Tag Archives: surface mining

Vermeer Terrain Leveler surface miner delivers results in Chile

In 2017, a prominent non-metallic mine in Iquique, Chile, began using precision surface mining methods. The mine had a goal of taking a broader approach and evaluating the benefits of precision surface mining from pit to heap leach. Results have been measured and compared with traditional drill and blast methods, and after almost 3 Mt of material cut, the benefits are sound and clear. The mining operation has reported positive results in the areas of material separation, better access in areas that were off limits before, more consistent particle sizes and gains in the heap leaching process.

César Leite, Vermeer Regional Manager for Chile and Specialty Excavation, said that surface mining operations throughout the region have put precision surface mining machines, like the Vermeer T1655 Commander® 3 Terrain Leveler® surface excavation machine (SEM), to work and been happy with the results. “We’ve helped many surface mining operations in the region deploy precision surface mining methods that help address many challenges associated with traditional methods,” he explained.

Safety

Safety while working with explosives used for drilling and blasting has been a major focus area for the mines in Chile. “It is not just the nature of the traditional process that makes it risky, but the number of people involved,” Leite said. “With the precision surface mining process, workers have a controlled way of extracting material, and the process does not have a single step where high levels of energy are stored and released.”

Precision work

Precision surface mining has also helped dilution issues because of the way the Terrain Leveler SEM cuts material in layers. With a modulable cutting depth, miners can be highly selective in the way they recover the mining ore with minimum presence – if any – of sterile material. Geological mapping of the pit can result in less dilution. It can help improve efficiencies through the whole process from loading and hauling of rich and concentrated mineral ore to a heap leaching process with a high level of mineral recovery.

Exclusion areas

The amount of energies stored and released by blasting can cause significant ground vibration, which is why many mines have areas that are off limits to traditional methods. Selective surface mining has provided a unique solution for some Chilean mines, by exploiting these massive areas otherwise prohibited. Using surface mining machines has opened about 80,000 sq.m of new areas in Chile near roads, warehouses, medium voltage lines and other areas previously unavailable.

A Vermeer T1655 Commander 3 Terrain Leveler surface excavation machine (SEM) on a job site in Chile

Particle size

In non-metallic surface mining operations, the effectiveness of the leaching process can be affected by the direct particle size output of the blasting stage. “In normal conditions, blasting is simply not able to control or guarantee a consistent particle size,” Leite explained. “Inconsistent particle sizing can result in poor recovery during heap leaching stages. With selective surface mining, there is a high level of consistency in particle sizes, which can result in better mineral recovery in latter heap leaching stages. On top of that, avoiding big chunks of rocks – very common in blasting – increases the efficiency of the hauling process as more material is transported in a given spatial volume.”

Around 95% of the material cut with the Terrain Leveler SEM produced particle sizes below 25.4 cm.

Heap leaching process

As with every mining activity, there are details that will provide a clear insight into any improvements introduced in previous stages. In some of the non-metallic mining operations, heap leaching is the key process that will clearly show the benefit of a given innovation. The heap leaching process happens slowly, so – although the insight is clear – it takes time to realise the benefit of any given change in the previous stages. The required time for a heap to deliver all the mineral recovered may vary depending on heap dimensions, particle size consistency, leach solution and some other factors. On average, 12 months seems to be a very common time frame for a heap to deliver its benefits. Naturally, the shorter the period, the better to recover the same amount of mineral, but if there’s even more mineral recovered, then it is simply a remarkable result. This is precisely what was observed in Chile: more mineral recovered in less time.

The results of mineral recovery at heaps created exclusively by selective surface mining with the Vermeer Terrain Leveler SEM showed 12% more mineral recovery than heaps with traditional mining. This mineral recovery rate was achieved in a period 33% shorter than using traditional mining methods.

Surface-mining opportunities lie in market-related commodities

Johannesburg-based mining equipment distributor Vermeer Equipment Suppliers is starting to focus on certain market-related commodities and associated open-cast mines to market its surface excavation machines, says Mining and Pipeline Sales Segment Manager, Gareth Cramond.

