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Publication numberUS3114510 A
Publication typeGrant
Publication dateDec 17, 1963
Filing dateMar 1, 1961
Priority dateMar 1, 1961
Publication numberUS 3114510 A, US 3114510A, US-A-3114510, US3114510 A, US3114510A
InventorsCurtis Charles H, Mccarty James P
Original AssigneeDuval Sulphur & Potash Company
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Sensing and control apparatus for classifiers
US 3114510 A
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Description  (OCR text may contain errors)

Dec. 17, 1963 J. P. M CARTY ETAL SENSING AND CONTROL APPARATUS FOR CLASSIFIERS Filed March 1, 1961 2 Sheets-Sheet 1 GRINDING MILL CI/zcu/r a I l ,8 22 EXHAUST R! [9a 19 u 42 a L 1' 40\ i i 37 I i 31 L "fi'.

0- SUPPLY JAMES R MCART) Cl/A/FLES H. CggPf/S A TTORNE Y5 Dec. 17, 1963 J. P. MCCARTY ETAL 3,

SENSING AND CONTROL APPARATUS FOR CLASSIFIERS Filed March 1, 1961 2 Sheets-Sheet 2 ORE PROPER SIZE FIN/SHED MATERIAL INTAKE STORAGE CONTRGL VAR/ABLE I .spsso CONTROL 47 GRIND/N6 MILL PUMP JAMES I? M CAIRT) CHARLES H. CURTIS INVENTORSI United States Patent 3,114,510 SENSING AND CONTROL APPARATUS FOR CLASSIFIERS James P. McCarty and Charles H. Curtis, Tucson, Ariz.,

assignors to Duval Sulphur & Potash Company, Houston, Tex., a corporation of Texas Filed Mar. 1, 1961, Ser. No. 92,695 18 Claims. (Cl. 241-3 4) This invention relates to new and useful improvements in a sensing and control apparatus for cyclone classifiers. More particularly, it relates to the control of the underflow discharge of a cyclone classifier by sensing the configuration of the pattern of said discharge.

As is well known, classifiers of the cyclone type comprise a cylindrical upper body section and a lower conical section and utilize centrifugal force to effect the classification or separation of material. Experience has shown that the configuration or pattern of the underflow discharge of the cyclone varies from axial under overload conditions to a flaring wide-angle discharge under underload conditions, so that said configuration or pattern is directly related to operation conditions and, therefore, is indicative of the separation efficiency of the classifier. Overloading of the cyclone results in undesirable coarse material being carried over into the overflow section and discharged with the proper size finished material; on the other hand, during underload conditions finished material is undesirably carried out in the underflow. The existence of either of these conditions, that is, underload or overload, interferes with optimum separation and maximum efficiency of operation. Since the configuration or pattern of the underflow discharge is responsive to overload or underload conditions, said pattern provides an accurate and convenient indication or measure of the separation eflEiciency of said classifier.

It is therefore the primary object of this invention to provide a sensing apparatus for accurately sensing the configuration of the underflow discharge pattern of a cyclone 'whereby said sensing means provides information as to said configuration and, therefore, information as to the efficiency of operation of said unit as represented by the configuration of the underflow discharge.

An important object of this invention is to provide a control apparatus having means for maintaining the configuration or pattern of the underflow discharge of a classifier within certain predetermined limits to thereby maintain the operation of the classifier within an eflicient separation range.

A further object is to provide control apparatus for cyclone classifiers which will automatically control the configuration of the underflow discharge by automatically varying the size of the underflow discharge orifice or apex valve of said classifier in response to a change in said underflow discharge configuration.

A still [further object is to automatically control the configuration of the underflow discharge by automatically varying the input load to the cyclone in response to a change in the underflow discharge pattern.

Another object is to provide an improved apparatus of the character described which lends itself to use with a single control means or with a combination control means for effectively varying and controlling the configuration or pattern of the underflow discharge and which may, if desired, be utilized to actuate an alarm or signal, such as a bell or light.

Another object is to provide an improved apparatus of the character described which lends itself to use with a single control means or with a combination control means for effectively varying and controlling the configuration or pattern of the underflow discharge of cyclone classifiers and which may, if desired, be utilized to regu- 3,114,510 Patented Dec. 17, 1963 2 late the rate of feed input to a grinding circuit in order to maintain the desired volume of circulating classifier sand load for eflicient closed circuit grinding operation.

