Australia’s mining industry adds about $60 billion to the country’s GDP. It is an important industry, both in terms of export revenue as well as OH&S issues.
More than most industrial activities, mining is constantly under close scrutiny from all angles over occupational health and safety matters. Although Australia is arguably a world leader in workplace safety for the mining industry, the sheer scale of the industry and its activities has its inherent dangers.
Mine ventilation is one such area, which calls for a number of significant work practices and technologies to be well developed so as to assure the safety of all mining employees.
Eximo has released a mine auxiliary ventilation system that is said to provide clean air for individuals and equipment as well as adequate ventilation for the removal or dilution of hazardous gases and dust.
Eximo’s general manager Melissa Phelps said that when designing a mine auxiliary ventilation system, the quantity of air required, physical restraints present, and other factors must all be considered, and taken into account.
“Air quantity must be considered in terms of both velocity and volume: the air velocity in the entry or tunnel; and the volume of air required for workers, the operation of diesel equipment, the dilution or removal of gasses and dust, cooling, and, or other needs.”
There are also physical constraints, which demand consideration.
These include: head room over haulage, or material transport equipment; length of duct, and associated handling and hanging problems; potential for damage from blasting, and other activities; the correct sizing of duct and fans to ensure that the fans are not working in a stall, i.e. attempting to move a volume of air greater than the duct’s capacity. A larger duct allows for a more efficient and lower horsepower system.
Other considerations include: the legal and contractual requirements for fans and duct, the preferred directional airflow: suction, or blowing; the acceptable levels of leakage for the determination of duct lengths; with most leakage occurring at the joints, longer lengths have significantly less leakage.
When evaluating the different types of duct available, there are four broad categories to consider: steel, fibreglass, flexible suction, and lay-flat.
Fibreglass, the most durable of suction ducting materials, is flame resistant, holds up well to abuse, is light-weight, gives high positive and negative pressure, has a low friction factor, and is best suited for: Short-length ventilation runs (less than 500 m.), multiple reuse operations, drill and shoot operations, and mine development.