US1295719A - Apparatus for treating ores preparatory to magnetic separation. - Google Patents

Description

R. w. ERWIN APPARATUS FOR TREATING ORES PREPARATORY T0 MAGNETIC SEPARATION.

APPLICATIQN FILED JAN-5.1914.

Patented Feb. 25, 1919.

2 SHEETSSHEEI' 1.

IIIIIIIIIIII IIIIIWWIIIII ZWM - R. W. ERWIN.

APPARATUS FOR TREATING OR ES PREPARATORY T0 MAGNETIC SEPARATION.

- APPLICATION FILED IAN)! I914. 1,295,719.- A Patented Fqb.25,1919.

' 2 SHEETSSHEEI 2.

fi y 7 ROBERT W. Enwm, or WAUKON,.IOWA, AssIoNoa, BY MESNE ASSIGNMENTS, 'ro

MISSISSIPPI VALLEY mow COMPANY, or WILMINGTON, DELAWARE, A Conro- RATION OF DELAWARE.

APPARATUS FOR TREATING ORES 'PREPARATOBY TQ .MAGNETIC SEPARATION.

Specification of Letters Patent.

Patented Feb. 25, 1919.

Application flledJanuary 5, 1914. Serial No. 810,532.

To all whom it may concern:

Be it known that I, ROBERT W. ERW N, a citizen of the United States, and residing at Waukon, county of Allamakee, State of Iowa, have invented certain new and useful Improvements in Apparatus for Treating Ores Preparatory to Magnetlc Separation,

of which the following is aspecification.

This invention relates to apparatus for clearing ore of its gangue, and more particularly to a process for clearing ores containing clay as a gangue.

Some ores, such as brown hematite and certain ores of copper, contain a large percentage of clay and sometimes silica as a gangue. These ores exist as nodules and boulders of various sizes in the clay beds, and the clay and silica, such as flint, stone, gravel and sand, are often found inside of the lumps or boulders. Now this gangue must be separated from the ore before it can be used economically in a blast furnace.-

In U. S. Patents Nos. 957,157, granted May 3, 1910 and 961,121, granted June 14, 1910 are described a process for clearing such clayey ore of its gangue. The process as de scribed in said patents may be briefly summed up as follows: The ore and its gangue are heated at a temperature and for. a period sufficient to render the gangue brit; tie and easily separable from the ore. The ore and its gangue are tumbled to shake loose the gangue from the ore, and the ore and gangue are subjected to a strong air blast so as to sweep, clean and remove the gangue from the ore.

While the air cleaning process of said pat.- ents produces a merchantable ore well suited for a blast furnace, and while this air cleaning process will free the ore of all of its clay gangue, it will not separate the rock, flint, gravel and sand from the ore to a sufficient extent. As stated above, this silica occurs in combination with clay as a gangue, and often occurs inside of the lumps or boulders of ore.

One of the objects of this invention there fore is to providean apparatus for clearing ore of its gangue, and more particularly to separate the silicious gangue therefrom.

Certain ores, such as limonite or brown hematite, and also red'hematite are non-magboiler iron netic. I have however discovered that these ores may be rendered magnetic, or magnetized by .a suitable magnetizing treatment.

Another object therefore is to develop a novel apparatus for magnetizing and magnetically concentrating ores, and more particularly iron ores containing gangue, and containing also free and combined moisture.

Further objects will appear from the detail description, and in describing the process reference will be had to the accompanying drawingsshowing one form of apparatus for carrying out the rocess. In these drawings,

Flgure 1 is a plan of an apparatus for carrying out the process embodying this invention,

Fig. 2 is a profile or side elevation, partly in section, of this apparatus,

Fig. 3 is a detail end elevation, showing the outlet door,

gig. 4 is a detailend elevation of the inlet en Fig. 5 .is a section on the line 5-5 Fig. 4,

Fig. 6 is an enlarged detail section on the line 55 Fig. 4, and

Fig. 7 is an enlarged detail section on the line 7-7 Fig. 5. V

Referring to the accompanying drawings, 71 designates a sizing trommel which screens or sizes the ore as hereinafter described.

The undersize from the trommel 71 is discharged into a hopper 76 and into a magnet izing converter comprising a cylinder 77 of provided with rings 78 resting on rolls 79 on pillars 80, and having a center thrust ring 81 cooperating with thrust rolls 8 2. This cylinder is rovlded with a toothed ring 83 meshing a suitable motor. The cylinder for about one-half of its length from its upper end is reduced as shown at 85 so as to form a comparatively long outlet of small diameter. Thus in a practical case, the cylinder is 60 feet long, has a large diameter ofifi feet and a small diameter of 3% feet.

