阅读说明：本技术 一种二次铝灰回收方法 (Secondary aluminum ash recovery method ) 是由 白培康 尚云骢 张文达 赵占勇 赵戎 于 2021-02-01 设计创作，主要内容包括：本发明提出一种二次铝灰回收方法,属于铝灰回收技术领域；具体是在二次铝灰中加入熔盐,二者充分混合浸湿得到混合物；将混合物置于连续挤压输出装置,通过挤压将混合物挤出至冷却装置中凝固；将凝固后的固体经破碎和筛分,分离出金属铝和残余物；本发明通过熔盐和物理挤压的方式相结合使二次铝灰中细小量少的铝粒汇集并以固态输出,操作简单、易于控制、二次铝灰中的金属铝回收率高。(The invention provides a secondary aluminum ash recovery method, belonging to the technical field of aluminum ash recovery; adding molten salt into the secondary aluminum ash, and fully mixing and soaking the molten salt and the secondary aluminum ash to obtain a mixture; placing the mixture in a continuous extrusion output device, extruding the mixture into a cooling device by extrusion and solidifying; crushing and screening the solidified solid to separate out metal aluminum and residues; the method combines the molten salt and physical extrusion to collect small and small aluminum particles in the secondary aluminum ash and output the aluminum particles in a solid state, and has the advantages of simple operation, easy control and high recovery rate of metal aluminum in the secondary aluminum ash.)

1. The method for recovering the secondary aluminum ash is characterized by comprising the following steps of:

a) adding molten salt into the secondary aluminum ash; the mass ratio of the secondary aluminum ash to the molten salt is 5: 1-8: 1; enabling the temperature of the mixture of the secondary aluminum ash and the molten salt to be more than or equal to 680 ℃, and preserving the heat for 20-40 min to fully mix and soak the secondary aluminum ash and the molten salt;

b) placing a mixture obtained by fully mixing and soaking secondary aluminum ash and molten salt in a continuous extrusion output device, and extruding the mixture into a cooling device for solidification through extrusion;

c) and crushing and screening the solidified solid to separate out the metallic aluminum and residues.

2. The secondary aluminum ash recovery method of claim 1, wherein the molten salt is NaC1, KCI and Na₃AlF₆Mixture of (1), NaC1, KCI and Na₃AlF₆The mass ratio of the components is 4-4.5: 1-2 respectively.

3. The secondary aluminum ash recovery method of claim 1, wherein the residue is subjected to hydrolysis leaching, evaporation and crystallization to obtain molten salt.

4. The method for recycling secondary aluminum ash as claimed in claim 1, wherein the continuous extrusion output device adopts screw extrusion, and the screw rotation speed is 240-360 r/min.

5. The secondary aluminum ash recovery method of claim 1 or 4 wherein the temperature in the continuous extrusion output device is maintained at > 680 ℃.

Technical Field

The invention belongs to the technical field of aluminum ash recovery treatment, and relates to a secondary aluminum ash recovery method.

Background

Aluminum ash is a slag produced during the industrial production of aluminum and contains aluminum and various other elements. The aluminum ash is divided into primary aluminum ash and secondary aluminum ash, and the secondary aluminum ash is fine ash obtained by further screening the primary aluminum ash after being treated by a recycling process such as ash frying and the like. The recycling rate of the primary aluminum ash is higher in the current enterprises, and the recycling energy brings higher economic benefits due to the higher aluminum content in the primary aluminum ash. The recycling rate of the secondary aluminum ash is relatively low, and the secondary aluminum ash has lower aluminum content and high treatment difficulty compared with the primary aluminum ash. At present, the recycling of the secondary aluminum ash is mostly concentrated on the production of products such as baking-free bricks, refractory materials and the like.

CN111167830A comprehensive treatment and utilization process of secondary aluminum ash, the treatment method of the secondary aluminum ash is to obtain filter residue by three procedures of deamination, fluorine fixation and centrifugal dehydration, and the filter residue is used for producing baking-free bricks. CN111170750A method for making refractory material by innocent treatment of secondary aluminum ash, the method for treating secondary aluminum ash comprises screening secondary aluminum ash with a screen, oxidizing in 12% -18% oxygen atmosphere, calcining at 1150-1550 ℃ for 0.5-4 h, mixing the calcined oxide with an additive, and finally arc melting to obtain the refractory material.

