Billingham

Casebourne Billingham Pioneer Brand cement logo
Casebourne's Pioneer Brand.
ICI cement logo
ICI sold cement under its own brand from 1928, continuing at Tunstead after Billingham closed.

Location:

Clinker manufacture operational: 1904 - 1970

Approximate clinker production to 2015:

Overall 12.4 million tonnes (34th).

Raw materials:

Ownership:

This was alternatively called Casebourne’s Works, Haverton Hill Works or Pioneer Works. It was the longest-lasting and most diverse in the category of waste-consuming cement plants, and by far the largest in terms of total output. It could arguably be treated as two plants, since the conventional and sulphuric acid plants were rather far apart, but their operation was always closely coordinated. It was initially constructed to replace the cramped Cliff House site in West Hartlepool, with good wharfage on the River Tees on previously undeveloped land east of the Tees Salt Works which was the first industry in the area. It would use chalk ballast from the area, supplemented and subsequently replaced by chalk shipped directly from the Thames. The installation of four rotary kilns was the largest of the time outside the APCM orbit, Davis' 1907 capacity of 1200 t/week indicating that the kilns were each producing around 45 t/day. The plant claimed that they were the first rotary kilns in Britain. Something like fifty kilns had in fact preceded them (see article). However, it appears to have been the first-started green-field plant to be designed exclusively with rotary kilns — the contemporaneous Fellner & Ziegler plant at Norman started most probably in September 1904, about a month later.

During the disruption of shipping in WWI, Thames chalk was replaced by Chiltern chalk brought in by rail before being replaced (in 1919) by chalk from Wharram. Clinker was also being purchased from Earle’s during 1917. Despite these difficulties the plant (uniquely among the northern plants) ran through the war. The alternative raw material source was probably the reason for the plant’s longevity compared with others in this group: among the north-east coast plants, only this, Warren and Wilmington had the confidence to replace Thames chalk with a local material, and the others were rapidly killed off by WWI and the subsequent two decades. Nevertheless, because of transport costs and royalties, Wharram chalk was still expensive, costing in 1926 £0.15 per tonne at a time when cement was selling for £2.00. Warren, still on Thames chalk, were paying £0.275.

A government project was set up in 1917 to construct a Haber process ammonia plant to the northwest of the plant to make synthetic fertilizer independent of imports. Synthetic Ammonia and Nitrates Ltd (SA&N: a purpose-formed subsidiary of Brunner-Mond) bought the still-empty site plus rights to the process in 1920, and a plant finally got under way in January 1924. Trials for use of “sulfate plant mud” as a replacement for chalk at the cement plant took place in December 1924-January 1925, and from then on, the Wharram chalk was partially or totally replaced with this waste calcium carbonate, which was otherwise dumped at sea. The mud contained unreacted anhydrite and ammonia, and the clinker was always high in sulfate. In 1926, a new cement company was launched (with SA&N money) to finance a major upgrade, and following the successful commissioning of kiln B1 using waste carbonate, ICI, the successors of SA&N, bought the company out in 1928.

In 1929, ICI converted the kilns to a nominal “semi-wet” process by use of vacuum filters, which reduced feed moisture content from a typical 41.5% to a thick paste of around 30% H2O – a 40% reduction. This also removed about 40% of the soluble salts. Vacuum filtration, because of its low pressure drop, can’t produce a highly-consolidated filter cake. It was the first British plant to employ the semi-wet process. Nonetheless, high fuel consumptions around 8.6 MJ/kg were the norm.

In 1931, the UK’s first Anhydrite Process kiln was started on a site some distance away. From this time on, both conventional and anhydrite process clinker was produced, the finished cement being made at the conventional plant from a blend of the two. The anhydrite process clinker was transferred to the main plant by aerial ropeway (0.33 km). The first kiln was lit 10 February 1930, but did not make clinker for some time and only made a usable product from May 1931. The anhydrite kilns had a lower production rate than anticipated, and it was a long time before even moderate run times on good product were achieved. The plant ran through WWII, except that B1 was out of action 26/7/1942 to April 1943 due to a direct bomb hit on the burning zone and the coal mill. Following the sulfur-shortage scare of the early 1950s, a third, larger anhydrite kiln was installed in 1954, while ICI also collaborated in the building of Widnes. Data on the operation of the early plant is given in an article below.

From the takeover by ICI, the plant became tightly integrated into the Billingham chemical complex, as part of a complex web of inter-connected processes. The production of fertilisers was the dominant business, and so the plant continued in full-scale production even when the cement market was depressed, but under-produced, even in high demand periods, if the fertiliser market was slow. ICI was strong enough to make the Cement Makers Federation accept this behaviour. The complex integration of the cement plant into ICI Billingham is described in detail in an article below.

The plant was designed from the outset for efficient water transport, necessary for bringing in chalk, and much product was shipped by water. The wharf was maintained for shipping product by ICI, although this function had disappeared by the time the plant closed. Situated in a major industrial area, its landward communications by road and rail were excellent.

In 1970, the replacement of the sulfuric acid process and the shut-down of the ammonium sulfate plant caused the closure of both sulfuric acid and conventional kilns. The sites were cleared fairly promptly. The cement plant area remains waste ground. The sulphuric acid plant site is now occupied by a municipal recycling and incinerator facility. The shafts of the anhydrite mine are capped and fenced off, but evidently still accessible, since the mine was proposed as a dump for low-level nuclear waste. The Wharram chalk processing plant is still in place, although derelict (see York Stories website and a remarkable video).

Please contact me with any relevant information or corrections. I am particularly interested in firmer dates and statistics.

Power Supply

The plant was initially powered by direct drive from diesel engines, but from 15/1/1907 the plant was run exclusively electrically using power purchased from the Grangetown power station of the Cleveland and Durham Electric Power Company. It was the first British plant to run solely on purchased power. The next was Humber in 1921.

