US 3385436 A
Description (OCR text may contain errors)
May 28, 1968 c. A. MURPHY PNEUMATIC CONCENTRATOR 5 Sheets-Sheet 1 Filed May 31, 1966 OON vON QON 1 1 n LRQ INVENTOR. CHARLES A. MURPHY ATTORNEY y 8,196s c. A. MURPHY 3,385,436
PNEUMATIC CONCENTRATOR Filed May 31, 1966 3 Sheets-Sheet 2 CHARL MURPHY INVENTOR.
wig/M ATTO R N EY May 28, 1968 c. A. MURPHY 3,385,436
' PNEUMATIC CONCENTRATOR Filed May 31, 1966 3 Sheets-Sheet 3 ATTORNEY United States Patent 3,385,436 PNEUMATIC CONCENTRATOR Charles A. Murphy, Buckeye, Ariz., assiguor to V. B. West, Amarillo, Tex. Filed May 31, 1966, Ser. No. 554,163 6 Claims. (Cl. 209-135) This invention relates to an apparatus for pneumatic concentration of ores and the process of its operation. More particularly this invention is directed to a process for concentration of flaky ore material such as mica.
While the treatment of mixtures of materials of varying shapes and gravity have been the subject of delicate and involved mathematical analysis such as Gaudin, Principles of Mineral Dressing, McGraw-Hill, New York, 1939, p. 197, in separating materials of disparate size as well as specific gravity there have been differences of opinion as to the best method of separation of the various fractions of ore by pneumatic separators, e.g., Taggart, Handbook of Mineral Dressing, Wiley & Sons, New York, 1945, section 9, pp. 29-30 teaches that in air separators air classification is a sizing rather than a sorting operation because difierences in specific gravity are not utilized yet also teaches (section 9, p. 32) that all modern commercial air classifiers use inertia and gravitational forces in combination. Further, the discontinuous character of the discharge from such machines upsets the balance therein.
Accordingly, while much work has been done to approximate species of smooth curves to characterize the operation of apparatuses for air classification of solid particles, such apparatuses have been complex to operate practically as well :as to set up theoretically.
These past difiiculties have been met by compromises between theoretical curves for intended operational characteristics and, thereover, approximations to compensate for irregularities in classifier discharge and the effect thereof on the operation of the classifier. In large operations, where suiliciently substantial volumes of each fraction may be obtained to form a screw conveyor seal, steady state operations are obtained, but close cuts are not made because such apparatus not only are adapted only to very large scale operations, but the number of cuts are limited by the size and cost of such screw conveyors and also the time delay to determine and correct for ore variation is so long that, in practice, only one setting is made for a given ore and variations in the operation of the apparatus are absorbed in the product.
Such apparatuses are not adjustable to small scale operations and rapid changes in ore composition as well as being expensive to construct and slow to effectively control.
This invention is directed to overcome the obstacles heretofore met by the prior art by a novel apparatus and the process of its operation.
This invention teaches an apparatus and process of operation thereof that is simple, rapid, inexpensive and reliable, notwithstanding prior involved mathematical operations, by achieving steady state operations. Herein the conditions of air velocity and rate of solid feed and of discharge are maintained constant; notwithstanding the variations in particle size of the feed the same shape and size of particles of each mineralogical species achieves the same selective sharp path and, are selectively recovered by use of a multiplicity of fine cuts. Further, the recovered fractions obtained are closely sized and uniform because also, of the incorporation in the apparatus of a novel discharge mechanism which provides no interference with the air flow and avoids the turbulence in critical regions that atfect the final path of small particles. The
3,385,436 Patented May 28, 1968 operation of the process is readily followed and quickly controlled.
One object of this invention, accordingly, is to provide a new and useful apparatus for the separation of particles of different sizes and shapes.
Yet another object of this invention is to provide an improved discharge apparatus for an air separation apparatus.
Yet another object of this invention is to provide an improved process of operation of an air separator.
