Material analysis for process control in cement plants

1 Introduction

Online measuring methods are indispensable for process control in cement factories. However, while measurements of temperatures, pressures, filling levels, flow rates, motor powers and gas analysis parameters are long established, the online measurement of material parameters for process control purposes is far less common. This may be connected with the fact that ma­terial analysis has up to now mainly been regarded as an essential component of quality assurance systems. Furthermore, material analysis for non-online measurements is without doubt relatively complex and the route from the material sampling points via pneumatic delivery systems, material preparation devices and analysis up to the mixture control system is very long.

However, numerous inline measuring methods exist for elementary and phase analysis of the starting materials such as raw materials and fuels, intermediate products such as raw meal, hot meal and cement clinker and the various types of cement as finished products which can also be used for process control. The demands imposed on these result from quality and profitability objectives that can only be attained with more uniform and troublefree plant operation and simultaneous conservation of resources. However, the conservation of resources often runs counter to considerations of quality because it involves the use of poorer or more problematic raw material qualities and more complex secondary materials. Moreover, additional demands are imposed by the trend towards the production of a range of different types of cement.