The construction designed to carry out the invention will be hereinafter described, together with other features thereof.

This invention will be readily understood from a reading of the following detailed description and reference to the drawings wherein:

FIGURE 1 is a diagrammatic illustration of one embodiment of the present invention wherein the signal generated by the sensing means is utilized to vary the size of the underflow discharge orifice, and

FIGURE 2 is a diagrammatic illustration of a second form of the present invention wherein the signal generated by the sensing means is utilized to automatically vary the input load to the cyclone.

Referring now to FIGURE 1, the conventional cyclone classifier 10 comprises an upper cylindrical section or feed chamber 11 and a conical or tapered section 12 which extends downwardly from said upper section or chamber 11. The upper section 11 has a tangentially disposed inlet 13 in its wall, and said inlet has connection with a feed supply or inlet conductor 14, whereby the feed material may be introduced into the upper end of the classifier. The overflow material which is separated in said classifier escapes from the upper portion thereof through an axially disposed tube or vortex finder 15 which communicates through an elbow 16 with an overflow discharge conduit 17.

The conical section 12 is normally disposed to direct its reduced end or apex downwardly, and the heavier phase material which is separated in the classifier escapes through the open lower end of said section. Such lower end is formed with an external annular flange 12a, and a discharge control or apex valve 18 is mounted adjacent to said flange, said apex valve being secured in position between the flange 12a and a similar flange 19a provided on the upper end of the tubular discharge nozzle or tailpipe 19. Suitable bolts 20 extend between the flanges 12a and 19a to mount the apex valve 18 in position.

The discharge control or apex valve 18 has a variable bore or opening 21 extending therethrough, and such opening functions as a variable discharge orifice for the underflow, i.e., the material discharging from the lower end of the classifier. As is well known, the cyclone classifier is usually disposed with its apex directed down- Wardly, but said classifier may be operated with its axis in other than a vertical plane. However, for the purposes of the present description the material discharging from the apex will be referred to as the underflow and it is to 'be understood that such term shall include such discharging material irrespective of the particular disposition of the classifier.

The valve 18 may take any of several physical forms but, as illustrated, one form of said valve includes an annular resilient or flexible tube-like element 22, the interior of which is connected with a pressure fluid line 23. Variation of pressure within the interior of the element 22 will expand or contract said element to vary the size of the bore or opening 21 through said element and thereby vary the size of the underflow discharge orifice of the classifier. As is well known, variation of the size of said discharge orifice will change the con figuration or pattern 24 of the material discharging from said classifier.

In the operation of the cyclone classifier 10, the feed stock enters the upper cylindrical section 11 through the inlet conductor 1'4 and the tangential feed inlet 13 and is subjected in the usual manner to a whirling centrifugal action within the sections 11 and 12. The heavier phases of the material are thrown outwardly toward the walls of the conical section 12 where said heavier materials collect and pass downwardly through the underflow discharge orifice 21 of the apex valve 18 and then outwardly through the tailpipe 19. The finer, less coarse materials move toward the center of the cyclone and are drawn into the vortex finder 15 and pass therethrough into the elbow 1 6 and the overflow discharge conduit 17.

As noted above, the configuration or pattern 24 of the underflow is directly related to the operating efficiency of the cyclone and is thus indicative of the effectiveness of the separation occurring within the cyclone. The angle A described by the lines 24a and 241) represents or defines the preferred range or area within which the outer surface of the underflow is to be maintained for maximum efficiency and optimum separation. As will more fully appear hereinafter, when the outer surface of the underflow is not within this range the cyclone is not operating at maximum efficiency, and the desired separation or classification of the feed is not being obtained; and it becomes desirable to make certain operating changes or corrections which will insure operation of the cyclone at maximum efficiency.

When the cyclone is operated under underload conditions, the outer surface of the underflow extends beyond or outwardly of the preferred outer limit line 24b. Under these conditions, too much of the feed passes through the underflow discharge opening 21, and the desired degree of separation does not occur. Thus, particles of the desired size to be separated pass out of the cyclone in the underflow rather than through the overflow discharge elbow 16.

Under overload conditions, the outer surface of the underflow is within or centrally of the preferred inner limit line 24a. Under these conditions, the underflow is generally said to be ropy, as indicated by the dotted lines 25 and 26 in FIGURE 1. When the underflow pattern has this ropy configuration, undesirable coarse materials are carried over through the overflow discharge elbow 16, and the cyclone may become inoperative due to plugging.

