US2487845A - Jigging apparatus and method - Google Patents

Description

JIGGING APPARATUS AND METHOD Filed Feb. 21, 1945 CLEAN v CoAL & I 1 CELL %2&QCELL i i i RAW COAL FIRSTJIG CELL CoAL & MIDDLINGS REFUSE SECONDJIG CELL REFUSE (MIDDLINGS) CLEAN CoAL SCREEN A MEDIUM UNDERSIZE SIZE ovEn zsizE A A CRUSHER v )NVE/V 7-0/2 A BYRON M. Basal)s REFUSE C,-

REFUSE I A =ALTERNATE FLOW medium developed is highly important.

Patented Nov. 15, 1949 UNITED STATES PATENT OFFICE V 2,4s7,s45.--

JIGGING APPARATUs METHOD Byron M. Bird, Columbus, Ohio, assignor, by

mesne assignments, to' The Jefirey Manufacturing Company, a corporation of Ohio Application February 21, 1945, Serial No. 579,067

8 Claims. (01.241 20) This invention relates and method.

An object thereof is to provide improved apparatus and an improved method of treating materials such as raw coal to separate the low gravity or clean coal from the high and intermediate gravity refuse, such as shale and bony coal.

Another object of the invention is to provide improved apparatus and methods for carrying out the object above set forth in which a heavy or high specific gravity separating medium is developed and is continuously conditioned as to specific gravity by means of the controlled recirculation of one or more difierent products of high or intermediate gravity material derived by screening or otherwise separating and/ or treating the high gravity product of a compartment other than the firstcompartment of a multiple compartment jig with raw material undergoing treatment in the first compartment of the jig.

In carrying out the foregoing object it is another object of the invention to provide improved material separating apparatus and methods wherein the characteristics of a heavy or high specific gravity separating medium developed from material being separated are controlled by the recirculation of controlled quantities of vari-'- one size ranges of products of high gravity ma terial derived from high gravity material obtained from any but the first compartment of a multiple compartment jig to the first compartment of the jig to be treated with raw material undergoing treatment therein. g

Other objects of the invention will appear hereinafter, the novel features and combinations to a jigging apparatus being set forth in the appended claims;

In the accompanying drawings,

Fig. 1 is a'diagrammatic showing of apparatus involving my invention which is capable of carrying out the methodof my invention; and

Fig. 2 is a flow diagram illustrating my invention.

In any process or method effecting a separation according to specific gravity the density of the That this is the case may be seen from the following consideration: Suppose particles of two specific gravities are to be separated, one kind beingv 1.45

specific gravity and the other 1.50 specific gravity.

In air the specific gravity of one particle is LEO/1.45 or 1.034 times that of the other particle. If these particles are immersed in. water this ratio of specific gravities becomes 1.501/1.45 1=.50/.45 -,1.111,

Itmixed sizes are being separated according to'specific gravity, such as a size range 5" x0", every particle is buoyed up by the surrounding particles. In other. words the surrounding particles form a fiuid specific-gravity medium having an effective density equal to the average specific gravity of the particles and the water taken together. In a jigging process or method, for example, the medium density for separation at 1.45 specific gravity might be as much as 1.40 specific gravity. Under these conditions the ratio of the particles being separated becomes 1;50-1.40/1.451.40=.10/.05=2.0.

Carrying this illustration through three more steps will demonstrate an important phenome non as to the great importance of the last step in increasing the density'of the medium to obtain a'sharp separation ata predetermined specific gravity. Assume the density of the medium is increased from 1.40 to 1.42, the ratio is-1.50. .1.42/1.451.42=.08/.03=2.7. This is only a small increase in ratio over 2.0 obtained from 1.40 specific-gravity medium. If the density of the medium is increased to 1.44, the ratio is 1.50. 1.44/1.451.44=.06/.01:6.0. This is a greater increase, but still not an exceedingly great one. However, if the density is increased by another .01, the ratio reaches infinity for 1.501.45/1.45- 1.45=.05/.0=infinity. Thusthe last .01 increase in density of the medium is of great importance.

