US1996771A - Method and apparatus for placer mining - Google Patents

Description

April 9, 1935. e. A. MACREADY METHOD AND APPARATUS FOR PLACER MINING Filed 001;. 11, 1933 3 Sheets-Sheet 1 April 9, 1935. G. A. MACREADY 7 METHOD AND APPARATUS FOR PLACER MINING 5 Sheets-Sheet 2 Filed Oct. 11, 1933 April 9, 1935. a. A. MACREADY METHOD AND APPARATUS FOR PLACER MINING 3 Sheets-Sheet 3 Filed Obt. 11, 1953 Patented Apr. 9, 1935' "METHOD ANDIAP PARATUS FOR P I JACERj "x M :17 i v .1.

a Ge e -c i re a Losl-Angeles, cam,

- Application Octoberll, 19:33,"Serial No, 693;2l0f i, p 9:Cl aims.&. (o1. 262+2 fl= it My invention relates to a method and apl a ratus for mining shallow ores in open excavae tions, extracting thevaluable portion therefrom, f and disposing of the tailings or rejected portionk; My invention is particularly adapted to the 'working of 'low gradeplacer gold depositsffor 7 ing and merly worked byhydraulic 'mining, to the 'dry;

placer goldgravels'of arid regions, totin' and platinum gravelscand to other deposits in which the volu'rne of tailings greatly exceeds the volume? of values extracted.

Ar -object ofmy invention a method-of min;- f

treating ore .orgravel in such a way 1 v tailingsarejeconomically disposedof" by depositing them in a 'pile or heap and using the deposited tailings as a foundation for, a

that

treating plantover which said plant maybe advanced bodily as the tailing pile is extendedtq follow the working face of the ore or gravel,

I An object: of my invention is "amethod of dis? posing of tailings without the expensejo f transporting-them to a dump after treatment;, To accomplish this I dischargethe tailingsfdirectly from 'a treatment plant onto the flank of a tail ing pile to extend the pile and advance the plant,

' bodily over the surface of the pileto; follow the extension of the pile, using the tailing pile as. the ioundation for supporting the plant.

"Objectsof my invention are a method and an apparatus for economically placer ore, extracting values therefrom, and disposing of the tailings.

An object of my invention-is an apparatus for;

open out or placer mining consisting of adrag line excavator and a bodily movable unit ii'i'- eluding a platform carrying a mast from-which the excavator is operated and a' separatorftof extract values from ore and rejecttailings over" the side of the platform.

'An object of my invention is'a methodand 7 large proportion .of

againj V r An-object of my invention is a method and'ap-- paratus for treating clayey gold gravelsf by screening the fine clay particles from thesand and treating each separately-to recover goldi It is well known that clay has a habitat picking up i gold from sluices and interfering with good' re-V In the treatment of gold placer gravel the pro-: portion of valuable product (gold).v is extremely small in comparison to the rejected worthless ma--" 5 terial (tailings) For example, gravel contain n for gold it isnecessary 'the injunction.

' apparatus by which'valuable mineral is'w ashed; vfrom a gravel ore by water treatment; and a the water salvaged for use dredge usually prohibits dredgingfl r l a v Throughout the mining'districts of Caliiornia,

ten cents gold cubic yard contains only one part oif'golfd to about "100,000,000 parts offwor'th-V less material (by volume) 'conditum,.introduces'ca factor into mining'placer gold that isf often overlooked with disastrous results: namely,-

theeconomical disposal of enormous quantities] a of worthless tailings;

'I'he n ost important problem peculiartothe' mining of low grade goldjplacergravel's is: eco t riomical disposal of a large (:11iari titiesgofivs rorthlessm tailings, a,

This "problem does not trouble gravel mining v for road or structural material becausethe ma trial 'mined' is a marketable product p disposed" of; by salesa Neither does, it ,.tri: uble the undergroundininer because; only higher grade rocx p can be profitably minedi u'nderground and fpthe proportiomof-A tailings tovalues is less' ffl But.init;he mining Iofelowi grade placer fgravels rjtofhandl'e and diS'pOSeof j an extremely large yardage "or worthless {tailing material ata lowic'ost in ,order toshowaprofit; For xam m yqram e ri iniiigfcouldpdig orie very cheaply j'largeduantities'; couldfextract thev gold cheaply; :but was unable jtofsurvivebecause 25 of inabilityato dispose of tailings when enjoined by. courtslinr 1884 against dllj ipirig t aili ngsi into 7 navigable. riverslf Hydraulic mining, which had t been a: flourishing ,.industry in California before 1884. practically ceased a. 'few' ears; after;

Gold dredging, ii Y vhaa'agigr a ts be n; successful largely because the ,disposal of tailings' was solved by'stacking them in the 'rearofgthe-l in wh h ;r 1s f ats+ l e in eilones nomi w mm;a r ds b ing-te dredge floats onwater near the top of the tail;,--- l ingpileandthe stacker is not ;called on to lift an excessive height. In arid regions ther'difiiculty in maintaining a pond in which to float 2.