As is well known, underload conditions may occur for several reasons. For example, when the quantity of feed stock introduced into the cyclone classifier through feed inlet nozzle 13 is less than that quantity at which optimum separation of particles and maximum efficiency are obtained, or when the underflow discharge opening 21 is too large for a given desirable rate of feed, or when the constituency of the feed, such as the coarseness of the grind, varies appreciably during operation, even though there is no change in feed rate. As noted previously, a flaring wide-angle underflow discharge pattern is indicative of such underload conditions. Conversely, overload conditions may occur when the quantity of feed stock introduced through the feed inlet nozzle 13 is greater than that quantity at which optimum separation of particles and maximum efficiency are obtained or when the underflow discharge orifice 21 is too small or restricted for a given desirable rate of feed or when constituency of the feed changes. Such overload conditions are indicated by a more axial or ropy underflow pattern.

For sensing and ultimately controlling the underflow pattern 24 in order to maintain the outer surface of said underflow pattern within the desired limits 24a and 24b to preclude the foregoing disadvantages, a sensing means is provided.

The sensing means includes an outer sensing element or probe 29 which is suitably supported by an adjustable bracket or other support 291) so as to locate its extremity 29a at the outermost li-mit line 24b of the pattern 24, which is the point at which satisfactory operation is obtained. The sensing means also includes an inner sensing element or probe 30 which is suitably supported by an adjustable support 36b so as to locate its extremity 30a at the innermost limit line 24a of pattern 24 at which satisfactory operation is obtained. The probes are constructed to provide a signal when the material of the underflow is contacting said probes and to provide a different signal when said material is out of contact therewith. Therefore, if the underflow pattern is such that its outermost surface, as indicated by line 24b, moves outwardly of the outer probe 29, the end 29a of said probe is contacted by underflow material and a signal is generated. On the other hand, if the underflow pattern is such that its outermost surface, as represented by line 24a, moves inwardly of the end 3611 of probe 30, no material is contacting probe 30 and a signal is generated. The signals generated by probes 29 and 30 may be readily utilized to indicate that the outer surface of the underflow is not within desired limits.

Although any type of sensing element which will generate a signal upon contact or noncontact with the material may be employed, one type which has been found satisfactory is one which is capable of connection in an electrical circuit, with the circuit being opened and closed by contact or noncontact of material with the element, and the elements 29 and 3!} are of this type. The element 29 has electrical connection through conductor 31 with an electrically-actuated controller 32; a conductor 33 eXtends from the controller and is connected to the metallic tailpipe 19, and with this arrangement the electrical circuit between tailpipe and element 29 is completed by the underflow material. In a similar manner the element 30 has electrical connection through conductor 34 with an electrically-actuated controller 35; a conductor 36' extends from the controller 35 and is connected to the metallic tailpipe 19, the electrical circuit between tailpipe 19 and probe 30 being completed by the underflow material. Thus, it will be seen that an electrical circuit is affected in accordance with the contact or noncontact of underflow material with the sensing probes.

The controller 32 may have electrical connection with an alarm 37 to actuate said alarm when the outer surface of the underflow comes in contact with the probe 29. Also, the controller 35 may be connected with said alarm to operate the same when the outer surface of the underflow moves out of contact with the inner probe 30. When the alarm 37, which may conveniently be a bell or light, is actuated, manual corrections or adjustments of the operating conditions of the cyclone may be accomplished so that the outer surface of the underflow will be brought within the preferred range A, whereupon the alarm 37 will no longer be actuated.

It is preferable that automatic control of the underflow pattern 24 be effected, and in FIGURE 1 is shown an apparatus for varying the size of the underflow discharge orifice 21 so that the outer surface of the underflow may be maintained within the preferred range A.

The outer probe 29 operates in the manner previously discussed, completing the electrical circuit through the controller 32 when the outer surface of the underflow moves out of the preferred range A and comes into contact with the said probe 29. The controller 32, by means of well known electrical circuits, then causes the relay 38 to open the pressure fluid supply valve 39, whereupon the pressure fluid, such as air, may enter the flexible annulus 22 through the conduits 40 and 23. The resulting expansion of the annulus 22 restricts or reduces the size of the underflow discharge orifice 21, and as the size of the orifice 21 is reduced the outer surface of the underflow moves inwardly or axially into the preferred range A, whereupon contact between the outer probe 29 and the underflow is broken. This opens the circuit connecting the probe 29, controller 32 and tailpipe 19, and the controller 32 then operates to close the supply valve 39.

