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PHASE 4 1906
In 1906 the No3 furnace was modernised and renumbered 2a, leaving only No1 and No2 as the original design. They switched from the old, small slag boxes on bogies to self tipping slag ladles with a much greater capacity together with other changes to the works not visible here. As the furnaces were driven harder through increased hot blast volume and temperature, the slag temperature increased (at tapping) and viscosity decreased. This would consequently outlaw the use of slag boxes. The added bonus was that the slag could be comfortably transported further distance to the slag dump on the shoreline with lower risk of a "sticker" in the ladle.
Note that the 3 tall Cowper stoves to the right of this picture served the No1A furnace out of view to the right. The skip hoist rises somewhat diagonally between two of the stoves.
The most striking feature is that the furnace was charged by a different mechanism to No1a. No2a required a more substantial hoist structure. This was only three years after the 1a furnace was blown in. Instead of a skip, running on rails, it was a much bigger round bucket suspended from the hoist rails.(1) This rebuild also introduced four gas off-takes surrounding the furnace top, which came together in one downcomer about half way down the stack. All evidence of pushing the furnace to a capacity of 1500 tons per week.
This is a bucket skip employed at Dowlais around 1900. I think it is safe to assume this was a publicity photo, possibly marking introduction of the gear, I sincerely hope the furnace wasn't on blast. At left, one chap is sat on the counterweight of the bell operating beam. Above, another is sat on the edge of the chute and above him is someone sitting on the lip of the bucket. Everyone else is sat on the top of the furnace. One of the advantages of this arrangement over the skip was that it was easier to ensure even distribution of the charge - the iron ore, limestone, and coke which is vital to efficient blast furnace operation.
Workington employed a larger version of this on the surviving No3 and No4 furnaces until closure. The bucket was rotated while being loaded at ground level to evenly distribute the burden.
Right is a later and more substantial version but serves to illustrate the principle.
Below is an example of how the newly employed slag ladles were tipped. This one was in Staffordshire. The locomotive shoved the ladle and carriage to the end of the line, the carriage wheels were scotched (2) the locomotive uncoupled and withdrew, while pulling on a chain running from the side of the ladle, around a pulley fixed to the carriage. As the locomotive slowly withdrew, the ladle tipped. It was counterbalanced to return to level when empty. I will devote a separate section to slag handling.
It wasn't unusual to find the ladle and the locomotive at the bottom of the tip after an accident. There is no record of it happening at Carnforth but it did happen at Barrow and Workington.
This is a hand tinted postcard from the Valentine's series. It pops up from time to time on ebay.
There are not many images that depict the furnaces from this perspective. It was taken from the entrance on Warton Road. The original blower house (right) has been modified. I will examine these changes in detail in the Provision of Blast section.
There is a long overhead crane gantry running the full length of the pig beds in front of the furnaces. All the raw materials, the coke, iron ore, and limestone were delivered, stored and discharged from the bunkers on the East side. At regular intervals, slag was tapped from the base of the furnace and ran in to ladles and hauled away from the West side. Then the molten iron was run in to pig beds where it was cooled. Recovery of the cooled pigs was a manual task but if several pigs were still joined to the sow (the ingoing runner) then it would need assistance from the crane to lift them out. Pigs might be broken off one by one manually or by machine. There is a solitary 3 plank wagon used to transport the pigs.
The elevated open structure to the left may have been an early form of cooling tower. Cooling capacity was uprated several years later with two substantial wood built cooling towers.
Below Several postcards survive from this period, all photographed from broadly the same spot (probably the A6 main road).
The original line of six furnaces has been reduced to four. From left to right:
Blower house with three tall arched windows and a water header tank on the roof.
Three hot blast stoves, a lift structure, and two original open topped blast furnaces (No1 and No2)
Two hot blast stoves (steelworks chimney beyond) and modernised No2a furnace (old No3) with bucket hoist.
Three hot blast stoves, modernised No1a furnace (old 4,5,and 6) with a diagonal orientated skip hoist.
Beyond the furnaces there are glimpses of the pig beds overhead crane gantry and lines of wagons in the storage sidings
In front of the furnaces a line of coke wagons on the high line and what looks like a locomotive in the shadow of 1A furnace.
A line of low sided open wagons on the exchange sidings. Possibly empties waiting to be hauled in to the works
This is a hand tinted copy of the same image. How would the artist know what colours to use? What did they know that would cause them to colour the wagons in reds and greys? Its not wrong, its intriguing.
NOTES
(1) It seems a little odd that a skip hoist should be employed on 1A and then a bucket hoist on 2a. It is not an obvious choice. In the course of future research it may become clear. A second bucket hoist was chosen for the final furnace rebuild so it must have become the preferred option. Incidentally, The three blast furnaces at Workington were split the same way. No 3 and 4 were bucket charged but No2 was charged by skip hoist. Paradoxically, No2 was the youngest (and largest furnace).(2) There were no brakes on slag ladle carriages. To secure a carriage in a stationary position, a wooden scotch (looking like a cheap, one piece cricket bat) was wedged between a wheel and the rail. It was a practice that continued at Workington right up until closure in the 1970s.NOTES
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