Application of zone-melting technique to metal chelate systems-XI Refining of tetrakis(di-n-propionylmethanato)zirconium(IV) from hafnium and trace amounts of some other metals.

The zone-melting method was applied to purification of tetrakis(di-n-propionylmethanato)zirconium(IV) which contained copper(II), nickel(II), cobalt(II and III), iron(III) and hafnium(IV) in the forms of their chelates with the common ligand. All minor components having effective distribution coefficients < 1 in the zirconium(IV) chelate were concentrated toward the terminal end of the refining column. When an aqueous solution of zirconium(IV) containing zinC(II) and manganese(II) in addition to the metal contaminants above was treated with di-n-propionylmethane to precipitate the chelate complexes, only zinc, iron and hafnium were found in the precipitated zirconium chelate. The first two were ettectively removed by zone-melting. Though the separation of hafnium was poorer, the technique was efficient enough for practical purposes.