Cement Kilns

Kent

Location:

  • Grid reference: TQ57687525
  • x=557680
  • y=175250
  • 51°27'15"N; 0°16'10"E
  • Civil Parish: Stone, Kent

Clinker manufacture operational: 1922-1970

Approximate total clinker production: 16.4 million tonnes (27th)

Raw materials:

  • Upper Chalk (Seaford Chalk Formation: 85-88 Ma) from quarry at 557100,174500 initially worked by the Stone Court Chalk Land and Pier Co., and subsequently acquired by APCM: then 556900,173600
  • Alluvial Clay from Stone Marshes, then (1938) from Cliffe

Ownership:

  • 1919-3/1920 Kent Portland Cement Works Ltd
  • 3/1920-1922 Kent Portland Cement Co. Ltd
  • 1922-1970 APCM (Blue Circle)

The original company was launched to buy and install a large, modern, off-the-peg plant. Curiously, this FLS plant had Sydney Greenwood Robinson - also a director of Tunnel - as its Managing Director. It failed before the plant was complete, because of over-spend. It suffered a similar fate to other "promoter" ventures of the time. The original kilns were ordered from FLS in 1919 and the first kiln was already in place in early 1920. At this point the company was reconstituted with a doubling of capital. With false starts and equipment failures, the company ran out of cash and folded. APCM bought it from the liquidator. The kilns were allegedly turning during 1921, but at the time of Blue Circle’s takeover, no finished product had been made, and it can be assumed that any previous kiln runs did not constitute “production”. Subsequently, the FLS-designed plant became something of an APCM showpiece and influenced the development of subsequent Blue Circle/Vickers designs: in his books, Davis used many photographs of the plant as illustrations of “state-of-the-art”. Kilns A1 and A2 were the largest in Britain until 1926 when they were overtaken by Bevans A1-A3. The plant was operated by Blue Circle very much in concert with the adjacent Johnsons, with reserves strategically allocated between the two, and with the need for more capacity in the late 1930s, two more kilns were installed at Kent rather than Johnsons where the site was too cramped for expansion. Vickers Armstrong provided a new design for A3 and A4, presumably prompted by the craze for calcinator of the period: the calcinator experiment was quickly abandoned, and the precedent was applied with most of the calcinators that came under Blue Circle’s control.

The plant was provided with a rail link, but also despatched product by barge. After closure, the site was re-developed. A few fragments of the wharf remain: the plant site is covered by part of the Crossways industrial park.

Rawmills

Clay was washmilled separately (and from 1938 delivered as slurry by barge from Cliffe), and chalk brought from the quarry by rail was ground with the clay slip in washmill/screener combinations.

Four rotary kilns were installed:

Kiln A1

Supplier: FLS
Operated: 1/1922 -30/04/1970
Process: Wet: chain system installed 1931.
Location: Hot end 557695,175275: Cold end 557687,175202: entirely enclosed.
Dimensions:

  • 1922-?1931 Metric 75.00 × 3.450B / 3.000CD
  • ?1931-1962 245'0" × 11’0¼”B / 9'10⅛"CD (metric 74.68 × 3.359B / 3.000CD: burning zone replaced (Vickers Armstrong).
  • 1962-1970 239'0" × 11’0¼”B / 9'10⅛"CD (metric 72.85 × 3.359B / 3.000CD: shortened.

Rotation (viewed from firing end): clockwise.
Slope: 1/25 (2.292°)
Speed: ?
Drive: ?
Kiln profile:

  • 1922-?1931 0×3000: 3000×3000: 3000×3450: 15600×3450: 17400×3000: 75000×3000: Tyres at 1500, 18000, 32400, 49150, 66375.
  • ?1931-1962 0×2502: 2778×3359: 15259×3359: 17062×3000: 74676×3000: Tyres at 1486, 17983, 32322, 49136, 66358.
  • 1962-1970 0×2502: 2778×3359: 15259×3359: 17062×3000: 72847×3000: Tyres at 1486, 17983, 32322, 49136, 66358.

Cooler:

  • 1922-1949 concentric rotary metric 21.00 × 3.000 beneath the kiln
  • 1949-1970 rotary 90’6”× 9’0¾” (metric 27.58 × 2.762) beneath the kiln

Cooler profile:

  • 0×2100: 5500×2100: 5500×3000: 21000×3000: Tyres at 4572, 20422.
  • 0×2248: 1981×2762: 27584×2762: Tyres at 4572, 20422.

