US1259467A - Smelting copper and like ores. - Google Patents

Description

T. W. CAVERS.

SMELUNG COPPER AND LIKE ORES.

APPLICATION FILED JUNE 29. 1917..

1 ,259,6?. v Patentad Mar. 12, 1918.

THOMAS WILLARD CAVERS, 0F COPPERHILL, TENNESSEE.

SMELTING COPPER AND LIKE ORES.

Specification of Letters latent.

- Patented Mar. 12, 1918.

Application filed June 29, 1917. Serial No. 177,738.

To all whom it may concern:

Be it known that I, THOMAS CAVERS, a subject of the King of Great Britain, residing at Gopperhill, in the county of Polk and State of Tennessee, have invented certain new and useful Improvements in Smelting Copper and like Ores, of which the following is a specification. I

The present invention has for its object to produce economies in the smelting of copper-containing sulfid ore, or sulfid ore containing other matte-forming metals, which operation is ordinarily carried out in a water jacketed blast furnace.

In the ordinary process, ore, such as copper-bearing pyrites, together with a flux such as limestone and silicious matter is introduced into the upper part of the blast furnace, together with more or less coke. In the ordinary methods of operating, the amount of coke necessary will-depend to a considerable extent upon the character of the ore and other conditions, and in practice a minimum quantity of coke, relative to the burden in the furnace is employed. The ore employed is itself fuel, that is to say during the operation, the sulfid ore is oxidized by the blast, some of the sulfur being usually driven off in the free state, and most of the iron sulfid being burned to form sulfur dioxid and iron dioxid, which latter combines with the silica present to form an iron silicate slag. In ordinary practice, however, the heat furnished by the combustion of the ore itself is not suficient to make up for the large loss of heat in the outgoing matte and slag and outgoing hot gases, and the considerable quantity of heat carried away by the water in the water jackets forming the sidesof the furnace. It is accordingly-necessa in ordinary practice to introduce some ad itional fuel with the charge, this heretofore beingentirely introduced at the top of the furnace. y

In other kinds of metallurgical operations it has been proposed to blast in fuel. This has, been proposed in connection with numerous reducing processes in which iron oxid ore, or oxidized iron ore, is mixed with reducing agent and flux, and heated under reducin conditions for the purpose of producing iron metal.

According to the present invention I introduce, with the blast in the lower part of the furnace, a short distance above the normal slag level therein, fine coal, or other WILLARD carbonaceous fuel. It is not necessary to previously coke the coal, but the coal may be and preferably is employed in its origi- Iral condition, usually in the form of relatlvely finely divided mass, for example the cheap soft coal, although if the coal is in large pieces it should be crushed so that the largest pieces of coal present will be not larger than say one-third of an inch. Large pieces obviously would produce clogging or would choke up the pipes.

In addition to coal I may add in this manner, other copper-bearing material, besides that introduced at the upper part of the furnace, copper concentrates, cop per-bearing flue dust, rich copper ores (which may or may not be sulfids) and in some cases I may also employ fluxing agents.

For maximum eiiiciency in the operation of my process, (especially after the furnace is in operation) no coke should be introduced at the top of the furnace, all of the extraneous fuel being introduced with the smelting blast through twyers. At' times, however, particularly during the operation of blowing in the furnace, it may be found advantageous to introduce more or less coke at the top of the furnace. In some instances it is possible to employ other kinds of carbonaceous fuel, oil in some instances and this likewise may be being suitable,

flue dust mixed with copper concentrates, and the like.

In the ordinary operation of a blast furnace of the type herein referred to, where coke is introduced with the charge, the coke takes fire a considerable distance above the focus, and a considerable amount of the heating value of the coke is generated some distance above the point where the heat is needed, and all the heat so generated is substantially lost, only a small fractionthereof being absorbed by the charge and carried down into the focus. In accordance with my invention, extraneous fuel being introduced at near the bottom of the furnace with the blast, the extraneous fuel is all burned in the lower part of the fu1'nace, and by generating the heat close to' the twyers, the actual focus of the furnace is lowered. The burden in the upper part of the furnace remains relatively cool, no material quantity of heat being generated above the focus, and the gases accordingly leave the upper part of the furnace at a much lower temperature than inordinary practice.

mon practice of introducing the coke at the top of the furnace, whereas with the same furnaces, and with the same ores, I have found by actual tests that it is possible to get along with as little as 4%, Without in any manner introducing other difliculties into the operation. In addition to the saving in amount of fuel, there is a much greater saving in the character of the ,fuel,

' since coal of the character employed costs only about half as much per ton as coke.

In addition'to the smelting of sulfid ores containing copper, the invention is also applicable to the smelting of sulfid ores containing other matte-forming metals, such as nickel and the ores also may of course contain precious metals in addition to the copper, nickel or the like.

In the accompanying drawing, forming a part of the present specification, I; have illustrated apparatus suitable for use in carrying out the process of my present invention, the view being a vertical elevation, parts being shown in section.

