Who doesn't love a bit of Cwm Coke? Revisited recently to show @ultimateninjaworrier around, so thought I'd take the opportunity to reshoot everything at the same time.
One of my first reports on the forums was here, so I figured it's deserving of a fresh one considering I completely missed the Compressor House the first time.
Original Report (Here).
Much better lighting this time around, although somehow the weather was even worse than before... think I'm cursed to only be able to visit when it's pissing down with rain, rest of the day had been dry, and the drive to the hotel after was also mostly dry, go figure.
*This report went from a simple revisit to show someone around an old gem of an explore, to multiple visits to try and cover as much as possible, whilst piecing together how the site actually operated from the little that remains. Still haven't managed everything, but Secca floating about makes the more awkward areas more difficult to reach.*
Hopefully this isn't too long winded... Let's begin.
Drone Shot of the Site -
The History
Origins and Development
Cwm Colliery was established in the early 20th century, during the peak of the coal mining boom in South Wales. The region was rich in high quality steam coal, which was in great demand for shipping and industrial use.
The colliery was initially sunk in 1909 by the Great Western Colliery Company, which was one of several large companies operating in the area. The first sod was cut by Mrs C.H. James, the wife of the managing director, with Lady Margaret and Lady Mildred Bramwell also in attendance. The first coal was extracted in 1914.
Margaret Shaft
The Margaret Shaft was the deeper of the two, extending down to 2,384 feet 9 inches with a 24 foot diameter, with it being used as the Downcast Shaft. It was the main winding shaft, used for raising coal to the surface and for transporting miners in and out of the colliery.
The first manager of the pit was H. Bramwell, so presumably the shaft was named after Lady Margaret as she was family. Naming shafts after women was a common practice in the mining industry, often after the wife or daughter of the colliery owner or a significant local figure.
Mildred Shaft
The Mildred Shaft was slightly shallower, reaching a depth of 2,315 feet 9 inches with a 20 foot diameter, with it functioning as the Upcast Shaft. It was primarily used for ventilation and as an emergency escape route. It also served as a secondary access shaft. Like the Margaret Shaft, the Mildred Shaft was likely named after Lady Mildred.
A View Over the Colliery -
The workings were ventilated through use of a Walker type fan. Walker fans were centrifugal fans, a design known for generating high pressures, which is essential in deep mining operations. The fan operates by spinning a large impeller, which draws air into the centre and forces it outwards through a discharge outlet, creating a powerful airflow.
Underground Trackwork in Cwm Colliery -
Tunnel in Cwm Colliery -
Railway Connections -
The rail line serving Cwm Colliery and Coke Works was originally part of the Taff Vale Railway (TVR), one of the earliest and most significant railways in Wales, established with an Act of Parliament in 1836 with it opening in stages from 1840. The TVR was crucial for the transportation of coal from the South Wales Valleys to the ports in Cardiff and Barry.
The branch line serving Cwm diverged from the main line near Pontypridd and served not only Cwm Colliery but also other industrial sites in the vicinity. Cwm Colliery itself was accessed via a spur off this branch line.
As industrial activity at Cwm grew, particularly with the establishment of the coke works in 1958, the branch line became increasingly vital. It allowed for the efficient transportation of coal into the site and the distribution of coke and other by products out to other parts of the UK.
The coke works continued to be served by this line until its closure in 2002. Following the closure of the Cwm Coke Works, the remaining railway had no purpose so was lifted.
20th Century Operations
From a 1923 list, there were 1,043 men employed producing from the Four feet and Upper Five feet seams.
Powell Duffryn Steam Coal Company took the site over in 1928 as part of their acquisition of the Great Western Colliery Company with it becoming a subsidiary. At the time, the GWCC had three collieries, with 2,270 men employed.
The pit closed temporarily between June 1927-April 1929 due to poor trading conditions. In 1931, an 1,100 yard tunnel was driven to link Cwm with the nearby Maritime Colliery workings with the intention of diverting Maritime's output to the Cwm shafts.
By 1934, the pit was back in full production, with 100 men employed on the surface and 780 underground working the Six Feet and Four Feet seams. There were 36 coke ovens on the surface at this time of traditional Beehive design, which vented byproducts straight to the atmosphere.
During World War II, coal production was critical to the war effort, and collieries like Cwm were under pressure to maintain high output levels. However, the post-war period saw a gradual decline in the coal industry due to competition from other energy sources and the nationalisation of the coal industry in 1947.
The Modernisation Scheme
The £9m (~£218.5m today) modernisation and expansion of Cwm Colliery between 1952 and 1960 was quite extensive, with several major developments alongside the construction of the Cwm Coke Works. Some key changes were;
The Link to Coedely Colliery (1953):
A significant underground connection was created between Cwm and Coedely Colliery after five years of tunneling. This link allowed both collieries to collaborate more effectively by sharing resources and creating a more integrated coal production system.
