A new synergistic treatment of stainless steel slag and low zinc content electric arc furnace (EAF) dusts is proposed to immobilize harmful chromium in stainless steel slag. The effects of ZnFe 2 O 4 addition on the mineralogic phase and chromium leachability of CaO-SiO 2 -MgO-Al 2 O 3 -Cr 2 O 3 synthetic slag were investigated to explore the feasibility of this method. The mineralogic phases in stainless steel slag were investigated by scanning microscopy equipped with energy-dispersive spectroscopy and X-ray diffraction. The leaching concentration values of chromium and zinc were evaluated according to an alkaline digestion for the hexavalent chromium (US-EPA-3060A) and toxicity characteristic leaching procedure (TCLP, US-EPA-1311) method, respectively. It was found that all synthetic slags mainly contain α-Ca 2 SiO 4 , merwinite and spinel phase, in line with the calculation results by FactSage. The crystallization of spinel and merwinite phases was enhanced by the addition of ZnFe 2 O 4 but suppressed the precipitation of α-Ca 2 SiO 4 . It was revealed that the leaching concentration of chromium was depressed by adding ZnFe 2 O 4 and was far below the chemical limits defined in the French proposal for a criterion and evaluation methods for waste ecotoxicity (0.1 mg L −1 ). In addition, the zinc leaching concentration meets the sanitary landfill standard. The proposed synergistic treatment method was further validated on industrial stainless steel slags and EAF dusts. Experimental results indicated that the synergistic treatment method can immobilize chromium effectively and the final slags can be disposed of by sanitary landfilling or recycling as constructional materials. A schematic technologic route diagram of the synergistic treatment was also proposed.

中文翻译：

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用低锌电弧炉粉尘固定不锈钢渣中的铬

提出了一种新的不锈钢渣和低锌含量电弧炉 (EAF) 粉尘协同处理以固定不锈钢渣中的有害铬。研究了ZnFe 2 O 4 添加量对CaO-SiO 2 -MgO-Al 2 O 3 -Cr 2 O 3 合成渣矿物相和铬浸出性的影响，探讨了该方法的可行性。通过配备能量色散光谱和 X 射线衍射的扫描显微镜研究了不锈钢渣中的矿物相。铬和锌的浸出浓度值分别根据六价铬的碱性消化法（US-EPA-3060A）和毒性特征浸出程序（TCLP，US-EPA-1311）方法进行评估。发现所有合成渣主要含有α-Ca 2 SiO 4 ，merwinite 和尖晶石相，与 FactSage 的计算结果一致。ZnFe 2 O 4 的加入促进了尖晶石和墨云石相的结晶，但抑制了α-Ca 2 SiO 4 的析出。结果表明，通过添加ZnFe 2 O 4 降低了铬的浸出浓度，并且远低于法国提议的废物生态毒性标准和评估方法（0.1 mg L -1 ）中定义的化学限值。此外，锌浸出浓度符合卫生填埋标准。所提出的协同处理方法在工业不锈钢炉渣和电弧炉粉尘上得到了进一步验证。实验结果表明，协同处理方法可以有效地固定铬，最终的炉渣可以通过卫生填埋或回收作为建筑材料进行处理。并提出了协同处理的工艺路线示意图。