Making history at Ste. Genevieve

The 30 January 2006 is a day to remember. This was the day FLSmidth signed a multi-million dollar contract with Holcim (US) Inc. to supply engineering, equipment and services for the world’s largest single kiln clinker production facility.

Construction of the state-of-the-art greenfield project in Ste. Genevieve County, Missouri, was completed in July 2009. And within its first three months of accumulated operation, the massive plant was breaking world records. On 21 November 2009, Ste. Genevieve’s kiln clinker production reached 13,160 tonnes per day (tpd) – becoming the first single kiln production line to break 13,000 tpd.

First-class design and engineering
At the start of the project, a core team of engineers from FLSmidth’s US office were assigned to the project fulltime. As the project escalated, new team members joined to help coordinate work between the different engineering disciplines within FLSmidth, and with the equipment ven-dors and the civil and structural designers. By the time the project had reached peak activity levels – during the engineering phase – the team had increased tenfold, working across three time zones, with our Copenhagen and Chennai offices providing personnel, technical expertise and resources as needed.

With many different companies involved in the plant design, FLSmidth’s web portal, MyFLS, was essential for distributing design documents between Holcim, its main contractor and the engineering firms engaged by FLSmidth.

Site preparation
Before the construction phase could get underway, the 3,900-acre site had to be levelled. Extensive excavation of rock created flat areas to accommodate the plant structures and ancillary systems; but not all natural features were flattened. In the primary crushing area, the natural terrain was incorporated into the structural design as a large notch was cut into the side of the mountain to house the crushing structure.

Designing for a river with extreme fluctuations
Thanks to its location on the banks of the Mississippi River – the largest river system in the United States – the plant has its own harbor. The harbor is approximately 116 metres wide and 305 metres long. To accommodate seasonal water level changes of up to 16 metres, the harbor houses several mooring structures and floating deck barges to ensure Holcim can load and unload all year round.

The river’s fluctuations also called for an unconventional conveyor belt design for offloading raw materials used in the process such as coal, petcoke and gypsum. The conveyor is mounted on a floating barge at its feed end while it discharges onto another belt on land. So that loading can be accommodated year round, despite river conditions, the belt is pinned at its head end and allowed to pivot and rotate at the feed end.

The project schedule included critical engineering and equipment deliverable milestones that afforded Holcim every opportunity to engage construction contractors as early as possible on this greenfield project. But on-site storage and real estate for preassembly were at a premium, so Holcim took delivery of major components on-site and used off-site locations along the Mississippi River – one in Memphis, Tennessee, and another in Cape Girardeau, Missouri – to assemble fabricated components and equipment, such as process dust collectors, preheater vessels and cyclones. These enormous structures were difficult to transport by road, and in some instances, impossible. But a pier constructed at the harbor’s east bank meant that large equip- ment could be delivered by barge on a just-in-time basis, which was a great asset for logistics planning.

Civil and structural design challenges
An enormous facility, the civil and structural design presented a number of challenges for both FLSmidth and Holcim. The plant’s structural foundations are supported by rock, but the plant is close to the 240 kilometre-long New Madrid fault line – and so exposed to seismic activity. To help resist seismic load, many of the plant’s structural foundations are connected to the rock with rock anchors, which resist both seismic uplift and wind load.

In three areas, the rock was not strong enough to bear the foundations. To overcome this problem, caissons were drilled between the preheater/pre-calciner and cooler structures, between the clinker storage silos and cement mills, as well as in the harbor area.

The hybrid preheater design also posed con- siderable layout and design challenges for the structural engineers. The plant’s process design dictated the preheater tower’s vessel layout, which meant that interior columns could not be placed throughout the structure for support. Instead, long-span deep girders were used for supporting all main levels. In addition, because rectangular support framing could not be used in all cases, skewed girders had to be incorp-orated into the design, further complicating the design process.

The impressive preheater structure consists of 12 perimeter columns with deep girders spanning between the columns on the seven floors that support major equipment. Steel framing was used to fill in the space between the girders and to construct minor access platforms, while reinforced concrete floor slabs were used on the main floors.

After construction workers had erected more than 30,000 tonnes of structural steel, poured more than 58,870 m3 (77,000 CY) of concrete, laid almost 43 km (140,000 LF) of process and utility piping, pulled 1,372 km (4.5 million LF) of cable, moved more than 28,000 tonnes of equipment, and clocked nearly 7 million man-hours, the plant was ready for operation.

Commissioning and performance
Construction officially began after a ground- breaking ceremony in March 2006, and the plant produced its first clinker in July 2009, almost 27 months later.

Extensive dry commissioning meant that almost all plant equipment reached full production within the first month after start-up. The operation sequence began when primary crusher came on line in November 2008; two cement mills came online in May 2009, followed by the raw mills in June and first clinker in early July.

After two months of accumulated run time, clinker production reached 12,000 tpd. In October, the plant’s availability rating reached an impressive 99.6 percent. Kiln operation was very stable during the start up phase, and the clinker quality met or exceeded Holcim’s requirements.

On 21 November 2009, Ste. Genevieve broke its first world record when clinker production reached 13,160 tpd. The first single kiln production line to break the seemingly impossible 13,000 tpd production barrier, this date will be one to remember for FLSmidth, Holcim and Ste. Genevieve.