Harefield

Location:

Clinker manufacture operational: 1880-7/1929

Approximate total clinker production: 790,000 tonnes

Raw materials:

Ownership:

Sometimes called Coles Shadbolt Works. The site was originally developed for brickworks. Coles Shadbolt made Roman Cement on the Regent’s Canal in Islington, and a dock on the Grand Union Canal was constructed at Harefield to ship bricks to Islington. In charge of this, Percy Shadbolt, who had previously worked at Waldringfield, recognised the suitability of the site for Portland cement. Francis says the plant was completed with twelve chamber kilns in 1880. However, the kilns were clearly installed piecemeal. The likely development was as follows: two bottle kilns (50 t/week) were installed in 1880. Three chamber kilns (80 t/week) were added in 1883 and two (55 t/week) in 1886, at which point the bottle kilns were removed. Four more chamber kilns (31 t/week each) were installed over the next four years, a tenth (29 t/week) in 1891 and two more (56 t/week) in 1893. A further two chamber kilns (56 t/week) were added in 1901, raising total output to 400 t/week, which was the output quoted by Davis for 1907. A rotary kiln was installed before the BPCM takeover; evidently two kilns were planned, but only one was ordered, and there was no chance of further expansion in view of the lack of raw material reserves and the suburbanization of the area. Five chamber kilns were removed to make way for the rotary kiln: the remaining nine (265 t/week) continued in place until the late 1920s, but were not used after 1914. The plant was described in a 1924 schedule. As with other plants, trials with slurry sprays were mandated in the late 1920s, and at the Blue Circle annual production conference, the plant manager gave a plaintive description of the resulting dust complaints from the well-heeled residents of the village. The plant’s closure corresponded with major new kilns coming on line at Swanscombe. The plant never had a rail link, and used the canal for heavy freight. After clinker manufacture ceased, lime was made, using the rotary kiln, until the early 1940s, after which the site was completely cleared. Nothing remains visible: even the canal spur has disappeared. The site and quarry remain waste ground.

Power Supply

The steam engine that originally directly drove the plant was replaced around 1900 with three gas engines and a diesel engine. For the rotary kiln in 1909, electric power for that section only was produced by a generator driven by another gas engine.

Rawmills

Two washmills (one washing chalk alone, the other washing clay with the chalk slurry), followed by vibrating screen separators.

One rotary kiln was installed:

Kiln A1

Supplier: FLS
Operated: 05/1909 -7/1929
Process: Wet
Location: hot end 504838,189872: cold end 504869,189842: entirely enclosed.
Dimensions: metric 43.00 × 2.400B / 2.100CD
Rotation (viewed from firing end): anticlockwise
Slope: 1/25 (2.292°)
Speed: ?
Drive: ?
Kiln profile: 0×1725: 700×1725: 700×2100: 2100×2100: 2100×2400: 9450×2400: 11475×2100: 43000×2100: Tyres at 1300, 12350, 25100, 36850
Cooler: “Double-back” concentric rotary metric 10.05 × 1.350 / 1.200 / 1.800 beneath the kiln.
Cooler profile: 0×1350: 3900×1350: 3900×1200: 9600×1200: 10050×1800: 4200×1800: tyre at 2400 with trunnion end bearing: turning gear at tail end.
Fuel: Coal
Coal Mill: indirect: FLS No.14 tube mill, 33kW
Exhaust: via drop-out box to stack.
Typical Output: 1909-1918 69 t/d: 1919-1929 80 t/d
Typical Heat Consumption: 1909-1918 9.18 MJ/kg: 1919-1929 9.02 MJ/kg



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