2011-02-21: An ABB solution – the most powerful of its kind in the world – is enabling the highly energy-intensive ore-grinding process at Australia’s largest gold mine to set benchmark levels of energy efficiency, productivity, process flexibility and displaced CO2 emissions.
The solution has been operating successfully since March 2010 at the Boddington Gold Mine in Australia, which was recently modernized and reopened by owners Newmont Mining Corp. at a cost of approximately AU$3 billion.
Boddington is currently being ramped up to its maximum throughput capacity of around 35 million tons a year, which it is expected to reach in 2011, thereby becoming the largest and most productive gold mine in Australia.
The rock at Boddington gold and copper mine in Australia is very hard, and requires a great deal of energy to break into pieces which can be processed. To do this, the mine commissioned the building of four very large and powerful rock grinding machines, known as high-pressure grinding rolls (HPGRs). They are efficiently controlled by an ABB drive system, consisting of eight units (two per HPGR). Each of the units is made up of an ACS1000 medium-voltage drive, converter transformer and squirrel cage induction motor.
According to Newmont, recoveries of gold and copper are already above design expectations, which is a timely and profitable boost for Newmont as gold prices are currently at an all-time high.
A key part of the process is the ultra-powerful ABB variable speed drive system that controls the four huge high pressure grinding rolls (HPGRs) that grind the rock into optimally sized pieces that can be fed to the ball mills for further processing into gold and copper.
Made by industry leader Polysius, these HPGRs are the biggest in operation anywhere in the world. Each one can grind up to 2,100 tons of material an hour and is driven by two ABB ACS1000 units each with a power rating of 2,800 kW.
The drive system enables the HPGRs to grind hard abrasive rock more productively, more energy efficiently and with less wear and tear on the machinery than conventional crushers and mills.
ABB drive systems have the fastest torque and speed response time of any technology on the market. They continuously adjust the speed of the grinding rolls in response to micro-second fluctuations in voltage and changes in size or type of media.
The result is maximum throughput at minimal energy consumption and with consistent product quality. According to Polysius, the HPGRs will reduce CO2 emissions by over 200,000 tons a year compared with conventional systems.
ABB is the world’s leading supplier of drive systems for HPGRs and has supplied all the previous world-record drive systems for HPGRs, including 2,500 kW solutions for the Cerro Verde and Peñasquito mines in Peru and Mexico respectively, and a 2,650 kW drive system for Moly Mines Spinifex Ridge mine in Australia.