Whitehaven Coal
Narrabri Coal Loadout Facility Optimisation Project
- Gunnedah, NSW
- Allen Bradley ControlLogix PLC; Citect SCADA
Site Overview
The Narrabri coal mine is one of five mines operated by Whitehaven Coal in the Gunnedah Basin of NSW, Australia.
The mine is Whitehaven’s only underground operation and has been successfully operating since 2012, with current mine life up to 2044. It employs around 500 people, most of whom live locally, and produces approximately 11 million tonnes of high-quality thermal coal per annum.
All the coal produced by Whitehaven’s assets are transported along the railway for shipment at the Port of Newcastle.
Background
In 2021, the operations management staff at the Narrabri Coal Mine identified a need to improve the automation of the site’s Train Loadout (TLO) facility. There were both localised and company-wide business drivers for this, including:
- Material handling issues and the requirement for blending
- The variable nature of the train load rate, which was impacting the turnaround times as per load point agreements
- Downtime events from overloaded belts
- Resourcing constraints and inefficiencies
- A wish to debottleneck the TLO to allow optimised use of the rail line
A gap analysis of the existing control philosophy and operations of the TLO was also identified as a valuable exercise, as this could provide the site with a revised control strategy and additional functionality.
Project Scope
To support the optimisation of the TLO, Whitehaven engaged Mipac to undertake the abovementioned gap analysis of the existing control philosophy and operation of the TLO, with the aim to provide a revised control strategy with additional functionality for the site.
Mipac was chosen to complete this project thanks to its strong history of performing brownfield control optimisation projects, as well as its prior engagement in numerous successful projects at processing plants as well as train loadout facilities.
In summary, Mipac was engaged to:
Review the current operation of the reclaim system which feeds the train loadout bin, including:
- Existing documentation and site standard operating practice,
- Operator interface and navigation of SCADA HMI
- Historical train loading performance,
- Interviews and engagements with key parties involved such as production operations personnel, maintenance personnel, process engineer, control engineers, electrical resources and production superintendent,
- Control system logic code and configuration.
Optimise the train loadout system, including:
- Revisions and updates to the Functional Description,
- Updating and configuration of the control logic code,
- SCADA HMI clean up and improvements
- Developing site test documentation,
- Site based commissioning
Project Challenges
Throughout the project, several obstacles were identified that limited the system’s performance. These were identified both through discussions with operations and reviewing the existing controls around the TLO. These obstacles included:
- Modulating gates had a sluggish response – this was discovered to be a result of changes to the logic sequencing around valve activation for hydraulic pressure
- Extensive modification of reclaim logic since first implementation, due to conveyor bogging events over the years. This had resulted in multiple interlocks and restrictions being added as a safety net
- Frequent operator intervention during train loading, such as manual operation to adjust gate opening, as well as increased activation of the vibrating motors. The operator was essentially managing the material on the belt to provide sufficient material for loading the wagons at the desired train speed, whilst also managing the inventory in the surge bin as not to trip the conveyor or needing to stop the train.
Project Highlights
Various HMI improvements and updates were configured to improve transparency for operators of the controls around the TLO. The new control strategy recommended and implemented consisted of three elements:
- Direct reclaim feed rate control
- Ratio controller for blend management and compliance
- Constraint control during “live feed” scenarios
Project Outcomes
Key project outcomes from commissioning of the controls include:
1
Implemented direct reclaim rate control enabled improved responsiveness of TLO controllers and blend compliance
- Medium reclaim rates increased by 12% with 44% decrease in variability
- Dynamic reclaim control to achieve rolling average blend compliance
2
Tighter reclaim rate control enabled higher train loadout speeds
- Loading times reduced by 11% (~427 person-hours/annum recovered)
3
Improved stockpile dozer efficiency and integrating control system functionality for compliance with NSW specific safety guidelines (MDG28)
- o Dozer requirement halved (~2,000 person-hours/annum recovered)
Read the Conference Paper
Mipac Senior Process Engineer Hans Liang presented the Narrabri Coal case study at the International Coal Preparation Congress (ICPC) on the Gold Coast in October 2023. To read the full conference paper, click on the link below.
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