Charging ahead in Chile

2014 Jan 09

Pucobre continues to show the way with the latest technology

Chilean mining company Sociedad Punta del Cobre (Pucobre) was one of the first to adopt mechanized charging techniques. Today, some 40 years on, the company remains in the forefront of this technology, sourcing all of its charging equipment from Atlas Copco GIA.

The move towards mechanized charging began in 1974 when the company was expanding its Punta del Cobre copper mine in the Atacama region, one of the largest copper deposits in the world. At that time, the blastholes for this sublevel stoping operation were drilled with light, handheld, Atlas Copco rock drills, and the holes were charged with ANFO (ammonium nitrate/fuel oil explosive) using a manually operated tool.

There were two operators for each unit, one managing the suction line inside the sack and a master charger who charged the hole. In addition, the work was done manually from a wooden platform, mounted on the bucket of a loader.

Time to improve

As techniques evolved, this task was eventually carried out using specially designed charging equipment called ANOL, also supplied by Atlas Copco, and a ladder was used for charging at higher levels.

In 1988, the mine decided that it needed to improve on the efficiency of its charging operations in order to increase production, and ANFO self-propulsion loading equipment was introduced for face development and production blasting. This equipmen­t, ANFO PT-61, also supplied by Atlas Copco, was a big improvement. It enabled the mine to replace all manual charging with a system of electrically operated hydraulic pumps mounted on a carrier, with a diesel engine for tramming.

The charging of long production blastholes, typically positioned high at the face, was carried out with JET-ANOL from a platform consisting of wooden boards on top of drums and from a front loader. The master charger would position himself inside the bucket and fill the holes from there, improving charging at heights.

Good combination

Segundo Espinoza, who manage­s the charging operations at the mine, notes that all of the mechanized charging equipment at the mine is from Atlas Copc­o GIA, and that these units are well matched to the mine?s fleet of Atlas Copco drill rigs.

For example, Atlas Copco Boomer 282 rigs, equipped with 4.5 m drill rods, are used to drill 45 mm horizontal production holes which are then charged using Atlas Copco GIA?s Chargetec UV1 and Chargetec 2 charging trucks.

In addition, it is now possible to use ANOL CC with this equipment making it ideal for charging both horizontal as well as long holes. The fleet, which also includes Boomer M2 C as well as Simba 254 and M4 C rigs, is in operation every day and completes about 7?000 m per month.

All of the previous charging equipment has been electro-hydraulic with diesel engines used only for tramming. Now, however, the mine?s charging operations have taken another big step forward with its latest acquisition, the Chargetec UV2.

Optimum blasting

This new multi-directional, ANFO charging truck is the first diesel-hydraulic unit  that is capable of working anywhere in the mine, including in areas without electrical installations. It also has a stronger boom and improved reliability overall, compared with its predecessors. But more importantly, it has a combined compressor and JET-Anol system that enables the operator to precisely adjust the density of the charge to ensure optimum blasting results. This, in turn, is supported  by the combined ejector/compressed air blending vessel which ensures the correct flow of ANFO at an even and precise density.

 The use of these charging trucks has successively enabled Pucobre?s operators to do their work in a safer and more efficient way. It has also led to a reduction in the time previously required to charge holes by approximately 50%.

Similarly, with ANFO PT-61, it has been possible to reduce the number of operators from four to two, making better use of resources.

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