Global Cement recently visited the Lafarge Cement Cauldon Plant, which is celebrating 60 years of continuous cement production, from 1957 to 2017. Lafarge Cement is part of Aggregate Industries, which is itself owned by LafargeHolcim. The compact Cauldon plant has a long and varied history and was the first dry-process cement plant in the UK. Here we take a tour of the plant - and its history - with Martin Bains, former plant manager.
Global Cement visited Cauldon in Staffordshire, in the very heart of England, on the very day that Martin Bains stepped down from his job as plant manager to move on to the LafargeHolcim Technical Centre in Lyon. Notwithstanding his move to ‘pastures new,’ Martin explained the history behind the plant and the reasons for its current somewhat unusual arrangement.
“It may not seem the boldest claim to say that Cauldon was Britain’s first dry process cement plant,” says Martin Bains, “but in fact, in its own way, it was a major step forward for the industry. After all, the efficiences and economies it achieved played a large part towards modernising the UK cement industry after World War Two. Although the founding of the plant which has grown into today’s business only dates back to 1957, the quarrying of limestone in the Cauldon Low area goes back several centuries before that.”
Cement manufacturing is both capital- and energy-intensive. The cost of building the Cauldon plant in 1957 was £3.5m, the equivalent of £80m (Euro88.3m) today, excluding land and other costs. When G&T Earle Ltd, Cauldon’s founding company, decided in the 1920s to build a new cement works in Derbyshire to use low-moisture limestone and shale as its raw materials, it had to be designed for the prevailing wet process. However, in 1928 in Germany, a new type of kiln had been invented which could operate on a ‘dry process’ basis, with the raw materials being fed in as dry pellets. The so-called ‘Lepol kiln’ was quite widespread in Germany by 1945 and the decision was taken to design the plant as a dry process works. Construction of the plant began in 1954 and the first clinker was produced in 1957. Outputs from the first three Lepol kilns were around 27t/hr of clinker, with heat consumption of around 900kCal/kg clinker, compared to the output of wet process kilns of the time of around 15 - 20t/hr clinker and a fuel consumption of around 1600kCal/kg clinker.”
Over 1982 - 85, the three Lepol kilns were replaced by one larger-capacity preheater-precalciner kiln, which now sits in the kiln ‘shed’ previously occupied by the three former kilns. As well as the traditional coal, Cauldon now obtains over 60% of its thermal energy from waste-derived fuels, such as chipped vehicle tyres, processed sewage pellets, liquid-derived fuels and recovered solids. Cauldon now produces around 0.96Mt/year of cement, which is nearly 10% of the cement used in Great Britain.”
Products and quality
Our team of technical experts ensures that our products are always manufactured to the highest standards and this fact is borne out by the third-party accreditation that our products carry. Of course, all of our cement products carry the CE Mark and they meet EN 197-1, the European standard for cement. We strive to work with the LafargeHolcim group to find solutions that tackle our customers’ everyday challenges, from achieving energy efficiency, lowering cost of construction, reducing our footprint and meeting high standards of aesthetics, health, comfort and well-being. From that standpoint, we have developed a market-leading range of quality bulk and packed cement products. Cauldon supplies a range of three cement types distributed through our five terminals. Portland Cement is a versatile grey CEM 1 52.5N cement, ideal for applications requiring good seven day and 28 day strengths. The cement is ideal for ready-mix and civil engineering applications, with good compatibility with admixtures and additives such as GGBS. Rapid Hardening Portland Cement is a high early strength CEM 1 52.5R cement that can be used when higher strengths are required, such as in precast and concrete products. This cement allows early demoulding of products for production efficiency. Finally Portland Fly Ash Cement is a low carbon footprint CEM 2/B-V 52.5N cement resistant to sulphate and chloride attack and which is suitable for the most aggressive ground conditions. This cement has a moderate heat of hydration for large concrete pours. We can also supply a full range of packed products including Lafarge Postmix and Lafarge General Purpose Cement.”
Raw materials
“Cauldon’s largest raw material requirement is for limestone, which is quarried from the limestone quarry south of the plant. Around 1.2Mt per year of limestone has be dug each year, and the equipment needed to compete the job has increased in size considerably over the years, from small trucks carrying 15t of stone in the 1950s, to today’s giants carrying 65t each.”
“Shale is the second most-used raw material, with around 200 - 220,000t of material quarried each year from land north and west of the plant. Unlike in the limestone quarry, shale is dug on a ‘campaign’ basis during the drier summer months. A shale stockpile is created near the factory and this is used to supply the factory’s needs throughout the year. Other raw materials are brought into the site, including gypsum, sand, pulverised fly ash and the variety of fuels used at the plant.”
