Two-step process of regeneration of acid(s) from ZrF 4 containing spent pickle liquor and recovery of zirconium metal

Abstract In this paper we describe a progressive two-step process that allows zirconium fluoride (ZrF 4 ) contained in spent baths for etched zirconium alloys to be effectively recycled on a pilot scale and produce a high purity regenerated pickling acid. In the first step, a spent pickling liquor is treated by a BaF 2 suspension to produce water insoluble Ba 2 ZrF 8 . After filtration of Ba 2 ZrF 8 more than 99.9 wt % purity pickling acid is regenerated. The precipitation mechanism of Ba 2 ZrF 8 is discussed and the role of BaF 2 particles size on the precipitation process is demonstrated. In the second step the as-precipitated Ba 2 ZrF 8 is mixed with Mg and Cu metal powders and heat-treated at 1200 °C (or above) to produce CuZr alloy ingot. The characteristics of the ingot are discussed in regard to Cu concentration and the heating temperature.