Cement Kilns

Johnsons

Johnsons LogoI. C. Johnson's Elephant brand.

Location:

  • Grid reference: TQ57927477
  • x=557920
  • y=174770
  • 51°27'0"N; 0°16'22"E
  • Civil Parish: Stone, Kent

Clinker manufacture operational: 1877-1971

Approximate total clinker production: 22 million tonnes (19th)

Raw materials:

  • Upper Chalk (Seaford Chalk Formation: 85-88 Ma) by rail from nearby quarries:
    • 557800,174900
    • 558500,174300
    • 558100,173600
  • Various clays:
    • 1877-1920 Alluvial Clay from the Medway estuary
    • 1920-1964 London Clay (London Clay Formation: 48-55 Ma) from Bean 558700,171800
    • 1964-1971 Alluvial clay from Cliffe 571400,177100

Ownership:

On the 1872 map, there was a quarry on the site, with a tramway leading to what became “Johnson’s Wharf”, for supplying chalk ballast. It was claimed by Johnson to be one of the oldest chalk ballast quarries on the Thames, and it had previously supplied I. C. Johnson’s plant at Gateshead. Johnson bought the freehold around 1875, and had a plant with 15 Johnson kilns in operation by 1877 (rated output 350 t/week). The number of chamber kilns rose to 54 before rotary kilns were installed. The rough sequence of expansion was as follows:

  • Kilns 1-15: 1877-1911: 350 t/week
  • Kilns 16-22: 1881-1916: 200 t/week
  • Kilns 23-30: 1888-1924: 185 t/week
  • Kilns 31-33: 1890-1911: 90 t/week
  • Kilns 34-41: 1896-1924: 190 t/week
  • Kilns 42-45: 1898-1924: 90 t/week
  • Kilns 46-54: 1901-1924: 215 t/week

All these had (according to Johnson) heat consumption ~10.6 MJ/kg. This oft-quoted figure is undoubtedly an under-estimate, referring only to “flat-out” production. Since capacity utilization was typically 60-70%, normal heat consumption was probably much nearer the 14 MJ/kg typical of chamber kilns.

The company was part of the APCM amalgamation in 1900, but dropped out, as did West Kent and Weekes. The departure of Johnson’s caused particularly bad feeling, since the company was a major player, and its directors had been much involved in the project. The company tried hard to repair relations with APCM, and after the BPCM takeover, it played a major part in the new company. Because of its significant chalk land holdings, the plant remained an important part of Blue Circle’s Thames-side operation. Kilns A4-A7 demonstrated a commitment to aggressive expansion, and A6 and A7 were Britain’s largest kilns until overtaken by West Thurrock A6 in 1934, providing Vickers Armstrong with a successful design that was subsequently installed at many other locations. The addition of kilns 6 and 7 also made the plant Britain's largest from 1930 (overtaking Bevans) to 1933 (after which it was overtaken by West Thurrock). The plant became too cramped for further expansion after this. Johnson’s 91 m brick stack, constructed originally for the chamber kilns in 1877, remained in use until closure. The plant made sulfate resisting clinker alongside ordinary clinker from the late 1940s to 1971. The plant was the first on Thames-side (1933) to fit electrostatic precipitators.

Initially relying solely on its wharf for shipping, a rail link was established from the 1900s, but water transport remained important for despatch of product. After closure, the site was re-developed. Johnson’s Wharf, originally used for chalk export, is still in use, ironically for intake of aggregates for a Lafarge ready-mix plant. The plant site is largely under a housing estate. The original quarry is now a small park, and the site of the old stack, once the tallest in southern England, is preserved on a small mound. The main chalk quarry became the Western Quarry for Northfleet, and is now occupied by the Bluewater Retail Park.

The initial plant is described in an article in Building News. The progressive development of the plant is described in a further three articles.

Rawmills

Washmills were used, located at various places around the plant site, fed with chalk brought by rail from the quarry and clay by rail from the wharf. While the Bean clayfield was in operation, clay was washmilled there, and pumped to the plant. The chamber kiln plant had two washmills (? 15’ - ?30 kW each) in series with a set of six flat stones (20-25 kW each). In the final (late 1920s) plant there were two 30’ (168 kW) washmills. Larger grit was removed from the washmill product by eight vibrating screens, then the fine slurry was distributed between four 261 kW tube mills. The screen oversize was passed to two 22 kW screening mills, with the fine product returning to the main washmills. Material rejected by the washmills and screening mills entered an elaborate flint handling system.

