【摘要】：生石膏是我國儲量豐富的天然礦藏,電廠脫硫石膏是目前大量存在的工業(yè)副產(chǎn)品,目前由于工藝技術(shù)限制,市場上對二者的應用僅限于建筑行業(yè)等領域。由于生石膏和電廠脫硫石膏主要成分都是二水硫酸鈣,因此,本文研究了以生石膏和電廠脫硫石膏為原料,采用常壓酸化法制備無水硫酸鈣晶須工藝,對我國石膏資源的開發(fā)、脫硫石膏的循環(huán)利用以及硫酸鈣晶須的制備研究有重要的實際意義。 常壓酸化法制備硫酸鈣晶須首先要選擇合適的溶劑提高硫酸鈣在溶液中的溶解度,以提高料漿濃度,增大硫酸鈣晶須產(chǎn)率。本文采用容量法測定生石膏溶解度,試驗研究了生石膏在多種溶液中的溶解性能,結(jié)果表明：生石膏在強電解質(zhì)、銨鹽溶液及鹽酸溶液中的溶解度差異較大,并且受酸度、鹽溶液濃度影響。相比較而言,生石膏在濃度為30%-40%的檸檬酸銨溶液中的溶解度最大,為4.41g/100ml。在鹽酸濃度為10%、氯化鎂、氯化鈉濃度均為5%的混合溶液中的溶解度可達2.04g/100ml。上述研究結(jié)果對常壓酸化法制備硫酸鈣晶須工藝的開發(fā)具有指導意義。 常壓酸化法制備無水硫酸鈣晶須是目前晶須制備領域的重要研究課題,本試驗研究了常壓酸化法制備無水硫酸鈣晶須的工藝流程及其各種影響因素,并通過熱重分析、XRD、三維數(shù)字顯微鏡、SEM等手段對硫酸鈣晶須產(chǎn)品進行表征。實驗詳細研究了不同影響因素對硫酸鈣晶須產(chǎn)品形貌、組成及長徑比的影響,包括反應時間、料漿濃度、溶液中硫酸根離子與鈣離子摩爾比、晶須助長劑類型及添加量、冷卻時間等,并確定最佳制備工藝,結(jié)果表明：以生石膏和電廣脫硫石膏為原料、氯化鎂為晶型助長劑,采用常壓酸化法制備無水硫酸鈣晶須的最佳工藝條件為：Ca2+濃度0.15mol/L,硫酸根離子與鈣離子摩爾比10,沸騰時間15min,陳化時間6小時,晶型助長劑鈣鎂摩爾比13,產(chǎn)品在200℃下脫水0.5h。 本文從硫酸鈣晶須的制備機理和生長機制方面闡述了硫酸鈣晶須制備的主要機理和微觀生長過程,并介紹了硫酸鈣晶須生長的不同階段的相變化和生長規(guī)律。提出了硫酸鈣晶須生長過程的固液生長機理和位錯生長體制,最后對硫酸鈣晶須研究的發(fā)展方向進行了展望。
[Abstract]:Raw gypsum is a rich natural mineral deposit in our country. Desulfurization gypsum in power plant is a large number of industrial by-products at present. At present, due to the technical limitation, the application of both in the market is limited to the construction industry and other fields. Since the main components of raw gypsum and desulphurized gypsum in power plant are calcium sulfate dihydrate, this paper studies the preparation of anhydrous calcium sulfate whisker from raw gypsum and desulfurized gypsum in power plant by atmospheric pressure acidizing method, and the development of gypsum resources in China. The recycling of desulphurized gypsum and the preparation of calcium sulfate whisker have important practical significance. To prepare calcium sulfate whisker by acidizing under atmospheric pressure, the solubility of calcium sulfate in solution should be improved by selecting suitable solvent to increase the slurry concentration and increase the yield of calcium sulfate whisker. In this paper, the solubility of gypsum was determined by volumetric method. The solubility of gypsum in various solutions was studied. The results showed that the solubility of gypsum in strong electrolyte, ammonium salt solution and hydrochloric acid solution was quite different, and its acidity was also studied. The concentration of salt solution affected. In contrast, the solubility of gypsum in ammonium citrate solution with concentration of 30% to 40% was the highest, which was 4.41 g / 100 ml. When the concentration of HCl is 10 and the concentration of magnesium chloride and sodium chloride is 5%, the solubility can reach 2.04g / 100ml. The results are of great significance for the development of calcium sulfate whisker preparation by acidizing under atmospheric pressure. The preparation of anhydrous calcium sulfate whisker by atmospheric pressure acidizing method is an important research topic in the field of whisker preparation at present. The technological process of preparing anhydrous calcium sulfate whisker by atmospheric pressure acidification method and its various influencing factors have been studied in this experiment. The products of calcium sulfate whisker were characterized by thermogravimetric analysis (TGA) and three dimensional digital microscope (SEM). The effects of different factors on the morphology, composition and aspect ratio of calcium sulfate whisker were studied in detail, including reaction time, slurry concentration, molar ratio of sulfate ion to calcium ion, type and amount of whisker promoter. The results showed that raw gypsum and electrodesulfurized gypsum were used as raw materials and magnesium chloride as crystal promoter. The optimum conditions for the preparation of anhydrous calcium sulfate whiskers by atmospheric pressure acidification are as follows: the concentration of Ca 2 2 is 0.15 mol / L, the molar ratio of sulfate ion to calcium ion is 10, boiling time is 15 min, aging time is 6 hours, the molar ratio of calcium to magnesium is 13, and the product dehydrates at 200 鈩，

本文編號：2259302