磷石膏基建筑石膏的制备及改性研究

以磷石膏为原料，采用水洗法去除磷石膏中的杂质成分，通过低温煅烧制备建筑石膏，借助于TG-DSC技术研究煅烧温度、煅烧时间对石膏强度及三相组分含量的影响，然后考察缓凝剂三聚磷酸钠、增强剂粉煤灰、减水剂三聚氰胺及聚丙烯纤维等添加剂对石膏试块物化性能的影响。结果表明：在170℃、3 h低温煅烧条件下所制备的建筑石膏粉β-CaSO₄·0.5H₂O质量分数为72.23%，石膏试块力学性能优于GB/T 9776—2008《建筑石膏》中2.0级产品的要求；采用添加量为0.15%(质量分数，下同)的三聚磷酸钠作缓凝剂、添加量为5.00%的粉煤灰作增强剂、添加量为0.05%的三聚氰胺作减水剂及添加量为1.00%的聚丙烯纤维对建筑石膏粉改性处理，所制备的石膏试块7 d干抗折强度为4.17 MPa，干抗压强度为12.97 MPa。探讨了以磷石膏为原料制备建筑石膏粉中多种添加剂的作用，制备出具有良好性能的建筑石膏粉，为磷石膏综合利用提供技术方法和理论依据。     

磷石膏制备β-半水石膏粉实验研究

采用磷石膏制备β-半水石膏粉,对磷石膏粉煅烧温度、升温速度、煅烧时间、研磨条件、陈化时间等工艺条件进行了系统研究,获得了用磷石膏生产优等建筑石膏的工艺条件,为加快开发利用磷石膏资源奠定了基础.     

磷石膏煅烧改性制备自流平砂浆的研究

采用磷石膏煅烧改性成的无水磷石膏(AP)、α型高强石膏(α-HH)、石英砂、外加剂等为原料制备磷石膏基自流平砂浆,分析探讨了煅烧温度、α型高强石膏掺量、胶砂比以及外加剂掺量对样品凝结时间、力学强度等性能指标的影响.结果 表明:磷石膏经500℃煅烧后,28 d抗压强度为13.6 MPa;增大α型高强石膏掺量有利于提高无水磷石膏力学强度;减小胶砂比能改善砂浆流动性能.采用42％无水磷石膏、28％α型高强石膏、30％石英砂、0.01％ PE、0.2％ MSF及0.1％ HPMC配制的磷石膏基自流平砂浆,其性能指标满足JC/T 1023-2007《石膏基自流平砂浆》的要求.     

磷石膏生产β型石膏工艺流程的研究

针对硫酸法湿法磷酸生产副产的磷石膏,研究了用其生产β 型半水石膏粉的工艺流程.分析了目前常用的工业副产石膏生产工艺,结合磷石膏原料特性及试验数据,设计了球磨法处理磷石膏杂质+预干燥+流态化煅烧+冷却等整套工艺流程,并进行了产品质量及经济性预估,认为该工艺流程可减少原料中的有害杂质,提高产品质量和稳定性.     

磷石膏制备陶瓷模用β-半水石膏及其表征

以磷石膏为原料,制备了陶瓷模用β-半水石膏粉,利用XRF、XRD和SEM等手段研究了预处理和煅烧工艺对磷石膏及β-半水石膏的化学成分、物相和形貌的影响,并测试了β-半水石膏的物理性能。结果表明:以磷石膏为原料制备陶瓷模用β-半水石膏粉在工艺上是可行性的,其物理性能可以达到陶瓷模用β-半水石膏粉合格品的指标,以适量的三聚磷酸钠作为缓凝剂可以改善其凝结过快的不足。     

磷石膏制备β-半水建筑石膏技术研究

以磷石膏为原料,采用煅烧的方式制备β-半水建筑石膏粉,研究煅烧温度和煅烧时间对产品质量的影响。实验结果表明,最佳工艺条件为煅烧温度130℃、煅烧时间38 min,得到的β-半水建筑石膏粉中半水石膏、无水石膏、二水石膏质量分数分别为66.39%、11.23%、3.11%。     

磷石膏制备β型半水石膏粉的工艺参数研究

通过磷石膏制备β型半水石膏粉试验,研究了水洗、过筛、粉磨工艺,以及掺合料等因素对β型半水石膏粉基本性能的影响。试验结果表明,常规的水洗工艺对产品的基本性能影响不大;掺入适量的超细粉煤灰和石灰,可降低产品强度;采用原料预粉磨+煅烧的工艺能够有效提高产品强度,且产品性能可满足等级为3.0的建筑石膏标准的指标要求。     

