Vulcan Materials Company, the nation’s largest producer of construction aggregates, a major producer of asphalt mix and concrete, and a leading producer of cement in Florida. Its Jacksonville-based Florida Rock division is a leading producer in the state of aggregates, ready-mixed concrete, concrete block, portland cement, and prestressed concrete. The company's cement finishing mill is located in Newberry, Fla.
With the constant challenge of providing the highest quality product, while reducing material and energy costs and meeting stringent environmental regulations, the company also strives to continually achieve process efficiencies and tighter control through its existing equipment and technology infrastructure. However, when faced with the limitations of a manual approach to optimizing its finishing circuit, the Florida Rock mill moved to automated process control with Pavilion Technologies, a Rockwell Automation company.
The facility sought Pavilion’s Cement Grinding Control and Optimization Solution as a way to truly optimize the finish mill process. Leveraging Pavilion’s Model Predictive Control (MPC) technology, the application continuously assesses current and predicted operational data, compares them to desired results, and computes new control targets to reduce process variability and improve overall performance.
Florida Rock worked with Pavilion and its ValueFirst customer engagement methodology. Through this process, the two companies identified numerous variables that can affect the production process and developed the controller to fully utilize the mill’s potential under existing system limitations. ValueFirst helped the customer identify the following objectives:
- Maintain product quality (Blaine and 325 mesh) within specifications;
- Reduce process variability and improve operational stability;
- Maximize fresh clinker feed rate subject to equipment constraints; and
- Reduce power consumption per ton of cement
Results for the finishing mill included a 7.6% increase in production, power consumption was reduced by 6.5%, and controller utilization exceeded 95%. Consistency in operations was improved and ROI was achieved on the Pavilion control application in one year.
While Florida Rock’s advanced control application has helped it run more consistently and efficiently—for longer time periods and with less manual input—personnel still recognized limitations with regards to Blaine, or average particle fineness measurement and its correlation to cement strength. Results from an in-house laboratory study showed one-day strength correlated more closely with key particle size parameters than it did with Blaine. The next logical step was to move to on-line particle size measurement.
The challenge of Blaine
Malvern Instruments installed their on-line Insitec Fineness Analyzer, a laser diffraction system that generates real-time particle size data. Measurements are rapid, generating up to four complete particle size distributions every second. All aspects of measurement are fully automated. The analyzer software facilitates integration with the Pavilion system and the plant’s control platform. Refining the control model to use these parameters was the final step in achieving fully automated monitoring and control.
The Florida Rock facility has achieved additional benefits from the Malvern Insitec analyzer working with Pavilion’s control application. Together, a 15.3% production increase has been gained as well as a 20.3% reduction in power consumption, based on full particle size distribution information. These process improvements built upon the increase already achieved with the Pavilion application alone. Other key benefits of this process include: 95%-plus controller utilization; improved consistency in operations; and ROI achieved in one year.