A kind of resource treatment method of aluminum ash

Abstract

The present invention relates to the technical field of resource processing of aluminum ash, and specifically to a resource processing method of aluminum ash. The resource processing method of aluminum ash provided by the present invention comprises the following steps: mixing aluminum ash, anode carbon slag and waste cathode carbon block and then mechanically activating to obtain a mixed material; placing the mixed material in a conductive device, and passing carbon dioxide gas and water vapor into the conductive device, then connecting a DC power supply to the conductive device, passing a 40A-50A DC current to make the mixed material reach 650-850°C, stopping the introduction of carbon dioxide gas and water vapor after the power is turned on, cooling, taking out the material, grinding, and then placing the ground material in an alkaline solution for leaching to obtain a sodium aluminate solution and solid slag. The resource processing method of aluminum ash provided by the present invention can effectively improve the aluminum oxide dissolution rate of clinker and reduce the nitrogen content in the solid slag.

Description

Technical Field

[0001] The invention relates to the technical field of resource processing of aluminum ash, and in particular to a resource processing method of aluminum ash. Background Art

[0002] Aluminum ash is a hazardous solid waste generated during the smelting and casting of primary aluminum, processing of aluminum products, and recycling. The aluminum nitride in aluminum ash is highly reactive. When stored in the open air, it reacts with moist air, releasing toxic and pungent ammonia, causing air pollution that harms human health. The harmful substances, soluble fluorides and chlorides, are easily dissolved into the soil, polluting groundwater and rivers. The above pollutants are complex and difficult to remove in depth, which limits the safe disposal and resource utilization of aluminum ash.

[0003] In the prior art, there are two methods for extracting aluminum from aluminum ash: acid method and alkaline method, which are carried out by acid dissolution or alkaline roasting. However, since aluminum ash contains a large amount of α-Al2O3 that is difficult to dissolve in acid and alkali, both methods have the problem of low aluminum oxide extraction rate and high nitrogen content in solid slag. Summary of the invention

[0004] In order to overcome the problems of low alumina extraction rate and high nitrogen content in solid slag in the existing method of extracting aluminum from aluminum ash, a resource processing method for aluminum ash is provided.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] A method for recycling aluminum ash comprises the following steps:

[0007] 1) mixing aluminum ash, anode carbon slag and waste cathode carbon block and then mechanically activating them to obtain a mixed material;

[0008] 2) placing the mixed material in a conductive device, and introducing carbon dioxide gas and water vapor into the conductive device, then connecting a DC power supply to the conductive device, and introducing a 40A-50A DC current to make the mixed material reach 650-850° C. After the power is turned on, stop introducing carbon dioxide gas and water vapor, cool down, take out the material, grind it, and then place the ground material in an alkaline solution for leaching to obtain a sodium aluminate solution and solid slag.

[0009] The anode carbon slag and waste cathode carbon block in the present invention are both anode carbon slag and waste cathode carbon block of aluminum electrolytic cell. The Al2O3 content in aluminum ash is 50-60%, and the Al content is 7-12%; the C content in the anode carbon slag is 40-50%, the NaF content is 10-18%, and the Na3AlF6 content is 3-7%; the C content in the waste cathode carbon block is 50-55%, the NaF content is 10-20%, and the Na3AlF6 content is 4-8%.

[0010] Preferably, the mass ratio of the aluminum ash, anode carbon slag and waste cathode carbon block is 1:(0.7-0.8):(0.2-0.4).

[0011] Preferably, the introduction rate of carbon dioxide is 20-40 ml / min, and the introduction rate of water vapor is 20-40 ml / min.

[0012] Preferably, in step 2), a 40A-50A direct current is introduced to make the mixed material reach 650-850° C. and maintain it for 20-40 seconds.

[0013] Preferably, the conductive device is a graphite crucible.

[0014] Preferably, the alkaline solution is a sodium hydroxide solution.

[0015] Preferably, the concentration of the sodium hydroxide solution is 20-200 g / L.