The upper end of the cylinder makes an .airtight connection with an end plate'86 with a pinion 84 driven by' hopper 76 discharges'throug'h double valve casings 91 and 92, and a chute 93 extending through the late 76, into the cylinder 77. The valve casings 91 and 92 are provided with valves 94 and 95 respectively suspended by links 98 from levers 97 pivoted on the hopper casings. These levers are pivoted in the valve casings by sleeves 99 making close fits with hearing lugs 100 of the valve casings so as to make these joints airtight. The levers 97 are provided with weights 101. Links 102 are pivoted at their lower ends to the arms 97 and are provided at their upper endswith elongated slots engaging cranks 103' on a shaft 104, which is driven from any suitable source of power.

, A pipe 105 rojects into the cylinder and extends just through the bottom wall of the chute 93. This pipe 105 receives crude oil under a pressure of about 150 lbs. per square inch from a tank (not shown.)

The lower end of the cylinder 77 is closed by a door 107 pivoted at its upper end to the frame 108 and held closed by strong springs 109. The door 107 has a cut out portion 110 in which is pivoted a small door 111 closed by weaker springs 112. Both doors bear against the end of the cylinder so as to form an airtight joint, but the lower door 111 is opened by the material passing out of the cylinder, the opening being however only sufiicient to permit the ore to'pass out. The function of the double door is that of a Safety device, for if an explosion takes place both doors will blow open and therefore furnish a large outlet for the exploded gases and thereby prevent damage to the converter.

A conveyer 115 takes the material from the second converter to a sizing trommel 116 which sizes. the material to a seriesof sizes so that it can be conveniently operated upon by magnetic separators. The material on the conveyer 115 is passed underneath sprays 114 of cold water to quench the same. The material from the sizing trommel is con'-. veyed to magnetic separators indicated at 11 These magnetic separators separate the ore from the gangue, the ore being con- -veyed to a suitable ore bin and the tailings discarded.

The operation will now be described, and in this operation we will take as a practical case, for the material operated upon, limonite or brownv hematite containing a large percentage of clayas a angue, contaimng also siliceous gangue suc as stone, quartz gravel and sand, and containing both free and combined moisture.

The preliminary operations performed on the ore prior to the magnetization proper is generally stated as follows: The ore as mined is first subjected in a converter, which we will call the first converter to a drying heat which drives oil the free'moisture and renders both the ore and gangue friable so The crushed ore and gangue is.

the converters it will not only be entirely freed from its clay gangue, but also from practically all of its free and combined moisture, so that the ore will be in a dry and porous condition, brought about by the 'cleaning out of the gangue and the expulsion of the combined moisture Furthermore the cracking of the ore lumps and the tumbling will free the silicious gangue from the ore, so that while this silicious gangue may not all be separated from theore by the air blast, it will be loosened therefrom to enable it to be separated in the subsequent operation hereinafter to be described. The converter or converters for performing the preliminary operations so far described are fully shown and described in applications, Serial Numbers 810,530 and 810,531, filed of even date herewith by Edward F. Goltra, Thomas S. Maflitt, Jesse D. Dana, and Robert W. Erwin, to which reference is had for details of construction and operation. The ore as it leaves the converter or converters in which the above operations are performed? is at a cherry red heat, or at about 1300" The ore and gangue as discharged fromthe second converter is sized in the sizing trommel 71 to two sizes, an undersize of one-half inch and less, and an oversize of r,

one-half inch and over. This sizing takes place for two reasons. First, it is found that the oversize does not contain very much silicious gangue, and-can therefore be conveniently and economically hand-picked, sec ond, it is found that the subsequent magnetizing process and the subsequent magnetic separation can be performed more effectively if performed on an undersize of one-half inch and less, although I have found that the magnetizing and magnetic separation can be performed on pieces which will pass through a one inch mesh.

, The undersize from the sizing trommel 71 is passed directly to the magnetizing converter. This converter is made as air-tight as possible to prevent the entrance of outside air. The material is fed by the double valve, which excludes outside air, since these valves are so operated that one will be always closed while the other is open. En-

trance of air during the feeding of the ore is therefore prevented. A gaseous hydrothe hot ore. This construction will also cause the ore sliding down over the end of the pipe to keep the outlet clean and free. The oil forced into the converter cylinder will volatilize and form a dense and-concentrated hydrocarbon atmosphere in the cylinder. The upper end of the cylinder is of large diameter so as to furnish a large volume for the hydrocarbon gases to act on the material. The lower end of the cylinder, or rather the lower half, is reducedin.

diameter so as to form a small outlet, thereby preventing entrance of air. The swinging doors at the lower end of the converter cylinder will also keep out the air, and the large door is normally held closed while the lower or small door only opens to let out the material. The material as discharged into the magnetizing converter is at 1000 F. or over. inthe third converter at about 1000 F. and over 900-F, as it has been found that the temperature in this converter must be over 900 F. in order that the desired action may take place. The material is kept in the converter for thirty minutes or over. It has been'found when treated as described, the ore as it leaves the converter is magnetic. The material as it leaves the converter is taken by a conveyer to.a sizing trommel 116, and while being conveyed is subjected to the action of jets of water to cool the same. The material is sized to meet the varying requirements of magnetic separation and is then separated magnetically. The material "can be separated at as high a temperature as the magnetic separators will take it, but it will be found that it can be separated cold.

