Cement Kilns

Holborough

Location:

  • Grid reference: TQ70536257
  • x=570530
  • y=162570
  • 51°20'12"N; 0°26'54"E
  • Civil Parish: Snodland, Kent

Clinker manufacture operational: 12/1924 to 10/1984

Approximate total clinker production: 16.2 million tonnes (28th)

Raw materials:

  • Middle Chalk (Holywell Nodular Chalk Formation: 92-94 Ma), Grey Chalk (Zig-zag Chalk Formation: 94-97 Ma) and Chalk Marl (West Melbury Marly Chalk Formation: 97-100 Ma) from quarry at 569300,162700
  • In later years, when high grade chalk was in excess, Gault Clay (Gault Formation: 100-112 Ma) from pit at 568900,161900

Ownership:

One of several “off-the-peg” independent plants built during the early 1920s, it was commissioned effectively but became vulnerable to takeover during the 1926/27 downturn. It forced a clean-out of the less-efficient plants in the upper Medway. Unlike the previous Medway plants, it was set up to make full use of its rail link, receiving coal by rail, although it also had a 700 ft wharf on the river, capable of loading ten barges simultaneously, and much use was made of this before the Blue Circle takeover. Because of its relatively good rail link and almost unlimited raw materials, it became Blue Circle’s most favoured Medway plant, and its last following the closure of Martin Earles in 1967. It was on the hit-list for closure with the start of Northfleet, but was reprieved following the latter’s failure to meet its design performance. In order to close capacity at Swanscombe, it was charged with making sulfate resisting cement: this was a disastrous failure, and precipitated the plant’s demise. Most of the plant was cleared, but significant parts, plus the quarry, were kept operable in order to maintain extraction permission for a possible replacement plant. The plant site, now called Vantage Point, is a road distribution depot, and all signs of the plant have been obliterated. The quarries remain untouched.

Rawmills

Initially there were two washmills (168 kW?), each with a screener in the quarry at 570260,162520. A further washmill with two screeners was added for the third kiln. Later, these were replaced by two washmills (260 kW?) and four screeners were installed further into the quarry at 569970,162630. There was no provision for grinding harder rawmix components.

Four rotary kilns were installed:

Kiln A1

Supplier: Vickers
Operated: 12/1924-10/1984
Process: Wet
Location: hot end 570530,162597: cold end 570511,162539: hot end enclosed.

Dimensions:
  • As installed: 200’0”× 9’10½”B / 8’10½”CD (metric 60.96 × 3.010 / 2.705)
  • From 1938: 198’5”× 9’10½”B / 8’10½”C / 12’6”D (metric 60.48 × 3.010 / 2.705 / 3.810)

Rotation (viewed from firing end): clockwise.
Slope: ?
Max speed: ?
Drive: 45 kW

Kiln profile:

  • 1924-1938: 0×2705: 3124×2705: 4191×3010: 15164×3010: 16231×2705: 60960×2705: tyres at 2134, 17221, 35509, 53797: turning gear at 33452
  • 1938-1984: 0×2705: 3124×2705: 4191×3010: 15164×3010: 16231×2705: 46050×2705: 48235×3810: 56871×3810: 60198×1829: 60477×1829: tyres at 2134, 17221, 35509, 53797: turning gear at 33452

Cooler: rotary: 86’0”× 6’6” (metric 26.21 × 1.981) beneath kiln
Cooler profile: 0×1981: 26213×1981: Tyres at 4343, 15316, 22479
Fuel: Coal, except 04/1961-08/1964 Oil, and 12/1968-01/1973 mixed fuels, typically 21% Oil / 79% Coal
Coal mill: originally indirect, with a set of Raymond Bowl Mills: later direct: Atritor.
Typical Output: 1924-1938 200 t/d: 1938-1959 269 t/d: 1959-1967 297 t/d: 1967-1980 282 t/d: 1981-1984 250 t/d
Typical Heat Consumption: 1924-1938 8.06 MJ/kg: 1938-1954 7.37 MJ/kg: 1954-1974 7.77 MJ/kg 1: 1974-1980 7.18 MJ/kg: 1981-1984 6.43 MJ/kg