Arizona and 'other regions" there still remain errori l mous'deposits' of lowj-"grade gold placer gravel unsuitable for dredgingi or hydraulic mining 5t; which await the deve1oprnent-pff=aneconomical V e 'method for mining and treating: This par ticularly true of large grav el depositsfformerly hv a pked in, th "(Sierra N vada, mounta andiof deposits in dry desert regions where corif ditions are notlsu'itable for maintaining a dredge pond; or; wherelhydraulic minin isl prohibited.

' Ap 'm QP QK JP QVidG$ a et i n apparatus' suitable for economicalhandling 55 1.

receptacle l2 up toward sheave I 6 until it'asisomer its load is hauled along trackcable l by cable' 2 I operated from the'thir'ddrum 9' of-the same hoist. 'The hoist 5'is illustrated 'ontop of gravel bank G near its edge and consists of three; cable drums or reels 5, I and 9 driven through clutches;

by motor I Q. The clutches and brakes of each drumcan be operated by control leverssuch as n 1 Levelinguis aidedby having conveyors M and 42'.

at Ill r The form of dumping bucket D illustrated in Figure 1 consists of a receptacle I2 hung by pivoti Hi froma carrier frame l3 which in turn is mounted'on roller sheaves or---wheels l5 to roll along track cable I-. (A third sheave wheel I6 is mounted on the carrier l3 and cable '2' passes thereover. When'bucket D is hoisted clear of the ground by tightening cable l'to position I and ishauled along track cable l'the-load receptacle I 2 takes a position illustratedat D in which the bucket is suspended from pivot H1-with-therear end 'hangingbelow the-mouth: The end of cable I ismadefast to sheave l'l atthe rap er mast 3 and cable 2 passes through sheave I'I; -When over sheaves l6 and II to draw the rearend of sumes a position as atD" with therear end elevated to dump the load.'-' When the load "has been dumped the bucket is hauled back-along track cable I by reelingin cable 4 and c'able' l'is slackened to lower the bucketto the gravelbank' for another load. i a

Treatment plant P is-mounte'd on abodily movf able floor or frame consisting of skids l8 on which may be cross timbers IQ for stiffness and the floor planking 20. The floor is supported on the top ofthe tailing fpileasa foundation and can be moved bodily'by skiddingoron rollersso that it is kept close enough to the advancing edge of the tailing pile in order that the tailingsmay be discharged Onto the slope or fiank'of the tail-' ing pile.

The form of mast or boom 3 consists of two upright posts 36 having a cap cross piece 31' sup-1} porting sheave l1. The mast is held steadyibyguy lines 38' and diagonal Ore dumped frombucket D falls on a grizzly 2 I which allows the moderate size particles of ore to fall through into hopper 22 and rejects the oversize bouldersdown chute to the bc' ttomo'ffthe tailing pile] Oreor gravel in hop'per' 22-pass'es: through gate doors and screw feeders'23 so that a moderately uniform rate (of feed is" deliveredto a revolving screen or tromfnel 24. "Screening pile to become a. partbf the tailing pile.

Fines and water passing through trommel perforations go to-gold1saving S1uices"25. "The sluices are of types common to dredges and placermining in general and consist of inclined'sluices having riiiles on their floors for'trapping gold or other heavymineral product. The sluices are cleaned up periodically to obtain the values.

The sluic'esl discharge onto dewatering sc 'reer 1s 26 which allow water and fine mud to- 'dr'op' through into vats 21 and 29 and passthe grit and sand oversize onto conveyor belts 4i and 42.