The ore as it comes from the mine is limonite or brown hematite, that is, hydrated sesquioxid of iron, 2Fe,O ,3H O. The ore as it leaves the first preliminary operations has all its free and combined moisture extracted and is porous. The ore is at this time in fact red hematite, or Fe O and contains no moisture, either free or combined. This condition is brought about by the successive drying, crushing and calcining. 'The action of the hydrocarbon gases on the ore in the magnetizing converter, at the high temperature-there maintained, results in a reduction of the sesquioxid to the ferrosoferric oxid, or from Fe O to Fe,O or

Fe-,O,, FeO, and possibly lower oxids such as the protoxid or monox-id of iron, that is, FeO. The action, may however be in part a physical change, and the magnetization may be in part due to a physical change.

The material is therefore maintained The magnetizing process embodies five salient features which distinguish it from prior processes, and which render it commercially available.

First. The ore is sub-divided to an extent suflicient to permit the reducing gas to penetrate lnto the piece of ore, so as to reduce practically the entire mass thereof to Fe O, and possibly lower oxids. In the prior methods no particular attention was paid to this matter of sub-division. As a result the ore was not reduced to an extent suflicient to permit its separation by the magnetic separators. It seems there was formed only a or surface efi'ect and any combined moisture left in the ore probably had an effect of oxidizing the reduced layer of Fe .,O,and FeO back to Fe O It will be noted that in the prior processes the ore if reduced in size at all was reduced or crushed after it left the reducing kiln. The result was therefore, thatapart from any oxidizing action taking place after the ore left the kiln, in the crushing, the interior of the lumps vwould be left non-magnetized and would not, of course, separate out in the magnetic separator. This is probably what caused the inefiicient magnetic separation of the ores as magnetized by the prior processes.

Second. It seems that the critical temperature at which the reducing action takes place is about 900 F. In accordance with this method the temperature is carried to over 900 F., and is usually about 1000 F. It has been found that when the temperature is dropped below 900 the reducing action is very ineflicient, gives no permanent magnetization, and is commercially a practically no hydrogen. Thus in the processes of the pr1or art where blast furnace gases, producer gases and coke were used in a kiln, these gases contained practically no hydrogen and the reducing action of these gases was therefore not sufficient for this ore. It will also be noted that in the processes of the prior art the gases were necessarily dilute and contained large quantities of nitro en. Now in order to obtain an efficient reducing action the gases must be rich and concentrated. This is the case with the present process where ahydrocarbon is used, which is rich in both carbon and hydrogen. Hydrogen is one of the strongest reducing agents which can be employed. Now the splitting of the hydrocarbons results in hydrogen being set free, and that this takes place is in this process evidenced by the carcontaining no Oxygen,

bon coating on the ore as it leaves the magnetizing converter.

Fourth. In the processes of the prior art the gases necessarily contained considerable free oxygen. Now in the reducingof the ore it is necessary to maintain an atmosphere and it has been found that unless the air is kept out the reducing action is not only ineflicient but fails. Air not only causes oxidation but dilutes the gas. In the present process the air is carefully excluded so that no oxidation or dilution of the hydrocarbon gases can take place.

Fifth. In accordance with this process both the free and combined moisture are driven ofi? prior to subjecting the ore to the action of the magnetizing reagent. If.

the moisture, and more especiall the combined moisture is not driven 01% then the magnetization will not alone be incomplete, but will not be permanent, since a reoxidation may take place due to the presence of this combined moisture, as pointed out above. ,Moreover the porosity of the ore not only permits a better penetration of the gases, but also results in a more permanent I magnetizing action.

While we have advanced an explanation and theory to explain the action taking one,

place,'we do not however desire to be understood as advancing this theory as the only or as being .necessary, but merely one which may be advanced from the results actually obtained by practical mercial operation of the process.

It is obvious that various changes may be made'in details of construction without departing from the spirit of this invention, and it is, therefore, to be understood that this invention is not to be limited to the specific construction shown and described.