The two methods for recovering the secondary aluminum ash are used for producing baking-free bricks and refractory materials, and as a part of larger aluminum particles in the aluminum ash obtained by hot-frying the aluminum slag are recovered by ball milling and screening, but some small aluminum particles cannot be further recovered (the aluminum content is 5-8%) under the conventional hot-frying ash process, great waste is caused, and the extraction and recovery of the aluminum in the secondary aluminum ash are rarely involved. Therefore, the development of a simple and efficient secondary aluminum ash recovery method has important practical significance.

Disclosure of Invention

The invention overcomes the defects of the prior art, provides a secondary aluminum ash recovery method, and aims to recover the secondary aluminum ash containing aluminum particles with small particle size and low content and improve the recovery and utilization value of aluminum in the secondary aluminum ash.

In order to achieve the above object, the present invention is achieved by the following technical solutions.

A secondary aluminum ash recovery method comprises the following steps:

a) adding molten salt into the secondary aluminum ash; the mass ratio of the secondary aluminum ash to the molten salt is 5: 1-8: 1; and (3) keeping the temperature of the mixture of the secondary aluminum ash and the molten salt to be more than or equal to 680 ℃ and preserving the heat for 20-40 min, so that the secondary aluminum ash and the molten salt are fully mixed and soaked.

b) And (3) placing the mixture obtained by fully mixing and soaking the secondary aluminum ash and the molten salt in a continuous extrusion output device, and extruding the mixture into a cooling device through extrusion to solidify.

c) And crushing and screening the solidified solid to separate out the metallic aluminum and residues.

Preferably, the molten salt is NaC1, KCI and Na₃AlF₆Mixture of (1), NaC1, KCI and Na₃AlF₆The mass ratio of the components is 4-4.5: 1-2 respectively.

Preferably, the residue is subjected to hydrolysis leaching, evaporation and crystallization to obtain molten salt.

Preferably, the continuous extrusion output device adopts spiral extrusion, and the rotating speed of a screw is 240-360 r/min.

Preferably, the temperature in the continuous extrusion output device is maintained at > 680 ℃.

Compared with the prior art, the invention has the beneficial effects that.

The method has the advantages of simple operation, easy control and high recovery rate of the metal aluminum in the secondary aluminum ash. The principle of the invention is that simple substance aluminum wrapped by oxides such as aluminum oxide is melted out through molten salt at high temperature, then molten aluminum in a mixture of the molten salt and aluminum ash flows and gathers through a rotary extrusion device, and the molten aluminum can be screened and separated out after cooling, and then the separated ash and the molten salt are subjected to subsequent hydrolysis, leaching, evaporation and crystallization to separate and recover the oxides and the molten salt.

The melted simple substance aluminum is extruded to form large-particle aluminum particles, and the simple substance aluminum which is difficult to extract and separate in the past can be quickly separated from impurities through simple screening operation; the molten salt used in the method can be reused after hydrolysis, evaporation and crystallization, and the residual oxide can be used for producing refractory materials, so that the secondary aluminum ash amount can be greatly reduced, and no new harmful substances are generated, thereby reducing the harm to the environment and improving the economic benefit of enterprises.

Drawings

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the following drawings are taken for illustration:

FIG. 1 is a schematic structural diagram of a secondary aluminum ash recovery device.

FIG. 2 is a graph of the macro-morphology of the aluminum particles obtained in examples 1-3.

Figure 3 is an XRD pattern after molten salt leaching.

FIG. 4 is a graph comparing the morphology of an un-extruded secondary aluminum ash mixture with the morphology of the aluminum particles aggregated in the extruded aluminum ash of the present invention.

In fig. 1: 1-motor, 2-screw, 3-feed inlet, 4-furnace lining layer, 5-resistance wire layer, 6-heat insulation layer, 7-steel shell, 8-cooling crushing roller, 9-screening roller, 10-hydrolysis leaching device and 11-evaporation crystallizing device.

