(_a_) The use of a material which is not perfectly suited for
constructional work, hence repairs occupy longer time.
(_b_) The risks of destroying the lining mechanically near
the tuyeres, owing to the extra punching required at
these points.
(_c_) The operation and manipulations requiring extreme care and
attention, owing to the tendency for the production of very
high temperature during the great evolution of heat in the
early stages of the blow, when large quantities of iron are
being oxidised.
(_d_) The tendency to losses, by the blowing out of the dry
siliceous ore, when first turning on the blast.
=Converter Shop Organisation.=—The introduction of the basic lining
has, to a large extent, overcome the necessity for devoting so much
shop space to the repair department, which formerly occupied a very
considerable area. The converter stands are usually placed in alignment
down one side of the building, the centre space is kept clear, and is
commanded by the travelling crane for the conveyance of the ladles
of matte, metal, or slag, to or from the converters. At Anaconda,
the converters are charged from a train of matte-ladles mounted on
bogies which run along a track behind the converters and situated some
distance above them, the matte being poured down a launder which swings
into position over the converter throat.
At Copperhill, Tenn., the converters are charged from ladles which are
filled from the blast-furnace settlers situated at the other side of
the furnace-building, whilst at the most modern large plant, at Tooele,
Utah, the matte is run directly from the reverberatory furnaces to the
converters along launders which are nearly 80 feet long and inclined at
about 7 in 100. This method avoids all the handling of matte by cranes
and ladles with the attendant troubles of skulls, breaks-down, spills,
etc., and no difficulty has been found in keeping the channel free and
open, nor in supplying matte at a sufficiently high temperature. At
Anaconda and Tooele, the side of the converter-shop situated opposite
to the converters is devoted to the refining and casting furnaces and
to the slag-casting machines.
=Modifications of Converter Practice.=—(1) _David’s Best Selecting
Process._—David devised a special form of converter and suggested
a method for conducting in the converter, instead of in the
reverberatory furnace, the operations of the best “selecting process”
on the principles of the old Welsh practice. The method embodied the
converting of the matte somewhat beyond the white metal stage, by
which means a small quantity of metallic copper was produced, in which
the whole of the gold and silver values and most of the impurities
collected, the remaining white metal being left tolerably pure. The
metallic copper, thus obtained, was run into a side pocket in the
lining and tapped from there, the rest of the pure white-metal was
blown up to pure best-select copper.
[Illustration: Fig. 68.—General View of Converter Shop, Anaconda.]
The method is, however, too specialised for ordinary commercial copper
smelting, especially when electrolytic refining of the crude metal can
be conveniently arranged for.
(2) _The Haas Converter._—The Haas converter is spherical in form,
and the tuyere holes through the lining are arranged at such an angle
as to lessen the pressure required for the forcing of air through the
metal. It is claimed for this form that it ensures better mixing of the
materials and more even wear on the lining, by imparting a swirling
motion to the bath.
References.
Douglas, James, “Treatment of Copper Matte in the Bessemer
Converter.”
_Trans. Inst. Min. and Met._, 1899, vol. viii., p. 1.
Baggaley, “A Brief Description of the Baggaley Process.”
Heywood, W. A., “The Baggaley Pyritic Conversion Process.”
_Eng. and Min. Journ._, 1906, Mar. 24, p. 576.
Knudsen, E., “Pyrite Smelting by the Knudsen Method in Norway.”
_Mineral Industry_, vol. xviii.
Moore, Redick R., “Copper Converters with Basic Linings.”
_Eng. and Min. Journ._, 1910, June 25, p. 1317.
Editorial, “Improvements in Copper Smelting.”
_Eng. and Min. Journ._, 1911, Mar. 4, p. 450.
Schreyer, Fr., “The Question of the Basic Bessemerising of
Copper Mattes.”
_Metallurgie_, 1909, vol. v., No. 6, p. 190.
“Improvements at the Washoe Smelter.”
_Mines and Minerals_, 1910, April, vol. xxx.,
No. 9, p. 520.
Vail, R. H., “The Pierce and Smith Converter.”
_Eng. and Min. Journ._, 1910, Mar. 12., p. 563.
Moore, Redick R., “Basic-lined Converter for Leady Copper Mattes.”
_Eng. and Min. Journ._, 1910, Aug. 6, p. 263.
“Recent Practice in Copper Matte Converting.”
_Eng. and Min. Journ._, 1910, Sept. 3, p. 460.
Neal, Carr B., “Further Data on the Basic Converter.”
_Eng. and Min. Journ._, 1911, June 13, p. 964.
Keller, E., “A Study of the Elimination of Impurities
from Copper Mattes in the Reverberatory
and the Converter.”
_Mineral Industry_, 1900, vol. ix., p. 240.
Mathewson, E. P., “The Relative Elimination of Iron, Sulphur,
and Arsenic in Bessemerising Copper Mattes.”
_Bull. Amer. Inst. Min. Eng._, 1907, Jan. 7, No. 13, p. 7.
Offerhaus, C., “Operation of an Anaconda Converter.”
_Eng. and Min. Journ._, 1908, Oct. 17, p. 747.
Levy, D. M., “The Successive Stages in Bessemerising Copper
Matte as indicated by the Converter Flame.”
_Trans. Inst. Min. and Met._, 1910., vol. xx., p. 117.
Hixon, H., “Notes on Lead and Copper Converting.”
Semple, Clarence C., “Analyses of Converter Fume.”
_Eng. and Min. Journ._, 1911, Mar. 11, p. 508.
Haas, Herbert, “The Vortex Copper Converter.”
_Eng. and Min. Journ._, 1910, May 7, p. 972.