Rawmills

Nine rotary kilns were installed: six conventional and three anhydrite process kilns:

Kiln A1

Supplier: Fellner & Ziegler
Operated: 10/08/1904-04/09/1929
Process: Wet
Location: hot end 448163,522211: cold end 448134,522186: entirely enclosed.
Dimensions:

Rotation (viewed from firing end): clockwise
Slope: ?
Speed: ?
Drive: ?
Kiln profile:

Cooler: rotary: metric 10.00 × 1.000 beneath kiln
Cooler profile: 0×1067: 8230×1067: tyres at 191, 7430: turning gear at 6287.
Fuel: Coal
Coal mill: indirect: initially Griffin mills, later (1924?) Krupp ball mill common to four kilns
Exhaust: natural draught direct to stack. A cyclone and ID fan were added to kiln 4 in 1928 as a pilot for those fitted to kilns B1 and B2.
Typical Output: 1904-1923 45 t/d: 1924-1929 52 t/d
Typical Heat Consumption: 1904-1923 12.5 MJ/kg: 1924-1929 12.45 MJ/kg


Kiln A2

Location: hot end 448167,522207: cold end 448138,522182: entirely enclosed.

Rotation (viewed from firing end): anticlockwise
Identical in all other respects to A1.


Kiln A3

Location: hot end 448171,522202: cold end 448142,522177: entirely enclosed.

Rotation (viewed from firing end): clockwise
Identical in all other respects to A1.


Kiln A4

Location: hot end 448175,522197: cold end 448146,522172: entirely enclosed.

Rotation (viewed from firing end): anticlockwise
Identical in all other respects to A1.


Kiln B1 (=A5)

Supplier: FLS
Operated: 20/10/1927-03/07/1970
Process: Wet until 08/1929 then semi-wet
Location: hot end 448220,522237: cold end 448237,522157: entirely enclosed.
Dimensions (from cooler ports): Metric 82.00 × 2.850B / 2.550CD
Rotation (viewed from firing end): anti-clockwise
Slope: 1/25 (2.292°)
Speed: ?
Drive: ?
Kiln profile (from cooler ports): -2200×2850: 22600×2850: 25000×2550: 82000×2550: Tyres 2200, 13600, 31000, 50100, 71700: turning gear 33700.
Cooler: Unax planetary 12 × 4.11 × 0.880
Fuel: Coal
Coal mill: indirect: Tirax ball mill: direct by Atritor from 6/1958
Exhaust: ID fan direct to stack: cyclone added before the fan in 1933: Lodge Cottrell electrostatic precipitator added 2/1939, shared with kiln 2 until 10/1947.
Typical Output: 1927-1929 210 t/d: 1929-1947 216 t/d: 1948-1959 221 t/d: 1960-1970 210 t/d
Typical Heat Consumption: 1927-1929 9.5 MJ/kg: 1929-1947 7.55 MJ/kg: 1948-1959 7.29 MJ/kg: 1960-1970 7.65 MJ/kg


Kiln B2

Supplier: Vickers Armstrong
Operated: 24/08/1929-02/12/1970
Process: semi-wet
Location: hot end 448210,522241: cold end 448228,522155: entirely enclosed.
Dimensions (from cooler ports): 288’4½” × 9’10½”B / 8’10½”CD (metric 87.90 × 3.010 / 2.705)
Rotation (viewed from firing end): ?clockwise
Slope: ?
Speed: ?
Drive: ?
Kiln profile (from cooler ports): -610×3010: 28956×3010: 30937×2705: 87897×2705: tyres at 7010, 22860, 39167, 56007, 72542, 85496.
Cooler: reflex “Recuperator” planetary 12 × 4.12 × 1.207
Fuel: Coal
Coal mill: Initially indirect by common ball mill: direct by Atritor from 6/1958
Exhaust: ID fan direct to stack: cyclone added before the fan in 1933: Lodge Cottrell electrostatic precipitator added 10/1947.
Typical Output: 1929-1947 247 t/d: 1948-1959 252 t/d: 1960-1970 245 t/d
Typical Heat Consumption: 1929-1947 8.05 MJ/kg: 1948-1959 7.97 MJ/kg: 1960-1970 8.2 MJ/kg


Kiln S1

Supplier: Vickers Armstrong
Operated: 05/1931 -04/1970
According to Moses (op cit) the acid plant was started on the backup sulfur burners 14/12/1929, and the kiln was lit on 10/2/1930, but the kiln made no viable clinker at all during 1930, despite running for some 1800 hours. As with other kilns (e.g. Humber, Kent) for the purposes of this work I date start-up from the time some sort of usable product was made, in this case after major modifications and overhaul, in May 1931. It should be noticed that it was practice on the Anhydrite Process plants to count as output only product that could be used in cement, significant amounts not meeting this criterion being dumped and written off. This is in distinct contrast to cement industry practice, where anything that emerges from the front of the kiln is classed as clinker by definition.
Process: Anhydrite
Location: Hot end (cooler ports) 448062,522606: Cold end (feed scoops) 447998,522619: entirely enclosed.
Dimensions (from cooler ports): 222’1”× 11’0”B / 9’0”C / 11’0”D (metric 68.58 × 3.353 / 2.743 / 3.353). Rawmix was fed to these kilns through scoops 7’6" from the cold end, so the effective length was really 214’7” (65.405 m).
Rotation (viewed from firing end): clockwise
Slope: ?
Speed: ?
Drive: ?
Kiln profile (from cooler ports): -584×2743: 6579×2743: 8103×3353: 25171×3353: 27000×2743: 50622×2743: 52451×3353: 67691×3353: tyres at 5512, 20752, 34468, 48184, 61900: turning gear at 32334: scoops at 65405.
Cooler: Reflex “Recuperator” planetary 12 × 12’0” × 3’0” (metric 12× 3.66 × 0.914)
Fuel: Coal
Coal mill: direct fired: Rema mill?
Exhaust: suction provided by acid plant blowers and scrubbed by acid plant gas cleaning.
Typical Output: 1931-1937 97 t/d: 1937-1945 127 t/d: 1945-1970 163 t/d
Typical Heat Consumption: 1931-1937 14.78 MJ/kg: 1937-1945 11.43 MJ/kg: 1945-1970 10.0 MJ/kg