Other objects of this invention will become apparent to those skilled in the art upon a study of the below description thereof and of the herewith provided drawings, which drawings form a part of the description of this invention and in which drawings the same reference numeral refers to the same part throughout and wherein;
FIGURE 1 is an overall diagrammatic longitudinal section view of a preferred embodiment of an apparatus, 10, according to this invention;
FIGURE 2 is an enlarged view of zone 2A of FIG- URE 6;
FIGURE 3 is an enlarged diagrammatic view of subassembly 16 of apparatus 10;
FIGURE 4 is a horizontal sectional view along section 44 of FIGURE 1; it shows the arrangement of and the tops of the orifices of the discharge valves;
FIGURE 5 is a longitudinal vertical section along plane 5-5 of FIGURE 6;
FIGURE 6 is a transverse vertical view along plane 66 of FIGURE 4 and shows a front view of a discharge valve subassembly 109 according to this invention;
FIGURE 7 is an enlarged view of zone 7A of FIGURE 1; and
FIGURE 8 is a side view of the chamber 12 of apparatus 10 as seen along direction of arrow 8A of FIGURE 4.
A preferred embodiment of apparatus 10 of this invention comprises, in operative combination, an air deflection chamber assembly 20 in series with a fan and air circulating duct subassembly 22 and a chamber discharge collection and conveyor subassembly 25.
Chamber subassembly 20 comprises a chamber 12 and, operatively connected thereto at its bottom, a discharge valve subassembly 14; at its top, a feeder subassembly 16; on one, inlet, side, 15, an inlet to an outlet of subassembly 20 and a louvre subassembly 18; and on the other, outlet, side, 56, an outlet to an inlet of subassembly 20.
Chamber 12 is, generally, an enclosed horizontally extending conduit open at its inlet and outlet ends for passage of air therethrough and to a lesser degree at its top and bottom for passage of ore therethrough.
It has a vertical front wall 26, a vertical rear wall 27, a horizontal top wall 28 and a horizontal bottom wall 29. Except for the feed inlet orifice 17 and openings to pressure test instruments 36A and 36B and a mechanically closed, optically transparent glass window 360, the top wall is imperforate; the vertical rear wall 27 is imperforate except for test orifices 87A, 87B, 87C, 87D and 87E each connected to instruments as 186B-D and the closed glass windows 187A and 187B for observation. The front wall is imperforate except for test orifices 86A, 86B, 86C, 86D and 86B for test instruments attached thereto as 88A, 88B, 88C, 88D and 88B, respectively, and transparent and closed observation windows 188A and 188B. These windows are imperforate and transparent. The interior surface of each of the walls 26, 27 and 28 is smooth. The bottom wall 29 is provided with a multiplicity of orifices within which are seated the tops of the components of valve subassembly 14.
Each vertical wall, as 26, is provided with pressure sensing and indicating devices 86A, 86B, 86C, 86D and .3 86E; these are U-tubes, filled with water, to show pressure differences between the atmosphere and the portion of the chamber 12 to which connected.
On the rear wall the herein similar sensing devices 186B, 186C and 186D correspond to U-tube indicators 88B, 88C and 88D; such are located at top and bottom and inlet and outlet end center portions of each vertical wall as shown in FIGURES 1 and 8. Similar pressure sensing and indicating devices 152, 153, 155, 157 and 159 and 158 are provided at conduits 32, 53, 55, 57, 67 front and 67 rear, respectively.
The circulating duct subassembly 22 comprises an air inlet pipe with an air intake damper 31 operatively connected thereto. Damper 31 is an adjustable gate valve. Air intake line 32 operatively connects the pipe 30, via gate valve 31 to a centrifugal blower fan through a conduit Y 49. Fan 40 is operatively connected to and actuated by a standard electric motor 42. The fan 40 comprises a multiplicity of blades as 44 and 45 rotatably supported within a fan blade chamber 47. The inlet 46 to the fan blade chamber 47 is operatively connected to one arm of the inlet Y 49. The line 32 opens into another arm of the inlet conduit Y 49. An adjustable inlet damper gate valve 51 is provided at the top of the conduit Y 49 and is operatively connected thereto. A vacuum line 53 is serially and operatively connected at its bottom, discharge, end to the valve 51 and, thereby to another arm of the Y 49. The line 53 is operatively connected at its top, inlet, end to the discharge end 56 of the chamber 12 by a gradually and uniformly tapered chamber discharge conduit 55. The subassembly 22 also includes the connections from the discharge end of the fan 40 to the inlet end, 15, of the deflection chamber 12. This portion of the subassembly 22 comprises an upright fan discharge duct 57 which connects the outlet 48 of the fan chamber 47 to an upper exhaust damper valve 59 and inlet volume control damper 61. The inlet damper 61 is operatively connected to the deflection chamber charge conduit 63. Conduit 63 is operatively connected to the inlet portion 16 of chamber 12.
