CN106756068A - A kind of method that aluminium is extracted in the ash from aluminium - Google Patents

Abstract

The present invention relates to the technical field of recycled metals and the field of waste miscellaneous aluminum regeneration treatment, and in particular provides a method for extracting metal aluminum from a large amount of aluminum ash produced in the waste miscellaneous aluminum regeneration process; the process scheme adopted in the present invention is: application The method of low-valent chloride-molten salt vacuum treatment is used to treat the secondary aluminum ash after thermal recovery and/or conventional cold treatment, that is, the secondary aluminum ash is used as raw material, and the metal aluminum is extracted by low-valent chloride after flux treatment. The method realizes the extraction of metal aluminum to the greatest extent; the advantage of the present invention is that the melting process is easy to operate, the raw material is cheap and easy to obtain, and the low-price chloride used to extract metal aluminum can be recycled without producing substances that pollute the environment ; The whole process is carried out in a vacuum, the product is of high purity and has no impact on the environment, and the purity of recycled metal aluminum can reach 99.99%.

Description

A method of extracting aluminum from aluminum ash

technical field

The invention relates to the technical field of recycled metals and the field of waste and miscellaneous aluminum regeneration treatment, and in particular provides a method for extracting metallic aluminum from a large amount of aluminum ash generated during the waste and miscellaneous aluminum regeneration process.

Background technique

Aluminum ash (also known as aluminum slag ash or aluminum slag) is a kind of scum produced in the primary and secondary aluminum industrial production, which is in the form of loose ash. The aluminum ash produced during the processing of liquid primary aluminum generally contains 30-70% metallic aluminum, and is usually called white ash or primary aluminum ash. The waste produced by the secondary aluminum industry usually contains 5-30% metallic aluminum and a large amount of soluble dross, commonly known as black ash. Aluminum metal mainly exists under the coating of alumina and aluminum nitride. Aluminum ash is a substance harmful to the environment. Directly discarding it will cause environmental pollution. Aluminum ash is a renewable resource with comprehensive utilization value, from which secondary resources such as aluminum, salt and alumina can be recovered, and can also be used as Raw materials for refractory materials, road and building materials, steelmaking desulfurizers, etc.

In recent years, the extraction of metallic aluminum from aluminum ash has attracted more and more attention from domestic and foreign aluminum factories. Modern aluminum factories have two ways of dealing with aluminum ash, one is to recycle metal aluminum; the other is to use aluminum ash to produce new valuable products, such as the production of water purifiers, brown corundum, etc. At present, the process of recovering metal aluminum from aluminum ash is divided into salt-added treatment and salt-free treatment according to the presence and absence of salt. The recovery rate can reach 60-70% after conventional hot-state fried ash and cold-state ball milling and sieving, and there are still about 10% of metallic aluminum in the residual aluminum ash.

The present invention is mainly aimed at residual aluminum ash of 20 mesh to 60 mesh and above after hot state fried ash and subsequent cold state ball milling and screening, and it is difficult to extract metal aluminum from this part of aluminum ash by conventional methods. This part of aluminum ash is mostly disposed of by aluminum factories, which has low economic benefits and great environmental impact. With the development of our country's economy, the output of aluminum factories has increased. Choosing a reasonable and effective way to recover and extract aluminum can not only solve the problem of aluminum ash storage, but also bring greater economic benefits to its enterprises.

Looking at home and abroad, foreign literature reports that pure aluminum can be extracted from Al-Si primary alloys by using the aluminum trichloride reaction method, and a large amount of Cu, Fe, Si, Mn, Ni, etc. can be separated. The Institute of Nonferrous Metals of the Soviet Union used low-valent chloride distillation to extract pure aluminum from primary Al-Si alloys. In 1939, Wilmot discovered low-valent fluoride, and in 1942, Vaais discovered low-valent chloride and bromide. So far, low-valent halogen compounds, especially low-valent chlorides, have been used in refining Al-Si alloys or have been effective. The principle of this method is that the compound of trivalent aluminum reacts with aluminum alloy at high temperature to form low-valent aluminum compound with high volatility, and the low-valent aluminum compound decomposes into metal aluminum and trivalent aluminum compound at low temperature. Other components in the alloy seldom react in this way. In this way, the aluminum metal is separated from the other components of the alloy. However, so far, there is no report on the extraction of aluminum from aluminum ash using low-valent compounds.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for further extracting metallic aluminum from secondary aluminum ash.

The secondary aluminum ash mentioned in the present invention refers to the residual aluminum ash produced after the aluminum ash produced in the aluminum industry is extracted through the traditional aluminum recovery process (such as hot ash frying method, cold treatment recovery method, etc.). In particular, it refers to the residual aluminum ash with a particle size of 20 mesh to 60 mesh and above 60 mesh obtained after successively frying ash in a hot state, then ball milling in a cold state, and sieving. This secondary aluminum ash has been difficult to carry out secondary extraction according to the currently known conventional recovery process.

