The Chamber of Mines of Peru considers adequate ventilation systems as the main ally for safe work.
Fires and explosions are the main accidents that may occur in the development of mining operations, so the Chamber of Mines of Peru promotes their prevention.
In order to prevent and reduce these situations, extractive companies redouble their efforts to develop adequate ventilation systems. In this way, ventilation systems provide a healthy and adequate working atmosphere for the normal development of the production process.
Ventilation systems in underground operations must be designed with the purpose of ensuring the circulation of the necessary amount of air for correct breathing of workers, as well as the optimal internal combustion of diesel machines to avoid the formation of explosive mixtures. Also, to effectively dilute toxic gases, suspended dust and, finally, to reduce the temperature of electrical installations.
For the consultant of the Mining Chamber of Peru, Óscar Carrasco Pérez, “fire management and prevention represent a fairly high level of complexity, since in these situations, not only the areas affected by flames must be considered, but also the management of smoke and gases generated. The risk involved in fires is focused on the dimensions they can reach and the number of casualties that may occur among the workers involved.”
An example of what the specialist from the Chamber of Mines of Peru said occurred in January 2016. Four miners died after inhaling gases such as carbon dioxide, nitrogen and methane gas when an underground gallery of a platinum mine caught fire. The incident occurred in a mine owned by Impala Platimun Holdings, located in northwest South Africa.
In order to contribute to reduce the occurrence of this type of undesirable situations, the Chamber of Mines of Peru is constantly promoting training of workers, so that they know how to identify the potential causes of fires and the best way to prevent them.
Some of the causes of fire in mines are overheating of electrical equipment, as well as welding, which causes sparks on flammable materials, as well as the existence of combustible elements such as petroleum, oil, tires and others. Finally, another very common reason is t self-ignition of materials, a factor that depends on the granulometry of the substances, composition, porosity, humidity and storage size.
In this aspect, fire prevention in underground coal mines, which usually use more electrical equipment, requires a ventilation system capable of providing fresh air, as well as reducing heat and keeping methane gas levels below 5% of the lower ignition limit.
A particular characteristic of these deposits is that the element that causes the unwanted combustion of the coal can be quite dense, preventing the normal development of the works, even in remote galleries. A specific aspect in these cases is that if ventilation is considerably increased to disperse smoke, there is a risk of increasing the fire.
One of the most effective technologies for methane extraction in coal mines are reverse flow turbines since they can capture up to 100% of the extracted methane, and the heat produced from the extraction can be used locally for heating processes in very low temperature regions.
Another risk situation that occurs in mining operations is explosions. As an example of this situation, we can mention that in Colombia five workers lost their lives during the explosion that occurred in the Los Laureles coal mine. The accident occurred as a result of the accumulation of methane gas.
Among the measures that can be implemented for fire prevention in mines, we can mention that installation of several independent ventilation sectors must be foreseen in the deposits in order to limit the consequences of explosion or fire.
Each of these areas must have an independent air inlet duct that goes from a main ventilation duct and an independent air outlet duct to a main air outlet gallery.
The main ventilation of deposits must be ensured by means of one or more mechanical fans, installed on the surface and that operate constantly. The main fans must be constructed and located in such a way as to reduce the risk of damage in the event of an explosion and must be installed in closed fire-resistant enclosures. They should be powered by a power circuit separate and independent from the main mine circuit.
Special mechanical means such as secondary fans must be used in critical areas of the deposits. For example, one of the main causes of explosions in coal mines is the accumulation of firedamp. Therefore, to reduce this, it is necessary that the volume of air circulating in the area where this substance exists is sufficient to dilute it. Thus, its concentration is reduced to an insignificant or permissible value.
Installation of an artificial ventilation system is necessary to prevent fires and explosions in mines. A written or electronic record of methane gas (CH4) values must be kept and carbon monoxide (CO) must be monitored.
Finally, for each work site inside the mine, there should be two exits, that is, there should be a production shaft (entrance) and an emergency shaft (exit) for the evacuation of the deposit, which helps to increase ventilation, dissipating methane gas levels.
As can be seen, underground mining in Peru and Latin America has greater demands and to meet each one of them in a practical and adequate manner, mining companies require the contribution of specialized companies and the benefits provided by technological advances developed by these organizations.
For example, in Peru, ABB, the Swiss-Swedish company, has consolidated its position in the development of systems that allow the automation of ventilation, adjusting the air demand that may be required inside the deposit.
Thus, we can mention the SmartVentilation system, a solution for ventilation control that allows energy savings of up to 50% per year. It also ensures a healthy working environment, optimizes the dilution of hazardous substances and favors the rapid evacuation of explosive gases.
By way of conclusion, we can say that the optimization in the reduction and prevention of fires and explosions in mines must be based on the development of a planning system. It must have the capacity to dilute contaminating gases and reduce the concentration of those that can cause a possible self-ignition. In this way, a suitable working atmosphere is created to preserve the health of workers and the correct functioning of equipment.