Modernisation of the Winding Systems (1956):
The installation of fully automatic skips in the Margaret shaft, described as the largest of their kind at the time, was part of this upgrade. These skips were fitted with a dynamic braking system and automatic speed control, and they were capable of raising 12 tonnes of material or 80 men at a time with a winding cycle of 85 seconds.
The skip system had the capacity to handle 550 tonnes of coal per hour and was powered by a 3,000 h.p. motor. A new 1,800 h.p. winding engine was also installed in the Mildred shaft.
Merger with Coedely (1958):
Cwm and Coedely were merged into one entity, creating the largest colliery in the South Wales coalfield. With a goal to raise 5,500 tons of coking coal daily, the merge represented a major scaling of operations.
Expansion of Underground Infrastructure:
At its peak, the underground network at Cwm Colliery included a wide array of modern roadways, coal transportation systems, and large diesel locomotives. This allowed the efficient movement of coal to spiral chutes and rotary tipplers, enhancing overall productivity.
Cwm Coke Works
In 1958, Cwm Coke Works was built adjacent to the colliery. The coke works produced Foundry Coke, a crucial material for the Steel Industry, by heating coal in the absence of air. This was an essential process for the booming steel industry in South Wales, which was centred in nearby areas like Port Talbot.
The coke works became one of the largest in the UK, employing hundreds of workers and becoming a vital part of the regional economy. At its peak, it processed over 1,000 tonnes of coal daily, producing coke and valuable byproducts such as Town Gas, Benzene and Tar.
Decline and Closure
Investment in the site continued after 1960 along similar lines to other collieries under the NCB. This entailed further mechanisation and efficiency drives as technology advanced.
Despite its importance, the Cwm Colliery and Coke Works faced the same challenges as the broader coal industry in the UK. By the 1980s, coal mining was in steep decline due to the shift towards other forms of energy, changes in industrial practices, and the impact of the 1984-85 miners strike.
The coke works did benefit from one last significant investment under the NCB, with £20m (~£74.7m today) being ploughed into the site in 1981. This allowed a headcount of 325 men and left the site capable of producing 325,000 tonnes of coke annually although I'm unable to find any specifics as to what was changed.
Cwm Colliery ceased coal production on the 6th November 1986, following the pattern of closures across the South Wales coalfield. An estimated 80m tons in coal reserves remained underground. The site was mostly demolished and left empty after closure.
The Cwm Coke Works, however, was sold to a private venture (Coal Products Limited (CPL)) and remained in production, reflecting the ongoing demand for coke in the Steel Industry.
The site adapted to the closure of its associated colliery by sourcing coal from a range of other South Wales mines, with Tower and Maerdy Collieries being particularly significant suppliers. The combination of road and rail transport allowed the site to remain operational until 2002, long after the original colliery had ceased production.
Sources of Coal Post-1986
Tower Colliery
Located near Hirwaun in the Cynon Valley, Tower Colliery was one of the last deep coal mines operating in South Wales and continued production until 2008. Cwm Coke Works received significant quantities of coal from Tower Colliery, particularly because of its high quality anthracite coal, which was suitable for coke production.
My report on Tower is (Here)
Maerdy Colliery
Situated in the Rhondda Valley, Maerdy Colliery was another key supplier to Cwm Coke Works. Maerdy remained operational until 1990 and was known for producing high-grade coking coal. It supplied coal by rail to Cwm Coke Works during its last years of operation.
The Pit Bottom at Maerdy in 1975 -
Other Local Collieries
During the late 1980s and early 1990s, several smaller collieries in the South Wales region continued to supply coal to Cwm Coke Works. These included collieries such as Abernant Colliery near Aberdare, which remained open until 1988, and Cynheidre Colliery in Llanelli, which closed in 1989.
Coal continued to be brought in primarily by rail, but as the number of operating collieries dwindled and some smaller mines lacked direct rail connections, road transport became increasingly important. Lorries transported coal from nearby collieries to Cwm Coke Works, ensuring a consistent supply despite the challenging circumstances.
Post-Closure
From a few bits I saw around the site, I believe the site closed around June/July 2002, with the gas supply for the coke ovens being deactivated on the 26th June.
After its closure, the site of the coke works became derelict, a stark reminder of the decline of heavy industry in South Wales. It marked the end of almost a century of industrial activity on the site. When it closed, the plant was one of the last major coke works in the UK. The site underwent partial demolition in 2020.
