The Zest WEG Group, including EnI Electrical and Shaw Controls, has successfully completed an extensive contract, worth in excess of R200-million, at Lubambe Copper Zambia’s Konkola North Project.
This is the single biggest project of its kind that the Zest WEG Group has managed from a perspective of involvement from all group companies. EnI Electrical was instrumental in mitigating any delays in the construction phase, covering all electrical equipment and instrumentation and ensuring the project came in on time and within budget.
The scope of the Zest WEG Group’s contract, awarded in 2011, covered the supply of all electrical and instrumentation elements for the expansion infrastructure and wet plant. This includes MV and LV electric motors, MV Variable Speed Drives (VSDs), phase shift transformers and all motor control centres (MCCs), both containerised and free-standing, required for the entire facility.
“There has recently been a swing towards the use of big squirrel cage motors and VSDs for mill applications, compared with previous years where slip-ring motors were exclusively used,” Johan van Niekerk, manager automation at Zest WEG Group, says.
“At Konkola North we’ve supplied a 4.4 MW six-pole 3 300 V B3 WEG squirrel cage motor and a WEG MVW01 VSD on the SAG mill with a three-winding VSD transformer manufactured at the WEG factory in Brazil. The LV motors are the latest generation three phase W22 IE2 units, which conform to the efficiency specification IEC60034-30. Four specialised 950 kW 10-pole 11 000 V B3 WEG slip ring electric motors have been supplied to drive the ventilation fans.
“The WEG MVW01 VSD is particularly important in this application, because of its high frequency, in excess of 90% efficiency, which is critical on large kilowatt application where losses can be potentially high. These units are of a modular construction that makes operation and maintenance relatively simple and makes it possible to customise control software.
“For example, WEG has developed a frozen charge protection specific to mill applications, where the torque and angular rotation of the mill is monitored, allowing for the detection of frozen charges in the mill. In this event, the mill trips and alerts the operator before any damage can occur.”
Van Niekerk adds that another benefit of this approach is the combination of the VSD and three winding transformer that reduces the harmonics to levels that meet IEEE519.
All electrical infrastructure
Zest WEG Group company, EnI Electrical was responsible for the installation of all electrical infrastructure from the main utility substation to the consumer substation and the main Motor Control Centres (MCCs), as well as the supply of all electrical equipment including cables, racking and instrument cables. The electrical and instrument reticulation included fibre optic communications to the plant motors from the MCCs.
This work package included 11 KV overhead line reticulation in and around the plant, all lighting and small power, including six scissor high masts, electrical reticulation to all the ventilation shafts and five individual substations and the supply of all electrical cables and equipment for the underground portion of the project.
“EnI Electrical has managed to secure a significant portion of the electrical construction market in 2011/2012 and we’re well positioned to consolidate this position in the future,” Trevor Naude, sales and marketing manager at EnI Electrical, confirms.
Zest WEG Group Company, Shaw Controls secured 15 MCCs for the project, adding to the company’s reference base on the African continent.
The ball mill has been supplied with a 6.2 MW six-pole 11 000 V B3 WEG slip ring machine and the Zest WEG Group team was given the rare responsibility of supplying all controls and auxiliaries around the ball mill package, such as an isolator on the VSD and its interconnections.
The Zest WEG Group secured the supply of all the LV electric motors required for the project, both for the mining portion and for the process plant. In total, more than 500 units were supplied.
The Konkola North copper project, a 50:50 joint venture between African Rainbow Minerals (ARM) and Brazilian mining company Vale, project managed by DRA, is located near the town of Chililabombwe, adjacent to the Democratic Republic of Congo border and north of the Konkola Copper Mine. The mine is designed for a peak production of 2.5 million tons of ore and 0.6 million tons of waste rock per annum.
“Zest WEG Group companies have successfully completed projects individually or in combination for both ARM and Vale in the past,” David Claassen, group business development manager at Zest WEG Group, says. “The Konkola North Project represents a significant milestone for our group because all our companies have made a contribution.
“Working ostensibly as a single source supplier on this project, our objective was to mitigate risk for our client and we’ve achieved this by providing technical assistance as a small, integrated team. Application engineering for the various packages was commissioned within our Group and the benefit of our engineering teams being able to co-ordinate with each other was that once the equipment arrived on site, no last-minute alignment was necessary.
“Effectively, one company has taken responsibility for a host of financial and technical solutions and we will continue to harness this capability that reflects our strategy to add value by integrating Zest WEG Group companies where products and services are complementary.
“We attribute the completion of our role in the Konkola North Project on schedule to having the correct senior team in place, overseeing a highly proficient technical team. This joint effort was further buoyed by the depth of experience the EnI Electrical team has accumulated from many other projects of this nature.”
With Zest WEG Group support available in Zambia, any additional products or technical assistance that became necessary during the commissioning phase were readily available.
The Zest WEG Group is an acknowledged leader in the supply of electric motors and drives, motor control panels, generator sets, transformers, energy solutions and ancillary products and services.