[0016] Preferably, the mechanical activation is performed by grinding, and the grinding time is 1-6 hours.

[0017] Preferably, the liquid-to-solid ratio in the leaching step is 1:(0.3-1).

[0018] Preferably, the leaching temperature is 50-150° C., and the leaching time is 0.5-2 h.

[0019] Beneficial effects of the present invention:

[0020] The resource processing method of aluminum ash provided by the present invention first mechanically activates the aluminum ash, anode carbon slag and waste cathode carbon block by mixing, and then rapidly heats and roasts the mixed material by direct current. Under the action of strong current, the aluminum-containing components in the mixed material are rapidly fluorinated and dissociated. At the same time, during the fluorination dissociation process, the fluoride in the anode carbon slag and the waste cathode carbon block plays a role in destroying the insoluble phase α-Al2O3 structure in the aluminum ash, converting it into an alkali-soluble state; the carbonaceous material plays a role in providing heat and reducing atmosphere, avoiding secondary oxidation of the aluminum component in the high-temperature process, and the harmful substance aluminum nitride in the aluminum ash is decomposed into harmless nitrogen at high temperature, thereby realizing the recycling of aluminum ash. Detoxification treatment; at the same time, carbon dioxide gas and water vapor are continuously introduced during the temperature rising roasting process. The carbon dioxide gas and water vapor quickly penetrate into the mixed material during the fluorination dissociation process, further assist the rapid fluorination dissociation of the aluminum-containing component, and destroy the insoluble components in the mixed material. After the temperature rising roasting is completed, alkali dissolution is carried out to obtain sodium aluminate solution and solid slag. The sodium aluminate solution can be used to obtain alumina through subsequent roasting and other processes. After testing, the method provided by the present invention can effectively improve the alumina dissolution rate of the clinker and reduce the nitrogen content in the solid slag. At the same time, it also safely utilizes and disposes of two types of hazardous wastes, anode carbon slag and waste cathode carbon blocks, and well realizes the resource utilization of waste. DETAILED DESCRIPTION

[0021] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0022] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0023] The aluminum ash used in the following embodiments and comparative examples has an Al2O3 content of 54.5% and an Al content of 8.7%; the anode carbon slag and the waste cathode carbon blocks are both anode carbon slag and waste cathode carbon blocks of aluminum electrolytic cells, wherein the C content of the anode carbon slag is 49.3%, the NaF content is 14.5%, and the Na3AlF6 content is 4.2%; the C content of the waste cathode carbon blocks is 54.3%, the NaF content is 18.5%, and the Na3AlF6 content is 5.7%.

[0024] Example 1

[0025] This embodiment provides a method for recycling aluminum ash, comprising the following steps:

[0026] 1) Weigh 100 g, 80 g, and 20 g of aluminum ash, anode carbon slag, and waste cathode carbon block, respectively, mix them, grind and activate them for 3 hours, and obtain a mixed material;

[0027] 2) The mixed material is placed in a closed graphite crucible, and carbon dioxide gas and water vapor are continuously introduced, the introduction rate of carbon dioxide is 20 ml / min, and the introduction rate of water vapor is 20 ml / min, then a DC power supply is connected to both ends of the graphite crucible, and a 50A DC current is introduced to quickly make the material in the graphite crucible reach 850° C. and maintain it for 30 seconds. After the power is turned on, the introduction of carbon dioxide gas and water vapor is stopped, and the graphite crucible is cooled to room temperature, the clinker is taken out, ground, and then the ground clinker is placed in a sodium hydroxide solution with a concentration of 120 g / L for leaching, the leaching temperature is 135° C., the liquid-to-solid ratio is 1:0.3, and the leaching time is 1 hour to obtain a sodium aluminate solution and solid slag. After analysis, the aluminum oxide dissolution rate of the clinker is 96.2%, and the nitrogen content in the solid slag is less than 0.05%.

