reactor and further through the tapped holes 11 the liquid aluminum and magnesium chloride are recovered product, namely aluminum (13). ) And magnesium chloride 12 into the pan 14. The residue gaseous mixture is extracted through branch pipe 15 (FIG. 1). This mixture is introduced into the separation unit via pipe 20 (FIG. 3), and then the magnesium removed from the separation unit via lock unit 22 is returned back into the cauldron-evaporator while the gas phase is injector 7 ( Upon recovery back into the reactor through FIG. 1), aluminum chloride is extracted through the pipe 21.

Industrial availability

The practicality of the present invention submitted is without question and is due to the fact that similar but very much more complex processes of magnesium-heat recovery of titanium from its tetrachloride are available and widely used in the USA, the Russian Federation and some countries of the UIS. It is confirmed.

The present invention has been provided for many advantages regarding the technology and new equipment of aluminum acceptance. This is a low financial expense and undetermined high unit efficiency of the device for manufacturing new manufacturing equipment. Correct the sealing and ecological safety of the preparation. Heavy manual labor is excluded from manufacturing and conceivable of complete automation of the process. The aluminum recovery in the device occurs with a significant amount of thermochemical and heating effects and is actually without self-producing mode, without any energy consumption from the outside.

Claims (3)

A method of producing aluminum by metal heat recovery of aluminum from aluminum trichloride to magnesium in a flow of inert gas,
Characterized in that the parent substance is introduced into the process as a gaseous substance and the resulting product, aluminum and magnesium chloride, is discharged as a molten liquid substance,
Aluminum production method.
The method of claim 1,
The recovery was at a temperature of 900 ° C. to 1150 ° C. and 0.01 at. To a total pressure of from 5.00 at, characterized in that the mass correlation of aluminum chloride and magnesium in the parent mix is 3.69: 1.00,
Aluminum production method.
An apparatus for performing the method claimed in claim 1, comprising:
1. A device comprising a cylindrical reactor having a thin wall attachment made of ceramic, wherein the thin wall attachment is located inside the reactor having a conical bottom part.
The reactor is equipped with a cauldron-evaporator of magnesium into a flow of inert gas, a device for liquid magnesium is separated from the residual mixture and aluminum chloride, the cauldron-evaporator is installed in front of the reactor, and the separation device is Disposed after the reactor and all of the components of the apparatus are lined inside with a fire retardant material,
Device.

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