With the growing production, the demand for mining equipment and machinery is expected to not just keep pace but grow manifold. The thrust on surface mines has significantly enhanced mine production capacity through the infusion of millions of rupees in the large capacity mining machinery and material handling system, writes GK Pradhan.
 
India has emerged as one of the major mineral producers globally. This was achieved due to the burgeoning demand for raw materials being mined for sectors like power, steel, fertiliser, atomic energy, etc. (The index of mineral production for the last few years is placed in Table 1). The increase in metallic minerals is primarily due to the increase in export of iron ore and domestic consumption hike of iron ore. Similarly, since 2004-05, the hike in non-metallic minerals due to expansion of cement plants and rise in production of Pb-Zinc from mines of Hindustan Zinc. Growth in fuel minerals, though, is not substantial despite increase in demand for coal and lignite for power plants under expansion and commissioning. In turn, import of coal for steel and power plants have increased manifold.

Coal Mining

Coal mining in India has laid much emphasis on surface mining, together with huge investments by Coal India in some of the mega projects. While underground production is stagnating, production from surface mines are on a rise (Table 2). The thrust on surface mines has also significantly enhanced the mine production capacity through infusion of millions of rupees in large capacity mining machinery and material handling system.

In order to extract some inaccessible coal deposits, a number of new initiatives have been taken in the last few years. In the mines of Coal India and Singareni Collieries, high wall mining has been adopted.

Asia's first and also of India, high wall mining system has started operations at opencast Project-2 (OCP-2), Rama?gundam Area-III (RG-III) of Singareni Collieries Company. (SCCL) from 10 December 2010. It is being operated by Advanced Mining Technology, Hyder?abad, using the machine manufactured by ADDCAR Highwall Mining System, USA. The machine started extraction of the locked up coal seams beneath the open pit high wall under CIMFR guidance and monitoring.

On 5 March 2011, at the Sarda Project of South Eastern Coalfields (SECL), high wall mining was successfully commissioned. By the high wall mining method, this mine is expected to produce 6.0 million tonne of coal in nine years. SECL had outsourced the entire production system to Cuprum Bagrodia, on cost per tonne basis. They have deployed one set of the high wall system of superior high wall miners. The results so far achieved indicate that this system will be a profitable venture and will help Coal India extract some of the coal seams hitherto not economically viable to produce. This technique has also been also selected for Medapalli Opencast Project, RG-I Area of Singareni Collieries Company. (SCCL) and Quarry (SEB and AB), West Bokaro of Tata Steel, and other coal mines also. Apart from very high coal recovery, this system had several operational and safety related benefits.

In order to augment the increase in coal production from the mega coal mines of Singrauli Coalfields under Northern Coalfields, and also in the upcoming coal mines of Reliance Power, large capacity draglines, electric shovels, drills and other support equipment are under commissioning. Reliance Power at their captive coal mines of Singrauli, from the Moher-Amroli extension and Chhatrasal coal mine blocks in the Singrauli coalfields allocated to Sasan Power Limited, having aggregate coal reserves of around 700 mt, will produce 25 mtpa.

Surface Miner

Another innovative mining method introduced successfully in India has been the use of surface miners in coal and limestone mines. After its success in the Lakhanpur Coal mines of Mahanadi Coalfields in the late 80s, today all coal mines and limestone mines together have more than 250 surface miners in operation. In 1994, a Wirtgen surface miner 1900 SM demo machine started tests in Ambuja Cement's Gujarat operations. This machine proved the ability of mining and sizing the soft limestone without blasting. These have not only abolished blasting operations, but also resulted in production of high cost, sized coal of high calorific values. This success led Coal India to look more closely at this technology. Wirtgen was faced with the situation of blocked coal in the Mahanadi Coalfield. More than 7 million tonne of coal were situated close to a village and could not be mined because of blasting restrictions. Mahanadi Coal Ltd, together with Wirtgen, developed a project to mine this coal using surface miners. This first success story led to continuing projects, with increasing amounts of coal to be mined.

The application of surface miner technology leads to extracting medium hard minerals by taking advantage of the higher efficiency of continuous excavating. Extracting of 'run of mine' product in one step, which makes at least the primary crushing stage dispensable, eliminates the hazards of blasting and environmental impact arising out of it, extracting the valuable minerals in a selective manner for a higher efficiency in the processing plant.

