US784651A - Method of smelting ore. - Google Patents

Description

PATENTED MAR. 14, 1905.

R. BAGGALBY.

METHOD OF SMELTING ORE.

APPLICATION FILED APR. 8, 1904.

3 SHEETS-SHEET 1.

1 5 T L? U n n m n n n n1 WITNESSES PATENTED MAR. 14. 1905 R. BAGGALEY. METHOD OF SMELTING ORE.

APPLICATION FILED APR. 8, 1904.

3 SHEETSSHEET 2.

PATENTED MAR. 14, 1905.

R. BAGGALEY.

METHOD OF SMELTING ORE.

APPLICATION FILED APR. 8, 1904.

3 SHEETS-SHEET 3.

eoooco oeooo WITNESSES Patented March 14, 1905.

PATENT OFFICE.

RALPH BAGGALEY, OF PITTSBURG, PENNSYLVANIA.

METHOD OF SMELTING ORE.

SPECIFICATION forming part of Letters Patent No. 784,651, dated March 14, 1905. Application filed April 8; 1904. Serial No. 202,195.

To all whom it may concern.-

Be it known that I, RALPH BAGGALEY, of Pittsburg, county of Allegheny, and State of Pennsylvania, have invented a Method of Smelting Ore, of which the following is a description, reference being bad to the accompanying drawings, in which Figure 1 is a side elevation, partly in section, of a furnace suitable for the practice of my invention. Fig. 2 is a vertical cross-section on the line II II of Fig. 1. Fig. 3 is a detail view of the twyer connection. Fig. 4 is a longitudinal section of one-half of a furnace of modified construction. Fig. 5 is an elevation thereof. Figs. 6 and 7 are detail views of a part, showing modified constructions.

My invention provides means for the continuous smelting of sulfid and other ores of copper without need of previous water-concentration and calcination and with the use of no carbonaceous fuel or a very small proportion of such fuel.

I use in my process from two to three times the volume of air-blast utilized in prior practice. This entails a greater expense; but it is fullyjustified, because I am able through this means to eliminate (a) the enormous investments and expenses incident to the water concentration process; (1)) the twenty-percent. or even greater losses in mineral values inseparably attached to water concentration; (0) the investments, expenses, and losses con nected with calcining; (d) the flue-dust and volatilization losses due to slow smelting as heretofore practiced; (e) the costs of handling and railroad freights in transporting ore as heretofore to points where an abundant water-supply for concentration is available. In short, the practice heretofore used involves the production of a fifty-per-cent. matte by means of water concentration, calcination,and slow smelting, while my process consists in quickly smelting the entire ore tonnage, eliminating the worthless portion of it, comprising about nine-tenths of the tonnage in the form of slag, through fusion alone, and enriching the remainder by means of converting-twyers to any degree that may be desired within certain limits.

Former practice represents enrichment by water concentration, calcination, and slow smelting, with heavy expenses and mineral losses of at least thirty per cent, while my process represents concentration through the medium of intense heats, with very small mineral losses, with only a fraction of the expenses for most purposes, and with only a slight increase of investment and expense, due to the large volume of converting-blast which I employ.

The losses inseparably connected with the practice heretofore followed in the Butte district computed from the raw ores in the charging-bin to blister-copper generally average thirty-five per cent. of all the mineral values contained in the ores, and they even exceed this percentage. In the best practice these losses have not fallen below thirty per cent. in the portion of the treatment that covers alone the transforming of ore into blister-copper.

The art of producing copper as practiced heretofore has comprised the following processes:

First. The process used by the Spaniards in Mexico and in the southern portions of the United States and in Central and South America, which consisted simply in repeated smeltings and roastings in primitive furnaces until the impurities had in this laborious manner been ultimately eliminated.

Second. The various methods of roasting,

smelting, and leeching as practiced at Rio Tinto, Spain, since the time of the Roman Empire.

Third. The Mabuki process as practiced in Japan since ancient times and which con sists in smelting and roasting in primitive furnaces and thereafter in bessemerizing the matte in extremely crude apparatus.

Fourth. The art as practiced at Swansea, WVales,'for certainly two centuries past and at Stora Kopparberg, in Sweden, for a shorter period, which consists in repeated roastings and repeated smelting in small reverberatory furnaces, the oxidizing action of the air-current in its flight through the furnace to the stack being slightly aided by flapping or splashing the molten bath with a hand-tool. Finally the bath was refined by green-wood poles submerged in the bath, whereby the heat of the latter was utilized to produce hydrocarbon reducing-gases.

Fifth. The art as practiced at Mansfield, in Germany which consists in repeated roastin gs and repeated smeltings, the latter being done in small circular cupolas or furnaces, usually supplied with a single smelting-twyer, but sometimes equipped with two such twyers.

