219
Na 2 O, K 2 O, S and P. Given the presence of these different mineral compositions in the mine,
the iron concentration ranges from 22–40%, giving an average value of 33%.
The Erzberg mine has been in operation for more than 1300 years. The deposit was initially
mined using underground methods. Later, in 1890, the mining was changed to open-pit, with
mining done in benches. In 1986, underground operations were totally ceased and open-pit
mining became the only method. As per current production and reserve estimation, the mine
can be operating for another 30–35 years.
Currently, The Austrian mining company VA Erzberg is carrying out the mining activity
with a workforce of about 250 persons. The mine has a total of 31 benches, of which 21 are
currently active. A total of about 12 million tons of rock, including 8 million tons of waste,
is mined out annually using conventional drill and blast technique. Because of the varying
nature of the ore quality, different short term and long term plans have been made using
deposit models to maintain a good balance of iron concentration for processing purposes.
After blasting, the waste is dumped in a nearby dump area, and the ore is hauled to the
crushers. Two gyratory crushers (with a capacity of 1200 tons per hour) break the boulders
and bigger pieces of rock into a maximum particle size of 15 centimeters. The crushed material is processed further to remove the waste from the ore. This processing phase includes
sensor based sorting for the high quality ore (iron content > 30%) and dense media separation
for the low quality ore. After removal of the waste, 3 million tons of ore are crushed again
to achieve the final product size of 2–10 mm in diameter which are transported to Linz and
Donawitz for processing into high quality steel.
2.2 Measurement while drilling
In the Erzberg mine, drilling is done with fully mechanized Epiroc D65 drill rigs equipped with
pneumatic Down-The-Hole (DTH) hammers. The Epiroc drill monitoring system retrieves
and stores MWD data. The recorded data include time (YYYY-MM-DDThh:mm:ss), depth
(m), penetration rate (m/min), feed pressure (bar), rotation pressure (bar), and percussive
pressure (water pressure measured by bar). The sampling interval along the borehole is set
to 5 cm. On each drill rig MWD data are stored on a USB memory. For this test MWD data
were collected from two different bench faces for a total of 14 boreholes. The length of the
boreholes was approximately 30 m.
2.3 Image collection
For this study, stereoscopic images were taken using a Nikon D70 s camera with an 18 mm
zoom lens. The camera was calibrated and provided by 3GSM as a component of the ShapeMetriX3D software package. At least two images (stereoscopic image pair) are required to
generate a 3D model. Several images were taken parallel to the bench face, and the best ones
were used for further processing. For the software, the distance between the imaging points
(baseline distance) should be about 1/10 to 1/8 of the distance between the imaging point and
the rock face (3GSM, 2010). The standard procedure to take stereoscopic images for ShapeMetriX3D is described by 3GSM (2010) and Gaich et al. (2006). Figure 1 shows the image
of one of the benches at the mine site.
Range poles with target discs can be seen in the image that are used for referencing and
scaling the 3D models. The coordinates of the range poles were determined using GPS and
used for referencing the 3D model in a global co-ordinates system.
2.4 Model generation
The software has a special tool, ‘Reconstruction Assistant’, to convert the stereoscopic image
pair into a 3D image. The images were loaded onto the software, and 3D models were generated using this tool. Another tool, ‘Surface Trimmer’, was used to edit the 3D images to
remove the undesired areas from the images. Finally, the software’s ‘Referencer’ tool was used
to reference the generic 3D images onto global co-ordinates system. These steps follow the
Na 2 O, K 2 O, S and P. Given the presence of these different mineral compositions in the mine,
the iron concentration ranges from 22–40%, giving an average value of 33%.
The Erzberg mine has been in operation for more than 1300 years. The deposit was initially
mined using underground methods. Later, in 1890, the mining was changed to open-pit, with
mining done in benches. In 1986, underground operations were totally ceased and open-pit
mining became the only method. As per current production and reserve estimation, the mine
can be operating for another 30–35 years.
Currently, The Austrian mining company VA Erzberg is carrying out the mining activity
with a workforce of about 250 persons. The mine has a total of 31 benches, of which 21 are
currently active. A total of about 12 million tons of rock, including 8 million tons of waste,
is mined out annually using conventional drill and blast technique. Because of the varying
nature of the ore quality, different short term and long term plans have been made using
deposit models to maintain a good balance of iron concentration for processing purposes.
After blasting, the waste is dumped in a nearby dump area, and the ore is hauled to the
crushers. Two gyratory crushers (with a capacity of 1200 tons per hour) break the boulders
and bigger pieces of rock into a maximum particle size of 15 centimeters. The crushed material is processed further to remove the waste from the ore. This processing phase includes
sensor based sorting for the high quality ore (iron content > 30%) and dense media separation
for the low quality ore. After removal of the waste, 3 million tons of ore are crushed again
to achieve the final product size of 2–10 mm in diameter which are transported to Linz and
Donawitz for processing into high quality steel.
2.2 Measurement while drilling
In the Erzberg mine, drilling is done with fully mechanized Epiroc D65 drill rigs equipped with
pneumatic Down-The-Hole (DTH) hammers. The Epiroc drill monitoring system retrieves
and stores MWD data. The recorded data include time (YYYY-MM-DDThh:mm:ss), depth
(m), penetration rate (m/min), feed pressure (bar), rotation pressure (bar), and percussive
pressure (water pressure measured by bar). The sampling interval along the borehole is set
to 5 cm. On each drill rig MWD data are stored on a USB memory. For this test MWD data
were collected from two different bench faces for a total of 14 boreholes. The length of the
boreholes was approximately 30 m.
2.3 Image collection
For this study, stereoscopic images were taken using a Nikon D70 s camera with an 18 mm
zoom lens. The camera was calibrated and provided by 3GSM as a component of the ShapeMetriX3D software package. At least two images (stereoscopic image pair) are required to
generate a 3D model. Several images were taken parallel to the bench face, and the best ones
were used for further processing. For the software, the distance between the imaging points
(baseline distance) should be about 1/10 to 1/8 of the distance between the imaging point and
the rock face (3GSM, 2010). The standard procedure to take stereoscopic images for ShapeMetriX3D is described by 3GSM (2010) and Gaich et al. (2006). Figure 1 shows the image
of one of the benches at the mine site.
Range poles with target discs can be seen in the image that are used for referencing and
scaling the 3D models. The coordinates of the range poles were determined using GPS and
used for referencing the 3D model in a global co-ordinates system.
2.4 Model generation
The software has a special tool, ‘Reconstruction Assistant’, to convert the stereoscopic image
pair into a 3D image. The images were loaded onto the software, and 3D models were generated using this tool. Another tool, ‘Surface Trimmer’, was used to edit the 3D images to
remove the undesired areas from the images. Finally, the software’s ‘Referencer’ tool was used
to reference the generic 3D images onto global co-ordinates system. These steps follow the