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The effects of sulphur

By Ntsako Khosa

Mining poses a number of health and environmental issues. We consider the ramifications of sulphur.

Although sulphur plays an important role in the upkeep of life on earth, too much of it can have damaging effects on human, animal and plant life. Sulphuric acid has become an integral part of the mining industry — today, sulphuric plants are operating more extensively in the mining industry than in the chemical industry in South Africa.

Sulphur is a non-metallic element, a valuable commodity, and an integral component of the world economy. It is used to manufacture numerous products, including fertilizers, chemicals, paints, rubber products, medicines, fibres, sugar, detergents, plastics, paper and many other products. Sulphur is also a vital nutrient for crops, animals and people.

Sulphur and mining

Acid mine water is caused by the outflow of acidic, metal-rich water formed by the reaction between the water and rock containing sulphur-bearing minerals in mine sites. It especially occurs in metal and coal operations, and often the affected water supplies end up developing acid levels similar to those of battery acid. This makes the water harmful to humans, as well as animal and plant life.

Coal remains the number one mineral largely used to supply energy to the country and other parts of the African continent. The International Energy Agency (IEA) reported that coal is the fastest growing global energy source of the 21st century, ensuring 40 per cent of the world’s electricity supply in 2014.

After coal is mined, it goes through processing before it can be used in industrial processes. Processing removes the non-combustible contaminants in the as-mined coal, which increases the effective energy content of the coal. This also lowers the sulphur content of the coal, reducing the emission of sulphur compounds when the coal is burned. Coal contains sulphur naturally, and when coal is burned, the sulphur combines with oxygen to form sulphur dioxide.Energy production through coal releases sulphur dioxide, nitrogen dioxide and particulate matter (PM) at levels that exceed the maximum recommended by the World Health Organization. Coal-fired power plants are the largest human-caused source of sulphur dioxide. The element is a contributor to the production of acid rain and causes significant health problems.

Environmental and health impacts

Mpumalanga is home to 12 of the 16 coal-fired power plants in South Africa. The area is struggling with the devastating impacts of more than a century of excessive mining. In 2007, government declared the area as high priority due to the hazardous substances in the air. Scientists found elevated carbon dioxide emissions, sulphur dioxide in the air, heavy metals in the soil, and acidic groundwater. “The pH levels around here are below one. Some residents of the informal settlements say that birds fall dead from the sky when they fly over the area,” says Matthews Hlabane from the Southern African Green Revolutionary Council. Water with a pH lower than seven is considered acidic, and a pH greater than seven is considered basic. Hlabane states that the Olifants River is contaminated and the same is going to happen to the Limpopo River, which sits close to the Waterberg mining operations.

Due to the limited possibility of destruction of the sulphur bonds applied, it can be found in the air in varying degrees. Damaging effects of sulphur to animals are mostly brain damage and damage to the nervous system. Continual exposure to the gas over an extended period can permanently alter the natural variety of plants and animals in an ecosystem.

Laboratory tests with test animals have indicated that sulphur can cause serious vascular damage in the veins of the brain, the heart and the kidneys. These tests have also indicated that certain forms of sulphur can cause foetal damage and congenital effects. Mothers can even carry sulphur poisoning over to their children through breastfeeding. Sulphur can damage the internal enzyme systems of animals. It can also cause irritation of animals’ eyes and throats when the uptake takes place through the inhalation of sulphur in the gaseous phase.

Sulphur dioxide is a moderate to strong irritant of the respiratory system. Effects of exposure can be short or long term.

Globally, sulphuric substances can have the following effects on human health:

  • Neurological effects and behavioural changes
  • Disturbance of blood circulation
  • Damage to the heart
  • Effects on eyes and eyesight
  • Reproductive failure
  • Damage to immune systems
  • Stomach and gastrointestinal disorder
  • Damage to liver and kidney functions
  • Hearing defects
  • Disturbance of the hormonal metabolism
  • Dermatological effects
  • Suffocation and lung embolism.

Source: lenntech.com

Regulating mine pollution

In South Africa, we have the National Environmental Management Act, also known as the NEMA Act, which regulates the protection of all environmental resources, including water. Section 24N (3)(b) requires that the environmental management programme must contain measures regulating responsibilities for any environmental damage, pollution, pumping and treatment of extraneous water or ecological degradation as a result of prospecting or mining operations or related mining activities, which may occur inside and outside the boundaries of the prospecting area or mining area in question. This provision requires mines to address and plan for the management of acid mine drainage (and other environmental impacts). Failure to abide may lead to the non-issue of environmental authorisation.

Phuti Mabelebele from the Department of Mineral Resources, which regulates the duties of mining companies to prevent environmental damage, says that currently 263 mining licences and more than 500 prospecting rights have been granted.

Legislation and regulations by government are steps in ensuring the continued safety of citizens and the environment at large. According to a study by CJ Badenhorst that was published in 2007, occupational exposures to airborne sulphur dioxide are evaluated against occupational exposure limits (OEL). OELs are prescribed in the Hazardous Chemical Substances Regulations (1995) of the Occupational Health and Safety Act, 1993 (Act No. 85 of 1993) and Schedule 22.9(2)(a) of the regulations of the Mine Health and Safety Act, 1996 (Act No. 29 of 1996). One of the fundamental requirements of the law is the prevention of employees’ exposure to substances hazardous to their health.

Badenhorst suggests that excessive sulphur dioxide exposure should be prevented by elimination at the source, that is, by means of ventilation extraction systems, including at-source extraction hoods. “To prevent the reintroduction of extracted sulphur dioxide into the workplace air, such extraction systems should be fitted with exhaust air filtering devices, preferably electrostatic precipitators. The design of any sulphur dioxide extraction system should be as such that emissions are removed at source, at a capture velocity of at least 0.75m/s,” he advises. He further suggests the use of respiratory protective equipment (RPE) if engineering control measures fail to provide the required control of an inhalation hazard. “RPE must meet governmental requirements. Programmes for the care and maintenance of RPE are critical to continued effectiveness,” he adds.

Sulphur dioxide is often seen by industry as nothing more than a health and, to a lesser extent, safety irritant associated with the generation and handling of sulphur dioxide and the manufacturing of sulphuric acid. The toxicological properties of sulphur dioxide are either misunderstood or ignored by employers. This can be fatal. Whenever a possibility of excessive exposure exists, appropriate control and management programmes must be put in place.


Whenever a possibility of excessive exposure exists, appropriate control and management programmes must be put in place.


 

An occupational exposure level refers to the time weighted average airborne concentration of a chemical substance for a 40-hour work week, and represents conditions under which it is believed that nearly all workers may be repeatedly exposed without adverse health effects.

independentecon.co.za

 

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