Within the chamber 12 at its inlet side, 15, is a louvre subassembly 18; the inlet conduit 63 enters at the outer end of the inlet portion 15 into a flared conduit 67. A perforated grill 66 (perforated with circular holes) separates the conduit 63 from the flared portion 67 and serves to even out the air flow through conduit 67 and thereby avoids having the air flow through the flared portion 67 flow primarily through the center thereof. The distribution is accomplished by that there are somewhat smaller holes in the center of the grill 69 and larger holes at the top and bottom and sides thereof, with the diameter of holes being smallest at the center of the grill and increasing in diameter linearly toward the periphery. A pair of rigid perforated plates 71 and 73 provide an equalizing chamber 75 therebetween to provide for an evenly distributed and relatively static pressure in the chamber 75. In the preferred embodiments, plates 71 and 73 are punched plates with the axis of each of the orifices in one plate not in a horizontal line with the axis of an orifice in the other of the two plates. Thereby the air flow through those plates is not directed in any one direction and a relatively static pressure is developed within the chamber 75 between the plates 71 and 73. The perforations in each of the plates 71 and 73 are equispaced and provide for equal distribution of orifice area through the area of both plates.
The louvre subassembly 18 includes a multiplicity of like sets of louvres as 77, 79, 81 and 83. Each of these sets is arrayed to provide, in cooperation with the others, a laminar flow of air through the interior of chamber 12. The set of louvres 77 comprises a series of identically shaped and sized louvres as 77A, 77B, 77C and 77D and the handles therefor exterior to wall 26 as 78A and 78B. Each of the louvres as 77D is straight, i.e., they each extend from one, front, side to the other, rear, side of the chamber 12. The upper and lower surfaces of each louvre member as 77A are curved and are symmetrical about the horizontal central plane for each louvre. The members of each set of louvres as 77A, 77B and 770 are arranged with their pivotal axis, which axis is also their central axis, horizontal and in a vertical plane which plane is perpendicular to the walls 26 and 27: corresponding louvre members 79A, 79B and 79C of set 79 are arrayed with their pivotal axes in a vertical plane parallel to the vertical plane in which the centers of louvres 77A, 77B and 77C are arrayed. Each of the louvres as 77A of each set as 77 are pivotally adjustable and they are all pivotally located on horizontal axes parallel to each other and in the same vertical plane. Each member as 77B of set 77 is equally off-set from its neighboring member as 77A and 77C. Each of the members 79A, 79B and 79C of the set of louvres 79 is equally vertically off-set from the center lines of members 77A, 77B and 770. Each of the members of another vertical set of louvres, 81, is arrayed in a vertical plane parallel to plane of the center lines of the louvres as 77A, 77B and 77C, respectively, with the centers of each of the separate louvres of set 81 vertically spaced from each other and at the same height as are the nearest of the louvres in the series of louvres 77A, 77B and 77C. Another set of louvres 83 is arrayed with the center lines of the members thereof parallel to the line of louvres of set 81, but off-set therefrom in the same manner as each of the members of set 79 is off-set from the members of set 77. In the set 83 the centers of each louvre 83A, 83B and 83C is the same height over the floor of the chamber 12 as are the centers of louvres 79A, 79B and 79C. The space left between the members of each set of louvres of sets 81 and 83 is the same as the spacing between the members of set 81 and 79 and between the members of set 79 and 77. Accordingly, there is created by this apparatus a laminar flow of the air through the chamber 12 with all the laminae traveling at the same horizontal speed. The adjustability of each member, as 77A, is effected by its handle 78A (778 by its handle 78B) and corrects for any manufacturing errors and adjusts the air flow in chamber 12.
The discharge valve subassembly 14 comprises a series of about 20 like discharge valves as 91-110. Each of these valves is, as seen from above, rectangular in shape and elongated transversely to the length of the chamber 12, i.e., transverse to the length of the chamber as measured from its inlet side 15 to its outlet zone 56.
