Abstract

A surface gold mine wishes to develop a new pit (Pit A) as part of its mining schedules. The proposed pit outline is about 300 m to the closest community. Blasting operations in Pit A would potentially create undesirable environmental impacts including fly rocks, ground vibrations and air blasts to neighbouring communities. Integration of proper planning tools or protocols for blasting at Pit A is the major concern of the Mine. Due to safety reasons, management wishes to explore the best blasting protocols that will restrain any blast impact to a 250 m buffer from the proposed pit outline. The Kuz-Ram fragmentation model was used to generate the optimal geometric parameters required for blasting at Pit A. Ground vibration, air blasts and fly rock impact prediction models were used to estimate the associated blast impacts to the neighbouring community. The predictions were made for blasting the oxides, transition and fresh rock formations to be encountered in Pit A. The predicted ground vibration and air blast levels were compared with the Ghanaian regulatory threshold of 2 mm/s. The predicted maximum fly rock distance (235 m) from the pit outline is within the established 250 m clearance buffer zone. The geometric drill and blast parameters and associated single-hole firing charges were used in the prediction models. The predicted results from this study will assist the surface gold mine to properly execute safe blasting operations with minimal impact to the neighbouring community. Due to known scattering of NONEL explosives in initiation systems, electronic initiation systems are recommended for blasting in the new pit.

Highlights

  • Planning the extraction of any mineral deposit requires the consideration of several parameters including but not limited to the quantity and quality of the deposit and the associated impacts of the mining operations

  • Due to known scattering of NONEL explosives in initiation systems, electronic initiation systems are recommended for blasting in the new pit

  • The historic blast performance data from the active pit were used to establish the site-specific constants in terms of the Rock Transmission Factors (RTF) according to the Gustaffson and the United States Bureau of Mines (USBM) models, and the air pressure referenced from atmospheric pressure (Po)

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Summary

Introduction

Planning the extraction of any mineral deposit requires the consideration of several parameters including but not limited to the quantity and quality of the deposit and the associated impacts of the mining operations. In cases where blasts are conducted close to human settlements, many interests are given to but not limited to the effects of fly rock, ground vibration and air blast. On-bench blasting would create considerable environmental impacts notably fly rocks, ground vibrations and air blasts. This requires that prior measures are taken to minimize or eliminate these impacts on the surrounding settlements during mining operations and conform to the national guidelines. The study identifies appropriate measures required for blasting at Pit A that ensure safe blasting operations. Integration of these measures during blasting operations at Pit A is expedient to the success and peaceful co-existence of the mine in the community

The Study Area
Proposed Mining at Pit A
Historic Blast Performance
Materials and Methods
Ground Vibrations Impact Predictions
Fly Rock Impact Predictions
Air Blast Impact Predictions
Findings
Conclusions and Recommendations
Full Text
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