Bute & Mwyndy Iron Ore works

Account of 1874 visit of Institute of Mechanical Engineers to Bute & Mwyndy Iron Ore mine published on Grace’s guide. This text is published under the creative commons Sharealike licence

“In returning from Landore to Cardiff, the Members visited the Mwyndy Iron Ore Mine, near Llantrissant, where they were received by the Manager, Mr William Vivian, who gave a description of the mine, and an account of the early opencast mining for iron ore and the manufacture of iron with charcoal, which were carried on in that locality several hundred years ago, until prohibited by an act of parliament forbidding the further use of the neighbouring woods for the requisite supplies of fuel; and a specimen of iron of excellent quality was shown, which had been produced at the time of those early workings, the name “Mwyn-dy” meaning “mineral house.”

About sixteen years ago a discovery of ore in the adjoining property led to the finding of ore in this mine also, and workings were commenced upon it. The deposit consists of brown haematite iron ore, occurring in a large bed or mass, between the carboniferous limestone on which it rests, and a bed of conglomerate. It lies immediately south of the edge of the South Wales coal basin, the thin shales overlapping the limestone close to the ore. The bed of ore was in some places from 35 to 40 ft. thick, and it dips north at an angle of about 45 degrees.

Like most other deposits of hematite iron ore in the same formation, it is found to be very irregular, large masses of ore being suddenly cut off by intervening bosses of limestone. This necessitates the employment of not less than one third of the miners upon “dead work,” exploring, and making communications for ventilation and for the conveyance of the ore; the total number of men employed is about 280.

The mine is worked both opencast and by mining underground, the extent of the workings being very considerable. The vertical depth to the present deepest point is 280 ft. from surface; and the water is pumped by two engines, each of which in winter raises upwards of 1,000 gall. per min., one of them being arranged to work on the dip. The ore is very variable in hardness, and a great deal of it requires blasting; from the levels it is brought out by horses to the vertical shafts and inclined planes, and on reaching the surface is tipped direct into the railway wagons, if sufficiently pure; but if not, it is first dressed by hand labour, being broken by hammers and then picked by hand to separate the iron pyrites and other impurities.

The total quantity of iron ore raised and sold has been over 620,000 tons, and the mine is at present in active work, yielding about 5,000 tons of ore per month. The quality of the ore is useful, yielding from 45 to 48 per cent. of metallic iron; it contains some silica. This and the Bute mine adjoining are the only hematite iron mines of importance in the district, and they possess the advantage of being within easy distance by rail from many of the South Wales blast furnaces. The Members were invited to refreshments at the mine by the Mwyndy Iron Ore Company; and returned in the evening by special train to Cardiff.”