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A method for deep removal of fluorine by microwave roasting-hydrothermal alkali immersion of waste cathode of aluminum electrolysis

A technology of aluminum electrolysis waste cathode and microwave roasting, which is applied to the preparation/purification of aluminum fluoride, aluminum halide, carbon, etc., can solve the problems of slow heating rate, long holding time, and incomplete treatment of high temperature treatment, and achieve the holding time The effect of reduction, strong absorbing ability, and shortened processing time

Active Publication Date: 2021-03-19
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] In order to solve the above problems, the present invention provides a method of microwave roasting-hydrothermal alkali immersion for deep fluorine removal of aluminum electrolysis spent cathodes, which utilizes the characteristics of strong microwave-absorbing ability of carbon-based materials, uses microwaves to achieve rapid temperature rise, and the holding time is extremely short. Reduction to a large extent for one-time treatment, and then advanced treatment by microwave hydrothermal treatment, which can realize the recycling of fluoride and carbon, and solve the problems of slow heating rate, long holding time and incomplete treatment of high-temperature treatment.

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  • A method for deep removal of fluorine by microwave roasting-hydrothermal alkali immersion of waste cathode of aluminum electrolysis
  • A method for deep removal of fluorine by microwave roasting-hydrothermal alkali immersion of waste cathode of aluminum electrolysis
  • A method for deep removal of fluorine by microwave roasting-hydrothermal alkali immersion of waste cathode of aluminum electrolysis

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Embodiment 1

[0030] Among the components of the waste cathode carbon block used in the present embodiment, according to weight percentage, it contains 58.4% carbon, 14.7% oxygen, 12.7% fluorine, 9.37% sodium, and 0.8% calcium, and the balance is alumina and its trace elements.

[0031] Crushing and screening: crush the waste cathode carbon blocks of aluminum electrolysis, and then sieve after crushing. If the particle size is 1-3cm, it will directly enter high-temperature microwave roasting, if it is larger than 3cm, it will be crushed again, and if it is smaller than 1cm, it will go into grinding.

[0032] High-temperature microwave heat treatment: first put the crushed carbon block into the isolation net of the quartz crucible, and then put the crucible into the high-temperature microwave equipment and pass in argon gas for high-temperature treatment. The microwave equipment uses infrared temperature measurement, and its power is 1000W. The temperature is 1100°C, and the holding time is 2...

Embodiment 2

[0037] Among the components of the waste cathode carbon block used in the present embodiment, according to weight percentage, it contains 58.4% carbon, 14.7% oxygen, 12.7% fluorine, 9.37% sodium, and 0.8% calcium, and the balance is alumina and its trace elements.

[0038] Crushing and screening: crush the waste cathode carbon blocks of aluminum electrolysis, and then sieve after crushing. If the particle size is 1-3cm, it will directly enter high-temperature microwave roasting, if it is larger than 3cm, it will be crushed again, and if it is smaller than 1cm, it will go into grinding.

[0039] High-temperature microwave heat treatment: first put the crushed carbon block on the isolation net of the quartz crucible, then put the crucible into the high-temperature microwave equipment and pass in argon gas for high-temperature treatment. The microwave equipment uses infrared temperature measurement, and its power is 1500W. The temperature is 1150°C, and the holding time is 30 minute...

Embodiment 3

[0044] Among the components of the waste cathode carbon block used in the present embodiment, according to weight percentage, it contains 58.4% carbon, 14.7% oxygen, 12.7% fluorine, 9.37% sodium, and 0.8% calcium, and the balance is alumina and its trace elements.

[0045] Crushing and screening: crush the waste cathode carbon blocks of aluminum electrolysis, and then sieve after crushing. If the particle size is 1-3cm, it will directly enter high-temperature microwave roasting, if it is larger than 3cm, it will be crushed again, and if it is smaller than 1cm, it will go into grinding.

[0046] High-temperature microwave heat treatment: First, put the crushed carbon block on the isolation net of the quartz crucible, and then put the crucible into the high-temperature microwave equipment and inject argon gas for high-temperature treatment. The microwave equipment uses infrared temperature measurement, and its power is 2500W. The temperature is 1200°C, and the holding time is 50 ...

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Abstract

The invention discloses an aluminum electrolysis waste cathode microwave roasting-hydrothermal alkaline leaching deep defluorination method, and relates to the technical field of aluminum electrolysiswaste cathode treatment. The method comprises the following specific steps of: crushing waste cathode carbon blocks, and performing screening after crushing; carrying out microwave high-temperature roasting on the obtained waste cathode carbon blocks in a protective atmosphere environment; introducing oxygen in the cooling process of the roasted waste cathode carbon block to remove cyanide, and then adopting a sample grinding machine for grinding; adding the ground carbon powder into an alkaline solution with a certain concentration, putting the mixture into a hydrothermal reaction tank, andperforming alkaline liquor leaching treatment under a microwave heating condition. One-time efficient physical separation of cryolite is realized by adopting microwave high-temperature roasting, secondary deep defluorination is achieved through microwave hydrothermal alkali liquor leaching, harmful substances like fluorides and cyanides in the aluminum electrolysis waste cathode carbon blocks areremoved, and harmless recovery of the aluminum electrolysis waste cathode carbon blocks is achieved, therefore the purposes of reducing environmental pollution and achieving cyclic utilization and appreciation are achieved.

Description

technical field [0001] The invention relates to the technical field of aluminum electrolysis waste cathode treatment, in particular to a method for deep fluorine removal of aluminum electrolysis waste cathode by microwave roasting-hydrothermal alkali immersion. Background technique [0002] my country is the world's largest producer of aluminum, and cryolite-alumina molten salt electrolysis is the main method of producing aluminum. During the electrolysis process, due to the generation of metallic sodium, it passes through the cathode of the aluminum electrolytic cell with a porous structure. The carbon block material penetrates inside and reacts with carbon. Moreover, as cryolite, alumina, sodium fluoride, calcium fluoride and other substances enter the cathode carbon block, too high impurity content in the cathode carbon block will lead to a decrease in current efficiency and cathode expansion and damage. Therefore, aluminum electrolysis cathode carbon blocks need Replace ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B32/05C01F7/54
CPCC01F7/54C01B32/05
Inventor 许磊朱知刘建华彭金辉张利波韩朝辉巨少华夏洪应任义尧田时泓
Owner KUNMING UNIV OF SCI & TECH