煤矸石及其灰渣中铝硅资源化利用的试验研究
发布时间：2019-05-22 04:45
【摘要】：社会的发展促使我国对能源需求日益增长,煤炭作为中国最丰富的能源产品,仍是目前最主要的能源消费主体。煤炭燃烧后会产生大量的灰渣,直接堆放显然会影响环境。实际上,煤炭既是能源、也是资源。浙江大学热能工程研究所提出的煤炭分级转化梯级利用技术,旨在充分发掘煤炭的能源特点、资源属性,有效利用煤炭产热、发电、制气,并进一步提取灰渣中的各种有价元素。一般而言,煤灰渣中最主要的元素就是硅和铝,若能将这两种元素回收利用,不仅可以提高煤炭利用的经济性,还能保护环境、减少排放。煤矸石及其灰渣中硅铝资源的利用,有效的途径包括制备煅烧高岭土和单独提取氧化铝或氧化硅。本文所研究的煤矸石及其灰渣,不仅氧化铝和二氧化硅是其最主要的两种化学组分,而且硅铝比(Si/Al)也接近高岭石的理论值1.18：1。因此,本文在总结目前煤灰渣中铝硅资源利用现状的基础之后,研究了煤矸石及其灰渣制备煅烧高岭土的工艺条件,为单独提取灰渣中的铝和硅资源,创新性的提出了酸浸碱熔复合法铝硅联产工艺。铝硅联产工艺流程具体为：灰渣一次硫酸酸浸→一次酸浸渣加碳酸钠焙烧→焙烧产物水浸→水浸渣二次硫酸酸浸→两次酸浸液混合并蒸发结晶→煅烧→粗氧化铝碱浸→铝酸钠溶液晶种分离→氢氧化铝煅烧→氧化铝产品。通过对煤矸石、循环流化床炉渣和过水细灰三种样品的化学成分、矿物组成、晶相结构等分析和酸浸正交除铁增白实验,分析它们用于制备煅烧高岭土的可行性,结果表明煤矸石最适合用于制备优质煅烧高岭土。进一步研究煤矸石制备煅烧高岭土的实验表明,煤矸石适合用盐酸作除铁剂,其合适的酸浸条件为2mol/L酸浓度,40℃,2h和1：3的固液比,此时可保证浸出极少铝的同时提高铁浸出率,达到54.86%。穆斯堡尔谱微观研究表明,采用化学酸浸的方法很难脱出高岭土中的三价结构铁和由二价结构铁氧化而来的三价铁,故酸浸除铁应该放在煅烧工序之前,即此煤矸石样品宜选择先磨后烧工艺制备煅烧高岭土。按上述条件最终制备的煅烧高岭土白度达到75.8%。针对灰渣提取氧化铝,本文提出了酸浸碱熔复合法铝硅联产工艺。首先采用热力学理论计算,证明工艺的可行性。在工艺的一次酸浸阶段,同时研究了两种煤灰渣(A和B)的一次酸浸提铝工艺条件,对于灰渣A(Al2O3,35.67%),一次酸浸即可得到较好的铝浸出率,最高可达97.34%。而由于灰渣B(Al2O3,27.34%)中部分铝以晶态形式赋存,导致其一次酸浸的铝浸出率只有81.72%。因此,灰渣B适用于酸浸碱熔复合法铝硅联产工艺。往灰渣B的一次酸浸渣中添加碳酸钠焙烧活化,即可打破含铝晶体,并生成铝硅酸钠和硅酸钠矿物。实验确定的较优焙烧温度为860℃,在此温度下不仅可以打破一次酸浸残渣中的含铝晶体,还可以生成更多溶于水的硅酸钠固体,焙烧产物水浸时硅的溶出率为85.98%。水浸残渣做二次酸浸实验,当硫酸浓度为5 mol/L,酸浸温度为100℃时,铝浸出率达到99.06%。对二次酸浸法提铝的总效率计算,结果表明提取氧化铝的总效率达到97%以上,显著高于常规酸法铝浸出率。将上述两次酸浸液混合并在115～117℃条件下蒸发结晶,得到含杂硫酸铝晶体。硫酸铝煅烧实验结果表明,较优的煅烧条件是温度839℃下保温时间60min,升温速率为5℃/min。此时可保证硫酸铝充分分解,同时尽量减少生成不利于制备硫酸的SO2气体。煅烧生成的粗氧化铝经拜耳法提纯即可得到较为纯净的氧化铝产品。实验结果表明,因铝含量高且基本不含硅,粗氧化铝比较适合利用拜耳法提纯,氢氧化钠的利用率更高。在母液摩尔比ak=2.99的条件下,比较合适的溶出工艺参数是母液苛性钠(Na2Ok)浓度240g/L、反应温度220℃,溶出时间10 min和配料摩尔比1.75：1,此时铝的溶出率可达97.25%。晶种分解实验得到铝的分解效率为43.62%。氢氧化铝经过马弗炉在1200℃高温煅烧2h,得到的Al2O3纯度为98.51%。本文提出的酸浸碱熔复合法铝硅联产工艺,在酸浸阶段,可通过SO3的回收制酸实现硫酸的循环利用；在碱浸阶段,苛性钠溶液重复的溶出和分解,也能循环利用,故工艺物耗低。由于铝的浸出率高达97%以上,不仅基本实现铝硅完全分离,还副产白炭黑、硅酸钠和高铁渣。因此,该工艺是一种经济性好、资源综合利用率高、可持续发展的环境友好型的工艺技术。
[Abstract]:The development of society has led to the increasing demand for energy, and coal as the most abundant energy product in China, and is still the main body of energy consumption at present. After the coal is burned, a large amount of ash and ash can be generated, and the direct piling obviously affects the environment. In fact, coal is both a source of energy and a resource. The coal classification and conversion step utilization technology proposed by the Institute of Thermal Energy Engineering of Zhejiang University is designed to fully exploit the energy characteristics and resource attributes of the coal, effectively utilize the coal production, power generation, gas production, and further extract various valuable elements in the ash. In general, the most important element in the coal ash slag is silicon and aluminum, and if the two elements can be recycled, the invention not only can improve the economy of the coal utilization, but also can protect the environment and reduce the emission. The effective method of the utilization of the silicon-aluminum resource in the coal-fired stone and its ash-ash includes the preparation of the sintered kaolin and the separate extraction of alumina or silicon oxide. The coal-fired stone and its ash, not only alumina and silicon dioxide, are the two main chemical components, but also the silicon-to-aluminum ratio (Si/ Al) is about 1.18:1. On the basis of summarizing the present situation of the utilization of the aluminum-silicon resources in the present coal ash slag, this paper studies the technological conditions of the preparation of the coal-fired kaolin from the coal-fired stone and its ash, and provides an innovative method for co-production of the aluminum-silicon co-production process of the acid-immersion base-melting composite method for the extraction of the aluminum and silicon resources in the ash. The process flow of the aluminum-silicon co-production is as follows: A primary acid leaching residue of the ash and the ash is immersed in the primary acid leaching slag and the sodium