Some of the world’s earliest zinc production took place in the area around Zawar Mines in the state of Rajasthan in western India. Archaeologists believe mining in the region dates back nearly 2,500 years. Today the mines are again at the forefront of mining innovation. Here, 200 metres below the surface of the ancient Aravali Hills, India’s first electro-hydraulic long-hole drilling rig – the Sandvik DL310-7 (Solo 5-7C) – is poised to revolutionize its underground mining industry.

Purchased by Hindustan Zinc Ltd, the rig was installed in Zawarmala mine – one of four mines at Zawar – in September 2008. Overseeing its operation has been Associate Manager Tushar Chakraborty.
“I learned about the concept of electro-hydraulic machines for underground mining when I was a student, but at that time no one had any idea when they would arrive in India,” Chakraborty says. “To think that I’m the guy looking after the very first is a great feeling.”

Hindustan Zinc’s decision to invest in the DL310-7 was the result of an urgent need to boost productivity and efficiency. Situated just south of the famous “Lake City” of Udaipur, the region is rich in deposits of lead and zinc. But Zawarmala mine was struggling to achieve production targets of 1,000 tonnes of ore per day because drill reserves were not being generated fast enough.

The DL310-7’s arrival has brought confidence that these targets can be sustained and even surpassed.
“Every mine in the entire world wants to enhance its production, and once you’ve done your explorations and development, the first thing you need for this is adequate drill reserves,” Chakraborty says. “This machine takes care of that.

“Obviously, the initial investments are huge, but at the end of the day what counts is the return on investment. One thing that’s absolutely predictable about today’s figures is that we’ll have a positive return on investment in a very short time span – maybe less than a year.”

Talks between Sandvik and Hindustan Zinc about the DL310-7 began in 2006. The mine’s management had been impressed by the rig’s performance figures around the world.
“We considered offers from a number of companies, but after discussions it was agreed that Sandvik was the one to go with,” says Balwant Rathore, Zawarmala mine’s manager. “A major factor in our decision was the quality of their after-sales service. Response time is quick, and they have a very positive attitude.”

Chakraborty explains the company’s thinking: “Technically, we had three questions. How can we enhance our rate of penetration? How can we achieve a greater drilling depth? And how feasible is it to move the machine from one place to another? In all these three parameters, the DL310-7 fit perfectly.”

Previously, two separate rigs – each requiring two operators – were in use at the mine: a conventional pneumatic rig for upward drilling and a down-the-hole (DTH) rig to drill downwards. The DL310-7’s ability to rotate its boom 360 degrees – and thus drill in all directions – enables it to take over the work of both and requires just one operator. The Sandvik rig is already achieving consistent top-hole drilling rates, and bottom-hole drilling is currently under stabilization. A further decisive factor convincing Hindustan Zinc to invest in the DL310-7 was that an entire sub-level can be eliminated. The rig’s capacity to drill holes accurately up to 38 metres long means that, on average, one extraction level and one sub-level can take the place of one extraction level and two sub-levels.

At Zawarmala, the cost of a 100-metre sub-level is around 1.2 million Indian rupees (18,000 euros), so this will be a huge saving in cost as well as time and labour. Rathore also points to other advantages such as reduced noise levels and ease of operation. There is also an unexpected benefit: a massive boost in staff morale. DL310-7 operator Chakanath Premnath agrees: “It’s a smooth, cool, good-operating machine that’s going to revolutionize mining in India.

Previously drilling was a big task, but this machine makes it easy to achieve all our targets. I’m proud that I’m first man in India to operate it.” Premnath was one of two Zawarmala mine employees to be trained as operators by a team of Sandvik engineers who came from Finland to oversee the DL310-7’s startup. The rig has proved so straightforward to handle that three more operators have since been trained in-house.

According to Zawar Mines General Manager Amit Kumar Bhaumik, the DL310-7’s performance looks set to further investments in Sandvik rigs.

“Hindustan Zinc has a very ambitious future, and we think of Sandvik as our partners,” he says.
“We have a lot of new developments coming in – new mines, new expansions. So there’s a great deal of scope for these machines.”
Chakraborty adds, “Hindustan Zinc has taken a very big initiative to modernize its mines. We’re already working in a highly mechanized mine, and the arrival of this rig is a major benchmark.”

Jean Macfarlane

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