Kiln S2

Location: Hot end (cooler ports) 448061,522597: Cold end (feed scoops) 447997,522610: entirely enclosed.
Operated: 12/1/1935-07/1970
Typical Output: 1935-1937 105 t/d: 1937-1945 126 t/d: 1945-1970 163 t/d
Typical Heat Consumption: 1935-1937 13.26 MJ/kg: 1937-1945 11.43 MJ/kg: 1945-1970 10.0 MJ/kg
Identical in all other respects to S1


Kiln S3

Supplier: Edgar Allen
Operated: 12/1954-10/1970
Process: Anhydrite
Location: hot end (cooler ports) 448075,522646: cold end 447969,522667: unenclosed.
Dimensions (from cooler ports): 353’0”× 13’0”B / 10’0”C / 13’0”D (metric 107.59 × 3.962 / 3.048 / 3.962)
Rotation (viewed from firing end): anticlockwise
Slope: 1/25 (2.292°)
Speed: 0.50-1.05 rpm
Drive: 113 kW
Kiln profile (from cooler ports): -610×3962: 28346×3962: 32004×3048: 96012×3048: 99670×3962: 107594×3962: tyres at 7010, 25070, 45491, 65151, 85344, 104242: turning gear at 50597
Cooler: Reflex planetary with ?12 tubes
Fuel: Coal
Coal mill: unknown: probably originally indirect fired using a Newells ball mill. By analogy with the conventional plant and Widnes, it was probably direct fired by Atritor from 1958.
Exhaust: suction provided by acid plant blowers and scrubbed by acid plant gas cleaning.
Typical Output: 251 t/d
Typical Heat Consumption: 9.9 MJ/kg



Sources::

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Data regarding the Billingham anhydrite process plant

This is a description of the plant as installed in the 1930s, and is included because of the special interest of the unusual process.

Anhydrite was crushed to 25 mm at the mine and brought to the plant by one 30 m and one 150 m conveyor belt. It was stored in two 950 t rawmill feed silos (square section, 18 m high). The mine also supplied the ICI ammonium sulfate plant, via an 800 m ropeway.

Clay of 25% moisture content was dried in a 28’× 5’7” (metric 8.53 × 1.702) gas-fired co-current rotary drier at 3.81 t/hr.

A separate drier (24’6”× 4’11”, metric 7.47 × 1.499) was used for coke (11% moisture, 3.86 t/hr) and sand (10% moisture, 1.53 t/hr).

The dried clay, coke and sand were stored in pairs of silos of nominal capacities 280 t, 165 t and 500 t. These fed two open-circuit four-chamber FLS tube mills of inside-shell dimensions 11.00 × 2.200 m. These turned at 18.1 rpm and drew 450 kW supplied through Symmetro gearboxes. Output was 17.3 t/hr of raw meal with 2% >90 μm.

The meal was elevated to four 300 t square section silos from which it could be withdrawn and elevated to a set of four small aerated mixers discharging into four 340 t square section kiln feed silos. These, when full (and if dischargeable – a big if), were sufficient for four days’ kiln run.

The meal was moved by dual conveyor sets to the sump of the scoops feeding the kiln. The kiln was as described above. The kiln house entirely enclosed the kiln section, and was laid out to accommodate two kilns, with Kiln 1 on the north side. The kiln was direct-fired, raw coal being supplied from an 85 t hopper.

Kiln product was stored in a 1400 t bunker with five discharge points feeding the aerial ropeway conveying it to the conventional cement plant.

The kiln exhaust was supplied with a pair of sulfur burners to maintain SO2 content during kiln light-up. Before the precipitators, there was a steel auxiliary stack (with no fan) to maintain minimum kiln draught during acid plant stoppage. The four in-parallel dust precipitators were placed before the gas cooling tower. Dust captured was returned directly to the kiln feed sump. Kiln exit temperatures were 750-840ºC and the precipitators functioned only as drop-out boxes.

The gases were next cooled in water-sprayed conditioning towers. The moist cool gas was cleaned using mist (wet) precipitators which removed essentially all the remaining dust, and most of the water. The water from the conditioning towers and mist precipitators naturally contained considerable amounts of dissolved SO2. The SO2 was reclaimed in a stripping tower with a counter current of air, the latter being then re-introduced into the main gas stream.

The gas now passed into drying towers, in which the remaining humidity was removed by washing with 98% sulfuric acid. The now dry gas contained SO2, CO2, N2 and free air, and further air was introduced in order to get the correct SO2/O2 ratio. The diluted acid from the driers was re-used downstream. The dry gas now passed through a set of parallel ID fans ("blowers") that provided the sole flow energy for the entire system, including the kilns.

The gas now passed under pressure into the four parallel catalytic converter/heat exchanger units. The heat exchanger used the exothermic heat of the reaction in the converters to pre-heat the gas to the required reaction temperature (400-410°C). The gas in which the SO2 had largely been converted to SO3 was now led into absorption towers which took up the SO3 in re-circulating 98% sulfuric acid, the stronger acid thus produced being diluted back to 98% by bleeding in diluted acid from the gas driers (above). The finished acid bled from this circuit was put though coolers prior to storage.

Units in parallel could be isolated for maintenance while the rest of the plant ran on, but isolation required insertion and removal of blanking plates, almost always involving short but complete shut-downs.

