- INTER GRINDING v/s SEPARATE GRINDING (PSC)
A trial was carried out at one of the grinding unitand based on the final dataof heat
and power consumption, it is evident that inter grinding is beneficial than Separate
grinding. The savings on heat, power and water consumption is tabulated here. Slight
increase in one-day strength is also recorded.
Case Study
PSC Cement Data Recorded by Plant Team D i ff e r e n c e
(Benefit in
Parameter UOM Separate inter grinding)
grindingInter
grinding
Sp. Power Consumption kwh/t of cement 30.65 29.7 0.95Sp. Fuel Consumption kcal/kg cement 94.45 76 18.45Sp. Water Consumption Liter/t of cement 10.2 6.94 3.26
1 day Strength MPa 8.33 9.1 0.77Finer grinding of Slag shall permit higher addition percentage of slag. Intergrinding
is recommended up to 3600 Blaine. For higher Blaineseparate grinding is recommended.
In case of roller press ball mill circuit, slag shall be ground in roller press in finish mode.
Since the hydrated clinker (which is easy to grind) was used during trial for separate
grinding of CCR so it is advised to conduct one set of trial ensuring similar clinker
and other raw materials for better clarity, however based on data of last trial and
experience it is clear to take decision on benefits of Inter grinding
Other benefits of Inter Grinding is given below
- Cement silos required are only for PSC/PCC grinding.
- Lesser space required, lesser project cost.
- No need to optimize the mill (Dam ring, Nozzle velocity, Separator RPM
& gas flow requirement) for various products like Slag and OPC. It can be
well optimized for one product i.e. PSC/PCC, which gives stable mill
operation and product quality consistency. - Product Blaine required is one, which leads in better mixing of clinker and
slag particles at same fineness gives better reactivity and strength. - Wear rate of mill internals in one product is gradual and uniform.
- No mixing equipment’s like blender is required.
Conclusion
Based on above Comparison Inter Grinding option for PSC & PCC is better.