Properly illuminated mine sites are essential for safety and operational efficiency, as well as providing a way for miners to reduce costs and improve energy usage through innovative lighting solutions that incorporate light emitting diode (LED) technology.
Underground mines are the most difficult places to illuminate, being dynamic environments that include dust, confined spaces, explosive gases, hazardous machinery, and surfaces that reflect light poorly and offer low visual contrasts.
Insufficiently lit mine sites can significantly impact safety, leading to decreased worker alertness, productivity, reaction times, and cognitive function. Additionally, poor lighting increases the risk of accidents, health issues, sensitivity to light, and fatigue.
It also offers a pathway to achieve significant efficiency gains, as lighting accounts for approximately 15 per cent of the total electricity consumed by the mining industry.
Recent technological advancements present opportunities to enhance energy efficiency right from the design stage.
LED luminaires can result in about 50 per cent energy cost savings compared to high-intensity discharge lamps, and 30 to 40 per cent compared to fluorescent lights.
This level of improvement is driving a swift adoption of LED technology across various industries, especially in mining.
A 2022 study found that low-light environments significantly impact human physiology, psychology, and behaviour, leading to increased errors in work and a higher incidence of accidents.
The study developed a coal mine lighting simulation experiment system that included a physiological indicator testing system and a miners’ working simulation system. It examined the effects of varying illumination levels on heart rate, electrodermal activity, and respiration.
The results showed that a lack of illuminance had a significant negative correlation with all three indicators, with heart rate the most impacted when illuminance was a quarter of normal levels.
By contrast, respiratory rate and electrodermal activity are noticeably affected at 5 per cent of normal levels, which is also the level of illumination when accidents tend to increase.
As part of their ongoing mine illumination work, researchers from the US National Institute for Occupational Safety and Health (NIOSH) developed an LED cap lamp in two phases. The first phase focused on enhancing light colour, while the second phase aimed to further improve performance by adjusting the lighting distribution.
During the research, it was discovered that the common method of increasing illumination to address the reduced light reaching the retina of older individuals also resulted in increased glare and reduced battery life. NIOSH’s approach for age-related issues was to manipulate the visible light colour spectrum of the cap lamp.
In the low-light ambient conditions typical of underground mines, an increased short-wavelength spectral content has been shown to enhance visual performance, as the eye is more sensitive to that wavelength of visible light. These findings were integrated into the development of the LED cap lamp, which specifically enhanced these short wavelengths of light.
A comparative study was conducted using the phase one prototype LED cap lamp, a commercial LED, and an incandescent cap lamp. The results indicated significant improvements for the oldest age group of test participants: 23.7 per cent faster floor hazard detection, 15 per cent faster peripheral motion detection (essential for detecting moving machinery hazards), and a 53.8 per cent reduction in disability glare.
The LED cap lamp also had 65 per cent less energy usage compared to the incandescent cap lamp. In further testing, the phase two LED cap lamp was compared, showing improved results of 94 per cent faster trip hazard detection and 79 per cent faster peripheral motion detection.
The phase two lamp also had no increase in glare and was up to 50 per cent more energy efficient than commercially available LED cap lamps.
