US1301684A - Process for clearing clayey ores. - Google Patents

Description

E. F. GOLTRA, T. S. MAFFIIT, J. D..DANA & R. W. ERWIN. PROCESS FOR CLEARING CLAYEY ORES.

APPLICATION FILED JAN. 5. I914. 1L.3@11.@4 Patented Apr. 22,1919.

4 SHEETS-SHEET I.

E. F. GOLTRA. T. S. MAFFITT, J. D. DANA & R. W. ERWIN.

PROCESS FOR CLEARING CLAYEY OHES. APPLICATION FILED JAN. 5. 1914. l mfimh Patented Apr. 22, 1919.

4 SHEETS-SHEET 2.

LSQLGSU E. F. GOLTRA T. S. IVI'AFFITT, J. 'D. DANA'& R. W. ERWIN. PROCESS FOR CLEARING CLAYEY ones.

Patented Apr. 22, 1919.

APPLICATION FILED JAN- 5. WM.

4 SHEETSSHEET 3.

E. F. GOLTRA, T. S. MAFFIIT, J. D. DANA & R. W. ERWIN, PROCESS FOR CLEARING CLAYEY OHES.

I APPLICATION FILED JANI5. I914. 1 m1 84k Patented Apr. 22, 1919.

4 SHEETSSHEET 4.

I I I I v onrrn snares rarnnar clarion.

I EDWARD I. G-OLTM THOMAS S. MAFFITT, D JESSE D. DANA, 015 ST. LOUIS, MISSOURI,

AND ROBERT W. ERWIN, 0F WAUKON, IOWA, ASSIGNDRS, BY MESNE ASSIGNMENTS, T0 MISSISSIPPI VALLEY IRON COMPANY, OF WILMINGTON, DELAWARE, A CORPO- RATION OF DELAWARE.

raocnss FOR CLEARING- CLAYEY onus.

Specificationjof Letters Patent.

Application field January 5, 1914i. Serial Ito. 810,530.

To all whom it may concern: 7

'Be it known that we, EDWARD F. GoL'rRA,

THoMAs S. MAFFITT, JESSE D. DANA, and ROBERT W. ERWIN, citizens of the United States, and residing at St. Louis, State of Missouri, and Waukon, Iowa, respectively, have invented new and useful Improvements in Processes for Clearing Clayey Ores, of which the following is a specification.

This invention relates to processes or methods 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 nodulesand boulders of various sizes in the clay beds, and the clay and silica, such as flint, stone.

gravel and sand, is often found inside of the lumps or bouldersf Now this gangue must be separated from the ore before it can be used economically in a blast furnace. 4

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 described 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 brittle 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 cleanin process of said patents produces a mere antable ore well suited for a blast furnace, and while this air cleaning process will free the ore of substantially 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 lnnips or boulders of ore.

One of the objects of this invention there fore is to refine the process described and claimed in the above patents so as to render it more etlicient, so as to clear the ore of all various ores having characteristics permitting its utilization, more particularly various ores containing clay as a gangue and occurrlng 1n the form of nodules in the clay, and containing considerable moisture both free and combined.

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

Figure 1 is a diagrammatical plan view of an apparatus illustrating the process embodying this invention,

Fig.2 is a profile or elevation also in diagrammatical form,

Fig. 3 is an enlarged diagrammatical detail profile or elevation,

Fig. 4 is another enlarged diagrammatical detai profile or elevation showing the second converter, I

Fig. 5 is a plan showing the third converter,

Fig. 6 is a profile or side elevation, partly in section, of this third converter,

Fig. 7 is a detail end elevation, showing the outlet door,

Fig. 8 is a. detail end elevation of the inlet end,

Fig. 9 is a section on the line 9 9 Fig. 8,

Fig. 10 is an enlarged detail section on the line 99 Fig. 8, and

Fig. 11 is an enlarged detail section on the line 11-11 Fig. 9.

