USRE12424E - Process of reducing ores - Google Patents

Description

No. 12,424. REISSUED DEC. 12, 1905.

I H. BROWN.

PROCESS OF REDUCING 0113s.

APPLIUATION FILED SEPT.29,.1906.

" velops an exceedingly high local temperature,

process for such o'res wherein the constituents are freed of a reducing heat to the action ofgwhich the ore is subjected, the term from forty-to eighty feet in Twyers are introduced immediately below this 30.

establishing what is termed a force and velocity.

To all jwhom it may cOncern: Be it known that IfHoRACE F. BROWN, a citizen of the United States, formerly residbut now residing at Chicago, county of Cook, and State of Illinois. have invented certain new and useful Improvements in Processes of Reducing Ores; and I do hereby declare the following to be a full, clear, and

exact description of the same.

The present invention relates to an improved the reduction of metallic ores or through the agency reduction as herein employed being used in its general sense as meamng the complete the treatment thereof prior to the delivery of the ore acted upon to a collecting means for the finalact of separation.

. Ordinarily in the treatment of ore in what is known as a stack or blast furnace charges of ore, fluxes, and fuel, usually in the form of charcoal or coke, arealternately fed forming a column from eight to sixteen feet in copper and lead smelting practice and iron smelting.

column of charges and a blast of air forced in, the pressure required being governed somewhat by the height of the column and the nature of the material, usually from eight to sixteen ounces and as high as forty-eight ounces. This excessive blast-pressure defusing zone, extending upward from the twyers a probable average of two feet. Owing to the obstruction of the materials composing the charge, the blast and products of combustion do not pass uniformly upward through the mass, but seek channels through which they rush with great To a degree the whole charge is affected by the reducing properties of the heated gases that pass upward, and in proportion as all the'elements of the. charge are thus affected the process of reduction is facilitated. The burning of the coke has a threefold effect on the process-first, that of supplying heat forfusion; second, furnishing the required carbon for a reducing agent;

5 third, displacement, which leaves the charge more or less porous as the coke is consumed.

ing atOakland, county of Alameda, State of California,

separation of the constituents of the ore o'r.

\ usual practice the excess ally umn as the heat increases.

UNITED sTA'rFs PATENT CFFICF. HORACE F. BROWN, oF CHICAGO, ILLINOIS. v PBOOES$ OF nzoucme ones.

I I Specification of Beiuued Letters Patent. Beiasued Dec. 12, 1905. Original No. 774,930, November 15, 1.904:- Lpplloetion for teillae filed September 29, 1906. Serial No. 280,713.

In what is technically known as mattesmelting there is no reducing action, but simply a concentration, the sulfur in the charge combining with the iron and copper, forming a copper-iron matte, which collects all the values of gold and, silver. The excess of iron combines with the silica, lime, and alumina, &c., forming a slag which carries with it all the non-metallic impurities. the matte is predetermined by the amount of available sulfur in the charge. In lead-smelting and in the smelting of copper oxids the reducing action of CO (carbon monoxid) gas serves to deoxidize the previously-oxidized metals, reducing them to the metallic state, the silicates, &c., going 011' in the slags. Some of the sulfur is eliminated in the blast-furnace, especially where la hot blast is used, which raises the grade of the matte; but in the of sulfur is burned off previous to charging thefurnace;

In iron-smelting the oxidized ores are subjected to the reducing action of CO and gradudeoxidized in the slowly-descending col- The heightof the column is sufiicient to give time for complete reduction before the zone of fusion is reached. The time required depends largely upon the condition of the ore, and as it is necessary to charge the ore in coarse pieces agreat height of stack is required.

