952 



IRON 



John Gjers. They were of a circular form, and h.avo wrought-iron shells ; but unlike 

 ordinary kilns of this class, the shells are made of the same shape as the interior of 

 the kilns, so that there is a uniform thickness of 15 inches of fire-brick lining in all 

 parts. The shell and lining of each kiln rest upon an annular cast-iron entablature, 

 which is supported by eight hollow cast-iron pillars cast on the base plate. By this 

 arrangement a space for drawing the charge is left all round the bottom. The prin- 

 cipal dimensions of each kiln are: Internal diameter at the bottom, 14 feet; at the 

 largest part, 20 feet ; and at the top, 18 foot. The height from the base plate to the 

 top of the columns, 2 feet 3 inches ; the thickness of the entablature, 4 inches. Height 

 of the shell from the top of the entablature on which it rests to the level of the 1 

 diameter, 9 feet 2 inches; and from that level to the top of the shell, 12 feet 2 inches ; 

 total height of each kiln, from the base plate to the top of the shell, 22 feet. The 

 base plate is 2^ inches thick, and is 20 feet in diameter; it is cast in eight pieces, ami 

 rests upon brickwork, in which the air-passages arc formed. The cubic contents of 

 each kiln is 5,500 cubic feet. 



1227 



As will be seen in fig. 1227, each kiln is provided with a cast-iron central cone, 

 made in two pieces, so arranged that an annular space is left between them. This 

 cone spreads the calcined ore outwards towards the openings through which it can be 

 withdrawn, and it also acts beneficially in assisting to break up any large scars or 

 lumps partly fused together, which may happen to come down. The central cone 

 might, as far as the mere spreading action is concerned, be made plain and in a single 

 piece ; but the form shown in the figure has been adopted by Gjers with a view of, in 

 some cases, employing the annular space between the two cones for the admission of 

 waste gas from the furnace. Where the quantity of furnace-gas is not sufficient to be 

 applicable to this purpose, the double cones still furnish the means of giving a good 

 air-supply to the kilns. 



In the case of the particular kilns we are describing, the central cones are each 8 feet 

 in diameter at the bottom, and 8 feet high, and the air is conducted to them through 

 eight channels or flues formed in the brickwork at the base of each kiln. In addition 

 to these passages, there are a number of holes, fig. 1127, for the supply of air formed 

 in the outer shell. The kilns are placed at a distance of 25 feet apart from centre to 

 centre, and each is surrounded at the top by a gallery formed of wrought-iron brackets 

 covered with cast-iron plates. The galleries of four kilns ure connected with each other 

 at four points, the space between the kilns being bridged over with wrought-iron girders. 



Westman's Calcining Kiln. Kilns in which the waste gases of the blast-i'nnnce art- 

 applied to the calcination of ores are extensively used in Sweden, and have thence 

 been introduced into llussia and the United States. The improved form given to 

 these kilns by Westman, in which the gases are burnt by introduction of a blast of 

 air, is represented in the accompanying woodcuts. Fig. 1228 is a vortical section of 

 the kiln, the right half being taken through the lino A B, and the loft half through A. c 

 \nfig. 1229. Fig. 1229 shows horizontal sections at different heights along the lines 

 M N, K L,, and H i of Jiff. 1228. The shaft, a, is everywhere circular in horizontal sec- 

 tion. The raw ore is introduced through the shoot, b, which when not in use is 

 by a trap-door, and is delivered in the middle of the kiln through the moveaMo hop- 

 per, c. The opening, d, allows the throat, a' i', to be examined, and thus it may bo 

 seen whether the kiln is properly filled and the ore duly distributed, whilst it also 

 allows the ore to be re-arranged when necessary. The gas is conveyed through the, 

 circular main, e, and passing through the channel. </, enters tho furnace through tho 

 twelve passages, Jc; the supply of gas may bo regulated by means of horizontal slid- 

 ing valves. The air necessary for combustion is introduced through the tube, //, and 

 enters the furnace through twenty-four openings in tho hollow ring,/. The r 