The apparatus generally stated consists of three converters designated generally by A,

one-third ofits length from its lower end Patented Apr. 22, 1919 with fire brick or other suitable material, while the unlined part has a series of inwardly projecting shelves or lifters extending therealong. The upper end of the cylinder projects into a stationary hopper casing 16 connectin with a hopper 17, which hopper receives the ore from stationary grids 18 which in turn receive the ore from the mine. The grids are spaced any suitable distance so as to allow the ore below a certain size to pass therethrough; thus in this particular instance these grids are spaced from 12 to 14 inches.

inches apart so as to allow everything under 14 inches to pass into the hop-per 17. This hopper is provided with two hinged valve plates 20 and 21 placed in series to prevent the gases in the converter from entering the hopper. The casing 16 is connected with a stack 22 through a fan 23 driven by a motor 24. This fan will cause a draft from the lower to the upper end of the cylinder and up the stack 22. The lower end of the cylinder projects into a. casing 25 which is provided with rolls so as to be movable longitudinally of the cylinder along a track 26, to allow for expansion and contraction of the cylinder. A pulverized coal burner 27 receives the coal from a. bin 28 and an air blast from a fan or pump 29, and this coal is blown in a pulverized condition into the lower end of the cylinder 10. The cylinder is provided with a toothed ring 30 meshing with a pinion 31 driven by a suitable motor.

The ore is dicharged from the cylinder 10 on shaking or reciprocating grids 35, which in this particular case discharge everything below 2=} inches into a chute 36, while the oversize discharges into a crusher 37, which maybe of the gyratory type, and which crusher reduces the material to 2% The chute 36 from the reciprocaiting grids, and the. chute 38 from the crusher discharge into an elevator 39, which elevates the material and discharges it into a sizing screen or t rom'mel 40. This trommel sizes the material in this particular instance to three sizes. The fine material passes by achute 41 to a tailings bin 42, the second sized material passes by a. chute 43 to a belt conveyer 44, discharging into the ore bin 45 and the oversize or coarse material passes onto a picking belt 46 where it is hand-picked and the picked ore discharged onto t 1e conveyer 44 and hence taken to the ore bin 45'. The hopper 47 for the tailings bin 42 extends upwardly underneath the belt 46 so as to receive the flint, etc., picked from the belt. s

The material from the bin 45 is taken to the second converter B which is shown in detail and enlarged in Fig. 4. This second converter is of substantially the same construction as the first converter- A and is operated in substantially the same manner. It consists in this particular instance. of an inclined cylinder 50 about 125 feet long and 8 feet in diameter. It is however lined for a little over three-fourths of its length from its lower end with fire brick or the like, while the unlined part is provided with inwardly projecting shelves extending therealong. This cylinder is supported by rings 51 on rolls 52 and 520 on pillars 53 and 54. The center set of ring 51 and rolls 520 in this case also form a thrust bearing. The upper end of the cylinder extends into a casing 56 which is connected to an exhaust fan 57 discharging into a dust collector 58 and from there into a stack 69. This dust collector may be of any suitable. form and may be provided with inclined shelves 59 placed in staggered relation so as to separate the dust from the air before it is discharged into the stack. An outlet 60 is provided for this dust collector. A conveyer 61 conveys the ore from the bin 45 to the casing56 and hence to the cylinder 50, The lower end of'the cylinder projects into a casing 62 provided with rolls and adjustable lengthwise of the cylinder along a track 63. A pulverized coal burner 64 receives coal from a bin '65 and air from a blower or pump 66, and this burner blows the pulverized coal into the lower end of the cylinder. The cylinder is provided with a toothed ring 67 meshing with a pinion 68 driven by a suitable motor.

The material as it leaves the second converter is taken by an elevator 70 to a sizing trommel 71 which in this case sizes the ore to two sizes. The oversize is taken by a conveyer 72 and discharged onto a picking belt 73 where the flint etc. are hand-picked, while the picked ore is discharged into the bin 74. The ore on the conveyer 72 is subjected to a water spray 75 so as to cool down the material before it reaches the picking belt 73.