When the outer surface of the underflow moves inside or centrally of the inner limit line 24a and out of the preferred range A, contact between the underflow and the inner probe 30 is broken, thereby opening the electrical circuit of which the controller 35 is a part. In response to theopening of said circuit, the controller 35 operates to open the pressure fluid exhaust valve 41 by any well known means, such as electrical connection with the relay 42. When the exhaust valve 41 is thus opened, the air within the resilient annular valve member 22 escapes therefrom through the conduits 23 and 43. The resulting contraction of the valve member 22 increases the size of the underflow discharge orifice 21, and the outer surface of the underflow moves outwardly into the preferred range A. When the underflow contacts the inner probe 30, the circuit through controller 35 is completed and the exhaust valve 4-1 is closed, thereby trapping the pressure in the valve member 22.

Thus, the size of the underflow discharge orifice 21 is automatically maintained at that size for which the outer surface of the underflow is within the preferred range A. It will be understood that any satisfactory fluid, in addition to air, may be used as the pressure changing means so as to vary the pressure within the flexible annular valve member 22. Furthermore, there are several types of variable underflow discharge orifice valves, such as the disc type, commercially available which may be used eifectively as the apex valve 18.

In the embodiment shown in FIGURE 2, the configuration or pattern 24 of the underflow, being indicative of the operating efilciency of the cyclone, is utilized to automatically vary the input load to the cyclone so that operation at maximum efiiciency will be assured.

In a typical ore-grinding circuit, the ore is discharged from the storage vessel 44 through outlet 45 and onto a conveying means such as the continuous belt conveyor 46. The variable speed control 47 operates to vary the speed of the belt conveyor 46, and, as will be explained, such variation is accomplished automatically in response to a change in the pattern 24 of the underflow. The ore then passes from the conveyor 46 into the grinding mill hopper 43 and thence into the grinding mill 49. The ground ore is discharged from the mill 49 into a hopper 5t) and conducted to a pump 51. The discharge line 51a of the pump 51 is connected to the inlet conduit 14 and inlet nozzle 13 of the cyclone 10. The cyclone 10 then operates in the manner previously discussed, and the proper size finished material carries over through the overflow discharge elbow 16 with the coarser materials being discharged in the underflow. The coarse underflow discharges into a hopper 52 which, in turn, discharges into grinding mill hopper 43 to recycle the material to the grinding mill 49.

The sensing elements or probes 29 and 30 are properly located in relation to the underflow to be contacted by the outer surface of said underflow in the manner discussed previously. When the cyclone is operated under underload conditions, the outer surface of the underflow pattern moves outwardly and, upon reaching the outer limit line 24b, comes into contact with probe 29. The contact between the underflow and the outer probe 29 completes an electrical circuit to an electrical control means 53 by means of electrical leads 54 and 55. The completing or closing of this circuit causes the control means 53 to actuate the variable speed control 47, thereby increasing the speed of the conveyor belt 46. The input load to the cyclone It is thus increased until the outer surface of the underflow pattern moves inwardly into the preferred range A and out of contact with the probe 29, at which time the circuit to the control means 53 is opened. The control means 53, in response to the opening of the aforesaid circuit, is thereby inactivated, and the point to which the control 47 was adjusted is maintained to thereby maintain the speed of the conveyor belt 46.

When the cyclone 10 is overloaded, the outer surface of the underflow pattern moves inwardly out of the preferred range A, and contact between the inner probe 3% and the underflow is broken. This loss of contact opens the electrical circuit formed by the material, the inner probe 39, electrical lead 56, control means 53, electrical lead 55, and the underflow tailpipe 19. The control means 53, in response to the opening of the last mentioned circuit, actuates the variable speed control 47 to decrease the speed of the conveyor belt 46, thereby decreasing the input load to the cyclone 10. As the input load is decreased, the outer surface of the underflow pattern begins to move outwardly and will continue to so move until said outer surface is within the preferred range A and contact is again made with the inner probe 30. The control means 53, in response to the reclosing of the electrical circuit, maintains the variable speed control 47 at its adjusted level to maintain the speed of the conveyor belt 46 at that point.

