Specific coal quality and stable calorific value are most important for processes using coal as a fuel or input material. The system of coal quality management is a complex of technologic and operational arrangements which aim at producing of required coal quality for certain application. It should be able to react on dynamic coal quality fluctuations in order to maintain the product quality requirements. High efficiency of the coal quality management is usually reached by combined implementation into several stages of the coal treatment process.
Systems of operational control
It is possible to affect the technology procedures using the effective system of operational control in order to achieve the required coal quality. The systems of operational control differ based on the facility type and the possibilities of existing equipment. The system includes not only the technical features but also the operational and decision-making rules. The operators of the functional blocks take care of the technology operation including the online measurement results, actual balances per time segment and the requirements on final product. This gives them the opportunity to take eventual actions to reach the goals of production.
Coal excavation control
In the open-pit mines the excavation is usually planned based on the geological survey maps. The real coal quality in individual coal seams can significantly differ.
The efficient excavation control can stabilize the quality of produced coal which reduces the costs of consequent coal cleaning or further homogenization.
Installing the on-line ashmeters directly on the excavators allows to verify whether the excavated coal quality conforms to the expected parameters and to adjust the excavation planning for the machines within the mine. The on-line measurement result is also displayed for the machine operator which can prevent from unwanted excavation of overburden.
The main operator puts the requests on excavator operation based on the excavation plan and the data from the on-line analyzers.
The coal is being blended during the transport from the machines. The on-line quality measurement at the output of the mine verifies the conformity with the plans and customer requirements.
It is complicated to install the on-line analyzers onto the mining machines in the underground mine. For the excavation controlling, there are used the on-line data on coal quality from different sections of the mine. The final quality is verified at the output of the mine during expedition. The on-line analyzers are mainly used in the technology on the ground but Enelex also offers ashmeters for underground explosive environment.
Coal processing plants
Ledvice coal washery | Czech Republic
The Ledvice coal washery receives coal from two local mines and sells to various customers. The coal is transported from the mines by belt conveyors and processed at the plant:
- ROM coal crushed and sorted by size
- Low grade coal used in local power plant without washing
- Washable coal treated by 4 washing lines
- Midlings blended with low-grade coal for utilization on power station
- Washed coal of different classes selling to coal traders and small power plants
Online analysis and CQMS is fully implemented to monitor the inputs and final product and to control the technology of washing and blending.
CQMS equipment:
- 29 online ashmeters
- 10 automatic samplers
- 4 in-service ashmeters
Coal stockyards
The coal homogenization process at the stockyards can achieve high stability of final product parameters according to specific requirements.
Based on on-line measurement of input coal quality fluctuations it is possible to control the stacking at the stockyard.
The mapping system of the coal quality at the stockpile layers is used for coal homogenization. The quality of the coal being stacked is measured by the on-line ashmeters mounted on the stacking machines. The sensors of machine and boom position are installed to determine the exact position of coal stacking and the information is recorded into the system together with data from on-line analysis.
The balances of stockpile contents are calculated on-line and compared to required quality enabling to adjust the further stacking of next layers and to reach the intended coal quality within the pile. The resulting coal quality is then verified by sampling and on-line measurement at the stockyard output.