The undersize from the trommel 71 is discharged into a hopper. 76 and into the third converter C which will now be de-' scribed. Referring more particularly to Figs. 5 to 11 inclusive, which show the third converter in detail, 77 designates a cylinder of boiler iron provided with rings 78 resting on rolls 79 on pillars 80, and having a center thrust ring 81 coiiperating wit-bl thrust rolls 82. This cylinder is provided with a toothed ring 83 meshing with a pinion 84 driven by a suitable motor. The cylinder for about one-half of its length from its upper end is of a comparatively large diameter, while the lower 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 of 6% feet and a small diameter of 3%. feet.

The upper end of the cylinder makes an.

airtight connection with an end plate 35.?236

morass supported on a bracket 87, the end connection beingmade by a ring 88 on a reduced extension 89 of the cylinder pressed by springs 90 against the end plate 86. .The hopper 76 discharges through double valve casings 91 and 92, and a chute 93 extending through the plate 86, 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 withbearing lugs 100 of the" valve casings so as to make these joints air-tight. 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 ends with elongated slots engaging cranks 103 on a shaft 104, which is driven from any suitable source of power.

A pipe 105 projects into the cylinder and extends just'through the bottom wall of the chute 93. This pipe 105 delivers crude oil under a pressure of about 150 lbs. .per square inch from a tank 106.

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 the cylinder, the opening being however only sufidcient 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 conveyor 115 takes the material from the third converter to a sizing trommel 116.

which sizes the material to a series of sizes so that it pan 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 sizingtrommel is conveyed to magnetic'separators indicated at 117. These magnetic separators separate the ore from the gangue, the ore being conveyedto a suitable ore bin such as 74 and the tailings discarded.

The coal is stored in a bin 120 from whence it is conveyed to a drier 121. From the drier the coal is taken by conveyers 122 and 123 to bins 28 and respectively. in the diagrams, 124. designates the power house and 125 and 126 designate tracks.

The operation will now be described, and in this operation we will take as a practical case, for the material operated upon, limouite or brown hematite containing a large the converter is maintained at about 2200 F., while the stack temperature, or the temperature at the upper end of the converter,

is maintained at about the boiling point of Water. The exhaust fancreates a draft of about one-half ounce. A low pressure current of air is thus passed through the drum,

the air entering both with the pulverizedcoal and through the outlet passage in the casing 25. The material in passing through the first converter is subjected to a drying heat, and the operation performed in this first converter is therefore a drying operation, whereby the material is freed of substantially all of its free moisture. During 1ts passage through the converter the ore and gangue, including the heavy boulders, which are as large as 14 inches, are lifted and tumbled around, and during this tumbling operation the heavy boulders will break up to some extent and break and disintegrate the ore and gangue, so that a crushing operation is performed in this converter, Simultaneously the massot ore and gangue is subjected to a gradually increasing temperature, as the temperature increases from the upper to the lower end oi? the converter, and this ore and gangue will therefore be gradually dried out. This combined drying and tumbling operation will also render the ore friable, and will in addition separate, 1'. 6., shake loose some of the clay and other gangue, including the larger stone, mixed with the clay. lit will be noted however that while a draft of air is passed through the cylinder of this lirst converter, the blast is not a strong blast, for its function is merely a drying function; its function is not primarily to carr off any or" the gangue, although some of t 1e clay which has become free and very finely powdered will be incidentall I carried oh by the 7 draft. The ore as it is ischarged from the first converter is at about 250 F, and this from the rest by a trommel, as hereinafter described.

The ore and gangue as discharged from the first converter is passed over the shaking grids 35 which pass everything below 2%- inches into the elevator 39, while the oversize is sent to the crusher 37 and crushed down to 2J inches, and discharged into the elevator 39. and gangue to the sizing tronnnel 40 which sizes the material in three sizes as follows: one-sixteenth inch and below, one-sixteenth inch to three-fourths inch, and three-fourths inch and over. It is found that the one-sixteenth and below consists mostly of sand and clay and is very lean in ore. This size is therefore discharged directly into the tailings bin 42. The one-sixteenth to threefourths is discharged directly into the ore bin 4.5 by means of the conveyer belt 44. The three-fourths and over is discharged onto a picking 'belt 16 where the flint, etc., are hand-picked, the picked ore passing into the ore bin. The purpose of the sizing between the second and third sizes is to facilitate the hand picking, as it is found that most of the rock, flint and other siliceous material freed from the ore will be found in this size. This sizing of the ore therefore first, discards the fines, consisting mostly of sand and clay and containig very little ore, and second, throws onlythe larger sizes on the picking belt where the flint, .etc., may be readily hand-picked and discarded.