Acid was held in six 370 t storage tanks. Tail gas still contained some SO2 and was scrubbed with ammonia, producing a substantial amount of ammonium sulfate as a by-product.

With the installation of Kiln 2, most of the downstream plant was not extended. The first kiln had fallen so far short of its planned output (250 t/day clinker) that the second kiln was more a back-up than a doubling of capacity. The relaxation of raw meal fineness miraculously obviated the need for extra raw milling capacity.

The following article is mainly about aspects of the Billingham chemical complex unrelated to cement, but it emerges that the post-WWI development of the cement plant was entirely dictated by the needs of the broader complex. The sequence of events given is largely based in information in Parke, Reader, Readman and Turley. Large amounts of historical information reside at Teesside Archives, much of it (for no good reason) still embargoed.

Fertilisers and Cement from Anhydrite at Billingham

Early development of the area between Billingham and Haverton Hill

The Billingham (aka Haverton Hill) cement plant began its life in 1904 as the most efficient of the cement plants of Northeast England, all of which used chalk from the Thames/Medway area as their primary raw material. As the twentieth century began, this was an increasingly shaky economic proposition because chalk, which had originally been available at near-zero cost, had now became an expensive item, both in terms of supplier prices and transport costs. In the period leading up to WWI, most of the northeastern plants closed, and by the mid-1920s, only two were left. The Warren and Billingham plants had undertaken the considerable expense of installing the crushing and grinding equipment to replace chalk with local, much harder limestones. At this time, the plants were functional, but very vulnerable. However, the Billingham plant eventually received a long lease of life and survived another 45 years, as a result of its absorbtion into one of world's biggest chemical plants.

At the time when the cement plant was built, Haverton Hill was an area on the edge of the Teesside conurbation that was just beginning to industrialise. The site on Bamlett's Bight was selected by Casebourne & Co. Ltd because it had a Boulder Clay deposit close by, and a deep water wharf for landing Thames chalk. Casebourne's had also been involved in the launch of the Greatham Salt Works, a few miles north. The local salt industry had started in 1882 and by 1887 four salt works were operating to the east of Haverton Hill. Another salt works was established to the west of the village in 1891 - the Tees Salt Company. The cement plant took the land lot immediately east of this. These salt works were early ventures in what became a vast local chemical industry and obtained salt by pumping brine from the Permian evaporite deposits underlying the area. These had originally been discovered by the local iron industry in drilling for a water supply. Prospecting for salt in the area involved many borings, which proved a fairly consistent sequence in which salt was found below a layer of anhydrite (which, however, was not always identified as such in the logs). In fact the subsurface geology became very well known.

The cement plant was thus the second significant industry in the area west of Haverton Hill. In 1908, the British Chilled Roll & Engineering Co. started up over the road to the west. The rapid industrialisation during WWI included the Furness Shipbuilding Company's shipyard immediately to the east of the cement plant, and to serve the proliferation of industries, the North Tees Power Station was under construction - opening in 1921. The latter development was a decisive event.

During the war, the disruption of shipping, apart from disrupting chalk supplies to the cement plants, more importantly disrupted the supply of fertiliser chemicals, endangering food supplies. What is more, the major supply of natural nitrates, from South America, was also needed for the explosives industry. Alarm about this reached Government level.

The Ammonia and Nitrates Project

This dual problem led to separate committees being set up both by the Ministry of Munitions and by the Board of Agriculture and Fisheries. Both the Chemical Society and the Faraday Society submitted reports on new processes for obtaining ammonia and/or nitric acid, and the Nitrogen Products Committee was set up early in 1916, with finance, manning and facilities for research. Of several competing processes for "nitrogen fixation", the Haber process was favoured from the outset. In the Haber process, hydrogen and nitrogen gases in a 3:1 ratio are caused to react at high pressure, in the presence of a catalyst, to form ammonia. A semi-theoretical account of the process was published in 1907, so its feasibility was understood world-wide, but the technicalities of actual production had yet to be developed. However, by 1913, BASF (Badische Analin- und Soda-Fabrik AG), under the leadership of Carl Bosch, had developed a scalable manufacturing process.

With the war under way, it became clear to the Nitrogen Products Committee that, although the basic process was understood, British chemists would have to re-invent the wheel to develop the detailed technology. Undaunted by this, the Government promptly financed the setting up of bench-top research and the construction of a physical plant.

The laboratory work commenced at University College, London. For the physical plant, a 108 Ha site at Billingham was selected. The reason for selecting this location is curious. The committee said:

the original scheme required some 15 to 20 MW, and to save time and obviate the necessity of erecting a separate generating station it was decided to take 3-phase HT current at 6 kV, 40 Hz. It was this decision which practically determined the site chosen which is close to a new generating station, not yet finished, of the Newcastle Electric Supply Co. (note 1)

From this point on, the site was a done deal, and it was the task of the site engineers to make the plant fit in it. The process began in February 1918, with the erection of a few temporary buildings functioning as stores for odd pieces of equipment that were acquired, a workshop and groundwork for a number of items, notably gas holders. However, the war ended in November 1918, and by the end of the year, Government enthusiasm for the scheme had evaporated - it was either to be privatised or abandoned altogether. The larger chemical industry firms, having anticipated this development, had set up a loose consortium to do research and carry forward a Haber plant.

The biggest chemical firm at the time, and the most enthusiastic about the new process, was Brunner, Mond & Co. Their main business was alkali production, mainly by the ammonia/soda method, but they also had a large share in the Castner/Kellner electrolytic process. During 1919, they were involved in considerable wheeler-dealing with the Government and with other private companies. They were not at all keen on taking on the project alone, because they assessed it as very risky, and wanted partners. Their initial choice of prospective partners was focused on the likely practicalities of running a Haber plant: Vickers and Armstrong Whitworth (engineers) and Johnson Matthey (precious metal catalysts). Later, realising the need to spread the costs, they decided to also approach Explosives Trades (Nobel) and British Dyestuffs Corporation.

