磷石膏分解特性与其分段煅烧制备硫铝酸盐水泥研究
发布时间：2019-05-18 04:20
【摘要】：磷石膏是湿法生产磷酸过程中排放的工业废渣,随着磷石膏排放量逐年增加,解决其资源化利用问题迫在眉睫。利用磷石膏制备硫铝酸盐水泥是磷石膏资源化利用的一个重要途径,基于磷石膏部分分解制备硫铝酸盐水泥的思路,即磷石膏分解产生的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矿物,本文以提高磷石膏的分解率和促进其在某一温度段集中分解释放SO2气体为突破口,对磷石膏的分解特性与其分段煅烧制备硫铝酸盐水泥进行研究,以提高磷石膏在制备硫铝酸盐水泥时的利用率,达到大量消纳磷石膏的目的,对以磷石膏为主要组分制备硫铝酸盐水泥的后续研究具有重要参考价值。本文首先研究了磷石膏的高温分解特性,发现气氛、温度和C/S(磷石膏-活性炭体系中碳与硫的物质的量之比)对磷石膏分解率均存在一定的影响,在其他条件相同时,磷石膏在CO2气氛中的分解率高于N2和空气气氛中的分解率。与传统还原气氛不同的是,在CO2气氛中通过活性炭的掺入可形成弱还原气氛,有利于磷石膏的还原分解。重点采用低温弱还原-高温氧化气氛分段煅烧制度研究磷石膏的分解特性,结果表明,采用CO2-950℃-1h/空气-1200℃-1h的分段煅烧制度,可使C/S为2的磷石膏分解率达到87.69%,分解产物中不含CaS且未出现熔融,同时可控制SO2气体在900~1200℃的温度范围内集中释放,SO2气体理论浓度可达9.11%,达到收集制备硫酸的浓度要求。采用分段煅烧分解率达到87.69%的磷石膏配生料制备硫铝酸盐水泥,与原状磷石膏按传统硫铝酸盐水泥配料相比,可明显大幅度提高磷石膏的利用率;烧成的水泥熟料中除了有C4A3S?、C2S和C4AF外,还有中间过渡矿物C2AS,可能与预分解的磷石膏中P2O5等杂质的含量较高相关;烧制的硫铝酸盐水泥3d净浆抗压强度可达到40MPa以上,但其水化速率和强度低于天然石膏、磷石膏按传统配料烧制的硫铝酸盐水泥;早期水化产物以针棒状钙矾石和氢氧化铝凝胶为主,钙矾石与氢氧化铝凝胶相互交织,水泥浆体随着水化龄期的发展越来越致密。目前可初步表明,将磷石膏的分解与硫铝酸盐水泥熟料的烧成过程分开,采用分段煅烧预分解的磷石膏替代天然石膏并部分替代石灰石制备硫铝酸盐水泥是可行的。此外,利用原状磷石膏配生料,采用CO2-950℃-1h/空气-1270℃-1h的分段煅烧制度烧制硫铝酸盐水泥熟料以促进熟料烧成过程中磷石膏的分解,达到提高磷石膏利用率的目的。研究发现,磷石膏的分解程度会受到生料中其他组分以及生料形态的影响,目前分段煅烧熟料过程中磷石膏的分解率最高可达73.31%,与传统煅烧制度煅烧熟料过程中磷石膏的分解率相比已有明显的提高;磷石膏的实际分解率和配料时的预期分解率较为接近时,熟料矿物组成和预期基本一致。在前期研究中,利用磷石膏部分分解制备硫铝酸盐水泥时,其在替代天然石膏的同时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备硫铝酸盐水泥的可行性,理论分析计算表明,采用低硅含量的磷石膏制备硫铝酸盐水泥时,若合理调整煅烧制度使磷石膏分解率达到92%以上,即可实现部分分解的磷石膏完全替代石灰石和天然石膏,磷石膏在生料中掺量可提高至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，
本文编号：2479664
[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，
本文编号：2479664
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