In order to solve this technical problem, the technological scheme adopted in the present invention is: apply the low-valent chloride-molten salt vacuum treatment method to process the secondary aluminum ash after thermal recovery treatment and/or conventional cold treatment. That is to say, using secondary aluminum ash as raw material, the method of extracting metal aluminum through flux treatment and low-valent chloride can realize the maximum extraction of metal aluminum.

Specifically, the method for extracting aluminum from aluminum ash comprises the following steps:

1) Prepare the raw material, which is the secondary aluminum ash of more than 60 meshes after hot-state fried ash and cold-state ball milling and screening;

2) Prepare molten salt, a mixture of NaCl, KCl and NaF, the mass ratio of NaCl, KCl and NaF is 4~4.5:4~4.5:1~2;

3) Send the secondary aluminum ash in step 1) into the preheating furnace, preheat in the preheating furnace, and preheat the secondary aluminum ash to 300-500°C;

4) Add the molten salt in step 2) into the reaction furnace to melt the molten salt;

5) Transfer the preheated aluminum ash to the reaction furnace, and lock the reaction furnace cover;

6) Vacuumize the reaction furnace until the pressure in the reaction furnace reaches 10-70Pa, and when the temperature reaches 700-1200°C, feed AlCl ₃ gas; AlCl ₃ reacts violently with Al to form AlCl;

7) Volatile AlCl enters the low temperature chamber at a temperature of 400-500°C; AlCl decomposes into AlCl ₃ and Al in the low temperature chamber.

The obtained metal aluminum part is returned to the secondary aluminum melting furnace for melting, and the _AlCl3 gas can be returned for recycling, or the _AlCl3 solid can be recovered after cooling treatment.

The sequence of steps 3) and 4) in the present invention can be optimized and determined according to the respective required time.

The device used in the method is composed of a high-temperature reaction chamber, a low-temperature deposition chamber, a vacuum system, a heating system and the like. The whole process is under vacuum conditions, the aluminum ash is in the molten flux, the Al2O3 film on the surface of the metal aluminum is dissolved by the molten salt, the metal aluminum is exposed to the outside, and the high-valence chlorides react with the high-valence chlorides to form low-valence chlorides and escape the melt. After the valence chloride enters the low temperature chamber, it decomposes into high valence gaseous chloride and metal aluminum deposits in the graphite or alumina tray.

The present invention has the following beneficial effects.

The invention has the advantages that the melting process is easy to operate, the raw material is cheap and easy to obtain, the low-priced chloride used for extracting metal aluminum can be recycled, and no substances polluting the environment are produced. The whole process is carried out in vacuum, the product is of high purity and has no impact on the environment.

The method of the invention avoids the use of carbothermal reduction, does not produce Al ₄ C ₃ affecting the quality of metal aluminum during the reaction process, and can obtain high-quality and high-purity metal aluminum. The purity of metal aluminum recovered by the method of the invention can reach 99.99%.

The invention uses low-valent chloride-molten salt to vacuum-process aluminum ash of more than 60 meshes, so as to realize maximum extraction of metal aluminum. It fills up the technical blank of this type of aluminum ash treatment. The characteristics of the process of the present invention are: 1. fixed aluminum chloride is sublimated at 183 ℃, so the gas AlCl3 is easy to produce; _2. the formation temperature of low-valent chloride is low; AlCl ₃ , Al is densely condensed, and after the gas AlCl ₃ is separated from Al, it is possible to recycle; ④The energy consumption is not much, and the energy required for recycling one kilogram of aluminum is less than two kilowatt-hours. The raw materials are treated with flux, and aluminum is extracted with low-price chloride. The whole process is safe and controllable, easy to operate, simple in equipment required, friendly to the environment, and high in metal yield. The method can also be applied to new aluminum smelting methods such as recycled blast furnace aluminum smelting and electric furnace aluminum smelting to obtain aluminum in aluminum ash.

detailed description

The present invention will be further described below in conjunction with specific examples.

Example 1

A method for extracting aluminum from aluminum ash, comprising the steps of:

1) Prepare the raw material, which is the secondary aluminum ash of more than 60 meshes after hot-state fried ash and cold-state ball milling and screening;

2) Prepare molten salt, a mixture of NaCl, KCl and NaF, the mass ratio of NaCl, KCl and NaF is 4.2:4.2:1.6;

3) Send the secondary aluminum ash in step 1) into the preheating furnace, preheat in the preheating furnace, preheat the secondary aluminum ash to 400°C, and preheat for 30 minutes;

4) Add the molten salt in step 2) into the reaction furnace to melt the molten salt;

5) Transfer the preheated aluminum ash to the reaction furnace, and lock the reaction furnace cover;

6) Vacuumize the reaction furnace until the pressure in the reaction furnace reaches 10Pa, and when the temperature reaches 700°C, feed AlCl ₃ gas; AlCl ₃ reacts violently with Al to form AlCl;

7) Volatile AlCl enters the cryogenic chamber at a temperature of 300°C; AlCl decomposes into AlCl ₃ and Al in the cryogenic chamber.