Sixth. The art as practiced in New Jersey, which consists of the use of large brick furnaces both for oxidizing and for reducing, the treatment itself being similar to that practiced at Swansea, Wales.

Seventh. The art as practiced at a Butte reduction works, which consists in stall-roasting, smelting in a common blast-furnace to produce the converteranatte, and thereafter treating this matte in large furnaces.

Eighth. The art as practiced at Jerome, Arizona, which consists in heap-roasting about half of the ore tonnage of the mines in the open air for four months and a half and thereafter smelting the roasted ores in the proportion of half and half with the richer ores produced from the same mines in order to produce converter-matte, thereafter the treatment of this matte in bessemer converters in the usual manner, and thereafter the treatment of the blister-copper by the poling process in large brick tilting furnaces.

Ninth. The art as practiced at Bisbee, Arizona, which consists of the use in the furnace charge of carbonate and oxid ores exclusively, excepting only a minute proportion of sullids that have unavoidably been mined while removing the carbonates and oxids. These sullids are thoroughly calcined in rotary roasters and are then added to the charge. The ores are smelted in small oval cu polasa modification of the little German cupola in use at Manslield, Germany--and are then bessemerized. The subsequent treatment of the blister-copper is in the ordinary brick refiningfurnace with reducing-gases supplied by the poling process.

Tenth. The art as practiced near Greenwood, British Columbia, which consists in smelting a favorable low-grade self-fluxing ore in ordinary water-jacketed blast-furnaces with about ten per cent. of high-grade coke and thereafter treating the matte in ordinary converters up to blister-copper.

Eleventh. The art as practiced at Luster, near Durango. Mexico, in which a favorable sulfid ore is smelted in a small special waterjacketed blast-furnace with a consumption of seven or eight per cent. of coke, producing a fifty to sixty per cent. matte, in which form the product is sold. The low percentage of coke used is due to the peculiarity of the ore and to the use of a heated blast provided through the use of wood found in the neighborhood.

Twelfth. The art as practiced at Mount Lyell, Tasmania, which consists in smelting favorable sulfid ores in blast-furnaces with a large valume of blast and with from three to four per cent. of carbonaceous fuel as a means of producing the converter-matte, thereafter treating this matte in converters in the usual manner, and thereafter treating the blister-copper in refining-furnaces by the poling process.

Thirteenth. The art as practiced at Douglas, Arizona, in which the ore charge consists exclusively of carbonates and oxids which simply require fusion with coke in order to transform them into rich converter-mattes.

Fourteenth. The art as at present practiced at Ducktown, Tennessee, which consists in smelting a low-grade pyrrhotite ore in large water-jacketed furnaces supplied with blast by a blowing-engine that delivered into the furnace twenty-two thousand and eighty cubic feet of air per minute. The low-grade matte so produced was resmelted when mixed with rich converter-slag and with six per cent. of

coke, and the resultant matte was then treated in a bessemer converter.

Many attempts, with great outlay of money, have been made to successfully smelt and convert ordinary copper ores without water concentration and calining directly to blister-copper or to converter-matte; but none of these efforts have ever been put into successful commercial operation, although the advantages of so doing are of the greatest importance.

The accompanying drawings show apparatus well adapted to the practice of my invention.

2 is a furnace which is constituted of a material which is indestructible by the high temperature and corrosive slag and matte produced in my process and which will not conduct the heat so rapidly from the charge as to chill it and interrupt the metallurgical operation. For this purpose I prefer to construct it of thick slabs or blocks of metal, such as copper or cast-iron, which may have passages formed near their outer faces for the circulation of cooling streams of water, air under pressure, or simple air circulation.

3 is the slag-outlet.

4 is the matte-outlet.

6 6 are the smelting-twyers, which enter the furnace somewhat above the level of the slagoverflow.

The furnace has charging-openings 7 and a stack 8. Converting-twyers 9 9 are shown near the furnace-bottom, and the matte taphole, with its safety-bot, is shown in Fig. 1. The slag-overflow and its cover may be adjusted as shown in Figs. i and 5.

At their outer ends the twyers have heads 10, formed with openings 11 for the insertion of a bar and blast-plugs, the openings being normally closed with ball-valves 11. The con verting-twyers are provided with cardboardbottom gaskets, Fig. 3, so that should matte escape from any cause it will burn the cardboard and flow onto the ground in a stream until the twyer has been plugged instead of solidifying in the twyer-box.