Kiln A2

Operated: 02/1925-10/1984
Process: Wet
Location: hot end 570538,162594: cold end 570518,162537: hot end enclosed.
Dimensions: 200’0”× 9’10½”B / 8’10½”CD (metric 60.96 × 3.010 / 2.705)
Rotation (viewed from firing end): clockwise.
Kiln profile: 0×2705: 3124×2705: 4191×3010: 15164×3010: 16231×2705: 60960×2705: tyres at 2134, 17221, 35509, 53797: turning gear at 33452
Typical Output: 1925-1934 181 t/d: 1934-1943 242 t/d: 1943-1952 206 t/d: 1952-1962 229 t/d: 1962-1980 247 t/d: 1981-1984 222 t/d
Typical Heat Consumption: 1925-1934 8.62 MJ/kg: 1934-1948 7.73 MJ/kg: 1948-1967 7.29 MJ/kg: 1967-1975 7.59 MJ/kg: 1975-1980 7.05 MJ/kg: 1981-1984 6.46 MJ/kg
Identical in all other respects to A1


Kiln A3

Operated: 1926-10/1984
Process: Wet
Location: hot end 570547,162591: cold end 570528,162533: hot end enclosed.
Dimensions: 200’0”× 9’10½”B / 8’10½”CD (metric 60.96 × 3.010 / 2.705)
Typical Output: 1926-1934 182 t/d: 1934-1942 244 t/d: 1942-1952 215 t/d: 1952-1980 252 t/d: 1981-1984 219 t/d
Typical Heat Consumption: 1926-1934 8.51 MJ/kg: 1934-1948 7.63 MJ/kg: 1948-1960 7.30 MJ/kg: 1960-1975 7.60 MJ/kg: 1975-1980 7.05 MJ/kg: 1981-1984 6.45 MJ/kg
Identical in all other respects to A2


Kiln A4

Operated: 1938-1982
Location: hot end 570556,162588: cold end 570537,162530: hot end enclosed.
Dimensions: 200’0”× 9’10½”B / 8’10½”C / 12’10½”D (metric 60.96 × 3.010 / 2.705 / 3.924)
Rotation (viewed from firing end): clockwise
Kiln profile: 0×2134: 1372×2667: 3124×2667: 4191×3010: 15164×3010: 16231×2705: 48895×2705: 51079×3924: 57353×3924: 60681×1829: 60960×1829: tyres at 2134, 17221, 35509, 47498, 59436: turning gear at 33452
Cooler: rotary: 86’9”× 6’6” (metric 26.44 × 1.981) beneath kiln
Cooler profile: 0×1981: 26441×1981: Tyres at 7518, 21234
Typical Output: 1938-1946 251 t/d: 1946-1955 267 t/d: 1955-1972 255 t/d: 1972-1980 288 t/d: 1981-1982 219 t/d
Typical Heat Consumption: 1938-1961 7.66 MJ/kg: 1961-1964 8.03 MJ/kg: 1964-1968 7.56 MJ/kg: 1968-1974 8.25 MJ/kg: 1974-1980 7.26 MJ/kg: 1981-1982 6.70 MJ/kg
Identical in all other respects to A1



Sources: Cook, pp 72, 75: Eve, p 31: Jackson, pp 228, 281: Preston, p 202: Pugh, pp 96, 109, 264: “A Modern Cement Factory”, Cement and Cement Manufacture, 2, 1929, pp 7-13. A training film made at Holborough in the 1940s can be viewed at British Pathé.


© Dylan Moore 2011: commenced 07/08/2011: last edit 31/12/16.

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Old Maps

A detail plan of the plant has been commenced, but further progress is prevented by lack of information on the layout of the plant.

Approximate capacity: tonnes per year
Holborough Capacity

Picture: ©English Heritage - NMR Aerofilms Collection. Britain from Above reference number EPW019907.
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 October 1927 as part of a series commissioned by Red Triangle during purchase of this and other plants and shows it from the west. The washmills were in the quarry to the west, and slurry was pumped to the mixers in the top-left, then under the road to the kiln feed mixers. View in High Definition.

Picture: ©English Heritage - NMR Aerofilms Collection. Britain from Above reference number EPW020919.
This was taken in April 1928 and shows the plant from the east. The washmills and quarry can be seen. The raw material was mainly lower chalk at this stage. As the quarry extended into the hill, more middle chalk was obtained, requiring addition of Gault Clay from further south. Zoom in on the view in High Definition.