Those in Government still keen to keep the project going - mainly on the Munitions side - contacted Brunner, Mond directly, but Brunner, Mond turned down the first offer as too expensive. The government, however, had a card up its sleeve - it controlled the access to Germany. In Germany the Haber process had been refined to a high degree of perfection during the war, and BASF were manufacturing on a large scale at their plant at Oppau, opposite Mannheim on the Rhine. Brunner, Mond were desperate to see this plant. As they frankly suggested to the government in 1918:

Let's send a chemical commission and pinch everything they've got!. (note 2)

They had been allowed a flying visit in February 1919, which yielded only a vague impression of the size of the operation. In April 1919, a much more serious lengthy visit was organised.

The "Burglary"

A party of six chemists and engineers departed for Dessau, having made it clear to the Government that they would need "exceptional powers to have important items of plant dismantled and to make sketches and take measurements of internal parts". The plant was in the French military zone, and BASF were able to persuade the French not to enforce such co-operation, by threatening to lay off its workforce, probably triggering an insurrection. The French wanted a quiet life, and instead it was agreed that the delegation could go anywhere in the plant and stay as long as they liked, but they were not allowed to measure or sketch. At each section they visited they found that the plant had just been stopped. They could only view the plant from ground level because all access ladders had been removed. Gauges and instruments were removed or painted over. The delegation could only return to their lodgings each day, write down and sketch what they had seen, then compare notes, and plan to resolve their uncertainties the next day. This went on for five weeks. Their substantial notes and reports were placed in a locked railway wagon under armed guard for transportation home, while they travelled back by road. On arrival it was found that the contents of the wagon had been removed through a hole in the floor. The team then had to spend two months reconstructing their reports from notes in pocket notebooks.

Brunner, Mond kept their reports very secret, even from the Government, perhaps because they were pure gold, or perhaps because they were embarrassed about their poor quality, but in any case they aimed to give the impression that they had information of value. In fact there were fatal gaping gaps in their knowledge. However, the company were afraid of BASF's capabilities - a view, they discovered, also shared by their French competitor Solvay. They could not risk the prospect of being upstaged by BASF. So with Solvay's encouragement, Brunner, Mond returned to talks with the government to complete the ammonia project, at least on a modest scale. In September 1919 the Brunner, Mond board decided to put in a bid for the Billingham site, if only to stop anyone else from getting it. Attempting to keep the price down, their bid played up the idea that the move was "in the public interest".

The formation of SA&N

On 22/4/1920 a memorandum of agreement was signed between Brunner, Mond and the Minister of Munitions to form a new company entitled Synthetic Ammonia & Nitrates Ltd, with starting capital subscribed by Brunner, Mond and Explosive Trades (Nobel). The price to be paid by Brunner, Mond was £715,200 for which they would get the Billingham site and contents, all the information so far gathered, and various patents, licences and contracts, including the contract with the power company. The company was registered on 3/6/1920. During the previous month, Explosive Trades had backed out of the deal, so Brunner, Mond were left with a giant pig-in-a-poke. There was no alternative but to set about building the plant.

Brunner, Mond had already set up a research group early in 1920, and this acquired the knowledge and apparatus from the bench-scale work at UCL. This was developed at existing Brunner, Mond sites at Walsall, Northwich and Runcorn. The Castner plant at Runcorn produced pure hydrogen as a by-product and was selected for a pilot plant. As explained above, those charged with designing the plant held a dark secret - many key technical details for the successful operation of a Haber plant were still unknown, and there appeared to be no straightforward way of developing in a hurry techniques that at BASF had taken many years. By September 1920, the slow progress based on the sketchy intelligence from the Oppau visit was becoming noticeable at Board level. At this point, a deus ex machina descended upon the project.

BASF was at the time building a new, larger Haber plant, incorporating all the latest improvements developed at Oppau, at Merseburg, Upper Saxony. Two ex-BASF engineers - August Koebele and René Adler - arrived at Brunner, Mond headquarters at Northwich. The event was described thus by Reader (Vol. 1, p 364):

'(they said). . .they were trained in the Haber process at Oppau and then were transferred to Mersebourg (sic) to take charge of erection and putting into operation of Haber plant there'. They offered to sell 'all drawings, tests and other data', saying that they would go elsewhere if Brunner, Mond turned them down.

They wanted 1.5 million French francs. After careful assessment, the project leader commented:

Had these men been in our employ since we began the study of the process in April 1919, we should by now be manufacturing ammonia.

Following a very brief period of moral anguish, Brunner, Mond paid up in December 1920, giving K&A (as they were cryptically called) 0.5 million francs down with the promise of a further 0.75 million francs after 6 months commercial operation. Plans for the Billingham installation were immediately completely reorganised along the lines of the Merseburg plant. The Runcorn pilot plant ("Unit 1") first made ammonia on 21/5/1921, and the first ammonia production plant at Billingham ("Unit 2") started up on 24/12/1923.

