全尾膏体动态压密特性及其数学模型

Dynamic thickening characteristics and mathematical model of total tailings

深锥浓密机是膏体技术中尾矿浓缩工艺的关键设备,深锥浓密机底流质量分数与泥层压力密切相关,孔隙比是表征底流质量分数的重要物理参数,但是孔隙比随泥层压力的变化规律并不清晰。针对这一问题,首先,提出了尾矿可浓缩性能表征的物理概念——有效孔隙比,即孔隙比减去饱和孔隙比;其次,采用某矿全尾砂进行了动态压密试验,结果表明,当泥层高度为31~200 mm,对应泥层压强为2 477~4 410 Pa,获得的底流质量分数范围为73.26%~78.30%,该质量分数范围对应的有效孔隙比为0.433~0.191。回归有效孔隙比与泥层压强数学关系得知,二者遵循幂函数Allometric模型;最后,提出了膏体动态压密数学模型,并根据模型曲线,将膏体动态压密分为3个区域:(1)线性压缩区,孔隙比随泥层压强增大而基本呈线性关系,孔隙比变化幅度较大;(2)衰减压缩区,随着压强继续增大,孔隙比下降幅度变缓,膏体趋于饱和;(3)恒定压缩区,该区域膏体达到饱和状态,孔隙比随着压强增大而基本恒定。该研究揭示了尾矿浓缩过程中孔隙比随泥层压强的变化规律,为浓密机设计及运行提供理论依据。

The key equipment of thickening process in the action of cemented paste backfill(CPB) is deep cone thickener(DCT).The underflow mass fraction of DCT is significant related to the slurry pressure. And the void ratio is an important representation parameter of the underflow mass fraction. However, the change rule between the void ratio and the slurry pressure is not clear. For the interpretation of the problem aforementioned, a new concept for the tailings thickening degree is proposed and named as effective void ratio(EVR). The EVR is referred to void ratio minus saturated void ratio. A total tailings dynamic thickening experiment is conducted. The results show that the slurry pressure is between 2 477-4 410 Pa as the slurry height is between 31-200 mm. The underflow mass fraction is calculated as 73.26%-78.30%, which corresponding the EVR is 0.433-0.191. The regression result indicates that EVR and slurry pressure follow the power function. Moreover, the paste dynamic thickening model is proposed.According to this proposed model, the paste dynamic thickening behaviour is divided into three processes:(1) linear thickening zone,with the increasing of slurry pressure, the void ratio decreases quickly almost as linear,(2) attenuation compression zone, with the slurry pressure increasing continues, the void ratio decreases gradually and the paste tends to be saturated,(3) constant thickening zone, the tailings achieve saturated state and the void ratio become constant. This study reveals the change rule between the void ratio and slurry pressure in the process of thickening and provides the theoretical foundation for the thickener design and operation.