碱激发矿渣基地质聚合物固化铬渣的实验研究

发布时间：2018-04-22 07:33

本文选题：高炉矿渣 + 碱激发　；参考：《重庆大学》2015年硕士论文

【摘要】：铬渣是生产金属铬或铬盐所排放的工业废渣,因其含有毒性高的六价铬而被列为国家危险废弃物,在资源化利用前需要对铬渣进行无害化处理。地质聚合物是一种具有优越性能的无机高分子聚合物材料,对重金属离子具有良好的固化效果。利用高炉矿渣制备地质聚合物固化铬渣,不仅能减少高炉矿渣堆存产生的环境问题,还能有效阻止铬渣中铬离子的浸出行为。本论文以高炉矿渣为原材料,在碱激发剂的作用下制备了地质聚合物,并对铬渣进行了有效固化,为铬渣的处理方式进行了探索。论文用XRF、XRD分析了高炉矿渣的物化组成,表明矿渣中含有Ca O、Si O2、Al2O3等大量潜在活性物质,有利于地质聚合物的制备。对高炉矿渣的粉磨性能研究表明,12小时的粉磨时间能从物理和化学联合方式上活化矿渣,使其具有更高的活性。同时以抗压强度为指标,通过激发剂的优选、矿渣粒度的选取和正交试验得到了碱矿渣基地质聚合物的最优参数:矿渣粒度为0.053mm~0.075mm,矿渣掺入量为90wt%,水玻璃/氢氧化钠质量比为7:3,液固比为0.25,此条件下的碱矿渣基地质聚合物28天的抗压强度为50.4MPa。用铬渣等量替代矿渣的方法制备地质聚合物固化体,从力学性能上来看,铬渣掺量为10%~70%制备的固化体都能满足用于地质填埋或建筑材料的强度要求;从固化体破碎颗粒的浸出浓度来看,铬渣掺量在60%以下时,固化体六价铬浸出浓度都低于GB5085.3-2007《危险废物鉴别标准浸出毒性鉴别》中规定的限值5.0mg/L。这都表明碱矿渣地质聚合物对铬渣具有较好的固化效果,综合考虑固化体力学性能和浸出浓度,在固化效果较好的情况下可以尽量多固化铬渣的铬渣掺量为60%。通过XRD图谱分析表明碱矿渣地质聚合物和铬渣固化体的反应产物都主要是无定形态的玻璃相物质,而铬离子可能以某种非晶态形式被固封在地质聚合物固化体中;SEM分析显示碱矿渣地质聚合物与铬渣固化体内部结构都呈致密的状态,通过SEM-EDS分析表明碱矿渣地质聚合物通过水化反应生成了水化硅酸钙和铝酸钙等CSH矿物相和通过地聚合反应形成了钠沸石等沸石相,而固化体中这两项无定形产物中都固化有铬离子;IR对比分析表明固化体中的铬离子有可能参与了地质聚合物的反应过程,在反应中直接参与了平衡电荷,使Si-Al的结构发生重组,从而有效地被固定在固化体体系中。因此,明确了碱矿渣基地质聚合物固化铬渣中铬离子的固化机理为地质聚合物中无定形产物的物理固封、吸附机制和离子交换的共同作用。
[Abstract]:Chromium slag is a kind of industrial waste which is discharged from the production of metal chromium or chromium salt. It is listed as a national hazardous waste because of its high toxicity hexavalent chromium. It is necessary to treat chromium slag innocuously before resource utilization. Geopolymer is a kind of inorganic polymer material with superior performance, which has good curing effect on heavy metal ions. The preparation of geopolymer solidified chromium slag by using blast furnace slag can not only reduce the environmental problems caused by the storage of blast furnace slag, but also effectively prevent the leaching behavior of chromium ion in chromium slag. In this paper, using blast furnace slag as raw material, geopolymer was prepared under the action of alkali activator, and chromium slag was effectively solidified. The physicochemical composition of blast furnace slag was analyzed by XRF XRD. The results show that the slag contains a large number of potential active substances, such as CaOOSiO2 / Al2O3, which is beneficial to the preparation of geopolymer. The grinding performance of blast furnace slag has been studied. It is shown that 12 hours of grinding time can activate the slag in physical and chemical ways and make it have higher activity. At the same time, with the compressive strength as the index, through the optimal selection of the activator, The optimum parameters of alkaline slag base polymer were obtained by selecting slag granularity and orthogonal test: slag particle size was 0.053mm / 0.075mm, slag dosage was 90wtand, water glass / sodium hydroxide mass ratio was 7: 3, liquid-solid ratio was 0.25. under this condition, alkali slag base was obtained. The compressive strength of geopolymers for 28 days is 50.4 MPA. The solidification of geopolymer was prepared by replacing slag with chromium slag. In terms of mechanical properties, the solidified body with 10% chromium slag can meet the strength requirements of geological landfill or building materials. From the leaching concentration of broken particles of solidified body, when the content of chromium slag is below 60%, the leaching concentration of hexavalent chromium is lower than the limit value of 5.0 mg / L specified in GB5085.3-2007 < Identification Standard for Hazardous waste leaching toxicity >. These results show that the alkali slag geopolymer has a better curing effect on chromium slag. Considering the solidification physical properties and leaching concentration, the amount of chromium slag can be as much as 60% when the solidification effect is better. The XRD analysis showed that the reaction products of alkali slag geopolymer and chromium slag solidified body were mainly amorphous glass phase. The SEM analysis showed that the internal structures of alkali slag geopolymers and chromium slag solidified bodies were both dense, and chromium ions might be immobilized in some amorphous form in geopolymer solidified body, and SEM analysis showed that the internal structure of alkali slag geopolymer and chromium slag solidified body was dense. The results of SEM-EDS analysis showed that CSH phases such as calcium silicate hydrate and calcium aluminate were formed by hydration reaction of alkali slag geopolymer and zeolite phase such as sodium zeolite was formed by ground polymerization. The IR analysis of the two amorphous products showed that the chromium ions in the solidified body might be involved in the reaction process of geopolymers, which directly participated in the equilibrium charge, which resulted in the reorganization of the structure of Si-Al. Thus it is effectively fixed in the solidified body system. Therefore, the solidification mechanism of chromium ion in chromium slag solidified by alkali slag base polymer is determined to be the joint action of physical entrapment, adsorption mechanism and ion exchange of amorphous products in geopolymers.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X705

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