Robust Raw Mill Fan at Dunbar

Cement plants form a challenging environment for rotating equipment.

Significant amounts of silica dust occur as a by-product of certain construction processes. Over time this dust subjects rotating equipment, including Raw Mill fans, to high levels of erosion which ultimately reduces the plant’s output over time.

At Tarmac (Dunbar, UK), their existing Raw Mill fan was replaced with an enhanced Howden design in 2007. This Howden fan was specifically designed to handle the high silica dust burden that Tarmac face in their Dunbar plant. Over the past 12 years it has been performing to the highest of standards with only minimal outage repairs.


Installed in 2006, the original Raw Mill fan began to show signs of heavy erosion within the year. High silica dust caused wear on the fan blades adversely affecting the performance of the fan, and as a direct consequence, reducing the plant’s output significantly.

Due to the rotor needing to be replaced every six months the plant incurred high running and maintenance costs - and ultimately these rotor changes were just a  quick fix for the cement plant, rather than a permanent long term solution.

Tarmac decided a new, reliable, and efficient fan was required to handle the levels of erosion. That’s when Howden was invited by Tarmac to develop a solution.


With an extensive installed base within the cement market, Howden has gained considerable process experience in plants throughout the world. We offer expert and unbiased advice that is about finding the right solution for each application. Contact Us Today.


Technical experts from Howden, along with Tarmac’s operations team, developed a solution that best suited the operating conditions and process requirements of the plant.

After an in-depth study of the client’s environment, technical specifications, and a measurement campaign on-site, Howden and Tarmac were able to opt for a new fan - one that delivers a hard surfacing material and a scalloped center plate. This design limits the wear and significantly improves the lifespan of the fan by reducing the high erosion rate caused by the silica dust.


Whether it is supplying a new fan or retrofitting any of your existing fans, Howden has a solution for you - Check out our various types of fans.


Within seven days Howden commissioned and installed the new fan into the plant in late 2007. A highly efficient fan that copes effortlessly with even the most dust and particulate-laden processes that the Dunbar site faces.

The seamless collaboration between the on-site Howden staff and Tarmac teams, and the efficient manner in which they worked, made this short installation time possible.


Howden achieved what Tarmac had set out for them to do - they produced a solution that solved their issue of erosion, reducing maintenance requirements and costs, and increasing overall performance.

12 years on the fan continues to perform at the highest standard with only minor repairs needing to be carried out during the plant’s annual shutdowns.

Howden continues to support and partner Tarmac by providing local support from our UK service teams ensuring a fast, professional response. Technical expert support is provided from our cement centre of excellence located in Chalon-sur-Saône, France.


Complete the form to download the case study on how Howden helped Tarmac overcome fan erosion

Danbar Cement Plant in operation

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