Patent ID: 7279036
Filing Date: 2007-10-09
Classification: C01F,C01P,C09C

Abstract:
1. A process for preparation of inorganic colourants from mixed rare earth compounds, which comprises (i) homogenising mixed rare earth compounds selected from one or more of oxide, carbonate, nitrate, fluoride, chloride of rare earth elements having atomic number in the range of 57 to 71 and having a composition of at least cerium in the range of 40-45% w/w, praseodymium in the range of 4-6% w/w, lanthanum in the range of 15-25%, neodymium in the range of 15-20% and other rare earths to a maximum of 5%, optionally mixed with not more than 40 times by weight of a compound of a metal ion selected from the group consisting of transition metal series, lanthanide/actinide series, group(III) or group(IV) of the periodic table, and/or not more than 0.2 times by weight of neutral salt either in liquid phase or solid state to obtain a homogenate; (ii) heating the homogenate obtained in step (i), followed by cooling and subsequent reduction of particle size of the resulting product to obtain inorganic colourants.