As a means of regulating and controlling the volume of blast delivered into the bath I use bars =12, Fig. 6, preferably made of iron, which I insert into any or all of the twyers at which I wish to shut off the blast. The bars are made large enough in diameter to practically shut off the twyers and prevent the blast from entering the furnace. For instance, if the twyer be one inch in diameter I may use a round bar seven-eighths or even three-quarters inch in diameter. The length of the bar is such that when the shoulder 13 engages or strikes against the wind-box on the outside of the twyer the bar will reach within an inch or half-inch of the point at the inside limit of the twyer-orifice where the blast enters the matte. By inserting such bar into the twyer-hole the blast will be shut off from this one twyer and a small quantity of matte will chill against the bar at the inside end of the orifice. This small quantity of chilled mattesay one-half inch or one inch in thicknesswill at once make an airtight joint for the blast, a non-conducting protecting-layer for the end of the bar, and a seal against the escape of matte. The shoulder 1?) on this bar is preferably made square, so that it may be turned with a wrench and so that the joint with the matte plug may thus be ruptured and the bar removed. The matte seal or plug may then be removed whenever it is desired to reopen the twyer by using the ordinary punching-bar.

If desired, the shoulder on the bar may be set one or two inches farther back, and a loop of the same width may be used inside the shoulder when the bar is inserted into the twyer. This loop (shown in Fig. 7) will admit of the bar being inserted into the twyer only the exact distance required, so that its end shall be one-half or one inch distant from the end of the twyer-hole. When it is desired to reopen the twyer, this bar. can be driven in with a hammer as a means of rupturing the seal and for the removal of the bar from the twyer. I have found in practice, however, that the simplest and best method of closing a twyer is to use a short bar as first described having a square shoulder, so that it can be turned with a wrench and thus removed, and of the exact length that when the shoulder presses against the outside of the twyer the end of the bar will reach to within one-half inch of the inside of the twyer-orifice. In practice I insert this bar for a few moments or long enough to enable it to chill the inside matte seal, and I then turn it with a wrench by engaging the square shoulder, and I then remove the bar from the twyer entirely, depending thenceforth on the matte seal alone for closure of the twyer, which I have found by experience it is perfectly safe to do. I can throw this closed twyer again into action by using an ordinary punching-bar,supplemented, if necessary, with a hammer. By using these bars I can close all the smelting and converting twyers without injury to the furnace or to its subsequent working, and I can thus reduce the volume of blast at will. I can also quickly close the lower twyers when it is desired to shut off the blast preliminary to tapping the slag or matte.

In the practice of my invention after having heated the furnace by burning wood, gas, or oil I supply it with a molten matte rich in oXidiZable fuel-making constituents, such as sulfur, iron, &c. This matte is made by smelting suliid ores@'. 0., ores high in mattemaking elements and relatively low in silica. The matte thus provided constitutes the molten bath with which my invention is practiced. It may be melted in the furnace itself or it may be supplied from an outside source. The latter is better, because when the charge is melted in the furnace with coke some of the coke will always remain unconsumed and becoming enveloped in molten slag or matte will remain as an infusible obstruction on the furnace-bottom, or if eventually loosened by the action of the converting-twyers it will float in an infusible state on the surface of the matte. The furnace having thus been charged with a layer B of molten matte, which fills the crucible or hearth up to the level of the slag tap or overflow and safely covers and thus protects the converting-twyers from slag, the operator then charges into the furnace a body 0 of ore, together with a small percentage of cokesay about three per cent. of the latter. This is introduced and maintained in such limited volume that it will float in the bath B well above the bottom of the furnace. Thus in Fig. 1 I show the ore body as extending down to the level D. It is essential that the weight of the body of ore thus introduced should be restricted in this manner, because if it should be introduced in a mass of considerable size, as in processes heretofore attempted, its weight will force it down within the body of molten matte until its base engages the bottom of the furnace. This so obstructs and fills the hearth or crucible as to interfere with the operation of the converting-twyers, and it causes slag to form at the level of these twyers, and as these are relied upon to supply the air which combines with the oxidizable elements of the matte and develops the necessary heat the obstruction of the furnace by the chilled slag and ore would prevent successful operation and by causing the furnace to chill after tapping off the matte would bring the process to a stop. This will be understood and appreciated by those skilled in the art, for it is well known that when the blast is delivered into pure matte it produces intense heats, while when it plays into slag,

, upper and lower rows of twyers.

particularly When it is mixed with ore, it exerts a chilling effect.

Blasts of air are introduced through the The air from the upper row of twyers acts upon the body of coke and ore and smelts it, while the blast of air from the lower row of convertingtwyers being thus forced to play into pure matte alone by combining with and oxidizing the combustible elements of the bath-such as sulfur, iron, &c.--generates in the bath a very high temperature. The heated bath acting upon the submerged portions of the ore dissolves the metallic sulfids therefrom, while the silica flux, combining with the oxidized iron of the bath, forms slag, which floats in a layer E and is drawn off through the slag tap or overflow. The operation of the furnace is thus continuous, the bath of matte being enriched by the blast and dissolving the ore which floats in it, the matte produced by smelting of the body of ore above descending and becoming incorporated with that below.