A, B, C in FIG. 2 are the macro-topography maps of the aluminum particles obtained in examples 1, 2 and 3, respectively;

in fig. 4, D is the mixture of the secondary aluminum ash fried ash without the rotary extrusion processed by only adding the molten salt, and E is the mixture of the secondary aluminum ash fried ash without the rotary extrusion processed by adding the molten salt in the invention.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail with reference to the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The technical solution of the present invention is described in detail below with reference to the embodiments and the drawings, but the scope of protection is not limited thereto.

Example 1

1) Aluminum slag produced from smelting furnace is fried by rotary kiln to recover aluminumAfter the liquid is obtained, adding a certain amount of molten salt into the residual secondary aluminum ash, and fully mixing; the molten salt is NaC1, KCI and Na₃AlF₆Mixture of (1), NaC1, KCI and Na₃AlF₆The mass ratio of (A) to (B) is 4.5: 4: 1; the mass ratio of the secondary aluminum ash to the molten salt is 5:1, and the mixture of the secondary aluminum ash and the molten salt is kept at 750 ℃ for 20min to be fully mixed and soaked.

2) The mixture is extruded by a continuous extrusion device, as shown in figure 1, the continuous extrusion device is provided with an extrusion cavity, a screw rod 2 is arranged in the extrusion cavity, the top of the extrusion cavity is provided with a feed inlet 3, the wall of the extrusion cavity sequentially comprises a furnace lining layer 4, a resistance wire layer 5, a heat insulation layer 6 and an outermost steel shell 7 from inside to outside, and the outlet of the extrusion cavity is sequentially connected with a cooling crushing roller 8, a screening roller 9, a hydrolysis leaching device 10 and an evaporation crystallization device 11; the temperature in the continuous extrusion device is kept above 680 ℃, and the mixture of the secondary aluminum ash and the molten salt enters the continuous extrusion device through the feed inlet 3. The screw 2 extrudes the mixture of the secondary aluminum ash and the molten salt, the rotating speed of the screw 2 is 360r/min, and fine aluminum particles in the mixture flow out and are gathered under the action of the molten salt and the extrusion force.

3) The extrudate enters a cooling crushing roller 8 through an extrusion opening to be cooled and crushed; and (3) feeding the crushed mixture into a screening roller 9, and screening out the metal aluminum and residues to obtain the target product metal aluminum.

4) The residue is further passed through a hydrolysis leaching device 10 and an evaporation crystallizing device 11, and is hydrolyzed, leached, evaporated and crystallized to obtain salt, the recovered salt can be reused, and the residual oxide can be used for producing refractory materials.

Example 2

1) After aluminum slag produced from a smelting furnace is fried by a rotary kiln to recover aluminum liquid, adding a certain amount of molten salt into the residual secondary aluminum ash, and fully mixing; the molten salt is NaC1, KCI and Na₃AlF₆Mixture of (1), NaC1, KCI and Na₃AlF₆The mass ratio of (A) to (B) is respectively 4: 4.5: 1.5; the mass ratio of the secondary aluminum ash to the molten salt is 7:1, and the mixture of the secondary aluminum ash and the molten salt is kept at 700 ℃ for 30min to be fully mixed and soaked.

2) The mixture is extruded by a continuous extrusion device, as shown in figure 1, the continuous extrusion device is provided with an extrusion cavity, a screw rod 2 is arranged in the extrusion cavity, the top of the extrusion cavity is provided with a feed inlet 3, the wall of the extrusion cavity sequentially comprises a furnace lining layer 4, a resistance wire layer 5, a heat insulation layer 6 and an outermost steel shell 7 from inside to outside, and the outlet of the extrusion cavity is sequentially connected with a cooling crushing roller 8, a screening roller 9, a hydrolysis leaching device 10 and an evaporation crystallization device 11; the temperature in the continuous extrusion device is kept above 680 ℃, and the mixture of the secondary aluminum ash and the molten salt enters the continuous extrusion device through the feed inlet 3. The screw 2 extrudes the mixture of the secondary aluminum ash and the molten salt, the rotating speed of the screw 2 is 300r/min, and fine aluminum particles in the mixture flow out and are gathered under the action of the molten salt and the extrusion force.

