分散碱性基质法处理闭坑煤矿酸性矿井水试验研究

Experimental study on treatment of acid mine water in closed pit coal mine by dispersing alkaline matrix method

贵州凯里鱼洞河区域多数关闭煤矿产生大量酸性矿山排水,造成严重水环境污染。为探讨石灰石和木屑构成的分散碱性基质系统处理闭坑煤矿酸性矿井水的效果,共进行50 d酸性矿井水处理模拟试验。采用电感耦合等离子体质谱仪(ICP-MS)测定不同时间反应进出水中Fe、Al、Mn、Zn、Cd金属离子浓度,滴定法测定酸碱度,便携式测定仪测定pH、氧化还原电位ORP和温度等。结果表明,试验结束时,分散碱性基质处理柱可有效提高酸性矿井水的pH,使出水pH维持在6以上。随着时间推移,系统的反应区段不断下移,反应结束时,可有效释放碱度的区段已移至系统的最深层,此时对应Al、Fe、Zn各元素去除效率分别可达98.58%、51.51%、35.45%,但对Mn、Cd无明显去除效果。由反应柱中固体沉淀物的X射线衍射仪(XRD)矿物成分分析、扫描电子显微镜(SEM)微观形貌分析和能量色散X-射线光谱(EDX)微观化学成分分析可得,Fe^(2+)经过氧化后形成Fe^(3+),再通过水合或沉淀作用形成氢氧化铁,氢氧化铁不稳定导致一部分会转为其水解产物(针铁矿,纤铁矿等),一部分则会通过与SO_4^(2-)的络合作用形成纤铁矾等从溶液中去除。通过对不同深度下各金属离子矿物形式的饱和度计算可得,系统表层0~8 cm还可能存在Al的相关矿物沉淀,如羟矾石,一水软铝石,一水硬铝石等。

In recent years,most of the coal mines have been closed to produce a large amount of acid mine drainage,causing serious water environmental pollution in the Yudong River area,Kaili,Guizhou.In order to explore the effect of the dispersed alkaline matrix system composed of limestone and wood chips on the treatment of acid mine water in closed pit coal mines,a total of 50 days of acid mine water treatment simulation experiments were carried out.The experiment used inductively coupled plasma mass spectrometry(ICP-MS)to measure the concentration of Fe,Al,Mn,Zn,Cd metal ions in the water in and out of the reaction at different times,the titration method to determine the acidity and alkalinity,and the portable analyzer to measure pH,redox potential ORP and temperature,etc.The results show that at the end of the experiment,the dispersed alkaline matrix treatment column can effectively increase the pH of the acidic mine water and keep the effluent above 6.With the passage of time,the reaction section of the system continues to move down.At the end of the reaction,the section that can effectively release alkalinity has moved to the deepest layer of the system.At this time,the removal efficiency of each element corresponding to Al,Fe,and Zn can reach up to 98.58%,51.51%,35.45%,but no obvious removal effect on Mn and Cd.The solid precipitate in the reaction column can be analyzed by X-ray diffractometer(XRD)mineral composition analysis,scanning electron microscope(SEM)micro-morphology analysis and energy dispersive X-ray spectroscopy(EDX)micro-chemical composition analysis.Fe2+is oxidized to form Fe3+,and then hydrated or precipitated to form iron hydroxide,but iron hydroxide is unstable,so part of it will be converted into its hydrolysate(goethite,wurtzite,etc.),and part of it will pass through with SO42-.The complexation forms fibrous iron alum and other paths to be removed from the solution.It can be obtained by calculating the saturation of each metal ion mineral form at different depths.There may also be precipitation of Al related minerals in the system surface layer 0~8 cm,such as hydroxyapatite,boehmite,diaspore,etc.