Thus, the outer surface of the underflow pattern, being indicative of the operating efilciency of the cyclone 10, is automatically maintained within the preferred range A by automatically varying the input load to the cyclone 10 in response to changes in the underflow pattern 24.

From the foregoing, it is apparent that the underflow pattern or configuration 24 is utilized to control the operating conditions of the cyclone 19 so that maximum efficiency and optimum separation are obtained. Although the control of the discharge orifice of the cyclone has been described separately from control of the input load to the cyclone, it is evident that both types of control could be combined, whereby the size of the orifice as well as the volume of feed may be simultaneously adjusted. Also, the alarm or signal can be employed separately or in conjunction with the automatic control systems.

The embodiment of the invention shown in FIGURE 1, wherein the sensing elements 29 and 30 control the pressure to the apex valve 18, lends itself additionally to controlling the volume of cyclone underflow discharge by regulating the feed or input load which is directed to the classifier. For accomplishing this purpose, the pressure which is acting within the flexible annulus 22 of the valvih is utilized to control the speed of the feed conveyor belt 6%, which is shown schematically in FIGURE 1 and which would feed the material to a grinding circuit and ultimately to the classifier 14 in a manner similar to that shown in FIGURE 2. a

It is desirable to maintain the cyclone underflow load within a range between predetermined limits; if the upper load limit is exceeded, which would represent too high a feed rate, the speed of the conveyor belt 60 should be reduced, whereas if the cyclone underflow falls below the lower load limit, the speed of said conveyor belt should be increased.

As has been explained, the apex valve 18 controls the size of the discharge opening 21, and the volume of the material discharging through said opening is a function of the size of the opening which, in turn, is a function of the pressure within the flexible annulus 22. The pressure in said annulus is conducted through a pressure line 61 to an upper load limit pressure-actuated switch 62 and a lower load limit pressure-actuated switch 63. The load limit switches 62 and 63 are associated with a variable speed control 64 which drives the conveyor belt 60 through suitable drive means 65. So long as the pressure in the annulus is within the range defined by the adjustment of the load limit switches 62 and 63, the conveyor belt 60 operates at a predetermined constant speed to maintain a constant input load.

Under overload conditions, the sensing element 30 reacts to reduce the pressure in the annulus 22 in the manner heretofore described. If this pressure reduction is within the range defined by the load limit switches, the speed of the conveyor belt 60 is unchanged. If, however, this pressure reduction is below the predetermined limit, it actuates the upper load limit switch to decrease the input load to maintain the volume of feed to the classifier and thereby maintain the underflow discharge from said classifier within the desired range.

Similarly, under underload conditions the sensing element 29 will function to increase the pressure in the annulus 22, and so long as this pressure is within the predetermined limit the lower load limit switch 63 remains inactive. However, if the pressure in the annulus increases beyond the point for which the lower load limit switch is set, said switch is operated to increase the speed of the conveyor belt 60 to increase the input load to the classifier. The load limit switches, controlled by the pressure in the annulus, thereby control input load to maintain the volume of underflow discharge from the classifier within a desired or predetermined range. It is noted that said switches are in an overriding relationship to the sensing elements, and, while the switches control the range of the underfiow discharge volume, the sensing elements control the discharge pattern within that range.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made within the scope of the appended claims without departing from the spirit of the invention.

We claim:

1. In combination, a cyclone classifier and a sensing apparatus for sensing the position of the outer surface of the substantially conical underllow discharge pattern of the cyclone classifier including, a sensing means located in a position to define a range within which the outer surface of said pattern is to be maintained, and means forming part of the sensing means for generating signals when said outer surface of the pattern is not within the defined range.

2. In combination, a cyclone classifier and a sensing apparatus for sensing the position of the outer surface of the substantially conical underfiow discharge pattern of the cyclone classifier, including, a sensing means located in a position to define a range within which the outer surface of said pattern is to be maintained, means forming part of the sensing means for generating signals when said outer surface of the pattern is not within the defined range, and an indicating means actuated by the signal generating means to indicate the position of the outer surface of the pattern relative to the defined range.

3. In combination, a cyclone classifier and a sensing and controlling apparatus for sensing and controlling the position of the outer surface of the substantially conical underfiow discharge pattern of the cyclone classifier including, a sensing means located in a position to define a range within which the outer surface of said pattern is to be maintained, and means actuated by the sensing means for varying the configuration of the discharge pattern to maintain the outer surface of said pattern within the range defined by said sensing means.

