本文關鍵詞： 高鈣配方 還原率 殘渣活性 二步法 爐襯隔熱材料　出處：《西南科技大學》2015年碩士論文　論文類型：學位論文

【摘要】：近年來,我國的磷肥生產已不能滿足農業(yè)需求,尋求一種直接高效地利用中低品位磷礦生產磷酸的方法是目前急需解決的難題。窯法磷酸是一種直接還原磷礦生產磷酸的方法,但應用于工業(yè)生產還存在很多問題,如對窯爐設備要求高、生產工藝尚不成熟、殘渣排放量大等。我國科研設計單位正在研究窯法磷酸的生產工藝特點及相應設備結構,以期將窯法磷酸盡快應用于工業(yè)生產。本課題采用了窯法磷酸生產中的高鈣配方來還原中低品位磷礦,添加磷石膏為礦化劑,通過對配料進行熱重差熱分析確定最佳還原溫度。研究了鈣硅比、氮氣通入速率、炭過剩系數(shù)、保溫時間、料球直徑、還原溫度等因素對磷礦還原率的影響,從而確定了磷礦還原的最佳工藝條件,并在此基礎上對殘渣做了活性測試,結果表明殘渣可代替粉煤灰做礦物摻和料使用。研究結果如下:磷礦的還原率隨鈣硅比的增加而增大,隨氮氣過剩系數(shù)的增加呈先減小后增加的趨勢,當?shù)獨馔ㄈ胨俾蕿? 0 0 m l/m i n,還原率最大。炭過剩系數(shù)從1.1到1.4還原率增大很明顯,炭過剩系數(shù)在1.4以后還原率增加不明顯;磷礦的還原率均是隨著球直徑減小和保溫時間的延長而增大,但影響很小,有利于工業(yè)生產。本實驗探索的最佳還原工藝為:Ca/Si=2,氮氣通量為700ml/min,炭過剩系數(shù)為1.4,還原溫度1250℃,保溫時間210min,得到的磷礦還原率均在94.0%以上。在最佳工藝參數(shù)下,殘渣出現(xiàn)水化性能好的膠凝產物C2S,且殘渣以粉煤灰標準測試的7、28天活性指數(shù)達6 8.1%、8 3.0%,可以代替粉煤灰做水泥生產的礦物摻合料使用。窯法磷酸生產中需保證還原氣氛,且殘渣需急冷保證活性,還會逸出氟化鈉、氟化鉀等堿性物質,要求爐襯材料具有在還原氣氛、堿性氣氛中穩(wěn)定性好,抗熱震穩(wěn)定性好等性能。本實驗利用二步法工藝低溫制備出了一種能用于窯法磷酸生產的窯爐內襯隔熱材料六鋁酸鈣-鎂鋁尖晶石復相陶瓷。結果如下:配料經200℃水熱處理、1 4 5 0℃保溫3 h可制備出六鋁酸鈣-鎂鋁尖晶石復相材料。復相材料氣孔率高達72.2%,孔徑分布范圍窄為700nm-1.2μm,陶瓷片抗壓強度高達142.7MPa,是一種新型的優(yōu)質窯爐用隔熱耐火材料。六鋁酸鈣-鎂鋁尖晶石復相陶瓷的氣孔率、抗壓強度隨著水熱溫度的升高而增加,隨著水熱溫度的升高,孔徑尺寸向大孔方向移動,六鋁酸鈣的形貌也由堆疊片狀變?yōu)榻徊婢鶆蚍植嫉谋∑瑺�。六鋁酸鈣形貌受氫氧化鋁形貌控制,當氫氧化鋁為板狀三水鋁石時,六鋁酸鈣為堆疊片狀形貌,當氫氧化鋁為三維插片薄水鋁石時,六鋁酸鈣交叉分布的薄片狀。
[Abstract]:In recent years, the production of phosphate fertilizer in China has not been able to meet the demand of agriculture. It is an urgent problem to find a direct and efficient way to produce phosphoric acid from medium and low grade phosphate rock. Kiln phosphoric acid is a method of direct reduction of phosphate rock to produce phosphoric acid. However, there are still many problems in application in industrial production, such as high requirement for kiln equipment, immature production process and large amount of residue discharge. Our country's scientific research and design units are studying the characteristics of kiln phosphoric acid production process and the corresponding equipment structure. In order to apply kiln phosphoric acid to industrial production as soon as possible, the high calcium formula of kiln phosphoric acid production was used to reduce the medium and low grade phosphate rock, and phosphogypsum was added as mineralizer. The optimum reduction temperature was determined by thermogravimetric differential thermal analysis (TG-DTA). The effects of Ca / Si ratio, nitrogen flux rate, carbon excess coefficient, holding time, ball diameter and reduction temperature on the reduction rate of phosphate rock were studied. The optimum technological conditions for the reduction of phosphate rock were determined, and the activity of the residue was tested on this basis. The results show that the residue can be used as mineral admixture instead of fly ash. The results are as follows: the reduction rate of phosphate rock increases with the increase of the ratio of calcium to silicon, and decreases first and then increases with the increase of excess coefficient of nitrogen. When the nitrogen flux rate is 7 000 ml / ml, the reduction rate is the highest. The reduction rate of carbon excess coefficient increases obviously from 1.1 to 1.4, but the reduction rate does not increase obviously when the carbon excess coefficient is 1.4. The reduction rate of phosphate rock increases with the decrease of the diameter of the ball and the prolongation of the holding time, but the effect is very small, which is beneficial to the industrial production. The optimum reduction process explored in this experiment is: the ratio of nitrogen flux is 700ml / min, the carbon excess coefficient is 1.4, and the reduction temperature is 1250 鈩，

本文編號：1551516