Abstract: In order to explore the mix proportion of sealing slurry with the character of magnet for gas drainage borehole, carbonyl iron powder with micron size (3 μm) and ferro-ferric oxide (Fe₃O₄) with nanoparticle size (200 nm) were selected as magnetic particles, and polyvinyl alcohol and water in a certain proportion were taken as the main base liquor of sealing slurry. Then the slurry mixing ratio experiments under multi-level and multi-factor conditions were carried out according to different mass fractions of magnetic particles in the slurry and different types and particle sizes of magnetic particles. Similar material simulation experiments were conducted by means of three-dimensional magnetic imaging system. Magnetic tracking effect of the slurry was verified. The results show that adding a certain amount of Fe₃O₄ into the slurry with carbonyl iron powder as the main solute can greatly reduce the sedimentation rate of the sealing slurry, that after the sealing of similar materials, the magnetic properties in the slurry can better characterize the filling and bonding cementing position of the sealing slurry in similar materials, and that in similar materials,the internal cracking will be more obvious in areas with larger magnetic strength.

Key words: sealing slurry flow trajectory, magnetic imaging, magnetic particles, sealing slurry, gas drainage borehole