Excessive variability in the cement manufacturing process is one of the primary causes of the poor performance of cement operations. Chemical and physical variability can result in effects such as increased fuel consumption, reduced refractory life, increased production of off-specification material and over-grinding of cement, all of which lead to increased operating costs. This variability can arise at all stages of the cement manufacturing process - quarry, raw milling, pyro-processing and cement milling, and this variability can be in both the chemical and physical parameters. However, each of these parameters, and the size of variation, has a different impact upon the total overall variability.
Therefore CPI has developed a Variability Calculator which estimates total quality performance for each stage of the process. The calculation is based on the experience gained by CPI over many years and at many plants. By inputting the standard deviation of each of the chemical and physical parameters into the calculator, users can review their performance at each stage of the process, and therefore review at what stage, if any, costly variability is being introduced.
Once the stage of the process where the variability is being introduced has been identified, CPI can then assist in reviewing the exact parameter(s) which is causing the variability and propose solutions to eliminate the variability and thus improve performance.
Which parameter to test?Cement - variability at this stage will impact the final product quality seen by the customer. The modern customer demands consistency as well as final product strength. Using the cement calculator will indicate the overall variability that the customer sees in your product.
Clinker - variability at the pyroprocessing stage can come from chemical variation or process instability such as flames, cooler operation and preheater tower efficiency. This will lead to a variable product for the cement milling stage and also sub-optimal process performance.
Raw meal - variability at the kiln feed stage can come from areas such as the quarry, dosing equipment and sub-optimal milling. The resultant variability will have an impact not only on the pyroprocessing section but also the efficiency of the raw milling process.
The results from the Variability Calculator are indicative only; they are based on CPI experience and are not absolute indicators of performance. The results are as a guide only and CPI can provide specific assistance to clients through their Process and Quality Improvement Services. Furthermore the quality of the results is dependent upon the reliability of the data input to the calculator.