Seven rotary kilns were installed:

Kiln A1

Supplier: FLS
Operated: 4/1907-1921
Process: Wet
Location: hot end 558059,174799: cold end 55093,174798: entirely enclosed.
Dimensions: metric 34.00 × 2.100
Rotation (viewed from firing end): clockwise.
Slope: 1/25 (2.292°)
Speed: 1.0-2.0 rpm
Drive: about 35 kW: a single 142 kW motor droves all three kilns and coolers
Kiln profile: 0×2100: 34000×2100: Tyres at 1475, 12010, 25970: Turning gear at 12905.
Cooler: “Double-back” concentric rotary metric 9.50 × 1.050 / 1.650 beneath the kiln.
Cooler profile: 0×1200: 3640×1200: 3640×1050: 3920×1050: 3920×1650: 9500×1650: Tyre at 2150 with trunnion end bearing: Turning gear at tail end.
Fuel: Coal
Coal Mill: Indirect: ball mill
Exhaust: via dry drop-out chambers direct to stack.
Typical Output: 57 t/d
Typical Heat Consumption: 9.05 MJ/kg


Kiln A2

Operated: 4/1907-1921
Location: hot end 558059,174793: cold end 55093,174792: entirely enclosed.
Identical in all respects to A1

Kiln A3

Operated: 4/1907-1921
Location: hot end 558059,174787: cold end 55093,174786: entirely enclosed.
Identical in all respects to A1

Kiln A4

Supplier: Ernest Newell
Operated: 1913-1966
Process: Wet
Location: hot end 557936,174817: cold end 557875,174829: hot end enclosed.
Dimensions: 202’0” × 10’0”B / 8’6”CD (metric 61.57×3.048/2.591)
Rotation (viewed from firing end): clockwise
Slope: 1/25 (2.292°)
Speed: ?
Drive: 48 kW
Kiln profile: 0×2292: 3048×3048: 15227×3048: 16675×2591: 61570×2591: Tyres at 1759, 17412, 31064, 43409, 57150.
Cooler:

  • 1913-1921 rotary 68’0”× 7’0”/ 5’6” (metric 20.73×2.134/1.676) beneath the kiln
  • 1921-1966 rotary 119’5”× 6’3” / 5’6” / 7’0” (metric 36.40×1.905/1.676/2.134): the same cooler, reversed, with a piece of kiln added to the cold end, and turned through 90º

Cooler profile:

  • 1913-1921 0×2134: 9144×2134: 10363×1676: 20726×1676: Tyres at 5080, 16662
  • 1921-1966 0×1829: 864×2134: 2515×2134: 3658×1905: 5639×1905: 7747×1676: 26035×1676: 27254×2134: 36398×2134: Tyres at 4623,19736,31318.

Fuel: Coal 1913-1960: Oil 1960-1966
Coal Mill: believed to have been direct: British Rema ring-roll mill.
Exhaust: initially direct to stack. From 1933, via ID fan and electrostatic precipitator.
Typical Output: 1913-1930 169 t/d: 1930-1960 214 t/d: 1960-1966 219 t/d
Typical Heat Consumption: 1913-1930 8.61 MJ/kg: 1930-1960 7.43 MJ/kg: 1960-1966 7.48 MJ/kg


Kiln A5

Supplier: Vickers
Operated: 1921-1966
Process: Wet
Location: hot end 557934,174810: cold end 557874,174822: hot end enclosed.
Dimensions: 202’0” × 9’10½”B / 8’10½”CD (metric 61.57×3.010/2.705)
Rotation (viewed from firing end): clockwise
Slope: ?
Speed: ?
Drive: 48 kW
Kiln profile: 0×2375: 2972×3010: 15164×3010: 16231×2705: 61570×2705: Tyres at 1372, 17221, 35509, 53797.
Cooler: rotary 82’6”× 8’5”/ 6’4” (metric 25.15×2.565/1.930) at right angles to kiln

Cooler profile: 0×2083: 1067×2565: 5029×2565: 6401×1930: 25146×1930: Tyres at 3810, 18796.
Fuel: Coal 1921-1960: Oil 1960-1966
Coal Mill: believed to have been direct: British Rema ring-roll mill.
Exhaust: initially direct to stack. From 1933, via ID fan and electrostatic precipitator.
Typical Output: 1921-1930 212 t/d: 1930-1960 235 t/d: 1960-1966 225 t/d
Typical Heat Consumption: 1921-1930 9.00 MJ/kg: 1930-1960 7.65 MJ/kg: 1960-1966 7.52 MJ/kg


Kiln A6

Supplier: Vickers Armstrong
Operated: 1928-27/03/1971
Process: Wet
Location: hot end 557914,174777: cold end 557823,174796: entirely enclosed.
Dimensions:

  • 1928-?1950 (from cooler ports) 300’0” × 11’10”/ 13’9¾”/ 10’1¼”/ 13’1” (metric 91.44×3.607/4.210/3.080/3.988)
  • ?1950-1960 length (from cooler ports) 314’7” (95.86 m)
  • 1960-1971 length 304’3½” (92.75 m)

Rotation (viewed from firing end): clockwise.
Slope: ?
Speed: 0.29-0.86 rpm
Drive: 119 kW
Kiln profile:

  • 1928-?1950 (from cooler ports): -584×3200: 3137×3200: 4877×3607: 17805×3607: 19685×4210: 31877×4210: 33807×3080: 78715×3080: 80645×3988: 91440×3988: Tyres at 6884, 23952, 37211, 54204, 71501, 87960.
  • ?1950-1960 (from cooler ports): -584×3200: 3137×3200: 4877×3607: 17805×3607: 19685×4210: 31877×4210: 33807×3080: 78715×3080: 80645×3988: 95885×3988: Tyres at 6884, 23952, 37211, 54204, 71501, 87960 (back end extended).
  • 1960-1971: 0×3200: 1740×3607: 14669×3607: 16548×4210: 28740×4210: 30671×3080: 75578×3080: 77508×3988: 92748×3988: Tyres at 3747, 20815, 34074, 51067, 68364, 84823 (planetary coolers removed).

