Review of pre-conditioning practice in mechanized deep to ultra-deep level gold mining: 26th International Symposium on Mine Planning and Equipment Selection (MPES2017). 29 – 31 August 2017, Luleå, Sweden
Mining in South Africa has reached ultra- deep levels, approaching 4000m, requiring appropriate mining practices which stabilize ground conditions. As mining depth increases, the stress levels ahead of the mining faces increase with high probability of experiencing face bursting. Face- perpendi...
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| Main Authors: | , |
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| Format: | Presentation |
| Language: | English |
| Published: |
2022
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| Subjects: | |
| Online Access: | https://www.researchgate.net/publication/320552233_Review_of_pre-conditioning_practice_in_mechanized_deep_to_ultra-deep_level_gold_mining http://hdl.handle.net/11408/4957 |
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| Summary: | Mining in South Africa has reached ultra-
deep levels, approaching 4000m, requiring appropriate mining
practices which stabilize ground conditions. As mining depth
increases, the stress levels ahead of the mining faces increase
with high probability of experiencing face bursting. Face-
perpendicular pre- conditioning practice was employed in order
to fracture the rock mass ahead of the face, so as to transfer
stress further away from the face. Although the face-
perpendicular pre- conditioning practice has been employed on
most deep level gold mines in South Africa, rockbursts are still
being experienced. The rockburst related accidents result in
minor and major injuries to fatal injuries as well as machinery
damage. This paper aims to highlight the effectiveness of a
revised practice of four face-perpendicular pre-conditioning to
five face-perpendicular pre-conditioning blasting technique in
a mechanized ultra-deep level gold mine in South Africa. The
investigations involved the use of underground monitoring
instrumentations for the effectiveness of preconditioning
practice, these include; micro seismic monitoring, Ground
Penetrating Radar and borehole camera. Fragmentation of the
extracted ore, fracturing on the face, side and hangingwall were
taken into consideration. Vantage numerical modelling
software was used to generate sigma 1 and safety factor within
the section and ahead of the stope faces. It was found that most
of the faces where four face-perpendicular pre- conditioning
was practiced were not effectively pre- conditioned. The panels
had high seismic activities and many large magnitude events
compared to five face-perpendicular pre-conditioned faces.
Fragmentation and face fracturing were found to have
improved during the implementation of five face-perpendicular
preconditioning practice. The maximum principal stress (sigma
1) and Safety Factor were found to be higher during four face-
perpendicular preconditioning practice, while these were found
to be reduced during the five face-perpendicular
preconditioning practice. |
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