“We have restored the land after it has been used. When Cauldon opened in 1957, the immediate surroundings of the plant were landscaped with tree planting and ‘gardening.’ When the shale supplies obtained from small and shallow quarries immediately west of the factory were quickly exhausted, the areas were landscaped and now host the Angling Club and a varied wildlife population. The first quarries north of the plant were also shallow, small and quickly completed, then restored. One now hosts the plant’s reedbed water treatment system. Shale mining then turned north-west of the plant, on the old Waterhouses railway line route. Here, the geology meant that the shale occurred at widely different depths, so it had to be worked as four separate quarry areas. The first area was very deep and has been allowed to flood to create an extensive, carefully landscaped lake, which now hosts a lot of wildlife. The next area, Area B, was extremely shallow and has been partly restored to species-rich grassland, with parts still in use for the storage of soils for later restoration. West across Lee Brook is Area C, which is still being quarried and is now developing northwards into Area D. Southern and south-western quarry steps here have already been landscaped, with extensive tree planting. When quarrying has been completed, Areas C and D will also become landscaped lakes teeming with wildlife. “
“The limestone quarry presents different challenges. Much larger than any of the shale quarries, its ultimate extent was almost completely bordered by new tree plantations in the 1970s which are now mature landscape features. Since 2008 the quarry has reached its maximum permitted extent to the south and extensive experiments have been undertaken to create the best conditions possible for wildlife diversity. Rollover slopes have been constructed, rather than the harsh angular quarry faces of yesteryear, so the restored landscape appears natural. A series of trials are in progress exploring how best to create bio-diverse limestone grassland and are already showing excellent results.”
Notably, over 40 bird species have been spotted in the quarry, on restored land and around the cement plant - a strong indicator of healthy biodiversity.
Environmental impacts
“Over the last 60 years, environmental standards and legislative requirements have changed beyond all recognition. Emission limits have become much tighter and Cauldon has had to adapt to new and higher standards. Since 1998, the industry has reduced nitrogen oxide emissions by 60% and particulate emissions have been reduced by up to 90%. Along with these requirements, more conventional environmental impacts such as noise, vibration, water pollution and traffic have also always needed attention.
When it opened in 1957, the factory used electrostatic precipitators to collect dust from the hot kiln gases, before it was discharged up the chimney to the atmosphere. Electrostatic precipitators were industry standard because they coped well with very hot gases. By the time that the new plant was built in the 1980s, materials capable of withstanding high temperatures had become available and, in due course, the gravel bed filter for the clinker cooler exhaust was replaced by a bag filter which was more efficient and reliable. In fact this is still the technology used today. Cement manufacturing now emits, on average, 0.22kg of dust per ton of cement, down from 0.37kg in 1998. At Cauldon prior to 2000, the limit on particulates from the chimney was 100mg/m3 of gas and Cauldon typically achieved 40-50mg/m3. Today it is less than 30mg/m3. The most significant changes in emissions over the years were on the smaller filters. The limits on particulates from the clinker cooler changed from 100mg/m3 to 10mg/m3 and from the cement mills from 50mg/m3 to 10mg/m3.
The replacement of some conventional fuels such as coal, oil or gas by substitute fuels such as chipped car tyres, processed sewage pellets, solid recovered fuel and waste-derived liquid fuel, also mean that cement is now far more economical to produce. Cauldon now meets over 60% of its heat requirement from waste-derived and solid recovered fuels. In February 2017 Cauldon reached a milestone of eight years of compliance with emission limits from the main stack.”
Cauldon in the community
“Cauldon produces nearly 1Mt of cement annually and directly employs over 150 people to achieve this. These are mostly in skilled non-seasonal positions. Another 30 people are indirectly employed in materials-handling, industrial cleaning, contract shale quarrying operations, scaffolding and security. The plant is responsible for about £11m (Euro13m) entering the regional economy each year, through salaries, business rates and through purchases from local suppliers. From day one, we were also conscious that introducing a very large new industry into a sparsely populated rural area brought its own challenges. That is why a sports and social club was opened near the plant in Waterfall Lane and a development of 24 homes was built. For many years a plant liaison group has helped to provide a formal process for meeting and for airing and solving any problems. A thriving veteran’s group also exists.”
Conclusions
“We have many technical and product achievements to our credit, but my thoughts are also with the people involved over the decades: Without them, the best equipment is of little value. We haven’t only made cement: We have helped to create a community. The villages around us, like Cauldon and Waterhouses, have grown and thrived partly because of the employment our business has been able to provide over 60 years. Now,” concluded Martin Bains, “after six decades and under the new ownership of Lafarge - now LafargeHolcim - we look forward to rising to our next challenges, with the dedication of our employees and with the active involvement of our communities.”
Plant profile: Lafarge Cauldon
Location: Cauldon, Staffordshire, UK
Kiln 1 (Lepol dry): 1957-1985*
Kiln 2 (Lepol dry): 1960-1985
Kiln 3 (Lepol dry): 1962-1983
Kiln 4 (Dry, FLSmidth kiln): 1985-present
Cement production capacity: 0.96Mt/yr
Other Lafarge UK plants:
Cookstown cement plant, Northern Ireland
5 import/export terminals (•)
*Kiln operation data from cementkilns.co.uk