There is a general consensus across industries that sustainability is no longer just a corporate buzzword, but a strategic business imperative. Dr Dhoorgapersadh says sustainable practices support ecological, human and economic health and vitality.
“Sustainability presumes that resources are finite and should be used conservatively and wisely with a view to long-term priorities and consequences of the ways in which resources are used. In simplest terms, sustainability is about our children and our grandchildren, and the world we will leave them,” explains Dr Dhoorgapersadh.
Blasting’s environmental impact
Blasting activities are said to have their fair share of environmental impact. Commenting on some of the common impacts on the environment, Dr Dhoorgapersadh makes special mention of blast-induced ground vibration, airblast and flyrock.
Blast-induced ground vibration, he explains, is a transient pressure pulse that traverses through a rock mass as a result of energy released during a blast. This energy released at the blast site is sufficient to cause permanent damage to the rock mass. Outside of this area the energy is elastic, so that the particles of the rock mass are not permanently deformed or displaced. After the energy passes, the particles return to their original resting position.
As a result of this displacement, particles impact other particles, and this continues as the energy is transmitted away from the blast site. There are three types of waves that occur due to the vibrations caused by a blast namely: air waves, surface waves and body waves.
“It is common practice to measure blast vibration amplitude as particle velocity (mm/s) or the speed at which a particle vibrates. Surface waves travel along the surface of the Earth. Body waves travel through the Earth’s interior and can reach speeds of up to 7 600 m/s. The Mine Health and Safety Act and Regulations specify recommended vibration levels for different structures as below,” he says.
| Blasting Situation | Recommended Max Level (mm/s) |
| National Roads / Tar Roads / Railways | 150 |
| Powerlines – Pylons | 75 |
| Water wells / Telecoms towers | 50 |
| Transformers | 25 |
| General houses of proper construction | 25 |
| Houses of lesser proper construction | 12,5 |
| Rural building | 6 |
Airblast is an atmospheric compression wave resulting from the detonation of explosives. Airblast includes noise but also frequencies which cannot be heard by the human ear. It can occur through stemming, pre-existing and blast-induced fractures in the face and forward movement of the rock mass itself. It is propagated by a series of overpressures that decrease in intensity with increasing distance from the blast.
Flyrock is the undesirable throw of debris from a blast. Flyrock generates close to the air/rock interfaces, collar regions of blastholes, free face of a bench blast and secondary blasting. Flyrock occurs when the state of confinement of explosive charge is insufficient for applied evacuation radius, resulting in excess energy for the required task, causing projection of rock fragments beyond the clearance radius. It is caused by design faults, deviations in implementation and unforeseen geological conditions.
Design faults include inappropriate choice of burden for planned charge configuration; inappropriate charge concentration for drilled burden or stemming lengths; and deviations in implementation – for example, deviation of actual stemming length or front row burdens.
“Under ideal conditions, the detonation of ammonium nitrate-based explosives should produce carbon dioxide (CO₂), water (H₂O) and nitrogen (N₂). When excess fuel is present, carbon monoxide (CO) is produced and when an excess oxidiser is present nitric oxide (NO) is produced,” explains Dr Dhoorgapersadh.
Addressing environmental impacts
Factors that affect ground vibration include mass of explosives detonated per delay, blasthole pattern/initiation timing and sequence, distance from blast to the point of monitoring, direction of direct energy propagation, and rock mass geology.
“The several methods the industry has used to limit ground vibrations include optimising effective burden, sub drilling – minimising to 8-10 times the hole diameter, and minimisation of explosives mass per delay. Blasts should be initiated from the free face and delay intervals should be kept large enough to allow for ease of breakage of successive rows,” explains Dr Dhoorgapersadh.
In order to minimise airblast and noise, it is important to ensure sufficient stemming is used (20–40-hole diameters), use in-hole detonators and ensure adequate burden on the hole crest. Laser profiling should be used to measure face uniformity and, where applicable, the charge configuration should be altered to account for irregular faces. Detonation cord should be avoided, and mechanical breaking should be used, if possible, over secondary blasting.
Other measures to reduce airblast and noise include:
- Creation of earth mounds between mine and areas of concern
- Planting of indigenous trees and plants to create screens
- Avoid the following:
- Blasting when there is a low, dense cloud-base
- Cloud cover > 50%
- Wind blowing > 10 km/h to area/s of concern
- Early or late in the day
- Use of electronic detonators – single hole firing
- Depth of blast – Reduce number of rows
- Practise bottom hole priming rather than collar priming
- Avoid very short delay periods
- Increase front row burden if the face is uneven
“Firing of large, well-designed blasts is recommended thus avoiding small blasts. Blasting during working hours or times with high ambient noise is preferred,” says Dr Dhoorgapersadh.
When it comes to flyrock, he says, a good blast design is the primary method to avoid it. While the blast pattern may be satisfactory, drilling inaccuracies or incorrect blasthole angles can cause significant deviations from the planned pattern with resultant excessive noise, vibrations and/or fly rock. The extra time spent on making sure that the blasthole is in the right position is especially warranted. Instruments should be used to set out the drilling pattern. He, however, warns that there will be difficulty in estimating the burden in hilly terrain.
“The correct charge weight must be employed in the blast hole. When using Ammonium Nitrate – Fuel Oil (ANFO) or any other free-running explosive, pour measured quantities of the explosives into the hole and monitor the build-up of the explosive column by tape measure or wooden pole. This is to avoid overcharging, which may result from fissures or chambers in the rock,” advises Dr Dhoorgapersadh.
In addition, he says, there have been instances of covers being used to minimise the effects of fly rock. This should be avoided – just like when a hierarchy of controls is applied – a cover is the last resort. Elimination of the hazard by proper blast design and drilling must take priority.
