Hexavalent chromium removal by ferrochromium slag.
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.
Erdem
Mehmet
M
Department of Environmental Engineering, Firat University, 23279 Elaziğ, Turkey.
Altundoğan
H Soner
HS
Turan
M Deniz
MD
Tümen
Fikret
F
D002119:Calcium Carbonate; D002254:Carbonates; D002857:Chromium / Q000302:isolation & purification*; D002858:Chromium Alloys / Q000737:chemistry*; D002951:Citrates; D004338:Drug Combinations; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste / Q000517:prevention & control*; D008277:Magnesium Oxide; D009994:Osmolar Concentration; D013696:Temperature; D014867:Water
D002254:Carbonates; D002858:Chromium Alloys; D002951:Citrates; D004338:Drug Combinations; D007220:Industrial Waste; C050615:Suby's G solution; D014867:Water; D002857:Chromium; C027393:ferrochromium; C074702:chromium hexavalent ion; D008277:Magnesium Oxide; D002119:Calcium Carbonate