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Method for recovering carbon from aluminum electrolysis waste cathodes

A technology of aluminum electrolysis waste cathodes and particles, which is applied in the field of comprehensive utilization of industrial solid waste resources, can solve problems such as equipment corrosion, environmental protection pressure, and high processing costs, and achieve high-efficiency recovery and improved impurity removal effects

Active Publication Date: 2019-11-05
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0012] There are many recycling processes for carbon in waste cathodes of aluminum electrolysis, and most of them have not been applied industrially. High environmental protection pressure, high energy consumption, etc., resulting in the lack of industrial application of its technology

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] Take 10g of waste cathode carbon blocks from an aluminum electrolytic cell in a domestic factory, the main element content is (wt%): C 70.9, Al8.23, O 9.55, F 5.38, Na 2.57, Fe 1.21, crushed to -200 mesh, accounting for 90%, Mix evenly with NaOH at a mass ratio of 1:1.7, add 20g of deionized water and 1ml of alcohol in turn, and let it stand for 4h.

[0043]After static impregnation, the waste cathode slurry was evaporated to dryness and dehydrated, and the mixed material was placed in a corundum crucible, and alkali-fused in a nitrogen atmosphere at 550°C for 2 hours in a muffle furnace; the cooled alkali-fused slag was washed with ultrasonic power 900W to the solution Neutral, washing residue filtered and dried.

[0044] Ultrasonic assisted acid leaching to remove impurities in alkaline immersion washing residue in hydrochloric acid + sodium fluoride solution, acid leaching ultrasonic power 900W, temperature 70°C, time 2h, liquid-solid ratio 10:1, H + Concentration o...

Embodiment 2

[0046] Take 30g of waste cathode carbon blocks from an aluminum electrolytic cell in a domestic factory, the main element content is (wt%): C 70.9, Al8.23, O 9.55, F 5.38, Na 2.57, Fe 1.21, crushed to -200 mesh, accounting for 90%, Mix evenly with NaOH at a mass ratio of 1:2, add 90g of deionized water and 1.5ml of alcohol in turn, and let it stand for 24 hours.

[0047] After static impregnation, the waste cathode slurry was evaporated to dryness and dehydrated, and the mixed material was placed in a corundum crucible, and alkali-fused in a nitrogen atmosphere at 320°C for 4 hours in a muffle furnace; the cooled alkali-fused slag was washed with ultrasonic power 900W until the solution showed Neutral, washing residue filtered and dried.

[0048] Ultrasonic assisted acid leaching to remove impurities in alkaline immersion water washing residue in hydrochloric acid + sodium fluoride solution, acid leaching ultrasonic power 1500W, temperature 20°C, time 8h, liquid-solid ratio 10...

Embodiment 3

[0050] Take 100g of waste cathode carbon blocks from an aluminum electrolytic cell in a domestic factory, the main element content is (wt%): C 70.9, Al8.23, O 9.55, F 5.38, Na 2.57, Fe 1.21, crushed to -200 mesh, accounting for 90%, Mix evenly with NaOH at a mass ratio of 1:3, add 600g of deionized water and 10ml of alcohol in turn, and let stand for 1h.

[0051] After static impregnation, the waste cathode slurry was evaporated to dryness and dehydrated, and the mixed material was placed in a corundum crucible, and alkali fusion was kept at 700°C for 0.5h in a helium atmosphere in a muffle furnace; the cooled alkali slag was washed with ultrasonic power 100W to The solution was neutral, and the washing residue was filtered and dried.

[0052] Ultrasonic assisted acid leaching to remove impurities in alkaline immersion washing residue in hydrochloric acid + sodium fluoride solution, acid leaching ultrasonic power 900W, temperature 70°C, time 1h, liquid-solid ratio 30:1, H + C...

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PUM

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Abstract

The invention discloses a method for recovering carbon from aluminum electrolysis waste cathodes, and the method comprises the following steps: step 1, crushing waste cathode carbon blocks of an aluminum electrolysis cell to obtain spare particles; (2) uniformly mixing the spare particles obtained in the step (1) with a solid alkali, adding deionized water, standing, and evaporating to remove moisture to obtain a mixture; step 3, heating the mixture obtained in the step 2 to 320-700 DEG C in a protective atmosphere, keeping the temperature for 0.5-4h, cooling, washing with water to neutrality,filtering and drying to obtain alkali slag; and step 4, adding the alkali slag obtained in the step 3 into a mixed solution of an acid and sodium fluoride for leaching, filtering after the leaching,and washing with water to neutrality to obtain carbon powder. The method realizes high-efficiency recovery of carbon components in the waste cathode carbon blocks, and the purity of the obtained carbon powder is not less than 99.0%.

Description

technical field [0001] The invention relates to a method for recovering carbon from waste cathodes of aluminum electrolysis, and belongs to the technical field of comprehensive utilization of industrial solid waste resources. [0002] technical background [0003] Aluminum is currently the non-ferrous metal with the largest output and application. Hall-Heroult molten salt electrolysis is the main process of aluminum smelting. Aluminum electrolytic cells generally need to be overhauled after 3-10 years of operation, and a large number of spent cathode carbon blocks are discharged outside the overhaul. Data show that for every 1t of electrolytic aluminum produced, about 10kg of waste cathode materials will be produced. Based on this estimate, my country produced 360,000 tons of waste cathode materials for aluminum electrolysis in 2017 alone. [0004] In the waste cathode of aluminum electrolysis, carbon accounts for 50% to 80%, and the rest is electrolyte, mainly cryolite, s...

Claims

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Application Information

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IPC IPC(8): C01B32/05
CPCC01B32/05
Inventor 肖劲王志安仲奇凡唐雷
Owner CENT SOUTH UNIV
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