Zinc and lead recovery from zinc plant residue (ZPR) has been investigated. The residue is discarded as a cake from a Waelz kiln processing zinc-lead carbonate ores. The zinc plant residue containing 11.3% Zn, 24.6% Pb, and 8.3% Fe was blended with H 2 SO 4 and subjected to a process comprising roasting, water leaching, and finally NaCl leaching. The effect of roasting and leaching parameters on the zinc recovery was first studied. About 86% Zn was recovered after roasting at 200 8C for 30 min with an equal weight ratio of H 2 SO 4 /ZPR followed by leaching at 25 8C for 60 min with a pulp density of 20% solids. For lead recovery, the residual solid after zinc extraction was subjected to NaCl leaching. At a pulp density of 20 g/L, about 89% Pb was dissolved in 200 g/L NaCl at 25 8C in 10 min. D

The aim of this study is to demonstrate the potential of Cr(VI) generation during jigging operation applied for ferrochrome recovery from slag. The Cr(VI) concentrations of water contacted with ferrochromium slag (W/FS=10) in a closed cycle after 50 batches were found as 0.61 mg/l. Also, reduction of Cr(VI) to Cr(III) and a subsequent precipitation of Cr(III) by using ferrochrome slag (FS) in a model solution has been aimed. The effects of amount of acid, contact time, FS dosage, initial Cr(VI) concentration and temperature on the Cr(VI) reduction have been studied through the batch runs. The amount of acid has been found to be the most effective parameter affecting the Cr(VI) reduction. A 10 g/l FS dosage and 3.5 ml/l H2SO4 (5M) are sufficient to reduce all Cr(VI) in the model solution containing 10mg/l Cr(VI) and for contact time of 60 min at 25 degrees C. In reduced solutions, precipitation of metal ions has been studied by using extra FS. A 60 g/l dosage of fresh FS can precipitate all Cr(III) and Fe ions in the reduced solution. Thus, it has been demonstrated that the treatment of jigging water stream to be generated in a ferrochrome plant containing Cr(VI) can be accomplished by using ferrochromium slag and sulphuric acid. Also, it has been determined that solid residues of the process are environmentally stable by applying TCLP test.

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