尾渣中砷的精细化学结构、赋存形态

本文以安徽某有色金属冶炼厂排放的尾渣为研究对象,利用扫描电镜(SEM)、X射线衍射仪(XRD)、X射线荧光光谱分析仪(XRF)和X射线光电子能谱仪(XPS)等方法对尾渣中As的精细结构进行分析,并结合Tessier提取法研究As在尾渣中的赋存形态。结果表明,尾渣中As主要与O共生以As(Ⅴ)-O金属砷酸盐形式存在,含砷矿物为砷酸铁FeAsO_(4)和拉砷铜石Cu(AsO_(4))_(2),伴有少量砷酸铝和硫化砷;总砷含量范围为0.11%—0.17%,赋存形态以残渣态为主,占90%—95%,不同形态As含量大小依次为残渣态>Fe-Mn氧化态>碳酸盐结合态>可交换态>有机结合态;pH是影响As迁移转化的重要因素之一,在环境中会积累一定水平的潜在As释放风险。

Characteristics of leaching of heavy metals from low-sulfur coal gangue under different conditions

Coal gangue is the main pollution source of mining areas.When coal gangue is stacked and recycled,the heavy metal elements contained in it are released by natural weathering and leaching,which causes damage to the surrounding ecological environment.In this study,the leaching and precipitation characteristics of heavy metals in low-sulfur coal gangue under different environmental conditions were simulated by indoor dynamic leaching experiments,which provided a theoretical basis for environmental restoration of the mining area.The conclusions are as follows:higher heavy metal content in low-sulfur coal gangue is associated with greater,leaching of heavy metals;acidic conditions promote the release of heavy metals in low-sulfur coal gangue;and more precipitation is associated with better release of heavy metals from the low-sulfur coal gangue.

Transformation of minerals at the boundary of magma-coal contact zone:case study from Wolonghu Coal Mine, Huaibei Coalfield, China

Mesozoic and Cenozoic magma activity in the Wolong Lake mining area of Huaibei is frequent,and the degree of magma intrusion into coal seams remarkable.On the one hand,magma intrusion affects the utilization of coal resources;on the other hand,the macro and trace elements in coal are redistributed to form new mineral types.This study uses the Wolong Lake magma intrusion coal seam as a research object.The mineral paragenesis for igneous rock,coke,and thermally-altered coal in an igneous intrusion zone is studied using SEM,XRD,and Raman spectroscopy.During igneous intrusion,the temperature and pressure of igneous rock metamorphose ambient low-rank coal to high-rank coal and coke.The response mechanism of minerals and trace elements to magmatic intrusion is discussed.The results are:①SEM analysis shows that ankerite and pyrite are formed from magma intrusion.Both minerals are strongly developed in the magma-coal contact zone,and less well developed in thermally-altered coal.②XRD analysis shows that igneous intrusion strongly influences the types and content of minerals in coke and thermally-altered coal.In addition to the increase amounts of ankerite and pyrite,chlorite,serpentine,and muscovite,and other secondary minerals,are generated following igneous intrusion.③Raman analysis suggests that thermally-altered coal possesses the characteristics of both pyrite and coke.Coke from the magma-coal boundary zone possesses the typical characteristics of pyrite.Igneous rock contains a mineral similar to pyrite,confirmed by both having similar Raman peaks.The scattering intensity of Ag indicates that the formation pressure of pyrite increases from thermally-altered coal via the boundary between the coke zone and the igneous rock.

安徽临涣矿区烟煤与生活污泥共燃的燃烧特性与动力学特征

以安徽淮北临涣工业园燃煤电厂煤样品和生活污水处理厂污泥样品为研究对象,采用热重分析法(TGA)对不同混合质量比条件下的煤与污泥进行了共燃实验,同时通过五种反应动力学模型研究了不同燃烧阶段煤、污泥样品共燃的动力学特征,揭示了煤和污泥的燃烧特性。研究结果表明,煤在529℃出现一个失重峰,污泥分别在140,293和430℃出现三个失重峰,表明污泥的燃烧过程分为三个失重阶段,而煤只有一个失重阶段。煤的可燃性指数与综合燃烧特性指数为11.36×10^(-6)mg/(K^(-2)·min),47.16×10^(-10)K^(-3)·min^(-2),与煤相比,污泥的可燃性指数与综合燃烧特性指数较低,分别为10.74×10^(-6)mg/(K^(-2)·min),13.04×10^(-10)K^(-3)·min^(-2)。在煤中添加污泥可以提高反应的燃烧特性,混合质量比以90(煤):10(污泥)为宜。随升温速率升高,煤与污泥的失重减少,燃烧失重速率增加,DTG曲线向高温区移动,产生热滞后现象。在固定碳燃尽阶段,混合燃料的活化能均位于两种原料之间,并且随污泥添加量增加而降低,表明污泥的添加有效提高了煤的反应活性并促进其燃烧过程。

基于非等温法的废弃环氧树脂电路板热解动力学分析

热解技术在处理废弃电路板,回收电路板中的金属,实现树脂、玻璃纤维等非金属成分的资源化方面发挥愈来愈重要的作用,但目前对于不含任何电子元件、含少量铜箔的废弃环氧树脂电路板的热解机理研究尚不明确。为阐述其热解催化作用,采用同步热分析仪和气相色谱-质谱联用(GC-MS)仪对不同升温速率(5,10,15,20℃/min)下电路板的热解特性及热解机理进行分析。结果表明,废弃电路板热解过程主要分为四个阶段:表面残余水蒸发或其他小分子散逸、环氧树脂侧链基团氧化、四溴双酚A的分解和热解残留物分解;运用Kissinger法、Flynn-Wall-Ozawa法及Friedman法等明确单一反应的热解区间并求解热分解反应动力学参数,最终得到指前因子1.14×10^(22)min^(-1)和活化能218.533 kJ/mol;采用Šatava-Šesták法和主曲线法进行机理函数对比分析,最终表明废弃环氧树脂电路板适用随机成核与增长模型:Avrami-Erofeev方程模化。研究结果可为促进热解技术的应用提供理论支撑。