Ensuring environmental stewardship
In its quest to ensure environmental stewardship, BME has over the years put in place a number of initiatives. For example, the company has been at the forefront of promoting the use of dual salt blasting emulsions. The safety and environmental advantages of dual salt emulsions are gaining more attention from the mining sector as companies pursue more ambitious environmental, social and governance (ESG) goals. Dual salt emulsions have proven themselves as less harmful in terms of potential nitrate contamination and greenhouse gas emissions.
Some of the major benefits of this technology include reduced nitrogen oxide (Nox) fumes, optimal blast fragmentation, minimal nitrate leeching, enhanced shelf life and storage stability, improved energy control, which allows for fine-tuning of energy output and Velocity of Detonation (VoD) for different rock conditions.
“Dual-salt Ammonium Nitrate Calcium Nitrate (ANCN) emulsions offer superior oxygen-balancing flexibility, enabling more precise stoichiometric control. This enhances stability, while reducing NOx generation during detonation,” says Dr Dhoorgapersadh.
Since the 1980s, BME has been using recycled waste oil in explosives which promotes circular economy principles. The use of used oil minimises the impact on the environment without any adverse effects on emulsion quality or performance. It reduces the need for virgin fuel oils and diverts hazardous waste from landfills or incineration. This gives a responsible end-use for hazardous waste oil.
The use of high-shear emulsion Innovex 300D, a mechanised solution, ensures increased resistance to dynamic water, thus reducing the likelihood of misfires and incomplete explosions. It is suitable for highly friable and fractured geological conditions. High-shear emulsion offers resistance against free ammonia and acidic sulphate soil conditions.
The company has also invested in Hydrogen Peroxide Emulsion (HPE) technology, which enhances mining performance by eliminating NOx gas, nitrate leeching, and ammonia-related issues. It enables substantial CO₂ emissions reduction without compromising explosive performance. On the EU average, 1 kg of AN emulsion emits only 2,3 kg of carbon dioxide during the oxidiser phase.
“In contrast, the production of HPE emits just 0,23 kg of CO₂, signifying a substantial 90% reduction. Another benefit of HPE production is its energy efficiency. The base HPE uses established mixing techniques in a low-energy-intensity modular plant. In contrast, the production of AN emulsion is relatively energy-intensive and not carbon neutral,” explains Dr Dhoorgapersadh.
Key successes
Commenting on some key successes of these initiatives, Dr Dhoorgapersadh notes that BME currently consumes 30-million litres of used oil annually. Used oil recovery and waste recycling saves resources such as diesel and water by using less traditional fuel.
“A rigorous trial was conducted to evaluate the environmental effects of HPE versus Ammonium Nitrate Emulsion (ANE) on water, sludge/mud and air quality. Water analysis showed a significant reduction in nitrogen compounds, including ammonium and nitrates when using HPE compared to ANE. Ammonia levels during ANE operations ranged from 0,90 to 4,64 ppm, while HPE operations recorded lower levels between 0,03 and 0,77 ppm. This prompted the investment in upscaling the HPE technology,” says Dr Dhoorgapersadh.
Tech to the fore
Technology is playing a big role in sustainability. According to Dr Dhoorgapersadh, as technological advancements continue, blasting practices in the mining industry have radically transformed. Modern blasting techniques, advanced equipment and a growing emphasis on safety and sustainability drive precision and efficiency in mining activities.
Several technologies have come to market to enhance safety and productivity in blasting and these include:
Remote blasting systems: Remote blasting systems utilise drones and robotics to allow operators to execute blasts from a safe distance. They reduce human exposure to hazardous environments, ensure precise detonation and minimise errors.
Blast hole drilling: Automation in blast hole drilling has further transformed the blasting process by enabling autonomous drilling rigs to accurately position holes, optimise drilling patterns and adapt in real time based on geotechnical data. Automation enhances drilling precision, reduces time and ensures consistent hole quality.
Data-driven blasting: The industry is integrating data analytics and artificial intelligence (AI) to analyse geological and operational data, optimising blast designs, timing and parameters to improve mineral recovery and minimise environmental impacts. These advancements reduce costs and ecological footprints.
Other cutting-edge blasting technologies include:
Precision blasting: Advancements in sensor technologies and real-time monitoring systems have empowered mines to refine blast designs and maximise energy efficiency. These innovations help rock fragmentation and reduce environmental impact, including noise and vibration.
Controlled blasting: In addition to high accuracy, integrating advanced sensors together with monitoring systems, has enabled mines to achieve substantial control during blasting operations. Enhanced control is crucial for ensuring safety and preventing infrastructure damage. By closely monitoring factors such as blast timing, placement and energy release, mines can effectively minimise risks, protect surrounding structures and communities and reduce environmental impact, while maintaining and optimising overall blast performance.
Pre-splitting: By establishing predefined fractures, pre-splitting ensures that blast energy is directed more precisely, leading to safer and more efficient excavation. This ensures improved control over fragmentation, enhanced stability of rock walls, and a reduction in fly rock.
Taking responsibility
As much as new technologies are being developed to optimise blast efficiency while reducing environmental impacts, Dr Dhoorgapersadh stresses that each stakeholder is responsible for their part in contributing to sustainable mining.
Explosives manufacturers, he says, must strive towards reducing their carbon footprint in the production of explosives. While this can be done on a large scale such as the nitrate-free explosives initiatives, it can also be done by monitoring current energy use on manufacturing plants, asset integrity and waste management.
“Complacency can also result in inadequate blasting results. Human errors in the blast design, drilling and charging steps will contribute to poor blast performance. This leads to requiring secondary blasting, thus more explosives are used and more air blast, fly rock and emissions are subsequently produced,” warns Dr Dhoorgapersadh.
