本文選題：磷石膏 + 分解　； 參考：《昆明理工大學(xué)》2017年碩士論文

【摘要】：磷石膏是工業(yè)濕法磷酸工藝生產(chǎn)中產(chǎn)生的副產(chǎn)物,由于其產(chǎn)量大,綜合利用率低等問題嚴(yán)重影響磷酸工藝的發(fā)展和資源的浪費(fèi)。針對(duì)磷石膏循環(huán)利用的實(shí)際問題,在磷石膏制硫酸聯(lián)產(chǎn)水泥及流化實(shí)驗(yàn)過程中發(fā)現(xiàn)磷石膏粉末團(tuán)聚黏附現(xiàn)象較為嚴(yán)重,所以考慮到磷石膏熱分解過程的特性和反應(yīng)機(jī)理,本論文結(jié)合課題組前期研究,采用兩步法分解磷石膏,研究其過程反應(yīng)機(jī)理和團(tuán)聚黏附機(jī)理。進(jìn)行了對(duì)磷石膏流化態(tài)的熱態(tài)冷態(tài)黏附研究,以及SiO2對(duì)黏附團(tuán)聚的影響,通過對(duì)磷石膏脫硅進(jìn)而研究Si02對(duì)分解反應(yīng)的影響,并探索脫硅磷石膏對(duì)水泥熟料成分的研究。本論文得到的主要研究成果如下:1.通過對(duì)磷石膏做冷態(tài)流態(tài)化實(shí)驗(yàn),結(jié)果表明:常溫下,磷石膏混合粉體進(jìn)料量對(duì)于黏附量趨于穩(wěn)定值,隨著溫度的升高黏附量穩(wěn)定值有下降趨勢(shì);氣速越大,會(huì)明顯的降低顆粒的黏附程度,且隨著氣速增加,黏附程度趨于穩(wěn)定,在現(xiàn)有的實(shí)驗(yàn)條件下,風(fēng)速為2.2m/s時(shí)黏附量開始趨于穩(wěn)定;在相同溫度和通氣速率下,粉末顆粒粒徑越小越易黏附在壁面。2.磷石膏兩步法熱分解過程中黏附現(xiàn)象研究結(jié)果表明:在升溫過程中粉體的黏附程度呈先降低后有所增加再減小,且顆粒的團(tuán)聚現(xiàn)象和壁面黏附現(xiàn)象具有一定的一致性;在循環(huán)通氣階段,不同階段的黏附程度也不一樣,氧化階段壁面黏附程度會(huì)有明顯的下降,而當(dāng)切換到還原氣氛時(shí),顆粒的黏附程度又會(huì)加重;SEM分析管壁結(jié)垢物和管道流體物的形態(tài)發(fā)現(xiàn),結(jié)垢物形狀大小各異,粘結(jié)情況嚴(yán)重;而流體物中的顆粒整體形態(tài)較為規(guī)整,呈明顯的層狀,表面也比較平整。分析管壁結(jié)垢物和管道流體物XRF數(shù)據(jù)發(fā)現(xiàn)磷石膏在流化過程中Si、Al等礦物質(zhì)元素容易在壁面產(chǎn)生富集,并且增加壁面的黏附程度,而在循環(huán)通氣反應(yīng)過程中,CaO的產(chǎn)生會(huì)有效的破壞SiO2、Al2O3等產(chǎn)生的網(wǎng)狀結(jié)構(gòu),從而有效的降低顆粒的黏附現(xiàn)象;3.在對(duì)不同程度脫硅的磷石膏(含Si02量分別為8.8%、4%、2%)進(jìn)行黏附團(tuán)聚研究過程中發(fā)現(xiàn),Si02含量越低其團(tuán)聚黏附程度就越小,總體隨溫度變化趨勢(shì)基本一致。4.通過對(duì)不同程度脫硅的磷石膏(含Si02量分別為8.8%、4%、2%)進(jìn)行了熱分解對(duì)比和對(duì)水泥熟料指標(biāo)的評(píng)價(jià),結(jié)果表明:在熱重實(shí)驗(yàn)中,未脫硅磷石膏失重率明顯高于脫硅磷石膏,且Si02含量越低,在溫度950℃下還原反應(yīng)的反應(yīng)程度越低;通過循環(huán)兩步法分解磷石膏,未脫硅磷石膏、脫硅磷石膏(Si02量4%)和脫硅磷石膏(Si02量2%)的脫硫率分別為86.45%、75.15%和80.53%,說明一定量的去除Si02會(huì)一定程度抑制磷石膏的熱分解;通過對(duì)三種磷石膏分解產(chǎn)物分析后,脫硅磷石膏(Si02量2%)的三個(gè)率值更加符合水泥熟料規(guī)定,且脫硅磷石膏會(huì)明顯的降低硅率SM率值,增加石灰飽和系數(shù)KH,對(duì)于鋁率IM影響不明顯。
[Abstract]:Phosphogypsum is a by-product produced in the process of industrial wet phosphoric acid production. The development of phosphoric acid process and the waste of resources are seriously affected by its large output and low comprehensive utilization ratio. In view of the practical problems of phosphogypsum recycling, it is found that the agglomeration and adhesion of phosphogypsum powder is serious in the process of co-producing cement with sulfuric acid from phosphogypsum and fluidization, so the characteristics and reaction mechanism of phosphogypsum thermal decomposition process are considered. In this paper, the process reaction mechanism and agglomeration adhesion mechanism of phosphogypsum were studied by two-step decomposition of phosphogypsum. The hot and cold adhesion of phosphogypsum in fluidized state and the effect of SiO2 on adhesion and agglomeration were studied. The effect of Si02 on decomposition reaction was studied by desilication of phosphogypsum and the