Experimental Retorts at Pumpherston

The Pumpherston Oil Co. Ltd was one of the most prominent of the Scottish shale oil companies. Their success reflected good commercial judgement, plus a proper regard for the science behind the winning and processing of oil. The Pumpherston design of retort ( the heated vessel in which oil was released from shale) was progressively developed through experimentation and improvement, becoming universally adopted in the Scottish industry and widely used overseas.

The Pumpherston company was unique in constructing an experimental retort for the scientific study of the yields and chemistry of products from different sources of shale. Before investing in new mining operations it made sense to test that the seams of were sufficiently productive to justify new investment.

The experimental retorts appeared like a slender brick towers, separate but close to one of the commercial retort benches – massive brick-built slabs that contained many dozen retorts. This allowed conditions to be closely controlled and monitored without interence from neighbouring retorts. Shale retorting was a continuous process, with shale bing dropped periodically into the top of the vertical retort, while spent shale was continuously withdrawn at its base. The experimental retort was fed with the usual Pumpherston shale between each experimental session. Each experiment took several weeks, so it seems that 30-40 tons of a sample shale were required to obtain meaningful results

Two log books in our archive record operation of the experimental retort between 1902 and 1913, and from 1922 until 1929. Early experiments study the productivity of seams found in the Pumpherston company's many mines, and occassionally tests carried out on behalf of rival companies. The second record book, following the amalgamation of companies into Scottish Oils Ltd., dealt with sample batches from throughout the Scottish shale field.

Interesting, quite a few sample batches came from outwith Scotland, recognising Pumpherston's role as the world-leading centre for shale research. In June and July 1906 “shale from New Zealand” was fed into the experimental retort, while much of October and November of that year was devoted to analysing shale supplied by the Commonwealth Oil Corporation of New South Wales. In 1907 cauxite shale from France or Spain was tested, batches from New Brunswick in Canada went through in 1908, and Tasmanian shale followed in 1911. Subsequently several batches of shale from Burma and Manchuria were also tested. It might be expected that the Pumpherston Oil Company's investors also had business interests in these overseas operations, including the Paisley-based engineering firm of A &F. Craig, who supplied retort components world-wide.

A couple of experimental sessions also processed batches of Jurassic “Kimmeridge” shale from Dorset. The earliest test, in 1904, seems to have been associated with prospecting for shale at a number of sites north of Weymouth. A larger experiment was backed by the Admirality in 1912. A few years previously it had been decided that Britian's navy should be fueled on oil rather than coal, and as war loomed the Admirality were anxious to secure ample supplies of home-produced oils. The Kimmeridge shale was rich in oil, but contained a large sulphur content that proved impossible to remove during normal refining processes. When the oil was burned, a smelly, dirty flame formed acid residues that rapidly ate through boilers and piping. Plans were quickly abandoned.

It seems that the Dorset shale also disagreed with the Pumpherston experimental retort which had to be shut down, cleaned out, and then brought back to life with a charge of good clean predictable Pumpherston shale.