ANODE BAKING FURNACE – From OoM to Commissioning

Anode quality is crucial to the safe and optimal operation of any potline. More specifically, consistently achieving the desired baking quality while securing the anodes inventory at optimized costs is critical for the satisfactory performance of any anode plant and ultimately aluminium smelter.

Pechiney developed and started in 1958 its first open-type anode baking facility in L’Argentière in the French Alps. This new technology was firstly deployed internally in the 60’s and 70’s in plants such as Aluminium of Greece (1967). The technology started to be sold in the 70’s with the furnaces of Alro (Romania), Nalco (India) or Alcoa San Ciprian (Spain).

Since then, the design and operation have been improved over the decades thanks to innovation and the unique position of Rio Tinto to be at the same time a designer and an operator of baking furnaces. In 2020, 60 furnaces using AP design are in operation and produce approximately 7.2 million tons of baked anodes per year.

Today, AP TechnologyTM knowledge and experience in anode baking furnaces and the unique source of feedback from over 60 years of design, erection, operation and retrofit is made available through our engineering and technical services to support new projects and modernisation

Initially an anode baking furnace is designed for an anode format and a production output. When time comes to modify the anode format, as homothetie does not work for thermal laws, the furnace size and dimensions are adapted to the desired dimension and output through several modelling phases using the latest technology improvements. Various options are analysed and compared in terms of technical features, operability and costs leading to a first layout taking into account the site main constraints and finding the best compromise with the following factors: number of pit per section and number of sections per fire, number of fires, fire cycle. Thanks to the development of dedicated modelling tools, AP Technology successfully increased pit and section size over the years with a result of improved energy efficiency.

Anode baking furnace design evolution over 30 years leading to a 30% reduction in GJ/t and an anode refractory ratio of 0.7  

With the global sizing of the furnace agreed among the various players of a project, the refractory team enters into action with the proper detailed design of the furnace. Working hands in hands with process and operation experts, the refractory experts define the detailed refractory design of the furnace. Anode baking furnace is indeed a very unique and complex assembly of several thousands of refractory bricks. Experience and expertise are a “must” at this stage to define the detailed design of the fluewalls, headwalls, insulation and other parts of the furnace in order to ensure the lifetime expectancy and the baking homogeneity. With nearly 20,000 fluewalls currently in operation around the globe, AP Technology has unique experience and knowledge on this phase.

Once all the detailed engineering is finalized, bricks can be produced by refractory suppliers. The manufacturing quality, both the geometrical dimensions and the chemical and physical properties, is of critical importance to ensure a satisfactory erection and sustainable operation of the furnace. AP Technology supports its clients with the quality control at supplier premises for the dense and isolating refractory. This is currently happening for the on-going revamping of Rio Tinto Alma furnaces.

The furnace construction is another critical step. It involves an important workforce to correctly assemble more than 1 million bricks within the allocated timeframe. AP Technology supports its clients with expert resources delegated on site to follow on a day-to-day basis the erection of the furnace. This ensures the right quality is applied until the furnace is ready to be started. At this time the AP Technology operation and process team join the site to support the local team with the start-up of the firing system and the daily operations. The aim here is to reach a sustainable organization in terms of operational practices and knowledge to achieve the expected anode baking performances.

Once the furnace operation reaches its steady state, AP Technology continues to support its client through regular technical assistance activities such as audits, trainings and optimization mandates until the next retrofit of the facility.

AP Technology™ anode services range from the first studies, erection, start-up and technical assistance to retrofits and include:

  • Order of magnitude & Pre-feasibility studies
  • Technology Transfer
  • Basic engineering of the anode baking furnace building and its ancillary shops
  • Detailed engineering of the baking furnace refractory, insulation and concrete casing
  • Training at our Institut Paul Héroult
  • Support during construction, commissioning and operation
  • Refractory supply quality control services

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