Fuel: Coal, except 4/1960-5/1968 on Oil
Exhaust: initially direct to stack. An ID fan was added in the early 1930s, and an electrostatic precipitator in 1962.
Typical Output: 1922-1931 313 t/d: 1931-1950 326 t/d: 1950-1960 344 t/d: 1960-1968 375 t/d: 1968-1970 314 t/d
Typical Heat Consumption: 1922-1931 9.51 MJ/kg: 1931-1950 7.85 MJ/kg: 1950-1960 7.69 MJ/kg: 1960-1968 7.90 MJ/kg: 1968-1970 8.50 MJ/kg

Kiln A2

Operated: 2/1922 -30/04/1970
Location: Hot end 557685,175276: Cold end 557677,175205: entirely enclosed.
Dimensions:

  • 1922-?1931 Metric 75.00 × 3.450B / 3.000CD
  • ?1931-1961 245'0" × 11’0¼”B / 9'10⅛"CD (metric 74.68 × 3.359B / 3.000CD: burning zone replaced (Vickers Armstrong).
  • 1961-1970 228'0" × 11’0¼”B / 9'10⅛"CD (metric 69.49 × 3.359B / 3.000CD: shortened.

Kiln profile:

  • 1922-?1931 0×3000: 3000×3000: 3000×3450: 15600×3450: 17400×3000: 75000×3000: Tyres at 1500, 18000, 32400, 49150, 66375.
  • ?1931-1961 0×2502: 2778×3359: 15545×3359: 16777×3000: 74676×3000: Tyres at 1486, 17983, 32322, 49136, 66358.
  • 1961-1970 0×2502: 2778×3359: 15545×3359: 16777×3000: 69494×3000: Tyres at 1486, 17983, 32322, 49136, 66358.

Exhaust: initially direct to stack. An ID fan was added in the early 1930s, and an electrostatic precipitator in 1961.
Typical Output: 1922-1931 313 t/d: 1931-1950 325 t/d: 1950-1960 348 t/d: 1960-1968 357 t/d: 1968-1970 296 t/d
Typical Heat Consumption: 1922-1931 9.50 MJ/kg: 1931-1950 7.65 MJ/kg: 1950-1960 7.70 MJ/kg: 1960-1968 7.86 MJ/kg: 1968-1970 8.41 MJ/kg
In all other respects identical to A1

Kiln A3

Supplier: Vickers Armstrong
Operated: 1938-30/04/1970
Process: Wet: originally fitted with calcinator. Since A4 had no calcinator, this was presumably an experiment to compare identical kilns with and without calcinators: it was removed 1946.
Location: Hot end 557705,175275: Cold end 557697,175204: entirely enclosed.
Dimensions (from cooler ports): 230’6⅛”× 10’10” (metric 70.26×3.302)
Rotation (viewed from firing end): clockwise?
Slope: ?
Speed: ?
Drive: ?
Kiln profile (from cooler ports): -597×2743: 1384×2743: 4432×3302: 70260×3302: Tyres at 6871, 23330, 44955, 66637.
Cooler: 12 × 14’6” × 3’11½” (metric 4.43×1.207) Reflex “Recuperator” planetary
Fuel: Coal, except 4/1960-5/1968 on Oil
Exhaust: via cyclones and an ID fan to stack.
Typical Output: 1938-1946 324 t/d: 1946-1960 348 t/d: 1960-1968 365 t/d: 1968-1970 322 t/d
Typical Heat Consumption: 1938-1946 7.84 MJ/kg: 1946-1960 7.87 MJ/kg: 1960-1968 7.95 MJ/kg: 1968-1970 8.49 MJ/kg

Kiln A4

Operated: 1939-30/04/1970
Process: Wet
Location: Hot end 557715,175273: Cold end 557707,175203: entirely enclosed.
Typical Output: 1939-1950 321 t/d: 1950-1968 360 t/d: 1968-1970 307 t/d
Typical Heat Consumption: 1939-1950 7.77 MJ/kg: 1950-1960 7.96 MJ/kg: 1960-1968 7.94 MJ/kg: 1968-1970 8.60 MJ/kg
Identical in all other respects to A3


Sources: Cook, p 65: Eve, p 13: Jackson, pp 233, 284: Pugh, pp 83, 91, 265-266


© Dylan Moore 2011: commenced 25/01/2011: last edit 31/12/16.

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Old Maps

Kent Detail

Approximate capacity: tonnes per year
Kent Capacity

Picture: ©English Heritage - NMR Aerofilms Collection. Britain from Above reference number EPW017653.
Britain from Above features some of the oldest and most valuable images of the Aerofilms Collection, a unique and important archive of aerial photographs. You can download images, share memories, and add information. By the end of the project in 2014, 95,000 images taken between 1919 and 1953 will be available online.
This was taken on 26/4/1927 and shows the plant from the northeast. View in High Definition.

Kent Picture
Picture: Blue Circle Archive. This shows Kilns 1 (left) and 2 (right) in 1928. For four years these were Britain's largest kilns. The concentric "double-back" coolers are still in place.

Kent 1939
This was taken on 27/2/1939 and shows the plant from the west. Kiln 4 installation was nearly complete. The building housing the calcinator on Kiln 3 is visible above the kiln house roof to the left of the stacks. The power house (at the shore end) is operating, and continued in use into the 1950s. With the doubling of the capacity of the plant in 1938-9, a second stack has been added to the power house. The washmill system (right) has been uprated. Near the wharf (just left of the stack plume) a slurry basin has been installed to receive clay slurry delivered by barge from Cliffe. In the right background is Johnsons wharf. Zoom in on this image in High Definition.