The material is taken from the ore bin 45 to the second converter B. This second converter is driven at such a speed, and the incline is such, that the material will pass through this converter in about 45 minutes. The flame temperature maintained at the lower end of this converter is about 3200 l while the temperature at the upper end is from 400 to 500 F. The exhaust fan in this case creates a strong blast through the converter cylinder of about 1-} ounces, which blast will lift particles of sand onesixteenth of an inch in diameter. As the material passes through the converter it is tumbled around, and at the same time subjected to the .hot strong blast passing through the converter. The temperature in this case also increases from the u per to the lower end of the converter cylin er, but

' this temperature is very much higher than in the first converter. As the ore passes along the converter cylinder it will be subjected to a calcining heat which not only drives off any free moisture which may be present, but also drives ofi the combined moisture. The high temperature causes the ore and any associated siliceous gangue to cxpand unequally and thus break open the lumps and expose this gangue. As the ore is thus tumbled around and subjected to the This elevator takes the ore reorcet heat, the gangue will be loosened by the heat and shaken loose by the tumbling action, and dried out so as to become very brittle, and this gangue is powdered by the tumbling action of the lumps against one another. This gangue so loosened and powdered will be picked up by the strong blast passing through the converter and carried along with it, while the ore will continue downwardly toward the discharge end. The gangue will not only be shaken loose from the surface of the ore, but will also be shaken out of the cracks and crevices in and around the ore, and this gangue will be separated from the ore by the strong blast. The blast will also seek out the gangue in the cracks and crevices and separate it from the ore lumps, so that when the ore reaches the discharge end of the converter it Will be freed of all of its clay gangue. It will therefore be seen that after the ore leaves the converter it will not only be entirely freed from its clay gangue, but also from 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 siliceous gangue from the ore, so that while this siliceous gangue may not all be separated from the ore by the air blast, it will be loosened therefrom to enable it to be separated in the subsequent operation hereinafter to be described. The ore as it leaves the second converteris at a cherry red heat, or at about 1300 F.

The ore as discharged from the second converter is sized in a sizing trommel to two sizes, an undersize of one-half inch and less,

and an oversize of one-half inch and over.v

therefore be conveniently and economically hand-picked, second, 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 we have found that the magnetizing and magnetic separation can be performed on pieces which will pass through a one inch mesh. The oversize is cooled down by sprays of water 75 and then discharged on a picking belt 73 where the ore is hand-picked.

The undersize from the sizing troinmel 71 is passed directly to the third converter C. This third converter is made as airtight as possible to prevent the entrance of outside air. The material is fed by the double valves, which exclude outside air, since these valves are so operated that one will be always closcd while the other is open. En-

converter B is at about 1300 F, and as disore. ore sliding down over the end of the ipe to aoaeea trance of air during the feeding of the ore is therefore prevented. A gaseous hydrocarbon atmosphere is maintained by feeding in crude oil under 150 lbs. pressure, and this oil is fed in directly under the ore bed as it slides down the chute into the converter cylinder, so as to mix directly with the hot This construction will also cause the keep the outlet clean and free. he 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 reduced in 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 it is discharged from the second charged into the third converter C is at 1000 F. or over. The material is therefore maintained in the 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 third converter C for 30 minutes or over. It has been found when treatedv as described, the ore as it leaves the conyerter is magnetic, a. e., it is attracted by a magnet. 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 varyin requirements of magnetic sep aration an 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,0,,3H,O. The ore as it leaves the first converter has all its free moisture extracted but will have very little if any of the combined moisture taken out. The combined moisture is taken out of the ore during its age through the successive drying, crushing and calcining. The action of the hydrocarbon gases on the ore in the third converter, at the high temperature there maintained, results in all probability, in a reduction of the sesquioxid to the ferroso-ferric oxid, or from Fe O to Fe,,0,, or lFe O Fe(), and possibly lower oxids such as the protoxid or monoxid of iron,.that is Fe(). The action, may however be in part a physical change, and the magnetization may be in part due to a phyiscal change.