Cooler:

  • 1928-1960 Reflex “Recuperator” planetary 12 × 18’2”× 3’11½” (metric 5.54×1.207)
  • 1960-1971 Fuller 750H grate

Fuel: Coal 1928-1960, 1968-1971: Oil 1960-1968
Coal Mill: Indirect: closed circuit ball mill
Exhaust: initially direct to stack. From 1933, via ID fan and electrostatic precipitator.
Typical Output: 1928-1930 436 t/d: 1930-1950 485 t/d: 1950-1960 509 t/d: 1960-1968 481 t/d: 1968-1971 400 t/d
Typical Heat Consumption: 1928-1930 8.82 MJ/kg: 1930-1950 7.54 MJ/kg: 1950-1960 7.12 MJ/kg: 1960-1968 7.54 MJ/kg: 1968-1971 7.39 MJ/kg


Kiln A7

Supplier: Vickers Armstrong
Operated: 1928-27/03/1971
Process: Wet
Location: hot end 557912,174765: cold end 557821,174784: entirely enclosed.
Dimensions:

  • 1928-?1950 (from cooler ports) 300’0” × 11’10”/ 13’9¾”/ 10’1¼”/ 13’1” (metric 91.44×3.607/4.210/3.080/3.988)
  • ?1950-1958 length (from cooler ports) 314’7” (95.86 m)
  • 1959-1971 length 304’3½” (92.75 m)

Kiln profile: as A6, with modifications at slightly different dates.
Cooler:

  • 1928-1958 Reflex “Recuperator” planetary 12 × 18’2”× 3’11½” (metric 5.54×1.207)
  • 1959-1971 Fuller 750H grate

Typical Output: 1928-1930 433 t/d: 1930-1950 493 t/d: 1950-1960 497 t/d: 1960-1968 494 t/d: 1968-1971 449 t/d
Typical Heat Consumption: 1928-1930 8.93 MJ/kg: 1930-1950 7.79 MJ/kg: 1950-1960 7.16 MJ/kg: 1960-1968 7.63 MJ/kg: 1968-1971 7.47 MJ/kg
Identical in all other respects to A6.



Sources: Eve, p 13: Francis, p 154: Jackson, pp 232, 283: Pugh, pp 264-265: Building News and Engineering Journal, 2/7/1880 pp 5-7: The Engineer, XCIII, February 7, 1902, pp 130-133: ibid, CV, February 28, 1908, pp 211-213, 220: “Johnson’s Cement Works, Greenhithe”, Cement and Cement Manufacture, 2, 1929, pp 97-107, 161-170.

Read the Building News article and the three later articles.


© Dylan Moore 2011: commenced 12/03/2011: last edit 18/12/2016.

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Old Maps

Johnsons DetailThis is a composite map containing details from different eras that may not have co-existed.

Approximate capacity: tonnes per year
Johnsons Capacity

Johnsons 1-3Kilns 1-3 viewed from the top of the back-end chamber, around the time of commissioning in 1907. A typical "second-generation" kiln installation. The concentric coolers can be seen below the kilns.

Johnsons 1924 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 in September 1924 and shows the plant from the east in a period when the first five are present. Kilns 4 & 5 are in the open, with a long duct connecting them to the tall 1874 stack. Kilns 1-3 are still in place (near the bottom edge) although apparently not running. The rawmills and finish mills are still in their original location. The old chamber kilns are still relatively intact, although long disused. In the right background is the disused Artillery plant with a tall stack. Zoom in on the plant in High Definition.

Johnsons 1939 This was taken on 27/2/1939 and shows the plant from the southeast. Kilns 6 & 7 are running. Kilns 4 & 5 are in the open, to the right of the kiln house. To the left of the kiln house the remains of the main chamber kiln bank can still be seen. In front of the main stack are the electrostatic precipitators that had been retro-fitted on the kilns in 1933. The new washmill plant is in the foreground. To the right of the washmill sidings are tanks holding clay slurry. By 1939, clay slurry was being delivered by barge from Cliffe. The centre is occupied by the new finish mills and cement silos built over the site of kilns 1-3. In the right foreground is the bank of shaft limekilns that continued in use into the 1960s. In the right background is the Kent plant. Zoom in on the plant in High Definition.