Satellite Image from 2001 -
Satellite View Post Demolition -
Lots of reports on the site pre demolition, check out these from @Bikin Glynn (Here) and @Landie_Man (Here) to see it in all its glory.
In July 2023, £8m was secured from the Cardiff Capital Region Housing Viability Fund to demolish and decontaminate the site in preparation for redevelopment. If the work is not carried out, the developer (apparently Persimmon Plc) will have to repay this.
Whether or not anything goes ahead remains to be seen, with the site having had numerous planning applications in the past, with very little occuring.
It's been 15 months, and other than a slight increase in security (from my previous experiences, with fence repairs, patrols and Secca chilling out on the access road), nothing has happened thus far, so I wouldn't be surprised if the site remains in it's current state for a good while yet.
Overview of the Coking Process
Coal Selection
- The process begins with the selection of appropriate coal. The coal used for coking, called coking coal, is typically a blend of different types of bituminous coals, chosen for their ability to form a strong, porous coke suitable for use in blast furnaces.
Preparation of Coal
- The selected coal is crushed and mixed to achieve a uniform composition. This step ensures that the coal blend has consistent properties, which is important for producing high-quality coke.
Charging the Coke Ovens
- The prepared coal is then loaded into large, rectangular ovens. These ovens are often arranged in long rows called batteries. At Cwm Coke Works, like many other coking plants, these ovens were of the byproduct recovery type, where gases and other byproducts generated during coking are captured and processed rather than being vented to the atmosphere.
Heating (Coking)
- The coal is heated to very high temperatures, typically between 1,000 and 1,100°C (1,832 to 2,012°F), in the absence of oxygen. This heating process usually lasts between 14 to 36 hours, depending on the specific requirements and the type of coal being used.
- During heating, the coal undergoes pyrolysis, where it decomposes chemically. The volatile components, including gases (such as methane, hydrogen, and carbon monoxide), tar, and ammonia, are driven off, leaving behind the solid carbonaceous material known as coke.
Quenching
- Once the coking process is complete, the hot coke is pushed out of the oven and quenched with water or air to cool it down rapidly. At Cwm Coke Works, water quenching was the typical method used.
- Quenching also helps to prevent the coke from re-igniting when exposed to air and stabilizes its physical properties.
By-Product Recovery
- The gases and vapours driven off during coking are collected and processed. This process allows for the recovery of valuable by-products, such as coal tar, ammonia, benzene, and sulfur compounds. These byproducts can be used in various industries, including the chemical industry.
Screening and Grading
- After quenching, the coke is screened to separate it into different size fractions. Larger pieces are often used in blast furnaces for steelmaking, while smaller pieces can be used in foundries or as fuel for industrial boilers.
Use in Blast Furnaces
- The final product, metallurgical coke, is primarily used in blast furnaces to smelt iron ore. Coke serves three main purposes: as a fuel to generate the high temperatures required for smelting, as a reducing agent to help convert iron ore into metallic iron, and as a support material that maintains permeability within the blast furnace by keeping the charge of ore and flux well-aerated.
Cwm Coke Works Specifics
At Cwm Coke Works, the process followed the general coking steps, with some specific details related to the plant's design and operations:
Coke Ovens
The ovens at Cwm Coke were of the 'Horizontal Retort type', a common design in many UK coking plants, with these particular ones being manufactured by Simon-Carves, a key player in the coke and coal gasification field post WW2. These ovens were designed for continuous operation with mechanisation being a key part of the design. The coal was charged at one end and coke was discharged l from the other after the coking cycle.
Unlike more traditional Beehive ovens which just burn off the byproducts produced by the coking process, Horizontal Retort ovens incorporated the capture of all byproducts, reducing the environmental impact and increasing profitability through their sale.
The blending plant had a capacity of 4,500 tons between four bunkers whilst the service bunker could hold 3,000 tons. Three different coals were blended, with the bulk of the supply coming from the Cwm Colliery until it's closure.
Coking time was 26 hours, with the final product after quenching having a moisture content of 6-8%. The plant had a capacity of 1,530 tons per day with the coke passing through two hammer mills, each of which had a capacity of 160 tons per hour.
By-Product Recovery
The plant was designed to efficiently capture the gases and tars produced during coking, which were then processed in on-site chemical plants to produce a range of byproducts like ammonia, tar, and benzene.
Benzene, along with other volatile compounds, is typically recovered from the gas produced in coke ovens. The gas is condensed and separated into various chemical products, which is then further refined and used industrially.
The Coal Tar produced was sent to the Caerphilly Tar Distillation Works (also referred to as the Thomas Ness Tar Works) which was owned by Coal Products Ltd for distillation into pitch, creosote and other valuable substances used in industries like road surfacing and timber treatment.
