Raw-material for mineral based industries and power plants need to be properly managed
By Prof P.K. Jena
Mineral resources of the world has been the key raw materials for most of the major industries. Coal and other fossils fuels are used in generating thermal energy. Water is used for producing hydro-power and the nuclear metals like Uranium is used to produce nuclear power. All these industries require the three main raw materials mainly minerals, water and energy. In recent decades, due to rapid increase in population particularly in developing countries like India and establishment of various types of industries, the demand for minerals, energy and water is increasing at a very fast rate. In view of this, in recent years, a lot of scarcity of the raw materials for our mineral based industries and power plants is being experienced. The metallurgical industries are hungry for proper grade of ores and minerals as well as for energy and water resources. Similarly, the thermal power plants are facing a lot of problems in obtaining good grade coal.
In recent years, due to non availability of good grade iron ore and non coking coal, a large number of sponge iron units in the eastern region of India have reduce their production considerably. Due to want of bauxite, leading aluminium producer like Vedanta Aluminum Ltd., at Lanjigarh, Odisha is reported to be closed down. Similarly, most of the mineral base industries are facing acute shortage of water for which they are forced to cut down their production and this is the case particularly in the state of Odisha. The surface water resources are considered to be earmarked for domestic and agricultural purposes. When the industries are drawing a large amount of such fresh water particularly from the rivers, these are facing a lot of resistance from the local people particularly from the farmers. In addition to these problems, most of the industries are found to be very casual in proper disposal of their wastes and effluents. As a result of these, the nearby land, water and air are getting polluted and causing inconvenience to the local people. Due to limited knowledge about the advantages of the production of nuclear energy, there is found to be a lot of public resistance when a nuclear power plant is proposed to be set up in a locality. Thus, the adverse effects of industrial pollutants and apprehension for further hazardous situation are adding more problems to the dearth of raw materials for smooth running of the metallurgical and power industries.
In this paper, the present situation regarding the mismanagement of principal raw materials has been described and discussed. An attempt has been made to suggest some remedial measures for better management of mineral based industries and power plants.
Mineral Resources as Raw-material Minerals are the most important raw materials for the mineral based industries as well as thermal and nuclear power plants. Key industries like production of metals and alloys, refractories, inorganic chemicals & fertilizers, thermal and nuclear power plants are mineral based. During a few decades of industrial development, most of our high grade mineral resources have been mined extensively for internal consumption and export. In this way most of the high grade minerals have been exhausted. As these resources are nonreplensible in nature, it has been necessary to conserve these valuable natural resources and develop various technologies to process the low grade and complex ores and minerals to sustain the existing industries in the country.
The unscientific mining by most of the mine owners has resulted in loss of large amounts of good grade ores in form of fines. The craze for earning quick money and faulty mineral policy of the government are driving the mine owners to adopt various unfair means to export large amounts of good grade minerals and leaving behind the low grade ones in the mine to be diluted with the over burden. In many mineral based industries, the out dated technology is being utilized to process the ores and minerals to produce the suitable grade raw materials for metallurgical and thermal power plants, resulting in the loss of large amounts of mineral values as wastes. Further, during grinding of the minerals for beneficiation and producing the metals and alloys, a lot of energy is consumed because of out dated technology and inefficient operational procedures. In many mineral based industries particularly during washing and beneficiation of the ores and minerals, a lot of water is used and released with least care for recovering and recycling the used water.
Water Harvesting and Recycling All the above mentioned mineral beneficiation processes require a lot of water. As the water scarcity for industrial purposes has already been felt, it is essential to have their water resource by harvesting rain water and recovering and recycling the water used in the beneficiation processes. The mineral industries should consider adopting new technologies to recover the waste water from the beneficiation process and recycle the same. For recovering the used water, the processes which can be adopted include sedimentation, filtration and centrifuge. Various technology and equipments used in this processes are already available in the country.
Recovery of values from Tailings The tailings and washery slimes of various mineral beneficiation units have still a lot of mineral values. These values should be recovered wherever possible.
In India, the major ore beneficiation activities are in the iron sector. After beneficiation of iron ore, the tailings which are being disposed in most of the iron ore beneficiation plants contain about 45% or more iron. From both the environmental and mineral conservation points of view, it has become worth while to process the iron ore beneficiation tailings to recover the iron values.
Industrial Wastes as Raw Materials Mineral processing and metallurgical industries generate huge quantities of solid wastes as well as liquid and gasses effluents. These wastes contain appreciable amounts of metal values. In order to conserve and judiciously utilized the mineral resources and also to protect the environment from the toxic effects of some metals present in the wastes, it is essential to recover the metal values from the solid wastes and effluents and utilized those as raw materials for metallurgical industries. Some of the important wastes like bayer’s sludge, tin smelter’s slag, copper converter and smelter slags, copper converter flue dust, electric arc furnace dust, effluents of electroplating industries spent catalysts and the scraps rejects should be treated to recover the metal values. Fortunately these wastes contain many high valued non-ferrous metals like vanadium, niobium, tantalum, copper, nickel, cobalt, zinc, lead etc.
