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Zhao W.,Jiangsu Inspection and Quarantine Bureau | Feng Y.-H.,Jiangsu Inspection and Quarantine Bureau | Dai D.-Q.,Jiangsu Inspection and Quarantine Bureau
Yejin Fenxi/Metallurgical Analysis

The solid wastes such as slag, precipitator dust and oxide skin were generated in the iron and steel smelting process. Wherein, the oxide skin was a kind of solid waste that could be imported in national regulations, while the slag and precipitator dust could not be imported. The solid powders generated in iron and steel smelting process were identified. The samples were firstly judged by eyes and scanning electron microscope (SEM). For example, the appearance of slag was not block-shaped or powdered like normal natural minerals, while the precipitator dust particles were fine and light, and the oxide skin was flaky with metal luster. Then, the elements in powders were analyzed by X-ray fluorescence spectrometry (XRF). The main elements in slag were calcium, silicon, magnesium and aluminum, and the content of iron was very low. However, the content of iron in precipitator dust was very high. Meanwhile, it also contained zinc and calcium. The main element of oxide skin was iron. Finally, the phases in powders were analyzed by X-ray diffraction (XRD) technology to deduce the attribute of solid powders. The main material in slag was complex in form of CaO-MgO-Al2O3-SiO2. The main materials in precipitator dust included iron oxides and little zinc oxide. The main materials in oxide skin were also iron oxides (the content of ferrous oxide was highest). The identification methods of these three solid wastes were established by experiments, which could provide guidance to the supervision of imported solid wastes. ©, 2015, Central Iron and Steel Research Institute. All right reserved. Source

Zhao W.,Jiangsu Inspection and Quarantine Bureau | You Y.-T.,Jiangsu Inspection and Quarantine Bureau | Xu S.,Jiangsu Inspection and Quarantine Bureau | Zheng J.-M.,Jiangsu Inspection and Quarantine Bureau | Li J.-J.,Jiangsu Inspection and Quarantine Bureau
Yejin Fenxi/Metallurgical Analysis

An inductively coupled plasma mass spectrometry (ICP-MS) method was adopted for the determination of precious metal in copper concentrate in combination with fire assay preconcentration and microwave digestion method. The optimal fire assay conditions were determined: melting time, 15 min, ash blowing temperature, 960°C and ash blowing time, 1 h. In the selection of microwave digestion conditions, 10 mL of aqua regia was found to be the most optimal for dissolving precious metal. The interference of isobaric elements, polyatomic ions, refractory oxide and doubly charged ions were also discussed, and the elimination method was found out. The content of gold, palladium and platinum in a copper concentrate was discussed. The detection limit was 0.04, 0.05, and 0.1 ng/g. The relative standard deviation was 1.2%-4.0%. Source

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