Mining is among the most popular significant activities that contribute to the economic growth in India. A totality of the small-scale mining units contributes up to 6 percent of the mining industry in the nation. However, with apart from being a major contributor in the economic growth and development, the mining industry is also a leading contributor in the air pollution levels of the country. Various fugitives that are accounted and unaccounted for are suspended in the air making it unfit for breathing and often harmful in nearby areas. The pollution caused by the mining industry can lead to serious, long term and chronic respiratory problem for humans and animals. It can also hinder in the plant growth process of areas in and around the site.
Understanding the mining process:
There are various stages in the mining process which add to the total emissions and air pollution. Stages in the mining process such as blasting, unpaved roads and dust explosions during loading all cumulatively add up to the fine particulate matter of coal dust, heavy metal dust and harmful gasses such as carbon monoxide, carbon di oxide and nitrogen dioxide.
- Excavation: this step is the first and foremost stage in the mining process where a mine is opened up. Sub steps such as drilling and blasting are heavily relied on to get the location ready.
- Pre- processing: this refers to a step where ore is stockpiled from underground open pit mines and is fed into the primary crusher at the process plant. This crushed rock is then transported to the mill.
- Transportation: this refers to a sub set where the ore is transported for processing either to an on-site or off-site plant. This is generally placed between the extraction site and the processing plant.
- Main processing: this refers to a step where milling, grinding and smelting takes place to process the metals more and make it suitable for sale
- Refining: this refers to a step where all advanced process is practiced such as electro and hydrometallurgy for getting the desired results of highly pure and refined ore.
What are fugitive emissions?
Fugitive emissions simply refer to the generation of air pollutants cause by industrial processes. It is extremely difficult to monitor fugitive emissions as they are generally not accounted for. Hence, it becomes very difficult to identify the source and reduce the cause of the pollution.
Air pollution caused by mining activities:
Most steps in the mining process result in heavy emissions of air borne pollutants such as exploration, development and construction. The waste piles that are generally created by the mining process can lead to a diffusion of small size particles by winds.
During the steps of blasting and excavations heavy winds blow which cause a spread of air pollution due to the open- pit setup. The heavy vehicles that are used for transportation and equipment’s used to complete the steps are also major contributors to the air pollution and increase particulate matter emissions. Various gaseous emissions that are generated in the mining cycle can be identified as fugitive emissions. The microbial and anaerobic wastes generated due to waste degradation also produce different gases that cannot be accounted for.
Combustion from the fuels of equipment’s for the mining process also adds up to the gas emissions that are released from the mining site.
- Stationary sources of air pollution: This refers to gaseous emissions from the combustion of fuels that are used in the process of instillation, drying, roasting and smelting. Most of the times, the ore which is found is melted on-site before being transported to off-site refinery plants. Fluxing furnaces that are commonly used for producing gold and silver also produce high levels of air borne sulfur di oxide and mercury that may be harmful to the environment.
- Mobile sources of air pollution: This refers to the pollution caused by heavy vehicles that are used I the process of evacuation, vehicles used to transport personnel to and from the mining site etc. the levels of pollution caused from these sources is directly dependent on the fuels and equipment conditions that are being used. The individual use of these emissions may not be of concern but when all the pollution levels are put together the levels may often be alarming.
The pollutions caused by the mining process can cause chronic health issues to the people working on the sites and living in nearby areas. Black lungs are the most commonly found health hazard that is faced in the mining industry that happens due to a constant and continuous inhalation of the mining dust. Apart from this, the mining emissions can also cause respiratory complications such as silicosis, lung cancer and asbestosis.
Mining industries also face a complication by the government that charges heavy regulatory fines if the pollution levels surpass the regulations set. High levels of air pollution also reduce the productivity and can lead to high labor absenteeism due to sick leaves. Extensive mining activities can also lead to disharmonies with people living in nearby areas due to degradation of the environment. Union strikes and labor demands should also be well managed and dealt with appropriately.
Fugitive emissions cannot be captured easily by the existing air pollution control systems. The mining process involves both indoor as well as outdoor air pollution emissions. The systems installed must be able to capture and control dust emissions n large areas and not just short small spans on land. A large structure should be dealt with at a single time to ensure that the dust and pollution does not spread and is controlled at the time of generation itself. The most commonly used modes of controlling air pollution is scrubbers, electrostatic precipitators and bag house filters that all work together to form a combination of extensive pollution control.
Certain technologies cater to specific pollutants in the specific stages of the mining process but may not help in pollution control for the entire mining process as a whole.