The bottom wall 29 of the chamber 28 is composed of a series of about 20 horizontal separators, as 111-129, each joined at their rear and front to a rear edge strip 89 and a front edge strip 90, respectively, and end strips A and A. Each of the outlet valves as 108 and 109 are located between and supported on two of the neighboring separator strips as 127 and 128 (for 108) and 128 and 129 (for 109) as in FIGURE 5.
Each discharge valve assembly, as 109, comprises a closure subassembly as 130, a discharge guide sleeve subassembly as 132 and a frame as 160. Each closure subassembly as 132 is supported by and attached to its frame as in an air-tight manner. Frame 160 is a rigid rectangular frame which encloses the elongated rectangular oriflce 149 of the valve 109 and is firmly attached to the side and end walls therefor (138, 140, 142, 144, below described).
Each of the frames as 160 has at its outlet side a rigid flat vertical imperforate ridge plate 137 that extends from wall 26 to wall 27. Its upper edge is horizontal and smooth and chisel shaped with a sharp upper edge. This projects upward to make a sharp separation between adjacent pockets and precludes passage of ore accumulated between two different pockets from passing into that pocket (as 130) within the frame which supports the ridge.
The closure subassembly 130 fits inside the discharge guide subassembly 132 therefor. Each closure subassembly comprises a relatively flexible pocket 134 and a tension adjustment bar subassembly 136 attached to the bottom thereof and supported thereon. Each pocket 134 is attached to the frame therefor, as 160, in a substantially air-tight manner. Each pocket as 134 is formed of a sloped and flexible left side wall as 138, a sloped flexible right side wall as 140, a sloped flexible rear wall 142 and a sloped flexible front wall 144. The bottom edges of the side walls 138 and 140 are held close to and parallel with each other by the subassembly 136 and are of the same length. The side Walls and the end walls are imperforate and air-tight in the preferred embodiment although filter cloth is adequately imperforate. The walls 144 and 142 are joined at their left and right edges to walls 138 and 140, respectively. This joining is accomplished in a continuous and air-tight manner. Accordingly, each pocket as 134 has an upper elongated rectangular opening as 149 and a lower orifice zone 150 between the bottom portions of the flat left and right side walls. This structure has an open slit at its bottom when the apparatus is at rest but is effective as a closure against air passage into the chamber 12 during operation of the apparatus 10. However, the close approximation of the bottom edges of walls 138 and 146 does not preclude the passage of solid material downward therepast for reasons below set out.
The tension adjustment bar subassembly 136 comprises a U-shaped bar 146, a center tension spring 145, a rear tension spring 143 and a front tension spring 141 operatively attached thereto. Bar 146 has a reai upstanding spring supporting arm 147 and a front upstanding spring supporting arm 148; a threaded rear spring adjustment nut 151 is attached by threads to a spring holding threaded screw 153 which is thereby adjustably located in the arm 147. Screw 153 is firmly attached at its front end to the rear end of tension spring 143. A front spring adjusting nut is attached to a spring holding screw similar to 153. This screw holds spring 141 and is held in the arm 148 and is adjustable by the nut attached thereto in the same manner as shown for 153. The spring 141 urges the front lower edge of pocket 134 to arm 148. Springs 141 and 143 are each attached by a grommet therefor to the front and rear ends of the pocket 134 near to the bottom thereof, and slope downwards and outwards to arms 147 and 148 at about 30 to the horizontal. Spring 145 is attached to the center of arm 146 and to the lower edge of the pocket 134 slightly above the bottom edge of the pocket. It helps keep the bottom edge of the pocket in a straight line with the help of the weight of the arm 146 and rigidity of that arm. Bar 146, and arms 147 and 148 are smooth surfaced and fiat. The bar 146 is made of metal and is rigid; /3 inch steel stock is adequate. Spring 145 extends vertically.
The tension in the spring resiliently keeps the bottom edges of the pocket parallel to and close to each other and thereby maintains a straight and thin lower orifice therebetween.
The upper edge of the walls of pocket 134 are attached to and supported on the interior edges of the orifice 149 in the rigid rectangular frame 160. The frame 160 is elongated transverse to the length of the chamber 12. The attachment of the walls of the pocket to the frame 160 is an imperforate and air-tight connection.
