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Cupola Furnace: the Common Foundry Cupola with a Drop Bottom (Bolland, 1893)
The founder's 'common cupola': an upright steel shell lined with firebrick, standing on four columns over a drop bottom, with a wind-box round it feeding the tuyeres and a charging door high up. Coke and pig iron go in at the top in layers; blast at the tuyeres melts the iron, which runs out at the spout.
Variable: the inside diameter, 24 to 84 in, which sets height, tuyeres, blower and charges. Fig. 9's 36 in cupola is 12 ft to the charging hole and takes 840 lb coke and 2520 lb iron on the bed, then 302 lb coke and 2718 lb iron per charge.
Source: S. Bolland, The Iron Founder Supplement (1893), pp. 34-54. Unknown: shell plate and brick sizes. Picture: Fig. 9 of the book.
Expert
Unknown
Instructions
1
1
Size the cupola
Size the cupola
Choose the inside diameter from the iron needed per hour: 10 tons in two hours (about 10,760 lb an hour) needs 48 in; 6 tons, 40 in. Make it tall enough that the gas burns before it escapes: a 50 in cupola is 14 ft from the base to the bottom of the charging hole, Fig. 9's 36 in one 12 ft. Above 60 in, keep 60 in at the tuyeres and widen above them, since the blast cannot reach the middle of a wider stock.
Tools needed:
Unknown Dimensions2
2
Build the shell, columns and drop bottom
Build the shell, columns and drop bottom
Build a steel shell with a charging hole and door, standing on four columns. Close the bottom with swing doors on a central prop, so the whole contents can be dropped at the end of a heat. Put a slag hole a little below the tuyeres and a spout at the bottom. Ours: mild steel plate, iron castings for the bottom doors. Not given: plate thickness.
Materials for this step:
Mild Steel Plate1 shell, charging door
Iron Castings1 drop-bottom doors
Unknown Metal1 columns, prop, spoutTools needed:
Arc WelderUnknown Dimensions3
3
Fit the tuyeres and wind-box
Fit the tuyeres and wind-box
Ring the cupola with a wind-box feeding the tuyeres, with a main blast pipe sized from the table (good for runs up to 100 ft). Tuyere area grows with the diameter: a 24 in cupola needs the area of 1 1/2 round 6 in tuyeres (or two flat ones 10 1/2 x 2 in), a 60 in about 13 1/2 (or eight flat 16 1/2 x 3 in), an 84 in 31 (or sixteen flat 16 x 3 1/2 in). Never reduce the tuyere area. A 42 in cupola takes a No. 3 Root blower and a 6 h.p. engine.
Materials for this step:
Mild Steel Plate1 wind-boxUnknown Metal1 tuyeres, blast pipeTools needed:
Arc Welder
Air Blower4
4
Line it with firebrick
Line it with firebrick
Line the shell with firebrick, every brick rubbed well down on the next and fitting the shell closely, set in mortar of the same nature as the bricks. A good lining lasts one to two years if the melter mends it each morning with thin coats of daubing, keeping its first shape. Ours: fireclay bricks and refractory clay mortar.
Materials for this step:
Fireclay Bricks1 lining
Refractory Clay Mortar1 setting and daubingTools needed:
Trowel5
5
Make the bed and melt
Make the bed and melt
Ram a sand bottom so it lies about 10 in below the tuyeres. Lay the fuel bed, about 22 in of coke above the tuyeres (840 lb in Fig. 9's 36 in cupola), and the first iron (2520 lb), then alternate charges of coke and iron (302 lb and 2718 lb). Blow: about 30,000 cubic feet of air melts a ton of iron. On long heats flux with white marble chips and draw the slag off at the slag hole. At the end, drop the bottom.
Tools needed:
Sand
Metallurgical Coke
Pig Iron IngotsAir BlowerMaterials
5- 1 wind-boxPlaceholder
- 1 drop-bottom doorsPlaceholder
- 1 tuyeres, blast pipePlaceholder
- 1 liningPlaceholder
- 1 setting and daubingPlaceholder
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