DESIGN STUDY: FLOTATION CONCENTRATE FROM A POTLINING TREATMENT CENTER

ISSUE

Spent potlining comes from reduction pots in the aluminum electrolysis process. Made up of carbon, refractory brick and other products, spent potlining is usually pretreated and then buried with great precaution.

Our client's new proprietary technology allows the treatment of approximately 80 000 tons of spent potlining every year. This process makes the spent potlining completely inert and provides a sustainable solution for the aluminum industry throughout the world.


TECHNOLOGICAL CHALLENGE

An important step in this novel process is the flotation of carbonated byproducts. For this process, the client wanted to narrow down to the best available technology to ensure good separation of the three different concentrates generated therein (refractory brick, carbon and mixed discharge). STS Canada was thus mandated for a feasibility study in order to identify the best available control technology (BACT) for this process. The following activities enabled STS to recommend the best separation technology and to identify the best foam breaker technique:

  • Characterizing the concentrate and substrate
  • Drafting an experimental design, validated by the client
  • Selecting the most appropriate technology for the application's specificity
  • Validating the technology and laboratory testing
  • Analysing the results
  • Validating of the design criteria of the selected technology

  • The filtrate clarity obtained with the first laboratory testing was not adequate for recirculation. Adding coagulants was thus necessary and eliminated the occurrence of a loop of fine material. Such a loop would have caused a build up detrimental to the flotation process and would have required a second filtration step.

    RECOMMENDED SOLUTION

    Meetings with the client for design and concept validation proved to be essential to the study, especially to define the operation and filtration strategy of the future device. This procedure gratly contributed to the optimal sizing of the equipment all the while minimizing the final solution's cost.

    RESULTS

    STS Canada recommended a pressure filter with added coagulant to the spent potling mixure, thus allowing the recirculation of the filtrate to the flotation process.

    INDUSTRY

    Chemical process

    Aluminum reduction spent lining treatment

    Flotation/Filtration

    Foam breaker

    Coagulant

    LEVEL OF INTERVENTION

    Design study

    Laboratory testing

    ESTIMATED COST

    37000$

    YEAR

    2011