The machines are being used in Africa at, among others, China Molybdenum’s Tenke Fungurume copper and cobalt mine, in the Democratic Republic of Congo, and exploration and mining services company Société Minière de Boké’s bauxite mines, in Guinea. In South Africa, the machines are being used at diversified miner Exxaro Resources’ Grootegeluk open-cast coal mine, in Limpopo.

Cramond says Vermeer wants to pursue other commodities that will be in demand within the next few years. He notes that the company is approaching mining companies that are mining certain market-related commodities.

The Vermeer surface excavation machine provides users with consistent material size, eliminating the need for primary crushers and increasing efficiencies of loaders and haul trucks. No permits for blasting are required either, the company says. This mining method also facilitates selective mining and selective loading, allowing for the ore to be more easily separated from waste.

Other advantages include access to areas of open-cast mines where drilling and blasting cannot be carried out because of physical or permit limitations, as well as a reduction in noise, dust and vibration, compared with drilling and blasting operations. The machine can mine at a maximum incline up to 30º.

Vermeer Equipment Suppliers MD, Frank Beerthuis, notes that this capability enables the machine to start mining directly after vegetation has been cleared, even on hills and slopes.

“Further, the equipment can remove overburden and, once the orebodies are exposed, mining can continue,” he says. “With drill and blast, a lot of mobilisation and demobilisation of equipment is needed to get to the orebody.”

Cramond argues that there are opportunities to use surface mining technology, such as Vermeer’s surface excavation machines, on existing mines that have “essentially mined themselves out” using traditional mining methods.

“If a mine has drilled and blasted to a certain depth and there is a certain span of their mine site for which they cannot use traditional methods, but there is enough of a commodity that makes it viable to further extend the life span of the mine, surface mining technology may be a unique consideration for them,” he explains.

Further, Vermeer has identified opportunities at greenfield mines in sub-Saharan Africa.

Cramond says that when a miner starts up a greenfield mine and can eliminate the primary crushing process to get the material into the market much quicker, surface mining becomes a viable option if it falls within the capability ranges of the surface mining technology that is going to be used.

Implementing surface excavation machines at greenfield mines can save time and may reduce the initial capital investment, as well as generate revenue much faster than traditional methods, he adds.

“The infrastructure is considerably less expensive to buy and is installed quicker than the construction of a large primary crushing plant, for example,” he says.

The quick start-up of the machines can enable existing mines to take advantage of spiking market prices, Cramond comments.

Implementing surface excavation machines at greenfield mines can save time and may reduce the initial capital investment, as well as generate revenue much faster than traditional methods, Gareth Cramond says

Tools and analysis

Vermeer says it has the tools and data to estimate how the surface excavation machines can perform at a mine. The estimation uses actual data from a mine operation to provide a more realistic estimate of how Vermeer’s technology may benefit a mine.

The company can carry out field testing using a point load tester to test material on site. If the material is within a range deemed acceptable, further testing will be required.

Moreover, Vermeer has its own dedicated rock laboratory in the US, to which interested mines’ rock samples are sent to determine production rates and cost of production of the company’s surface excavation machines in the client’s specific application. These samples are then subjected to various tests and the data is provided for the mine.

Cramond highlights that, even though there are numerous rock laboratories available, Vermeer orientates its rock-testing towards the capabilities of its machines, which enables the company to gain detailed information on the samples and the potential of job sites and compare these afterwards with real life production rates of the equipment. The company uses its in-house developed production calculator to formulate operational costs and production rates on a particular mine site.

If it has been determined that Vermeer’s surface excavation machines are suited to a mine’s operations, the client is given the option to either trial the equipment or visit a mine where the company’s equipment is being used in a similar application.

When trialing the equipment, Vermeer conducts a complete efficiency analysis of the mine and provides this data for the client. Trialing can take from two weeks to three months.

“The future of mining lies in using innovative techniques and three-dimensional digital technology-based methods,” Cramond concludes.