The paper describes the first attempt of introducing paste backfill in Japan at the Toyoha mine. In 1997, the Metal Mining Agency of Japan (MMAJ), which was reorganized in February of 2004 and currently works as the Japan Oil, Gas and Metals National Corporation (JOGMEC), launched a five year long research program to innovate mining technologies and systems required to save and efficiently use energy in mines. As a part of the program, studies on paste backfill technology and its implementation in Japan were involved.
The Toyoha mine was selected as the site for testing paste backfill, since the mine is being operated under an extremely high rock temperature environment. In order to improve the underground climate, the mine decided to introduce paste backfilling and effectively reduce heat flows from mined-out stopes.
The first flow test was performed on surface in 1998 and the second flow test was carried out underground in 2001 after having installed the paste fill plant and underground pipelines. The underground test was, however, abruptly discontinued by a mechanical failure, which happened to the PPSM thickener whose bolts holding the drive head at the top of the thickener were broken.
After the unpredicted interruption of the paste backfilling test, we have carried out a series of ventilation analyses to evaluate the energy saving effects with paste backfilling under a high rock temperature condition. And we have clarified that remarkable energy saving can be expected by reducing heat flows from mined-out stopes and energy consumption required for underground refrigeration. In addition, it is found that significant cost saving can be also anticipated by curtailing volume of the tailings impoundment and its construction cost.