Italian engineering company STC has been granted a new patent by the US Patent Office for its process for the desulphurisation of materials and/or residues containing lead sulphate employing an amino compound.
The company said it took six years to gain approval from its 2018 initial filing. Patent number is US 11946115 B2.
STC said the initial aim of the invention was to overcome the problems of the chemical cost/quality ratio and the environmental issues caused by the traditional desulphurisation process via sodium sulphate. At the same time, they wanted to capture all the advantages of the most recent desulphurisation process via ammonium carbonate, which was yet to be employed on industrial scale.
STC’s Commercial Director Alberto Bergamaschini told BEST that after laboratory testing, the inventors widened their process based on the use of an amino compound, urea, as chemical for the desulphurisation of lead paste and electrolyte neutralisation. They call the process ‘U4Lead’.
“The reaction by-product is ammonium sulphate, a well-known and valuable fertiliser also obtainable as aqueous solution for fertigation, sellable at higher price compared to the traditional desulphurisation by-product, sodium sulphate,” he said.
The inventors are CEO and technical director Giorgio La Sala, head of process engineering Francesco Scura and Gianluca Fusillo, who was part of STC’s R&D and process technologies team until 2020.
They were supported by Prof. Renato Guerriero, president of STC at the time of the invention. The company said he was one of the major Italian experts in the field of chemistry, physics, innovative materials and non-ferrous metallurgy. He was intellectual owner of over 100 patents and died in April 2019.
Bergamaschini pointed out that urea is a very cheap amino compound, easy to find, treat and handle, is chemically stable and odour-free. The U4Lead process is already in use at its used lead-acid battery recycling plant in Nigeria.
Another important advantage of the process, he said, is that urea and ammonium sulphate are both fertilisers, so any price increase or decrease is parallel.
In traditional desulphurisation, the price of sodium carbonate constantly increases without being matched by the price of sodium sulphate, which can cause financial losses for battery recyclers.
Photo: STC’s Giorgio La Sala and Francesco Scura celebrate their US patent grant. STC
