Category: High Performance Concrete
St Marys Cement, part of the North American operations of international building materials supplier, Votorantim Cimentos, recently expanded and modernized its Charlevoix, MI plant. The most innovative use of slag cement on the project was the 23,000-ton blending silo. It holds enough raw feed for 2.5 days of production. It stands 160 feet tall and is 78 feet in diameter. It was poured in a continuous slip-form pour that lasted several days.
15% slag cement was utilized to control the set and strength gain of the concrete placement. It required the concrete to stay workable while it was placed into the forms. It also needed to gain strength quickly enough that the forms could be raised up to cast the next level. Slag cement helped create a concrete mix that allowed for the project’s unique placement requirements of extended workability and great strength gain.
The full scope of the plant modernization encompasses:
- a raw mill upgrade, modernized with an all-new 3900hp Dorol roller mill designed by Thyssenkrupp Industrial Solutions (TKIS) with a capacity of 445tph, and equipped with a new dynamic separator and dedusting cyclones. The mill circuit includes a new 5200hp system fan.
- an upgraded preheater/precalciner, designed by TKIS, modernized with the addition of a parallel four-stage string to the existing four-stage preheater tower, increasing the feed capacity by 40 per cent. A 1750hp induced-draught fan is included in the new preheater string.
- a new calciner, designed by TKIS, replaces the old flash furnace calciner, ensuring increased residence time to 7s at temperature while providing more efficient combustion and reducing plant emissions.
- a new 25,000t capacity tangential blending silo, designed by TKIS, to store and distribute the kiln feed, greatly improving quality control and reducing power consumption. The upgraded system replaces a 9000t kiln feed storage system.
- kiln modifications that increase capacity from 4250tpd to 6000tpd. The modified kiln is 5.2m in diameter and 73m long.
- a state-of-the-art Polytrack clinker cooler from TKIS, with technology and efficiencies that produce a cooler kiln product and enhance heat recovery.
- a new 6000hp cement ball mill rated at 120tph, designed by China-based TCDRI. Added to the existing three mills, it provides capacity to handle the overall production increases.
- a new 2700hp high-capacity coal mill rated at 38tph, designed by TCDRI. The plant operates on petcoke and coal, supplemented with five per cent shredded plastic that would otherwise end up in landfill.
- a new clinker transport conveyor to move clinker to the finish mills.
- a new cement transport gravity conveyor and elevator to move cement to the storage silos, installed with the new cement mill. The system provides an energy- and maintenance-efficient alternative to conventional pneumatic systems.
St Marys Plant Expansion Press:
Project Team: Owner: St. Marys Cement, Matthew Simon; Engineer: TCDRI; Contractor: Walbridge; Concrete: Manthei Development Corp, Joe Sladek; Slag Cement; St. Marys Cement, Chris Kennedy