The Wirtgen Group today has the widest range of surface miners which find application in many parts of the world for different applications. In India, though the use of surface miners has been successful in the coal and limestone sectors, they anticipate demand from the other sectors like bauxite as well in the future. Their model SM4200, which is the biggest surface miner, is now immensely popular in the coal and iron ore sectors in USA and Australia. This machine is capable of producing about 3,000 tonne/hour of coal. Wirtgen has variants of this machine suitable for both hard and soft formations.

Last year, at the Panchpatmali Bauxite Mine of NALCO surface miner of Vermeer, USA make was introduced on a trial basis. Despite initial apprehension about its working in very hard rock conditions, the 600HP T 1255 TL model unit achieved 400 T/hr production capacities.

Mass Production Techniques

As a global phenomenon, the pace of technological change had been especially rapid in the second half of the last century and the mechanisation of unit operations have led to the development of long wall technology with the concept of mass production in the coal mining industry. It was also aimed at reducing the number of accidents, dru?dgery, monotony and dangers to workers engaged in underground mining operations. The development of mass production tech?nology including long wall equipment, continuous miners, ploughs and shearers, has been accom?panied by a series of incremental and innovative deve?lopments in roof supporting practices.

India also followed the world trend in 1975. 'Project Black Diamond' envisaged introduction of 130 Power Support Long wall (PSLW) faces by the year 2000. Initially, the first fully mechanised self- advancing PSLW face was introduced in the Moonidih mine in the Jharia Coalfield in 1978. Subsequently more mines were planned with PSLW in the Eighties, namely, East Katras (BCCL), Seetalpur, Dhemo-Main, Jhanjra, Khottadih (ECL), Patharkhera (WCL) and Churcha (SECL), and the first long wall in SCCL was introduced at GDK 7 incline in 1983 followed by a few other mines. In the process, about 30 PSLW sets have been imported from different sources in different countries like the UK, Poland, Russia, Germany, France and China. Barring a few exceptions, the Power Support Long wall faces gained moderate success. Most of the Long wall faces were far from the desired level of production and productivity on sustainable basis.

In addition, large-scale introduction of long wall technology received severe setbacks due to its successive failures at the Churcha (SECL) and Khottadih (ECL) mines.

At present, long wall mining accounts for a meager production of about 4 per cent of the total underground coal production. Now, when India is geared up to open up new mines on the PPP model in the coal sector to adopt mass production technology, the coming years will see adoption of some of the best technologies of the world.

Non-coal Mining

In the non-coal mining sector having metallic, non-metallic and atomic minerals, the production is on a rise in the last decade. The most significant achievements have been in the opening up of new surface uranium mine of UCIL near Jamshedpur. The one-time low production iron ore mines which had a capacity below one million tones, jacked up their production many times over, through introduction of hydraulic excavator with dump trucks of 50/85T capacities and mobile crushing system. However, producers like SAIL, TISCO and NMDC continued to replace low capacity rope shovels and dump trucks with higher versions.

In the non-metallic sector, HZL's Rampura Agucha Mine continues to be the world's largest zinc mine with an annual ore production capacity of 6.0 million tonne. In FY 2010, it had produced 612.94 kt of contained zinc and 55.10 kt of contained lead. HZL had completed commissioning of 1 mtpa concentrator in March 2010, and has enhanced its ore production capacity from 5 to 6 mtpa. The mine is equipped with state-of-the-art infrastructural facilities including the latest generation slope monitoring radar system; truck dispatch system; in-house central workshop and heavy vehicle service centre and repair shop equipped with requisite facilities.

The operations of HCL were more prominent from their Malanjkhand Copper mine. With increase in the depth of the Malanjkhand mine, HCL management is on the look-out for adopting underground methods to mine copper ore.

In bauxite mining, Nalco continues to lead the list with over 6.24 million tonne per year of expanded bauxite mining from the Panchpatmali bauxite mine in Odisha. This expanded capacity is in line with their enhancement of alumina and aluminium refinery capacity after expansion. Nalco mines have also adopted several measures to maintain the high quality and profitability through replacement of mining machinery with efficient hydraulic excavators, dump trucks and dozers. Nalco has also succeeded in the introduction of truck dispatch system to improvement productivity and quality.

To conclude, the Indian mining scenario is all set to break the previous records of production with enhanced coal, metallic and non-metallic minerals production. The more significant aspect is the timely entry into new uranium mining segments in Andhra Pradesh, which when fully operational will make India self-sufficient in uranium. With the growing production, the need for mining machinery will also get a boost and new high capacity units will be under utilisation. The only temporary roadblock in the capacity increase in iron ore mining is the multi-pronged regulatory mechanism in action, due to the past many years of unplanned illegal mining in some sectors.