The Town Gas produced was stored in either of two Gas Holders on site. A 1 million cubic feet holder stored gas which was then sold to the Wales Gas Board to feed the gas grid.
A smaller 250,000 cubic feet holder stored gas for use in the adjacent Cwm Power Station which was attached to the colliery. The power station generated electricity from two GEC Double Pass out Turbo-generators which took steam at a pressure of 400 psi at 800 degrees Fahrenheit. The first passout was at 130 psi and the second 25 psi. The boilers serving them ran at a pressure of 428psi at 810 degrees Fahrenheit.
The system was capable of generating electricity at 11kV, with it being used for the mine's 3.3kV supply and to power the Coke Works, with any excess being fed into the national grid.
The Explore
Gained access via the usual point, no Bridge Guardian in sight this time though, which was a shame!
Compressor House
We battled through the brambles and bog to reach the Compressor House, and it was well worth the effort. Probably the best of the remaining buildings on site.
Donkin Compressor, presumably related to Town Gas production -
Gauge -
View From Above -
Control Panel -
Acme Snaplock -
Moved outside on the dry side and headed up the stairs to the roof. Lots of pipework up here and a nice view over the Donkin Compressors and the Gantry Crane, although not a good view for photo purposes.
Pipework -
Headed down the other stairs and encountered even more bogginess which was a right pain to negotiate, especially in the pouring rain. Reached the 2nd compressor room which is unfortunately more stripped than the Donkin side although it does have a large bank of switchgear.
If ChatGPT is to be believed, the compressors this side were for generating compressed air, with the compressors being BroomWade VMD 1000 models.
VMD 1000 -
Gauges -
Fire Alarm -
Checked out the ruined building behind the Compressor House next, very little to see except for a control panel for some long gone machinery.
Did climb the cooling tower which was bordering on being lethally slippery, but the weather was so grim I didn't bother grabbing any photos. Had a quick look in the stores building but that's been completely gutted.
Boiler House/Loading Area
We made our way back up top at this point and started off the main part of the site with the front end of the Boiler House, didn't grab any shots in here though, not much to be seen other than the shot of all the pipes in the backroom.
Moved around for a look at the rail wagon loading area, still no way upstairs unless you can haul yourself up a dangling cable in one of the corners though. Would have tried sending the drone up for some shots, but of course the lovely weather prevented that, I didn't even bring it from the car this time around.
Headed into the rear end of the Boiler House in search of the little laboratory next. It remains in pretty much the same condition as a couple of years ago, surprising that nobody has nicked or smashed up the remaining chemical bottles.
Lighting provided courtesy of an Olight Marauder rather than a shit Amazon torch, massive improvement considering the lab is pretty much in complete darkness.
Coke Ovens
Coke Ovens Battery next. The machinery that runs along the length of the building are likely Chargers or Pusher Rams. These were either used to push coal into the coke ovens or to push the finished coke out of the ovens.
Considering their position in what remains of the battery, I'm going to assume the latter, with coke pushed into quenching cars for cooling.
If you look out of the windows/holes in the walls in here, you may notice rails running along the platform outside. I'm not certain, but I'm guessing they are related to the images in the link (Here).
Cwm, like many coking facilities, made use of specialized 'coke quenching cars' or 'charging cars'. Charging cars transport raw coal to the ovens for coking, while quenching cars carry hot coke from the ovens to a quenching tower, where it’s cooled with water. The rail system would have facilitated this internal movement, often coordinated closely with the pushers that load and discharge the ovens.
I've never realised before that each unit has Cwm embossed on it along with it's respective number.
I've never bothered to count them either, but we wandered end to end and it turns out there's a single intact staircase at the rail loading end of the complex which leads to a series of chambers underneath the ovens.
These chambers are numbered, with 118 being the highest, so presumably this correlates with the number of pusher rams above. We didn't walk back down this end as there are collapses courtesy of the demolition work, so we weren't sure if we could exit or not.
It was also rather moist, with some awesome reflections from the pipework all along the ceiling. Didn't capture a shot worthy of making the report unfortunately due to my lack of a tripod, so you'll just have to take my word for it 😂
Lighting -
Switchgear/Hoppers
Headed back up the way we came to get back out, making a beeline for the switchgear rooms and the site conveyors control panel. It's a shame the room is so small, makes it a pain trying to capture the entire thing.
On to the Vibrator Hoppers, of course going up the ladders onto the platforms and getting plastered in coal dust.
We were going to head to the workshops next, but Secca turned up for a nose around. I saw him before he clocked us, so we made a dash back towards the entrance. We decided not to bother waiting him out as we were starting to lose the light, and we had a 90 minute drive to the hotel, so we called it a day and headed back to the cars.