7 motor: :32 Io'r' by braces 39 so that it is fast to the floor. l r

method isillustrated by The conveyor transportthe sand out over the slope of the tailing pile and drop it into sub ni1es"43 and H to form the upper'portionof' the main tailing-pile T.- The top surface of the pile:

can be kept level byoccassional strokes of -a hand shovelso that the finished tailin'g dumpwillhave a'smooth surface of -'the'finematerial.

projeetjunequal distances. r a v i The'heaviest portion of the mud settlesto the bottom of vats: 2T and 29 r from which it can be discharged i continuously or atintervals through valves or outlets '45. Partially cleared water overflows into central vat 28, where additional mud :settles and is drawn off through outletl lii; l The clearest 'water in' the topof vat 28 isdrawn pumped into the sluices for use' inj the process again. Additional" clear water must of course be supplied to'make-up' for that-drawn ofifrom the bottoms of the vats and for water clinging to'the 'tailingsx Themud'andiwat'er drawn'oif; from settlingivats: can: be into; settling ponds or .7

feederand conveyor can be suppliedby shafts and belting from a single gasoline or electric individual electric motors wherever required;

1Grizz1y- 2l and chute 33'are supported on a 34 and1conveyors4| and 42 are suspendedz'from piece. Iv

I-loist 5 and lant .P can be anchored against or dead men; Later'al shifting is doneby wrapping a'rope52- around acathadfl and pulling on a'cable suchas 5 L f V I I {There is considerable-option in-the direction at cross piece on braces'39 anda cross piecej48-rest-" ing on angle braces-4 9. The outer ends of "chute shifting by cables'50and 5| attached tostiunpsii -which operations can? be carried. The plant P l and tailing pile-can be moved directly toward hoist5 to'jcutand fill a -narrow trench'. 'If-the' deposit is wideit is to zig zag across a wide cut as illustrated. in Figure 2 whereprevious posi tions of plant? and hoist 5'we're at? and. 5; If

the'deposits are high benches along a gulch or valley thev tailing pilecan be deposited as a strip parallel: to the gulch and the drag line operatedat right angles to the pile to bring down-ma: terial from the hi111sideS;'-" For mining uneven or sloping ground the treatment plant can be provided with sills of unequal or. tapered thickness' so that-the floor and vats can bemaintained level one. tailing pile having '3 a sloping-uppersurface; It is therefore evident I r that ,applicants -method adaptable to areas I which are too rough for a floatingdredge. I f A modified form 'of apparatus embodying the same principles for carrying out-applicant's Figures 536 andi; de

scribed as-follows:

'-'I'he digging element D jconsistsf bf a bucket} i 0 I such a's 'thel conventional Page or Sauermann types" operated by" two cable's- IUZ and H13 from-drums lfli and'illl respectively oni 'shaft I; The drums are driven byianbleetricmotor" ll 0% and; are controlled" brakes and 'clutchesif operatedby levers at l-ll where the operatorhas V aclear'*1v"iew"offthe eitc'avatiofifsluices and? screens. The bucket Ifll-gathers a' load of gravel when dragged against rbank. G by cableylfl;

I Cable IE3 is next reeledin hoisting'the bucket IIH to the topof mast. I I3, cable I02 bein'g kept'tight; while paying? outbybrake or clutch so as to suspend the bucket above the-ground. CablefjIflZ? isslackedoff: completely when the bucket. reaches the top of the mast which;in-turn-slacksdump:

. cable IM to drop the forward 'endof bucket wl,

and discharge itsload. 1

The load is dumped...onto. s hee t I I.5 and grizzly. 'I I6. ,Jets of water. suppliedtbygan electrically.

" driven centrifugal pumpz I I]; through nozzle I I8;

' sprays on the gravelto dishitegratei itgand. wash:

the fines through thegrizzlyiI-J S: and the oversize to chute IZadownWhichbouldersfaretdischargeda 'to tailin'g pile T..;..Fi nes.- drop: throughv to finer;

mesh screens, 1212,1122; I-ZSLWhich; separate the material into;gradedjgsizes,1, each to :be. treated I separately iorrecoveryof gold gorrother valuables:

' The number of screens and coarseness of each:

grade should {be selected. to. suit, thetgravel 'orl Sore of-each :individuallnfline. scheme 51s "as; follows:

-A. typical gradingiz The first grizzly I I5 discharges i larger. than Q 1 inch pieces toi'tailings; 5 The second, screen I2I:;-

discharges 1- to 3-inch material tea-nu et trap or jig 124 Where large nuggets maynbecaptured; Third screen IiZ discharges th to 11-inch ma-;.

terial. to launder; I-and ,thence to one set of sluices I 21. Fourth screen.v I23dischargesl/fiflth'.

to th inch. material to launder 126' andpthence,

; to another. grQup of sluicesj I28; Fines Lsmallen; than l/fiilthinch passing through screen I 23 dropi onto an amalgamated plate .129 and thenceover ,Water supplied byelectricall ydriven centriiuj-g alzp mp H9I.to.laun ders 'I.25...a.ndi; I26 washes;

. the material into distributors I85 and I0] which 1 feedsluices through individual;doors or outlets similar to thestandard practicejofyfloating' gold.

