Vertical Roller Mills for Finish Grinding

Ball mills, that are commonly used for finish grinding, have high energy demands, consuming up to 30-42 kWh/t clinker depending on the fineness of the cement. Complete replacement of ball mills by vertical roller mills (VRMs) with an integral separator – as opposed to the use of VRMs as pre-grinding to ball mills – is regarded as a breakthrough. Use of VRM in finish grinding combines grinding and high efficiency classification and improves both energy efficiency and productivity.

Energy efficiencies of ball mills and vertical roller mills

Source: FLSmith (as appeared in Harder, 2010)

Chinese flag According to MIIT of China, instability of material bed, vibration in the mill mill, serious wear of grinding roller and grinding disc, and product quality issues can be encountered when VRMs are used for finish grinding, and further improvements in these areas are necessary. This technology is considered to be suitable for new installations as well as for those undertaking major upgrades. The penetration rate of this technology in Chinese market is reported to be 5% in 2012. This figure is expected to reach 30% during the twelfth five-year development period. Plants interested in this technology are advised to carefully consider logistical aspects of maintenance and parts replacement by technology providers.  (MIIT, 2012. pp.26-27).

Development Status Products
Commercial
Cement

Vertical Roller Mills for Finish GrindingCosts & Benefits

Parent Process: Finish Grinding
Energy Savings Potential

Energy savings enabled by replacing ball mills with VRMs can be 20 to 30% and is primarily a function of the product fineness. 

Electricity consumption can be reduced by 10-24 kWh/ton of cement.

Indian flag Savings in the range of 20-24 kWh/t clinker are reported from India, depending on clinker  grindiability and product blaine.

Indian flag It is reported that vertical pregrinder can typical increse the capacity by 30%, and provide power saving in the range of 15-25% in the Indian context. 

Chinese flag  In China, replacement of ball mills with vertical roller mills in finish grinding can reduce energy consumption by 10 to 15 kWh/t-cement, representing a saving between 30 to 40% (MIIT, 2012. p. 26).

Chinese flag Using VRM in finish grinding, Hubei Yadong Cement Co, Ltd. achieved capacities and unit energy consumption values of 217.5 t/h and 30 kWh/t in producing of Grade P.O 42.5 cement and, 199.7 t/h and 34 kWh/t in producing grade P.C 32.5 cement (MIIT, 2012. p.27).

Chinese flag The electricity consumption of the main engine, the separator, and the fan of TRM45.4 finish vertical roller grinding system developed by Tianjin cement industry Design and Research Institute is reported to be between 18 ~ 22kWh/t-cement, 0.3 kWh/t-cement, and 9 kWh/t-cement respectively. Power consumption of this system is reported to be 4~6 kWh/t lower than that of combined grinding system with roller press and ball mill, and 10~15 kWh/t lower than that of ball mill system. This technology was successfully applied in Fukuyama Cement Corporation in Vietnam, producing better quality products and eliminating the need to use water and grinding aids (MIIT, 2012. p. 27).

CO2 Emission Reduction Potential

Chinese flag In the Chinese context, CO2 emissions can be reduced by 7.9 to 19 kg/t-cement with the use  of this technology. 

Indian flag In the Indian context, CO2 emissions can be reduced by 8.1 to 19.4 kg/t-cement with the use  of this technology. 

Costs

Investment costs are estimated to be between US $2.5 - 8 per annual ton cement capacity. 

Indian flag For India invesments in the range of $10-15 million, or US  $40-$65 per ton of hourly capacity are reported. 

Parent Process:
Energy Savings Potential
CO2 Emission Reduction Potential

N/A

Costs

Vertical Roller Mills for Finish Grinding Publications

Energy Efficiency Improvement Opportunities for the Cement Industry

The U.S. Environmental Protection Agency’s (EPA) energy guide, Energy Efficiency Improvement and Cost Saving Opportunities for Cement Making, discusses energy efficiency practices and technologies that can be implemented in cement manufacturing plants. This ENERGY STAR guide provides current real world examples of cement plants saving energy and reducing cost and carbon dioxide emissions.

Page Number: 

19-20

Development of State of the Art Techniques in Cement Manufacturing: Trying to Look Ahead

The report represents the independent research efforts of the European Cement Research Academy (ECRA) to identify, describe and evaluate technologies which may contribute to increase energy efficiency and to reduce greenhouse gas emissions from global cement production today as well as in the medium and long-term future. 

Page Number: 

54-55

Page Number: 

51-53

Advanced and Applicable Technology Guide for Energy Saving and Emission Reduction in Building Materials Industry (first batch)

Published jointly by the Chinese Ministry of Industry and Information Technology, Ministry of Science and Technology, and Ministry of Finance, this guide describes information on currently available as well as developing technologies that can help reduce energy consumption and emissions in building materials industries. The guide aims to inform decision makers involved with designing new plants and/or implementing energy efficiency and emission reduction projects in existing plants.

Page Number: 

26-27