冶炼钢铁过程中多种固体废物的鉴别

在钢铁的冶炼过程中,主要产生炉渣、除尘灰和氧化皮等固体废物,其中氧化皮是国家规定可以进口的固体废物,炉渣和除尘灰属于不能进口的固体废物。实验针对冶炼钢铁过程中产生的固体粉末进行鉴别,首先利用肉眼和扫描电镜(SEM)对样品进行初步判断,例如炉渣的外观不是正常天然矿物的块状或粉状,而除尘灰颗粒较细、较轻,氧化皮呈鳞片状、有金属光泽。再利用X射线荧光光谱(XRF)对制得粉末中的元素进行分析,炉渣的主要元素为钙、硅、镁和铝,铁的含量极低;而除尘灰中铁的含量很高,同时含有锌和钙;氧化皮的主要元素也是铁。最后利用X射线衍射(XRD)技术对粉末中存在的物相进行分析,从而推断出固体粉末的属性,炉渣中的主要物质是CaO-MgO-Al₂O₃-SiO₂形式存在的配合物;除尘灰中的主要物质是铁的氧化物以及一些氧化锌;氧化皮的主要物质也是铁的氧化物,其中氧化亚铁的含量高。通过实验建立了这3种固体废物的鉴别方法,对进口固体废物的监管提供指导。

Identification of various solid wastes in the iron and steel smelting process

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.