Full
Outline
In order to solve the problem of low comprehensive utilization rate of circulating fluidized bed fly ash (CFBFA), coal mine backfill materials were prepared by adding a small amount of cement with CFBFA as the main raw material. The differences in physical and chemical properties between CFBFA and fly ash were compared. On this basis, the control variable method was used to explore the effects of mass concentration, cement dosage and synergist dosage on the fluidity, bleeding rate and compressive strength of backfill materials. In addition, the optimal mix proportion was selected and engineering test was carried out based on a coal mine filling project in Shanxi. The experimental results show that the CFBFA requires a large amount of water and has a high activity. The mass concentration and cement dosage are the key factors affecting the performance of the backfill materials. The higher the mass concentration, the worse the flowability of the filling slurry, the lower the bleeding rate, and the higher the strength of the filling body. The higher the cement dosage, the better the flowability and bleeding rate of the filling slurry, and the higher the strength of the filling body. Without the addition of synergist, the mass concentration is below 0.555, and the cement dosage is 200 kg/m3, the filling slurry meets the design requirements of flowability no more than 20 s and 28 day compressive strength no less than 3.0 MPa. However, the bleeding rate is greater than 2%, which does not meet the design requirements. The synergist can significantly improve the flowability of the filling slurry, reduce the bleeding rate, and reduce the cement dosage by up to 90 kg/m3. The suitable dosage of synergist is 5.0 kg/m3. Engineering tests have shown that the addition of synergists significantly improves the mixability and pumpability of the filling slurry. The flowability, bleeding rate, and compressive strength of the filling material prepared on site with a mass concentration of 0.595, cement dosage of 120 kg/m3, and synergist dosage of 5.0 kg/m3 can meet the engineering design requirements.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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