In the method or process and apparatus involving my invention a jig or other standard separatingor classifying device is used in which the cost of operation is relatively low and pro,- vision is made for building up the density of the medium to a point where it just equals the specific gravity of the low-gravity particles to. be separated. In other. words, in the illustration above used the desired efiective density ofv the medium would be 1.45 specificgravity.

That such a medium is not developed in the course of normal jigging operation can be readily seen. Suppose coal is being separatedby jigging and thestratification is complete. At a certain level in the jig bed there is a. more or less well defined zone at which a split must be made between the materials that are to fiow over as washed coal and, those that are to be disch arged as refuse. If a separation at this point is very sharp, the particles right at the dividing line aresclose to 1.45 specific gravity. However, since the interstitial spaces between the particles are filled with water, the medium density of the water and particles considered together is inevitably less than 1.45 specific gravitysince the specific gravity of the water is 1. If the density of the medium is to be raised to 1.45 specific gravity, the interstices must be filled with something of higher density than water. This might be a very heavy liquid such as zinc chloride or calcium chloride, for example, but in the method and process involved in this invention this medium is built up wofifine particles,'the specific gravity of which .is above 1.45, which particles are immersed in water.

One apparatus for applying a heavy medium for jigging operation is illustrated in the accompanying drawings. For example, the raw coal being treated may have a size rangeof 3'; x", but it is to be clearly understood that the method or process is applicable to larger sizerange and to any specific-gravity separation. The important point is the return to the jig feed or to the first jigging compartment of small intermediate gravity refuse particlestto form an interstitial mediumbetweenthe larger particles. -As one il lustration,-. these refuse; particles may have a size range;of% ,x=0". For a separation at 1.45 specific. gravity. this medium should be just 1.45 specific gravity. :Under :these circumstances the coarser particles :being separated in the jig are huoyedup byrothen coarseparticles of 1.45 specificrgravityand higher-and by the smaller particlesqofiinterstitiatmedium made up of water and highegravity 'particles, such as bone, which may rangefrom 2.0 to 2.-2-specific gravity.

lThe methodporaprocess here'involved is to be carefully distinguished from that sometimes used in:jigg-ing practice-in the crushing of middlings. In this ;practice the middlings are usually screened and '.the;:fine sizes sent to refuse, only the coarsesizes beingysent' to a .crusher and then back-lto the .jigifeed. ,This is done to avoid a build-upsof 'fine;refuse in thecircuit which is just the oppositefrom what iszhere being done, in Which'the intent is to buildup the medium under. carefully controlled conditions.

In the practical operation of the .apparatus and the consequent carrying. out of the .process and method, the operation and method of applying the heavy mediumzto the jig is .accomplished in a -relatively simple. manner. The jig employed is equipped with automatic control. This in .a large measure maintainsthe. medium in thejig without attention from.thesoperator. However, for best results,- the tonnage should bekept within reason- :ablelimits and thefjig should not be allowed to idlefor prolonged-periods with no feed, for this However, if themel l f-urther l'ielp in maintaining themedium is to select a screen having perforations of such size in the first and-second compartments of the jig.

"if a'thr'ee compartment jig is used, or in the first compartment ofthe jig'if a two compartment'jig is used,- so that the required amount of medium -'is-retained inthe-firsttwocompartments in the case --of a three compartment jig and in the *first compartment in the case of a two compartment jig, rather thanbeing hutched through the screen.

In getting the heavy-medium method-into operation, the last compartment is hutched hard to draw through-the screen all of the fine bone --particlestogether with some fine coal. be done most readily by operating the jig with -a-relatively longstroke-and a minimum of water.

This can The fine bone and the refuse materials of intermediate specific gravities pass up the last elevator and are screened to separate the medium. This, together with such other parts of the last elevator product as desired, is returned to the jig feed. When the medium begins to build up in the circuit, the length of stroke and the amount of Water used inz, the first compartment are regulated-to pass, deliver or.feed together. with the low gravity separation product of the first comapartment a substantial amount of the medium .over.,into.the last compartment, but not more than can be hutched out or drawn through the gejectorrinithat compartment. In this way the presenceofample medium in the first compartment is assured and the last compartment is supplied withhigh specific gravity fluid separating medium from the first compartment which is deliveredthereto with the low gravity material separated in the first compartment. In normal operation the;-last compartment isalways operated to hutch some fine coal. This-is done to assure that no medium is passed over into the washed coal.