carbonate is roasted to be roasted, the water is soaked in the water leaching residue secondary sulfuric acid leaching solution for twice acid leaching solution to be mixed and evaporated and crystallized to separate the aluminum hydroxide and the aluminum hydroxide to be fired into the aluminum oxide product. Through the analysis of the chemical composition, the mineral composition, the crystal phase structure and the like of the three samples of the coal-fired stone, the circulating fluidized bed slag and the over-water fine ash, and the acid-immersed orthogonal deironing and whitening experiment, the feasibility of the preparation of the coal-fired kaolin is analyzed, The results show that the coal-fired stone is most suitable for the preparation of high-quality sintered kaolin. The experimental results of the further study on the preparation of the coal-fired kaolin from the coal-fired stone show that the coal-fired kaolin is suitable for the use of hydrochloric acid as the iron-removing agent, and the appropriate acid-leaching conditions are 2 mol/ L acid concentration,40 DEG C,2 h and 1:3 solid-liquid ratio, and the leaching rate of the iron can be increased at the same time, and the iron leaching rate can be increased to 54.86%. The Mossbauer study shows that the method of chemical acid leaching is difficult to get rid of the trivalent iron in the kaolin and the trivalent iron which is oxidized by the ferrous structure iron, so that the acid leaching and iron removal should be carried out before the burning step, In other words, the coal-fired stone sample should be prepared by the pre-grinding and post-grinding process to prepare the sintered kaolin. The whiteness of the sintered kaolin prepared according to the above conditions reached 75.8%. In order to extract the alumina from ash and slag, this paper presents an aluminum-silicon co-production process of acid-dip-base fusion. The thermodynamic theory is used to calculate the feasibility of the process. In one acid leaching stage of the process, the conditions of primary acid leaching of two kinds of coal ash residues (A and B) were studied, and for ash A (Al2O3, 35.67%), a good leaching rate of aluminum was obtained by one-time acid leaching, up to 97.34%. The aluminum leaching rate of the primary acid leaching is only 81.72% due to the occurrence of some of the aluminum in the ash B (Al2O3, 27.34%) in the crystalline form. Therefore, the ash B is suitable for the acid-leaching and alkali-melting composite aluminum-silicon co-production process. Adding sodium carbonate to the primary acid leaching residue of the ash B for roasting and activation, so that the aluminum-containing crystal can be broken, and the aluminum sodium silicate and the sodium silicate mineral can be generated. The optimum roasting temperature is 860 鈩，
本文编号：2482689
[Abstract]:The development of society has led to the increasing demand for energy, and coal as the most abundant energy product in China, and is still the main body of energy consumption at present. After the coal is burned, a large amount of ash and ash can be generated, and the direct piling obviously affects the environment. In fact, coal is both a source of energy and a resource. The coal classification and conversion step utilization technology proposed by the Institute of Thermal Energy Engineering of Zhejiang University is designed to fully exploit the energy characteristics and resource attributes of the coal, effectively utilize the coal production, power generation, gas production, and further extract various valuable elements in the ash. In general, the most important element in the coal ash slag is silicon and aluminum, and if the two elements can be recycled, the invention not only can improve the economy of the coal utilization, but also can protect the environment and reduce the emission. The effective method of the utilization of the