【摘要】：社會(huì)的發(fā)展促使我國(guó)對(duì)能源需求日益增長(zhǎng),煤炭作為中國(guó)最豐富的能源產(chǎn)品,仍是目前最主要的能源消費(fèi)主體。煤炭燃燒后會(huì)產(chǎn)生大量的灰渣,直接堆放顯然會(huì)影響環(huán)境。實(shí)際上,煤炭既是能源、也是資源。浙江大學(xué)熱能工程研究所提出的煤炭分級(jí)轉(zhuǎn)化梯級(jí)利用技術(shù),旨在充分發(fā)掘煤炭的能源特點(diǎn)、資源屬性,有效利用煤炭產(chǎn)熱、發(fā)電、制氣,并進(jìn)一步提取灰渣中的各種有價(jià)元素。一般而言,煤灰渣中最主要的元素就是硅和鋁,若能將這兩種元素回收利用,不僅可以提高煤炭利用的經(jīng)濟(jì)性,還能保護(hù)環(huán)境、減少排放。煤矸石及其灰渣中硅鋁資源的利用,有效的途徑包括制備煅燒高嶺土和單獨(dú)提取氧化鋁或氧化硅。本文所研究的煤矸石及其灰渣,不僅氧化鋁和二氧化硅是其最主要的兩種化學(xué)組分,而且硅鋁比(Si/Al)也接近高嶺石的理論值1.18：1。因此,本文在總結(jié)目前煤灰渣中鋁硅資源利用現(xiàn)狀的基礎(chǔ)之后,研究了煤矸石及其灰渣制備煅燒高嶺土的工藝條件,為單獨(dú)提取灰渣中的鋁和硅資源,創(chuàng)新性的提出了酸浸堿熔復(fù)合法鋁硅聯(lián)產(chǎn)工藝。鋁硅聯(lián)產(chǎn)工藝流程具體為：灰渣一次硫酸酸浸→一次酸浸渣加碳酸鈉焙燒→焙燒產(chǎn)物水浸→水浸渣二次硫酸酸浸→兩次酸浸液混合并蒸發(fā)結(jié)晶→煅燒→粗氧化鋁堿浸→鋁酸鈉溶液晶種分離→氫氧化鋁煅燒→氧化鋁產(chǎn)品。通過對(duì)煤矸石、循環(huán)流化床爐渣和過水細(xì)灰三種樣品的化學(xué)成分、礦物組成、晶相結(jié)構(gòu)等分析和酸浸正交除鐵增白實(shí)驗(yàn),分析它們用于制備煅燒高嶺土的可行性,結(jié)果表明煤矸石最適合用于制備優(yōu)質(zhì)煅燒高嶺土。進(jìn)一步研究煤矸石制備煅燒高嶺土的實(shí)驗(yàn)表明,煤矸石適合用鹽酸作除鐵劑,其合適的酸浸條件為2mol/L酸濃度,40℃,2h和1：3的固液比,此時(shí)可保證浸出極少鋁的同時(shí)提高鐵浸出率,達(dá)到54.86%。穆斯堡爾譜微觀研究表明,采用化學(xué)酸浸的方法很難脫出高嶺土中的三價(jià)結(jié)構(gòu)鐵和由二價(jià)結(jié)構(gòu)鐵氧化而來的三價(jià)鐵,故酸浸除鐵應(yīng)該放在煅燒工序之前,即此煤矸石樣品宜選擇先磨后燒工藝制備煅燒高嶺土。按上述條件最終制備的煅燒高嶺土白度達(dá)到75.8%。針對(duì)灰渣提取氧化鋁,本文提出了酸浸堿熔復(fù)合法鋁硅聯(lián)產(chǎn)工藝。首先采用熱力學(xué)理論計(jì)算,證明工藝的可行性。在工藝的一次酸浸階段,同時(shí)研究了兩種煤灰渣(A和B)的一次酸浸提鋁工藝條件,對(duì)于灰渣A(Al2O3,35.67%),一次酸浸即可得到較好的鋁浸出率,最高可達(dá)97.34%。而由于灰渣B(Al2O3,27.34%)中部分鋁以晶態(tài)形式賦存,導(dǎo)致其一次酸浸的鋁浸出率只有81.72%。因此,灰渣B適用于酸浸堿熔復(fù)合法鋁硅聯(lián)產(chǎn)工藝。往灰渣B的一次酸浸渣中添加碳酸鈉焙燒活化,即可打破含鋁晶體,并生成鋁硅酸鈉和硅酸鈉礦物。實(shí)驗(yàn)確定的較優(yōu)焙燒溫度為860℃,在此溫度下不僅可以打破一次酸浸殘?jiān)械暮X晶體,還可以生成更多溶于水的硅酸鈉固體,焙燒產(chǎn)物水浸時(shí)硅的溶出率為85.98%。水浸殘?jiān)龆嗡峤䦟?shí)驗(yàn),當(dāng)硫酸濃度為5 mol/L,酸浸溫度為100℃時(shí),鋁浸出率達(dá)到99.06%。對(duì)二次酸浸法提鋁的總效率計(jì)算,結(jié)果表明提取氧化鋁的總效率達(dá)到97%以上,顯著高于常規(guī)酸法鋁浸出率。將上述兩次酸浸液混合并在115～117℃條件下蒸發(fā)結(jié)晶,得到含雜硫酸鋁晶體。硫酸鋁煅燒實(shí)驗(yàn)結(jié)果表明,較優(yōu)的煅燒條件是溫度839℃下保溫時(shí)間60min,升溫速率為5℃/min。此時(shí)可保證硫酸鋁充分分解,同時(shí)盡量減少生成不利于制備硫酸的SO2氣體。煅燒生成的粗氧化鋁經(jīng)拜耳法提純即可得到較為純凈的氧化鋁產(chǎn)品。實(shí)驗(yàn)結(jié)果表明,因鋁含量高且基本不含硅,粗氧化鋁比較適合利用拜耳法提純,氫氧化鈉的利用率更高。在母液摩爾比ak=2.99的條件下,比較合適的溶出工藝參數(shù)是母液苛性鈉(Na2Ok)濃度240g/L、反應(yīng)溫度220℃,溶出時(shí)間10 min和配料摩爾比1.75：1,此時(shí)鋁的溶出率可達(dá)97.25%。晶種分解實(shí)驗(yàn)得到鋁的分解效率為43.62%。氫氧化鋁經(jīng)過馬弗爐在1200℃高溫煅燒2h,得到的Al2O3純度為98.51%。本文提出的酸浸堿熔復(fù)合法鋁硅聯(lián)產(chǎn)工藝,在酸浸階段,可通過SO3的回收制酸實(shí)現(xiàn)硫酸的循環(huán)利用；在堿浸階段,苛性鈉溶液重復(fù)的溶出和分解,也能循環(huán)利用,故工藝物耗低。由于鋁的浸出率高達(dá)97%以上,不僅基本實(shí)現(xiàn)鋁硅完全分離,還副產(chǎn)白炭黑、硅酸鈉和高鐵渣。因此,該工藝是一種經(jīng)濟(jì)性好、資源綜合利用率高、可持續(xù)發(fā)展的環(huán)境友好型的工藝技術(shù)。
[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，

本文編號(hào)：2482689