Plant report - Ste Genevieve - LafargeHolcim’s technological marvel

The LafargeHolcim cement plant in Ste Genevieve County, Missouri, US, boasts one of the largest single cement production lines in the world, with a capacity of approximately 12,000t/day. Its excellent limestone reserves and location directly on the Mississippi River enable it to produce vast quantities of cement at low cost for distribution over the majority of the eastern United States. Global Cement recently spoke to the plant’s manager John Goetz about this mega-plant ahead of the visit by delegates of the 61st IEEE-IAS/PCA Cement Industry Technical Conference on 2 May 2019...

Global Cement (GC): Please could you outline the history of the Ste Genevieve plant?

John Goetz (JG) - Plant Manager: I first became aware that the Ste Genevieve plant was being conceptualised when I was working at the Holcim Dundee plant in 2000. The location in Ste Genevieve County provided the most amazing quality limestone over thousands of hectares with easy access to the Mississippi River. The plant is uniquely located on the Mississippi below the last lock at St Louis, enabling it to provide cement over an unusually large portion of the United States. The concept of the plant from a design perspective is that it can produce a very large volume of cement at a very low cost, which makes it economical to provide cement over a wide region.

Around 5Mm³ of rock and soil had to be excavated before construction could begin in 2006. Most of the plant equipment arrived via the Mississippi River, which was helpful for this fairly congested site. The major structures were completed in 2007 and 2008, with first crushing in December 2008 and first clinker on 4 July 2009.

GC: Could you please describe the production process at the plant?

JG: All of the limestone is mined from the plant’s extensive captive quarry, which has reserves for more than 100 years of production. The high-quality limestone is blasted by an external contractor and then a fleet of Holcim-owned Komatsu front-end loaders and 100t haul trucks move material to the primary crusher, a 2000t/hr FLSmidth Mineral FFE gyratory crusher. A secondary crusher reduces material to <150mm for storage in the plant’s 65,000t Temcor aluminium dome. Within the dome is a stacker-reclaimer, which is from FLSmidth MVT.

After combining the limestone with correctives from our 350m secondary materials storage building, there is a single combined raw-mill feed system for two 515t/hr vertical roller mills from FLSmidth. Then there are two 15,000t FLSmidth CF silos for raw meal, which is introduced to the kiln system via FLSmidth Pfister feeders and via an Aumund belt bucket-elevator system. The preheater is a Holcim patented two-string hybrid tower that consists of four quad cyclone stages and a final dual cyclone in the fifth stage. It’s truly a technological marvel, with a total of 18 cyclones and a 10m-diameter calciner, and a retention time of around seven seconds. The efficiencies driven by the design, which I believe is unique in the world, provide unparalleled energy efficiency, very low emissions and economies of scale that are not matched anywhere else in the United States. Indeed, I’m fairly confident that Ste Genevieve is the largest kiln in operation today anywhere in the world and it continues to out-perform our expectations on every front.

The tower is fired by a low-NO_x calciner from FLSmidth and the three-support rotary kiln by a FLSmidth Duoflex burner. Following the kiln, the clinker goes through an IKN cooler. Clinker grinding is carried out using four FLSmidth OK 36.4 vertical roller mills and transferred to the cement storage systems for truck, rail and barge distribution.

Above: List of equipment installed at the Ste Genevieve cement plant in Ste Genevieve County, Missouri, US.

GC: Have there been any changes since the plant began production in 2009?

JG: The manufacturing process is essentially unchanged with the one exception of the replacement of the clinker cooler in 2014 with a new IKN cooler. However, we continue to learn about the process and optimise the plant towards its full potential. Energy efficiency improvements have been achieved every year since startup and the last couple years have set many production and cost records for the history of the plant. That counts from the quarry to the harbour.
We continue to improve upon the process and the plant’s ingrained advantages, especially on the fronts of environmental performance and energy efficiency. I don’t want to comment quantitatively, but I can say that I know of no other plant that operates at such a low specific thermal and electrical consumption per tonne of cement. Our CO₂ emissions are more than 20% below the US average per tonne of cement.

Another small change is that we have now started the process of rehabilitating the quarry where we no longer require access to it. This has occurred over the past two years or so.

GC: Where do the plant’s additives come from?

JG: Today we source gypsum, silica, alumina and iron correctives economically from a variety of sources across the vast river network. At the moment we bring in materials from as far north as Chicago to as far south as the Tennessee River Valley via truck or barge. We work in partnership with a number of industrial and power-generating companies to assist them with management of waste streams, which we safely incorporate into the cement manufacturing process. This is one of the main drivers of our ability to produce cement at very low cost.

GC: What about fuels?

JG: The plant currently uses traditional fuels, namely coal and petcoke. Since its inception, access to coal and petcoke have been extremely economical and remain the central fuels used at the plant.

GC: Could the plant use alternative fuels?

JG: The plant is designed to use a variety of alternative fuels. There are some liquid alternative fuels currently being used. They are sourced from a variety of places in a similar manner to the additives. We constantly look at opportunities to become more environmentally friendly and to reduce our CO₂ footprint. Fuel flexibility is a key component of our plant strategy. We continually review markets and market opportunities and are prepared to implement new fuels at the plant.

GC: What emissions abatement systems does the plant use?

JG: There is an ammonia-based SNCR system to control NO_x emissions, which has been used since the plant was first built. For dust we operate baghouses, which also remain unchanged since 2009. A new dry lime injection system was installed in 2016 replacing the wet lime injection system to help control SO₂.

I’d like to highlight that, over nearly 10 years of production the plant has never had a notice of violation (NOV), which is testament to the importance that the staff place on environmental protection.

GC: What types of cement are made at the plant?

JG: We make 100% low-alkali CEM I. It performs well in all of the markets that we cover. The coefficient of variation is consistently at or below 3.0. Our customers receive the same cement day-after-day, week-after-week, year-after-year. This is great for them from a quality perspective and great for the plant from a process perspective. This is because the plant is optimised to a very high degree. We don’t want to jeopardise that by changing the product.

GC: How do LafargeHolcim’s other plants fit into this approach?

JG: At the moment Ste Genevieve is pumping out CEM I and other plants make the other types of cement. That might not always be the case, but it is the group’s current strategy.

GC: To where does Ste Genevieve deliver its cement?

JG: Our product is shipped to 22 different US States, from Minnesota down to Texas, as far west as Nebraska and as far east as Pennsylvania. This is mainly thanks to the river system, although we also make use of extensive rail connections and also truck out some product. In 2018 we sent out 70% by barge, around 20% by rail and 10% by road. Those proportions have been fairly static for a number of years.

GC: What would you say is the largest threat to the plant over the next 1-5 years?

JG: This is a tricky question. I honestly don’t see any major threats to the plant. It is a unique facility that is well positioned to take on whatever may be thrown at it as the market changes. The plant offers us great opportunities.

GC: Would you not say that the ‘retirement time-bomb’ is something to worry about?

JG: If by ‘retirement time-bomb’ you mean that a significant portion of staff are heading towards retirement, giving rise to a staff shortage, that’s not something that is affecting this plant. We have a great local team and a strong development program that aligns with our internship programs for new engineers. All of this has led to a strong and experienced team which we are very proud to maintain.

GC: Has the merger between Lafarge and Holcim given rise to any day-to-day changes as you see it?

JG: What I would say is that, right from when I first started working for Holderbank, as it was back in 1992, until today, the LafargeHolcim Group has great core values based on its people, its customers, its performance and the environment. These values, plus great support from central management, have been retained throughout the merger and I see no reason why it would change now.

GC: John Goetz - Thank you for your time today.

JG: You are very welcome indeed!