我国磷石膏资源化利用现状及发展前景综述(续完)

4 磷石膏的工业应用 4．1磷石膏制建筑材料磷石膏可用于生产石膏粉，石膏粉有不同的类型、性质和用途，其主要类型是半水硫酸钙和无水硫酸钙。由半水硫酸钙和无水硫酸钙可生产各种石膏制品。     

简述磷石膏制备半水石膏的工艺及应用

简述磷石膏制备α-半水石膏和β-半水石膏的机制、生产工艺以及目前的应用领域。以磷石膏为原料制备β-半水石膏,能耗较高,产品强度低,缺乏市场竞争力。以磷石膏为原料制备的α-半水石膏制品更有发展前景,但磷石膏制备α-半水石膏影响因素较多,应根据磷石膏原料成分选择合适的生产方法。     

磷石膏煅烧工艺进展分析

磷石膏作为主要的工业副产石膏，通过煅烧制备得到建材石膏粉体。归纳了国内外现有磷石膏煅烧工艺特点及利弊，针对现有的炒锅、回转窑、沸腾炉、彼得磨、FC-沸腾炉、锤式粉碎等煅烧工艺存在的产品质量不稳定、可控性差、功能单一、能耗高、投资高等技术及装备问题，提出流化床煅烧工艺。重点介绍了流化床煅烧磷石膏工艺技术具有大型化、流态化、产品多元化、干法净化、绿色环保的特点及技术创新优势。并与目前主流煅烧工艺产品性能指标分析进行对比，得出流化床煅烧磷石膏工艺产品质量稳定性好、可控性强、性能指标优越，必然成为未来磷石膏制备建材石膏粉体的主流技术手段，为中国磷石膏的煅烧资源化利用提供指导价值。     

磷石膏生产粉刷石膏的加工工艺研究

本文在实验的基础上对磷石膏生产粉刷石膏的加工工艺进行了研究，提出了磷石膏加工工艺设计原则，优化了其配比和工艺条件。使用单掺无机矿物保水剂制备的粉刷石膏性能优于甲基纤维素保水剂，为粉刷石膏的研制提供了理论基础。     

Microstructure of hardened gypsum pastes

Specific surface areas and pore size distribution analysis were taken as essential parameters to explore the microstructure of hardened gypsum pastes. The hydration of gypsum plaster is essentially affected by the water/plaster ratio of the mix, and by the presence of additives which might act as retarders or accelerators to the hydration process. Affecting the microstructure would mutually lead to variations of the compressive strength of the hardened pastes, and these variations are also discussed. Results are mainly expressed in terms of the solid (measured by the extent of its specific area) to the space (pore) ratios. Dual distribution of pore sizes was observed and the two groups of pores are designed as S (small) and L (large) pores. Similarities to the microstructure of hardened Portland cement pastes are indicated. Accelerators appear to function differently from retarders, and the effects of water/plaster ratios were investigated in both cases. The results obtained may carry many significant practical implications to the future use of hardened gypsum pastes.     

石膏矿渣绿色材料的研究进展

对工业副产石膏的产量和危害做了介绍,采用新型石膏矿渣绿色环保材料可实现石膏的资源化循环利用。利用矿物和试剂充分改善石膏复合材料的强度和耐水性能,可提高其稳定性,使石膏矿渣绿色材料在保温材料、混凝土、免烧砖和粉刷石膏中得到有效利用,加快可持续的绿色生态文明建设,并对今后的研究方向做了展望。     

α半水脱硫石膏流动度经时性及减水剂适用性

研究了α半水脱硫石膏流动度经时性及其影响因素,对掺减水剂石膏流动度经时性与流动度经时损失的内在原因进行了分析。α半水脱硫石膏流动度经时损失大,水化6 min流动度损失20%以上,α半水脱硫石膏快速水化对游离水消耗与束缚,以及双电层结构破坏,ξ电位迅速降低是导致流动度经时损失的内在原因。萘系减水剂(FDN)的分散作用主要依赖ξ电位的静电斥力,其分散稳定性差,流动度经时损失大;聚羧酸减水剂(PC)主要依靠空间位阻发挥分散作用,其分散稳定性较好,流动度经时性损失较小。高效减水剂应具备空间位阻效应,复配缓凝剂是抑制α半水脱硫石膏流动度经时损失的有效方法。     

