YANG L H, ZHAO P Y, GUO X S，et al. Study on influence mechanism of rheological characteristics of backfill slurry on bubble stability［J］.Journal of Henan Polytechnic University（Natural Science），doi: 10.16186/j.cnki.1673-9787.2024040055

doi:10.16186/j.cnki.1673-9787.2024040055

Received：2024-04-27

Revised：2024-09-05

Online：2024-11-01

Study on influence mechanism of rheological characteristics of backfill slurry on bubble stability

YANG Liuhua¹, ZHAO Pengyao¹, GUO Xiansheng², YANG Zheng³,

CHEN Shuisheng⁴, JIAO Huazhe¹

（1.School of Civil and Engineering, Henan Polytechnic University, Jiaozuo 454000, Henan, China; 2. Shaanxi Xiaobaodang Mining Co., Ltd, Yulin 719302, Shaanxi,China; 3. Linzhou Heavy Machinery Group Co., Ltd., Anyang 719302, Henan,China; 4. School of Mechanical and Power Engineerng, Henan Polytechnic University, Jiaozuo 454000, Henan, China）

Abstract: Cemented paste backfill slurry is a typical solid-liquid-gas three-phase suspension. Bubbles not only affect its rheological properties, but also determine the pore structure after hardening. With the widespread use of admixtures such as air-entraining agent and water reducing agent in backfilling, the control of bubble stability in slurry has gained attention. [Objective] The purpose of this study is to deeply explore the various factors affecting the bubble stability of the slurry, so as to optimize the rheological and mechanical properties of the slurry, so as to improve the filling quality, and is expected to provide a more scientific theoretical basis for the preparation and application of the filling slurry, which is of great significance for improving the efficiency of mineral resources development and utilization in China, reducing production costs, and protecting the environment. [Methods] Firstly, in order to certify the stability of bubbles in slurry, the density of fresh slurry and the shrinkage and density difference after 24 hours of curing were tested under different slurry viscosities and mixing speeds. Secondly, a theoretical model of bubble stability was established based on Stokes theory, and the critical slurry viscosity for bubble stability under dynamic conditions and static conditions was predicted respectively. Finally, the influence mechanism of rheology on bubble stability was analyzed by combining physical experiments and theoretical prediction results. [Results] The deformation and migration of bubbles in the slurry are affected by the rheological parameters. When the slurry viscosity is lower than the dynamic critical value(=1.0238Pa·s), the bubbles are not easy to be squeezed and discharged during the mixing process. When the slurry viscosity is higher than the static critical value(=0.7916Pa·s), the bubbles have a large buoyancy force and resistance and are difficult to escape, therefore, they are retained in the backfilling body until they are condensed to form a pore structure. [Conclusion] Although stable bubbles are easy to condense in the slurry to form a pore structure, the unstable bubbles also exacerbate the backfilling shrinkage and the density difference between the upper and lower layers. Therefore, it is important to optimize the slurry viscosity to improve the backfilling quality. This study points out the direction for the control of bubble stability of the backfilling slurry, and provides a theoretical basis for the development of high-foam backfilling technology.

Key words: backfilling slurry; bubble; viscosity; shrinkage; density difference

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