of this metal; while Norway and Switzerland came next in producing
capacity, with 15,000 tons to their credit.
As regards further development of the producing capacity of the works located in the United Kingdom, the British Aluminium Co., which had already developed 25,000 H.P. from water-power at Foyers and Kinlochleven in Scotland, was in. 1921 seeking to obtain the necessary parliamentary sanction for developing the much greater water-power of the Lochaber district of Inverness-shire.
Concerning the use of aluminium chloride in place of the oxide for the electrolytic bath. Weaver, in U.S. patent No. 1,297,946 of March 1919, states that if aluminium chloride be fed into a bath con- taining sodium and aluminium chlorides in the molten condition, at such a rate that the molten chloride is replaced as fast as it is decom- posed by the current, the process can be made a continuous one; and the aluminium and chlorine, which are the two products of the electrolysis, can be separately drawn off. An apparatus is described in the patent, by which this method can be carried out.
The application of aluminium has grown enormously in recent years. One very large and increasing field of the metal is in the electrical trade, in which it is used for transmission lines, bus bars, field coils and windings, etc., etc. Its applications in the motor-car industry are well known, for not only is it employed in sheet form for gear and crank cases and for body work, but it is also employed largely for engine castings. Aluminium is being used to an ever- increasing extent in the chemical, brewing, sugar-refining, mar- garine, dyeing and soap industries, and the manufacture of cooking utensils affords another large outlet for the metal.
carbide are recognized, and the attempts to apply carborundum wheels to the grinding and finishing of fine steel goods have ceased, the artificial abrasive industry is on a very sound footing.
Silicon carbide is intensely hard and very brittle, and it is most suitable for grinding and finishing similar materials such as cast iron and marble, and for the finishing of leather goods; while arti- ficial corundum has taken the place of the natural variety (emery) where it has been found more suitable than carborundum.
Brass and Bronze. There have been many attempts in the past to apply electric methods of heating and refining to the melting and casting of brass. Until recent years none of these attempts were successful, but during the World War a large amount of experimental work was carried out in America with various types of electric furnace, and the difficulties that surround the electric melting and refining of brass and bronze appeared in 1921 to have been overcome.
At the commencement of the World War, there were, accord- ing to H. W. Gillett of the U.S.A. Bureau of Mines, no electri- cally heated brass furnaces in commercial operation in the United States. By the end of 1919 there were 40 American firms using or installing such furnaces, and over 100 of these were in opera- tion. One brass-rolling mill is stated to have installed 30 fur- naces, though these were chiefly of small capacity; one smelting
TABLE I.
World's Production of Bauxite, (long tons)
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1913
1914
1915
1916
1917
1918
1919
United Kingdom British Guiana India France Hungary Italy Spain United States
6,055
1,184 304,323
6,840 210,241
8,286 5H
3,843 219,318
",723
876
55,6i4 58,118 5,805
297,041
10,329
750 104,493
8,744 425,100
14,724 2,037 1,363 "8,973
7,664 568,690
9,589 4,199 1,192
7,675 453 605,721
9,221
1,682 160,820
2,924
1,751 376,566
TABLE II.
Estimated World's Production of Aluminium, (long tons)
United Kingdom
7,500
7,400
7,000
7,600
7,000
8,200
8,000
Canada
6,000
6,500
6,000
7,500
8,000
8,000
8,000
Austria
2,000
2,000
France*
13-283
9,803
5,920
9,447
10,886
11,826
12,000
Germany
1,000
1,000
1,000
8,000
20,000
25,000
12,000
Italy*
860
922
889
. 1,108
1,712
1,687
2,OOO
Norway
2,000
4,000
8,000
12,000
15,000
15,000
IO,OOO
Switzerland
10,000
15,000
10,000
12,500
15,000
15,000
15,000
United States
29,000
41,500
44,500
62,500
80,000
85,000
8O,OOO
Totals
71,643
88,125
83,309
120,655
157,598
169,713
I47,OOO
- Official figures. 1919 figures estimated.
Artificial Abrasives Carborundum and Corundum. The man- ufacture of carborundum or silicon carbide (SiC) in the electric furnace did not undergo any particular change during the period 1910-20, although the industry had developed considerably.
The electrometallurgical manufacture of artificial corundum, i.e. impure fused alumina, is new, however, and has become one of great importance in Canada.
Bauxite and coke are smelted in an arc furnace, the proportions used being as follows: Calcined bauxite 1,750 parts; coke 100 parts; iron borings 350 parts. The furnaces used for the manufacture are mounted on water-cooled tracks, and when one is full it is removed on the rails, and another is inserted in its place under the electrodes. The furnace body is merely a rectangular iron frame lined with fire-brick, with a hearth made from pitch and carbon. The furnaces operate at 100 volts and 5,500 amperes; about 18,000 K.W.-hrs. being required to produce an ingot of 4 to 5 tons in weight. The reduction must not be carried too far, otherwise the product will be too brittle; the presence of I to 2 % of iron, silicon, and titanium oxides, as impurities, improves the toughness of the abrasive. Brockbank gives this typical analysis of a high-grade artificial co- rundum : Al,Oj 97-40%; SiO ? -90%; Fe 2 O 3 -32% Tid 1-38%. The manufacture of artificial abrasives is confined chiefly to North America. In the year 1918, Canada alone produced 70,000 tons of these materials; while the value of the total exports of the
nited States was 1,000,000. Now that the limitations of silicon
and refining company was employing four i-ton and four J-ton furnaces, while another firm had four i-ton furnaces, and batteries of two or three furnaces were quite common.
The following types of furnace were stated to be in successful use:
1. The direct arc furnace, of which the Snyder is the only repre- sentative.
2. The indirect arc furnace, of which the Rennerfelt and the Detroit are the most successful examples.
3. The vertical ring induction furnace, of which the Ajax-Wyatt is the best known and most successful.
4. The granular resistance furnace, of which the Baily is the only example.
For rolling-mills using yellow brass, the direct and indirect arc furnaces are quite unsuitable, since they would lead to high zinc losses. Likewise the induction type of furnace is unsuited for foundries where alloys high in lead are made, or where frequent changes in composition are necessary. The type of furnace to be installed, therefore, is determined largely by the alloy or metal which is to be produced, and each works will have to be guided by expert and skilled advice in the selection of the type of furnace best suited to its needs and requirements. The question of power-costs also enters into the matter, and where cheap power is available the granular resistance type may be chosen in preference to the more efficient arc type of furnace, because of the savings which follow from the absence of electrodes. Bronze manufacturers who take