4. A sensing and control apparatus for sensing and controlling the position of the outer surface of the substantially conical underfiow discharge pattern of a cyclone classifier wherein said classifier is provided with a variable underflow discharge opening, said apparatus including, a sensing means located in a position to define the range within which the outer surface of said pattern is to be maintained, and means responsive to the sensing means for varying the size of the discharge opening to thereby control the portion of said outer surface and maintain it within the range defined by said sensing means.

5. A sensing and control apparatus for sensing and controlling the position of the outer surface of the substantially conical underflow discharge pattern of a cyclone classifier including, a sensing means located in a position to define a range within which the outer surface of said pattern is to be maintained, and means responsive to the sensing means for controlling the input load to the classifier to thereby control the position of said outer surface and maintain it within the range defined by said sensing means.

6. In combination, a cycline classifier and an apparatus for controlling the configuration of the substantially conical underfiow discharge of said cyclone classifier, said substantially conical underflow discharge having an outer surface and an axis perpendicular to the base of said substantially conical underflow discharge and extending through the apex of said substantially conical underfiow discharge pattern, said apparatus including, a first sensing means located to be contacted by said underfiow discharge when the outer surface of said underfiow discharge exceeds a preselected angle relative to the axis of the underflow, a second sensing means located to be non-contacted when the outer surface of said underflow discharge falls below a preselected angle relative to the axis of the underfiow, and means responsive to the contact and noncontact of said underfiow with said first and second sensing means for varying the configuration of said underfiow discharge to maintain the pattern within preselected limits.

7. An apparatus for controlling the configuration of the substantially conical underfiow discharge of a cyclone classifier wherein said classifier is provided with a variable underfiow discharge opening, said substantially conical underfiow discharge having an outer surface and an axis perpendicular to the base of the cone and extending through the apex of said cone, said apparatus including, a first sensing means located to be contacted by said underflow discharge when the outer surface of said underfiow discharge exceeds a preselected angle relative to the axis of the underfiow, a second sensing means located to be non-contacted when the outer surface of said underflow discharge falls below a preselected angle relative to the axis of the underflow, and means responsive to the contact and non-contact of said underflow with said first and second sensing means for varying the size of the discharge opening to thereby control the configuration of the underfiow discharge pattern to maintain the pattern within preselected limits.

8. An apparatus for controlling the configuration of the substantially conical underfiow discharge of a cyclone classifier, said substantially conical underfiow discharge having an outer surface and an axis perpendicular to the base of said substantially conical underfiow discharge and extending through the apex of said substantially conical underfiow discharge pattern, said apparatus including, a first sensing means located to be contacted by said underfiow discharge when the outer surface of said underfiow discharge exceeds a preselected angle relative to the axis of the underfiow, a second sensing means located to be non-contacted when the outer surface of said underfiow discharge falls below a preselected angle relative to the axis of the underfiow, and means responsive to the contact and non-contact of said underflow with said first and second sensing means for controlling the input load to the classifier to thereby control the configuration of said underfiow discharge to maintain the pattern within preselected limits.

9. A sensing apparatus for sensing the position of the outer surface of the substantially conical underflow discharge pattern of a cyclone classifier including, a first probe located in a position to define the outermost limit of a preselected range within which the outer surface of said pattern is to be maintained, a second probe located in the path of the material discharging from the classifier in a position to define the innermost limit of said preselected range within which the outer surface of said pattern is to be maintained, a first electrical circuit in which the first probe and discharging material are connected whereby said material completes said first electrical circuit when the material contacts said first probe, a second electrical circuit in which said second probe and discharging material are connected whereby the said material completes the said second circuit when the material contacts said second probe, means actuated by the closing of the said first circuit caused by said material contacting said first probe to generate a signal indicative of the outer surface of the said underflow pattern being outwardly of the outermost limit of the preselected range, and means actuated by the opening of the said second circuit caused by said underflow discharge material moving out of contact with said second probe to generate a signal indicative of the outer surface of the underflow discharge pattern being inwardly of the innermost limit of said preselected range.

10. The sensing apparatus as set forth in claim 9, together with an indicating means actuated by the signal generating means to indicate the position of the outer surface of the underflow discharge pattern relative to the preselected range.

