Cookson Group Plc

Tam Ceramics, Inc.

John S Campbell

Michael E Foulkes

Brian N Baker

Anil Katyal

A curing composition for curing a polysulphide polymer, which composition comprises as the curing agent sodium birnessite, Na.sub.4 Mn.sub.14 O.sub.27.9H.sub.2 O. A process for the preparation of sodium birnessite comprises the steps of adding excess in the range of from 25% to 225% of a solution of sodium hydroxide to a solution of manganese (II) chloride or manganese (II) sulphate to form a slurry of manganese (II) hydroxide and passing air free of carbon dioxide therethrough for at least 3 hours or oxygen for 1.5 hours, these steps being carried out at ambient temperature.

Curing composition for polysulphide polymers

A process for the production of zirconium tetrachloride from dissociated zircon in which gaseous chlorine is passed through pellets consisting of ground dissociated zircon, carbon and a binder at a temperature in the range of from 450.degree. to 800.degree. C. The zirconium tetrachloride produced contains less than about 0.22% by weight, calculated as SiO.sub.2, of silicon tetrachloride.

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Gerrards Cross, United Kingdom

John S Campbell