The Metallurgy of Lead & Silver; Lead.- pt.II. Silver - Softcover

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1899 Excerpt: ... annealing and toughening even paving tiles may be made from ferruginous blast furnace slags. Thus, at Santiago de Chili § the slag is ladled from the slag pots into cast-iron moulds 6 inches square by 1 inch deep, each provided with a cover. After filling a lot of moulds they are covered and placed on a hearth, which has also a cover to anneal, a gentle heat being kept up so that the cooling operation may be slow. When the slag has cooled to a black heat, the moulds are lifted from the hearth and the tiles thrown into cold water to toughen them. The tiles are very hard and durable, and are worth, from £2 to £4 per 1000. Another entirely distinct method of making slag bricks for building is that in use at the Liihrmann furnaces, Osnabriick, Germany, where over 5,000,000 bricks have been made as follows:--The slag is granulated by a stream of water and then mixed with slaked lime in the proportion of 1 part of quicklime to 6 of granulated slag. The mixture is passed through a set of rolls and then through a mixing machine; the bricks are moulded in a machine which has a hopper filled by a labourer and which turns out the bricks automatically, subjecting each to 'Modem Copper Smelting, 7th Ed., 1895, p. 142. tEgleston, S.if.Q., vol. xii., pp. 112-117. ilbid., p. 189. §Braden, Trans. A.I.M.E., vol. xxvi., p. 52. H E. and M. J., Dec. 3, 1893. a great pressure by means of eccentrics. One pair of machines turns out 10,000 bricks per day, requiring 3 H.P. for the mixer and 8 H.P. for the moulder. The bricks are at first tender, and must be stacked carefully and protected from rain; but after six or twelve months exposure to air they become solid enough for building. The slag used at Osnabriick is, of course, the ordinary iron blast furnace slag...