With;theabove general description in mind, attention is directed to Figs. 1 and 2of the drawings inwhich. I have. diagrammatically illustrated one form of jig and associated apparatus together=with a flowasheet which teaches my invention. A jig. Ill is providedwhich may be either of the two compartment or three successive compartment type, but inthedrawings I have illustrated a two compartment jig. This jig may take substantially any :desired form, but as one illustrationrof a :general construction thereof, which maybe employed and which: has certain desired characteristics'inrspecific'aspects of my invention, reference ismade-to thepatent to O. R. Strawn, No. 2,281,530, for a.-Jig, dated April 28, 19.42. The jig includes a feed chute H by which the. coal .toibe 'treated is delivered from any desiredxsource-suchas a conveyor or other chute I2. The; rawcoaldelivered tothe chute H flows into the: first'treating or stratifying compartment l3rthrough'the feed opening I35 of jig H] where it. is subjected to:a,stratifying and classifying actionqandzthe refuse'orhigh gravity material is withdrawn. by way: of the. refuse. elevator or conveyor M .with :,the low gravity .material or par- 50 tially cleaned coal being .deliveredto the successive second compartment l5 where it isagain subjected'to. a jigging action to make the final separation of-coal andrefuse. Some middlings or intermediate gravity material will-pass with 55 the coal from the first compartment l3 into the :second compartment I 5.

In case-a three compartment jig is employed there will, oflcourse, be a third compartment which .will effect thefinal separation, the first 60 two compartments in that case being substantially identical in construction and performing the preliminary and intermediate: treatments, re-

spectively. The clean coal from the last com- :partment l.5.is delivered along one path by way 65 of cleancoal chute .lfiand the intermediategravity product from the last compartment is removed and elevated by. elevator ll which has a greater height than elevator or conveyor I4, as

hereinafter .described. The refuse removed in .thefirst. compartment and delivered to the refuse elevator:or conveyor :l4.fiowstherefrom by way of a chute [8 to a refuse receptacle or pile. The product from the second elevator IT or at least 'a-portion thereofisdeliveredfor treatment to a '76 screen l9 which is preferably-adouble deck reciprocating screen beingprovided with a vibrat ing or reciprocating mechanism and spaced upper and lower screen cloths 2I and 22,. respectively.

The use of a double deck screen is very desirable in the most complete aspect of my invention because it has been found very effective to remove intermediate size bony coal, which otherwise might build up in excessive amounts. This will be explained completely hereinafter.

In certain broader aspects of my invention it is to be understood that a single deck screen I9 may be employed. With a double deck screen I9 it is obvious that three size ranges of refuse will be produced thereby. The fines will pass through both the screen cloths 2I and 22 and be delivered by bottom chute 23 to a longitudinally extending screw conveyor 24 by which said fine sizes of refuse or intermediate gravity material will be conveyed forwardly. The intermediate size material which passes only through the large mesh screen cloth 2I and cannot pass through the small mesh screen cloth 22 is delivered to a bifurcated chute 25 which feeds into the previously described refuse chute I8 and is delivered to the refuse receptacle or pile, previously mentioned, or to conveyor 24, depending on the position of a control valve 3 I. The reason for this selective alternative fiow is explained later: :This :intermediate size product will be largely true bone, i. e., finely disseminated coal and shale. The oversize material from the screen I9 will flow by way of chute 25 for treatment in a crusher or grinder 2'! which reduces it in size to liberate coal from refuse and normally delivers it to the screw conveyor 24, where this fine product together with refuse in the conveyor 24 derived from the fines of screen I9 will be conveyed forwardly and delivered to the feed chute II of the jig II]. It is to' be understood that all or part of the intermediate size from the screen may be selectively recirculated either alone or with all or part of the fines from screen I9. To this end I may employ a bleeder chute 29 provided with a control valve 30 in connection with the conveyor 24 and similar bleeding devices may be provided individually to the crusher 2? and the chute 23 for selectively bleeding them, if desired. Bleeder chute 29 and valve 30 co-operate to form a control means for controlling the return of the small size screened material or the products passing through screen 2I and they may be operated in conjunction with other control means hereinafter described for selectively controlling the return of these materials to the feed chute II and consequently to the first jigging compartment I3 of jig III.