The theory and practice of ore reduction by smelting are based upon the combining or fluxing action of the different ingredients of the charge. Materials that of themselves are almost infusible and, 'at best, under a destructive heat are readily fused at acomparatively low temperature when combined with the proper fiuxing elements. In ore reduction by smelting the chief element found in the gangue-roek is silica, practically an infusible material, with of an oxid or sulfid. Molten silica (SlOz) will combine with iron in the form of ferrous oxid (F603) in practically equal amounts, and so great is their afiinity that this combination takes place practically to the exclusion of all metals..- Should there be an excess of iron in the charge, so there is an excess of iron in the slags, what is called a scouring-slag is the result, and so violent is the action of this excess of iron that it attacks the silicions ma- The grade of more or less iron in the form 20 a preliminary roasting 35 the load that must 4 of hydrocarbon fuel, as oil 60 they pass beyond the zone of the takes place under all conditions, and only by the oxidation of the sulfur can other than an IQ iron sulfid, orwhat is known as iron matte,

be produced. This matte has the property of combining with all of the metal contents of the charge, having an unlimited capacity for taking up gold, silver, and copper, the pro- I portionate value being governed entirely'by the amount of sulfur. Consequently the first step in the concentration of the valuable metals by smelting is to eliminatethe excess of sulfur. Hitherto this has been largely done by low fusion.

The disadvantages resulting from the foregoing treatment and which the hereinafterdescribed process seeks to obviate, so as to reduce the cost of reduction, are: (a) the losses in flue-dust, owing to the unavoidable amount of fines already in the ore and the decrepitation of the various ingredients of the charge under heat; (6) the loss of metallic gases forced 3 out too rapidly to be acted upon by the carbon monoxid and which, even if acted upon, are carried out by the powerful ascending blast; (a) the tendency of the charge to become compact, owing to the great weight of be sustained, the uneven distribution of the through the charge, and the imperfect reduction resulting from such causes. To, over- ,come these difficulties and to permit the use or gas, or of powdered charcoal, coke, or coal-dust, as well as to utilize the heat generated in the'rapid oxidation of sulfur and to conserve all possible units of heat, I have invented a simple and effective method or process for the complete reduction of the ore.

The essential feature of my improved process for desulfurizing the ore consists, first, in

passing the ore in a finely-divided condition 5 through a highly-heated non-whirlingatmosphere. The necessary fluxes, it will be understood, are added previous to charging the ore. This non whirling downwardly moving atmosphere permits of the passage of the finelydivided particles in a state of suspension and segregation, so that every particle of the ore is acted upon individually'by the said highlyheated non-whirling atmosphere. The second step resides in subjecting the particles as oxidizing atmosphere to the action of a whirling-reduction atmosphere which conveys the ore downward through a reducing zone of the stack within which the ore is being treated. This 5 atmosphere is so regulated that as it' passes e the travel of the under a heat much be-' heat and reducing-gases down the stack of the furnace a vortex isformed which brings the segregated particles together, which vortex also forms and maintains a zone of concentrated heat, so that instant combination and fusion takes place.

To successfully accomplish this desired end,

it is necessary to prevent a diffusion of heat by expansion of the gases, which requires that the furnace-shaft be of practically uniform size from end to end, or, preferably,

slightly contracted toward its bottom. The

whirling action of the reducing zone gathers together the particles of ore received therein 7 in asegregated condition and prolongs their travel through the furnace-stack, resultingin complete fusion within the stack or during particles through the zone of reduction.

In carrying out the improved process for the reduction of ores the ores and fluxes are crushed to a finely-divided state to the end that a morerapid chemical action may be gained during the travel or the ores through the zone of reduction.

