Aluminum Reduction Technology: Environment (Material and Equipment)
Sponsored by: TMS Light Metals Division, TMS: Aluminum Committee
Program Organizers: Nadia Ahli, Emirates Global Aluminium; Nancy Holt, Hydro Aluminium As
Thursday 8:30 AM
March 18, 2021
Room: RM 28
Location: TMS2021 Virtual
Session Chair: Shane Polle, EGA
8:30 AM
Low and High Voltage PFC Slope Coefficient Monitoring during Pot Start-up: Christine Dubois1; Luis Espinoza-Nava1; 1Alcoa
Latest intergovernmental panel on climate change update includes a methodology to estimate perfluorocarbon (PFC) emissions generated during reduction cell start-up. Alcoa has sampled PFC emissions to estimate tier 3 PFC emission slope from aluminum cell operation including cell start-up, for low and high voltage PFC emissions. Results obtained show that cell start-up methodology will impact the PFC emission slope. Thus, some aluminum smelter will have similar PFC emission slope coefficients for cell start-up and older cell in operation, while others will have different PFC emission slope coefficients for start-up and older cell. Low voltage PFC emissions from pot start-up are still under investigation but summary results are presented in this paper. Based on this, Alcoa smelters in Canada have put in place a procedure to analyze and use different slopes or integrate both results into one slope depending on the number of pot started during a given period of time.
8:50 AM
Latest Developments in GTC Design to Reduce Fluoride Emissions: Philippe Martineau1; Youssef Joumani1; Bassam Hureiki1; Jérémy Neveu1; Fabienne Virieux1; 1Fives
The emission of fluorine from aluminium smelters to the atmosphere remains a serious environmental concern and requires special considerations during GTC engineering phase for greenfield or creeping projects. In order to achieve the lowest emission of fluorides, Fives has developed several innovations and demonstrated their benefits at industrial scale: • A dedicated flow-control valve installed at pots outlet ducts allowing the adjustment of the pot gas suction with cell operation requirements, • An alumina recirculation gas scrubber named OZEOS designed to allow adjustments of the alumina residence time optimizing the HF adsorption, • The Fives Solios patented process of alumina Cascade with specific Air Gravity Conveyor ensuring an improved scrubbing efficiency in very warm areas, • A digital solution combining multi-locations measurements of hydrogen fluoride (potroom & stack).The current paper describes the R&D works, the industrial implementation and the industrial results obtained thanks to these innovations.
9:10 AM
Process and Environmental Aspects of Applying Unshaped Carbon Materials for Cell Lining Purposes: Alexander Proshkin1; Vitaly Pingin1; Viktor Mann1; Aleksey Zherdev1; Andrey Sbitnev1; Yury Shtefanyuk1; 1RUSAL
The number of RUSAL’s cells with un-shaped, eco-friendly materials of the insulation and part of the refractory – materials that can be re-cycled in the amount of no less than 80% – has been increased up to 1,600. Because of said materials’ lower density and re-cycling, it is possible to reduce the amount of SPL requiring landfilling. The paper elaborates on technologies to both expand and improve pyrolysis products from carbon raw materials, so that products from lignite, charcoal and grass culms can be used as thermal insulation in cells with un-shaped lining materials.The paper provides the results of researching both earlier-tested and new un-shaped carbon materials. New materials are compared with earlier-tested and conventional lining materials, in terms of efficiency and performance. Additional information is given about the use of such materials, including equipment for their installation. Autopsy results are provided for different-age cells lined with un-shaped materials.
9:30 AM
Characterisation of Powders-precondition for Plant Engineering: Peter Hilgraf1; Arne Hilck2; Jan Paepcke2; 1HAW, Hamburg, University of Applied Science; 2Claudius Peters Projects GmbH
When a process modification envolves a new, or a partly unknown material, it is very important to establish a good basis for the material characteristics. If a material sample is available it is possible to measure various material parameters and characterize the material perfetly. An accurate measurement of only a few material parameters will allow for a better selection of the necessary process steps for the material handling and selection of the right storage equipment.In this paper different ways to characterize powder and bulk material are introduced. A system to select the right storage and handling equipment is discussed.
9:50 AM
Gas Treatment in the GE Pot Integrated ABART Modules (PIA): Anders Sorhuus1; Håvard Olsen1; Eivind Holmefjord1; Roger Theodorsen1; Mikkel Sørum1; 1GE Power
A potline for production of aluminium typically comprise several hundred electrolytic pots with one or two large centralized gas treatment centers (GTCs) located in the middle of the courtyard. An average fluoride flow is distributed back to each pot due to the mixing of the process gases before entry to the large centralized GTC. However, since pots are behaving differently each with unique HF evolving dynamics, a different approach is explored with dedicated PIA modules where the adsorbed fluoride is recovered back to the same pot.The PIA concept integrates with the pot controllers to optimize the feed of alumina by demand into the gas adsorption reactors. The PIA concept also includes a high degree of prefabrication into container sized modules that are designed to be suspended directly from the pot room columns.
10:10 AM
New Phase in Upgrade of Søderberg Technology at RUSAL’s Smelters: Viktor Buzunov1; Viktor Mann2; Vitaliy Pingin1; Aleksey Zherdev1; Maksim Kazantsev1; Andrey Pinaev1; Yuriy Bogdanov1; 1Rusal Etc; 2UC RUSAL
RUSAL is in phase 2 of upgrading its Søderberg technology. After a successful upgrade in the Krasnoyarsk smelter, new designs (EcoSøderberg) are now being deployed across the Bratsk, Irkutsk, Novokuznetsk and Volgograd smelters. The EcoSøderberg includes: energy-efficient cathode; point feeding; innovative gas removal system (without burners) where CO-to-CO2 after-burning occurs under the skirt; anode paste/SHP based on eco-pitch (low PAHs); continuous digital control over the environmental performance of cells, including pot-without-seal warnings; new potroom vehicles with automated control; shorter pot tending operations; and two-stage exhaust gas treatment.The above helped to reduce benzo(a)pyrene emissions by more than 50%. Other emissions reduced to the average of pre-baked technologies, or even lower. Low (compared to conversion to PB) upgrade costs and considerable improvements in cell performance should also be noted. RUSAL continues its efforts to minimize/’reduce to zero’ PAH and other emissions and develop a fully automatic system for environmental control.
10:30 AM Question and Answer Period