磷石膏充填体强度和浸出毒性的温变规律

Temperature-depending characteristics of strength and leaching toxicity of phosphogympsum-based cemented paste backfill

针对矿井不同时空下环境温度多变的实际问题,通过开展不同养护温度下的磷石膏充填体单轴抗压强度实验、浸出毒性实验和微观分析实验,考察环境温度对磷石膏胶结充填体的力学性能和浸出毒性的影响规律。结果表明:磷石膏充填体早期强度与养护温度呈指数关系,养护温度为10、20、30和40℃时,磷石膏充填体3 d的单轴抗压强度分别为0.055、0.096、0.186和0.527 MPa,而充填体后期(28 d)的单轴抗压强度与养护温度无显著关系;总磷的浸出量随养护温度先下降后略有上升,而氟化物的浸出量与养护温度成反比关系,在30℃时,总磷和氟化物的浸出量分别为0.05和8 mg/L;磷石膏充填体混合相的前期水化产物CH、AFt、C-S-H随温度升高而增加,而后期水化反应因未反应颗粒被胶凝产物包裹而受阻,可见温度通过调整水泥水化反应和磷石膏缓凝作用而影响充填体强度和浸出毒性规律,工程应用时需要根据现场环境进行配比参数调整。

Aiming at the practical problem of changeable environmental temperature in different time and space of mine,the influence of environmental temperature on strength and leaching toxicity of phosphogypsum cemented filling body was investigated by uniaxial compressive strength test,toxicity leaching test and microscopic analysis under different curing temperature.The results show that the early uniaxial compressive strength(UCS)of phosphogypsum filling is exponentially related to the curing temperature,and the UCS after curing for 3 d at 10℃,20℃,30℃and 40℃are 0.055 MPa,0.096 MPa,0.186 MPa and 0.527 MPa respectively,while the later UCS(28 d)of the filling body has no significant relationship with the curing temperature.The leaching amount of total P decreases first and then increases slightly with the curing temperature.And the leaching amount of fluorideis founded to decrease with the increasing of curing temperature(within the studied range).The leaching amount of total P and fluoride are 0.05 mg/L and 8 mg/L at 30℃.The early hydration products CH,AFt and C-S-H of phosphogypsum-based filling body increase with the increase of temperature,while the later hydration reaction is hindered by the inclusion of unreacted particles by cementitious products.It can be seen that the temperature will affect the cement hydration reaction and phosphogypsum retarder and thus to influence the UCS and toxicity of backfill,so it is necessary to adjust the proportioning parameters according to the site environment in engineering application.