Analysis of Flocculation and Dewatering Mechanism and Influence Factors of Waste Slurry from Slurry TBM
In order to understand the solid-liquid separation performance of waste slurry from the slurry TBM(Tunnel Boring Machine)and improve the solid-liquid separation efficiency of the slurry,a chemical flocculation method was adopted to conduct an experimental study on the rapid slurry-water separation of waste slurry from construction works.The slurry flocculation sedimentation test,the particle gradation test,and the turbidity test were conducted under the influence of various kinds of PAM to investigate the influence of chemicals(APAM,NPAM,CPAM),molecular weights and dosage on the flocculation and sedimentation characteristics of the waste slurry.The test results indicated that APAM and NPAM have a significant effect on solid-liquidseparation of the waste slurry while CPAM has no obvious flocculation effect on the waste slurry;for APAM,when its molecular weight is 12 million,16 million,and 18 million,the dosages are 0.35g/L,0.3g/L and 0.25g/L respectively for the best flocculation effect;for NPAM,when its molecular weight is 12 million,16 million and 18 million,the dosages are 0.3g/L,0.3g/L and 0.25g/L respectively for the best flocculation effect.In the case of the optimal dosage,the sediment volume,sediment moisture content,and supernatant turbidity are the smallest,and the particle size D50 of the slurry is the largest;the mode of interaction between APAM and waste slurry particles is mainly"adsorption and bridging",and the mode of interaction between NPAM and waste slurry particles is mainly"electrical neutralization"and"adsorption and bridging".
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