本文選題：磷石膏 + 液相生長(zhǎng)法��； 參考：《西南科技大學(xué)》2017年碩士論文

【摘要】：近年來(lái),隨著磷化工企業(yè)的迅速發(fā)展,濕法磷酸工藝中不斷產(chǎn)生大量的固體廢棄物——磷石膏。由于磷石膏中含有多種雜質(zhì),露天堆放會(huì)導(dǎo)致嚴(yán)峻的環(huán)境問(wèn)題。利用磷石膏替代天然石膏制備硫酸鈣晶須,不僅彌補(bǔ)了天然石膏不可再生的缺陷,還為磷石膏應(yīng)用于附加值高、中高檔型材料方面開(kāi)拓了新領(lǐng)域。硫酸鈣晶須具有高模量、高強(qiáng)度、耐高溫、耐酸堿等特點(diǎn),是一種性能優(yōu)良的新型晶體材料。較高的性價(jià)比促使其具有較強(qiáng)的市場(chǎng)競(jìng)爭(zhēng)力和良好的應(yīng)用前景。本文主要研究磷石膏制備硫酸鈣晶須,探討了體系最佳反應(yīng)制度、雜質(zhì)對(duì)硫酸鈣晶須的影響和晶型助長(zhǎng)劑類型的選擇及最佳摻量的確定、硫酸鈣晶須的表面改性。以預(yù)處理后的磷石膏為原料,氯化鎂為晶型助長(zhǎng)劑,天然石膏作晶種,采用液相生長(zhǎng)法制備硫酸鈣晶須,分別考察了反應(yīng)溫度、反應(yīng)時(shí)間、料漿質(zhì)量分?jǐn)?shù)、晶種摻量、系統(tǒng)攪拌速度對(duì)晶須性能的影響。實(shí)驗(yàn)結(jié)果表明,最佳反應(yīng)制度工藝參數(shù):反應(yīng)溫度130℃,反應(yīng)時(shí)間4.0 h,料漿質(zhì)量分?jǐn)?shù)2.5%,晶種摻量9.0%,系統(tǒng)攪拌速度100 r/min。該條件下制備出的硫酸鈣晶須的平均長(zhǎng)徑比為112.65。由于磷石膏雜質(zhì)種類較多、成分復(fù)雜,本課題在最佳反應(yīng)制度研究的基礎(chǔ)上,通過(guò)外摻模擬法逐一研究了磷石膏中雜質(zhì)對(duì)硫酸鈣晶須的影響。實(shí)驗(yàn)結(jié)果表明,磷酸對(duì)硫酸鈣晶須具有明顯的抑制作用,隨著摻量的增加,晶須的長(zhǎng)度、長(zhǎng)徑比均減小。磷酸摻量4.4%時(shí),硫酸鈣晶須的平均長(zhǎng)徑比6.92。氫氟酸對(duì)硫酸鈣晶須長(zhǎng)度影響較小,但對(duì)直徑有顯著的粗化作用,導(dǎo)致晶須的長(zhǎng)徑比減小。氫氟酸摻量1.5%時(shí),硫酸鈣晶須的平均長(zhǎng)徑比7.71。有機(jī)物以物理吸附為主、化學(xué)吸附為輔相結(jié)合的方式吸附在晶須表面,從而抑制晶須的生長(zhǎng)。有機(jī)物摻量1.6%時(shí),硫酸鈣晶須的平均長(zhǎng)徑比17.64。晶型助長(zhǎng)劑對(duì)硫酸鈣晶須的生長(zhǎng)具有誘導(dǎo)、促進(jìn)作用。在最佳工藝制度的基礎(chǔ)上,分別研究鐵鹽、鎂鹽與十二烷基鹽的復(fù)配型助長(zhǎng)劑對(duì)硫酸鈣晶須性能的影響。實(shí)驗(yàn)結(jié)果表明,十二烷基鐵鹽復(fù)配型助長(zhǎng)劑對(duì)硫酸鈣晶須的促進(jìn)效果依次分別為:FX-3FX-2FX-5FX-6FX-4FX-1,其中FX-3型助長(zhǎng)劑對(duì)晶須生長(zhǎng)發(fā)育促進(jìn)效果最佳,此時(shí)晶須的平均長(zhǎng)徑比139.50。十二烷基鎂鹽復(fù)配型助長(zhǎng)劑對(duì)硫酸鈣晶須促進(jìn)效果依次分別為:MX-3MX-2MX-1MX-6MX-4MX-5,其中MX-3型助長(zhǎng)劑對(duì)晶須的生長(zhǎng)發(fā)育促進(jìn)效果最佳,此時(shí)晶須的平均長(zhǎng)徑比140.12。隨著FX-3型、MX-3型助長(zhǎng)劑摻量的增加,晶須長(zhǎng)度、長(zhǎng)徑比均先增加后減小。在反應(yīng)體系中,這兩種晶型助長(zhǎng)劑的最佳摻量分別均是1.0%。硅酸鈉作穩(wěn)定改性劑,對(duì)硫酸鈣晶須表面進(jìn)行改性處理。分別考察了改性劑用量、改性溫度、改性時(shí)間、烘干溫度對(duì)晶須表面的改性效果的影響。實(shí)驗(yàn)結(jié)果表明,最佳改性工藝參數(shù):穩(wěn)定改性劑量1.5%,改性溫度60℃,改性時(shí)間20 min,烘干溫度105℃(時(shí)間2 h)。該條件下改性硫酸鈣晶須的活化指數(shù)達(dá)到91%。
[Abstract]:In recent years, with the rapid development of phosphorous chemical enterprises, a large number of solid waste-phosphogypsum have been produced in the wet phosphoric acid process.Due to various impurities in phosphogypsum, open storage will lead to severe environmental problems.The preparation of calcium sulfate whisker by using phosphogypsum instead of natural gypsum not only makes up the defects of natural gypsum but also opens up a new field for the application of phosphogypsum in high added value and middle and high grade materials.Calcium sulfate whisker is a new crystal material with excellent properties, such as high modulus, high strength, high temperature resistance, acid and alkali resistance and so on.Higher performance-price ratio promotes its strong market competitiveness and good application prospects.In this paper, the preparation of calcium sulfate whisker from phosphogypsum was studied. The optimum reaction system, the influence of impurity on calcium sulfate whisker, the selection of crystal type promoter and the determination of optimum dosage, the surface modification of calcium sulfate whisker were discussed.Calcium sulfate whisker was prepared by liquid-phase growth method using phosphogypsum as raw material, magnesium chloride as crystal promoter and natural gypsum as crystal seed. The reaction temperature, reaction time, slurry mass fraction and seed content were investigated.The effect of stirring speed on whisker performance.The experimental results show that the optimum process parameters are as follows: reaction temperature 130 鈩，

本文編號(hào)：1738339