【摘要】：磷石膏是濕法生產(chǎn)磷酸過程中排放的工業(yè)廢渣,隨著磷石膏排放量逐年增加,解決其資源化利用問題迫在眉睫。利用磷石膏制備硫鋁酸鹽水泥是磷石膏資源化利用的一個重要途徑,基于磷石膏部分分解制備硫鋁酸鹽水泥的思路,即磷石膏分解產(chǎn)生的CaO部分替代石灰石,未分解的磷石膏替代天然石膏形成水泥熟料礦物,本文以提高磷石膏的分解率和促進其在某一溫度段集中分解釋放SO2氣體為突破口,對磷石膏的分解特性與其分段煅燒制備硫鋁酸鹽水泥進行研究,以提高磷石膏在制備硫鋁酸鹽水泥時的利用率,達到大量消納磷石膏的目的,對以磷石膏為主要組分制備硫鋁酸鹽水泥的后續(xù)研究具有重要參考價值。本文首先研究了磷石膏的高溫分解特性,發(fā)現(xiàn)氣氛、溫度和C/S(磷石膏-活性炭體系中碳與硫的物質(zhì)的量之比)對磷石膏分解率均存在一定的影響,在其他條件相同時,磷石膏在CO2氣氛中的分解率高于N2和空氣氣氛中的分解率。與傳統(tǒng)還原氣氛不同的是,在CO2氣氛中通過活性炭的摻入可形成弱還原氣氛,有利于磷石膏的還原分解。重點采用低溫弱還原-高溫氧化氣氛分段煅燒制度研究磷石膏的分解特性,結(jié)果表明,采用CO2-950℃-1h/空氣-1200℃-1h的分段煅燒制度,可使C/S為2的磷石膏分解率達到87.69%,分解產(chǎn)物中不含CaS且未出現(xiàn)熔融,同時可控制SO2氣體在900~1200℃的溫度范圍內(nèi)集中釋放,SO2氣體理論濃度可達9.11%,達到收集制備硫酸的濃度要求。采用分段煅燒分解率達到87.69%的磷石膏配生料制備硫鋁酸鹽水泥,與原狀磷石膏按傳統(tǒng)硫鋁酸鹽水泥配料相比,可明顯大幅度提高磷石膏的利用率;燒成的水泥熟料中除了有C4A3S?、C2S和C4AF外,還有中間過渡礦物C2AS,可能與預分解的磷石膏中P2O5等雜質(zhì)的含量較高相關(guān);燒制的硫鋁酸鹽水泥3d凈漿抗壓強度可達到40MPa以上,但其水化速率和強度低于天然石膏、磷石膏按傳統(tǒng)配料燒制的硫鋁酸鹽水泥;早期水化產(chǎn)物以針棒狀鈣礬石和氫氧化鋁凝膠為主,鈣礬石與氫氧化鋁凝膠相互交織,水泥漿體隨著水化齡期的發(fā)展越來越致密。目前可初步表明,將磷石膏的分解與硫鋁酸鹽水泥熟料的燒成過程分開,采用分段煅燒預分解的磷石膏替代天然石膏并部分替代石灰石制備硫鋁酸鹽水泥是可行的。此外,利用原狀磷石膏配生料,采用CO2-950℃-1h/空氣-1270℃-1h的分段煅燒制度燒制硫鋁酸鹽水泥熟料以促進熟料燒成過程中磷石膏的分解,達到提高磷石膏利用率的目的。研究發(fā)現(xiàn),磷石膏的分解程度會受到生料中其他組分以及生料形態(tài)的影響,目前分段煅燒熟料過程中磷石膏的分解率最高可達73.31%,與傳統(tǒng)煅燒制度煅燒熟料過程中磷石膏的分解率相比已有明顯的提高;磷石膏的實際分解率和配料時的預期分解率較為接近時,熟料礦物組成和預期基本一致。在前期研究中,利用磷石膏部分分解制備硫鋁酸鹽水泥時,其在替代天然石膏的同時只能部分替代石灰石,本文分析了磷石膏完全替代石灰石和天然石膏制備硫鋁酸鹽水泥的可行性,理論分析計算表明,采用低硅含量的磷石膏制備硫鋁酸鹽水泥時,若合理調(diào)整煅燒制度使磷石膏分解率達到92%以上,即可實現(xiàn)部分分解的磷石膏完全替代石灰石和天然石膏,磷石膏在生料中摻量可提高至73%以上。
[Abstract]:The phosphogypsum is an industrial waste residue which is discharged in the process of producing phosphoric acid by a wet method, and as the emission of the phosphogypsum is increased year by year, the problem of resource utilization is solved. the method for preparing the sulphoaluminate cement by using the phosphogypsum is an important way of resource utilization of the phosphogypsum, The undecomposed phosphogypsum is used to replace the natural gypsum to form the cement clinker mineral, and the decomposition rate of the phosphogypsum is improved and the SO2 gas is released from the concentrated decomposition of a certain temperature section as a breakthrough, In order to improve the utilization rate of the phosphogypsum in the preparation of the sulphoaluminate cement, the purpose of a large amount of the phosphogypsum is achieved, and the follow-up research on the preparation of the sulphoaluminate cement with the phosphogypsum as the main component has important reference value. In this paper, the high-temperature decomposition of phosphogypsum is studied, and the atmosphere, temperature and C/ S (the ratio of the amount of carbon to sulfur in the phosphogypsum-activated carbon system) is found to have a certain effect on the decomposition rate of the phosphogypsum, and when the other conditions are the same, The decomposition rate of the phosphogypsum in the CO2 atmosphere is higher than the decomposition rate in the N2 and the air atmosphere. Unlike the traditional reduction atmosphere, a weakly reducing atmosphere can be formed by the incorporation of activated carbon in the CO2 atmosphere, which is beneficial to the reduction and decomposition of the phosphogypsum. The decomposition characteristics of phosphogypsum are studied by the low-temperature low-reduction-high-temperature oxidation atmosphere staged combustion system. The results show that the decomposition rate of the P-gypsum with C/ S 2 can reach 87.69% by using the staged combustion system of CO 2-950 鈩，

本文編號：2479664