Upgrades to mine increase plant efficiency

2nd November 2018 By: Thabi Madiba - Creamer Media Senior Research Assistant and Reporter

Upgrades to mine  increase plant efficiency

INDOOR The upgraded SBV vacuum circuit breaker switchboard offers higher continuously rated currents

Mining electrical equipment manufacturer Emis Sales 2002 has completed upgrade projects comprising the design and installation of communication, automation and protection systems at South African anthracite producer and exporter Zululand Anthracite Colliery (ZAC), in KwaZulu-Natal, to improve productivity.

The initial project at the MacNelly plant was the upgrade of the 11 kV plant substation, which involved replacing outdated equipment, old circuit breakers and a ring main unit during a planned shutdown, says Emis Sales 2002 MD Frikkie Quirk.

“All upgrade projects for ZAC, which were installed and commissioned on time, have resulted in improved efficiencies, greater productivity and energy savings on the mine.”

Emis Sales 2002 is a subsidiary of automation manufacturer and supplier Becker Mining South Africa (SA). The project involved the upgrade of the existing switchgear at the plant substation and the installation of communication, automation and protection systems at the plant. Becker Mining was also responsible for the design and installation of advancements at the mine’s main washing and siding plants, as well as the establishment of a leading-edge control room.

The advanced Actom SBV vacuum circuit breaker switchboard comprises a main feed from the mine’s main substation and two standby generators. Quirk explains that, once synchronisation has been completed, generators can be brought online as part of the recent automation scheme at the mine.

The project also required the installation of Becker ProBeck motor protection and control relays to replace all outdated systems on chassis plates in the motor control centre (mcc). Single start/stop devices throughout the plant have been replaced with sequences starting through programmable logic controllers (PLCs) and all direct online motors were replaced with soft-starters as needed. He says, since the installation, there has been a 20% increase in productivity at the plant.

Other advancements include PLC automation, fault recording, and a belt feedback monitoring and communication system, which are installed and monitored using Becker Wi-Fi to the control room, with live data. He also added that Becker Mining SA does their own PLC programming and supervisory control and data acquisition.

The main wash plant was previously operated manually and included stop/start push buttons, manual communication, shift reporting and outdated PLC technology, with no backup facility. Quirk explains that the upgrades include the replacement of mcc buckets with Becker ProBeck motor protection and control relays, which he says has seen a 27% increase in plant efficiency, and has also resulted in a 50% reduction in pump replacements, as a result of correct motor protection.

Becker ProBeck motor protection and control relays have been replaced in mcc buckets and new PLC technology controls automatic start-up and stops in the event of blockages. A highly efficient ten sequence start system has replaced the previous operation, where 135 starts were used to control the plant’s sequence starting.

“For optimum performance at the plant and to ensure extended service life of all components, maintenance is now planned. True data – including shift reports and maintenance information – is automatically captured and communicated back to the control room. The new control desk is less than a third of its original size,” he explains.

Moreover, siding plant upgrades include the installation of six soft starters for motor applications and one variable- frequency drive motor, to replace direct online starters. Quirk mentions that all motors now have an automatic start-up using one start button to PLC and are programmed to stop in sequence. He adds that apart from improved efficiencies, an important advantage of the new system is energy savings.

Further, the establishment of a new control room at the plant provides full control over production and plant availability, as well as at the control room. “All communication and data capture systems are now fully automated. More accurate forecasting can now be done, using the relevant data provided, such as levels, densities and pressures. Using Becker ProBeck motor protection and control relays allows for critical information on motor currents, trip conditions and motor status to be readily available,” Quirk adds.

Proloc and ProBeck electronic relays for motors (which are available in 380V, 400 V, 525 V, 950 V and 1100V, and up to 3.3 kV and 6.6 kV), have features for electronic overload protection, earth insulation lockout, frozen or vacuum contact failure and earth leakage protection. He explains that other features include short circuit, frequency and power factor measurement, as well as minimum and maximum load, pump cavitation, over voltage, under voltage and cable theft protection.

Apart from the design and manufacture of a range of electrical products for hazardous and nonhazardous applications, Becker Mining SA also offers a repair and maintenance service to ensure total reliability of equipment in harsh operating environments.

Becker Mining SA’s specialist services to the mining sector include energy distribution, communications and automation solutions, mechanical and transportation systems and steel arch roof supports.