Leclerc Nathalie, Meux Eric, Lecuire Jean Marie
Laboratoire d'Electrochimie des Matériaux UMR CNRS 7555, Ile du Saulcy, Université de Metz, 57045 Metz, Cedex 1, France.
J Hazard Mater. 2002 Apr 26;91(1-3):257-70. doi: 10.1016/s0304-3894(01)00394-6.
The purpose of this work was to study the feasibility at laboratory-scale of a new hydrometallurgical process for treating electric arc furnace dusts (EAFD). The proposed process is intended to extract zinc and lead from EAFD without destroying the iron oxides matrix. So, this material can be recycled by the steel industry. Independently of the origin of the samples, major mineralogical forms present in these wastes are Fe3O4, ZnO, ZnFe2O4 and PbOHCl. The proposed process consists of a hydrometallurgical treatment of wastes based on selective leaching of zinc and lead. Initially, a leaching is carried out utilizing a chelating agent, nitrilotriacetate anion (NTA3-), as the protonated form HNTA2-. Treatment of five EAFD samples for an hour at room temperature with a molar solution of reagent results in total leaching of the ZnO. In all cases the solubilized iron does not exceed 3 wt.%. The recovery of zinc and lead is performed by precipitation of metallic sulfides with a solution of Na2S4 sodium tetrasulfide 2M. These metallic sulfides can be used as metallurgical raw materials and the chelating reagent can be reused in the process after pH adjustment. The results of the normalized leaching test AFNOR X31-210 conducted on the leaching residues, shows that all the samples meet acceptance thresholds for hazardous wastes landfill. However, the residues contain a considerable amount of zinc as ZnFe2O4. The extraction of the zinc element requires the destruction of the ferrite structure. In this process, ZnFe2O4 is treated by FeCl3.6H2O. The reaction consists in a particle O2-/Cl- exchange allowing the recovery of zinc as ZnCl2 and iron as hematite Fe2O3. The separation of these products is accomplished by simple aqueous leaching. All of the zinc is extracted in a 8h treatment at 150 degrees C with a molar ratio FeCl3.6H2O/ZnFe2O4 equal to 10. Ultimate solid residues, which have been concentrated in iron, can be oriented towards the steel industry.
这项工作的目的是研究一种用于处理电弧炉粉尘（EAFD）的新型湿法冶金工艺在实验室规模的可行性。所提出的工艺旨在从电弧炉粉尘中提取锌和铅，同时不破坏铁氧化物基体。因此，这种材料可以被钢铁行业回收利用。无论样品的来源如何，这些废物中存在的主要矿物形式是Fe3O4、ZnO、ZnFe2O4和PbOHCl。所提出的工艺包括基于锌和铅的选择性浸出对废物进行湿法冶金处理。最初，使用螯合剂次氮基三乙酸阴离子（NTA3-）以质子化形式HNTA2-进行浸出。用试剂的摩尔溶液在室温下处理五个电弧炉粉尘样品一小时，导致ZnO完全浸出。在所有情况下，溶解的铁不超过3 wt.%。锌和铅的回收是通过用2M的四硫化钠溶液沉淀金属硫化物来实现的。这些金属硫化物可以用作冶金原料，并且螯合试剂在pH调节后可以在该工艺中重复使用。对浸出残渣进行的标准化浸出试验AFNOR X31 - 210的结果表明，所有样品均符合危险废物填埋的验收标准。然而，残渣中含有相当数量以ZnFe2O4形式存在的锌。锌元素的提取需要破坏铁素体结构。在这个过程中，ZnFe2O4用FeCl3·6H2O处理。该反应包括颗粒O2-/Cl-交换，从而使锌以ZnCl2形式回收，铁以赤铁矿Fe2O3形式回收。这些产物的分离通过简单的水浸出完成。在150℃下用摩尔比FeCl3·6H2O/ZnFe2O4等于10进行8小时处理，可以提取所有的锌。最终富集了铁的固体残渣可以用于钢铁行业。