The Billingham Haber process

The plant was very elaborate (note 3). The basic reaction of the Haber process is deceptively simple:

3H2 + N2 → 2NH3

The complexity derives from the processes required to make the starting materials cheaply and in the high state of purity required to avoid poisoning the catalyst. The nitrogen, famously, is obtained from air (hence "nitrogen fixation"). However, removal of oxygen by distillation was far too expensive (although it was considered and occasionally used in the early stages of development). The cheap means of oxygen removal was to consume it by burning a fuel. Hydrogen could be produced by cracking water with carbon. These two processes were already well known and cheaply conducted in the form of the Producer Gas/Water Gas reactions that were used to supplement town gas, and to produce gas fuel for gas engines. A hot bed of coke is swept successively with air and with steam. With air we get:

O2 + 2C → 2CO

so we end up with a mixture of carbon monoxide and nitrogen + inerts. With steam we get:

H2O + C → H2 + CO

The first reaction is exothermic, and the second is endothermic, so for the cyclic process to be self-sustaining, the first reaction has to be conducted 20-40% longer than the second. Both gas streams contain carbon monoxide, and the hydrogen : nitrogen molar ratio is 0.2:1 rather than the required 3:1. The gases are then passed over iron oxide, as done at gas works, to remove most of the coke-derived hydrogen sulfide The carbon monoxide is then mostly removed, and the hydrogen supplemented, by the reaction:

H2O + CO → H2 + CO2

This is carried out at 400-500°C over a doped iron oxide catalyst. The gases now contain a large amount of carbon dioxide, and small amounts of carbon monoxide and sulfur compounds. In the next stage the gases are pressurised to 5.6 MPa and washed with water. This removes most of the carbon dioxide, as well as most of the remaining sulfur compounds. Decompression of the wash water releases carbon dioxide which is used in various other processes, notably the sulfate plant. Some, after further purification, can be sold as Dry Ice. Next, the gas is compressed to 20 MPa, and washed with an ammoniacal copper solution. This removes nearly all the remaining carbon monoxide and sulfur compounds

The compressed gas is now in a condition where it is useable for ammonia formation, but in practice, in order to maximise catalyst life, a further three purification processes take place - firstly, a weak ammonia solution wash to remove the rest of the carbon dioxide, then an activated carbon filter to take the rest of the sulfur, and finally with a sacrificial ammonia catalyst to remove the last traces of carbon monoxide - the worst catalyst poison.

Finally combination of the gases takes place at 20 MPa and a temperature of 400-500°C when brought into contact with a doped iron catalyst. The reaction is exothermic and therefore self-heating. In accordance with Le Chatelier's Principle, the reaction is favoured by high pressure (because the volume is halved) and low temperature (because it is exothermic), so lower temperature gives a better equilibrium conversion, but also slows the reaction. Typically 20-25% conversion is obtained, so the ammonia is removed by water washing or cooling, this stage also serving to dissipate the surplus heat. The unreacted gas is then returned to the converter. The construction of the converter was a major technical challenge, since it must tolerate both high temperature and high pressure. The technique involved reacting the mixture in relatively light temperature-resistant vessels, enclosed within a much larger massive-walled "cold wall" pressure vessel. It was necessary to design from scratch the metallurgy of such simple items as holding-down bolts and pressure tappings.

Some of the ammonia was captured as anhydrous liquid, but the majority of the ammonia was handled as aqueous solution.

Ammonium Sulfate

It had always been the intention that ammonium sulfate should be the main ammonia product for the fertiliser market. Its production with sulfuric acid was excessively expensive, and Brunner, Mond had assumed that they would use the Merseburg Process (first employed by BASF at Merseburg in 1913). The process involves the double decomposition of a mixture of ammonium carbonate and finely-ground calcium sulfate in water to give ammonium sulfate and calcium carbonate, driven forward by the relative insolubility of calcium carbonate:

2NH3 + H2O + CO2 → (NH4)2CO3

(NH4)2CO3 + CaSO4 → (NH4)2SO4 + CaCO3

With impetus for the project mainly coming from the munitions side, Brunner, Mond had not considered the details of the process until the Billingham construction was under way. As mentioned above, the existence of a source of anhydrite was not a consideration when the Billingham site was selected, and evidently Brunner, Mond, if they knew the underlying geology at all, did not make the connection with their future raw material needs. The first sulfate plant, set up in 1923 using imported ammonia solution, used anhydrite purchased from quarries at Gotham, Nottinghamshire, Cumwhinton, Cumberland, and later the Long Meg mine. The inconvenience of this must have focused minds on the need for a nearer source, and the mass of local geological information was consulted.

A particularly attractive prospect was the anhydrite underlying the nearby Warren cement plant, which had been examined by the owner, Charles Taylor Trechmann, who was a bit of a geologist. The deposit was relatively close to the surface (less than 30 m down) and SA&N approached Trechmann in April 1923, offering to develop a mine on his site, for a consideration. Trechmann would operate the mine and sell exclusively to SA&N. The Warren plant had problems with raw materials, having, like Billingham, been forced to use a local limestone during the war - in their case a very hard marginal Carboniferous Limestone. SA&N offered to supply them with easily-processed sulfate mud as an alternative. The mine started production in March 1925, and continued producing until 21/6/1930. At Billingham, drilling to prove their own anhydrite began in April 1924.

A notable disadvantage of the Merseburg Process was the production of waste calcium carbonate (0.76 kg per kg of product). This was removed from the reaction mixture by vacuum filtration, then washed with water and filtered again to minimise the loss of ammonia and sulfate. It emerged as a gelatinous filter cake, containing varying amounts of ammonia, anhydrite, soluble sulfate and water (typically 20-35%) , referred to as "chalk" by the plant and as "mud" by its customers. A certain amount would be dumped at sea, but there was pressure to monetise it in some way. Farmers might be induced to take it as "agricultural lime", and this was later elaborated into the more acceptable "Nitrochalk" fertiliser. However, Brunner, Mond can't have been unaware that various chemical firms were disposing of their carbonate wastes in cement plants (e.g. Crosfield's, Ditton, Jarrow).

Developments at the cement plant 1920-1924

While all these expensive and momentous developments were taking place on the SA&N site, the ramshackle cement plant continued to function in its small way. The war disrupted its sea-borne supply of chalk from the Thames and Medway. The alternative was chalk by rail, using the nearest quarries on the Northeastern main line, in the Hitchin area. As the war progressed, such logistics drew the attention of the Government - in fact, the Ministry of Munitions - and, as at Warren, the plant was ordered to make arrangements to use raw materials closer to hand. This inevitably meant modifying the plant to grind much harder materials. The Billingham plant obtained the chalk quarry at Wharram, East Riding, which had the advantage that it was of dependable purity, although, as with all northern chalks, it was much harder than the Thames variety. It was not until January 1920 that the new plant was operational. In December 1920, the company changed hands: it was bought by a group the chief of which was John Hunter (note 4), who during the war had been Controller of Iron & Steel in the Ministry of Munitions. It is tempting to infer that this was a ploy to bring the plant within SA&N's sphere of influence.

