Rock drilling operations are essential in industries such as mining, construction, and oil & gas, but they come with one significant downside—noise pollution. The powerful percussion of drilling machines, high-pressure air compressors, and mechanical vibrations generates sound levels that can reach harmful decibel ranges. This noise disturbs the surrounding environment and poses serious health risks to workers, including hearing damage, stress, and reduced concentration. Furthermore, excessive noise can negatively impact community relations and lead to regulatory challenges.
Hazards of rock drilling machinery noise
Damage to human hearing
People hear sound because the sound pressure transmitted in the atmosphere acts on the eardrum of the human ear, and from the neural receptors to the brain. If exposed to noise for a long time, it can cause hearing loss and hearing retardation.
Induce a variety of diseases
①Noise acts on the human central nervous system, causing symptoms such as dizziness, brain swelling, insomnia, dreaminess, palpitation, and general fatigue.
② It affects human organs, causes changes in gastrointestinal function, causes indigestion, loss of appetite, nausea, and vomiting, and leads to an increased incidence of gastric ulcers.
③ It makes the sympathetic nervous system, causing tachycardia, arrhythmia, abnormal electrocardiogram, increased blood pressure, and even causes more serious heart disease.
④ It affects the metabolism of human nutrition, resulting in a lack of many vitamins.
⑤ Long-term noise exposure can reduce people’s immunity, impair physiological function, and accelerate the aging process.
It affects the work efficiency of operators
In a high-noise environment, the operator’s attention is not easy to concentrate, which leads to a decrease in work efficiency and an increased risk especially prone to accidents.
Damage to buildings and structures
Noise is formed by acoustic vibration. High-power noise transmission in the air can cause strong air vibration, which has a destructive effect on surrounding buildings, structures, and even mechanical structures. It may also affect the operation of automatic control, remote control systems, or equipment.
The noise of rock drilling machinery has multiple hazards to human health and the environment, including but not limited to hearing loss, sleep disturbance, communication difficulties, reduced quality of life, and disturbance to wildlife. Therefore, reducing noise pollution not only helps to protect the workers’ health but also improves the ecological environment.
Understanding the Noise in Rock Drilling Machinery
Rock drilling machinery is inherently noisy due to the powerful mechanical and pneumatic forces involved in the drilling process. Understanding the types of noise generated, their sources, and the regulatory frameworks surrounding noise levels is essential for developing effective noise reduction strategies.
Types of Noise Generated
- Impact Noise (from Percussion):
This is one of the most prominent sources of noise in rock drilling, particularly in Down-the-Hole (DTH) and top hammer drilling. Impact noise occurs when the hammer strikes the drill bit with high energy, breaking through rock formations. The percussive action, while necessary for drilling efficiency, generates sharp, high-decibel noise waves that can be harmful to both workers and the surrounding environment. - Mechanical Noise (from Engines and Hydraulics):
The engines and hydraulic systems powering drilling rigs contribute significantly to noise levels. Hydraulic systems that control movement, pressure, and rotation often emit a steady hum or buzzing sound, while the engine running the machinery can create low-frequency noise that reverberates throughout the site. - Air-Compressor Noise:
In DTH drilling, air compressors are used to provide high-pressure air to drive the hammer. The constant release of compressed air, especially at high volumes, creates a distinct whooshing sound. Air compressors can operate at very high decibel levels, especially in deep-hole or high-pressure drilling scenarios, significantly adding to the overall noise pollution.
Sources of High Noise Levels
- Drill Bits:
The interaction between the drill bit and the rock surface generates noise. Harder rocks, such as granite or basalt, create higher noise levels due to the resistance encountered during penetration. - Hammers:
Both top hammers and DTH hammers are major sources of impact noise. DTH hammers tend to generate more intense, concentrated noise due to their percussive action, making them one of the most challenging noise contributors. - Rigs and Supporting Equipment:
The drilling rig itself, along with supporting equipment such as pumps, winches, and conveyors, all contribute mechanical noise. Rigs operating at high speeds or under heavy load conditions tend to amplify mechanical noise levels. - Air Compressors:
As mentioned, air compressors provide the necessary pressure for DTH systems. The air released during drilling operations creates significant sound, which can be particularly intrusive in residential or sensitive environments.
Regulatory Limits and Standards
Noise pollution from rock drilling is subject to various regulatory standards aimed at protecting workers and surrounding communities. These include:
- OSHA (Occupational Safety and Health Administration): OSHA has guidelines for permissible noise exposure for workers in the United States. The threshold limit is set at 90 decibels (dB) over an 8-hour workday, with required hearing protection for levels exceeding this limit.
- EPA (Environmental Protection Agency): The EPA sets noise pollution standards for industrial sites, which vary by location and type of activity. These regulations are intended to minimize disturbance to local communities, particularly in residential and urban areas.
- Local Regulations: Many regions have their noise ordinances that limit the noise levels of construction and drilling operations. These regulations are often more stringent in areas with high population density, such as cities or near schools and hospitals.
Key Challenges in Reducing Drilling Machinery Noise
Reducing noise in rock drilling operations presents several technical and logistical challenges. Understanding these challenges is key to implementing successful noise reduction measures.
High Impact Forces in Percussion Drilling
The nature of percussion drilling, especially with DTH and top hammer systems, inherently generates high-impact noise. The hammers strike the drill bits with substantial force, which leads to both mechanical shock and acoustic waves. While reducing the intensity of the impact would affect drilling efficiency, managing this force without compromising performance remains a significant challenge.
