Abstract
This experiment studied the influence law of the strength of CPB affected by tailings content, Gobi aggregate content, cement content, and slurry concentration. The results show, for the CPB with concentration of 77%, when the addition amount of cement reaches 20%, the addition amounts of tailings and Gobi aggregate change within the ranges of 12∼24% and 56∼68%, respectively. The strength of CPB has been gradually improved when the addition amount of Gobi aggregates decreases and the addition amount of tailings increases. In this case, the slump of CPB changes within the range of 26.5 cm∼26.9 cm while the strength of CPB changes within the range of 4.021∼6.845 MPa. Considering future utilization value of tailings, the addition amount is finally set at 16% in production, and the addition amount of Gobi aggregate is set at 64%; namely, tailings: Gobi aggregate = 20 : 80. When the addition amount of cement is 20% (cement/(tailings + Gobi aggregates) = 1 : 4), the strength of CPB reaches 5.62 MPa which meets the production requirement. When the heading machine is used for tunnelling mine roadway in bottom backfill of VCR stope, no collapse or delamination occurs without support, showing good stability and integrity of backfill. When the adjacent stope ore is mined, the backfill with cement content of 11.1%, 14.3%, 20%, and 25% is exposed. In the process of mining, no collapse or delamination occurs. Therefore, the proportion of various backfill materials applied in production is reasonable, being verified by the experiment and field test.
Highlights
Over the course of past 20 to 30 years, the China mining has gradually developed tending to stricter and perfect ecoenvironment protection
Based on the slump test, it is known the slump of the above four types of paste backfill slurry changes from 26.9 cm to 26.5 cm with increasing of tailings and decreasing of Gobi aggregates. is means that the more the tailings added, the more the water that can be absorbed by the paste to reduce the slump of backfill slurry
If there are more tailings particles with the percentage content of tailings reaching 20% and 24%, the particles of Gobi aggregates will be more tightly encapsulated. erefore, macroscopically, this shows that y = 3.8482ln (x) – 5.3941
Summary
Over the course of past 20 to 30 years, the China mining has gradually developed tending to stricter and perfect ecoenvironment protection. In recent 10 years, some provinces have introduced corresponding environmental protection policies and regulations in succession, requiring the mining enterprises to have sound tailing disposal systems and preventing the land from collapse. Among the tailing disposal methods, the best way is to use tailings as filling material in the underground goaf so as to achieve objectives such as maximum use of tailings, safety and environmental protection of mine, ground pressure controlling, and resource recycling as well as maintaining the sustainable development. In backfilling of underground goaf, a lot of tailings from ore-dressing can be used; in this process, tailing discharge is reduced and the pollution
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