[0028] Example 2

[0029] This embodiment provides a method for recycling aluminum ash, comprising the following steps:

[0030] 1) Weigh 100 g, 80 g, and 30 g of aluminum ash, anode carbon slag, and waste cathode carbon block, respectively, mix them, grind and activate them for 4 hours, and obtain a mixed material;

[0031] 2) The mixed material is placed in a closed graphite crucible, and carbon dioxide gas and water vapor are continuously introduced, the introduction rate of carbon dioxide is 20 ml / min, and the introduction rate of water vapor is 20 ml / min, then a DC power supply is connected to both ends of the graphite crucible, a 50A DC current is introduced to quickly make the material in the graphite crucible reach 850° C., and maintained for 35 seconds. After the power-on is completed, the introduction of carbon dioxide gas and water vapor is stopped, the graphite crucible is cooled to room temperature, the clinker is taken out, ground, and then the ground clinker is placed in a sodium hydroxide solution with a concentration of 120 g / L for leaching, the leaching temperature is 145° C., the liquid-to-solid ratio is 1:0.4, and the leaching time is 1.5 hours to obtain a sodium aluminate solution and solid slag. After analysis, the aluminum oxide dissolution rate of the clinker is 97.4%, and the nitrogen content in the solid slag is <0.05%.

[0032] Example 3

[0033] This embodiment provides a method for recycling aluminum ash, comprising the following steps:

[0034] 1) Weigh 100 g, 80 g, and 40 g of aluminum ash, anode carbon slag, and waste cathode carbon block, respectively, mix them, grind and activate them for 6 hours, and obtain a mixed material;

[0035] 2) The mixed material is placed in a closed graphite crucible, and carbon dioxide gas and water vapor are continuously introduced, the introduction rate of carbon dioxide is 20 ml / min, and the introduction rate of water vapor is 20 ml / min, then a DC power supply is connected to both ends of the graphite crucible, a 50A DC current is introduced to quickly make the material in the graphite crucible reach 850° C., and maintained for 35 seconds. After the power-on is completed, the introduction of carbon dioxide gas and water vapor is stopped, the graphite crucible is cooled to room temperature, the clinker is taken out, ground, and then the ground clinker is placed in a sodium hydroxide solution with a concentration of 180 g / L for leaching, the leaching temperature is 150° C., the liquid-to-solid ratio is 1:0.5, and the leaching time is 2.0 hours to obtain a sodium aluminate solution and solid slag. After analysis, the aluminum oxide dissolution rate of the clinker is 97.9%, and the nitrogen content in the solid slag is <0.05%.

[0036] Comparative Example 1

[0037] The present comparative example provides a resource treatment method for aluminum ash, which differs from Example 1 in that in step 2), the mixed material is placed in a closed graphite crucible, and then a DC power supply is connected to both ends of the graphite crucible, a 50A DC current is passed to make the material in the graphite crucible quickly reach 850°C and maintained for 30s, after the power is turned on, the graphite crucible is cooled to room temperature, the clinker is taken out, ground, and then the ground clinker is placed in a sodium hydroxide solution with a concentration of 120g / L for leaching, the leaching temperature is 135°C, the liquid-to-solid ratio is 1:0.3, the leaching time is 1h, and a sodium aluminate solution and solid slag are obtained. After analysis, the aluminum oxide dissolution rate of the clinker is 85.4%, and the nitrogen content in the solid slag is <0.2%.

[0038] Comparative Example 2

[0039] The present comparative example provides a resource treatment method for aluminum ash, which is different from Example 1 in that in step 2), the mixed material is placed in a closed graphite crucible and water vapor is continuously introduced at a rate of 40 ml / min, and then a DC power supply is connected to both ends of the graphite crucible, and a 50A DC current is introduced to make the material in the graphite crucible quickly reach 850°C and maintain it for 30 seconds. After the power is turned on, the introduction of water vapor is stopped, the graphite crucible is cooled to room temperature, the clinker is taken out and ground, and then the ground clinker is placed in a sodium hydroxide solution with a concentration of 120 g / L for leaching, the leaching temperature is 135°C, the liquid-to-solid ratio is 1:0.3, and the leaching time is 1 hour to obtain a sodium aluminate solution and solid slag. After analysis, the aluminum oxide dissolution rate of the clinker is 87.1%, and the nitrogen content in the solid slag is <0.2%.