Continued...
One of my first reports on the forums was here, so I figured it's deserving of a fresh one considering I completely missed the Compressor House the first time.
Original Report (Here).
Much better lighting this time around, although somehow the weather was even worse than before... think I'm cursed to only be able to visit when it's pissing down with rain, rest of the day had been dry, and the drive to the hotel after was also mostly dry, go figure.
*This report went from a simple revisit to show someone around an old gem of an explore, to multiple visits to try and cover as much as possible, whilst piecing together how the site actually operated from the little that remains. Still haven't managed everything, but Secca floating about makes the more awkward areas more difficult to reach.*
Hopefully this isn't too long winded... Let's begin.
Drone Shot of the Site -
The History
Origins and Development
Cwm Colliery was established in the early 20th century, during the peak of the coal mining boom in South Wales. The region was rich in high quality steam coal, which was in great demand for shipping and industrial use.
The colliery was initially sunk in 1909 by the Great Western Colliery Company, which was one of several large companies operating in the area. The first sod was cut by Mrs C.H. James, the wife of the managing director, with Lady Margaret and Lady Mildred Bramwell also in attendance. The first coal was extracted in 1914.
Margaret Shaft
The Margaret Shaft was the deeper of the two, extending down to 2,384 feet 9 inches with a 24 foot diameter, with it being used as the Downcast Shaft. It was the main winding shaft, used for raising coal to the surface and for transporting miners in and out of the colliery.
The first manager of the pit was H. Bramwell, so presumably the shaft was named after Lady Margaret as she was family. Naming shafts after women was a common practice in the mining industry, often after the wife or daughter of the colliery owner or a significant local figure.
Mildred Shaft
The Mildred Shaft was slightly shallower, reaching a depth of 2,315 feet 9 inches with a 20 foot diameter, with it functioning as the Upcast Shaft. It was primarily used for ventilation and as an emergency escape route. It also served as a secondary access shaft. Like the Margaret Shaft, the Mildred Shaft was likely named after Lady Mildred.
A View Over the Colliery -
The workings were ventilated through use of a Walker type fan. Walker fans were centrifugal fans, a design known for generating high pressures, which is essential in deep mining operations. The fan operates by spinning a large impeller, which draws air into the centre and forces it outwards through a discharge outlet, creating a powerful airflow.
Underground Trackwork in Cwm Colliery -
Tunnel in Cwm Colliery -
Railway Connections -
The rail line serving Cwm Colliery and Coke Works was originally part of the Taff Vale Railway (TVR), one of the earliest and most significant railways in Wales, established with an Act of Parliament in 1836 with it opening in stages from 1840. The TVR was crucial for the transportation of coal from the South Wales Valleys to the ports in Cardiff and Barry.
The branch line serving Cwm diverged from the main line near Pontypridd and served not only Cwm Colliery but also other industrial sites in the vicinity. Cwm Colliery itself was accessed via a spur off this branch line.
As industrial activity at Cwm grew, particularly with the establishment of the coke works in 1958, the branch line became increasingly vital. It allowed for the efficient transportation of coal into the site and the distribution of coke and other by products out to other parts of the UK.
The coke works continued to be served by this line until its closure in 2002. Following the closure of the Cwm Coke Works, the remaining railway had no purpose so was lifted.
20th Century Operations
From a 1923 list, there were 1,043 men employed producing from the Four feet and Upper Five feet seams.
Powell Duffryn Steam Coal Company took the site over in 1928 as part of their acquisition of the Great Western Colliery Company with it becoming a subsidiary. At the time, the GWCC had three collieries, with 2,270 men employed.
The pit closed temporarily between June 1927-April 1929 due to poor trading conditions. In 1931, an 1,100 yard tunnel was driven to link Cwm with the nearby Maritime Colliery workings with the intention of diverting Maritime's output to the Cwm shafts.
By 1934, the pit was back in full production, with 100 men employed on the surface and 780 underground working the Six Feet and Four Feet seams. There were 36 coke ovens on the surface at this time of traditional Beehive design, which vented byproducts straight to the atmosphere.
During World War II, coal production was critical to the war effort, and collieries like Cwm were under pressure to maintain high output levels. However, the post-war period saw a gradual decline in the coal industry due to competition from other energy sources and the nationalisation of the coal industry in 1947.
The Modernisation Scheme
The £9m (~£218.5m today) modernisation and expansion of Cwm Colliery between 1952 and 1960 was quite extensive, with several major developments alongside the construction of the Cwm Coke Works. Some key changes were;
The Link to Coedely Colliery (1953):
A significant underground connection was created between Cwm and Coedely Colliery after five years of tunneling. This link allowed both collieries to collaborate more effectively by sharing resources and creating a more integrated coal production system.