In certain broader aspects of the invention the grinder 21 may be eliminated entirely and the fines of screen I9 alone relied upon. In this case the screen I9 will probably be a single deck screen. The double deck screen is particularly effective to remove the intermediate size bone because of the following efiects: Material particles formed in part of pure coal and part of bony coal of relatively large size will normally appear as refuse in the draw of second compartment I5 and thus be delivered to the screen I9'by elevator I1. These relatively large particles will be delivered to the grinder 21 and when crushed will liberate the pure coal from the bony coal. As a consequence, as this reduced material passes through the jig the second time, the liberated clean coal will pass over the final clean coal chute I6 and the bone coal will again reappear in the elevator IT. This time some of the bony coal which has. been freed of the pure coal will be of intermediate.

size and will pass through the' coarse screen H, but such of :it as is coarser than screen 22 will be delivered to the chute 25 and. to the refuse receptacle or pile. However, some of this inter-:

mediate size may, under certain circumstances,

be selectively recycled, a point that will now be- For instance, considerable water may be used incombination with a relatively short stroke. This type of stroke gives a separation according to size as well as according to specific gravity, as in a hydraulic classifier, for example. Such a method of operation would wash the medium out of the interstices and so cannot be used. A stroke must be used thatwill avoid this classifying action. Such a stroke comprises (1) a sharp initial upward acceleration of the water, (2) a short period at approximately uniform velocity, and (3) a downward movement of the water. During the first or upward phase, the bed is lifted in a mass. During the second, the particles become completely mobile so that they are free'to separate. During the third or downward phase, they are separated according to specific gravity.

If this type of stroke isto be applied effectively, I have found that the screen analyses of the jig feed should be controlled to assure a reasonable percentage of intermediate sizes. For instance, in a jig feed 3" x 0", this means a reason-' able percentage of 2" x1" sizes. These intermediate sizes, by locking against each other on the up stroke and during the period of opening of the bed, assist greatly in retaining a heavy medium in the jig bed. Thus, if there is a deficiency of intermediate sizes, this may be offset by selectively recirculating some intermediate sizes from the double-deck screen. Although the type of stroke just described has been found to give the most satisfactory results in applying the heavy medium, it is not essential to my invention in certain broader aspects thereof. The prime requisite is a method of operation that will keep the. medium in the interstices between the larger particles. This requirement is, of course, fundamental.

To provide for the selective recirculation or discharge, that is, the control of the return of intermediate size products of screen I9 to chute II and compartment I3, bifurcated chute 25 is a 'bleeder chute having two legs, one leading to chute I8, the other to conveyor 24. 'Valve 3| co-operating with the legs of bifurcated chute 25 forms a control meansgthat'controls the flow' of said products to chute I8 or conveyor 24 or a division thereof between them.

Although the intermediate size product is sometimes recycled in the manner above described, the normal procedure is to send it to final refuse. Therefore, it is to be distinctly understood that .the method of and apparatus for removing the intermediate size bone or finely disseminated coal and shale is an important step in the process or method of my invention and the apparatus for doing it is an important part of the apparatus invention. 1

' It is further to be understood that while I have sometimes referred to the recirculated-fine materialas high. gravity material, it is only relative'ly h gravity materia and'is generally rezferred' to. as intermediate gravity material, as it is largely material of specific gravity of 2.0 to 2.2 and this will be represented largely by fine bony coal rather than fine shale. It is, of course, evident that the shale, both large and fine, will be removed very largely in the first compartment I3 and will be discharged as refuse by the elevator l4 and chute I8, so it is actually intermediate gravity fines which are employed as a socalled heavy gravity medium. In an installation in which a three compartment jig is employed the refuse which is screened and/or crushed as above described is preferably that derived from the third compartment and the first and second compartment have their refuse discharged to the refuse pile. It is to be understood, however, that in certain broader aspects of the invention, in such a situation the refuse from the second and/or the second and third compartments may be screened and/or crushed and all or desired quantities thereof may be selectively recirculated to control concomitantly the specific gravity of and the ratio or relative quantities of pieces of high gravity material of different size ranges in the high gravity medium developed from the material being separated.