Example 2

A method for extracting aluminum from aluminum ash, comprising the steps of:

1) Prepare the raw material, which is the secondary aluminum ash of more than 60 meshes after hot-state fried ash and cold-state ball milling and screening;

2) Prepare molten salt, a mixture of NaCl, KCl and NaF, the mass ratio of NaCl, KCl and NaF is 4.5:4.5:1;

3) Send the secondary aluminum ash in step 1) into the preheating furnace, preheat in the preheating furnace, preheat the secondary aluminum ash to 500°C, and preheat for 120 minutes;

4) Add the molten salt in step 2) into the reaction furnace to melt the molten salt;

5) Transfer the preheated aluminum ash to the high-temperature reaction furnace, and lock the reaction furnace cover;

6) Vacuumize the reaction furnace until the pressure in the reaction furnace reaches 50Pa, and when the temperature reaches 900°C, feed AlCl ₃ gas; AlCl ₃ reacts violently with Al to form AlCl;

7) Volatile AlCl enters the cryogenic chamber at a temperature of 500°C; AlCl decomposes into AlCl ₃ and Al in the cryogenic chamber.

Example 3

A method for extracting aluminum from aluminum ash, comprising the steps of:

1) Prepare the raw material, which is the secondary aluminum ash of more than 60 meshes after hot-state fried ash and cold-state ball milling and screening;

2) Prepare molten salt, a mixture of NaCl, KCl and NaF, the mass ratio of NaCl, KCl and NaF is 4:4:2;

3) Send the secondary aluminum ash in step 1) into the preheating furnace, preheat in the preheating furnace, preheat the secondary aluminum ash to 300°C, and preheat for 60 minutes;

4) Add the molten salt in step 2) into the reaction furnace to melt the molten salt;

5) Transfer the preheated aluminum ash to the high-temperature reaction furnace, and lock the reaction furnace cover;

6) Vacuumize the reaction furnace until the pressure in the reaction furnace reaches 70Pa, and when the temperature reaches 1000°C, feed AlCl ₃ gas; AlCl ₃ reacts violently with Al to form AlCl;

7) Volatile AlCl enters the cryogenic chamber at a temperature of 450°C; AlCl decomposes into AlCl ₃ and Al in the cryogenic chamber.

Example 4

A method for extracting aluminum from aluminum ash, comprising the steps of:

1) Prepare the raw material, which is the secondary aluminum ash of more than 60 meshes after hot-state fried ash and cold-state ball milling and screening;

2) Prepare molten salt, a mixture of NaCl, KCl and NaF, the mass ratio of NaCl, KCl and NaF is 4:4:2;

3) Send the secondary aluminum ash in step 1) into the preheating furnace, preheat in the preheating furnace, preheat the secondary aluminum ash to 470°C, and preheat for 80 minutes;

4) Add the molten salt in step 2) into the reaction furnace to melt the molten salt;

5) Transfer the preheated aluminum ash to the high-temperature reaction furnace, and lock the reaction furnace cover;

6) Vacuumize the reaction furnace until the pressure in the reaction furnace reaches 20Pa, and when the temperature reaches 1100°C, feed AlCl ₃ gas; AlCl ₃ reacts violently with Al to form AlCl;

7) Volatile AlCl enters the cryogenic chamber at a temperature of 500°C; AlCl decomposes into AlCl ₃ and Al in the cryogenic chamber.

Example 5

A method for extracting aluminum from aluminum ash, comprising the steps of:

1) Prepare the raw material, which is the secondary aluminum ash of more than 60 meshes after hot-state fried ash and cold-state ball milling and screening;

2) Prepare molten salt, a mixture of NaCl, KCl and NaF, the mass ratio of NaCl, KCl and NaF is 4.5:4.5:1;

3) Send the secondary aluminum ash in step 1) into the preheating furnace, preheat in the preheating furnace, preheat the secondary aluminum ash to 300°C, and preheat for 60 minutes;

4) Add the molten salt in step 2) into the reaction furnace to melt the molten salt;

5) Transfer the preheated aluminum ash to the high-temperature reaction furnace, and lock the reaction furnace cover;

6) Vacuumize the reaction furnace until the pressure in the reaction furnace reaches 60Pa, and when the temperature reaches 900°C, feed AlCl ₃ gas; AlCl ₃ reacts violently with Al to form AlCl;

7) Volatile AlCl enters the cryogenic chamber at a temperature of 400°C; AlCl decomposes into AlCl ₃ and Al in the cryogenic chamber.