The ore which is charged is selected with reference to the condition of the matte and the temperature of the furnace. A portion of sulfid ore rich in matte-making elements, such as the ordinary pyrrhotite ore, is introduced in order to supply the bath with fuel compo-- nents, and charges of highly-silicious ore are introduced to serve as a flux for the oxidized iron and to yield values to the bath. These charges, with perhaps other fluxes, such as lime, when necessary, are fed to the bath alternately and in quantities as required; but they must not be fed in such quantities as to force the ore and coke down to the bottom of the furnace or even near to the level of the converting-twyers.

As the bath of matte B accumulates portions are withdrawn for further treatment,

care being taken to leave suflicient of it in the furnace to cover the converting-twyers to an ample depth.

Care must also be taken that the matte-bath shall not become too highly enrichedthat is to say, its contents of sulfur, iron, and other fuel values should not become lessened to such an extent as to endanger the operation of the furnace by causing it to chill. For these reasons the matte in the bath should never be allowed to exceed sixty per cent. in values, and it should preferably not exceed forty per cent. Its condition in this regard can be regulated quickly and readily by changing the character of the ore introduced into the furnace. Thus if the matte should become too highly enriched sulfid ore containing relatively large the volume of blast introduced at the twyers the operator is enabled to maintain perfect control over the working of the furnace.

I have learned that without the floating body to serve as a cover for the bath it is impossible to carry on a successful smelting process in this manner for any length of time with open furnaces, such as that shown in thedrawings and such as have heretofore been used by all experimenters heretofore in this field, all of whom have been unsuccessful because of the fact, among other things, that slag and matte are continuously splashed up against the side and end walls of the furnace and, becoming chilled by the water-jackets, constantly accumulate on these walls above the bath until they finally choke the furnace by scaffolding, and thus quickly bring the process to a full stop. As a result of this experience I have designed a special furnace to meet and to correct these troubles, which forms the subject-matter of United States application, Serial No. 202,391, filed April 9, 190A. In my present invention it will be noted that I use an open furnace with side and end walls that hold and conserve the internal heat instead of constantly extracting and dissipating it, as thin water-jackets must do, and I eflfectually prevent all splashing and all possibility of accretions on the furnace-walls by constantly maintaining a floating charge of ore and coke deep enough to prevent such splashing.

In the modification of my invention shown in Figs. 4t and 5 I illustrate an adjustable slag-tap designed to permit the slag-opening to be enlarged when the slag is thick and viscous and when it needs to be raked or rabbled out of the furnace. In this case I provide above and below the slag-tap verticallysliding water-cooled pieces 14 14:, the adjacent ends of which form the limits of the slag-tap hole and one of which carries a slagspout 14. These are moved vertically by a powerful mechanismto wit, by racks 15 and. pinions 16and by thus moving the lower spout-piece and its upper cover in opposite directions the slag-opening can be enlarged and ready access afforded for a rabbling-tool, with which any sticky slag may be removed. By lowering the spout the flow of the slag may be accelerated. By using water-jacketed pieces in this portion of the furnace I prevent the inner skull or slag lining from forming a bond with the inside of the jacket, and I am thus enabled to move these pieces by means of the powerful mechanism, as stated.

Within the scope of my invention as defined in the claims the steps of the process may be modified in many ways, since WVhat I claim is 1. The method herein described of producing matte which consists in forming a molten bath of matte, and charging a body of ore in such limited quantity that it will float with its bottom above the bottom of the furnace, and blowing air into the bath; substantially as described.

2. The method herein described of producing matte which consists in forming a molten bath consisting of matte, charging a body of ore in such limited quantity that it will float with its bottom above the level of the converting-twyers, and blowing air into the bath and into the body of ore above the bath; substantially as described.

3. The method herein described of producing matte, which consists in forming a molten bath of matte, charging a body of ore in such limited quantity that it will float with its bottom above the bottom' of the furnace, and blowing air into the bath, and renewing the floating body of ore from time to time; substantially as described.

4. The method herein described of producing matte which consists in forming a molten bath of matte, charging a body of ore in such limited quantity that it will float with its bottom above the bottom of the furnace, and blowing air into the bath, withdrawing the slag above the level of the bath, and blowing air into the ore body above the level of the slag-outlet; substantially as described.

5. The method herein described which consists in blowing a converting-blast into a body of molten matte and maintaining a floating body of unfused charge material to retain heat in-the bath and prevent splashing of slag or matte from the action of the convertingtwyers; substantially as described.

In testimony whereof I have hereunto set my hand.

RALPH BAGGALEY.

iV-itnesses:

J. H. REED, THOMAS V. BAKEWELL.

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