Potential Considerations for Effective Clinker Grinding
Clinker grinding is the final step of cement production. The cement production is done continuously due to the possibility of its storage as a clinker. On the contrary, clinker grinding is done only depending upon the demand for cement. The clinker usually consists of particles of up to 25 mm size which is stored safely for further processing as and when needed. Production of clinker is essential for the cement industry as it gives the manufacturer to keep the stock in the warehouses and process further when the demand rises. Let us look at various parameters involved in the process of clinker grinding:
· Size Reduction
The cement grinding process begins with crushing large pieces of raw material into clinker of size 25–20 mm. From this size, the clinker grinding process aims to achieve at least 80% of the particles ground to 3 to 30 microns size. The size reduction target for clinker grinding is fine as compared to the grinding target of clinker production.
· Equipment
Ball mills or vertical roller mills are widely used for clinker grinding. Since the goal is to achieve fine-sized particles, the ball mills used are bigger than those used for mineral processing plants. It is also important to operate ball mills at a speed of 15–20 revolutions per minute. The faster speeds result in the onset of centrifugal force which causes failure of crushing impact. Speed slower than this would not give the balls enough momentum to generate desired impact force. Ball mills are also operated for a long duration to achieve the required particle size. Lately, vertical roller mills have replaced ball mills due to higher energy efficiency.
· Energy Costs
It is estimated that nearly 70% energy cost involved in cement production is taken up by the crushing and grinding operations. This energy is divided between initial grinding steps before and after clinker production. The process of clinker production has a significant share in energy consumption. Therefore, an energy-efficient system is required for the production of cement from clinker. It is due to the energy-saving cost that vertical roller mills are being utilized by most of the cement manufacturers.
· Addition of Gypsum
When a clinker is fed into a ball mill or vertical roller mill, some amount of water is also added for the ease of cement production. However, the addition of water into the mixture can cause the cement to set immediately. This is problematic as it does not allow time for the complete processing of the cement. To avoid this, it is vital to add gypsum to the grinding mill which slows down the hydration process and allows for successful completion of the process.
Conclusion
Clinker grinding is a relatively less time-consuming process as compared to the rest of the cement production process. This is the sole reason for cement manufacturers to complete the process in an intermittent way. Despite this benefit, energy consumption remains high. Therefore, it is important to use proper equipment and follow specific guidelines for the effective production of cement from clinker.
