Exploration in the mountains of Molango

2013 Jan 07

A fleet of exploration drilling rigs are hard at work in the Molango district. Their mission: to establish new manganese ore fields to meet growing world demand.


About a four-hour drive northwards from Mexico City lies the vast and stunningly beautiful mountain region of Molango. But it?s not just breathtaking scenery that characterizes this Mexican landscape. It is also home to the country?s largest deposits of manganese.

Here, mining company Compania Minera Autlan, part of the Ferrominero group (GFM), is producing and marketing world class manganese ore and ferroalloys and is pursuing an ambitious expansion plan.

Autlan?s concession stretches across an area of some 1 000 km2 and to establish its future potential it has multiple properties currently undergoing extensive exploration.

To carry out the work, Autlan uses Atlas Copco exploration drill rigs to take core samples made up of both oxidized and carbonized rock.

M&C visited two of the properties ? the Molango Unit, which produces 800?000 tonnes of Mn per year, and the Nonoalco Unit, which produces 150?000 tonnes per year, including both manganese oxides and manganese carbonate. Their combined exploration target is 17?000 core drill meters per year.

First on the scene

When the company decided to expand its exploration fleet, the Atlas Copco Diamec U6 was its first choice. Compact and agile, the Diamec U6 provided high mobility in the rugged terrain, in contrast to the other rigs in the mine?s fleet which lacked mobility and demanded more service than the manufacturer was able to provide.

Impressed by the rig?s performance after two months of operation, the mine attempted to order a second Diamec U6, only to find that it had been redesigned and was no longer available with the crawler configuration. The answer was not far away ? Atlas Copco?s Christensen CS14C.

While the compact Diamec U6 will get into more confined spaces, the longer mast of the Christensen CS14C provides longer core barrels. In terms of production, the Diamec U6 achieves 20 m per shift while the Christensen CS14C gives 28 m per shift. On average, six hours are spent drilling in every eight-hour shift, irrespective of rig model.

The rig of choice

Comparing the rigs? performance, Guadalupe Martínez, Drilling Superintendent, says: ?The Diamec is drilling about 800 meters per month and the Christensen is drilling about 1?000 meters per month. The other rigs we have only drilled between 600 and 700 meters per month.?

Guadalupe Martínez explains that the Christensen CS14C is now the rig of choice. ?The Christensen rig produces a 1.5 meter core barrel ten minutes faster than the Diamec,? he says, and adds that the rig also saves time in handling pipe due to its 6 m long mast.

In the Molango operation, the Diamec U6 drills 50 m deep vertical holes with HQ size pipe on the mountaintops. Holes spaced 20 m apart are drilled to define the depth of the ore body. Once the ore body is defined, it will be mined using excavators as the loose and unconsolidated formation does not require drilling and blasting.

Different routines

The Christensen CS14C drill and other similar rigs in the fleet, work according to a different routine. The drilling positions are spaced 20 m apart, but at each position they drill three holes. The first is 180 m deep at an incline of 80 degrees. Then another is drilled to 270 m after the tower is adjusted to 55 degrees and the third is then drilled to 220 m deep at 40 degrees. The first 100 m is usually overburden and the ore body is approximately 60 m in depth.

?Although the projected total meters drilled is similar,? explains Mine Manager Ronaldo Lugo Corpus. ?The Atlas Copco rigs drill at half the drilling cost of another manufacturer?s drill. They don?t require anchoring which allows them to get into position and they start drilling much faster. It?s quicker to get from hole to hole which means we can greatly increase productivity.?

He adds that he likes how the Atlas Copco rigs are able to go wherever they are needed and drill the various types of holes, and Martínez, Mine Superintendent Drilling, adds that he appreciates the simplicity of maintenance and service.

As the mine continues to push for growth, it is looking forward to taking delivery of two more Christensen CS14C rigs which will further boost its exploration capacity and support its future mining needs.

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