The Antimony Price Rise Crisis – a lower cost pathway for lead acid batteries
Microtex batteries like all industrial lead acid battery companies has been hit by rising material and energy costs. By use of sound metallurgical principles and understanding of battery chemistry from pasting through to formation, they have enabled sufficient cost savings to overcome the additional antimony costs and have become even more competitive in today’s markets. The higher antimony price since last year, can more than double the average positive tubular plate cost. Removing or reducing antimony in industrial positive grids presents problems of material strength with implications for processability, corrosion and cycle life. In order to find alternative alloys, it was necessary to make a detailed examination of the metallurgy of the mechanisms of creep strength, UTS and YS in order to enhance the properties of alternative, lower cost lead-based alloys.
Detailed processing and performance trials were performed using these principles to enable new lower cost alloys to be substituted by changing processing methods. These include:
Metallurgical: Casting conditions, post casting treatment, effects of flash drying and curing on mechanical properties. UTS and YS measurements of new grid alloys.
Electrochemical: Capacity tests, positive grid corrosion.
Mechanical properties of new alloys were enhanced to match or exceed existing Sb alloys. Energy savings of around 5% were recorded for the VRLA formation process.
A detailed review of the metallurgical and electrochemical principles that affect the processing, plus in-service characteristics, and subsequent results are also included.
Additional work on reducing energy formation costs by up to 15%, particularly by applying new, more efficient formation principles to VRLA batteries, are discussed.
Results include:
Formation energy with new algorithms, mechanical properties of grid alloys, capacity and corrosion tests.
Further work:
Refinement of alloy secondary elements and further investigation of VRLA electrolyte resistance mechanisms to reduce propagation of parasitic reactions.
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