【作者】 孙军；

【导师】 王智；

【作者基本信息】 重庆大学 ， 材料物理与化学， 2010， 硕士

【摘要】 电解锰渣是由碳酸锰矿采用电解法生产金属锰过程中产生的滤渣,是一种含水率较高的黑色固体废弃物,对环境和居民的生活带来了严重的危害。针对其排放量大的特点,将其用于建筑材料是无害化及资源化利用比较有效的途径之一,但目前对其基本性质研究显得很缺乏,部分研究还存在一定误区。因此,对电解锰渣的基本性质,特别是涉及建材资源化利用时的硫酸盐性质进行研究显得极为重要。本文首先通过X射线衍射(XRD)、扫描电子显微镜(SEM)、差式扫描量热仪(DSC)、化学分析等手段对5种不同来源电解锰渣的基本性质进行了研究,在此基础上研究了电解锰渣中硫酸盐存在形式与溶出特性,并通过不同预处理对电解锰渣中硫酸盐性质进行了重点研究。研究结果显示:(1)电解锰渣主要以二氧化硅、三氧化二铝、氧化钙和三氧化硫等氧化物组成,是一种含硫酸盐的硅铝质材料;矿物组成以石英、莫来石、赤铁矿以及二水石膏等为主;微观结构主要是针柱状二水石膏晶体与其他物质形成的混杂交织堆积结构,整体结构疏松多孔。(2)电解锰渣热分解特性有一定的二水石膏分解峰,但峰不易辨别,二水石膏含量有限。其硫酸盐以二水硫酸钙、硫酸铵和硫酸锰等多种形态存在,其中微溶性的二水石膏约占总硫酸盐含量的60%—70%,是其主要存在形式。(3)在纯水及饱和石灰水中,电解锰渣中硫酸盐溶出均呈现早期溶解速度快,后期逐渐减缓的趋势,溶解量随灰水比呈线性增长关系。电解锰渣中总锰含量随着流水处理时间的延长表现出前7天内降低明显,降低值约为原状的14.5%,主要为水溶性锰的流失。(4)预处理剂不仅能使含水电解锰渣颗粒得到有效地分散,还能将其他形态硫酸盐转化为可建材资源化的石膏,增加量可达43%。同时,硫酸铵和硫酸锰也会随着预处理剂掺入量及放置时间增加而逐渐变少,在掺入量为7%时,电解锰渣中已不含硫酸铵,硫酸锰含量也接近零,预处理剂对电解锰渣无害化预处理效果较好。(5)煅烧电解锰渣的主要矿物成分为无水石膏和石英。电解锰渣中硫酸盐热分解是分阶段进行的,随着温度升高,各种形态硫酸盐逐渐分解,当温度达到800℃时,其中二水石膏由于与其他杂质形成低熔化合物而表现出分解温度低且呈现阶段性,当温度达到1000℃时,电解锰渣中80%的硫酸盐在前5分钟内分解完全,后期随着加热时间的延长也逐渐分解完毕。(6)随着煅烧温度升高,电解锰渣中硫酸盐溶出量逐渐降低。同时,不同煅烧时间对电解锰渣中硫酸盐的溶出量影响不显著。当预处理剂掺入量为7%,煅烧温度为200℃时,煅烧处理后电解锰渣的28d抗压强度可达2.38MPa,与未掺入预处理剂的电解锰渣相比,化学活性显著提高。电解锰渣用于建筑材料的硫酸盐特性研究结果表明,对电解锰渣的详细认识有利于其建材资源化利用。更多还原

【Abstract】 The electrolytic manganese residue (EMR) is a high water content residue from the production of manganese with manganese carbonate. It caused serious contamination to the environment and the residents’living. It has the features of the large capacity of drainage, which use to building materials is an effective way, but there is always a lack of breakthrough in the basic properties. What’s more, there are lots of misunderstandings of some studies. Therefore, it is important to study the basic properties of EMR, especially the sulfate properties which use to the utilization of building materials.The basic properties of five different EMR samples collected from several different places were investigated by x-ray diffraction(XRD), scanning electron microscope(SEM), differential scan calorific(DSC), chemical analysis and so on. On this basis, the form and dissolution characteristics of sulfate contained in EMR were studied. Then the influence of some pretreatments for EMR on the main characteristics of sulfate was primarily studied. The results showed that:(1) The main chemical compositions of EMR are SiO2、Al2O3、CaO、SO3, it is a silica-aluminum material containing sulfate, and the main minerals of EMR are quartz, mullite, hematite, and dihydrate gypsum, which were investigated by chemical analysis and XRD. The SEM results testified that the EMR has a loose and porous microstructure and stacked up by amount of needle-like crystals and sediments.(2) EMR has much obvious gypsum peak, but the peak intensity is small, which indicated that the content of dihydrate gypsum is not high. The main forms of sulfate in EMR are dihydrate calcium sulphate, ammonium sulfate and manganese sulfate, and the slightly-dissolved dihydrate calcium sulphate accounts for 60%-70% of total sulfate of EMR.(3) In water and saturated lime water, the dissolution rate of the sulfate in EMR is rapid at primary stage, and the dissolved quantity appeared linear growth with residue-water ratio. With varies running water processing time, the content of manganese decreased significantly in seven days, the reduction value is 14.5% of undisturbed EMR. The main reason is dissolution of manganese sulfate.(4) Lime is not only beneficial to the dispersion of EMR, but also helpful to the transformation of other sulfates into dihydrate gypsum, and the increasing amount of dihydrate gypsum reached 43%. The ammonium sulfate and manganese sulfate were significantly decreased with the increase of lime and standing time. The content of ammonium sulfate and manganese sulfate approximately close to zero as the system incorporated with lime of 7%. So lime has better effect for the harmless pretreatment of EMR before comprehensive utilization.(5) After heat treatment, the main mineral compositions of the EMR are anhydrite and quartz. The thermal decomposition of sulfate is realized by stages in electrolytic manganese residue, with temperature increasing, different forms sulfate gradually decomposed. When temperatures reach 800℃, dihydrate gypsum with other impurities formed low melting compounds lead to decomposition temperature decrease and show stage. When temperatures reach 1000℃, 80% of the sulfate decomposition completely within the first five minutes, with heating time gradually decomposition also completed.(6) With the calcination temperature increased , the dissolved quantity decreased. At the same time, varies calcination age affects the dissolved quantity of sulfate in electrolytic manganese residue little. Meanwhile, when the incorporation is 7% with lime, and the calcining temperature is 200℃, the mechanical properties of EMR reached the maximum of 2.38MPa at 28 day of age. Compared with undisturbed EMR, chemical activity was significantly increased.The results indicated that detailed understanding of EMR is beneficial to its used for the building materials.更多还原