Modernisation of the Winding Systems (1956):
The installation of fully automatic skips in the Margaret shaft, described as the largest of their kind at the time, was part of this upgrade. These skips were fitted with a dynamic braking system and automatic speed control, and they were capable of raising 12 tonnes of material or 80 men at a time with a winding cycle of 85 seconds.
The skip system had the capacity to handle 550 tonnes of coal per hour and was powered by a 3,000 h.p. motor. A new 1,800 h.p. winding engine was also installed in the Mildred shaft.
Merger with Coedely (1958):
Cwm and Coedely were merged into one entity, creating the largest colliery in the South Wales coalfield. With a goal to raise 5,500 tons of coking coal daily, the merge represented a major scaling of operations.
Expansion of Underground Infrastructure:
At its peak, the underground network at Cwm Colliery included a wide array of modern roadways, coal transportation systems, and large diesel locomotives. This allowed the efficient movement of coal to spiral chutes and rotary tipplers, enhancing overall productivity.
Cwm Coke Works
In 1958, Cwm Coke Works was built adjacent to the colliery. The coke works produced Foundry Coke, a crucial material for the Steel Industry, by heating coal in the absence of air. This was an essential process for the booming steel industry in South Wales, which was centred in nearby areas like Port Talbot.
The coke works became one of the largest in the UK, employing hundreds of workers and becoming a vital part of the regional economy. At its peak, it processed over 1,000 tonnes of coal daily, producing coke and valuable byproducts such as Town Gas, Benzene and Tar.
Decline and Closure
Investment in the site continued after 1960 along similar lines to other collieries under the NCB. This entailed further mechanisation and efficiency drives as technology advanced.
Despite its importance, the Cwm Colliery and Coke Works faced the same challenges as the broader coal industry in the UK. By the 1980s, coal mining was in steep decline due to the shift towards other forms of energy, changes in industrial practices, and the impact of the 1984-85 miners strike.
The coke works did benefit from one last significant investment under the NCB, with £20m (~£74.7m today) being ploughed into the site in 1981. This allowed a headcount of 325 men and left the site capable of producing 325,000 tonnes of coke annually although I'm unable to find any specifics as to what was changed.
Cwm Colliery ceased coal production on the 6th November 1986, following the pattern of closures across the South Wales coalfield. An estimated 80m tons in coal reserves remained underground. The site was mostly demolished and left empty after closure.
The Cwm Coke Works, however, was sold to a private venture (Coal Products Limited (CPL)) and remained in production, reflecting the ongoing demand for coke in the Steel Industry.
The site adapted to the closure of its associated colliery by sourcing coal from a range of other South Wales mines, with Tower and Maerdy Collieries being particularly significant suppliers. The combination of road and rail transport allowed the site to remain operational until 2002, long after the original colliery had ceased production.
Sources of Coal Post-1986
Tower Colliery
Located near Hirwaun in the Cynon Valley, Tower Colliery was one of the last deep coal mines operating in South Wales and continued production until 2008. Cwm Coke Works received significant quantities of coal from Tower Colliery, particularly because of its high quality anthracite coal, which was suitable for coke production.
My report on Tower is (Here)
Maerdy Colliery
Situated in the Rhondda Valley, Maerdy Colliery was another key supplier to Cwm Coke Works. Maerdy remained operational until 1990 and was known for producing high-grade coking coal. It supplied coal by rail to Cwm Coke Works during its last years of operation.
The Pit Bottom at Maerdy in 1975 -
Other Local Collieries
During the late 1980s and early 1990s, several smaller collieries in the South Wales region continued to supply coal to Cwm Coke Works. These included collieries such as Abernant Colliery near Aberdare, which remained open until 1988, and Cynheidre Colliery in Llanelli, which closed in 1989.
Coal continued to be brought in primarily by rail, but as the number of operating collieries dwindled and some smaller mines lacked direct rail connections, road transport became increasingly important. Lorries transported coal from nearby collieries to Cwm Coke Works, ensuring a consistent supply despite the challenging circumstances.
Post-Closure
From a few bits I saw around the site, I believe the site closed around June/July 2002, with the gas supply for the coke ovens being deactivated on the 26th June.
After its closure, the site of the coke works became derelict, a stark reminder of the decline of heavy industry in South Wales. It marked the end of almost a century of industrial activity on the site. When it closed, the plant was one of the last major coke works in the UK. The site underwent partial demolition in 2020.
Satellite Image from 2001 -
Satellite View Post Demolition -
Lots of reports on the site pre demolition, check out these from @Bikin Glynn (Here) and @Landie_Man (Here) to see it in all its glory.
