Li Yunjiao, Perederiy Ilya, Papangelakis Vladimiros G
Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario, Canada M5S 3E5.
J Hazard Mater. 2008 Apr 1;152(2):607-15. doi: 10.1016/j.jhazmat.2007.07.052. Epub 2007 Jul 22.
Huge quantities of slag, a waste solid product of pyrometallurgical operations by the metals industry are dumped continuously around the world, posing a potential environmental threat due to entrained values of base metals and sulfur. High temperature pressure oxidative acid leaching of nickel smelter slags was investigated as a process to facilitate slag cleaning and selective dissolution of base metals for economic recovery. Five key parameters, namely temperature, acid addition, oxygen overpressure, solids loading and particle size, were examined on the process performance. Base metal recoveries, acid and oxygen consumptions were accurately measured, and ferrous/ferric iron concentrations were also determined. A highly selective leaching of valuable metals with extractions of >99% for nickel and cobalt, >97% for copper, >91% for zinc and <2.2% for iron was successfully achieved for 20 wt.% acid addition and 25% solids loading at 200-300 kPa O(2) overpressure at 250 degrees C in 2h. The acid consumption was measured to be 38.5 kg H(2)SO(4)/t slag and the oxygen consumption was determined as 84 kg O(2)/t slag which is consistent with the estimated theoretical oxygen consumption. The as-produced residue containing less than 0.01% of base metals, hematite and virtually zero sulfidic sulfur seems to be suitable for safe disposal. The process seems to be able to claim economic recovery of base metals from slags and is reliable and feasible.
金属行业火法冶金作业产生的大量废渣——一种固体废弃物，在全球范围内持续被倾倒。由于其中含有贱金属和硫，这对环境构成了潜在威胁。研究了镍冶炼渣的高温加压氧化酸浸工艺，该工艺有助于废渣清理以及贱金属的选择性溶解，从而实现经济回收。考察了五个关键参数，即温度、酸添加量、氧气超压、固体负载量和颗粒尺寸对工艺性能的影响。准确测量了贱金属回收率、酸和氧气消耗量，还测定了亚铁/铁离子浓度。在250℃、200 - 300 kPa氧气超压、20 wt.%酸添加量和25%固体负载量的条件下，2小时内成功实现了有价金属的高选择性浸出，镍和钴的萃取率>99%，铜的萃取率>97%，锌的萃取率>91%，铁的萃取率<2.2%。测得酸消耗量为38.5 kg H₂SO₄/t废渣，氧气消耗量为84 kg O₂/t废渣，这与估计的理论氧气消耗量一致。所产生的残渣中贱金属含量低于0.01%，含有赤铁矿且硫化硫几乎为零，似乎适合安全处置。该工艺似乎能够从废渣中经济回收贱金属，并且可靠可行。
