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Aluminium Oxide Abrasive Grit: Alundum by Jacobs's Process (Stansfield, 1914)
Alundum, the artificial corundum made at Niagara Falls by the Norton Company: bauxite, calcined to drive off its water, is fused in an electric arc furnace with about 5 per cent carbon, which reduces its iron, silicon and titanium to metal nodules; the fused alumina cools slowly into a hard crystalline mass that is crushed and sized as abrasive grit.
Bauxite melts near 2,000 °C and could not be melted commercially without the electric furnace.
Source: A. Stansfield, The Electric Furnace, 2nd ed. (1914), pp. 357-358. Picture: the book's Fig. 143, the Higgins alundum furnace.
Advanced
Unknown
Instructions
1
1
Calcine the bauxite
Calcine the bauxite
Calcine the bauxite in a rotary kiln to drive off its combined water.
Materials for this step:
Bauxite1 pieceTools needed:
Rotary Kiln2
2
Fuse in the arc furnace
Fuse in the arc furnace
Strike arcs between the electrodes and the carbon lining of the furnace bottom, then feed the calcined bauxite, with about 5 per cent carbon, in round the arcs; it melts and in time carries the current between the two arcs. Lower the water-cooled shell as the fused alundum builds up; the lower part solidifies as it fills.
Materials for this step:
Carbon1 about 5 per centTools needed:
Electric Arc Furnace3
3
Cool slowly
Cool slowly
When the shell is full, lift it with its contents off the base, put another shell in place, and let the alundum cool slowly so it grows into a hard, tough crystalline mass.
Tools needed:
Electric Arc Furnace4
4
Crush, separate and size
Crush, separate and size
Break up and crush the mass, separate the nodules of reduced metal mechanically, and size the grains for use as an abrasive.
Tools needed:
Rock Crusher
Sieve Set (Graded Mesh)Tools Required
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