In the specific illustration of my invention, above described, the separation of refuse from coal was used. It is to be understood, however, that it is not limited to the cleaning of coal, but may be used to separate substantially any granular materials of different specific gravities, of which the treatment of iron ore to separate the concentrate from the gangue is another illustration.

From the foregoing it will be obvious that I have provided improved apparatus and methods for separating mixed granular materials of different specific gravities according to their specific gravities in a plurality of successive treatments in separate fluid separating media, the effective density of which is controlled by the amount of high gravity material therein derived from material being separated, and that I have provided apparatus and methods for maintaining the effective density of the separating medium at a desired specific gravity by the treatment of adequate quantities of high gravity material separated in one of the successive treatment compartments to produce or obtain therefrom fine high gravity material, adequate quantities of which are returned under control to the separating medium for maintaining the effective density of the separating medium in the treating compartments at a desired specific gravity.

Obviously those skilled in the art may make various changes in the details and arrangement of parts Without departing from the spirit and scope of the invention as defined by the claims hereto appended and I wish therefore not to be restricted to the precise construction herein disclosed.

Having thus described and shown an embodiment of my invention, what I desire to secure by Letters Patent of the United States is:

1. Separating apparatus of the type wherein a high gravity separating medium is developed from materials being separated and the ratio of different size range constituents in the high gravity separating medium and the specific gravity of the latter may be controlled, the apparatus including a gravity separator having a plurality of compartments for successively treating material to separate it according to specific gravity, means for removing the high gravity material constituent from said first compartment, means for removing the high gravity material constituent from a succeeding compartment, means for screening said last mentioned high gravity material into products of three different size partments for controlling the ratio of said' screened and crushed material in the high gravity medium and the specific gravity of the latter;

2. The method of controlling the specific gravity of a high gravity separating medium obtained from materials being separated while separating the materials by jigging into constituents of different specific gravities therein, the method including the successive stratification of a bed of materials of different specific gravities by jigging in said high gravity medium in a plurality of separate jigging treatments, directing the stratified materials in each treatment along difierent paths including delivering the low gravity material from the first treatment for the successive stratifying treatment, and returning a fine intermediate gravity material derived from the second treatment to be treated with raw material undergoing the first treatment, said returned fine intermediate gravity material being produced at least in part by reducing large intermediate gravity material derived from said second treatment and at least in part by fine intermediate gravity material derived directly and without reduction from said second treatment.

3. The method of controlling the specific gravity of a high gravity separating medium obtained from materials being separated while separating the materials by jigging into constituents of different specific gravities therein, the method including the successive stratification of a bed of materials of different specific gravities by jigging in said high gravity medium in a plurality of separate jigging treatments, directing the stratified materials in. each treatment along different paths including delivering the low gravity material from the first treatment for the successive stratifying treatment, and returning a fine intermediate gravity material derived from the second treatment to be treated with raw material undergoing the first treatment, said fine intermediate gravity material including fine intermediate gravity material derived directly and without reduction from said second treatment.

4. The method of controlling the specific gravity of a high gravity separating medium obtained from materials being separated While separating the materials by jigging into constituents of different specific gravities therein, the method including the successive stratification of a bed of materials of difierent specific gravities in said high gravity separating medium in a plurality of separate jigging treatments, directing the stratified materials in each treatment along different paths including delivering the low gravity material from the first treatment for the successive stratifying treatment, separating intermediate gravity material derived from said second treatment into three different size ranges crushing at least part of the largest size range material derived by said separation, and returning at least part of the said crushed material and at least part of the smallest size range material derived by said separation to the first treatment to be concomitantly treated with raw material undergoing the first treatment and, for controll- 9 ing the specific gravity of the high gravity separating medium.

5. The method of maintaining a high specific gravity separating medium obtained from materials being separated by jigging at a desired specific gravity while separating the materials by jigging into constituents of difierent specific gravities, the method including the successive Stratification by jigging of a bed of materials of diflerent specific gravities in said high gravity medium in a plurality of separate jigging stratifying treatments, directing the stratified materials in each treatment along different paths including delivering the low gravity material from the first treatment to a successive jigging stratifying treatment, treating intermediate gravity material separated in a successive stratifying treatment to obtain fine intermediate gravity material, and returning said treated fine intermediate gravity material to said first stratifying treatment for maintaining said high specific gravity separating medium at a desired specific gravity.

