Cement Energy & Environment

36 Fig-8: KHD SFM-S type circuit Fig-9: KHD SFM-B type circuit It is evident from some of the ball mill upgrade contracts that CAPEX is lower in comparison to new plants due to the following: • Existing feed hoppers can be utilised in most cases. For meeting the storage requirement of increased production figures, there can be necessity of max. one additional hopper for clinker. • Raw materials (clinker, gypsum, performance improver, slag and fly ash etc.) conveying arrangement can be retained as per the existing setup as the existing feed hoppers are used. Again, because of the increased production figures, there can be necessity of modifying the conveying capacities. • Product conveying arrangement is also much optimised with single product from the circuit. From operational point of view, it is noteworthy to mention the following advantages with ball mill upgrade circuits: • Production increase is always there and the amount increase can be up to 300%. This depends on existing ball mill size and the selected RP size. • Inefficiency of ball mill in terms of energy demand is compensated by adding energy efficient Roller Press in the circuit. Roller Press consumes electrical power around 50% of the ball mill for producing similar product. Overall saving in sp. power consumption can be from 3 kWh/t to 6 kWh/t depending on the cement type produced. • Inefficiency of old separators which are due for replacement is eliminated with new highly efficient separators. • Drying requirements of new products with high moist feed components like slag, wet fly ash are met with Roller Press circuits which was not possible with ball mill circuits. • Cooling requirement of very high clinker temperature without adding water spray is met with Roller Press circuits which was not possible with ball mill circuits. • There is flexibility of running RP in finish mode or semi finish mode. When there is less market cement demand, RP can be operated in finish mode without ball mill and resulting in less sp. power consumption. 4.0 UPGRADE OF BALL MILL WITH RP FOR CEMENT PRODUCTION ENHANCEMENT: CASE STUDY Since its inception in Dec 2000, KHD Humboldt Wedag India (HWI) secured and executed 23 ball mill upgrade contracts in India. Among these, major portion is from UltraTech Cement, largest cement producer in India. UltraTech cement had chosen this upgrade concept keeping in view of the CAPEX advantage, OPEX advantage and other operational flexibilities. And it became a major success. UltraTech Cement awarded 8 cement mill upgrade contracts to HWI in the last 3 years i.e., 5 upgrade contracts (Hirmi CM-1, Jharsuguda CM- 1, Sonar Bangla CM-2, Neem ka thana, Magdalla CM-1) in year 2021, 2 upgrade contracts (Roorkee, Arakkonam) in year 2022 and 1 upgrade contract (Nathdwara CM-3) in year 2023. Same Roller Press model (RP20-170/180) is selected for all these 8 upgrade contracts. One upgrade case study from UltraTech group is elaborated below to showcase the success.