聚醚聚酯磺酸钠结构对β-半水石膏性能的影响

通过分子结构设计并合成了三种聚醚聚酯磺酸钠(PSVA、PSPA和PSMPA)大分子,研究分子结构对β-半水石膏性能的影响.结果表明,PSVA、PSPA和PSMPA均可改善石膏的机械强度,其能力依序为:PSVA>PSMPA>PSPA;聚醚聚酯磺酸钠促进β-半水石膏的初凝能力与其改善石膏机械强度呈负相关,延缓β-半水石膏终凝、提高稠度和改善石膏吸水性能力均与大分子支链化程度呈正相关;相比大分子亲水性,孔隙率对石膏吸水性的影响更大,且石膏的吸水性与孔隙率呈正相关.     

By-product gypsum from the tapioca starch process

By-product gypsum derived from the tapioca starch process was calcined in the laboratory and evaluated for use in the manufacture of plaster of Paris and plaster products. The gypsum had a purity of about 98%, was fine (1 %, + 150μm) and had a low bulk density (600 kg/m³). The laboratory calcined material had a higher than normal water requirement of 120–130 ml/100 g, and a long setting time of 65 min. Specimens cast at a water/solids ratio of 1·0 had a low compressive strength of 2·4–3·4 MPa. However, the mechanical strength could be improved by the addition of water-reducing admixtures, and a strength of 7·6 MPa was obtained at a water/solids ratio of 0·6 and a resulting density of 1190 kg/m³. The waste gypsum derived from the manufacture of tapioca starch appears to be suitable for the manufacture of plaster of Paris and plaster products after the incorporation of water-reducing admixtures into the plaster slurry.     

Effect of phosphatic and fluoride impurities of phosphogypsum on the properties of selenite plaster

The effect of phosphatic and fluoride impurities present in waste phosphogypsum on the setting time, strength development and morphology of selenite gypsum plaster have been studied. The results showed that soluble phosphates retard the setting and strength development of plaster while soluble fluorides decrease the setting time and reduce the density and strength. The gypsum crystals in the set plaster are modified from to euhedral to subhedral prismatic, rhombic, tabular and lath-shaped crystals of variable sizes interspersed with subhedral to anhedral needles. It is concluded that the formation of prismatic, rhombic and lathelike crystals retards the normal setting and strength development of selenite gypsum plaster.     

High porosity (> 90%) cementitious foams

High porosity foams based on Portland limestone cement or gypsum plaster were prepared by a simple method of stirring and drying using low levels of the food additives: methyl cellulose and iota carageenan gum. Thermal conductivity of 0.11 W m^− 1 K^− 1 at 92% porosity was achieved but compressive strength was also very low. Foams were almost closed cell. Attempts to improve strength by incorporation of short staple glass fibre were only partially successful because of a change in the failure mode from progressive collapse to uniform fibre-cement debonding facilitated by the ability of the fibre network to transmit stress throughout the assembly. This approach to fire resistant insulation materials does not yet match the high strength/conductivity ratios of calcium silicate products but deserves exploring because of the simplicity of preparation and the compositional freedom for using mixtures of hydraulic cement and other powders.     

用化学石膏配制自流平材料的研究

采用煅烧法和蒸压法对化学石膏进行处理,研究了处理温度和外加剂对石膏性能的影响.通过2*6析因实验方法对掺加石膏、水泥、木质素纤维、消泡剂和可再分散胶粉对石膏基自流平材料的性能影响进行了研究,另外还研究了不同晶形转化剂对自流平材料性能的影响.     

可溶无水石膏Ⅲ对半水石膏水化过程的影响

研究了可溶无水石膏Ⅲ(AⅢ)对半水石膏水化过程的影响。采用常规分析方法、XRD和扫描电镜对半水石膏原料、水化过程和石膏产品进行分析和表征。结果表明:新粉AⅢ活性高,水化速度快,导致添加减水剂时几乎未见减水增强效果。陈化粉添加加速剂YT,当添加量在0.1%~0.2%时,石膏制品2h的强度增加22%,24 h的强度增加20%~30%;添加FDN减水剂,当掺量在0.2%时,水膏比从0.7 m L/g降低至0.6 m L/g(降低了14.2%),减水效果明显。