6. Apparatus for separating granular materials of difierent specific gravities according to specific gravities by successive Separations in a high specific gravity fluid separating medium including a first separating compartment, a successive separating compartment, jigging means for applying a jigging action to the materials in said compartments to stratify said materials, said compartments being adapted to contain high gravity fluid separating medium which is maintained in suspension by said jigging means and the density of which is controlled by the percentage of fine intermediate gravity particles therein derived from material being separated, means for feeding mixed granular material to said first separating compartment, means including said jigging means for separating said mixed materials therein according to specific gravities,-

means directing the high gravity materials separated in said first compartment along one path, means feeding low gravity materials separated in said first compartment to a successive compartment for separation according to specific gravities therein, means delivering the low gravity product of said successive compartment along one path, means for treating intermediate gravity material separated in said successive compartment to produce fine intermediate gravity material therefrom, and means for returning said treated fine intermediate gravity material to the separating medium in at least one of said compartments for maintaining the specific gravity thereof at a desired value.

7. Apparatus for separating granular materials of difierent specific gravities according to specific gravities by successive separations in a high specific gravity fluid separating medium including first and successive separating compartments adapted to contain high gravity fluid separating medium the density of which is controlled by the percentage of fine intermediate gravity particles therein derived from material being separated, jigging means for applying jigging action to the materials in said compartments to stratify said materials and to maintain said high gravity medium particles in suspension, means for feeding mixed granular material to said first separating compartment, means including said jigging means for separating said mixed materials therein according to specific gravities, means directing the high gravity materials separated in said first compartment along one path, means feeding low gravity materials separated in said first compartment to a successive compartment for treatment therein, means delivering the low gravity product of said successive compartment along one path, means including a grinder for treating high gravity material separated in said successive compartment to produce fine intermediate gravity material therefrom, and means for returning said treated fine intermediate gravity material to the separating medium in said compartments for maintaining the specific gravity of said intermediate specific gravity fluid separating medium at a desired value.

8. Apparatus for separating granular materials of different specific gravities according to specific gravities by successive separations in a high specific gravity fluid separating medium including a first separating compartment, a successive separating compartment, said compartments being adapted to contain a high gravity fluid separating medium the density of which is controlled by the percentage of fine intermediate gravity particles therein derived from material being separated, jigging means for applying jigging action to the materials in said compartments to stratify said materials and to maintain said high gravity medium particles in suspension, means for feeding mixed granular material to said first separating compartment, means including said jigging means for separating the mixed materials therein according to specific gravities, means directing the high gravity materials separated in said first compartment along one path, means feeding low gravity materials separated in said first compartment to said successive compartment for treatment therein together with substantial quantities of high specific gravity separating medium for supplying said successive compartment with separating medium, means delivering the low gravity product of said successive compartment along one path, means including a screen for treating intermediate gravity material separated in said successive compartment to produce fine high gravity material therefrom, and means for returning said fine intermediate gravity material to the separating medium in said compartments for maintaining the specific gravity of said high specific gravity fluid separating medium at a desired value.

BYRON M, BIRD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date ,224,138 Chance May 1, 1917 1,392,401 Chance Oct. 4, 1921 1,451,067 Elder Apr. 10, 1923 1,656,27 Downs Jan. 17, 1928 1,685,521 Chance Sept. 28, 1928 1,710,568 Carl Apr; 23, 1929 2,052,004 Remick Aug, 25, 1936 2,151,175 Wuensch Mar. 21, 1939 2,194,139 Davis Mar. 19, 1940 2,217,286 McNally, Oct. 4, 1940 2,281,530 Strawn Apr. 28, 1942 2,353, 52 Erck July 11, 1944 2,368,416 Holt Jan. 30, 1945 2,378,356 Erck June 12, 1945 FOREIGN PATENTS Number Country Date 224,447 Great Britain Nov, 13, 1924

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