Cement Kilns

Stockton

Stockton LogoNelson's Cock Brand.

Location:

  • Grid reference: SP44196480
  • x=444190
  • y=264800
  • 52°16'46"N; 1°21'8"W
  • Civil Parish: Leamington Hastings, Warwickshire: the lias quarry and the raw material preparation plant were in Stockton parish

Clinker manufacture operational: 1872-5/1945

Approximate total clinker production: 1.83 million tonnes

Raw materials: Blue Lias Limestone and Clay (Rugby Limestone Member: 195-200 Ma) from quarry at 444250,264250, upgraded by rumbling. The Lias was 60% clay of around 35% CaCO3, and 40% limestone of around 78% CaCO3, and most of the clay was sidecast. The Lias was of too low a grade for modern cement, and from 1919, supplementary high-grade sweetener limestone (4-11% of dry rawmix) was bought:

  • initially Great Oolite limestone (Blisworth Limestone Formation: 165-168 Ma) from Roade, Northamptonshire (475900,251520) (39 km by rail)
  • after 1934 also Inferior Oolite limestone (Lower Lincolnshire Limestone member: 168-172 Ma) from Corby, Northamptonshire (492010,289090)

Ownership:

Sometimes called Nelson’s Works. The site made lime from early times and like Southam had its own dock on the Grand Union Canal. The manufacture of “cement” dates from 1857, but as with the other Warwickshire plants, true Portland cement was not made until later: around 1872 in this case, when two small dry process bottle kilns were employed. The number of small bottle kilns was gradually increased, and a set of chamber kilns may have been added, perhaps around 1889.

A historical account of this plant is hampered by lack of data, and particularly by lack of maps. As with many rural areas, there is no map edition between the 2nd edition County Series of 1909 and the late 1960s revision. This means that no map shows the rotary kilns, and the only evidence for their location are a few poor quality aerial photographs of the 1930s. The fact (if it is a fact) that there were chamber kilns originates from a statement in a valuation document drawn up by a law firm in 1910 (Rugby Archive RS/9/1/5/6) which says “there are several old slurry drying Kilns, no longer required as such, which we understand will be converted into, and used as Clinker Stores.” The 1909 map does not depict anything that can be unambiguously identified as a chamber kiln block. The 1930s aerial photography shows an area where clinker is being stacked, with little indication that it might once have accommodated chamber kilns, but if it did, then a rectangle 98’ × 80’ can be identified, and, as it happens, there is a tall brick stack at one corner. This, depending on orientation, could contain six 22 tonne or four 30 tonne kilns. This information could be regarded as tenuous enough to ignore, were it not for the fact that the maps show the bottle kilns to be very small – the twenty-three amounting to only 302 t/week capacity. With the three Schneider kilns making 240 t/week, some 160 t/week extra capacity is needed to make the 700 quoted by Davis. (Davis is generally very reliable, using his own objective expert assessments of the plants rather than “declared” capacities.) I therefore go for the 6×22 tonne arrangement. Further circumstantial justification is the fact that wet process rotary kilns were chosen. All the Warwickshire manufacturers were watching each other closely at this time, and collaborating to a significant extent. Both Rugby and Harbury had chamber kilns and chose the wet process. Southam had dry process bottle kilns and chose the dry process. Previous experience of making slurry was evidently decisive, and without chamber kilns, Stockton would have had no need to make slurry.

Around 1902, three of the later bottle kilns were converted into Schneider kilns. By 1907 there were 8 lime kilns and 23 cement bottle kilns (305 t/week), six chamber kilns (135 t/week) and three Schneider kilns (240 t/week), totalling 680 t/week, corresponding to Davis’ estimate of 700 t/week. The Schneider kilns were converted to forced-draught (together 450 t/week) in 1908. These used dry-ground briquetted rawmix. The use of static kilns ceased in 1913. New continuous lime kilns were installed at the same time as the rotary kilns, and the plant continued to make a significant amount of Lias lime.

