Study On The Preparation Of Solidification Gelling Materials Of Typical Non-ferrous Metal Tailings And Their Green Wall Materials

Metal mineral resources are an important material basis for China’s social and economic development.However,a large number of tailings and goaf caused by of mineral resources mine not only waste a lot of land resources,but also damage the ecological environment seriously,and even cause safety accidents.Therefore,tailings cementing backfill goaf is one of the effective ways for its direct utilization,and it is also of great significance for the sustainable development of mineral resources and has become one of the research hotspots in recent years.In this paper,the composition of slag,cement,fly ash,volcanic ash and other main raw materials were optimized to prepare green cementing materials,which were respectively used to cure lead-zinc tailings and copper tailings respectively,and their curing properties were studied,and the curing mechanism was discussed and analyzed.The new cement-modified fly ash based cementing material was prepared by using cement as the main raw material,the fly ash as the auxiliary material,and the sulfate as the activator,and then used it to solidify the lead-zinc tailings.When the fly ash content was 8%,the mass ratio of cementing material to dry tailings(the mass ratio of fine and coarse tailings was 3:7)was 1:6,and the tailings slurry concentration was 70 wt%,the 3 d,7 d and 28 d compressive strength of the tailings solidified specimens was the highest,which was 1.31 MPa,1.69 MPa and 3.87 MPa respectively,and the softening coefficient was 0.92.Adding 0.1 wt% flocculant(PAM)could improve the strength of the specimen,but reduced the fluidity of slurry.The addition of 0.1 wt% flocculant(PAM)could increase the strength of specimens,but reduced the slurry fluidity.A new slag based cementing material(XB)was prepared by using S95 grade slag powder and volcanic ash as the main raw materials,cement and industrial alkali residue as the activator,and the copper tailings were solidified by it.When the mass ratio of XB cementing material to dry tailings was 1:8,the 3 d,7 d and 28 d compressive strength of the tailings solidified specimens was 1.56 MPa,2.46 MPa and 5.26 MPa respectively,and the softening coefficient of it was 0.85.When the amount of polycarboxylic acid water reducer was 1.0 wt%,the slurry fluidity of casting specimen was increased and the long-term strength of its harded specimen was increased by 10%,which could meet the requirements of mine filling standards.The tailings baking-free brick specimens were prepared by dry-press forming method,used copper tailing as the main material.When the mass ratio of cementing material(XB)to dry tailings was 1:10,the water consumption of the mixture was 12 wt%,and the molding pressure was 10 MPa,the 28 d compressive strength was 10.04 MPa.After 15 times of dry-wet cycle,the mass loss rate and strength loss rate of the specimen was 0.67% and 9.02% respectively.After 15 times of freeze-thaw cycle,the mass loss rate and strength loss rate of the specimen was 0.72% and 16.12% respectively.The baking-free brick had the better water resistance and frost resistance.