11. A sensing and control apparatus for sensing and controlling the position of the outer surface of the substantially conical underflow discharge pattern of a cyclone classifier wherein said classifier is provided with a variable underflow discharge opening, said apparatus including, a first probe located in a position to define the outermost limit of a preselected range within which the outer surface of said pattern is to be maintained, a second probe located in the path of the material discharging from the classifier in a position to define the innermost limit of said preselected range within which the outer surface of said pattern is to be maintained, a first electrical circuit in which the first probe and discharging material are connected whereby said material completes said first electrical circuit when the material contacts said first probe, a second electrical circuit in which said second probe and discharging material are connected whereby the material completes said second circuit when the material contacts the second probe, means actuated by the closing of the said first circuit caused by said material contacting said first probe to generate a signal indicative of the outer surface of said underflow pattern being outwardly of said outermost limit of the preselected range, means actuated by the opening of the said second circuit caused by said underflow discharge material moving out of contact with said second probe to generate a signal indicative of the outer surface of the underflow discharge pattern being inwardly of said innermost limit of said preselected range, and means responsive to said signal generating means for varying the size of the discharge opening to thereby control the configuration of the pattern and maintain its outer surface within the said preselected range.

12. A sensing and control apparatus for sensing and controlling the position of the outer surface of the substantially conical underflow discharge pattern of a cyclone classifier including, a first probe located in a position to define the outermost limit of a preselected range within which the outer surface of said pattern is to be maintained, a second probe located in the path of the material discharging from the classifier in a position to define the innermost limit of a preselected range within which the outer surface of said pattern is to be maintained, a first electrical circuit in which the first probe and discharging material are connected whereby said material completes said first electrical circuit when the material contacts said first probe, a second electrical circuit in which said second probe and discharging material are connected whereby the said material completes said second circuit when the material contacts said second probe, means actuated by the closing of the said first circuit caused by said material contacting said first probe to generate a signal indicative of the outer surface of said underflow pattern being outwardly of said outermost limit of said preselected range, means actuated by the opening of the said second circuit caused by said underflow discharge material moving out of contact with said second probe to generate a signal indicative of the outer surface of the underflow discharge pattern being inwardly of said innermost limit of said preselected range, and means responsive to said signal generating means for controlling the 10 input load to the classifier to thereby control the configuration of the discharge pattern and maintain its outer surface within the said preselected range.

13. A sensing and control apparatus for sensing and controlling the position of the outer surface of the substantially conical underflow discharge pattern of a cyclone classifier having a discharge opening, said apparatus including, an annular flexible valve element adjacent to said opening and having a bore which forms a discharge orifice for said classifier, means for admitting and releasing pressure fluid to and from the interior of said valve element to change the size of its bore and thereby vary the size of the discharge orifice, a sensing means located in a position to define a range within which the outer surface of said pattern is to be maintained, means forming part of the sensing means for generating signals when said outer surface of the pattern is not within the defined range, and means actuated by said signals to control the admission and release of pressure fluid to and from said valve element to thereby control the size of the discharge orifice to maintain the outer surface of said pattern within the defined range.

14. The sensing and control apparatus as set forth in claim 13, together with a feeding means for conducting material to the classifier, a variable speed actuator for said feeding means, and means for controlling the said variable speed actuator by the pressure in the said flexible valve element.

15. The sensing and control apparatus as set forth in claim 13, together with a feeding means for conducting material to the classifier, a variable speed actuator for said feeding means, and upper load limit means actuated when the pressure in said valve element falls below a predetermined point for operating the variable speed actuator at a decreased speed, and a lower load limit means actuated when the pressure in the valve element exceeds a predetermined point for operating the variable speed actuator at an increased speed.

16. The combination with an ore-grinding circuit having a feed inlet conveyor, a grinding mill, a cyclone classifier having a substantially conical underflow discharge pattern, said substantially conical underflow dis charge pattern having an outer surface, and means for recycling a portion of the ore through said mill, of a control apparatus including, a sensing means located in a position to define a range within which the outer surface of said pattern is to be maintained, and means forming part of the sensing means for generating signals when said outer surface of the pattern is not within the defined range, and means actuated by said signal generating means for varying the speed of the input conveyor to vary the input load through the grinding circuit which varies the load to the classifier to thereby control the configuration of the underflow discharge pattern of the classifier and maintain the outer surface of said underflow discharge within the range defined by said sensing means.

