In a productive and highly competitive business environment like the current one, resource optimization and maximizing the utilization of materials extracted from the Earth are critical for the development of products and technologies. That’s why the extractive industries of mineral resources must strive to be more efficient and minimize the risks associated with their activities. In particular, underground mining requires adequate ventilation to ensure the safety and well-being of workers underground. In this regard, cooling systems in the mining industry play a fundamental role in meeting the necessary standards and regulations to create a healthy and safe environment.
Cooling in the mining industry: a complex context
In summary, mining is an economic activity that belongs to the primary sector, focused on the extraction of minerals and commercially viable elements from the Earth’s crust. This activity is carried out through two main methods: open-pit mining and underground mining.
Focusing on underground mining, it involves penetrating the rock into the subsurface to create galleries and tunnels leading to the deposits. This form of mining requires the establishment of a healthy and safe environment for workers, which is achieved through air conditioning and cooling systems.
Clearly, cooling in the mining industry faces a complex context due to the challenges involved in maintaining a suitable environment underground. Occupational accidents caused by deficiencies in ventilation or circumstances derived from them are latent risks in these environments. Therefore, cooling is a critical aspect for operating companies in the course of their daily work.
In general, ventilation in an underground mine aims to supply a sufficient amount of air to all workstations and galleries. It also aims to reduce contaminant levels that cannot be controlled by other means to an acceptable level. This involves establishing a circuit for air circulation throughout all operations, which is possible by creating two separate access routes such as shafts, tunnels, or combinations thereof. In cases where there is only one access route (e.g., an advancing gallery), secondary ventilation is used through the use of pipes.
Why is ventilation necessary in underground mines?
Adequate ventilation in an underground mine is essential for several reasons:
- Firstly, it is necessary to ensure a minimum oxygen content in the atmosphere to allow for the breathing of people working inside.
- On the other hand, it is essential to dilute toxic, asphyxiating, and/or explosive gases below the permissible limit values established in each country.
- It is also necessary to climatize the mine since the temperature increases with depth. Additionally, the equipment and machinery present inside contribute to further raising the air temperature.
- Lastly, it is crucial for cooling in the mining industry to provide thermal comfort in the work areas so that workers can operate under optimal conditions, ensuring higher performance and safety.
The composition of the atmosphere in a mine varies slightly in different locations, and its control is essential to maintain a safe environment. Likewise, ventilation must control contaminants such as gases and dust, as well as ionizing radiation associated with natural radon in uranium mines. The amount of air required for dilution control depends on the strength of the contaminant source and the effectiveness of other control measures. It is important to consider the additive or synergistic effect of contaminants and establish a minimum air flow to ensure safety. Typically, the standard is at least 0.25 m/s and increases with the air temperature.
How do cooling systems work in the mining industry?
While many mines use fan systems to ensure suitable temperatures and air quality inside, cooling systems are increasingly being chosen. To such an extent that the most commonly used cooling systems in the mining industry today are vapor compression systems. These systems consist of compressors that generate the necessary cooling. The capacity of these plants can range from 5 MWR (megawatts of refrigeration) to over 100 MWR. They can be designed as centrifugal or positive displacement screw compressors. Ammonia is often used as the refrigerant on the surface and a suitable halocarbon underground.
Similarly, the heat required for condensing the refrigerant after compression is expelled into the atmosphere. The purpose of this is to minimize the energy required to provide cooling to the mine. Wet heat rejection systems are used for this purpose, where the refrigerant condenses in shell and tube heat exchangers or plate and frame heat exchangers using water. Then, the extracted heat is expelled through cooling towers.
After condensing the refrigerant through an expansion valve, the evaporation takes place in another heat exchanger. There, the liquid and gas mixture is cooled to a low temperature to generate chilled water. This chilled water serves a dual purpose: cooling the incoming air and supplying cold water to the mine. However, it is important to note that constant contact between water, ventilation air, and the mining environment can affect water quality and lead to dirt accumulation in the heat exchanger. This phenomenon increases the resistance to heat flow and can affect the system’s performance.
For this reason, it is advisable to select equipment with ample surface areas in contact with water and that are easy to clean to minimize this undesired effect. Spray chambers and cooling towers are used both on the surface and underground. These components facilitate more effective heat exchange between the cooling air and the water involved in the cooling process.
Intersam takes on cooling projects in the mining industry
Intersam has over 25 years of experience in the design and development of industrial and commercial refrigeration and air conditioning systems. Since 1995, it has established itself as a leader in the sector, standing out for its commitment to quality, innovation, and energy efficiency.
Throughout its trajectory, Intersam has undertaken large-scale projects both in and outside of Spain. In all of them, it has demonstrated its ability to tackle technical challenges and adapt to different environments and needs. An emblematic example is its involvement in the transition of the Chuquicamata Mine in Antofagasta, Chile, into an underground mine. In this project, Intersam played a fundamental role by supplying and installing powerful vapor condensing units that ensured efficient cooling in mining operations. The design and implementation of these systems help maintain optimal conditions in terms of temperature and humidity, which are crucial for safety and performance in mining environments.
Intersam’s successful participation in the Chuquicamata Mine is just one example of its ability to address challenging and highly complex projects. Its proven experience, combined with its commitment to quality and innovation, makes it a reliable and secure choice for companies seeking efficient and tailored solutions in the field of cooling in the mining industry.