磷石膏改良疏浚泥试验研究

Experimental Research on Dredged Sludge Amelioration by Phosphogypsum

通过添加生石灰可以改良疏浚泥的物理力学性质,实现资源化利用。但是单独采用生石灰改良疏浚泥处理成本较高,而且会产生高碱性问题。通过添加磷石膏以达到减少生石灰用量,提高处理效果,降低碱性的目的。采用了击实试验、直剪试验以及酸碱测试试验研究了添加磷石膏后改良疏浚泥的密实性、抗剪强度以及pH值的变化规律。研究结果表明,添加的磷石膏与氢氧化钙反应生成的钙矾石能够充填疏浚泥中的孔隙,提高土体的密实性;当磷石膏在一定添加比例条件下,能够提高粘聚力和内摩擦角,但是过多的添加量也会造成粘聚力下降;磷石膏能够降低改良疏浚泥的碱性,但是需要达到一定的比例才具有较为显著的效果。

The dredged sludge could be reused and its characteristic of mechanics can be improved by lump lime, but the problems of high cost and high alkalinity may be produced by using lump lime lonely. The above problems could be solved by using phosphogypsum. The experiments of compaction, straight shear and acid-base detection were carried out to study the compactness, shear strength and pH value of the improved dredged sludge. The experimental results show that the ettringite brought from the reaction of phosphogypsum and calcium hydroxide could fill the pore and improve the dense. The value of c and ~ could be improved under the reasonable quantity of additive. If the phosphogypsum is added more than the reasonable quantity, the value of c would be fallen. The value of pH could be declined when the phospho- gypsum quantity is reasonable.