The final phase of Lead mining on Grassington Moor was 1780 – 1880 – the peak outputs during that time were 2,000 tons/yr in 1853 and 1856 but gradually dropping to less than 330 tons/yr and by 1877 all underground mining had ceased.
Leases were granted for reworking the many spoil heaps, for the high content of fluorite and barite, from 1917, onwards to Gregory then to Dales Chemicals Company (DCC) in the 1950’s via Fred Smith and his associates. The demand and price of barite and fluorite, were rising fast and DCC were anxious to get into production.
This was a major project, requiring electric power being taken high on the moor and a vast amount of plant to produce powdered barite and powdered fluorite – excavators, tipping waggons, large bunkers, log washer & vibrating screens, ball mill, atritors, filters and a floatation plant.
Flotation processes are based on the different surface wetability properties of materials In principle, flotation works very similarly to a ‘sink and float’ process, where the density characteristics of the materials, with respect to that of the medium where they are placed, are at the base of the separation. Flotation works in a different way in the sense that in a liquid medium, usually water, a “carrier” or reagent is introduced – air bubbles are created and the hydrophobic particles float and adhere to the bubbles with respect to the hydrophilic ones that sink.
The installation of all the equipment needed extra staff and skills to get the plant operational. We at Webster, Clough & Co.,Ltd in Bradford had often carried out boiler repairs and general engineering work at Linton Mill, Skyreholme Mill and Grassington Sanatorium (with it’s own power plant), so DCC were recommended to contact myself as General Manager.
Chemical flotation plants and the reagents used, are top secret to firms involved and it was certainly the case on Grassington Moor but we got on with the work we were there for and the whole set-up was a success.
Laporte Industries bought the plant for use on one of their sites, after DCC had exhausted all the spoil heaps on Grassington Moor and some other local sites.
© Les. Bloom C.Eng.
The featured image is Coalgrove Beck that was damned to provide a water supply. Water management on Grassington Moor was always a problem for industry: too much in winter and not enough in summer.
Workings from the west. The ore would be introduced for crushing on the right.
The flotation tank, lined with bricks. The metal strengthening bands that ran around the tank are now rusted through.
Inside this concrete building there are two metal hoppers.
The NMRS publication “Memoirs 1965” by Dickinson J.M. can be found by clicking here
A detailed explanation of The Fluorspar Benefication process can be found at 911 Metallurgist