Research On The Properties Of Cemented Paste Backfill Of Fine Tailings

The paper took cemented paste backfill(CPB) prepared with iron ore fine tailings and lead-zinc ore overflow tailings as the research objects,and used the theoretical analysis 、 experimental research and microstructure analysis( X-ray diffraction、scanning electron microscopy analysis)to solve the high filling cost and low curing strength of fine tailings and the curing stability of fine tailings with high sulfur.The specific work carried out and the main results obtained were as follows:(1)The research of early-stage microstructure of CPB of iron ore fine tailingsFour types of samples were prepared: Portland cement slurry、complex binder slurry(75% Slag powder+15% Portland cement+5% Hydrated lime+5% Anhydrite)、and CPB mixed with the two binders. The hydrates and microstructures of CPB with different binders in early stages were compared using X-ray diffraction and electron microscopy.Shows that,compared with Portland cement,the complex binder is more suitable for CPB of iron ore fine tailings with high W/C ratio,more amorphous materials exist in final hydrates of complex binder,and hydrates of the complex binder in CPB are easy to disperse.(2)The influence of the fineness of two binders on consolidation of CPB of iron ore fine tailingsFixing the concentration of CPB slurry and changing the contents of Portland cement and complex binder(10%、5%),the consolidation of CPB prepared with binders with mechanical activation treatment and without treatment were compared.Shows that,whether Portland cement or complex binder, refining binders both can improve the compressive strength of CPB of iron ore tailings, especially the early-stage strength.The effect of mechanical activation treatment on complex binder is superior to Portland cement.(3) The influence of accelerators on consolidation of CPB of iron ore fine tailingsFixing the based mixture ratio of CPB slurry, the effects of alkali-accelerators(Ca O、Na OH、Na2O?1.5Si O2)and sulfate-accelerators(Na2SO4、Ca SO4、FGDgypsum)on the compressive strength of CPB were studied through single and double mixing methods.Shows that,all the accelerators can improve the cementation ability of slag complex binder(80% Slag powder+20% Portland cement)on tailings,and the optimal combination is Ca SO4 、 Na OH and aliphatic super plasticizer with the proportion of 5%:5%:0.8%(the percentage of the total binder):The 3d compressive srtength is increased by 73.50%,and the 28 d strength by 25.73%.The compressive strength of CPB is largely affected by FGD gypsum,which gradually increases with the increase of FGD gypsum contents in certain range,and the best addition is 15%(the percentage of the total binder) :The 3d compressive srtength is increased by74.61%,and the 28 d strength by 18.31%.(4)The consolidation and stability of CPB of lead-zinc ore overflow tailingsTo explore the impact of metakaolin and slag powder on the consolidation and stability of CPB of lead-zinc ore fine tailings,they were selected to replace a certain amount of Portland cement by equivalent with the fixed concentration of CPB slurry and total contents of binder.Shows that, in a fixed amount of total binder, the compressive strength of CPB has no change, but the late stability gradually increases with the increase of metakaolin replacement rates. However, slag powder can improve the compressive strength of solidified body,but the effect on the stability is not regular,obviously inferior to metakaolin.