3D Image Reclaimer Control provides optimised control for bucketwheel reclaimers. Bucketwheel reclaimers are the most common type of reclaimer used in the coal and iron ore industries.
The 3D Image Reclaimer Control application offers improved reclaimer productivity and safety via a technological leap in sensors and software application.
The key component and differentiator of the controller is the use of 3D Image Time of Flight Sensors to provide accurate measurement of the reclaiming process.
A set of four cameras are positioned to measure the shape and volume of the stockpile bench face at the bucketwheel. The cameras measure at 30 frames per second to provide a combined 2.3 million 3D measurement points per second. Each 3D measurement point represents a 30mm x 30mm point on the bench face. Bucketwheel cut depth is measured with an accuracy of 20mm. The reclaim volume rate is calculated from the change in face volume with an accuracy of 2%.
The accurate bench face profile at the bucketwheel provides for pre-emptive reclaimer control.
3D Image Reclaimer Control incorporates the 3D Image Volume Rate Controller, referred to in this document as the Volume Rate Controller.
- Reclaim rate control is based on direct measurement of the reclaimed volume.
- The Volume Rate Controller replaces traditional implied (power/torque) based control systems to provide product independent reclaim rate control.
- The ability to accurately and dynamically measure the stockpile face volume immediately adjacent to the bucketwheel is the enabling technology for this control technique.
Slewing Bucketwheel Reclaimer
Volume Rate Controller
The Volume Rate Controller provides improved reclaimer performance in comparison to existing ‘State of the Art’ Implied Rate and Predictive Volume systems.
The Volume Rate Controller is a revolutionary approach to reclaim rate control and is NOT simply another attempt to improve the performance of existing power based control systems.
The Volume Rate Controller measures and controls the reclaimer production rate in terms of volume (cubic metres per second) by continuous high speed measurement of the stockpile volume at the bucketwheel.
Volume accuracy of better than 2% is achieved. The reclaim volume rate is measured as the rate at which the face volume is changing. Bench collapses and product flow result in change in the face shape but does not significantly alter the volume. Volume accuracy is not affected by stockpile shape, bench face collapses, product retention in the buckets or product thrown from the buckets. Accurate reclaim volume measurement is achieved by locating 3D imaging sensors on each side and immediately adjacent to the bucketwheel, orientated such that bench face area adjacent to the bucketwheel and the complete cutting arc of the bucketwheel is measured.
By providing accurate reclaim volume measurement the reclaim volume rate (m3/hr) becomes independent of the product characteristics, stockpile face shape and bucketwheel cutting characteristics.
Whilst measurement and calculation of the reclaim volume is complex, the application of the bucketwheel speed control is simplified as there is no longer any requirement to apply the customised correction parameters that are typically implemented in an attempt to improve the performance of power based controllers. Accurate measurement of the volume forward of the bucketwheel provides pre-emptive machine control, rather than the lagging control of power based controller.
The measured bench face shape is also used to provide improved machine safety and bucketwheel position control that operates in unison with the Volume Rate Controller to provided reclaimer performance improvements.
Objectives
Bucket-wheel reclaimers are a high cost mining asset. Individual machine cost may exceed $50M, with supporting stockyard infrastructure adding significant cost. Reclaimers represent an important link in the supply delivery chain. Relatively small improvement in reclaimer productivity will provide economic benefit to the business.
The objectives of 3D Image Reclaimer Control are:
- Increased production opportunity
- Improved reclaimer safety
- Stabilise route equipment loading
- Reduce reclaimer maintenance
- Reduces number of fatigue events on the machine
Production rate (Reclaim Rate) is the key performance indicator for bucketwheel reclaimers.
Previous projects have attempted to provide reclaim rate improvement by tuning the power based slew rate controller and implementing various conditional limits and product type compensation schemes.
Prior reclaimer control systems based on stockpile scanning still rely on inferred power/torque reclaim rate control, whilst the actual reclaim volume is still dependent on product type, stockpile shape and bucketwheel cut characteristics.
The differentiator is that, rather than using a theoretical (predicted) reclaim volume rate, the Volume Rate Controller accurately measures and controls.
- 3D Image Reclaimer Control provides a high sustainable Return on Investment
- 3D Image Reclaimer Control introduces the most significant development ever in reclaimer control
- 3D Image Reclaimer Control is the only system that measures and controls the reclaim volume (reclaimers are volume machines, not TPH)
- 3D Image Reclaimer Control provides optimal reclaimer performance, independent of product and stockpile state
- 3D image technology facilitates the use of new reclaiming techniques to provide previously unattainable improvement in reclaimer performance