Invergordon Work - The Saltburn Conveyor

Invergordon Community Collage

The Saltburn Conveyer

The Saltburn Conveyor

Since the closure of the smelter in 1981 the demolition of the plant and the subsequent redevelopment of the site to an industrial park has proceeded with little notice or comment.

The demolition of the conveyor is indeed the removal of one of the last remaining landmarks of the smelter and it is true to say that the landscape of the north shore of the Cromarty Firth will be all the better for its removal. The conveyor, however, has a particular identity with the Highlands and its removal represents the end of a piece of engineering history.

The conveyor was of the Cable Belt concept and being 60" wide was in fact unique. It is not well known that the Cable Belt conveyor system was invented by an engineer working in Inverness in the late 1940s. He was Mr Charles Thompson and, with his partner Mr S Gordon (previously managing director of another world-renowned Inverness company - then Resistance Welders), he established the company called Cable Belt Ltd in 1949 in Inverness.
The first operating unit was installed for the National Coal Board at the Francis Colliery in Fife. It was 787 yards long and operated over a gradient of 1 in 4.

The principle behind the invention was to seaparate the driving forces from the carrying function of the conveyor. Charles Thompson achieved this by supporting the belt on two steel wire ropes. The design eliminated the need to drag the belt through troughing idlers and so eliminate significant drag forces and give much reduced power requirements and greater carrying capacities.

During the 1950s and '60s the Cable Belt conveyor continued to answer the requirements of the mining industry: first in the UK, where the National Coal Board was upgrading the old mines it had acquired. The Cable Belt system was used extensively by the NCB on the main trunk roads underground where having a long continuous belt conveyor with only one drive unit was most desirable. Then, as output increased in the coal mines, engineers looked for a way to improve the vertical shaft outlet. They drove inclined tunnels down from the surface to reach the coal which was also having to be worked at greater depths and the Cable Belt conveyor was the answer to this method as it offered a continuous flow for the increased output with a single drive conveyor having the drive located on the surface.

In the mid 1960s the company moved from Inverness to Camberley, Surrey, and embarked upon a programme of further technical development and expansion, particularly overseas. Then, in the late 1960s, the company joined a large engineering group, headquartered in London, to enable it to undertake further technical development and expansion. As part of the overall company expansion a network of overseas subsidiaries was formed which now function worldwide.

During the 1970s, Cable Belt developed the long overland applications where there is an increasing demand to carry bulk materials over long distances economically, in preference to trucks and rail haulage. In this field the Cable Belt system is now well established with single flight, single drive conveyors with lengths up to 25 km in operation.

Since its inception in Inverness in 1949 the Cable Belt system has proved its worth.

In respect of the Invergordon installation, it was designed to operate at 1,500 t.p.h. and the quayside facility specifically designed to give a totally enclosed transfer system from the bulk cargo vessels to the smelter silos. The ships were complete with self-discharging equipment also rated at 1,500 t.p.h.

Unfortunately, in the mid 70s, the ships were taken off the trans-Atlantic run and the replacement vessels were only equipped with grab discharge equipment and hence the notorious white clouds of dust became a common feature of the Saltburn jetty and the conveyor system was never called upon to handle discharge rates in excess of 600 t.p.h.

The conveyor was 6,670 feet long and operated at 350 ft/min (approx. 3 mph). It was driven by an electronic motor of 500 hp.

Throughout its operating life the conveyor handled almost 2 million tonnes of aluminium oxide (Alumina - the raw material) and over half a million tonnes of petroleum coke.

The entire alumina conveying complex was maintained and operated by a relatively small team of personnel; albeit over the years there were changes. It is interesting to note that of the "key players" all have remained in Ross-shire and now contribute to the success of other industries: John Russell (Isleburn), Ed Ross (Isleburn), Bert Stewart (Dalmore Distillery), Ken Macdonald (Trouw), Billy Macdonald (Trouw), Ken Macleod (Nigg Oil Terminal) and M Webb, who had the dubious privilege of commissioning the system on the first visit of the SS Richard in 1970.

The removal of a landmark- yes. The removal of an eyesore - yes. For some also the reminder of an association with an excellent asset whose origins were truly Highland, and a degree of sadness to see such a plant assigned to the scrapheap.



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