Any suitable form of a stack-furnace may be employed in connection with "the working of the process hereinafter described, one style of furnace capable of successful use, if properly modified'in construction, being fully set forth-and, described in Letters Patent of the -United States No. 689,062, issued to myself on. the 17th day of December, 19-01. However, a simpler form of furnace capable of use for various ores is set forth in the annexed drawings, wherein Figure 1 is a vertical cross-sectional view taken through the furnace-shaft, feed means, for the ore, and through the hopper or storage-chamber into which the crushed or pulverized ore is fed, said view being on line mm, Fig. 3 of the drawings, viewed in thedirec tion of the arrow. Fig. 2 is a longitudinal sectional view disclosing the same features in .section as are set forth in Fig. 1 of the drawings. also the collecting-basin or hearth for the reduced ores, the exhaust-stack, connections whereby the utilized heat may be directed into the hopper or storage-chamber for the ore for the purpose of dehydrating the ore previous to its being 'fed into the reducingblast, also disclosing the manner of arranging the furnace where the same is to be utilized in connection with use for the recovery of quicksilver or for use in connection with the manufacture of sulfuric acid; and Fig. 3 is a cross-sectional plan view taken on linew' m, Fig. 2 of the drawings, said viewdisclosing the arrangement of the hyd rocarbon-bu rners.

In the drawings the' numeral 1 is used to indicate a vertical furnace-shaft, the upper end portion of which is formed into or has attached theretoa combustion-chamber 2. A suitable distance above the combustion-chamber is arranged a vibratory feed-plate 3, which is actuated by the eccentric 4 by means of the ore-hopper 9 by opening the damper 15.

,of ore within the hopper The ore or material is thus completely connecting-rod 5. Any suitable means may be employed for operating the eccentric 4- as, for instance, a drive-belt 6, working over belt-wheel 7, attached to the shaft 8, carrying the eccentric 4. The vibratory feed-plate 3. controls the outlet opening or spout 8 of the ore-receiving hopper or storage-chamber 9, which is'arranged immediately above the said feed-plate 3. Preferably within this hop'p'er 9 is located a series of staggered angles orlaterally-projecting partition-plates 10, so that The ore or material to be treated is introduced into this hopper by any suitable means in a finely crushedpr pulverized condition.

Below and connected with the shaft 1 is 10-? cated the collecting-chamber or hearth 11, which receives the treated material delivered from the shaft 1. From this hearth or colstack 12 for the waste products of combustion from the shaft 1. Connection is made between the stack 12 and the hopper 9 by means of the lines 13 14, the former being controlled by a damper 15'. Where the material to .be treated requires to be dehydrated prior to being delivered into the shaft 1, the waste products of combustion are permitted to enter {he 1e hot products of combustion will then circulate throughout the openings formed in the body by the staggered angles or plates, the heated gases absorbing all moisture of the finely-pulverized .ore very rapidly and finally escaping backinto the exhaust-stack through. the connecting-fins t114. e drated, so that it is charged to the furnace at a heat to cause the immediate ignition of all sulfur and to permit of reduction to begin at once.

The reducing-fuel utilized withinthe combustion-chamber for the production of a strong reducing atmosphere is oil or other carbonaceous fuel ejected into the combustion-chamber 2 in excess of the 'free oxygen, thus developing 'an excess of superheated carbon monoxid and active hydrocarbon gases which gives to the shaft 9. strong reducing'atm'osphere, which acts to fuse thematerial as carried through the zone of reduction. The relength of the shaft 1, although if necessary to produce a more strongly reducing atmosphere or zone than that obtained from the carbonaceous gases of oilfuel finely-powdered coke or charcoal can be fed in with the ore or be blown in at any desired point. The amount of this solid carbon thus admitted will be governed by the need. of such form of carbon for reduction. The draft of the furnace is such that a downdraft is given to the shaft 1, so

that the travel of the reducing-blast isin. a downward direction or from the combustionchamber toward the hearth or collecting .tent being the reverse of the ore is held spaced within the said hopper.

I gases to hang slightly,

lecting-chamber extends vertically the outlet condition and in suspension is deliveredablemeans for collecting or ducing zone extends approximately the entire means for the reduced material, to ,this exthe ordinary blastfurnace.