Having thus described the invention what is claimed is:

1. An apparatus for treating ores preparatory to magnetic separation, comprising a converter having an inlet and an outlet and adapted to receive and permit passage of theore and its associated gangue therethrough, means for feeding the ore and gangue to said converter, means for maintaining'a magnetizing reagent in said converter adapted to render the ore magnetic, and means for sealing the inlet and the outlet of said converter against entrance of air, adapted to permit free passage of the ore and gangue to and from the same.

2. An apparatus for treating ores preparatory to magnetic separation, comprising a converter having an inlet and an outlet and adaptedto receive and permit passage of the ore and its associated gangue therethrough, means for maintaining a magnetiz ing reagent in said converter, and means for feeding the ore and gangue through said inlet and into said converter, constructand, comed and arranged to prevent entrance of air I ing reagent in said converter, and a double feeding valve for feeding the ore and gangue through said inlet and into said converter, constructed and arranged to prevent entrance of air through said inlet into said converter while the ore and gangue pass into said converter.

4. An apparatus for treating ores preparatory to magnetic separation, comprising a converter having an inlet and an outlet and adapted to receive and permit passage 'of the ore and its associated gangue therethrough, means for feeding the ore and gangue through said inlet and into said converter, and means for feeding a magnetizing reagent to said converter at the point of entrance of the ore and gangue.

5. An apparatus for treating ores preparatory to magnetic separation, comprising a converter having an inletand an outlet and adapted to receive and permit passage of the ore and its associated gangue therethrough, means for feeding the ore and gangue through said inlet and into said converter, means for maintaining a. magnetizing reagent insaid converter, adapted to render the ore magnetic, means for sealing the inlet of said converter against entrance of air to said converter, and a safety door for said outlet, adapted to seal said outlet against entrance of air to said converter.

6. In an apparatus for treating ores preparatory to magnetic separation, an inclined drum having an inlet and adapted to'permit the ore and its associated gangue to pass therethrough, means for 1'0? tating said drum, means'for maintaining an atmosphere in said drum adapted to render the ore magnetic, and means for sealing the inlet and outlet of said' drum against entrance of air while the ore and gangue pass into and from said drum.

7. In an apparatus for treating ores preparatory to magnetic separation, an inclined drum having an inlet and an outlet and adapted to permit the ore to pass therethrough, means for rotating said drum,

means for maintaining an atmosphere in an outlet and clined drum having an inlet and an outlot and adapted to permit the ore .to pass therethrough, means for rotating said drum, means for maintaining an atmosphere in said drum adapted to render the ore magnetic, and ore feeding means adapt ed to seal said drum while the ore and gangue pass into said drum.

9. In an apparatus for treating ores preparatory to magnetic separation, an inclined drum having an inlet and an outlet and adapted to permit the ore to pass therethrough, means for rotating said drum, means for maintaining an atmosphere in said drum adapted to render the ore magnetic, and a double acting ore feeding valve adapted to seal said drum while the ore and gangue pass. into said drum.

10. In an apparatus for treating ores v preparatory to magnetic separation, an inclined drum having an inlet and an outlet and adapted to permit the ore to pass there-' 12. In an'apparatus torv treating ores preparatory to magnetic s eparation,an inclined drum having an inlet and an outlet and adapted to permit the ore to pass,

- therethrough, means for rotating said drum,

and -means for discharging a reagent on the entermg ore, whereby the reagent will beeome vaporized by-contact with the ore and create in said drum an atmosphere adapted to render the ore magnetic 13. In an apparatus for treating ores preparatory to magnetic separation, an inclined drum having an inlet and an-outlet and adapted to permit the ore to pass therethrough, means for rotating said drum, and a reagent pipe having its outlet in the path of the entering ore,,whereby the reagent will become vaporized by contact with the ore and create in said drum an atmosphere adapted to render theore magnetic.

In an apparatus for treating ores preparatory to magnetic separation, an inclined drum having an inlet and an out let and adapted to permit the ore to pass therethrough, means for rotating said drum, means for feeding ore into said drum, and means for. discharging a reagent under the bank of ore passing said feeding means to render the ore magnetic.

15. In an apparatus for treating ores preparatory to magnetie separation, an inclined drum having an inlet and an outlet and adapted to permit theore to pass therethrough, means for rotating said drum,

and means for admitting a reagent to said drum adapted to discharge the same on the ore to become vaporized thereby so as to create insaid drum-an atmosphere adapted to render the ore magnetic, and ore inlet and outlet closures for said drum adapted to seal the drum against entrance of air.

In testimony whereof I a my signature in the presence of two witnesses.

ROBERT w, ERwrN. Witnesses:

' HARRY ORR,

FRANK GAMJPBEEL.

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