3) The extrudate enters a cooling crushing roller 8 through an extrusion opening to be cooled and crushed; and (3) feeding the crushed mixture into a screening roller 9, and screening out the metal aluminum and residues to obtain the target product metal aluminum.

4) The residue is further passed through a hydrolysis leaching device 10 and an evaporation crystallizing device 11, and is hydrolyzed, leached, evaporated and crystallized to obtain salt, the recovered salt can be reused, and the residual oxide can be used for producing refractory materials.

Example 3

1) After aluminum slag produced from a smelting furnace is fried by a rotary kiln to recover aluminum liquid, adding a certain amount of molten salt into the residual secondary aluminum ash, and fully mixing; the molten salt is NaC1, KCI and Na₃AlF₆Mixture of (1), NaC1, KCI and Na₃AlF₆The mass ratio of (A) to (B) is 4.2: 4.2: 2; the mass ratio of the secondary aluminum ash to the molten salt is 8:1, and the mixture of the secondary aluminum ash and the molten salt is kept at 780 ℃ for 40min to be fully mixed and soaked.

2) The mixture is extruded by a continuous extrusion device, as shown in figure 1, the continuous extrusion device is provided with an extrusion cavity, a screw rod 2 is arranged in the extrusion cavity, the top of the extrusion cavity is provided with a feed inlet 3, the wall of the extrusion cavity sequentially comprises a furnace lining layer 4, a resistance wire layer 5, a heat insulation layer 6 and an outermost steel shell 7 from inside to outside, and the outlet of the extrusion cavity is sequentially connected with a cooling crushing roller 8, a screening roller 9, a hydrolysis leaching device 10 and an evaporation crystallization device 11; the temperature in the continuous extrusion device is kept above 680 ℃, and the mixture of the secondary aluminum ash and the molten salt enters the continuous extrusion device through the feed inlet 3. And extruding the mixture of the secondary aluminum ash and the molten salt by the screw 2, wherein the rotating speed of the screw 2 is 240r/min, and fine aluminum particles in the mixture flow out and are gathered under the action of the molten salt and the extrusion force.

3) The extrudate enters a cooling crushing roller 8 through an extrusion opening to be cooled and crushed; and (3) feeding the crushed mixture into a screening roller 9, and screening out the metal aluminum and residues to obtain the target product metal aluminum.

4) The residue is further passed through a hydrolysis leaching device 10 and an evaporation crystallizing device 11, and is hydrolyzed, leached, evaporated and crystallized to obtain salt, the recovered salt can be reused, and the residual oxide can be used for producing refractory materials.

In fig. 2, A, B, C are respectively macro-morphology graphs of aluminum particles recovered by different processes in examples 1 to 3, and it can be seen from the graphs that, the aluminum recovered in example 1 is more than that recovered in example 2, and the aluminum recovered in example 2 is more than that recovered in example 3, which indicates that the higher the salt ratio is, the higher the recovery rate of aluminum in aluminum ash is, and when the salt amount is increased, the aluminum ash tends to be completely wetted, and the recovery rate of aluminum is increased. Fig. 3 is an XRD chart after the molten salt leaching, from which it can be seen that the solid substances remaining after the evaporation of the leached aqueous solution are NaCl and KCl, and thus can be continuously used for a second time. FIG. 4 shows (D) a secondary aluminum ash mixture treated with only molten salt without rotary extrusion and (E) a secondary aluminum ash mixture treated with molten salt and with rotary extrusion, respectively. Obviously, the method can better aggregate and grow the simple substance aluminum in the secondary aluminum ash, thereby being capable of efficiently screening and separating; the rotary extrusion method adopted by the invention is not adopted, and only molten salt is adopted, so that the simple substance aluminum in the secondary aluminum ash can be exposed, but the simple substance aluminum cannot be aggregated and grown, and cannot be effectively separated from the aluminum ash.

While the invention has been described in further detail with reference to specific preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.