Coromandel Internat-ional Ltd has signed a License Agreement with Shell Research Ltd for the Shell Thiogro technology to produce ammonium phosphate-based fertilisers containing elemental sulphur. This technology will be employed at Visakha-patnam unit and may extend to Kakinada plants of Coromandel, a Coroma-ndel release said here on Monday. Shell an affiliate of Royal Dutch Shell Plc., London.