Example 6

A method for extracting aluminum from aluminum ash, comprising the steps of:

1) Prepare the raw material, which is the secondary aluminum ash of more than 60 meshes after hot-state fried ash and cold-state ball milling and screening;

2) Prepare molten salt, a mixture of NaCl, KCl and NaF, the mass ratio of NaCl, KCl and NaF is 4:4:2;

3) Send the secondary aluminum ash in step 1) into the preheating furnace, preheat in the preheating furnace, preheat the secondary aluminum ash to 500°C, and preheat for 100 minutes;

4) Add the molten salt in step 2) into the reaction furnace to melt the molten salt;

5) Transfer the preheated aluminum ash to the high-temperature reaction furnace, and lock the reaction furnace cover;

6) Vacuumize the reaction furnace until the pressure in the reaction furnace reaches 40Pa, and when the temperature reaches 750°C, feed AlCl ₃ gas; AlCl ₃ reacts violently with Al to form AlCl;

7) Volatile AlCl enters the cryogenic chamber at a temperature of 350°C; AlCl decomposes into AlCl ₃ and Al in the cryogenic chamber.

Example 7

A method for extracting aluminum from aluminum ash, comprising the steps of:

1) Prepare the raw material, which is the secondary aluminum ash of more than 60 meshes after hot-state fried ash and cold-state ball milling and screening;

2) Prepare molten salt, a mixture of NaCl, KCl and NaF, the mass ratio of NaCl, KCl and NaF is 4.5:4.5:1;

3) Send the secondary aluminum ash in step 1) into the preheating furnace, preheat in the preheating furnace, preheat the secondary aluminum ash to 450°C, and preheat for 60 minutes;

4) Add the molten salt in step 2) into the reaction furnace to melt the molten salt;

5) Transfer the preheated aluminum ash to the high-temperature reaction furnace, and lock the reaction furnace cover;

6) Vacuumize the reaction furnace until the pressure in the reaction furnace reaches 70Pa, and when the temperature reaches 850°C, feed AlCl ₃ gas; AlCl ₃ reacts violently with Al to form AlCl;

7) Volatile AlCl enters the cryogenic chamber at a temperature of 300°C; AlCl decomposes into AlCl ₃ and Al in the cryogenic chamber.

The present invention may be embodied in other specific forms without departing from the spirit or main characteristics of the invention. Therefore, no matter from which point of view, the above-mentioned embodiments of the present invention can only be considered as explanations of the present invention and can not limit the invention. The claims indicate the scope of the present invention, but the above description does not indicate the scope of the present invention. Therefore, any changes within the meaning and scope equivalent to the claims of the present invention should be considered to be included in the scope of the claims.

Claims (4)

1. a kind of method that aluminium is extracted in ash from aluminium, it is characterised in that comprise the following steps：

1）Prepare raw material, be through Quadratic aluminum dusts more than 60 mesh after hot stir-fry ash and cold conditions ball milling, screening；

2）Preparation fused salt, the mixture of NaCl, KCl and NaF, the mass ratio of NaCl, KCl and NaF is 4 ~ 4.5：4~4.5：1~2；

3）By step 1）In Quadratic aluminum dust feeding preheating furnace, preheated in preheating furnace, Quadratic aluminum dust is preheating to 300~ 500℃；

4）By step 2）In fused salt be added to reacting furnace in melt fused salt；

5）Aluminium ash after preheating is transferred to reacting furnace, locking reaction bell；

6）Vacuumized in reacting furnace, when furnace pressure up to 10~70Pa, and temperature is reacted up to 700~1200 DEG C, be passed through AlCl₃Gas；AlCl₃Intense reaction is played with Al, AlCl is generated；

7）Volatile matter AlCl enters low temperature chamber, and temperature is 400-500 DEG C；AlCl resolves into AlCl in low temperature chamber₃And Al.

2. the method that aluminium is extracted in a kind of ash from aluminium according to claim 1, it is characterised in that methods described is applied to two The recovery of metallic aluminium in secondary aluminium ash；The Quadratic aluminum dust is that the aluminium ash of generation in aluminum i ndustry production is extracted through conventional aluminum recovery process The residual Al ash produced after metallic aluminium.

3. the method that aluminium is extracted in a kind of ash from aluminium according to claim 1, it is characterised in that step 1）Middle preheating is secondary The time of aluminium ash is 30min ~ 120min.

4. the method that aluminium is extracted in a kind of ash from aluminium according to claim 1, it is characterised in that step 5）Decomposite AlCl₃Gas circulation is used.