The magnetizing process embodies five salient features which distinguish it from prior processes. and which render it oommercially available.

First. The ore is sub-divided to an extent suflicient to permit the reducing gas to penetrate into the piece of ore, so as to reduce practically the entire mass thereof to Fe O and possibly lower oxids. Tn 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 sutiicient to permit its separation by the mag netic separators. It seems there was formed only a film or surface effect and any combined moisture left in the ore probably had an effect of oxidizing the reduced layer of F 0,0, and FeO back to Fe,@,. 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, that apart from any oxidizing action taking place after the ore left the kiln. in the crushing, the interior of the lumps would be left. non-magnetized and would not. of course." separate out in the magnetic separator. This is probably what caused the ineflicient 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. lln accordance with this method the ten'iperature is carried to over 900 F., and is usually about 1000. It has been found that when the temperature is dropped below 900 the reducing action is very inefficient. gives no permanent mag netization. and is commercially a failure.

Third. In accordance with this method a hydrocarbon gas is used which is rich in carbon, and more particularly in hydro en. The reducing action of this gas is therefore more eiiicient than if a gas is used which is not so rich in carbon and contains no or practically no hydrogen. Thus in the processes of the prior art where blast furnace gases. producer gases and coke were used in a kiln, these gases contained practically no hydrogen and the reducin action of these gases was therefore not su cient for this ore. It will also be noted that in the proc esses of the prior art the gases were necessarily dilute and contained large quantities of nitrogen. 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 hydrocarbon 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 evidenced by the carbon coating on the ore as it leaves the third converter.

Fourth. In the processes of the prior art the gases necessarily contained considerable free oxygen. Now in the reducing of the ore it is necessary to maintain an atmosphere containing no oxygen, and it has been found that unless the air is kept-out the reducing action is not only inefficient 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 off prior to subjecting the ore to the action of the magnetizing reagent. If the moisture, and more especlally the combined moisture is not driven ofi', 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 magnetizing action.

While we have advanced an explanation and .theory to explain the action taking place, we do not however desire to be understood as advancing this theory as the only one, or as being which may be advanced from the results actually obtained by practical and commercial operation of the process.

Wh1le We have described only one particular apparatus for carrying out this process, it will be obvious that this method may be carried out by apparatus other than described. It will further be obvious that while this process is particularly suitable for clayey iron ores, this process, and more especially some of its features, may be utilized with other ores having. characteristics to permit the utilization of this process. It is therefore to be understood that this invention is not to be limited to the details shown and described.

The apparatus is fully described and claimed in our application, Serial Number 810,531, filed of even date herewith, while the magnetization process per 86 is fully dc scnbed and claimed 1n an application of necessary, but merely one RobertW. Erwin, Serial Number 810,532, filed of even date herewith.

Having thus described the invention what is claimed is:

1. The process of clearing ores having iron as an economic component, having clay as a gangue and containing both free and combined moisture, comprising, preliminarily heating the ore together with its iron component and its gangue to drive off the free moisture, tumbling the ore and gangue to break up the same, then subjecting the dried ore and gangue to a separate and com plete heating operation to drive off the combined moisture, tumbling the ore and its gangue to loosen the gangue from the ore, and subjecting the ore and its gangue to a blast which removes the gangue from the ore.

2. The process of clearing ores, having iron as an economic component, having'clay as a gangue and containing both free and combined moisture, comprising preliminarily heating the ore together With its iron component and gangue to drive 011' the free moisture, then subjecting the ore and gangue to a separate heating operation to drive ed the combined moisture, and separating the gangue from the ore.