The discharge guide sleeve subassembly 132 is firmly attached to the bottom of frame 160 and comprises an upper rectangular generally air-tight imperforate canvas sleeve portion 162 that surrounds the pocket 134. The guide sleeve subassembly 132 also includes a lower triangular portion 164 firmly attached to and continuous with the bottom of upper sleeve portion 162. Portion 164 terminates at its bottom in a lower orifice 166. The discharge guide sleeve subassembly 132 surrounds a chamber 167 into which the contents of pocket 134 may be discharged without contamination with the products of other similar products from other pockets located at different positions along the length of the bottom of chamber 12. The bottom front and rear walls of the guide sleeve 132 at its triangular portion 164 are flexible and arranged at an angle to the horizontal greater than the angle of repose of the material to be collected, 60 in the preferred embodiment. Hence, it may be shaken and moved readily and even at rest there is no accumulation of material in that sleeve.
In the operation of the apparatus 10 the somewhat greater pressure outside of chamber 12 and within the upper portion of the guide sleeve 132 causes the walls as 138 and 140 to assume a curved shape convex toward chamber 12 as shown in FIGURE 5. This curvature is the resultant of the weight of the bar 146 and the difference in pressure between the pressure outside of chamber 12 as in chamber 167 and the pressure inside chamber 12. The difference is due to the rate of flow of gas and solid material through the chamber 12 and the vacuum created by fan 40. The action of this relative vacuum to form a curved surface all across the length of each of the walls as 138 and 140 is attenuated by the weight of the bar 146 and the action of its springs 141, 143 and 145 keeping the lower orifice open for the valve 109; for all the other valves in subassembly 14 of the apparatus 10 the coaction of pocket walls, air pressure and tension bar is the same. Accordingly, in operation of apparatus 10, as below described, the side walls as 138 and 140 of each valve as 109 are approximated to each other by the difference in pressure between that in chamber 12 and that exterior thereto as in 167. Thereby a very gentle yet definite closure action is effected. This is a very gentle closure action and permits the accumulation of sized particulate matter in the pocket 109 and, on accumulation of a definite yet small weight thereof adequate to force open a portion of the orifice 150, to discharge a portion of that accumulation in that pocket portion automatically along each portion along the length thereof, with some accumulation still remaining in the pocket. This action of discharging and sealing occurs at each portion of the pocket independently of the action at another portion of the pocket distant therefrom and without causing any surges of air current although there is only a very light accumulation in the pocket and only small amount of discharge at any one time. This structure thus prevents the passage of air upward through each valve as 109 notwithstanding that the valve (and other valves like it) has a substantial width (as measured transverse to the length of chamber 12) and this action on each valve, as 109, is substantially the same all through the width of each valve. The tension of springs as 141 and 143 and 145 keep the bottom edges of each pocket in a straight line and maintain the curvature of the pocket substantially constant throughout its width, i.e., from the rear edge to the front edge of each pocket.
Each sleeve, as 132, has a flap as 163 lateral to and at the same vertical level as each adjustment screw and nut, as 153 and 151 for the rear valve 109, on each end of such sleeve and the flap 163 has a snap 164 for holding the flap closed. A similar flap (163A) is on the front of sleeve 132 to provide for adjustment of the spring 141 and all sleeves have similar flaps to facilitate access to and adjustment of the tension across the bottom of each pocket of each valve.
The difference in pressure from chamber 12 to the outside thereof (i.e., to the chamber 167 for the valve 109) is in the embodiment below described only about 10" water or about /3 pound per square inch. There is usually only a height of about /go pound of material per linear inch in the pocket 109 and yet the opening is automatic and the closure complete.
Adjustment of the tension of the springs 141 and 143 as below described provides that a greater or less accumulation provide for an automatic dis-charge of the additional material accumulated in the pocket through the bottom orifice of that pocket. The valves as 109 thereby each provides for an automatic valve opening which does not create any air disturbance over the top of the valve and permits a constant set of conditions to be operative over the bottom fioor of the chamber 12 although the quantitative amount of ore in each pocket be small. To collect the pocket discharge, open topped transparent containers 191-210 are provided under each of the orifices (as 166 on 109) for each valve, as 91-110, respectively. The orifice of each discharge guide (as 166 for valve 109) for each valve fits into and extends slightly below the open mouthed top of each such container as container 209 for valve 109. The bottom of each guide sleeve as 132 is made of flexible cloth, hence is easily removed from the container as well as closed otf (by folding) when containers are exchanged during operation of the apparatus 10.