In said drawing, 1 represents a blast furnace of the water-jacketed type, 2 the sole plate, 3 suitable supports, and 4 one of the twyers, of which there may be any suitable number. The dotted line 5 represents the normal slag level. 6 is the bustle pipe and 7 the twyer pipe, in which the blast is regulated by the gate or valve 8. Into some point in the air passage, and preferably be tween the twyer box 4 and the gate 8, is connected a fuel supply pipe 9 leading from a hopper-bottomed receptacle or bin 10 for introducing the coal, with or without the other materials above referred to. In the bottom of this receptacle or bin, I place a screw conveyer, the end of which enters the upper end of pipe 9 as shown at 11, which is suitably revolved, as by gear 12. The screw will keep the upper and horizontal end of the pipe 9 filled with coal, which will prevent air from blowing out through the bin 10. v

In operation, coal, e. g. fine soft coal, coal slack, or in some instances coke breeze, etc.,

'which may be crushed, although this is not necessary, so long as it contains 11% lumps large enough to clog the pipes, to which may be added the materials above referred to, is

fed by the screw 11, into pipe 9, the end'of the screw and the fine material in the convolutions thereof within the pipe 9 forming an air seal, then the said material flows downwardly through the sloping part of pipe 9, into the twyer pipe 7, where it is rapidly carried by the blast into the furnace, where the coal, etc., is practically all burned in the focus of the furnace, thereby furnishing heat at the part of the furnace where the intense heat is needed, 2'. 6. within the slag-forming zone or nucleus.

In the reduction of iron ores in the blast furnace, it has heretofore been proposed to In the above description, I have described the invention as applied to semi-pyritic smelting, but the invention is also applicable 1n the smeltlng of roasted ores, such roasted ores containing copper or nickel or both, as-

sociated with iron oxids and other metal oxids, and always associated with a considerable percentage of sulfur. The smelting operation, with roasted ores is dependent upon the presence of an excess of sulfur over the amount that would be required to unite with all the copper or nickel present, since the object of the smelting is the production of a matte containing copper sulfid or nickel sulfid or both, mixed with varying amounts of iron sulfid.

The roasted ore to be smelted, assuming that the same may contain about 6% of copper, or copper and nickel, may contain about say 10% of sulfur, and a portion of this sulfur is oxidized during the smelting operation- There is of course always a suflicient amount of sulfur present to produce a matte the lower part of the furnace, through the twyers. The amount of coal employed in,

smelting oxidized ores according to the presenkinvention will be necessarily much larger than the amount employed in semipyritic smelting, since substantially the en-- tire amount of heat generated in the furnace has to come from the coal employed. The amount of coal employed, however, in smelting roasted'ores in accordance with the present invention is materially less than the amount of coke which would be employed in smelting oxidized ores of the same char acter, where the coke was introduced at the top of the furnace with the charge.

In smelting oxidized ores according to the present invention, I am able to secure substantially the same advantages, as in the case of the semi-pyritic smelting above referred to, namely I localize the zone of high heating lower down in the furnace, I considerably" reduce the amount of fuel necessary, I am able toemploy low grade fuel, that is to say cheap fuel in the form of.soft coal and the like, and if desired I can also introduce other materials, such as those above referred to, with the blast, and

as in the case of semi-pyritic smelting, the

exit gases from the furnace are at a lower temperature than those produced in introducing the extraneous fuel with the charge.

While fuel has been blasted into a blast furnace, in the production of metallic iron, by reduction of oxid ores, I call attention to the fact that in, such process, the operation depends upon the maintenance of reducing conditions in the lower portion of the blast furnace, or cupola, whereas in smelting, either pyritic or roasted ore smelting, reducing conditions in the bottom of the furnace must not exist, since there would be liability to produce sowsof metallic iron.

What I claim is:

1. A process of smelting copper-bearing sulfid ores, which comprises the step of blowing into the lower part of the blast furnace at a point somewhat above the slag level, a blast of air carrying a small amount of a carbonaceous fuel, said amount of fuel being only a small fraction of the amount of fuel capable of being burned by the volume of air so introduced.

2. A process of smelting in a blast furnace, metal sulfids which contain iron sulfid and sulfids of other matte-producing metals, without introducing solid carbonaceous fuel with the charge at the furnace top, said process comprising the step of introducing with the blast, a relatively small amount of finely divided solid carbonaceous fuel to furnish a part of the heat'in the focus of the furnace, whereby said solid fuel so introduced is all .burned in the lower part of the fur- I at the top of the furnace, by introducing with the blast a relatively small amount of extraneous carbonaceous fuel and material containing matte-forming metal, into the lower part of the blast furnace charge at a point above the normal slag level, whereby at least the major part of said extraneous fuel is burned in theslag forming nucleus, and the matte-producing material is smelted.

5. A process of smelting metal sulfid materials containing iron sulfid and the sulfid of another matte-forming metal, which comprises the step or blowing into the lower part of the furnace charge, above the slag level and at a level adjacent the slag-forming zone, a blast of air, carrying a small amount of carbonaceous fuel, said amount of fuel being only a small fraction of the amount of fuel capable of being burned by the volume of air so'introduced.

In testimony whereof I affix my signature.

THOMAS WILLARD OAVERS.

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