The plant did not expand up to the depression, and Rugby took a share in the near-bankrupt company in 1937. Following complete takeover in 1945, it became clear that there was no point in keeping it as a separate unit alongside the newly modernised Southam, and production ceased immediately, with the plant continuing to function as a depot until it closed in 1949. In addition to the canal, the plant also had a railway connection through the L&NWR Weedon-Leamington branch from 1895. The plant site remained derelict for many years, and was finally cleared of structures in 1968. The canal spur was filled in and the site has remained waste land, with foundations still visible. The quarries are partially back-filled, but mainly flooded.

Although this was the most important Warwickshire plant at the start of the twentieth century, information is hard to come by, and this account is far from satisfactory. Please contact me with any relevant information or corrections. I am particularly interested in firmer dates and statistics, pictures and plans.

Rawmills

Originally Collis and flat stone mills were used, grinding stone brought from the quarry by tramway. By 1905, they had 3 tube mills (size unknown) for wet grinding. In 1919, a wet "combination" tube mill was installed at the quarry, and the Lias was pumped to the plant as a slurry. At the plant, a second combination mill ground the slurry with added bought-in sweetener limestone.

Two rotary kilns were installed:

Kiln A1

Supplier: Edgar Allen
Operated: 6/1910-5/1945
Process: Wet
Location: hot end 444199,264766: cold end 444187,264725: totally enclosed
Dimensions: 140’0” × 8’0”B / 7’0”CD (metric 42.67 × 2.438 / 2.134)
Rotation (viewed from firing end): anticlockwise
Slope: ?
Speed: ?
Drive: ?
Kiln profile: 0×2134: 2134×2134: 3658×2438: 7010×2438: 10668×2134: 42672×2134: tyres at 1524, 12192, 25298, 38100: turning gear at 26518.
Cooler: rotary 61’4”× 4’6” (metric 18.69 × 1.372) beneath kiln
Cooler profile: 0×1372: 18694×1372: Tyres at 2997, 15646
Fuel: Coal
Coal mill: indirect: common rotary drier followed by combination tube mill
Typical Output: 1910-1921 54 t/d: 1922-1933 60 t/d: 1934-1945 75 t/d
Typical Heat Consumption: 1910-1933 9.48 MJ/kg: 1934-1945 9.03 MJ/kg


Kiln A2

Operated: 1913-5/1945
Location: hot end 444204,264765: cold end 444192,264724: totally enclosed
Rotation (viewed from firing end): clockwise
Identical in all other respects to A1



Sources: Cook, p 115: Francis, pp 215-216: Jackson, pp 288, 299



Old Maps

Preparation of a detail plan remains impossible due to an almost complete lack of layout information and site plans.

Approximate capacity: tonnes per year
Stockton Capacity

Stockton 1937
Picture: ©English Heritage - NMR Aerofilms Collection. Catalogue number R2841. A high-definition version can be obtained from English Heritage. This was taken in 1937, looking southeastward. At the bottom left is the canal, with the plant spur branching off. At the top right is the main lias quarry, with large piles of clay spoil. The building with a sloping awning, was probably the Schneider kilns. In front of the tall stacks is a building - presumably a clinker store - connected by conveyor to the kiln house. The power plant (front left) was operating. The finish mills were presumably behind this, and three cement silos are beyond these. The ruinous buildings at the left rear of the plant seem to have contained earlier rawmills.

The Warwickshire County Record Office holds sales ledgers from Charles Nelson & Co's plant at Stockton (temporary catalogue numbers RS 9/5/1-5). I present the data here because it represents an exceptionally long (over 50 years) time series of uniformly-gathered data, and because it refers to the idiosyncratic history of the Warwickshire industry. In Warwickshire, the Blue Lias district produced "engineering-grade" hydraulic limes from the 18th century, and these became popular throughout Britain when the building of canals allowed them to be distributed nationwide. When Portland cement began to be produced from the 1840s onwards, Blue Lias Lime was one of the established products with which it had to compete, and the reliability of this lime ensured that it remained in favour for certain applications well into the 20th century. Its production continued at the Warwickshire plants until WWII.