Solution: Innovations in vibration dampening and improved bit and hammer design aim to reduce the impact forces and absorb shock, thus minimizing noise generation. However, balancing performance and noise reduction is difficult, particularly in hard rock conditions.
Mechanical Noise
The rigs, engines, and hydraulic systems involved in rock drilling operations are major sources of mechanical noise. Rigs that operate with heavy machinery and powerful hydraulic systems produce a consistent hum, which is amplified in large-scale operations.
Solution: Modern rigs are being designed with quieter hydraulic systems and soundproofed engine enclosures to reduce mechanical noise. The use of electric-powered rigs instead of traditional diesel engines also helps to lower the overall noise output, though this is still an evolving technology.
Air Compressor Noise
Air compressors are a crucial component of DTH drilling, but also one of the loudest contributors to drilling noise. The sound of compressed air being released is intense, particularly in high-pressure systems. The challenge is to balance the air pressure required for effective drilling with the need to mitigate sound levels
Solution: Using low-noise air compressors with advanced muffling systems and enclosures can significantly reduce air compressor noise. Additionally, variable-speed compressors can be employed to adjust air output based on the drilling conditions, preventing excess noise when full power is not needed.
Vibration Transmission
In addition to airborne noise, vibrations from drilling machinery cause sound to travel through the ground, further exacerbating the overall noise problem. These vibrations can result in ground-borne noise that affects nearby buildings and structures, especially in urban environments.
Solution: Installing anti-vibration mounts and shock-absorbing systems in the rig can help reduce vibration transmission. Using vibration isolation mats or creating barriers around the drilling equipment can also help minimize the impact of ground-borne noise.
Methods of preventing noise from rock drilling machinery
Basic control method of rock drilling noise
①Starting from the sound source, try to reduce the noise intensity.
Improve or change construction technology to replace high-noise equipment with low-noise equipment. Improve the mechanical design and reduce the original noise. Improve product processing accuracy and assembly quality. Take comprehensive measures to reduce mechanical vibration, etc.
② Take measures on the noise transmission, and try to cut off the connection between the noise source and the noise victim. For example, install mufflers in place to reduce intake and exhaust noise.
③ Take protective measures for people exposed to noise to prevent them from noise hazards. Scientifically take individual protective measures, such as wearing anti-noise earmuffs and reducing the exposure time of operators to noise, etc.
Take measures according to different types of rock drilling machinery
①Noise control of pneumatic rock drill
Among the pneumatic rock drill noise sources, exhaust noise accounts for 87.4%, and other noise accounts for 12.6%. Aerodynamic noise control is the key to noise control of pneumatic rock drills.
②Noise control of hydraulic rock drill
The exhaust noise of the hydraulic rock drill is not as loud as that of the pneumatic rock drill, but it is still seriously harmful to human hearing. The noise of the hydraulic rock drill includes: “injection noise” caused by the airflow of the impact piston hitting the shank adapter, “pressure impulse noise” caused by the instantaneous deformation of the impact piston hitting the shank adapter collision piece, and “structure impact vibration noise” produced by body vibration caused by the impact system. For noise control of hydraulic rock drills, we should pay attention to the impact performance parameters of hydraulic rock drills. Try to make the shank adapter structure conducive to reducing injection noise. To explore the new material of impact piston and shank adapter, Improve the vibration resistance performance to reduce pressure impersonation noise. Focus on reducing structure impact vibration noise.
③ Noise control of hydraulic drilling rig
The noise sources of hydraulic drilling rigs include hydraulic rock drill noise and pump station noise.
Control the noise of the hydraulic drilling rig through 4 points:
A. Reasonably select the performance parameters of hydraulic rock drills.
B. Try to reduce the impact of hydraulic drill structure vibration noise.
C. Increase the rigidity and stability of the hydraulic drilling rig, and take shock absorption measures in many ways to avoid resonance of related components caused by impact vibration.
D. Rationally design supporting systems such as hydraulic pump stations, as far as possible to reduce the noise of hydraulic drilling machines in a non-working state.
④ Noise control of pneumatic rotary drilling rig
The noise of the pneumatic rotary drilling rig is mainly composed of the exhaust noise of the pneumatic motor, the friction noise of the mechanical transmission, and the friction noise of the drilling. Its control can consider two aspects: reasonable selection of pneumatic motor type and performance parameters.
Other prevention and control measures
①Regularly check and maintain rock drilling machinery and equipment to keep them in the best working condition and reduce noise.
②Set up soundproof walls, soundproof covers, or soundproof barriers around the rock drilling machinery to effectively reduce noise transmission to the surrounding environment.
③ Select rock drilling machinery with low design noise to reduce noise during operation.
④ Reasonably plan the operation time and frequency, and avoid rock drilling operations at night or during sensitive periods.
⑤ By rationally arranging the workplace, reduce the spread of noise in the space and reduce the impact on the surrounding environment.
⑥Train the staff to understand the hazards of noise and teach the correct use of mechanical equipment to reduce noise.
⑦ Use sound-absorbing materials inside the workplace to reduce noise reflection and resonance of noise and reduce noise levels.
⑧Regularly conduct noise monitoring to ensure that noise levels are within the legal limits and take control measures when necessary.
⑨Comply with local noise ordinances to ensure that prescribed limits are not overshot during rock drilling operations.
Conclusion
Reducing noise from rock drilling machinery cannot be ignored and has positive significance for workers’ health, the social environment, and ecological balance. By maintaining equipment, taking sound insulation measures, and rationally planning operations, etc., the generation and spread of noise from rock drilling machinery can be effectively reduced to protect the health of workers, reduce the adverse impact on the surrounding environment, and create a more friendly working environment for sustainable development.
