India’s biggest OK™ mill – A story of reliable operations and smoother performance

March 17, 2017

Operations at OCL cement plant at Midnapore, India have been boosted by the successful commissioning of an OK 42-4 cement mill. Featuring the largest separator ever supplied by FLSmidth, the mill has met or exceeded all grinding circuit performance guarantees.

Infrastructure development is gathering pace in the Bengal region of India, which is driving local demand for cement. As one of the leading cement producers in eastern India, OCL India Limited (OCL) chose to respond to this demand by building a new cement plant at Midnapore, West Bengal. Productivity of the new plant, Bengal Cement Works, was high on OCL’s agenda and a grinding mill was seen as a crucial factor. So OCL went about sourcing a high-performing grinding mill, setting tough demands for the specifications, including outstanding separation capabilities and low energy consumption as well as guaranteed output levels.

OCL chose FLSmidth’s OK™ 42-4 vertical roller mill for its new cement grinding unit in Midnapore. The OK™ mill is the only vertical roller mill specifically designed for cement and slag grinding. Its unique design includes many patented features and proven components that make it the most efficient cement and slag mill available. OCL’s mill is equipped with added features to accommodate the plant’s specific requirements.

These features include:

  • A twin inlet feed chute for handling dry and high moisture feed materials without plugging
  • A separate dry fly ash feeding system for grinding Portland Pozzolana Cement (PPC)
  • FLSmidth’s proven iron removal system, which minimises wear during grinding of Portland Slag Cement (PSC)

The performance guarantees achieved at Midnapore within capacity, fineness and specific power consumption are typical of the best-in-class-performance of the FLSmidth OK™ mill. OCL’s mill produces 212 tph of PSC at 3800 cm2/gm Blaine without the use of grinding aid. Under these conditions, the mill area power consumption was 35.2 kWh/tonnes. Furthermore, OCL’s OK™ 42-4 has proven to be very flexible in adjusting to changes in the feed composition and granulometry. OCL grinds both PSC and PPC and the mill has demonstrated a seamless ability to accommodate changes to product type within minutes.

Large ROKSH separator
This OK™ 42-4 mill includes the latest version of FLSmidth’s ROKSH separator. Setting new standards for OK™ mill separators, the ROKSH separator is the most efficient cement vertical roller mill separator available. It features extremely low power consumption, low wear, and one of the most durable ‘top seals’ in the market.

Biggest gearbox supplied by FLSmidth MAAG® in India
Driving the OK™ vertical roller mill requires a robust gearbox with all the necessary power and reliability, and the FLSmidth MAAG® WPV 4000 gearbox was the best choice for the task. With a rated power of 6500 KW, this gearbox was one of the biggest and first of its kind in India. The WPV 4000 is a three-stage planetary gearbox with one bevel stage and two planetary stages and is equipped with an online condition monitoring system to ensure high reliability and availability. The planetary stage's load distribution is based on a 70-30 ratio.

Scope of supply 
The scope of the project included all major equipment, from fly ash storage to cement grinding. The vertical roller mill was of the type OK™ 42-4 with an ROKSH 108 separator. Its production was guaranteed at 212tph PSC at a power consumption of 39.3 KWH/T.

Achieving increased productivity with lower energy consumption, OCL in India sets new standards in grinding capacity with the largest OK mill in India. The performance guarantee tests of the OKTM 42-4 cement mill left OCL India Ltd highly satisfied.

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