17. A sensing and control apparatus for sensing and controlling the position of the outer surface of the substantially conical underflow discharge pattern of a classifier having a discharge opening, said apparatus including, a variable valve element adjacent to said opening and having a bore which forms a discharge orifice for said classifier, means for admitting and releasing pressure fluid to and from the interior of said valve element to change the size of its bore and thereby vary the size of the discharge orifice, a sensing means located in a position to define a range Within which the outer surface of said pattern is to be maintained, means forming part of the sensing means for generating signals when said outer surface of the pattern is not within the defined range, and means actuated by said signals to control the admission and release of pressure fluid to and from said variable valve element to thereby control the size of the discharge orifice to maintain the outer surface of said pattern within the defined range, a feeding means for conducting material to said classifier, a variable speed actuator for said feeding means, and means for controlling said variable speed actuator by the pressure in said valve element.

18. The combination with an ore-grinding circuit having a feed inlet conveyor, a grinding mill, a cyclone classifier having a discharge opening, and means for recycling a portion of the ore through said mill, of a sensing and control apparatus for sensing and controlling the position of the outer surface of the substantially conical underflow discharge pattern from said classifier, said apparatus including an annular flexible valve element adjacent to said opening and having a bore which forms a discharge orifice for said classifier, means for increasing and decreasing the fluid pressure in the interior of said valve element to change the size of its bore and thereby vary the size of the discharge orifice, a sensing means located in a position to define a range within which the outer surface of said pattern is to be maintained, means forming part of the sensing means for generating signals when said outer surface of the pattern is not within the defined range, means actuated by said signals to increase and decrease the fluid pressure in the valve element to thereby control the volume of the underflow discharge and to maintain the outer surface of the underfiow dis- References Cited in the file of this patent UNITED STATES PATENTS 1,413,934 Ramsey Apr. 25, 1922 1,621,474 Blomfield Mar. 15, 1927 2,506,775 Calabrese May 9, 1950 2,648,433 Wright Aug. 11, 1953 FOREIGN PATENTS 808,914 Great Britain Feb. 11, 1959 OTHER REFERENCES Chemical Engineering, June 1955, Volume 62, Number 25 6, pages 234-238, Wet Cyclones, Tangel and Brison.

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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3179345 *Jul 29, 1963Apr 20, 1965United States Steel CorpMethod and apparatus for controlling a grinding mill
US3358938 *Jul 8, 1965Dec 19, 1967Union Carbide Canada LtdMethod of control of particle size utilizing viscosity
US3397844 *Sep 19, 1962Aug 20, 1968Erie Dev CompanyProduct sizing control in a grinding circuit closed by a separating means
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US3690570 *Aug 10, 1970Sep 12, 1972Kennedy Van Saun CoMethod of and system for controlling grinding mills
US3779469 *Feb 18, 1972Dec 18, 1973Westinghouse Electric CorpControl system and method for a reversed ball mill grinding circuit
US3860804 *Apr 21, 1972Jan 14, 1975Westinghouse Electric CorpControl system and method for ball mill and spiral classifier in closed circuit
US4053113 *Sep 24, 1976Oct 11, 1977Metallgesellschaft AktiengesellschaftDry grinding process for reducing ore to pelletizable particles
US4246576 *Apr 26, 1979Jan 20, 1981Krebs EngineersCyclone monitoring apparatus and method
US4364822 *Jul 1, 1981Dec 21, 1982Rich Jr John WAutogenous heavy medium process and apparatus for separating coal from refuse
US5132024 *Nov 26, 1990Jul 21, 1992MintekMeasurement of radius or diameter of cone shaped discharge
US5248442 *Aug 14, 1991Sep 28, 1993MintekMethod and apparatus for measuring shade of hydrocyclone underflow
US6983850Jun 25, 2003Jan 10, 2006Krebs Engineers CorporationHydrocyclone roping detector and method
EP0160629A2 *Apr 15, 1985Nov 6, 1985WIKDAHL, Nils Anders LennartA method and system for controlling the apex flow of a multihydrocyclone for fiber suspensions
EP0522215A2 *Aug 8, 1991Jan 13, 1993MintekMeasurement method and apparatus for hydrocyclones
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Classifications
U.S. Classification241/34, 209/726, 209/720, 209/548
International ClassificationB04C11/00
Cooperative ClassificationB04C11/00
European ClassificationB04C11/00