Water Resources as Raw-material India and most of the other developing countries are the worst suffers of fresh water crisis mainly because of wrong planning to manage their fresh water resources both on the surface and in the ground.
To harvest rain water both on surface as well as recharging to the ground.
(i) Processing the waste water and recycling the same in the industries.
(ii) Economizing the use of water in various mineral processing and metallurgical industries and thermal power plants.
In area of metallurgical industries, the mineral processing needs largest amount of water for washing and beneficiation. Therefore, the mineral processing industries should be situated near the mines so that the rain water harvested in the mine pits can be suitably utilized. In India, there are nearly 3000 mines extracting annually about 700 Milion Tones of minerals. The water holding capacity of fresh mine pits created every year has been estimated to be around 350 Million Cubic litres. It has been estimated that, the rain water harvesting in the old as well as newly created mine pits in India every year can meet the domestic requirements of about 30 million people. This huge quantity of water can be utilized for mineral processing as well as keeping the environment of the mining and mineral processing industries clean.
In view of the shortage of water, the Ministry of Environment of Forest (MoEF) Govt. of India, has laid down some specific norms for mineral based industries to treat and recycle the effluents and harvest rain water to meet most of their water requirements. Therefore, it is essential to conserve and recycle the water through the dewatering processes in the mineral processing units. In this regard, various technologies have been developed to recover the waste water from the beneficiated minerals. Some of the important processes to recover the water include sedimentation, filtration and centrifuge.
In addition to mineral beneficiation, a lot of water is also used in metallurgical industries like integrated steel plant, alumina production and aluminium smelter. At present in most of the integrated steel plants a lot of used water for coke ovens, sintering plants, Blast furnace, steel making operation etc are being treated suitably and recycled.
Recently, Jena has suggested some remedial measures towards integrated development and conservation of the water resources. Some of his suggestions are given below:
1) Rain water harvesting on surface as well as charging to aquifers should be carried out in a scientific manner without any contamination.
2) Adoption of efficient irrigation system like sprinkle and drip irrigation and encouraging farmers for producing crops, which consume less water.
3) Loss in water transport to be minimized by adopting improved technology.
4) Treatment of sewage, industrial effluents etc. before discharging the treated water to the main water bodies, has to be practiced.
5) Programmes for development of wet lands and creation of new water reserves to harvest more rain water and recharging aquifers along with developing aquatic wealth have to be undertaken.
6) Industrial should have captive rain water harvesting programmes to meet their water requirements and also should recycle the waste water.
7) Measures to minimize the use of chemical fertilizers and pesticides in agricultural fields, instead using organic manures and organic pesticides have to be undertaken.
8) Pricing of water has to be done in a rational manner.
9) Arrangements have to be made to provide portable water to all and
10) Regular monitoring of water quality (both surface and ground) needs to be carried out both in rural and urban areas.
Energy Resources as Raw-material The mineral and metallurgical industries require a large amount of energy particular the industries like aluminium smelter. Some of these energy intensive industries have their own thermal power plants. In many cases due to the short supply of proper grade of coal these power plants produce much less energy compared to their full capacity. In such cases, they should have alternate arrangements like energy from hydro power or nuclear power in order to maintain their productivity. Most of the industries for their offices and colonies should use renewable sources of power like solar energy, solar cells or wind mills.
Conclusion Minerals are major natural resources for development of most of the key industries like Thermal Power Plants, Integrated Iron and Steel plants, Aluminium Copper, Nickel and other non-ferrous metals production units etc. To make these industries sustainable, it is essential to conserve and judiciously utilized the mineral resources which are non replenisible in nature. In this process, it is necessary to scientifically mine all grades of ores and minerals, beneficiate the low grade ones, agglomerate the ore fines and concentrates, extract most of the metal values adopting environment friendly technology generating minimum amount of wastes and recovering the values from the wastes. While managing the minerals, it is also necessary to properly manage the other two raw materials namely water and energy. Like minerals, the water and energy are highly valuable and limited in quantity. Therefore, these have to be equally conserved and managed properly. It is suggested that, both on surface and in the ground the rain water has to be harvested and at the same time the used water has to be treated and recycled, so that minimum amount of fresh water from sources like river should be taken. In the energy sector, as the coal based thermal power is getting more and more scarce because of non-availability of required amount of good grade coal, efforts should be made to utilized energy from hydro and nuclear power plants. Each and every metallurgical industry should have captive power plants so that these industries can be independent of general power supply. In addition to this, mineral based industries should also utilized the non conventional sources of energy like solar energy and wind mills for meeting the energy requirements for their offices, colonies etc. In this way, the mineral based industries can be sustainable if the major raw materials like minerals, water and energy are properly managed and conserved.
The above is an abstract of the Presidential Address of Prof PK Jena at the International Symposium on Management of Raw Materials for Metallurgical and Power Industries (MRMMPI – 2013) held between 9 to 11, January 2013 at Bhubaneswar. Currently, Prof Jena is the Chairman, Institute of Advance Technology & Environmental Studies (IATES), Bhubaneswar. He was the former Director General of CSIR, New Delhi.