Particle size liquid color concentrates

Other methods for the preparation of rare earth cyanides are the reaction of metallic R with Hg(CN)2 in liquid ammonia and the precipitation with HCN in an ammonia solution of metallic Eu and Yb (McColm and Thompson, 1972). The problem with the first of these methods is the difficulty of removing metallic Hg and the possible excess of Hg(CN)2- The precipitation method has been extended to rare earths insoluble in ammonia, in which case the reaction is effected by electrolysis at —63°C in a concentrated NH4CN-NH3 solution, using rare earth and platinum electrodes. In all cases the crystallinity is poor and the particle size of the product is small. The colors of some rare earth cyanides already synthesized are presented in table 30. 

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