The chamber discharge collection and conveyor assembly 25 comprises the containers 191-209, the mixer 181 and the conveyor 171. The containers 191-209 are transparent glass or vinyl jars that permit visual observation of the contents and ready removal of a portion thereof for optical inspection by a low power microscope. The mixer 181 is a conventional mixer for use in starting up the process as above described. The conventional ore conveyor 171 is fed from mixer 181 and discharges to hopper 172. 181 is hand-fed. The feeder subassembly comprises a hopper 172, a star wheel and a distributor and chute. Hopper 172 has a bottom sloped, at a 50 angle to the horizontal, and is open at its bottom, 173, to a star wheel chamber 174 wherein a standard star wheel 175 is driven by a motor 179. Motor 179 is connected to a belt drive 180 to a large size star wheel drive pulley 169. The star wheel discharges the to-be-separated ore 11 onto a distributor 176 which passes the ore via V- shaped chute 177 into orifice 17 in the top wall 28 into the chamber 12. The ore is fed at a constant rate into the chamber 12: the ore provides a seal in chute 177 and the atmospheric pressure urges the ore through lower chute orifice 173. Distributor bottom 176 is corrugated transverse to the direction of ore passage thereover to equalize the amount of ore distributed to each portion of the chute 177 and orifice 17. Orifice 17 and the bottom of chute 177 each extend the full width across chamber 12. A slidable closure plate 178 across the bottom of chute 177 controls the flow through chute 177, which has an open top.
In operation feed is added to the hopper 171 and chute 177 and the valve plate 178 closed and the fan 40 is set in operation by the motor 42. This develops a negative pressure at the air inlet 30 as measured at indicator 152 and a positive pressure at the exhaust discharge valve 59 (and measured at 157) and also at the chamber 67 as measured at 157 and 158. Valve 59 is adjusted to discharge fines and valve 61 is adjusted to maintain a small but positive pressure at indicator 159. The valve 51 is adjusted to provide a negative value of several inches of water at 153. Valve 31 is adjusted to compensate for loss of air at valve 59 but the inlet volume is kept low so that the vacuum as measured at 152 is not so far below that at 153 to permit proper operation of the pockets as 134 of the valves 91-110.
The valve 51 is adjusted to develop a negative pressure at 153 and a pressure drop across the louvre assembly 18: this is facilitated because of the absence of louvres between the feed inlet 17 and the valve 51. Accordingly, after the fan has been set in operation there is a slight negative pressure at the orifice 17 (measured at 88A). Then ore is moved from hopper 172 to chute 177 by star wheel 174 and the reading on the pressure gauge 88B is compared to the reading on 88B to see if there is any leakage through the chute 177. More ore is added to chute 177 until 88A and 888 read the same. The louvres may be adjusted to provide the pressure at 8813 and 88C to be the same and at a slightly definite negative value. The negative pressure at 88A and 88B is also adjusted by the louvres and gate valves to be the same as each other although definitely a less negative value (higher absolute value) than 88E and 88C. These pressure readings indicate the proper how of the air through the chamber 12. There is thus a definite vacuum created in the chute 17 and thence evently and steadily through the orifice 17 into the chamber 12 all across its width. Feeding is continued for about 20 minutes at the end of which time the above described pressure relationships are the same as above described. That is, the pressure at 8815 and 880 is the same and the values shown there are negative values. The pressure reading devices at 88E and 88C may be conventional U-tubes which are read in inches of water. They are open to the atmosphere at the top. The adjustment springs 141 and 143 may then be adjusted for a continuous rate of discharge through the bottom edges thereof while (as per observation as through Window 188A) keeping a seal of ore in each pocket. This is done by unbuttoning a flap as 163, adjusting the adjacent spring as 141 and a similar flap as 163A adjacent spring 141 in order to turn the adjustment nuts (as 151) therefore. This adjustment provides for an even discharge of ore through the bottom of each pocket and a suppression of any air flow upward through the orifices as 149.
