Lead battery equipment maker CAM has revealed test results that confirm leady oxide from its internal water-cooled ball mill contains 100% tetragonal oxide crystals.
The Italian firm carried out X-ray analyses on leady oxide manufactured from its MOP 30 ball mill at the University of L'Aquila to certify the level of quality.
The test results were: litharge, Pb1O1 (Screen ICSD 98-006-2843), Crystal system: Tetragonal, 87,8%; and lead, Pb1 (Screen ICSD 98-009-6501), 12,1%.
CAM said it achieved 100% tetragonal oxide using its MOP ball mills, which have an internal water-led cooling system that prevents orthorhombic crystals from forming.
Tetragonal crystal structure is important as it allows the leady oxide, an ingredient of battery paste, to adhere perfectly to the grid.
When the firm’s ball mill “requests” cooling, a nozzle injects water at a certain pressure directly into the mill drum, but without coming into contact with the “oxide bed”. This system effectively prevents peaks of temperature, which can cause the formation of orthorhombic crystals, which hinder the duration of battery life.
CAM electrical manager, Francesco Marfisi, said: “In over fifty years of activity, we have learnt that one of the essential elements is to have a lead oxide which makes a paste that adheres perfectly to the grid, and we know that a tetragonal crystal structure effectively achieves this. Our ball mill produces such an oxide, which guarantees a longer life and high cranking power.
“To confirm the connection between our cooling system and the quality of oxide produced by our ball mills, we recently ordered chemical testing of a sample of lead oxide from a CAM ball mill at the University of L'Aquila’s Department of Chemical Engineering, and we were extremely pleased with the results.
“Our MOPs are the only ball mills that utilise an internal water spray cooling system which was studied back in the day and has been implemented for many years in our equipment.
BEST’s technical editor Mike McDonagh said that several companies had tried internal water-cooling of lead oxide mills, but had dropped the idea.
He said: “Their reasons for dropping it are not really well understood. If the CAM method succeeds where they have failed it is a worthy story.”
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