Acetone Recovery Houses :
Introduction...
Certainly the largest surviving built structures on site have to be the two Acetone Recovery Houses in Unit 1.
Their function was to receive evaporated vapour from cordite in the Stoving Rooms of the Stoving Houses and to
condense and distil it to produce acetone that could be returned to the Nitration Hills as a stabiliser for
nitroglycerine. It is possible that some nitroglycerine may also have come across in the vapour and also been
recycled and that water vapour had also to be separated from the two chemicals and discharged. Full details of
the processes used are not yet known.
Possible Processes for Acetone Recovery :
Examination of the available Internet information has disclosed two possible processes for treatment of the vapour
derived from the Stoving Houses. The problem was that nitric oxides, nitroglycerine and water, were liable to be
freed from the cordite as well. The solution was :-
- Absorbtion in Sodium Bisulphite solution followed by distillation of the resultant Acetate in the presence of
Sodium Carbonate solution. This is described by Cocroft and others in the Chilworth Gunpowder Works article in
the Journal of the Association of Industrial Archaeology.
- Direct low-pressure distillation of the vapours at a controlled temperature after condensing some impurities.
This low pressure distillation system, with the American nickname of 'Acetone Rocket', would account for the chequerwork
blowout panels in the upper section of the Acetone Recovery Houses, as a way to reduce or control a possible explosion.
The size of the Houses could argue for either process, although the second is more likely under wartime
conditions, where safety might have been compromised in the face of the need for rapid results.
Archaeological Evidence for the Acetone Recovery Houses :
From a map survey it was self-evident that there were originally two full-size and one half-size hall in each of the
two production Units. The full-size halls in Unit 2 were clearly flanked by two buildings that turned out to be Stoving
Houses, from reliable internal photography of facilities at ROF Holton Heath. The half-size hall was beside just the one
Stoving House.
The halls were manifestly designed to cope with the effects of fire or vapour explosion without destruction, by venting
the upper part of the halls through chequerwork brickwork clad with asbestos cement panelling. Wall-mounted lighting
systems similar to weatherproof incandescent bulb units were accessed externally, even at considerable heights, with the
power cables in external conduits. That argued for extreme care to avoid a spark that might trigger a vapour explosion.
The only volatile inflammables used at that date in explosives manufacture were ethanol, ether and acetone. From other
sources (notably site workers and the Acid Plant manager George Nicholson) it was clear that acetone was the substance
being handled. Similar light fittings exist on the Acetone Plant Tower, which was still standing opposite the Canteen
in June 2006.
In view of the pipe supports that run towards the Acetone Recovery Houses from the direction of the Boiler House, steam
(and possibly cooling water) must have been used to 'power' the processes in the buildings. Internet searches involving
'acetone recovery' produced plenty of hits for 'acetone recovery pots' and 'acetone recovery stills'. The Holton Heath
information has pictures of 'acetone stills' that would appear appropriate for the Acetone Recovery Houses.
Inferred Operation :
Vapour in the pipes from the Stoving Houses was received at the porch-like structures and probably driven by pump or
fan into some kind of condenser. This might have separated some water vapour as an impure condensate, the remainder of
the vapours going into a heater to be separated by low-temperature distillation. Nitroglycerine, if present, would be
next to condense, but would contain acetone as an impurity to keep it stable. Being more volatile than nitroglycerine,
it is probable that the acetone would have remained as a vapour and been routed into absorbtion towers. It is suggested
that recovered liquid acetone would have been used to absorb the acetone vapour by cascading down inside a tower, the
runoff at the tower base being cooled and a part recycled, the rest going for further purification by more heating,
absorbtion and cooling. The impure nitroglycerine would probably be taken to the Burette Houses and form part of the
nitroglycerine and acetone mix used in making more cordite.
The chief risks in this process would come from an escape of acetone that managed to be ignited. The floors were
probably kept wet and may have been coated in acid-resistant gritless asphalt to reduce the risk of sparks. Rising vapour
would be more likely to explode in the top of the building, the chequerwork construction and soft
Conclusions :
This page contains some verified information that has been sufficient to identify the buildings but not the exact
processes. Further information is needed before the details of the process can be completed.