composition of cement clinker was studied. The main research results of this paper are as follows: 1. The cold fluidization experiment of phosphogypsum shows that the feed amount of phosphogypsum powder tends to be stable at room temperature, and decreases with the increase of temperature, and the gas velocity increases. The adhesion degree of particles decreased obviously with the increase of gas velocity, and the adhesion degree tended to be stable with the increase of gas velocity. Under the existing experimental conditions, the adhesion began to stabilize when the wind speed was 2.2m/s; at the same temperature and aeration rate, The smaller the particle size is, the easier it is to adhere to the wall. The results show that the adhesion degree of the powder decreases first and then increases and then decreases during the process of pyrolysis of phosphogypsum, and the agglomeration of particles is consistent with the phenomenon of wall adhesion to some extent. In the stage of circulatory ventilation, the adhesion degree of different stages is also different, the adhesion degree of wall surface in oxidation stage will decrease obviously, but when switching to reducing atmosphere, The adhesion degree of particles will aggravate the SEM analysis of the morphology of pipe wall fouling and pipe fluid. It is found that the shape of the fouling is different and the adhesion is serious, while the whole shape of the particles in the fluid is more regular and obviously layered. The surface is also relatively flat. By analyzing the XRF data of pipe wall fouling and pipe fluid, it is found that Si-Al and other mineral elements are easily enriched on the wall during fluidization, and the adhesion degree of the wall is increased. However, in the process of circulating ventilation reaction, the formation of Cao can effectively destroy the network structure produced by Sio _ 2O _ 2O _ 3, and thus effectively reduce the adhesion phenomenon of particles / Al _ 2O _ 3 / Al _ 2O _ 3 / Al _ 2O _ 3 / Al _ 2O _ 3 system. In the study of adhesion and agglomeration of phosphogypsum with different degree of desilication (containing Si02 content of 8.8% and 4%), it was found that the lower the content of SiO2 was, the smaller the degree of agglomeration adhesion was, and the overall trend of agglomeration was basically consistent with the change of temperature. The pyrolysis and comparison of phosphogypsum with different degree of desilication (including Si02 content of 8.8%) and evaluation of cement clinker index are carried out. The results show that the weight loss rate of undesilication phosphorous gypsum is obviously higher than that of desilication phosphorous gypsum in thermogravimetric experiment. The lower the content of Si02, the lower the degree of reduction at 950 鈩，

本文編號(hào)：1855858