. Transactions . ed, of high gravity and very tcugh ;the third is porous and light, and constitutes about 25 per cent, of theentire product ; the second is between the other two in quality. Thefirst and second are broken fine and mixed with tar, and are used formaking slurry. The first only is used, mixed with burned dolomite,in making the hearth of the furnace. The third is not mixed withtar, and is only serviceable in making the repairs which are neces-sary after every casting. At Horde most of the dolomite is burned in a Mendheim ring-furnace, Fig. 1, so arranged that the heat may, by openi
. Transactions . ed, of high gravity and very tcugh ;the third is porous and light, and constitutes about 25 per cent, of theentire product ; the second is between the other two in quality. Thefirst and second are broken fine and mixed with tar, and are used formaking slurry. The first only is used, mixed with burned dolomite,in making the hearth of the furnace. The third is not mixed withtar, and is only serviceable in making the repairs which are neces-sary after every casting. At Horde most of the dolomite is burned in a Mendheim ring-furnace, Fig. 1, so arranged that the heat may, by opening or closinga valve, pass in or out of a compartment. The furnace here hadsixteen chambers. Fourteen is probably the least that it would beprofitable to construct. The bottoms of the compartments are made * Staid unci Kisen, vol. ii., i>. IJUo. BASIC REFRACTORY MATERIALS. 465 of the dolomte bricks, and the sides of ordinary fire-brick. Thedolomite is piled in pieces four to five tin es the size of the fist on. 1 the floor, so as to touch neither the sides nor the roof, and heatedgradually up to a white heat, and is gradually cooled, the dolomitevol. xiv.—30 466 .BASIC REFRACTORY MATERIALS. itself being used to store the heat necessary to bring the air up to aproper temperature for the combustion of the gases. The furnace isnot opened until all the material is cool enougli to be handled. Thefuel is poor coal, burned in a producer. This furnace has the ad-vantage of not only being a continuous one, but it may also be keptconstantly at work, if desired, at other things as well as the calcinationof the dolomite, for, as the temperatures are under control, and thechambers not very large, it may be used for treating a number ofsubstances at a time. The repairs to the furnace are small, and theamount of fuel and labor required are not large. Both the cupolaand the Mendheim furnaces are in use at Horde. The disadvantagesof the former have been found to be that it gives too much d
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