In July 2023, £8m was secured from the Cardiff Capital Region Housing Viability Fund to demolish and decontaminate the site in preparation for redevelopment. If the work is not carried out, the developer (apparently Persimmon Plc) will have to repay this.
Whether or not anything goes ahead remains to be seen, with the site having had numerous planning applications in the past, with very little occuring.
It's been 15 months, and other than a slight increase in security (from my previous experiences, with fence repairs, patrols and Secca chilling out on the access road), nothing has happened thus far, so I wouldn't be surprised if the site remains in it's current state for a good while yet.
Overview of the Coking Process
Coal Selection
- The process begins with the selection of appropriate coal. The coal used for coking, called coking coal, is typically a blend of different types of bituminous coals, chosen for their ability to form a strong, porous coke suitable for use in blast furnaces.
Preparation of Coal
- The selected coal is crushed and mixed to achieve a uniform composition. This step ensures that the coal blend has consistent properties, which is important for producing high-quality coke.
Charging the Coke Ovens
- The prepared coal is then loaded into large, rectangular ovens. These ovens are often arranged in long rows called batteries. At Cwm Coke Works, like many other coking plants, these ovens were of the byproduct recovery type, where gases and other byproducts generated during coking are captured and processed rather than being vented to the atmosphere.
Heating (Coking)
- The coal is heated to very high temperatures, typically between 1,000 and 1,100°C (1,832 to 2,012°F), in the absence of oxygen. This heating process usually lasts between 14 to 36 hours, depending on the specific requirements and the type of coal being used.
- During heating, the coal undergoes pyrolysis, where it decomposes chemically. The volatile components, including gases (such as methane, hydrogen, and carbon monoxide), tar, and ammonia, are driven off, leaving behind the solid carbonaceous material known as coke.
Quenching
- Once the coking process is complete, the hot coke is pushed out of the oven and quenched with water or air to cool it down rapidly. At Cwm Coke Works, water quenching was the typical method used.
- Quenching also helps to prevent the coke from re-igniting when exposed to air and stabilizes its physical properties.
By-Product Recovery
- The gases and vapours driven off during coking are collected and processed. This process allows for the recovery of valuable by-products, such as coal tar, ammonia, benzene, and sulfur compounds. These byproducts can be used in various industries, including the chemical industry.
Screening and Grading
- After quenching, the coke is screened to separate it into different size fractions. Larger pieces are often used in blast furnaces for steelmaking, while smaller pieces can be used in foundries or as fuel for industrial boilers.
Use in Blast Furnaces
- The final product, metallurgical coke, is primarily used in blast furnaces to smelt iron ore. Coke serves three main purposes: as a fuel to generate the high temperatures required for smelting, as a reducing agent to help convert iron ore into metallic iron, and as a support material that maintains permeability within the blast furnace by keeping the charge of ore and flux well-aerated.
Cwm Coke Works Specifics
At Cwm Coke Works, the process followed the general coking steps, with some specific details related to the plant's design and operations:
Coke Ovens
The ovens at Cwm Coke were of the 'Horizontal Retort type', a common design in many UK coking plants, with these particular ones being manufactured by Simon-Carves, a key player in the coke and coal gasification field post WW2. These ovens were designed for continuous operation with mechanisation being a key part of the design. The coal was charged at one end and coke was discharged l from the other after the coking cycle.
Unlike more traditional Beehive ovens which just burn off the byproducts produced by the coking process, Horizontal Retort ovens incorporated the capture of all byproducts, reducing the environmental impact and increasing profitability through their sale.
The blending plant had a capacity of 4,500 tons between four bunkers whilst the service bunker could hold 3,000 tons. Three different coals were blended, with the bulk of the supply coming from the Cwm Colliery until it's closure.
Coking time was 26 hours, with the final product after quenching having a moisture content of 6-8%. The plant had a capacity of 1,530 tons per day with the coke passing through two hammer mills, each of which had a capacity of 160 tons per hour.
By-Product Recovery
The plant was designed to efficiently capture the gases and tars produced during coking, which were then processed in on-site chemical plants to produce a range of byproducts like ammonia, tar, and benzene.
Benzene, along with other volatile compounds, is typically recovered from the gas produced in coke ovens. The gas is condensed and separated into various chemical products, which is then further refined and used industrially.
The Coal Tar produced was sent to the Caerphilly Tar Distillation Works (also referred to as the Thomas Ness Tar Works) which was owned by Coal Products Ltd for distillation into pitch, creosote and other valuable substances used in industries like road surfacing and timber treatment.
