Modernising the process at Mitchell

To meet contemporary goals of sustainability – as well as to increase capacity and meet current market demands – cement plant construction has evolved. When Lehigh Hanson (soon to be to be rebranded as Heidelberg Materials), began planning the construction of its new facility in Mitchell, Indiana, it became clear that the new plant would be a key tool in achieving the company’s high standards in improved energy efficiency and other key sustainability targets, both in its construction and its operation, while also accommodating modern production equipment and ensuring increased output.

“While we knew achieving these ambitious goals would be no easy task,” said Axel Conrads, Midwest Region President, “we are excited about tackling the challenges associated with building the most modernised and second-largest cement kiln in the United States.” The new facility will replace the existing plant and is anticipated to help ease construction supply chain issues by producing four times the amount of cement than was produced at the old facility, with total annual production expected to be 2.4 million t of cement.

The US$600 million+ modernisation project is taking place on the current Mitchell cement plant and terminal grounds, located in Lawrence County, Indiana, southwest of Indianapolis. The project represents the largest capital investment in the history of Heidelberg Materials, Lehigh Hanson’s global parent company. It is also one of the largest investments ever made in Lawrence County, making it a significant growth engine for the region. The plant is expected to provide approximately 50 new full-time jobs, going from 120 to over 170 full-time employees. The project has created new technical training and growth opportunities not only for these new positions but for the majority of plant employees as well.

The new facility represents major strides in the sustainability of cement production, in line with Heidelberg Materials’ global commitment to achieving an industry-leading 400 kg CO₂/t of cementitious material by 2030 and achieving carbon-neutral concrete by 2050 at the latest. Helping to meet the company’s ambitious sustainability goals facilitated a new approach to construction for the Mitchell site. Designers were faced with the task of reducing energy usage, fuel consumption, and emissions per ton of cement produced.

Fundamental to the plant’s sustainability is its adherence to the guidelines included in the Portland Cement Association (PCA) Roadmap to Carbon Neutrality. The plant will not only produce Portland-limestone cement (PLC), but PLC was used it in its own construction. Lehigh Hanson’s EcoCemPLC is a blended cement with as much as 10% more limestone content than ordinary Portland cement. It uses the same components and has the same yields as ASTM Type I-II/AASHTO Type I Portland cement and has equivalent performance, meeting ASTM C595 Type IL standards. And importantly, it has lower carbon intensity associated with cement production. EcoCemPLC is available in bulk and bag.

The existing plant operates ball mills for both raw materials and cement grinding, and the plant modernisation improves its sustainability even further due to the selection of vertical roller mills for grinding, creating a step change in the power consumption of the plant as measured by ton of product processed: when compared to the existing unit consumption, the new cement mills will be grinding each ton of similar products for less than 60% the current power usage.

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Read the article online at: https://www.worldcement.com/special-reports/09122022/modernising-the-process-at-mitchell/