磷石膏基建筑石膏的制备及改性研究

Study on preparation and modification of phosphogypsum-based architectural gypsum

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-CaSO_(4)·0.5H_(2)O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。

Using phosphogypsum as raw material,the impurities in phosphogypsum were removed by water washing method,architectural gypsum was prepared by low-temperature calcination,and the effects of calcination temperature and calcination time on gypsum strength and three-phase component content were studied with the help of DSC-TG technology,and then the effects of additives such as sodium tripolyphosphate,fly ash reinforcing agent,melamine and polypropylene fiber of retarder were investigated on the physical and chemical properties of gypsum test block.The results showed that the mass fraction ofβ-CaSO_(4)·0.5H_(2)O prepared under the condition of low calcination at 170℃and 3 h was 72.23%,and the mechanical properties of gypsum test block were better than those of grade 2.0 products in GB/T 9776—2008“Building Gypsum”The sodium tripolyphosphate with an added amount of 0.15%(mass fraction,the same below)was used as a retarder,and fly ash with an added amount of 5.00%was used as a reinforcing agent with an addition amount of 0.05%melamine was used as a water reducing agent and polypropylene fiber with an addition of 1.00%was modified to build gypsum powder,and the dry flexural strength and dry compressive strength of the prepared gypsum test block were 4.17 MPa and 12.97 MPa for 7 d.The role of various additives in the preparation of architectural gypsum powder using phosphogypsum as raw material was discussed,and the construction gypsum powder with good performance was prepared,which provided technical methods and theoretical basis for the comprehensive utilization of phosphogypsum.