[0040] Comparative Example 3

[0041] The present comparative example provides a resource treatment method for aluminum ash, which differs from Example 1 in that in step 2), the mixed material is placed in a closed heating furnace, and carbon dioxide gas and water vapor are continuously introduced, the introduction rate of carbon dioxide is 20 ml / min, and the introduction rate of water vapor is 20 ml / min, and then the heating furnace is heated by a laboratory electric furnace to make the material in the heating furnace reach 850°C and maintain it for 30 seconds. After the heating is completed, the introduction of carbon dioxide gas and water vapor is stopped, the heating furnace is cooled to room temperature, the clinker is taken out and ground, and then the ground clinker is placed in a sodium hydroxide solution with a concentration of 120 g / L for leaching, the leaching temperature is 135°C, the liquid-to-solid ratio is 1:0.3, and the leaching time is 1 hour to obtain a sodium aluminate solution and solid slag. After analysis, the aluminum oxide dissolution rate of the clinker is 61.6%, and the nitrogen content in the solid slag is <3.0%.

[0042] Comparative Example 4

[0043] The present comparative example provides a resource treatment method for aluminum ash, which differs from Example 1 in that in step 2), the mixed material is placed in a closed heating furnace, and carbon dioxide gas and water vapor are continuously introduced, the introduction rate of carbon dioxide is 20 ml / min, and the introduction rate of water vapor is 20 ml / min, and then the heating furnace is heated by a laboratory electric furnace to make the material in the heating furnace reach 850°C and maintained for 120 minutes. After the heating is completed, the introduction of carbon dioxide gas and water vapor is stopped, the heating furnace is cooled to room temperature, the clinker is taken out and ground, and then the ground clinker is placed in a sodium hydroxide solution with a concentration of 120 g / L for leaching, the leaching temperature is 135°C, the liquid-to-solid ratio is 1:0.3, and the leaching time is 1 hour to obtain a sodium aluminate solution and solid slag. After analysis, the aluminum oxide dissolution rate of the clinker is 88.9%, and the nitrogen content in the solid slag is <0.1%.

[0044] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A resource processing method for aluminum ash, It is characterized in that The steps include: 1) Aluminum ash, anode carbon slag and waste cathode carbon blocks are mixed and mechanically activated to obtain a mixed material; 2) placing the mixed material in a conductive device, and introducing carbon dioxide gas and water vapor into the conductive device, then connecting a DC power supply to the conductive device, introducing a 40A-50A DC current to make the mixed material reach 650-850°C, stopping the introduction of carbon dioxide gas and water vapor after the power supply is turned off, cooling the material, taking out the material, grinding it, and then placing the ground material in an alkaline solution for leaching to obtain a sodium aluminate solution and solid slag; The mass ratio of the aluminum ash, anode carbon slag and waste cathode carbon block is 1: (0.7-0.8): (0.2-0.4); The carbon dioxide is introduced at a rate of 20-40 ml / min, and the water vapor is introduced at a rate of 20-40 ml / min; In step 2), a 40A-50A direct current is passed to make the mixed material reach 650-850°C and maintained for 20-40 seconds; The conductive device is a graphite crucible.

2. The resource processing method of aluminum ash according to claim 1, It is characterized in that The alkaline solution is a sodium hydroxide solution.

3. The resource processing method of aluminum ash according to claim 2, It is characterized in that The concentration of the sodium hydroxide solution is 20-200 g / L.

4. The resource recovery method of aluminum ash according to claim 1, It is characterized in that The mechanical activation is carried out by grinding, and the grinding time is 1-6h.

5. The resource processing method of aluminum ash according to claim 1, It is characterized in that The liquid-to-solid ratio in the leaching step is 1:(0.3-1).

6. The resource processing method of aluminum ash according to claim 5, It is characterized in that The leaching temperature is 50-150° C., and the leaching time is 0.5-2 h.