Scaled Depth of Burial Explained
The article explores the concept of scaled depth of burial (SD) and its significance in mitigating environmental impacts associated with blasting activities in mining and
In efforts to optimise blasting performance and annual cost savings as part of continuous improvement, engineering trials were designed to trial the effectiveness of Varistem® stemming plugs across a series of blasts. By incorporating the Varistem® stemming plugs into the standard blast design, the trials aimed to evaluate the operational, economic and environmental benefits of incorporating the stemming plugs into the blast design and operational processes.
The primary objectives of the trials were to:
The trial blasts were carefully monitored and documented, with performance metrics compared against baseline data from conventional blasting practices. This case study summarises the findings and provides recommendations for potential full-scale implementation.
Based on the results obtained from the trial a clear opportunity to optimise the blasting pattern was indicated by increasing the burden spacing from 1.1 m to 1.2 m, potentially up to 1.25 m. Table 1 shows the comparative savings of using Varistem® stemming plugs at increased burdens of 1.2m and 1.25m respectively, indicating significant decreases in unit operating costs of up to 8.6%.
Table 1: Unit Cost Comparison
| Parameters | Current Baseline | With Varistem® (1.2m burden) | With Varistem® (1.25m burden) |
|---|---|---|---|
| Drift section | 3.5 m x 3.5 m | 3.5 m x 3.5 m | 3.5 m x 3.5 m |
| Burden | 1.1 m | 1.2 m | 1.25 m |
| Number of sections | 82 | 75 | 72 |
| Hole length | 14 m | 14 m | 14 m |
| Holes per section | 6 | 6 | 6 |
| Rock density | 3.1 ton/m³ | 3.1 ton/m³ | 3.1 ton/m³ |
| Mining block tonnage | 13 672 tons | 13 672 tons | 13 672 tons |
| Stemming length | 0.4 m | 0.4 m | 0.4 m |
| Total drill holes | 492 | 450 | 432 |
| Total drilled meters | 6 888 m | 6 300 m | 6 048 m |
| Blasted length | 90 m | 90 m | 90 m |
| Ton/m | 2.0 | 2.2 | 2.3 |
| Drilling cost | $ 0.85/m | $ 0.85/m | $ 0.85/m |
| Total D&B cost per block | $ 33 330 | $ 31 708 | $ 30 444 |
| Unit cost | $ 2.44/ton | $ 2.32/ton | $ 2.23/ton |
| Unit savings | — | $ 0.12/ton | $ 0.21/ton |
| Unit savings (%) | — | 4.9% | 8.6% |
This analysis demonstrates that the use of Varistem® allows wider burden spacing while maintaining effective fragmentation, thereby reducing drilling and explosives consumption.
It is recommended to work closely with operational personnel to ensure that the Varistem® stemming plugs are installed up to the explosive column limit in order to maximize system performance.
It is recommended to expand the blasting pattern by increasing the burden from 1.1 m to 1.2 m in order to achieve annual savings of approximately USD 300,000, including the cost of the Varistem® stemming plugs.
Continuous supervision of operational personnel is recommended to ensure consistent installation of the Varistem® stemming plugs. In some cases, installation may be omitted due to blasting schedule constraints, preventing realization of the demonstrated benefits.
Acquisition and implementation of the Varistem® stemming plugs is recommended in order to achieve the continuous improvement opportunities identified in this report.
It is recommended to place detritus material above the Varistem® device to achieve improved blasting performance and results.
The article explores the concept of scaled depth of burial (SD) and its significance in mitigating environmental impacts associated with blasting activities in mining and
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A POTENTIAL REASON FOR ADVERSE BLASTING OUTCOMES? INTRODUCTION A critical design parameter that needs to be selected during the drilling and blasting design process is