尾矿及其建筑材料的重金属迁移固化的研究

发布时间：2018-02-28 00:09

本文关键词： 尾矿重金属固化迁移建材产品硅酸盐　出处：《北京交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：我国现在具有的尾矿处理方法有尾矿再选、尾矿生产建筑材料、尾矿用于制作肥料、充填矿山采空区等方式,其中利用尾矿固体废物制备建材产品,不仅可以大幅减少天然非金属矿物资源的开采,而且有利于节能减排和生态的保护。本文采用了部分承德地区的尾矿样品,用于制作建材产品,并检测产品中的重金属的浸出毒性,包括蒸养砖、混凝土、加气混凝土三种产品。本次采样范围涉及承德市6个县区共14个尾矿库,采样点共22个,按布点及不同深度采集样品数共计85个。因样品量大,工作开展有一定的时间限制,故使用X射线荧光光谱仪对尾矿样品进行化学成分分析,并根据化学测试结果经SPSS软件分析,最终确定七种样品进行后续实验。化学成分显示,尾矿中SiO_2、CaO、A1的含量较高,符合制备建筑产品时对原料成分及含量的要求。经粒径测试,发现尾矿样品的细度模数平均值均小于1.5,符合制作建材产品的粒径要求。使用微波全消解的方法检测尾矿样品中重金属的总含量,发现重金属含量最高的为锰,E1和G3两个样品的锰元素已经超过了2000 mg/kg,属于超高浓度。其次T样品为铜矿所以铜元素也较高,超过了 1000mg/kg。为深入研究产品及尾矿的生物有效性,选取了欧共体标准物质局(BCR)法进行重金属毒性浸出实验。结果显示尾矿样品在酸交换态时的浸出比例较大,在有机态、Fe-Mn氧化态时浸出比例相对较高,在残渣态时的浸出比例较小。而通过尾矿制备的建材产品的浸出实验,表明重金属在残渣态时的浸出比例增加,在酸交换态时的浸出比例减小,说明尾矿制备建材产品后,尾矿中的有害重金属被较好的固化在所制备的建材产品中。通过XRD及SEM测试,尾矿制备成产品后,蒸养砖和加气混凝土中生成了水化C-S-H凝胶及托贝莫来石、方解石等矿物,这些水化硅酸盐物质能有效的将重金属固化在晶体内部。因尾矿的原矿物的不同及蒸压养护条件的不同,各产品内部的晶体结构存在着差异,对重金属的固化效果不同。本论文的研究成果为承德地区的尾矿制备建筑产品提供了理论依据,不仅能够减少该地区的建材制造行业的原料成本,还能够解决该地区尾矿污染问题。
[Abstract]:The methods of tailings treatment in our country include tailings reprocessing, tailings producing construction materials, tailings used for making fertilizers, filling mine goaf, etc. Among them, solid waste tailings are used to prepare building materials. Not only the exploitation of natural non-metallic mineral resources can be greatly reduced, but also energy saving and emission reduction and ecological protection can be benefited. In this paper, some tailings samples from Chengde area are used to produce building materials. The leaching toxicity of heavy metals in the products was detected, including steaming bricks, concrete and aerated concrete. The sampling range involved 14 tailings reservoirs in 6 counties and districts of Chengde city, and the sampling sites were 22. A total of 85 samples were collected according to the distribution points and different depths. Due to the large amount of samples and the limited time for the work to be carried out, the chemical composition of the tailings samples was analyzed by X-ray fluorescence spectrometer. According to the analysis of chemical test results by SPSS software, seven kinds of samples were finally determined to carry out follow-up experiments. The chemical composition showed that the content of SiO2Caco _ 1 _ 1 in tailings was high, which met the requirements of raw material composition and content in the preparation of building products. It is found that the average fineness modulus of tailings is less than 1.5, which accords with the particle size requirement of building materials. The total content of heavy metals in tailings samples is determined by microwave digestion. It has been found that the manganese elements in the two samples of MNO _ 1, E _ 1 and G _ 3 have exceeded 2000 mg / kg, belonging to ultra-high concentration. The second T sample is copper mine, so the copper element is also higher than 1000 mg / kg. In order to further study the bioavailability of the products and tailings, The toxicity leaching experiments of heavy metals were carried out by the EEC Standard material (BCR) method. The results showed that the leaching ratio of tailings samples in acid exchange state was higher than that in organic Fe mn oxidized state. The leaching experiment of building materials prepared by tailings shows that the leaching ratio of heavy metals in the residue state increases, and the leaching ratio decreases in the acid exchange state, which indicates that after tailings are used to prepare building materials products, the leaching ratio of heavy metals in the residual state is higher than that in the acid exchange state. The harmful heavy metals in the tailings were well solidified in the building materials. After the tailings were prepared into products by XRD and SEM, hydrated C-S-H gels, toberamurite, calcite and other minerals were formed in steam curing bricks and aerated concrete. These hydrated silicate materials can effectively solidify heavy metals in the crystal. Due to the different raw minerals of tailings and the different curing conditions of autoclaved, the crystal structure of each product is different. The solidification effect of heavy metals is different. The research results of this paper provide a theoretical basis for tailings to prepare building products in Chengde area, which can not only reduce the raw material cost of building materials manufacturing industry in this area. It can also solve the pollution problem of tailings in this area.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD926.4

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