VRM audits and optimisation
The increasing use of vertical roller mills (VRMs) in the production of cement to reduce power consumption and CO2 emissions has resulted in an increasing need for VRM optimisation. As cement producers look to protect profits as well as their environmental reputation, a process audit can identify the root causes of issues to help plan for improvements in power consumption and performance. By Anil Kumar Popuri, National Council for Cement and Building Materials, India.
Figure 1: measuring the distance between the end
of the grit cone and the grinding bowl (case study 1)
Cement production is a highly energy-intensive manufacturing process with energy consumption of 85-100kWh/t of cement – most of which is used by grinding operations. This high level of energy consumption, along with increasing cement demand and CO2 emissions, requires the use of efficient grinding technologies such as vertical roller mills (VRMs) to reduce the impact on profit margins as well as the environment.
VRMs are widely used in the cement industry, particularly for grinding coal, raw materials and clinker. Grinding takes place between the grinding table and the rollers by compression force. High-efficiency dynamic air classifiers inside the VRM separate sufficiently ground material from rejects that need to be re-introduced to the mill for further grinding. In addition, VRMs can also dry the material to be ground and, therefore, can handle material with a high moisture content.
