Inert anodes for aluminum smelting

Technical Report · Sat Feb 01 04:00:00 EST 1986

OSTI ID:6734134

Weyand, J D; Ray, S P; Baker, F W; DeYoung, D H; Tarcy, G P

The use of nonconsumable or inert anodes for replacement of consumable carbon anodes in Hall electrolysis cells for the production of aluminum has been a technical and commercial goal of the aluminum industry for many decades. This report summarizes the technical success realized in the development of an inert anode that can be used to produce aluminum of acceptable metal purity in small scale Hall electrolysis cells. The inert anode material developed consists of a cermet composition containing the phases: copper, nickel ferrite and nickel oxide. This anode material has an electrical conductivity comparable to anode carbon used in Hall cells, i.e., 150 ohm {sup {minus}1}cm{sup {minus}1}. Metal purity of 99.5 percent aluminum has been produced using this material. The copper metal alloy present in the anode is not removed by anodic dissolution as does occur with cermet anodes containing a metallic nickel alloy. Solubility of the oxide phases in the cryolite electrolyte is reduced by: (1) saturated concentration of alumina, (2) high nickel oxide content in the NiO-NiFe{sub 2}O{sub 4} composition, (3) lowest possible cell operating temperature, (4) additions of alkaline or alkaline earth fluorides to the bath to reduce solubilities of the anode components, and (5) avoiding bath contaminants such as silica. Dissolution rate measurements indicate first-order kinetics and that the rate limiting step for dissolution is mass transport controlled. 105 refs., 234 figs., 73 tabs.

• Research Organization: Aluminum Co. of America, Alcoa Center, PA (USA). Alcoa Labs.
• Sponsoring Organization: DOE/FE
• DOE Contract Number: FC07-80CS40158
• OSTI ID: 6734134
• Report Number(s): DOE/CS/40158-20; ON: DE90014989
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
320303* -- Energy Conservation
Consumption
& Utilization-- Industrial & Agricultural Processes-- Equipment & Processes
36 MATERIALS SCIENCE
360101 -- Metals & Alloys-- Preparation & Fabrication
360201 -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360603 -- Materials-- Properties
360604 -- Materials-- Corrosion
Erosion
& Degradation
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400800 -- Combustion
Pyrolysis
& High-Temperature Chemistry
ALUMINIUM
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
ANODES
CARBON
CERMETS
CHALCOGENIDES
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
CHEMISTRY
COATINGS
COMPOSITE MATERIALS
CONCENTRATION RATIO
CONTROL
CORROSION
DOCUMENT TYPES
ELECTROCHEMISTRY
ELECTRODES
ELECTROLYTES
ELEMENTAL MINERALS
ELEMENTS
EVALUATION
FABRICATION
GRAPHITE
MATERIALS
MEASURING METHODS
MECHANICAL PROPERTIES
METALS
MINERALS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PERFORMANCE TESTING
POWDERS
PROCESS CONTROL
PROGRESS REPORT
REFRACTORIES
RETROFITTING
SMELTING
TECHNOLOGY ASSESSMENT
TESTING