Global R&D Asturias Centre "GRID", Apartado 90, 33400 Aviles, Spain.
Department of Chemical and Environmental Engineering, University of Oviedo, c/Julián Clavería s/n, E-33071 Oviedo, Spain.
Waste Manag. 2018 Sep;79:251-259. doi: 10.1016/j.wasman.2018.07.039. Epub 2018 Aug 3.
Dust emission is one of the main environmental pollution impacts associated with steelmaking. In this sense, electrostatic precipitators (ESP) are regarded as the best available technique for treating this type of emission, thus generating two differentiated fractions: coarse and fine. Thorough chemical and structural characterization of both materials was carried out to recycle these byproducts in either the sintering process or other steps of pig iron production. Both types of dusts are crystalline heterogeneous materials mainly composed of sepiolite (MgSi(OH)·12HO), hematite (FeO) and calcite (CaCO), the coarse fraction containing low amounts of Na (0.38 ± 0.04%) and K (0.17 ± 0.02%), which adversely affect blast furnace operation. Hence, the coarse fraction is suitable for recycling, whereas the fine one presents higher concentrations of these alkali elements. Besides, textural characterization revealed that dust particulates are essentially macroporous materials, with specific surface area values of 21.6 m/g for the coarse fraction and 33.7 m/g for dust fines. In order to ensure inoffensive dumpsites, the environmental behavior associated with dust particles accumulated in disposal areas was also evaluated by performing leaching studies simulating different rainfall scenarios. It was found that the specific leaching rates of Ca, Mg, K and S varied between 0.072 ± 0.001 and 0.75 ± 0.01 µg/(g·d), whereas slower leaching rates were obtained for heavy metals (Fe, Mn and Cu), the values ranging from (1.20 ± 0.1) × 10 to (1.8 ± 0.1) × 10 µg/(g·d). These low rates indicate that the leaching of sinter dusts compounds has minimal environmental impact.
粉尘排放是炼钢过程中主要的环境污染影响因素之一。在这种情况下，静电除尘器（ESP）被认为是处理这种排放的最佳可行技术，从而产生了两种不同的细分产物：粗粉和细粉。对这两种材料进行了彻底的化学和结构特性分析，以将这些副产品回收用于烧结过程或其他生铁生产步骤。这两种类型的粉尘都是主要由海泡石（MgSi(OH)·12HO）、赤铁矿（FeO）和方解石（CaCO）组成的结晶多相材料，粗粉中含有少量的 Na（0.38±0.04%）和 K（0.17±0.02%），这会对高炉操作产生不利影响。因此，粗粉适合回收，而细粉则含有更高浓度的这些碱元素。此外，结构特性表明，粉尘颗粒本质上是大孔材料，粗粉的比表面积值为 21.6 m/g，细粉的比表面积值为 33.7 m/g。为了确保无害的垃圾场，还通过进行模拟不同降雨情景的浸出研究，评估了在处置区积累的粉尘颗粒的环境行为。结果发现，Ca、Mg、K 和 S 的特定浸出率在 0.072±0.001 和 0.75±0.01 µg/（g·d）之间变化，而重金属（Fe、Mn 和 Cu）的浸出率较慢，其值范围为（1.20±0.1）×10 到（1.8±0.1）×10 µg/（g·d）。这些低速率表明，烧结粉尘化合物的浸出对环境的影响最小。