The Stockton plant was established on a site previously worked for lime in 1844. Portland cement made with a ground rawmix commenced production in 1872, and by 1886 its capacity was 15000 t/year of Portland cement and 25500 t/year of lime - about 63% lime. The lime was marketed in three forms: lump lime, ground lime and Selenitic lime. The vast majority (80-90%) was sold as ground lime, which is the familiar Blue Lias hydraulic lime, made by grinding the lump product without any slaking. Lump lime was probably made from stone from known high-carbonate floors. Selenitic lime was made by adding 5% gypsum at the grinding stage as a retarder, and was used in mortars. By the start of the following records in 1897, the relative position of lime and cement had reversed, with lime down to around 40% of tonnage.

YearOwn Product Sold tonnesPurchased Materials Resold tonnesTotal Sales tonnes
Lump LimeGround LimeSelenitic LimeOPCRHPCLump LimeGround LimePlasterCementLump LimeGround LimeSelenitic LimePlasterCement
189747414042800155740 206644843477304 25401852680034722878
1898953148071062209520 252648185124476 347919625106251225428
1899911137121118205070 197840985005120 288917810111850025627
1900465119531471204800 189357055578152 235817658147155728632
1901802130051182209550 110349556826883 190517960118268227838
1902878121381588205330 79428635636455 167215001158856326988
19031706142411034227170 68428574367686 239017098103443630403
19041711155821106223970 35724573686755 206818039110636829152
190531989661943238800 2719503954712 34691061194339528592
1906231411566832277410 43612754194668 27501284183241932409
190728199711931237030 701664224103 2889987793142227806
190825657629710200150 904623713207 2655809171037123222
190919198461792166640 14002302430 2059846179223019094
191031139507651251570 21006112419 3323950765161127576
191120407353546321710 3221276973040 2362748054669735211
191211587108440410420 1571012312545 1315720944023143587
19137745546634404770 5802184433 832554663421844910
191415804207169396790 8101425320 1661420716914244999
19155832636145315300 12121125251 704263814511236781
1916391416115293350 540981988 9314161159831323
19176391357251980 1019911885 73932579127083
191867100581237760 15893957 821013819324733
19191479846235820 3562062059 498044620625641
19207164557267030 5302603089 6016455726029792
19213601610273231940 8811241891 448162127324124085
19223342161141336460 5611491142 390216214114934788
1923314667588367720 34151122026 34866908811238798
1924246344648306470 3901521760 28534464815232407
1925429356397367850 48151481250 47735789714838035
1926283261067328940 139112031080 42226216720333974
1927257269831355880 6160214272 87326983121435860
1928238252828376340 025256423 23825532825638057
1929185253739319540 640305475 24925373930532429
1930181381974335940 7610445267 25738297444533861
1931442292089323530 2212669284 46429328966932637
1932202231672333120 340708176 23623167270833488
1933226344078349570 2112492234 24734527849235191
1934336287884354740 71079119 4072878847935593
19353443005131377270 681680219 412300613168037946
19367973720125477290 125440818440 922416012581848169
19378603803189506451158 90326465289 950412918946552092
1938216369380489621739 3068171171 24637618017150872
1939343212114561661962 974483495 43328611448358623
194083256619464082455 588406670 8826541940649533
194110144010414802150 109649447 2015361049443677
1942012510353792624 91534141830 91404041439833
194307160316031920 026835445 0984035433568
194407770298051559 003090 0777030931364
194504970235091460 02212518252 0718025133221
1946019301371130 053831335290 0731031336791
194700000 072329837025 0723029837025
194800000 057221327817 0572021327817
194900000 0160626967 01600626967

It is noticeable that, particularly in the earlier period, a large proportion of the lime and cement sold was not made by Nelsons. The majority of these materials were sold at remote sales points, particularly London, and were packed under the Cock logo by other producers - mainly the other Warwickshire producers.

stockton sales
stockton lime

The total tonnage produced on site varied remarkably little during the period, and never rose very much above the 40,000 tonnes capacity in 1886. However, the amount of lime in the mix consistently fell. It is noticeable that lime production was set aside during both World Wars. Other Blue Lias Lime producers ceased manufacture earlier: Rugby in 1932, Barrow and Southam in 1935, Barnstone in 1938, Aberthaw and Harbury in 1939.

Note 1.

- o - O - o -

NOTES

Note 1.

Original content © Dylan Moore 2011: commenced 07/08/2011: last edit 15/06/2017.

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