Money to burn?

2011 Jul 25

“Sustainability” is a popular word nowadays and in the mining industry it is often used in connection with the future. However, at a recent international conference Atlas Copco’s Lars Bergkvist told delegates that sustainability is already within the grasp of every mine on the planet.

Mining companies looking to achieve long-term sustainability goals do not have to look far. Neither do they have to invest huge sums of money to get results. Instead, the key components of sustainability are already close at hand and just waiting to be discovered.

That was the message from Lars Bergkvist, Atlas Copco’s Senior Advisor Mining, when he recently addressed delegates at SDIMI 2011, the International Symposium of Mining Engineering held in Aachen, Germany.

This event brought together mining engineers from around the world to discuss the efforts required to achieve sustainable operations.

Bergkvist took the opportunity to challenge the common belief that sustainability is a major undertaking and pointed out that at some mines, sustainability is simply a case of “good housekeeping” – in other words, better resources management. Back in Sweden, Bergkvist elaborated on his views for M&C readers.

Easier than many believe
“The term ‘sustainable mining’ refers to an operation that is run so efficiently in good times that it has the stability to survive and prosper over the long term, including during down periods. It naturally follows that a sustainable mine is one that is also sustainable from an environmental point of view, which is an equally important goal.

“Unfortunately, there are many mines that are far from achieving this level of sustainability. Either they are too busy meeting demands during the current boom so they don’t have time to address the issues, or they believe that it is such a big issue, requiring a lot of time and investment that they push it into the future. It is also very common for a mine’s purchasing strategy to focus more on price than on the total cost of a system with all parameters taken into account.

“In my view, sustainability is easier and quicker to achieve than many com­panies think. The answer lies in the use of resources and the potential for savings through increased efficiency.”

War on waste
While many mines may exercise outstanding control over the way they use resources such as water, compressed air and electricity, he maintains that others are not taking full advantage of the available opportunities for improvement.

“Take water and water retention, for example. Water is primarily used for flushing drill holes to bind cuttings and dust part­icles but also for increasing productivity. The greater the speed of the rock drill, the greater the need for water.

“The cost of providing and retaining water constantly increases, partly because of increased consumption by individual drilling units, but also because of mining at greater depths where transporting water upwards requires more powerful pumps and more energy to drive them.

“There is great potential here for discovering intelligent solutions such as Atlas Copco’s water mist system, a mixture of incoming flushing water and air which can reduce the need for flushing water by up to 80 percent. Compressed air is also expensive but it is still worth considering.

“In addition, large volumes of water are often pumped over long distances at high cost and this can be changed by recycling the water closer to the worksite.”

The way compressed air supplies are arranged is another area that needs close attention, Bergkvist maintains. Often the air is supplied from a fixed installation on the surface and is delivered into the mine by running galvanized pipe bolted together every five meters, usually along the walls of the ramp or in a shaft. This pipe system can be up to several kilometers long with great risk of leakage from the joints.

“I know of cases where probably half of the compressed air just escapes along the way and goes to waste. Even the best system can lose about 30 percent,” he says. “Imagine a 1 000 meter deep shaft mine with a one kilometer pipe down the shaft.That’s 200 joints in the shaft alone, not to mention all the joints that run to every production area. But there is a solution here, too. Install the compressors under ground, close to where the air will be used. This will reduce leakage and the cost of the electricity needed to drive the air such long distances.”

A better way to ventilate
While diesel operated equipment has raised productivity in mining, it has also increased the need for ventilation and this often accounts for the greatest unit cost for power. Bergkvist explains: “Some mines are losing fortunes in ventilation costs because they allow these systems to operate at full flow at all production points at the same time, even in areas where no mining is taking place.
“By only making ventilation available in the areas where it is needed, the consumption can be reduced significantly – in other words, ventilation on demand. This can be done by regulating the air flow frequency in the ventilation fans. Frequency control provides ventilation only where it is needed and closes it down in areas that are lying dormant.

“Ventilation is also a question of reducing fuel consumption and the amount of exhaust gases to be ventilated. Our RCS computer controlled loaders reduce fuel consumption by 30 percent and can provide data on the ventilation requirements of each unit – a function that is performed automatically, communicating with the ventilation system online.”

As the price of oil and electricity is expected to remain high in the future, all mines will have to consider their energy costs when deciding what equipment to buy. Cable lengths, for example, can be reduced by up to 90 percent by drilling so-called service holes for installing electricity connections in the rock instead of in existing drift systems. Atlas Copco Robbins 34 RH, which is primarily designed for raiseboring, can also drill high precision pilot holes for service holes of 254 mm up to 610 m in length.

“Reduced cable length means less disruption and reduced risk of damage to the installations by large vehicles in tight spaces,” says Bergkvist. “If damage does occur, causing a power failure, all or part of the operation has to stop while the damage is repaired, with costly disruption to production .”

Total process optimization
Bergkvist concludes: “Increasing productivity for our customers is the foundation for all of Atlas Copco’s business activities. But we are also committed to sustainable productivity which means we always take the long term view. Our customers need to know that they will be productive, not just today or tomorrow, but a year or even ten years from now.

“An underground mine is a process system with many different unit operations that need to work together to achieve optimal conditions and by bringing monitoring to a higher level it provides an opportunity to optimize the entire value chain.

“It’s a question of achieving total process optimization and with today’s modern equipment and communications systems it is now easier to get an overview by gathering selected data. “I believe it is time to focus on the totality that is required in order to achieve the best overall solution.”

Footnote:
Mining engineers will get a chance to hear Lars Bergkvist at the 22nd World Mining Congress due to be held in Istanbul, Turkey September 11–16.

 

Epiroc operated under the trademark “Atlas Copco” prior to January 1, 2018.