In the world scenario of extraction metallurgy of nuclear, refractory, based and precious metals, solvent extraction is a proven commercial technique for the purification and concentration of various leach liquors. At present this technique is being practised for large scale production of high purity metals like uranium, zirconium, hafnium, niobium, tantalum and rare earths. A beginning has been made to use this technique for the recovery of base metals such as Copper, Nickel, Cobalt and Zinc from various secondary resources. 

Among the various classes of organic solvents di(2-ethyl hexyl) phosphoric acid (D2EHPA) has emerged as a popular acidic extractant for the recovery of uranium from phosphoric acid, rare earths from mixed rare earth chlorides and Copper/Nickel/Cobalt/Zinc from sulphate solutions. The product (D2EHPA) has a purity ~ 95% with a monoester content of less than 2%. The overall yield based on PCL3 is 90%. The process of manufacture consists of following steps. 

• Reaction of alcohol with PCL3 to form diphosphite 

• Its oxidation by cholrination 

• Hydrolysis of the chloridate to technical grade D2EHPA