A light is provided at window 360 and 187A and 187B. This permits visual observation at windows 188A and 188B of the flow of gas and mineral particles through chamber 12 and permits the operator to observe the laminar flow of the material through the chamber. Some minor adjustments may be made for any or all of the louvres by the louvre handles (as 78A, 78B for louvres 77A and 77B). It is to be noted that this apparatus provides that there is substantially no pressure drop from the set of louvres closest to the interior of the chamber 12, i.e., set 77 and the outlet 56 of the chamber 12. Negative pressure exists throughout the entire chamber 12. This also provides that, while there is the least negative pressure near the feed inlet 17, this is the zone in which the heaviest ore falls to its discharge valve, as 91. Accordingly, the adjustment on the pockets provides for the largest pocket discharge opening near to the inlet 15. However, such size slit as is provided by the springs acting across the bottom of the pocket is adequate, as the air flow for such ore is not critical and the size of slit is adequate for its purpose especially as it is adjustable. Near the outlet etnd 56 of chamber 12, where the ore fractions are the lightest and the most delicate of adjustments is necessary for separation of the ore fractions, the pressure differential between the interior of the chamber and the exterior thereof is the greatest and the closest and most delicately controlled seal is formed by the left and right walls, as 138 and 140 of each pocket, as 134, as above described.
The product of the ore separator is collected in the containers 191-210 and the apparatus is then ready for its continuous operation. For this purpose the samples collected during this 20 minute period are returned to a mixer, as 181 and thence, to a mixer bin as 182, and thence, to the feed conveyor 171 for return to the hopper 172.
At this point the apparatus is now in a steady flow state and the discharge outlet subassemblies as 109, and 106 which may be producing fractions which are us ful and valuable are collected and saved. The other fractions may be sent to waste by conveyors or simply collected in baskets.
After a sutficient volume of any one fraction (e.g., at 209) is collected to fill the hopper 172 all the other containers as 201-7 may be emptied and the material caught on the first run of concentration be refined using the apparatus as its own cleaner, following what might be regarded as the roughing operation theretofore made. It is important that the fan and motor 40 be started prior to adding ore to chamber 12 so that the pockets will be closed by the vacuum sealing action above discussed.
It is to be noted that the valve action of each discharge is accomplished with no loss of the gaseous media while the solid feed is being discharged from the bottom of each pocket and its corresponding sleeve. Accordingly, there is no interference with the steady flow of the gaseous media throughout the apparatus from the inlet portion as 15 to the outlet thereof. The windows especially permit the observation of the flow pattern and the tension on each of the pockets as 134 is readily adjusted even during the operation of the apparatus depending on optical inspection (at 50 and 100x) of the product delivered to each container as 209.
In a particular preferred embodiment of apparatus and operation thereof, the ore treated was 75% muscovite mica and 25% quartz, feldspar and iron oxide. The ore is ground to 100% through 20 mesh (U.S. standard) from 2" run of mine ore. The material discharged at valve 59 is between /2 and 1% by weight of the material fed and is all -325 mesh (U.S. standard). The dimensions of the apparatus 10 are as in Table I.
TABLE I Apparatus 10 dimensions Chamber 12 Interior Width (26-27) 3'6" Interior height (28-29) 3'0" Total length (66-130A) 9'8 Open chamber length (130-77) 6'0" Valves, number of valves as 109 23 Closure 134, height (bottom edge-top edge) Width orifice 149 (26-27 direction) 35% Length orifice 149 (91-129 direction) 2" Length orifice 147 30 Wall material, sailcloth canvas. Sleeve 132 material, canvas. Portion 162 height 7" Portion 164 height 20" Tension bar 136:
Length 34%" Weight 2# Thickness A5" Height arm 147 4" Tension in spring 141 lbs 2-10 Ridge 139, height 1" Louvre 77:
Length 3" Thickness (vertical) /2" Spacing between rows 77 and 79 center line- 3" Spacing between top of louvres 77A and the bottom of 77B /2" Chamber 18, length 12" Plates 71 and 73, diameter holes in 1%" /2" thick plywood.
There are 23 pockets as 109 in the apparatus (20 were used in the above discussion for purpose of simplicity of description of related parts e.g. 91-110, 111-129, 191- 210). Each of the ore fractions thus obtained varied less than 110% in diameter: there was, by optical inspection, less than 1% of overlap between adjacent sized fractions of mica obtained, hence each pocket produced a fraction substantially all within one standard United States mesh size, e.g., 98% --35 mesh, 98% +40 mesh.
