本文選題：氟硅酸　切入點(diǎn)：氨化反應(yīng)　出處：《南昌大學(xué)》2016年碩士論文

【摘要】：氟硅酸是磷肥生產(chǎn)中的副產(chǎn)物,任其排放會(huì)污染環(huán)境,造成氟硅資源的浪費(fèi)。利用氟硅酸,將其轉(zhuǎn)化為高附加值的硅產(chǎn)品或氟產(chǎn)品有著良好的市場(chǎng)前景和環(huán)保意義。本實(shí)驗(yàn)以氟硅酸為原料,一步氨化反應(yīng)得到氟硅酸銨溶液,設(shè)計(jì)銨鹽鈣鹽除雜,得到凈化的氟硅酸銨溶液,經(jīng)過二步氨化反應(yīng)得到產(chǎn)品高純二氧化硅,然后高溫煅燒高純二氧化硅,制備了高純晶體石英。對(duì)反應(yīng)過程中的條件進(jìn)行了探索和優(yōu)化。制備氟硅酸銨溶液的最佳工藝條件為:一步氨化反應(yīng)終點(diǎn)p H=3.8~4.0,氨水滴加速度1.5ml·min~(-1),反應(yīng)溫度25℃,攪拌速度200r·min~(-1),在此優(yōu)化工藝條件下,氟硅酸銨得率93.6%。銨鹽為添加劑調(diào)節(jié)氟硅酸銨溶液p H=6.5,溶液中的Ca金屬雜質(zhì)去除率達(dá)88.8%,Mg金屬雜質(zhì)的去除率達(dá)81.2%;鈣鹽為沉淀劑除雜,溶液中Fe去除率為82.3%,Al去除率達(dá)79.8%。除雜的最佳工藝條件:m(鈣鹽):m(H2Si F6折100%計(jì))=9wt%,陳化40min,靜置9h,最佳工藝條件下,去除了溶液中97.9%的金屬雜質(zhì),得到了高純的氟硅酸銨溶液,除雜效果理想。當(dāng)m(鈣鹽):m(H2Si F6折100%計(jì))=9wt%時(shí),產(chǎn)品Si O_2中金屬雜質(zhì)去除率98.1%,雜質(zhì)含量小于100μg·g~(-1),屬于高純二氧化硅,產(chǎn)品Si O_2純度達(dá)到99.99%。制備高純二氧化硅的最佳工藝條件:反應(yīng)終點(diǎn)p H=8.5、反應(yīng)溫度40℃、氨水滴加速度4ml·min~(-1)。該條件下,高純二氧化硅得率94.6%,粒徑0.35μm。經(jīng)由IR、TG檢測(cè),證明產(chǎn)品是Si O_2,XRD分析,產(chǎn)品Si O_2為非晶態(tài);SEM分析,樣品分散性良好,呈蓬松多孔狀。高純二氧化硅在煅燒溫度高于1200℃時(shí)發(fā)生晶型轉(zhuǎn)化,當(dāng)溫度達(dá)到1300℃,保溫時(shí)間為2h時(shí),無定型Si O_2轉(zhuǎn)化為方石英晶體,轉(zhuǎn)化率接近100%;晶化后樣品的表面孔道消失,結(jié)構(gòu)更為緊實(shí);高溫煅燒后,樣品粒徑減小,體積收縮,當(dāng)煅燒溫度達(dá)到1300℃,體積收縮率達(dá)81.89%。
[Abstract]:Fluorosilicic acid is a byproduct of phosphate fertilizer production, which will pollute the environment and cause waste of fluorosilicon resources.It has good market prospect and environmental protection significance to convert fluorosilicic acid into high added value silicon or fluorine products.In this experiment, ammonium fluorosilicate solution was obtained by one step ammoniation reaction with fluorosilicic acid as raw material. Ammonium salt calcium salt was designed to remove impurities, and purified ammonium fluorosilicate solution was obtained.Then high-purity silica was calcined at high temperature to prepare high-purity crystal quartz.The conditions in the reaction process were explored and optimized.The optimum conditions for preparation of ammonium fluorosilicate solution are as follows: end point of one-step ammoniation reaction (pH 3.8C), ammonia droplet acceleration (1.5ml min-1), reaction temperature 25 鈩，

本文編號(hào)：1725469