The new company was called Casebournes Pioneer Cement Co. Ltd, although the Casebourne family was no longer involved. It almost immediately (January 1921) received a delegation from SA&N proposing that Casebournes make use of their "chalk" product when it became available (note 5). Bench-top investigations (never very informative) suggested that it should work, and when the sulfate plant finally got underway in June 1923, slurried sulfate mud was pumped to the cement plant. This was a failure; the pipeline blocked, but not before the cement plant had been flooded with the slurry.

Another development during 1923 was the elongation of the cement kilns. The four kilns were originally 30 m long with 2 m internal shell diameter; they were lengthened to 125 ft (38.1 m). This was probably done in order to accommodate the very wet slurry produced with sulfate mud, but a 15% increase in output was also claimed. From October 1923, the cake was conveyed to the plant by rail. For a month, attempts to use it were beset by problems associated with its minor components, resulting in a kiln feed that, if burnable at all, yielded very poor clinker due mainly to the unmanageable sulfate content. Sulfate melt-down could only be averted by intense reduction, and the plant reported blue mortar. By November, the cement plant suggested to SA&N that they might find some other outlet for their mud.

SA&N's ammonia production having started in December 1923, the production of sulfate mud proceeded apace, ramping up to 90 dry tonnes a day towards the end of 1924. With no outlet, this was dumped on site, the pile rising to over 12,000 tonnes. Improvements were made to the process in the form of finer grinding of the anhydrite and more thorough filtration. The cement plant was persuaded to take the mud again in May 1924, at a rate of 50 t/day. At this time, the plant was consuming about 270 t/day of chalk. A concerted effort to deal with the mixture led to a brief (4 days) run at 100% replacement in December 1924. In September 1924, rail deliveries of mud were commenced to Warren. Warren had a chalk demand of about 320 t/day, but during 1925, Casebournes consumed only about 25 t/day of mud, while Warren took 50 t/day. Even this was only feasible by SA&N analysing the mud on site and rejecting the majority prior to despatch.

Rapid Expansion and Amalgamation 1925-1928

Following the success of the first ammonia plant at Billingham ("Unit 2"), SA&N, then wholly-owned by Brunner, Mond, decided in April 1925 to embark on a programme of "indefinite expansion", commencing with the installation of larger Units 3, 4 and 5. The projected cost was - it was claimed - beyond Brunner, Mond's means, so SA&N went public on 24 June 1925. At this time, not entirely coincidentally, Casebournes began examining the possibility of expansion involving a complete re-build with modern plant. SA&N collaborated in the planning for this.

The major increase in capacity of ammonium sulfate production meant that there would be a corresponding increase in the amount of sulfate mud to be disposed of. Ensuring that the cement plant could accept this was critical for success. This meant that the quality of the mud had to be improved to the point where it could be at least tolerated. The chemical defects of the sulfate mud were:

Improvements had been made to the sulfate plant. Anhydrite had originally been ground in a peripheral-discharge ball mill with an air separator returning the oversize. In mid 1925, the ball mills were replaced with Sturtevant ring-roll mills, allowing a finer grind, but for Unit 3, closed-circuit Hardinge mills were adopted. These improvements were hoped to be sufficient to improve acceptability by the time the new plant was commissioned. However, the chances of success would be greatly improved if the cement plant could be made part of SA&N.

Early in 1926, samples of the proposed raw materials for a plant using only sulfate mud as its carbonate component were submitted to F. L. Smidth for expert assessment. FLS reported back in April 1926, saying that the mixture was viable. This information was required before the decision could be made to rebuild the cement plant. This required major re-financing, and a new company - Casebourne & Co. (1926) Ltd - was launched on 15 May 1926. A new kiln, capable of doubling the plant capacity, was promptly ordered from FLS. The uprated plant, if using sulfate mud exclusively, could absorb about 180,000 dry tonnes per annum of the mud. Although the plant had been able to use only small amounts of the mud to date, in November 1926 the company entered into a contract with SA&N for supply of 150,000 t/a of the mud.

A major development at the SA&N in 1926 was the completion of the drilling programme, and the commencement of sinking the two shafts for the anhydrite mine in September. The mine finally came into production in November 1927. The Billingham chemical complex gradually expanded in output and in scope of products. The basic expertise in high pressure catalysis gained from the ammonia plant was applied to other products, such as methanol, made by hydrogenation of carbon monoxide, and "oil from coal" by hydrogenating and re-forming coal. The expansion of the plant made it desirable to start generating electricity on site, to make up for shortfalls in supply from the local power station, However, this scheme was dramatically expanded in 1927, when it became necessary to come to terms with the new regulations - the Electrical Supply Act (1926) - which stipulated that, prior to grid connection, all electricity suppliers must generate at 50 Hz. The SA&N plant - at Government mandate - had been set up to use 40 Hz and so there was a choice between completely re-installing all their electrical equipment, or building their own 40 Hz plant. They chose the latter, and continued to run at 40 Hz (with backup from the power station by frequency converters) until the 1950s, when lack of replacement parts finally forced them to re-wire.

The expansion of fertilisers and the growing sophistication of the market necessitated phosphates, requiring sulfuric acid for their production. With the proving of the anhydrite reserve, in May 1926, a project was launched to produce sulfuric acid from anhydrite.

