Industry: Mining

Guaranteed system availability is critical to safety at Lonmin’s smelter complex

Goals

  • Seamless system redundancy
  • Improved system availability and reliability

Solutions and Products

  • System Platform
  • Historian
  • InTouch
  • InTouch Terminal Services
  • ACP ThinManager

Challenges

  • Major system reorganisation without any interruption to production

Results

  • Identification and correction of objects that weren’t optimal
  • More stable platforms running at lower server and engine utilisation.
  • More reliable hardware as well as improved software redundancy
  • Lower cost of ownership by replacing PCs with thin clients
  • Simplified replacement strategy in terms of upgrades, replacements and breakdowns

Marikana, North-West Province, South Africa – Lonmin’s extensive smelter complex at Marikana consists of various operations that range from extractive metallurgical processes to pyrometallurgical processes. The hazards associated with an environment of superheated molten material being produced, handled and controlled within the smelter operation demand nothing less than the highest-availability fail-safe control systems.

Background

The Marikana operation consists of various deep and shallow mining shafts, 11 concentrators, a smelter, a base metal refinery and a precious metals refinery (figure 1). The smelter has five electric arc furnaces (1 X 28 MW, 1 X 15 MW and 3 X 5 MW), a slag concentrator, 3 P/S converters, a concentrate drying plant and an SO2 gas treatment plant.

The various operations are mainly monitored and controlled through 16 different Wonderware ArchestrA-based System Platforms. The original system consisted of:

  • A general data repository
  • 8 Application Object Servers (AOS) with shared redundancy
  • 2 Historians
  • 12 desktop operation stations including 2 video wall monitoring systems.
  • 9 panel PCs where local operation and monitoring is required.
  • A Terminal Server for remote business reviews and monitoring.
  • A total I/O count of 252 893 tags

The Problem

“Before the replacement of the Proficy iFIX system in 2011, we had decided that the new system must either provide a true hot-backup capability or seamless redundancy,” says Percy French, Automation Manager, Lonmin plc. “We found the answer with Wonderware’s ArchestrA-based system platform which is especially well-suited to mission critical applications.”

After the implementation of System Platform in 2012, Lonmin re-evaluated the installation in order to assess and review the risk factors associated with their system topology. During the review, the following risks were identified:

Hardware risks

  • The effectiveness and availability of the plant control network infrastructure, especially with regard to redundancy and reliability
  • The reliability and availability of desktop computers and panel PCs

Software risks

  • Unstable redundancy operation of engines and servers
  • Reliability of desktop operator stations and local operator station deployments (including operating systems)
  • The reliability of I/O drivers
  • The need for greater system access security and the elimination of threats from viruses.
  • The lack of human resources with adequate knowledge of the system configuration and setup

“The next step was to investigate and look for solutions that would minimise these risks,” says French. “This was done with a joint partnership of the in-house Lonmin team and the Wonderware Southern Africa technical team.”

The Solution

The conclusion was to implement a more advanced design to allow for the systems to be maintained and upgraded without compromising service availability. To achieve this, the following initiatives were identified:

Hardware

  • Implementing a ring LAN topology – this would help mitigate the consequences of network failures.
  • Investigating the use of thin client computers – This would be especially useful in mission-critical stand-alone applications. Apart from cost benefits, thin clients have numerous advantages over their PC counterparts in the industrial environment and would go a long way to addressing Lonmin’s concerns regarding the security, availability and reliability of PCs and panel computers. Thin client computers are robust and have no moving parts (fans, disc drives), can be easily and quickly replaced in case of failure (all software and configurations are in the server), don’t have USB ports so that viruses can’t be introduced into the system and lower system maintenance costs as all updates are done at one central location rather than at each workstation. With this arrangement, however, seamless server redundancy is of paramount importance.

Software

  • Improving Application Object Server (AOS) redundancy
  • Implementing load balancing and optimising engine redundancy settings
  • Separating mission-critical platforms to ensure that critical parts of the plant do not influence each other, especially during maintenance
  • Implementing remote monitoring and warning systems

“Instead of running backup engines and mission-critical engines on the same server, we rearranged application engines based on I/O count in order to balance server utilisation as well as to free up hardware resources,” says French. “The aim was to free up at least two servers to be used as mission-critical servers and to utilise them as redundant partners. The result was that we achieved our goal of seamless fail over.”

With regard to the thin client configuration, Lonmin selected the Arista suite of thin computer products and ACP ThinManager software together with InTouch Terminal Services software.

Benefits

  • The project helped Lonmin identify and correct substandard implemented objects, tags and other system components that did not contribute to the new system performance goals
  • More stable platforms running at lower server and engine utilisation
  • More reliable hardware as well as improved software redundancy
  • Lower cost of ownership as all desktop PCs will be replaced by thin clients and only terminal servers will be maintained
  • Simplified replacement strategy in terms of upgrades, replacements and breakdowns
Lonmin