Although in accordance with the provision of the patent statutes, a particular preferred embodiment of this invention has been described and the principles of the invention have been described in the best mode in which it is now contemplated applying such principles, it will be understood that the operations, constructions and compositions shown and described are merely illustrative and that my invention is not limited thereto and, accordingly, alterations and modifications which readily suggest themselves to persons skilled in the art without departing from the true spirit of the disclosure hereinabove are intended to be included in the scope of the annexed claims.
1. In a pneumatic ore separator, operatively connected, a settling chamber, a fan, a conduit, a feeder for said chamber, said settling chamber having a top wall, a rear wall, a front wall, an inlet zone and an outlet zone, the inlet of said fan being operatively connected to the outlet zone of said settling chamber, said feeder being attached to and discharging through the roof of the chamber near its inlet zone, and discharge outlets elongated transverse to the direction from the inlet of said settling chamber to the outlet of said settling chamber, said discharge outlets being located consecutively along the floor of said chamber,
each of said discharge outlets comprising flexible pocket means, sleeve means, and a frame support, said frame support being a hollow rectangle surrounding an elongated rectangular orifice, said pocket being attached to said frame, said sleeve being attached to said frame, said frame being attached to and supported on the floor of said chamber, each said pocket comprising -a left wall, a right 'wall, a front wall and a rear wall, said front Wall and rear wall each being generally V-shaped, said left and right wall-s having a top and bottom edge, each bottom and top edge on each Wall being generally parallel to each other, said walls all being flexible and imperforate, a rigid spring supporting means below said pocket, a front tension spring extending between the bottom of the front end of said pocket and the front end of said support, a rear tension spring extending from the bottom of the rear end of said pocket to the rear end of said bar, the front end of said bar extending frontwards of the front end of the bottom of the pocket, the rear end of said bar extending rearwards of the rear end of the bottom of said pocket.
2. Apparatus as in claim 1 comprising also pressure measuring and indicating means on the walls of said chamber and ducts to operatively connect the interior of said chamber and said means; a Y with one arm there of connected to said fan outlet, another arm of the Y connected to the atmosphere, a valve in said another arm of the Y, said inlet of said chamber connected to the third arm of the Y, and :a valve in said third arm, a second Y connected to the inlet to said fan, a valved conduit connected at one end to one arm of that second Y and at another end to the atmosphere; another arm of that second Y connected to the outlet of said settling chamber through a valve.
3. Apparatus as in claim 2 comprising also a plurality of louvres in the inlet portion of the chamber, all on the inlet side of the inlet of the feeder into said chamher and no louvres between said feeder inlet and the chamber.
4. Apparatus as in claim 3 comprising also a sleeve surrounding the pocket and being attached to said frame, said sleeve having a lower portion which has an orifice at the bottom and which lower portion has side walls which are sloped and terminate adjacent said orifice, a separate receiver below each said orifice.
5. In a pneumatic ore separator a discharge outlet comprising flexible pocket means and a frame support, said pocket being attached to said frame, said frame being a hollow rectangle outlining an elongated rectangular orifice, said pocket comprising a left wall, a right wall, a front wall and a rear wall, said walls being flexible and imperforate, said front wall and rear wall being generally V-shaped, said left and right wall each having a top and bottom edge, said edges of each wall being generally parallel to each other, a rigid spring supporting means below said pocket, a front tension spring extending between the bottom of the front end of said pocket and the front end of said support, a rear spring extending from 1 1 1 2 the bottom of the rear end of said pocket to the rear end References Cited of said bar, the front end of said bar extending frontwards of the bottom of the front end of the pocket, the rear end UNITED STATES PATENTS of said bar extending rearwards of the bottom of the rear 309,043 12/1884 G y 209-435 end of said pocket, adjustment means between each said 5 9 Tltchmarsh 209l35 spring and said support bar. 3,167,089 1/1965 Gordon 137525.1
6. Apparatus as in claim 5 comprising also an air-tight flexible sleeve surrounding the pocket and being attached HARRY THORNTON Primary Examilm. to said frame, said sleeve having a lower portion which has an orifice at the bottom and which lower portion has side 10 TIM R. MILES, Examiner. walls which are sloped and terminate adjacent said orifice.