Prof. Dr. P. K. Jena
stone quarrying and crushing industries play a very significant role in the industrial and urban development programmes for construction of roads, buildings, sheds and other similar activities. These industries are generally located around industrial and urban areas to meet their growing demands of the construction materials. India has got good reserves of natural stones like granite, marble, sand stone, lime stone, slate etc. These are mainly concentrated in the states like Odisha, Andhra Pradesh, Rajasthan, Madhya Pradesh, Gujrat, Karnatak, Tamilnadu and Andaman Nicobar along with smaller deposits in other states. The stone quarrying involves drilling, blasting, cutting, surface grinding and polishing and the crushing units produce different size fractions. These industries particularly the crushers generate large quantities of particulate matters (dust). These particles pollute the air, water, land and vegetations at the sites and nearby areas considerably. For example, in a 200 to 600 tons per hour crusher, the fine particles generated range between 1000 to 3000 kg per hour and are liberated to the environment causing a lot of pollution problems for the land, water and air.
It has been estimated that, there are 12,000 stone crushers in India which provide direct employment to about 500,000 unskilled workers along with some skilled ones. In India, stone crushing industries have an annual turnover of about 5000 crores of rupees and hence it is economically an important sector.
Stone quarrying and crushing units have considerable impacts on polluting air, water and land and biological resources as well as socio economic settings of local population. The fine particulate matters generated during various quarrying and crushing operations result in considerable health hazards to the workers as well as surrounding population particularly by way of causing various types of respiratory diseases.
The particulate matters released in a large amount from the quarrying, crushing, screening and transporting activities also pollute the water. The alkalinities and hardness of both surface and ground water increase considerably due to the presence of carbonates and bicarbonates of mainly calcium and magnesium present in the dust particles. These fine particles pollute the air at the working places and the surrounding affecting the human beings, agricultural crops and livestocks. The respiratory disorders are caused in human beings as well as animals due to inhalation of the fine dusts. The workers are directly exposed to large concentration of dusts, noise and also are prone to accidents. Due to the dusts the people working there as well as those in nearby areas suffer from various respiratory, eye, skin diseases, and also fever, silicosis, dyspania, blood pressure problems. Silica dusts are also responsible for developing lung cancer, tuberculosis, and auto immune diseases. The noise causes sleeping disorder, depression, hearing loss, high blood pressure etc.
In our country there are many illegal stone quarrying and crushing units which operate in very unscientific manner causing a lot of harm to the workers as well as the people in the areas. They do not follow any rules and regulations for the safety of the workers as well as keeping the environment clean. In view of these, the state and central governments should enforce various environmental and safety measures both for the workers as well as the people living in the area.
In order to improve the working condition in the stone quarries and crushers, necessary precautions have to be taken.
At first, it is essential to stop releasing the fugitive dust emission from various activities of stone quarrying and crushing to avoid air, water and land pollution. The particulate emission from blasting, cutting and loading operations can be reduced by using water spray. The particulate matters emission is most during the process of crushing, screening at conveyor transfer point and storage facilities. The control for dust emissions include wet dust suppression, dry collection and combination of the two. The wet dust suppression is done by introducing moisture through water spraying into the material flow in a controlled manner to restrain fine particulate matters from becoming air borne. In case of dry process, at dust producing and exhausting emission points a collection device using suitable bag filters should be provided. However, provisions for both wet and dry suppression of the fine particles would be more effective. The wet suppression is normally used at the primary crushing stage and at subsequent screening, transfer points and crusher feeds. The dry suppression is used normally at points such as secondary and tertiary crushers discharge points, various designs for dust collection and the facilities are readily available in the country. Therefore, such practices should be adopted in all stone quarrying and crushing units so that the environment in the areas can be kept clean as far as possible. The crushers during operations should be enclosed as far as possible and the workers should operate the crushers, screening and allied operations from the outside of the enclosed area. At the same time, the workers should operate with all safety measures using helmets, safety shoes, eye glasses, mask etc., to avoid the dust as well as any accidents. The stone quarrying and crushing areas should be surrounded by a thick layers of trees. The workers should be familiar with all safety instructions so that they can apply those in case of emergency. The management should avoid child labour, which is very common in many illegal crushers. They should ensure provisions for clean drinking water and first aid, toilets, resting shades etc., for the workers. The owners of stone quarries and crushers, small or big, should practice all the safety measures for the workers and all these should be inspected time to time by the pollution control authorities in the area. All the fines obtained through wet and dry suppression measures should be properly collected and can be sold for various construction purposes or should be disposed in an isolated location in the quarry. Processes are available to suppress nearly 99% of the fine particles with the help of dry and wet processes.
Stone quarrying and crushing industries play a significant role for the development of roads and buildings in urban and industrial areas as well as other infrastructural facilities. These give employment opportunities for a large number of people particularly from rural areas. But the stone quarries and crushers being highly polluting, various safety and precautionary measures towards dust suppression, dust exposure and related accidents should be taken. All these units irrespective of their size should follow the rules and regulations prescribed by the state and Central Government, Pollution Control Boards. At the same time, the government should also develop an effective mechanism for proper implementation of various pollution control measures by the quarry and crushing units. Through their constant monitoring the sites and enforcing various pollution control and safety measures, the safety and health care of the workers and the environment of the locality can be effected. This will go a long way in meeting the requirements of the important construction materials and in keeping the workers as well as people in the neighboring areas happy and healthy.
(Former Director General, Council of Scientific & Industrial Research, India & Former, Planning Board Member, Government of Odisha)