How can we conserve and scientifically manage mineral resources for sustainable development
Minerals are one of the most important natural resources. They are mined and used to meet our growing needs for energy, metals and alloys, cement, refractories, pigments, inorganic chemicals and many more. The socio-economic developments of today’s world have been possible mainly because of this resource.
However, being non-renewable in nature, the minerals are used on a large scale and are depleting very rapidly over the past few decades. It is feared that unless effective measures are taken to conserve and wisely use all the qualities of this resource, our industrial and socio-economic progress will slow down very significantly. Do
sustainable development, it is necessary to properly manage mineral resources using environmentally friendly technologies with a zero waste approach.
Industries in the areas of thermal and nuclear power generation, iron and other metals and their alloys, specialty materials, cement, inorganic chemicals and refractories are all mineral-based. Over the past half century or so, extensive mining of minerals and the upgrading of weak and complex minerals has taken place in the mining areas, disturbing the earth’s crust, destroying much of the vegetation and polluting the earth, water bodies and air to a large extent. .
In addition, during the use of minerals in the thermal, metallurgical, chemical, cement and refractory industries, enormous quantities of solid waste and liquid and gaseous effluents are generated. Large quantities of wastes and effluents such as tailings and washing sludge produced during the beneficiation of low-grade coal, iron ores, manganese,
copper, etc., fly ash produced during thermal power generation, red mud generated during the production of alumina from bauxite, and slag and leached tailings produced during metal mining affect human settlements, vegetation and water bodies and also create a lot of environmental problems. problems.
For example, nearly 1 ton (T) of fly ash2 for 2.5 T of coal consumed in thermal power plants, and about 2.5 T of red mud to produce 1 T of aluminum from bauxite and about 200 T of residues in the production of one ton of copper from its ore, are generated and dumped on land and in water bodies, creating great environmental pollution and destroying land, forests and water resources.
Major mineral-based industrial wastes such as slag, red mud, fly ash, sludge and tailings from mineral processing units pose huge environmental problems globally. In recent years, due to the application of various environmental rules and regulations and also due to the need to conserve the limited mineral resources, it has been somewhat mandatory to develop technically-economically viable processes to treat industrial waste and convert them into resources.
To use vital non-renewable mineral resources wisely, with a zero waste approach, it is essential to take the following steps for their conservation and wise use.
(a) Adopt scientific mining practices to exploit all grades of minerals
(b) Valuation of lean and complex minerals
c) Agglomeration of mineral fines and mineral concentrates after upgrading
d) Recovery of waste from thermal power plants
e) Use of waste from metal extraction plants and other industrial and domestic metals
Adoption of science-based mining practices to exploit all grades of minerals
Mineral extraction must be planned in a very scientific and integrated way so that the different grades of minerals are extracted as selectively as possible without damaging other resources such as water and forest. Modern mining technology must be adopted to obtain as much as possible of the mineral resources present in the mines.
low quality minerals as well as lesser minerals available with major minerals, which cannot be
economically extracted today, must be stored properly so that they can be used later when the processes become economically viable.
Valuation of lean and complex minerals
Reserves of high-grade minerals are much lower than those of medium- and low-grade minerals. Also, in some cases, more than one metal is present in the mineral body in appreciable quantities that must be processed and recovered.
While using high quality minerals as such, leaner ones have to be appropriately mixed with high quality ones or have to be improved by various physico-chemical processes for their further use in metallurgical, thermal, refractory and other industries. chemicals. In recent years, various beneficiation techniques have been developed and used to beneficiate low-grade coal, iron ore, chromite, manganese ore, etc.
Agglomeration of mineral fines and mineral concentrates after upgrading
Large quantities of mineral fines are generated and accumulate at mine sites, primarily due to mechanized mining. In addition to this, the brittle nature of some minerals like chromite also results in a high percentage of fines during mining.
In addition, the low and mid-grade minerals that make up a major fraction of the reserves need to be upgraded, resulting in a lot of fine concentrates. A substantial amount of ultra-fine mineral concentrates can also be recovered from the mineral wash sludge. All these fines of various origins must be agglomerated before being used in the metallurgical and refractory industries. These must be agglomerated either by sintering, pelletizing or briquetting. Of these three agglomeration processes, sintering is considered the most economical.
For example, most iron ore fines are sintered to be charged to the blast furnace with the lumpy ores or as is to produce iron. Sintered materials are considered better raw materials from the point of view of reduction kinetics.
Recovery of waste from thermal power plants
Throughout the world, the thermal power plant is the only major generator of electricity representing about 55% of the total electrical energy generated. Extensive research and development in different parts of the world has been undertaken in recent years to utilize most of the fly ash generated as waste in coal-fired power plants. Fly ash can be used to produce cement, bricks, building blocks, agglomerates, good quality concrete mixes, fill mining voids and low areas, develop embankments and also improve soil fertility. It is reported that in developed countries most fly ash is used in this way, but in India only 20-30 pct. ash generated is currently used and the rest is dumped into ash ponds or as an ash heap.
Clay – fly ash bricks, calcium silicate fly ash bricks, aerated concrete, small amounts of fly ash in the manufacture of cement, fly ash lime – gypsum bricks (FaL-G), sintered lightweight aggregates 4, etc. ., are some of the potential elements that can be used in building and road construction activities and thus consume considerable amounts of fly ash.
Use of waste from metal mining plants as well as other industries and domestic waste
In metal extraction processes, many wastes such as slag, combustion dust, leached residues, sludge, etc. containing many mineral values are generated. These must be processed to recover the metal values. In addition to this, rejected metals containing items from other industries as well as domestic sectors should be collected and the metals should be
recovered by various suitable methods.
Mineral resources are very essential for the socio-economic development of human society. Most of the current practices of unscientific mining of minerals and their subsequent use in various sectors have resulted in the loss of appreciable amounts of mineral values. To support our economic development, we must apply the best available environmentally friendly technology to mine minerals as well as use them for various purposes with a zero waste approach. Some of the measures to be taken in this regard are:
- Constant efforts must be made to locate new reserves of mineral resources in the earth’s crust and use advanced technologies to exploit them to the maximum with minimum damage to other resources such as water bodies and forests.
- All grades of minerals need to be mined and the low grade ones need to be upgraded to make them suitable for further use in various mineral-based industries.
- Advanced environment-friendly technologies should be applied for the utilization of these resources, either to generate energy, or to extract the metal values, or to produce other mineral-based products with a zero-waste approach. .
- Various efforts should be made not only to utilize the waste but also to minimize its generation and recycle the waste with or without pre-treatment whenever possible.
- Efforts should be made to recover metal values from secondary sources such as spent catalyst, scrap, e-waste, etc.
- In the process of using mineral resources for our socio-economic benefits, we must avoid environmental pollution and maintain an environmentally friendly atmosphere.