The Town Gas produced was stored in either of two Gas Holders on site. A 1 million cubic feet holder stored gas which was then sold to the Wales Gas Board to feed the gas grid.
A smaller 250,000 cubic feet holder stored gas for use in the adjacent Cwm Power Station which was attached to the colliery. The power station generated electricity from two GEC Double Pass out Turbo-generators which took steam at a pressure of 400 psi at 800 degrees Fahrenheit. The first passout was at 130 psi and the second 25 psi. The boilers serving them ran at a pressure of 428psi at 810 degrees Fahrenheit.
The system was capable of generating electricity at 11kV, with it being used for the mine's 3.3kV supply and to power the Coke Works, with any excess being fed into the national grid.
The Explore
Gained access via the usual point, no Bridge Guardian in sight this time though, which was a shame!
Compressor House
We battled through the brambles and bog to reach the Compressor House, and it was well worth the effort. Probably the best of the remaining buildings on site.
Donkin Compressor, presumably related to Town Gas production -
Gauge -
View From Above -
Acme Snaplock -
Moved outside on the dry side and headed up the stairs to the roof. Lots of pipework up here and a nice view over the Donkin Compressors and the Gantry Crane, although not a good view for photo purposes.
Pipework -
Headed down the other stairs and encountered even more bogginess which was a right pain to negotiate, especially in the pouring rain. Reached the 2nd compressor room which is unfortunately more stripped than the Donkin side although it does have a large bank of switchgear.
If ChatGPT is to be believed, the compressors this side were for generating compressed air, with the compressors being BroomWade VMD 1000 models.
VMD 1000 -
Gauges -
Fire Alarm -
Checked out the ruined building behind the Compressor House next, very little to see except for a control panel for some long gone machinery.
Did climb the cooling tower which was bordering on being lethally slippery, but the weather was so grim I didn't bother grabbing any photos. Had a quick look in the stores building but that's been completely gutted.
Boiler House/Loading Area
We made our way back up top at this point and started off the main part of the site with the front end of the Boiler House, didn't grab any shots in here though, not much to be seen other than the shot of all the pipes in the backroom.
Moved around for a look at the rail wagon loading area, still no way upstairs unless you can haul yourself up a dangling cable in one of the corners though. Would have tried sending the drone up for some shots, but of course the lovely weather prevented that, I didn't even bring it from the car this time around.
Headed into the rear end of the Boiler House in search of the little laboratory next. It remains in pretty much the same condition as a couple of years ago, surprising that nobody has nicked or smashed up the remaining chemical bottles.
Lighting provided courtesy of an Olight Marauder rather than a shit Amazon torch, massive improvement considering the lab is pretty much in complete darkness.
Coke Ovens
Coke Ovens Battery next. The machinery that runs along the length of the building are likely Chargers or Pusher Rams. These were either used to push coal into the coke ovens or to push the finished coke out of the ovens.
Considering their position in what remains of the battery, I'm going to assume the latter, with coke pushed into quenching cars for cooling.
If you look out of the windows/holes in the walls in here, you may notice rails running along the platform outside. I'm not certain, but I'm guessing they are related to the images in the link (Here).
Cwm, like many coking facilities, made use of specialized 'coke quenching cars' or 'charging cars'. Charging cars transport raw coal to the ovens for coking, while quenching cars carry hot coke from the ovens to a quenching tower, where it’s cooled with water. The rail system would have facilitated this internal movement, often coordinated closely with the pushers that load and discharge the ovens.
I've never realised before that each unit has Cwm embossed on it along with it's respective number.
I've never bothered to count them either, but we wandered end to end and it turns out there's a single intact staircase at the rail loading end of the complex which leads to a series of chambers underneath the ovens.
These chambers are numbered, with 118 being the highest, so presumably this correlates with the number of pusher rams above. We didn't walk back down this end as there are collapses courtesy of the demolition work, so we weren't sure if we could exit or not.
It was also rather moist, with some awesome reflections from the pipework all along the ceiling. Didn't capture a shot worthy of making the report unfortunately due to my lack of a tripod, so you'll just have to take my word for it 😂
Lighting -
Switchgear/Hoppers
Headed back up the way we came to get back out, making a beeline for the switchgear rooms and the site conveyors control panel. It's a shame the room is so small, makes it a pain trying to capture the entire thing.
On to the Vibrator Hoppers, of course going up the ladders onto the platforms and getting plastered in coal dust.
We were going to head to the workshops next, but Secca turned up for a nose around. I saw him before he clocked us, so we made a dash back towards the entrance. We decided not to bother waiting him out as we were starting to lose the light, and we had a 90 minute drive to the hotel, so we called it a day and headed back to the cars.
Continued...
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