不同氧化还原环境对煤矸石污染物质释放的影响

为评价不同氧化还原环境对煤矸石污染物质释放的影响,设置处理1(充氧饱和的曝气去离子水,Eh=229mV)、处理2(煮沸30min的去离子水,Eh=250mV)两种氧化环境及处理3(添加富含有机质的过滤养殖废水,Eh=14mV)一种还原环境的水溶液做浸提剂,对煤矸石进行0～9d的连续振荡浸提试验.结果表明:在浸提初期(0～1d内),煤矸石表面已形成的氧化产物迅速溶出,使得两种氧化环境和还原环境下的煤矸石浸出液pH都迅速降低,EC、Eh及多种溶出离子浓度迅速升高,但还原环境下煤矸石浸出液中Cu、F-浓度变化不显著,且还原环境下浸出液中其他离子虽有上升但显著低于氧化环境下.随浸提时间延长(1～9d),两种氧化环境下煤矸石浸出液pH继续降低,浸出液中Fe、Mn、Cu、Zn和SO2-4、F-多种污染物质溶出数量明显增加并呈现典型的持续氧化产酸过程;而还原环境下煤矸石浸出液的pH随时间延长降低不明显,Fe、Mn、Zn等污染物质溶出数量显著低于两种氧化环境下,Cu和SO2-4的释放也受到明显抑制.说明还原环境能有效抑制煤矸石氧化产酸及多种污染物质的溶出,且显著低于氧化环境.因此,在煤矸石堆场投加有机质形成还原(厌氧)环境可进行矸石污染的原位控制及治理.

Effects of different redox environments on the release of coal gangue contaminants

The effects of different redox environments on the release of coal gangue contaminants were investigated by the batch leaching tests.The tests were conducted for 9 days in the sealed containers with three different solutions,the aerated water (deionized water with rich oxygen,condition 1),the boiled water (deionized water without oxygen,representative of condition 2) and the solution with addition of dissolved organic matter (DOM) (representative of condition3).During the leaching tests,the leachates were collected and analyzed for pH,electrical conductivity (EC),redox potential (E_h),and Fe³⁺,Mn²⁺,Cu²⁺,Zn²⁺,SO₄^2- and F^- concentrations.The results showed that,during the initial leaching phase (0~1 d),the surface oxidation products in the coal gangue were released rapidly,the pH of the coal gangue leachates under the redox conditions decreased remarkably,and concentrations of EC,E_h,and a variety of dissolved ions increased significantly.However,compared to oxidized conditions,the concentration of Cu²⁺ and F^- in the coal gangue leachates did not change significantly under the reduced environment.Although the concentration of other ions increased slightly,they were still significantly lower than those under the oxidizing environments.With the extension of leaching (1~9d),under the oxidized conditions,the coal gangue was constantly oxidized to form acidic compounds,and dissolution of Fe³⁺,Mn²⁺,Cu²⁺,Zn²⁺,SO₄^2- and F^- in the coal gangue leachates increased significantly,which is a typical acid mine drainage (AMD) formation process.However,under the reduced environment,pH did not change with time,and the leaching of Fe³⁺,Mn²⁺ and Zn²⁺ was significantly reduced,and the release of Cu²⁺,SO₄^2- and F^- was also inhibited.The data showed that the reduced environment could effectively prevent or inhibit the production of acidity and the release of contaminants in a coal gangue.It is suggested that adding organic matter into the coal gangue could be a suitable method for pollution abatement and on-site immobilization.