Ubufatanye
UBUHANZI
UBWIZA N'UBUZIMA
UBUKORIKORI
UMUCO N'AMATEKA
IMYIDAGADURO
IBIDUKIKIJE
IBIRIBWA N'IBINYOBWA
UBWUBATSI BUSUBIRA INYUMA
UBUMENYI
SIPORO
IKORANABUHANGA
IBYAMBARWA
Electric Arc Furnace: the Héroult Series-Arc Steel Furnace (Stansfield, 1914)
Héroult's steel furnace: a tilting hearth like an open-hearth furnace, lined with dolomite, with two carbon electrodes coming down through the roof. The current goes down one electrode, arcs into the slag, passes through the molten steel and arcs back up the other, so the heat goes straight into the metal.
Result: an electric steel furnace about 7 x 4 ft inside for a 3 ton charge, run at about 350 kW and 110 V.
Source: A. Stansfield, The Electric Furnace, 2nd ed. (1914), pp. 115-116, 214-216. Unknown: case and tilting gear details, electrode size. Picture: a drawn diagram (Fig. 93 is blank in the scan).
Impuguke
Unknown
Amabwiriza
1
1
Build the case and lining
Build the case and lining
Build the furnace in a steel case on a tilting mounting, about 7 x 4 ft inside, with charging doors at the ends. Line it with dolomite bricks and crushed dolomite; dolomite or magnesite on the hearth, which allows strongly basic slags. Ours: mild steel plate. Not given: the case and tilting gear, the bricks' making.
Ibikoresho by'iyi ntambwe:
Ikibaho cy'icyuma cyoroheje1 case
Dolomite (ishwagara irimo manyeziya)1 lining and crushed dolomite
Amatafari ya magnesite1 hearth, if magnesiteIbikoresho bikenewe:
Imashini isudira ikoresha umuriro w'amashanyarazi
Umwiko w'umwubatsi
Ingano zitazwi2
2
Make the removable roof
Make the removable roof
Make the roof of silica brick, covered with steel plates and given eyes so it can be lifted off. Between the two electrode holes use bronze plates instead of steel, because steel there would raise the inductance of the AC circuit. Fit water jackets round each electrode hole for a close fit, so less heat escapes and the electrodes do not burn in the air. Ours: copper tube for the water jackets. Silica brick has no head here.
Ibikoresho by'iyi ntambwe:
Ibikoresho bitazwi1 silica brickIkibaho cy'icyuma cyoroheje1 roof plates
Urupapuro rwa buronze1 plates between electrodes
Umuyoboro w'umuringa1 water jacketsIbikoresho bikenewe:
Imashini isudira ikoresha umuriro w'amashanyarazi
Icyuma Cyivumbura Gihagaze
Amazi3
3
Hang the electrodes
Hang the electrodes
Use two vertical carbon electrodes, square in section. Carry each in a holder on an arm supported by the furnace itself, so its height does not change when the furnace tilts: four contact pieces round the electrode, drawn tight by a steel strap and a screw in the arm, with the cable bolted to them. Raise and lower each electrode separately, by a regulator controlled by the voltage between it and the metal. Not given: electrode size, the regulator's build.
Ibikoresho by'iyi ntambwe:
Electrode ya karubone2 electrodes
Icyuma kitazwi1 holders, arms, contact piecesIbikoresho bikenewe:
Icyuma Cyivumbura Gihagaze4
4
Melt and refine a charge
Melt and refine a charge
Charge steel scrap with some iron ore and lime. Keep each electrode a little above the slag, leaving room for its arc. Regulate the current by hand while the scrap melts, then switch to automatic; full power only after about an hour. Pour off the slag and make a second, then a third, with lime and a little sand and fluorspar, before the final additions. At La Praz this took about 350 kW at 110 V: 5 hours for 1.25 tons of low-carbon steel, 8 hours for 2.33 tons of high-carbon steel. Not given: the electric supply.
Ibikoresho bikenewe:
AmaziIbikoresho
8- 1 roof platesUmwanya
- 1 lining and crushed dolomiteUmwanya
- 1 hearth, if magnesiteUmwanya
- 1 silica brickUmwanya
- 1 plates between electrodesUmwanya
- 1 water jacketsUmwanya
- 2 electrodesUmwanya
- 1 holders, arms, contact piecesUmwanya
Ibikoresho by'Ibishushanyo Bifitanye Isano
Iki gishushanyo gikora
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