- 3. The process of clearing ores having iron as an economic component, having clay as a gangue and containing both free and combined moisture, comprising, heating the ore' together with its iron component and gangue to drive off the free moisture, subecting the ore and gangue to a separate heating operation to drive 011' the volatile matter, tumbling the ore and gangue to loosen the gangue from the ore, and subject ing the ore and gan e to a blast which separates the gangue mm the ore.

4. The process of clearing ores, having iron as an economic component, having clay as a gangue and containing both free and combined moisture, comprising, preliminarily and gradually heating the ore together with its iron component and its gangue to drive ofi the freemoisture, subjecting the ore and its gangue'to a separating heating operation to drive oif the combined moisture, tumbling the ore and itsgangue to loosen the'gangue from the ore, and subjecting the ore and its gangue to a blast which removes the gangue from the ore.

5. The process of clearing ore, having iron as an economic component, of its gangue, comprising heating the ore together with its iron component and its gangue, crushing the resultant ore and gangue, tumbling the crushed ore and gangue to loosen thegangue from the ore, and subjecting the ore and its angue to a blast which removes the gangue rom the ore.

6. The process of clearing ore, having iron as an economic component, of its gangue,

comprising heating the ore together with its iron component and its gangue, crushing the resultant ore and gangue, heating and tumbling the crushed ore and gangue to loosen the gangue from the ore, and subjecting the ore and its gangue to a blast which removes the gangue from the ore.

7. The process of clearing ore, having iron as an economic component, of its gangue, comprising heating and tumbling the ore together With its iron component and its gangue, crushing the resultant ore and gangue, heating and tumbling the crushed ore and gangue to loosen the gangue from the ore, and subjecting the ore and its gangue to a blast which removes the gangue from the ore. i

8. The process of clearing ore, having iron as an economic component, of its gangue, comprising subjecting the ore together with its iron component and its gangue to a drying heat, crushing the resultant ore and gangue, then subjecting the crushed ore and gangue to a calcining heat, and separating the gangue from the ore.

9. The process of clearing ore, having iron as an economic component, of its gangue, comprising heating the ore together with its iron component and its gangue, crushing the resultant material, screening the resultant material, tumbling the oversize to loosen the gangue from the ore, and subjecting the oversize to a blast which removes the gangue from the ore.

10. The process of clearing ore, having iron. as an! economic'component, of its gangue, comprising heating the ore together with its iron component and its gangue, crushing the resultant material, screening the'resultant material, heating and tumbling the'oversize to loosen the gangue from the ore, and subjecting the oversize to a blast which removes the gangue from the ore.

11. The process of clearing ore, having iron as an] economic component, of its gangue, comprising preliminarily heating the ore together with its iron component and gangue to drive 05 the free moisture, crushing the ore and gangue, then subjecting the oreand gangue' to a separate heating operation to drive oti' the volatile matter, and separating the gangue'from the ore.

12. The process of clearing ore, having iron as an economic component, of its gangue, comprising heating the ore together with its iron component and gangue to drive off the free moisture, crushing the ore and gangue, heating the ore and gangue to drive off the volatile matter, tumbling the ore and gangue to loosen the gangue from theore, and subjecting the ore and gangue to a blast which separates the gangue from the ore.

18. The process of clearing ores, having iron as an economic component, having clay as a gangue and containing both free and combined moisture. comprising preliminarily and gradually heating the ore together with its iron component and its gangue to drive 0d the free moisture, crushing the ore and gangue so treated, heating the crushed ore and its gangue to drive off the combined moisture, tumbling the ore and its gangue to loosen the gangue from the ore,'and subjecting the ore and its gangue to a blast which removes the gangue from the ore.

lln testimony whereof We have hereunto afiixed our signatures in the presence of these witnesses.

EDWARD F. GOL'IRA. THOMAS S. MAFFITT. JESSE D. DANA. Witnesses;

W. A. S'rrnn, P. C. MAFFI'IT.

ROBERT W. EltWlN. Witnesses:

HARRY Oar,

FRANK CAMPBELL.

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