Journal of Geochemical Exploration ( IF 3.9 ) Pub Date : 2021-05-12 , DOI: 10.1016/j.gexplo.2021.106808 Rafał Tyszka , Anna Pietranik , Anna Potysz , Jakub Kierczak , Bernhard Schulz
Slag heaps are far from stable and evolve continuously from the time they are deposited. In the studied site (Świętochłowice, Upper Silesian Industrial Region, Poland), the major change in the slag heap has involved the formation of fine-grained strongly weathered material. Possible conditions of slag weathering, as well as any impacts of weathered material on the environment, have been evaluated by weathering experiments. The experiment simulating acid rain at adjusted pH = 4 precisely reproduced many features of the weathering transformations observed in nature, such as strong disintegration of slag material, formation of abundant Fe(hydro)oxides, silica and alumina removal, and Pb precipitation. Conversely, bioweathering with Acidithiobacillus thiooxidans often showed the opposite direction of transformations (Si and Al precipitation, Pb removal, transformations at the rims of larger slag particles), probably due to the too-aggressive low pH of the simulations. There are environmental consequences as more and more slag in the heap weathers, with fresh slag releasing mostly Zn and Ba. On the other hand, weathered slag material may release high contents of Pb, Cd, As, but only if the pH remains at 4–6. In present-day slag heap conditions, precipitation of Fe(hydro)oxides and other secondary phases diminishes toxic element mobility. However, soils and sediments surrounding the heap show high levels of contamination (up to 2500 mg/kg for Pb, up to 11,300 mg/kg for Zn, up to 120 mg/kg for Cd), which is perhaps due to leaching of weathered slag or its mechanical removal. Other contaminants include smelter emissions and high Ba and Hg components that are tentatively linked to the episode of early weathering of fresh slag.
中文翻译:
Zn Pb矿渣风化及其对环境的影响的实验模拟:酸雨,土壤溶液和微生物活性的影响
炉渣堆远非稳定状态,并且从堆放之日起便不断发展。在研究地点(波兰上西里西亚工业区Regionwiętochłowice),炉渣堆的主要变化涉及形成细粒强风化材料。矿渣风化的可能条件,以及风化材料对环境的任何影响,已经通过风化实验进行了评估。在调整的pH = 4时模拟酸雨的实验精确地再现了自然界中观察到的风化转变的许多特征,例如炉渣材料的强烈崩解,大量Fe(氢)氧化物的形成,二氧化硅和氧化铝的去除以及Pb的沉淀。相反,用硫代酸硫硫杆菌进行生物风化常常显示出相反的转变方向(Si和Al沉淀,Pb去除,较大炉渣颗粒边缘的转变),这可能是由于模拟的pH值太过激进所致。随着堆料天气中越来越多的炉渣产生环境后果,新鲜炉渣主要释放锌和钡。另一方面,风化的炉渣材料可能会释放出高含量的Pb,Cd,As,但前提是pH值保持在4-6。在当今的炉渣堆条件下,Fe(氢)氧化物和其他第二相的析出会降低有毒元素的迁移率。但是,堆周围的土壤和沉积物显示出高水平的污染(铅高达2500 mg / kg,锌高达11300 mg / kg,镉高达120 mg / kg),这可能是由于风化的浸出造成的。渣或其机械去除。