State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China.
College of Zijin Mining, Fuzhou University, Fuzhou 350000 China.
Waste Manag. 2022 Jan 1;137:50-60. doi: 10.1016/j.wasman.2021.10.019. Epub 2021 Oct 31.
A significant amount of coal fly ash is generated and this type of waste material causes severe environmental hazards. Metal (Al and Fe) extraction from coal fly ash is beneficial to the resource utilization of waste coal fly ash. However, the coexistence of Al and Fe in coal fly ash means that the separation of Al and Fe is required, which is a key and difficult step to prepare high value-added products from coal fly ash. This work presents a novel electrolysis method to alter the charge sequence of Al, Fe, and HO, leading to a process different from their natural tendency for simultaneous separation of Fe and Al, and extraction of Fe. The single iron removal efficiency was 43.48%, and the aluminum extraction efficiency was <0.30% under optimal conditions. The iron product had a purity of 98.3 wt% Fe, 0.45 wt% Al, and 0.18 wt% S. This process occurs without chemical additions and expensive membranes, avoiding impurity introduction, slag generation, and membrane limitations. Fe(s), H(g), Al(SO)(aq), and O(g) are the main products during the electrolysis. Flake Fe is selectively produced instead of colloidal Fe(OH). Fe is a magnetic substance and is easier to remove from the solution by magnets than colloidal Fe(OH). H is a green fuel. Wastewater (Al(SO)(aq)) can be directly used to further extract alumina. Therefore, this study provides an alternative method of zero pollution discharge for simultaneous separation of Fe and Al, and extraction of Fe from coal fly ash leachate.
产生了大量的粉煤灰，这种类型的废物对环境造成严重危害。从粉煤灰中提取金属（Al 和 Fe）有利于废物粉煤灰的资源利用。然而，粉煤灰中 Al 和 Fe 的共存意味着需要分离 Al 和 Fe，这是从粉煤灰中制备高附加值产品的关键和难点步骤。本工作提出了一种新颖的电解方法来改变 Al、Fe 和 HO 的荷电顺序，导致与它们同时分离 Fe 和 Al 以及提取 Fe 的自然趋势不同的过程。在最佳条件下，单一铁去除效率为 43.48%，铝提取效率<0.30%。铁产物的纯度为 98.3wt%Fe、0.45wt%Al 和 0.18wt%S。该过程无需添加化学物质和昂贵的膜，避免了杂质的引入、渣的生成和膜的限制。在电解过程中主要生成 Fe(s)、H(g)、Al(SO)(aq)和 O(g)。而是选择性地生成片状 Fe，而不是胶体 Fe(OH)。Fe 是一种磁性物质，用磁铁从溶液中去除比胶体 Fe(OH)更容易。H 是一种绿色燃料。废水（Al(SO)(aq)）可直接用于进一步提取氧化铝。因此，本研究为粉煤灰浸出液中同时分离 Fe 和 Al 以及提取 Fe 提供了一种零污染排放的替代方法。