silicon-aluminum resource in the coal-fired stone and its ash-ash includes the preparation of the sintered kaolin and the separate extraction of alumina or silicon oxide. The coal-fired stone and its ash, not only alumina and silicon dioxide, are the two main chemical components, but also the silicon-to-aluminum ratio (Si/ Al) is about 1.18:1. On the basis of summarizing the present situation of the utilization of the aluminum-silicon resources in the present coal ash slag, this paper studies the technological conditions of the preparation of the coal-fired kaolin from the coal-fired stone and its ash, and provides an innovative method for co-production of the aluminum-silicon co-production process of the acid-immersion base-melting composite method for the extraction of the aluminum and silicon resources in the ash. The process flow of the aluminum-silicon co-production is as follows: A primary acid leaching residue of the ash and the ash is immersed in the primary acid leaching slag and the sodium carbonate is roasted to be roasted, the water is soaked in the water leaching residue secondary sulfuric acid leaching solution for twice acid leaching solution to be mixed and evaporated and crystallized to separate the aluminum hydroxide and the aluminum hydroxide to be fired into the aluminum oxide product. Through the analysis of the chemical composition, the mineral composition, the crystal phase structure and the like of the three samples of the coal-fired stone, the circulating fluidized bed slag and the over-water fine ash, and the acid-immersed orthogonal deironing and whitening experiment, the feasibility of the preparation of the coal-fired kaolin is analyzed, The results show that the coal-fired stone is most suitable for the preparation of high-quality sintered kaolin. The experimental results of the further study on the preparation of the coal-fired kaolin from the coal-fired stone show that the coal-fired kaolin is suitable for the use of hydrochloric acid as the iron-removing agent, and the appropriate acid-leaching conditions are 2 mol/ L acid concentration,40 DEG C,2 h and 1:3 solid-liquid ratio, and the leaching rate of the iron can be increased at the same time, and the iron leaching rate can be increased to 54.86%. The Mossbauer study shows that the method of chemical acid leaching is difficult to get rid of the trivalent iron in the kaolin and the trivalent iron which is oxidized by the ferrous structure iron, so that the acid leaching and iron removal should be carried out before the burning step, In other words, the coal-fired stone sample should be prepared by the pre-grinding and post-grinding process to prepare the sintered kaolin. The whiteness of the sintered kaolin prepared according to the above conditions reached 75.8%. In order to extract the alumina from ash and slag, this paper presents an aluminum-silicon co-production process of acid-dip-base fusion. The thermodynamic theory is used to calculate the feasibility of the process. In one acid leaching stage of the process, the conditions of primary acid leaching of two kinds of coal ash residues (A and B) were studied, and for ash A (Al2O3, 35.67%), a good leaching rate of aluminum was obtained by one-time acid leaching, up to 97.34%. The aluminum leaching rate of the primary acid leaching is only 81.72% due to the occurrence of some of the aluminum in the ash B (Al2O3, 27.34%) in the crystalline form. Therefore, the ash B is suitable for the acid-leaching and alkali-melting composite aluminum-silicon co-production process. Adding sodium carbonate to the primary acid leaching residue of the ash B for roasting and activation, so that the aluminum-containing crystal can be broken, and the aluminum sodium silicate and the sodium silicate mineral can be generated. The optimum roasting temperature is 860 鈩，
本文编号：2482689
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