Comment
Author: Admin | 2025-04-28
The Origin and Progress of the Manufacture of Iron In Scotland - Statistics of the Trade - Effects of Over-speculation - Coatbridge and its Furnaces - Description of the Gartsherrie Ironworks - The Smelting Process - Invention of the Hot Blast and its Effect on the TradeThough the existence of ironstone in the Scotch coal measures was known many years previously, no attempt was made to turn it to account until the year 1760, when the Carron Ironworks were established. Only one kind of ironstone was then used — namely, the argillaceous or "clayband;" for the more valuable carbonaceous or " blackband " was not discovered till the beginning of the present century. These two varieties are known as the coal measure ironstones, and are found in all the great coal fields of Britain except those of Northumberland, Durham, and Lancashire. Though there are nineteen kinds of iron ore known to the mineralogist, it has been calculated that nine-tenths of the iron produced is derived from the clayband and blackband ironstones, the relative value of which is thus stated in a paper read before the Scottish Society of Arts by Mr Ralph Moore, Government inspector of Mines : — "Clay ironstones contain from thirty to fifty per cent. of metallic iron. Before being melted, they are mixed with coal, and calcined in kilns or large heaps, to drive off the carbonic acid gas, sulphur, and other impurities. This description of ironstone is found in seams or bands, and in nodules, throughout the whole of the measures, but is most plentiful in the lower part of the section. Blackband ironstone is a carbonate of iron, laminated with coal, generally in sufficient quantity for calcination without further admixture of coal ; and leaves, when calcined, a metallic coke containing from fifty to seventy per cent. of metallic iron. This description of ironstone is found in seams or bands in well-defined positions in the measures, but these are neither persistent in position nor equable in quality. Sometimes the seam is wanting altogether, or so thin as to be unworkable ; at other times, the coaly element so predominates that its metallic value is of small amount, while not unfrequently it contains nothing but coal. A good black band ironstone contains from two to eight per cent. of coal. When it contains more than twenty per cent. of coal, it is of little value
Add Comment