【摘要】：我國的鋁土礦有98%以上屬于一水硬鋁石型,一水硬鋁石在浸出方面難度很大,這是因為一水硬鋁石型的晶型很完整,晶格能很大,其化學(xué)活性很差。由于用鋁行業(yè)的迅速發(fā)展,導(dǎo)致我國的優(yōu)質(zhì)鋁土礦資源減少,大部分鋁土礦的鋁硅比為3~6,很難滿足拜耳法處理鋁土礦的要求,嚴(yán)重制約了我國的氧化鋁工業(yè)發(fā)展,用拜耳法來處理低鋁硅比的一水硬鋁石鋁型鋁土礦時,能耗較高,流程復(fù)雜,成本較高。本文用硫酸法處理中低品位的一水硬鋁石型鋁土礦,系統(tǒng)的研究了鋁土礦硫酸法溶出的工藝條件;并在此基礎(chǔ)上,對溶出液中的金屬雜質(zhì)進(jìn)行去除,使其雜質(zhì)含量降到了很低的水平;以除雜后的產(chǎn)物為原料,制取了氧化鋁氣凝膠,并初步研究了其制備工藝。研究結(jié)果如下:(1)研究了研磨和焙燒等預(yù)處理手段對氧化鋁溶出的影響,并分析了焙燒鋁土礦的機理。預(yù)處理的條件分別為鋁土礦粒度100μm,焙燒溫度650℃,焙燒時間為60min。(2)通過單因素實驗研究了硫酸法溶出氧化鋁的影響因素,并用正交實驗優(yōu)化了工藝,最佳工藝為:溶出反應(yīng)溫度180℃、硫酸濃度90%、液固比為8:1、溶出反應(yīng)時間120min,在此條件下,氧化鋁的溶出率達(dá)到90.23%。(3)溶出液為硫酸鋁溶液,濃縮結(jié)晶分離出硫酸鋁,分析可知硫酸鋁中含有Al、Fe、Mg、Si、Ca、Na、K等元素。對鋁土礦和溶出液硫酸鋁進(jìn)行了除雜研究:鈦的去除在焙燒時進(jìn)行,通過添加氯化劑且在還原氣氛中焙燒鋁土礦可以除去鈦;用DDTC絡(luò)合沉淀法進(jìn)行除鐵,并研究其影響因素;硅的去除在硫酸溶出鋁土礦后的尾液中進(jìn)行,通過添加絮凝劑使硅酸自聚再分離開來;鈣、鎂的去除是利用其氟化物溶度積小的特點,采用NH4F為沉淀劑除去;用氨法將溶液中的鋁離子沉淀并分離開來,通過反復(fù)洗脫沉淀可使鈉鉀離子含量降到很低的水平,逐步去除雜質(zhì)后,產(chǎn)物中的雜質(zhì)含量均降到了0.05%以下,產(chǎn)物純度達(dá)到了99.91%。(4)以除雜后的鋁鹽為原料,制備了氧化鋁氣凝膠,研究了制取氣凝膠的工藝,并確定其工藝參數(shù),其工藝條件為:4g Al(NO_3)_3·9H_2O、乙醇40ml、水40ml、乙二醇2ml、環(huán)氧丙烷15ml。
[Abstract]:More than 98% bauxite in China belongs to diaspore type, which is very difficult to leach out. This is because the crystal form of diaspore type is very complete, the lattice energy is very large, and its chemical activity is very poor. Due to the rapid development of aluminum industry, the high quality bauxite resources in China are reduced, and the Al-Si ratio of most bauxite ores is 3 ~ 6. It is very difficult to meet the requirements of Bayer process for the treatment of bauxite, which seriously restricts the development of alumina industry in China. Using Bayer method to treat bauxite with low Al-Si ratio, the energy consumption is high, the process is complex and the cost is high. In this paper, the sulfuric acid method is used to treat the bauxite of medium and low grade, and the technological conditions of sulphuric acid leaching of bauxite are systematically studied, and on the basis of this, the metal impurity in the solution is removed. The alumina aerogel was prepared by using the product of removing impurity as the raw material and the preparation process was studied preliminarily. The impurity content of alumina aerogel was reduced to a very low level and the alumina aerogel was prepared from the product after impurity removal. The results are as follows: (1) the effects of pretreatment such as grinding and roasting on the dissolution of alumina were studied, and the mechanism of roasting bauxite was analyzed. The pretreatment conditions were as follows: bauxite size 100 渭 m, calcination temperature 650 鈩，

本文編號：2213850