Ball Mill Revamping

1.ProjectDescription

Project Title: Ball Mill Revamping

Contractor: Megaload Private Limited

Client: Tata Steel Limited ,  Jamshedpur , Jharkhand

Project Scope: Revamping of two 450-ton ball mills, including removal of the old ball mills and installation of new ones.

2. Project Background

The ball mills are crucial for the plant’s production, and their revamping was essential tomaintain efficiency and productivity. The old ball mill had to be replaced with a new one toensure optimal operations.

Precise Engineering:
The project involves precise engineering to handle the significant weight and size of the ball mills. Customization of the tower system is required to meet the specific site equirements.

Contract Award:

Megaload Private Limited was awarded the contract for revamping two 450-ton ballmills by Tata Steel Jamshedpur.

Weight of Each Ball Mill:
450 tons each

Execution Team:

Our dedicated team successfully managed the lifting, lowering, and shifting of the old ball mill and the subsequent shifting, lifting, and erection of the new ball mill. This was achieved using a tower system, strand jack system, and Self-Propelled Modular Transporter (SPMT) for shifting the old mill from the plant area to the fabrication area and the new ball mill from the fabrication area to the plant area under the strand jack system. This extraordinary feat reflects our commitment to handling substantial projects with precision and expertise.

3. Project Challenges

a. Time Constraint:
The customer provided a 108-hour shutdown period for the removal of the old ball mill and the erection of the new one. Since the entire plant’s production depended on this project, Megaload had to complete the entire operation within the stipulated time.

b. Space Constraint:
There was limited space in the existing running ball mill plant for the erection of the tower system.

c. Safety Precautions:. The erection of a high-capacity tower/strand jack system in a running plant required extraordinary safety precautions.
. Workers had to operate in a dusty environment, necessitating additional safety gear for their health and safety.

4. Girder Beam Erection:

Erecting a 32-meter-long span main girder beam weighing 65 tons posed a challenge because the existing EOT crane capacity was only 35 tons.
Megaload’s engineering team devised a solution by dividing the girder into two parts and providing an auxiliary tower with working platforms on one side for the first main girder beam assembly and connection, and a cantilever system with working platforms on the other side for the second girder beam assembly and connection.

5. Tower Foundation:

. Since the plant was old and the customer was not ready to cast a new tower foundation, Megaload installed towers on the existing foundation by providing different types of anchor bolts.
. The existing ground bearing capacity was not sufficient to take the load, so Megaload provided a 210mm thick, 6-meter-long by 2-meter-wide MS slab to spread the load among the existing foundation.
. The MS slab was secured with locking beams connected to the anchor bolts grouted in the existing foundation.

6. Ball Mill Dismantling:

Due to space constraints, it was not feasible to dismantle the 12-meter-long ball mill in one piece. Megaload provided a flexible tower system to address this challenge.

4. Sequence of Operation After Readiness of Tower System and Major Shutdown:

a. Sling Wrapping:
Huge capacity slings were wrapped around the ball mill surface, with ends
connected to four 180-ton capacity strand jacks.

b. Load Testing:
The load was taken on all four strand jacks. The old mill was lifted by 100mm from the existing foundation and held for one hour for load testing, which was certified by a competent person.

c. Lifting Old Mill:
After satisfactory clearance from a third-party inspection agency, Megaload started lifting the old mill to the required clearance of 1800mm.

d. Skidding Operation:
After successfully lifting the old mill to the required height, Megaload operators started skidding the ball mill using pulling strand jacks with precise load calculations. The skidding operation had to be precise to prevent any swing of the 450-ton old ball mill.

f. Lowering Old Mill:
After a successful 25-meter skidding operation, the old mill was lowered using four 180-ton strand jacks onto 24 SPMT axle lines below.

g. Disconnecting Slings:
The slings were disconnected from the old ball mill.

h. Tower Arrangement Removal:
The front side tower arrangement was removed along with the dismantling of one main girder beam to provide space for shifting the old mill from the plant area to the fabrication yard.

j. Shifting Old Mill:
The SPMT team started shifting the old mill, maneuvering in limited space.

k. Shifting New Ball Mill:
The SPMT was then shifted under the new ball mill, which was loaded and shifted to the lifting location.

l. Lifting New Ball Mill:
The new ball mill was lifted using four 180-ton strand jacks and skidded 25 meters to the foundation.

m. Lowering New Ball Mill:
The new ball mill was precisely lowered into the foundation with a 5mm gap, ensuring alignment.

n. Mechanical and Electrical Connections:
After successful lowering, the new ball mill was handed over to the mechanical team for their mechanical and electrical connections.

o. Dismantling Equipment:
Megaload started dismantling the tower/strand jack arrangement.

p. Completion:
The total shutdown time was 108 hours for the removal of the old mill and the erection of the new mill, and Megaload successfully completed the entire operation within the stipulated time.

5. Project Outcome

. The first unit of the ball mill was successfully completed within the stipulated time period, and production resumed smoothly.
. The second ball mill revamping is planned for December 2024.