脱除磷石膏中水溶磷、水溶氟的实验研究

磷石膏的综合利用对磷化工行业可持续发展和长江流域生态保护具有重大意义。但是磷石膏中含有少量磷、氟以及有机物等有害杂质影响其应用性能,不能直接利用。因此,通过采用石灰中和、水洗、浮选3种净化除杂预处理工艺研究了云南安宁某公司磷石膏中水溶磷、水溶氟的脱除规律。结果表明,石膏调浆-石灰-母液循环预处理技术能有效脱除磷石膏中的水溶磷、水溶氟,脱除率分别为74.95%、76.20%,质量分数可降至0.090%、0.043%,满足GB/T 23456—2018《磷石膏》的二级品指标限值要求;三级逆流水洗工艺也能有效脱除磷石膏中的水溶磷、水溶氟,脱除率分别为78.81%、89.94%,质量分数可降至0.087%、0.018%,预处理后的磷石膏质量也可达到GB/T 23456—2018《磷石膏》的二级品指标要求;而“一粗二精”正浮选工艺不仅能实现石膏和石英的高效分离,而且也能实现水溶磷、水溶氟的有效脱除,从而提高了产品纯度,并且达到GB/T 23456—2018《磷石膏》的一级品指标要求。从经济可行性角度和当前磷石膏的低值化利用途径分析,研究形成的石膏调浆-石灰-母液循环磷石膏预处理工艺更具有适用性。

Experimental study on removal of water-soluble phosphorus and water-soluble fluorine from phosphogypsum

The comprehensive utilization of phosphogypsum is of great significance to the sustainable development of phosphor-chemical enterprise and the eco-environmental protection of the Yangtze River Valley.However,the phosphogypsum contains a small amount of phosphorus,fluorine,organic compounds,and so on.The harmful impurities impact its application performance,which can′t be used directly.So,the distribution and removal of water-soluble phosphorus and water-soluble fluorine in phosphogypsum from a company in Anning were studied by lime neutralization,water washing and flotation.The results showed that the water-soluble phosphorus and water-soluble fluorine in phosphogypsum could be removed effectively by gypsum mixing,adding lime and mother solution cyclic utilization technique.The removal rates of them were 74.95% and 76.20% respectively,and their contents were 0.090% and 0.043% separately,which could meet the limit requirements of secondary indicators in GB/T 23456—2018《phosphogypsum》 standard.The water-soluble phosphorus and water-soluble fluorine could also be removed effectively by the three-stage countercurrent washing process.The removal rates of them were 78.81% and 89.94% respectively,and their contents were 0.087% and 0.018% separately.The quality of the pretreated phosphogypsum also could meet the secondary grade index requirements of GB/T 23456—2018《phosphogypsum》 standard.The efficiency separation of CaSO₄·2H₂O and SiO₂ was successfully achieved by the direct flotation process of one-stage roughing and two-stage cleaning.Simultaneously,the water-soluble phosphorus and the water-soluble fluorine in phosphogypsum were also effectively removed.Thus the quality of phosphogypsum was improved and reached the first-grade index requirements of GB/T 23456—2018《phosphogypsum》.From the perspective of economic feasibility and the analysis of the current low value utilization of phosphogypsum,the gypsum slurry mixing lime mother liquor circulating phosphogypsum pretreatment process formed by research is more applicable.