本文選題：萃余酸　切入點(diǎn)：工業(yè)級磷酸一銨　出處：《武漢工程大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著能源成本的不斷上升,使用耗能更低的濕法磷酸代替熱法磷酸已經(jīng)成為一種趨勢。但是濕法磷酸含有很多的雜質(zhì),因此,目前世界上很多國家都在研究如何凈化濕法磷酸,而且溶劑萃取法是目前唯一工業(yè)化應(yīng)用的。溶劑萃取法凈化濕法磷酸不可避免的會(huì)產(chǎn)生副產(chǎn)物萃余酸,如何合理的利用凈化后產(chǎn)生的大量萃余酸便成為磷化企業(yè)發(fā)展的重點(diǎn)方向之一。利用萃余酸生產(chǎn)肥料磷銨的價(jià)值有限,用萃余酸生產(chǎn)工業(yè)級磷酸一銨可以更好的提高萃余酸的經(jīng)濟(jì)價(jià)值。本論文的主要研究內(nèi)容包括三個(gè)部分：首先是研究了萃余酸進(jìn)行氨化反應(yīng)時(shí)萃余酸中各個(gè)離子的沉淀情況并使用試劑磷酸模擬萃余酸進(jìn)行金屬離子摻雜實(shí)驗(yàn),研究金屬離子雜質(zhì)濃度對磷酸一銨產(chǎn)品質(zhì)量的影響。其次通過考察工業(yè)級磷酸一銨的溶解度及介穩(wěn)區(qū)寬度,晶體懸浮密度和過飽和度,估算磷酸一銨的結(jié)晶熱,對工業(yè)級磷酸一銨的結(jié)晶過程進(jìn)行了研究。最后優(yōu)化了以萃余酸為原料制備工業(yè)磷酸一銨的工藝,并考察不同因素對磷酸一銨品質(zhì)和收率的影響,得到最佳工藝條件。主要得出了以下結(jié)論：1.萃余酸氨化漿料中的MgO、Fe2O3、Al2O3、SO42雜質(zhì)的析出率隨pH增大而增大。Fe2O3、Al2O3在pH達(dá)到4的時(shí)候的析出率分別為99.73%和99.16%,MgO在pH4.5時(shí)析出率為91.24%,pH為5時(shí)析出率為98.12%。SO42-在pH為4.5時(shí)也有66.83%的析出率。萃余酸中含有Mg2+、Fe3+、Al3+這3種金屬雜質(zhì)都會(huì)影響所得的工業(yè)級磷酸一銨產(chǎn)品的品質(zhì),主要表現(xiàn)為降低其N含量。其中Mg2+雜質(zhì)含量最多,影響也最大,在用萃余酸生產(chǎn)工業(yè)級磷酸一銨時(shí)應(yīng)控制Mg2+含量少于3%。2.工業(yè)級磷酸一銨在水中的溶解度是溫度的函數(shù),隨著溫度的升高而升高,溶解度隨著溫度變化明顯,在工業(yè)提純或者生產(chǎn)時(shí),磷酸一銨的結(jié)晶可以用冷卻結(jié)晶來實(shí)現(xiàn)。在水溶液中,磷酸一銨介穩(wěn)區(qū)的寬度隨著溫度升高而逐漸變窄,35-60℃時(shí)的介穩(wěn)區(qū)寬度在10℃～15.7℃。晶體的收率隨著磷酸一銨結(jié)晶時(shí)間的增長而增大,但是到了40min以后晶體收率保持穩(wěn)定,結(jié)晶時(shí)間一般都控制在40min以內(nèi)即可。3.制備工業(yè)級磷酸一銨的最優(yōu)工藝為：稀釋比為1.75,第一次中和反應(yīng)終點(diǎn)pH為3.5,反應(yīng)溫度70℃,靜置時(shí)間為3.5h。第二次中和反應(yīng)終點(diǎn)pH為4.5,反應(yīng)溫度60℃,靜置時(shí)間為3h。濃縮的相對密度為1.37,結(jié)晶溫度40℃,結(jié)晶時(shí)間40min。在最優(yōu)的工藝下,磷酸一銨收率為32.32%,產(chǎn)品純度為98.79%,符合工業(yè)級磷酸一銨標(biāo)準(zhǔn)。
[Abstract]:With the increasing of energy cost, it has become a trend to replace thermal phosphoric acid with wet-process phosphoric acid with lower energy consumption. However, wet phosphoric acid contains a lot of impurities, so many countries in the world are studying how to purify wet-process phosphoric acid. Moreover, solvent extraction is the only industrial application at present. The purification of wet phosphoric acid by solvent extraction will inevitably produce the by-product leucic acid. How to make rational use of a large amount of extracted acid after purification has become one of the key directions in the development of phosphating enterprises, and the value of producing ammonium phosphate from fertilizer by extracting residual acid is limited. The economic value of industrial grade ammonium phosphate can be improved by the production of industrial ammonium phosphate. The main research contents of this thesis include three parts: firstly, we study each ion in the extraction residue acid when it is ammoniated. And the experiment of metal ion doping using reagent phosphoric acid to simulate the extraction of residual acid was carried out. The influence of metal ion impurity concentration on the quality of monoammonium phosphate product was studied. Secondly, the crystallization heat of ammonium phosphate was estimated by investigating the solubility, the width of metastable zone, the suspension density and supersaturation of crystal. The crystallization process of industrial grade monoammonium phosphate was studied. Finally, the process of preparing industrial ammonium phosphate from residual acid was optimized, and the effects of different factors on the quality and yield of ammonium monophosphate were investigated. The main conclusions are as follows: 1. The precipitation rate of MgO- Fe2O3Al2O3SO42 impurities in the ammoniated slurry is increased with the increase of pH value. The precipitation rate of Fe2O3Al2O3Al2O3 at pH 4 is 99.73% and 99.16mg-MgO in pH4.5 is 91.24g / h, respectively. The precipitation rate of Fe2O3Al _ 2O _ 3 is 99.73% and 99.16mg / Al _ 2O _ 3 / Al _ 2O _ 3 / Al _ 2O _ 3 / Al _ 2O _ 4 / Al _ 2O _ 3 / Al _ 2O _ 3 / Al _ 2O _ 4 slurry. The precipitation rate at 5:00 is 98.12%. So _ 42- there is also 66.83% precipitation rate at pH 4.5.The presence of Mg2 Fe _ 3O _ 3 Al _ 3 in the residual acid will affect the quality of the industrial grade ammonium phosphate. The main performance is to reduce its N content. The impurity content of Mg2 is the most, and the influence is also the biggest. The content of Mg2 should be controlled less than 3.2. the solubility of industrial grade ammonium phosphate in water is a function of temperature. With the increase of temperature, the solubility changes obviously. In industrial purification or production, the crystallization of monoammonium phosphate can be achieved by cooling crystallization. The width of the metastable zone of monoammonium phosphate becomes narrower and narrower at 35-60 鈩，

本文編號(hào)：1627558