On 18 December 1926, Imperial Chemical Industries (ICI) was formed. This involved the amalgamation of the four biggest British chemical firms:

As a subsidiary of Brunner, Mond, SA&N became part of ICI, along with another 58 chemical plants around Britain. It is significant that a similar amalgamation had taken place in Germany a year before - the formation of I. G. Farben on 2 December 1925, and along with du Pont in the USA, the world's major competing chemical firms were all massive conglomerates.

The upgrade of the cement plant proceeded during 1927, The new kiln started up on 20/10/1927, and the new finish mill started on the 31st. This was followed with a concerted change to use of the sulfate mud. The history of % carbonate replacement with sulfate mud reflects the early unease followed by a dramatic change in commitment in December 1927:

yearBillinghamWarren
19230.30.0
19243.21.4
19258.919.7
192610.311.4
192710.427.5
192897.551.3
1929100.031.1
1930100.00.0
1931100.00.0

Following promptly on this change, Casebournes were in February 1928 taken over by ICI, becoming the "Casebourne Division" of the company. Casebournes was formally liquidated on 31/12/1943. February also saw the commencement of installation of a 550 m conveyor and 1.57 km ropeway to bring sulfate mud from the sulfate plant to the new washmills, and the decision to install a second new kiln. Kiln 2, provided by Vickers Armstrong, started up on 24th August 1929, allowing the four increasingly uneconomic original kilns to be shut down shortly afterwards. The mud ropeway was commissioned in November 1929. A modern finish mill building with three mills was built. ICI made sure that the commitment to sulfate mud was cast in stone by demolishing the chalk crusher building in July 1928, when the last Wharram chalk was delivered.

Sulfuric acid and cement from anhydrite

The prime function of the cement plant within the ICI organisation was now to consume its by-products. The project to make sulfuric acid from anhydrite was well under way by the time of the ICI takeover The Müller-Kühne Process chosen had been proved at I G Farben's Leverkusen plant, but - perhaps unknown in the UK - it had also been attempted at at least five other plants with no success, so it remained a technical challenge. The process produces Portland cement clinker as a by-product, and the availability of the cement plant to consume this was a key part of the economics of the project; a ropeway transferred the clinker to the conventional cement plant for grinding.

The faltering development of the sulfuric acid plant is described elsewhere. The acid plant was started up on sulfur burners on 14/12/1930 and the kiln was lit on 10/2/1931, but no viable clinker at all was produced during 1931. The Müller-Kühne Process was developed in Germany by Bayer, which, like BASF, joined I G Farben in 1925. As with the Haber Process, the technology had to be extracted from post-war Germany, and the long period in which production appeared impossible was only ended when ICI paid for a consultancy team from I G Farben, who promptly got the process running. Acceptable clinker was first sent for grinding in May 1932, and a second acid plant kiln was installed in Januarry 1935.

The supply of conventional clinker was by now reliable, due in part to the installation of slurry filters in 1929. In addition to providing improved fuel economy, these had the advantage of reducing the amount of soluble salts in the kiln feed. The plant thus became the first in Britain to employ the semi-wet process. There were three Rovac filters which were continuous vacuum filters with rotating circular filter plates, from which the cake was continually scraped. These fed the kilns directly, the rotation speed being used as the kiln's feed rate control. The vacuum filter technology was inefficient compared with later pressure filtration, but was standard equipment for filtration throughout ICI's chemical processes. Pressure filtration at the sulfate plant would have given better ammonia recovery, as well as a more acceptable cement plant raw material, but this was never implemented.

From 1935, the plant remained more or less unchanged, except for the addition of a further finish mill in June 1954, and a third, larger acid plant kiln in December 1954. The quality of the acid plant clinker was such that the plant instigated a policy of always blending it with conventional clinker - a policy that remained in place throughout the life of the plant, although after the installation of the third acid plant kiln, the majority of clinker produced was from the acid plant. At Whitehaven, the acid plant clinker was always ground undiluted.

Closure of the entire cement plant in 1970 probably brought forward an event that would have been inevitable in the energy crisis of the following decade, but it was primarily caused by a change in the operational strategy of the chemical plant. The old water gas process for hydrogen had been replaced by naphtha reforming in the mid 1950s. North Sea gas began to be available in 1968, and it was decided in 1969 to change hydrogen production to natural gas reforming:

H2O + CH4 → 3H2 + CO

This is conducted at (typically) 900°C and 2 MPa. The subsequent reactions are similar. The power plant was converted to natural gas fuel. Nitrochalk (using part of the sulfate mud) was dropped as a product. The production of ammonium sulfate was reduced in favour of nitrate, and the acid plant was converted to sulfur burning. This allowed closure of the anhydrite mine. A film made in 1972 by the Billingham Film Unit makes the rather far-fetched suggestion that the cement plants and anhydrite mill were shut down due to environmental concerns. Anyway, the chemical plant went from strength to strength (at least during the 70s and 80s) and the lost 350,000 tpa of cement was not missed.

Notes

Note 1: Parke, p 6.

Note 2: Reader, Volume I, p 328. The remark was made by Francis Arthur Freeth of Brunner, Mond to John Fletcher Moulton, a judge and Director-General of the Explosives Department. Moulton replied: " . . you must not propose a burglary to a Lord of Appeal. Go and see Sir Keith Price and let me hear no more of this." Price (also at the Ministry of Munitions) was evidently thought to have fewer scruples.

Note 3: The general arrangement of the initial plant is described in Parke, pp 79-80, along with photographs and drawings.

Note 4: John Hunter (8/11/1863-17/10/1936) was a "gray eminence" behind the Billingham project. He was MD of engineers William Arrol & Co Ltd. Some of his relatives, involved with Dalmellington Coal & Iron, were also part of the group. He has only red links in Wikipedia, and his obituary in The Engineer, although fairly detailed, makes no mention of his connection with Billingham. Who will write his Wikipedia article? I would do anything to improve knowledge of this individual, but I won't do that.

Note 5: Parke, p 75.