To insurea more complete combustion and. a more perfectand somewhat longer contact of the ore and heat the burners 16 for the oil fuel are so arranged within the combustionchamber that the flame is given a-spiral or rotating motion which will follow down the shaft, making a longer travel or path of travel for the falling ore. The gentle friction of the walls of the stack will cause the which willtend to forma vortex down the center of the stack through which the falling material will pass, keeping free of the outer walls. This will prevent accretion,

falling ore' from being cooled.

The ore is'fed by the vibratory feeder into the combustion-chamber through a highlyheateddownwardly-moving non-whirling at- I mosphere in a finely pulverized or crushed to the reducing-flame,and thus carried downward with the movement of the blast through the reducing zone, which, as before stated, is hpand also being a non-comv ducting medium the gases will prevent the proximately the entire length of'the said shaft.

Where .ore is being treated for the recovery of quicksilver, the furnace-shaft is formed with an inclined bottom 17, which deflects the waste material into any suitable collecting device. The fumes are carried off from the shaft through an outlet-pipe 18, which exhaust-pipe leads to or connects with any suitfor recovering the quicksilver from the fumes.'

In case the process is employed for treating ore for the manufacture of sulfuric acid a damper 18' in the exhaust-stack is closed and the fumes exhausted through the outlet-pipe 19 andtreated thereafter in the usual manner.

Whatever style of furnace construction be utilized theprocess of reduction by passing the finely crushed or pulverized ore through a shaftin contact with and in the same line of travel as the travel of the hydrocarbon or reducing blast is the same. The described process is a continuous one in contradistinction to the independent-charge system hereinbefore employed.

The zone of reduction within thefurnaceshaft may properly be defined as existing between the pointed 6, Figs. 1 and 2 of the drawings. While the zone of reduction is described as existing between the points ab, it must be understood that the atmosphere maintained between the vibratory feed-plate 3 and the combustion-chamber 2 is the highlyheated downwardly-moving non-whirling atmosphere to the action of which the ore is IIO first subjected during its travel through the stack; In the present case no distinction is made between an oxidiz ng and a reducing March 20, 1894; but in such furnace the ore atmosphere, inasmuch as the term atmospheric suspension, to

reduction is employed to cover such action as takes place'between the points a b, or what has been designated as the reduction-zone.

I am well aware of the fact that heretofore the roasting and smelting of ore has been accomplished by passing pulverized ore through a stack in contact with adownwardly-moving body of heat, suchas described in Letters Patent No. 516,662, granted to J; J. Storer is not first subjected to the action of an approximately non whirling highly heated downwardly-moving atmosphere and thence conveyed through a whirling body of downwardly-traveling reducing atmosphere which collects the segregated particles of ore by cre atinga vortex. The devices set forth in earlier Letters Patent, N 0. 41,250, granted to Whelpley et al. January 12, 1864, and No. 103,006, granted Arey May 17, 1870, are also known to me; but neither of these devices discloses my method of treating the ore.

Having thus described'my invention, what is claimed as new, and desired to be protected by Letters Patent, is-

1. The process of treating finely-divided ore, which consists in subjecting it, while in a preliminaryheating atmosphere, then to the action of a re ore into approximate ducing, fusing-flame and at the same time gradually bringing the particles of ore into approximate physical contact.

2. The process of treating finely-divided ore, which consists in subjecting it, while in atmospheric suspension, to a preliminaryheating atmosphere, and then to a heating and reducing flame in the form of an inverted cone, for the purpose of bringing the particles of physical contact.

3. The process of treating finely-divided ore, which consists in subjecting it, while in atmospheric suspension, to an oxidizing at- .rnosphere and then to a reducing fusing-flame,

at the same time gradually bringing the particles into approximate physical contact.

4. The process of reducing ores as a continuous operation which consists infirst passing the ore condition through a non-whirling atmosphere, and then subjecting the highly-heated ore to the action of a whirling heated atmosphere moving in the same direction as the travel of the falling body of ore.

h In witness whereof I have hereunto set my and.

HORACE F. BROWN. Witnesses:

J. H. LANDES, A. U. Thomas.

in a finely crushed or pulverized

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