Effect of Tailings Fine Content on the Properties of Cemented Paste Backfill from the Perspective Packing Density

Jingping Qiu,Jianwen Wang,Zhenbang Guo,Xiaogang Sun,Tingting Zhang,Haijun Wang,Changsuo Zhang,Yun Duan

doi:10.1155/2021/9947620

Abstract

In order to quantitatively study the influence of tailings fine content on the properties of cemented paste backfill (CPB) and further understand the mechanism of tailings fine content acting, the concept of packing density was introduced in this study. The packing density of each tailings sample was measured by the wet packing method after the samples with various fine contents were prepared. Moreover, CPBs with different tailings fine contents were tested by the mini slump test, rheological test, uniaxial compressive strength (UCS) test, and mercury intrusion porosimetry test. The results demonstrated that the flow spread and UCS both increase first and then decrease with the increase of tailings fine content, while the yield stress shows an opposite trend. The fine content of tailings affects the flowability of fresh CPB mainly through the packing density. When the fine content is high, the influence of the specific surface area of tailings cannot be ignored. The packing density is an important factor affecting the strength of CPB, and there is an obvious linear relationship between the packing density and UCS. The pore structure of CPB samples with different tailing fine contents is significantly different, and the macroscopic packing density changes the strength of CPB by affecting the microscopic pores.

Highlights

Mining activities will inevitably have adverse effects on the environment, such as the generation of solid wastes and geological disasters such as surface collapse and dam failure of tailings ponds [1,2,3,4,5]
It can be clearly seen from the figure that when the W/S ratio is less than the basic water ratio, the solid concentration increases with the increase of the W/S ratio. is is because the amount of water mixed at this time is not enough to fill all the voids among the particles, and the formation of liquid bridges will reduce the particle spacing [40]
(2) With the increase of tailings fine content, the flow spread of fresh Cemented paste backfill (CPB) increases first and decreases significantly, while the yield stress shows an opposite trend. ere is an exponential relationship between flow spread and yield stress of fresh CPB. e tailings fine content mainly affects the flowability and rheological properties of the CPB slurry through the packing density, but when the fine content is high, the influence of specific surface area of tailings cannot be ignored

Summary

Introduction

Mining activities will inevitably have adverse effects on the environment, such as the generation of solid wastes (tailings and coal gangue) and geological disasters such as surface collapse and dam failure of tailings ponds [1,2,3,4,5]. CPB is generally composed of tailings, cementitious materials, and mixing water [13,14,15]. Xiapeng et al [32] studied the effect of initial sulphate content on the rheological properties of CPB. In addition to sulphate content and density, tailings particle size is an important factor affecting CPB properties. Cheng et al studied [37] the effect of tailing particle gradation on the yield stress of fresh CPB. Erefore, it is necessary to further explore the influence of tailings particle size on CPB properties. E purpose of this study is to further understand the influence of tailings fine content on CPB properties and to provide theoretical basis for the design of mine backfill mix Because tailings particles are generally fine, the dry packing method often has great limitations in measuring tailings packing density, so the wet packing method was adopted to measure packing density. e purpose of this study is to further understand the influence of tailings fine content on CPB properties and to provide theoretical basis for the design of mine backfill mix

Experimental

Results and Discussion

Conclusions