Northfleet Cement Works

APCM head offices were based at Stone Castle, which resided immediately north of Greenhithe’s Western Quarry. This was, fundamentally, a fortified house: most of the building dated from the 19th Century, although its distinctive castle-like tower is reputedly of 14th Century origin. APCM had occupied the building since 1907 as a managerial base for its local cement works; the company’s technical laboratories were also based in the grounds here. In this capacity the castle remained for nearly a century, but changes were afoot for the owning company. A change of identity emerged in 1978: APCM was renamed ‘’Blue Circle Industries Limited’’ (BCI). In the following year alone, worldwide sales for the company totalled £527.9 million, exports forming £69.4 million of this total. In addition to this, over 12,150 people were employed within the company, this of which had assets valued at £770.6 million. Despite these impressive figures, the export market was actually slowing down, and to cut costs and prevent excessive use of chalk, half the number of kilns at the Northfleet Works had been taken out of use by 1980, after a mere decade’s use. As costs continued to rise, new energy-efficient plans were put forward at Northfleet: two of the three remaining kilns were modified for ‘’semi-wet’’ operation, as opposed to their existing ‘’wet’’ processing. In brief, ‘’wet’’ operation involves feeding the kilns with raw materials in the form of a slurry, with excess water being removed by the application of heat. However, rising energy costs had made this an expensive process, and it was instead decided to remove the water not by heat, but rather filtration. This operation became known as ‘’semi-wet’’.

Economic recession set in during 1991, and as a consequence output fell to the extent that in 1993, Northfleet Works was working with just one kiln. In February of that year, the works ceased delivering cement from its Northfleet site by rail, and arrival of chalk and coal by this means only lasted until March. The 13th March 1993 marked the final day of rail operation to the site, and both the loop line and sidings went out of use. The company’s chalk works at Swanscombe had already been abandoned in 1991 due to deficient demand. Economic upturn saw the re-commissioning of a second kiln at Northfleet in 1994 in response to demand, but this was not enough to bring rail operation back to the site. Two kilns gave the site an annual output of 1.2 million tonnes of cement. It was also in 1994 that excavation ceased at Western Quarry, which by this time had grown to an area of 240 acres. In the pipeline was BCI’s own concept of transforming the redundant site into a modern shopping centre. The plans had received formal government approval, but on 25th June 1994, the exhausted quarry was instead sold to Australian real estate firm ‘’Lend Lease’’. It was this company which eventually undertook the Bluewater Shopping Centre project. BCI began winding down its operations in the area: in the year 2000, the company sold its offices at Stone Castle to property firm ‘’Land Securities’’, after 93 years tenure. The Stone Castle estate comprised an area of 46 hectares, which could be redeveloped into high-quality apartments and housing. Stone Castle was Grade II Listed and could become a standalone venture to lease to a third party once the surrounding land had been transformed for residential use. It was also during 2000 that plans for a new £180 million state-of-the-art cement works at Holborough, in the Medway Valley, were brought to the fore. This facility was destined to replace that at Northfleet. Then, in 2001, major change was heralded as BCI was purchased outright by the French-based ‘’Lafarge Group’’, a building materials firm which operated on a global scale. Consequently, the UK operation was swiftly re-branded ‘’Lafarge Cement’’ over the course of the year, but the ‘’Blue Circle’’ label was retained as a brand name, it carrying considerable goodwill.

In July 2001, construction work on Ebbsfleet International station began, and this involved utilising land once associated with the railway operation of Northfleet Works. Approximately half of the disused quarry, which accommodated the redundant cement works' loop line, was completely cleared of vegetation and the derelict track work severely cut back. Of the cement sidings beside Northfleet station, truncation occurred at the eastern end of the site, with the connection between the tracks and the loop being severed. By this time the sidings had no physical connection with the North Kent Line either. During 2001, plans had also come to light concerning the future of the 300 hectare Eastern Quarry, which Lafarge Cement had on lease until 2008. The huge expanse had become part of the ‘’Ebbsfleet Valley’’ project, and the former quarry was to house a completely new ‘’village’’ comprising houses, retail outlets, and schools. Planning permission demanded that at least one third of the total area available became open space, not subject to building work. Chalk operations at Eastern Quarry ended in 2007 and thereafter, a process of ‘’restoration’’ was begun, which has involved bringing in Thanet Sand to repair the pit’s surface area. Northfleet relinquished its association with cement production in 2008, when the works there, with its 300-strong workforce, closed. The iconic chimneys were brought crashing to the ground on 28th March 2010.

Cement Making at Northfleet
By Tom Burnham

Northfleet Works when built had 6 rotary kilns which were among the largest (in size) ever built. Total rated output was around 3.8 million tons a year (world's largest cement works when built) which would have needed some 600,000 to 700,000 tons a year of coal.

The chalk was moved from the quarry face to the washmills by conveyor belts. The washmills are basically large circular concrete tanks with a gantry with chains hanging from it rotating inside. Chalk and water go in, and the chalk is gradually ground down into a fine slurry. The flints help with the grinding, then fall to the bottom and are scooped out at intervals. The chalk slurry goes down to the works by pipeline, where it's mixed with clay slurry. Clay was dug at South Ockendon, Essex, made into a slurry and piped through a pipeline under the Thames (two were laid in, actually, in case one was ever blocked). The mixed chalk/clay slurry went into one end of the kilns, was gradually dried and heated up to about 1250°C by a pulverised coal flame at the other (slightly lower) end. The works was later altered with filter presses to remove some of the water in a more energy efficient way. The fired material (called clinker - rather like little grey pebbles) drops out of the hot end of the kiln, is cooled and then ground with about 5% of gypsum (to control the setting time) to make cement.

The gypsum was also delivered by rail of course, from Mountfield Sidings on the Hastings line. I believe the fleet of gypsum hopper wagons was APCM-owned (they certainly had Blue Circle logos) as were the bulk cement wagons (at first 100t GLW bogie vehicles, later partially superseded by 45t 4-wheel wagons - especially after some bogie wagons were lost in the Mottingham derailment). The MGR coal hopper wagons were BR owned.

Northfleet Cement Works

6th December 1983

6th December 1983