Abstract
The Sasol Coal Value Chain is a complex system consisting of blending, stacking and reclaiming of no fewer than six different coal sources with vastly different coal qualities. The amount and quality of the gas produced from coal depend crucially on the quality of the coal reclaimed from the coal stacking yards. In this paper the development of a real time coal quality simulation model using information from an online X-Ray Fluorescence analyser, integrated with various data sources from the Coal Supply Facility, is presented. The integration of different data sources is discussed to create a centralised and standardised data framework for input to the simulation model. The simulation of a heap profile of the coal quality for each heap stacked, together with the quality of the reclaimed coal, is discussed in detail. It is shown how the generated information from the model is utilised in the development of a reclaiming strategy.
Highlights
If the data are used as is, and just broken up into smaller time buckets, the coal tons will be constant for long periods, which will lead to much less variability in the simulated reclaimed coal properties compared to the actual reclaimed coal
A stacker simulation model was developed in-house and implemented on the commercial plant to predict the properties of the heaps on all the stack yards
The stacker simulation model allows for the prediction of coal properties over the length of the heap, as well as the average ash percentage and standard error of the ash percentage for the heap
Summary
Given that ash content is the main coal property being monitored, having real time information available during stacking and reclaiming would significantly improve the planning and blending of the coal sources for delivering coal with desired quality and stability to the factory. An on-line X-Ray Fluorescence (XRF) analyser was installed on one stacker conveyor belt to provide real time information on the ash content and ash composition of the coal. The model utilises the on-line XRF data to calculate and to provide real time information on the ash content of the coal stacked across the length of the heap, and to calculate the ash content of the coal blends on the heaps as it is reclaimed. The stacking simulation model is an enabler for the online XRF data to improve the coal sources blending, and to deliver stable feed with desired quality to the factory. Note the calibration is performed on run-of-mine coal samples which ensures that the results are robust
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