' dredges. ,Sluices} J 21 andjaj 2.81 are equipped with-J ter toidrop throughfrinto;vatsv I33. andiglfl and the conventional-rifles;commonly used on;float.

ing dredges .for recovery ofgpld. and. discharge to: dewatering screens; I3 I and IBZ :whi'ch..allow ;wa-..-

discharge thesandandiggravelonto conveyors" The pulp I and 136 whichextend-zoverthe' slope of -theg tailing pile {and dischargertheflsolids ontothe p leT- passing through screen I23 (the last grading screenL dropsgonto amalgamated plate ,l-za here .the line ancinour. gold reacts with; the

amalgam and sticks. OverfioWing 'pulp passes. over a short section, of -riffles or;an1algam:.traps- I30 to prevent loss of goldoramalgam which may? accidentally have dislodgedg; from iplate. I29 *and; discharges into :vatliijl; -;Grit ahd, ,heavy;mu'd;

settle in vat; I3-I::al dfare 1dischargedlperiodi cally; or continuously by a QSLICtl'OIl DHmIJ' -LOI'J- bodily across the topof tailing pile .8I6;on which through valve .I38 ;;;.Iluid :from the-top of-yat I3! overflows into"vat I39 where additional mud settles and, may bewithdrawn tln1'0uglr outlet) M t r by su on umn. Nat-I39 overflows-mare ly clear', .watelpinto .sma vat I 40; which is the; suctionvat for pump; Igl. l Glear water' from. a;

' t s p y shqu yil era sl lte rat; .4 t mw,

. pe q w t .)wit ii awr ;w. he udlost clinging. toz oyersize. so ,tthatv water can be 75.

cont uous pnlied..-to-thesr z.z1y by; p mp-l The m d a rofith o shou -2 an may; berun to waste or: if; in a'desert, region iverted ta s t g pndst salvagewater.

, In order to give maximum capacitythe screens} H I I, me d zlm 'b -s n ed b t v rups from framepiece; I59 so that th y maybe iven asshakingniotion, Pitmen I43 and. M4:

driven by electric motor I45 are provided for shaking the screens and also-jig or nugget trap J24. Conveyorsshown are operated by electric motors as self contained units and the-dewater ing screens may also be 'provided-with'rnotorsto ive vibration forincreased capacity. Auxiliary pump; I 53 nay. also; be provided together" with a length oi flexiblej. hpscalfqr miscellaneous. use ineluding pumpingheavymud from vats, I

Electric motors ;,are illustrated; with this form but where electric. power is. not, available. steam or. internal combustionmotors can beused, -I: A. cross piece .146 supported by angle braces I41 and frame piece .159 provided a sfupportout over the slope ,of-ithe; tailing pi e from which the outer ends, ofi chutes 'and conveyors may be suspended i der i' xtend their ha e-w t.

heads 8 and Mq on the ends of drum;shaft I provide means for exerting pull on ropes for miscellaneous purposes, 7 The. entire plant including the drag line excavator is 'mounted on a plat:- form or: floor I55provided rwith skids I56 (or wheels or rollersl as a bodily movable unit sup p t n th t ..the::ta i e sot at it can be moved bodily acrossthe surface thereof,

Force 'for moving is applied by ordinary lifting jacks I51 braced against-posts or deadmen I58.

It is. readily seen that the tai i s dischargedfrom the plant ontothe side slope or fiank of the tailing.- pile' buildup or extend the pile. about as fast as'mining proceeds lwhenever the dischargeI r m c ute r co v yo ds e q e. th

desiredlevelgof the tailing pile a. few strokes oi ahand shovel or small drag scraper pulled by mast but exceptin 5 roperf'rom the cat head serve to level the top of discharge onto the flank of the pile, r v F ure i hows1as m e ap ra s or applying .applicants method to' ore of a different type ii -which thevaluesare-chunksjor pieces which.

can. be separated by hand and visual observation atable 888 Anpperator-BQS by means oi -a hoe '8 I0 or other tooldrags the valuable pieces ofi the 'platformonto pile 8 II fir other convenient place and pushes the 1 valueless I tailing material oh the end of the platform to drop on the flank of;

tailing pilel8 l2'r,Platform 8.01 ispushed orpulled the pile. The entire plant is advanced bodily, either continuously. or. at intervals by:pulling w th a cable or by pushing with jacks .I5'I. so I that. as fastas the tailing pile is ex-l tended the discharge is 'kept close-enough; 'to the edgeof E the tailing :pile for tailings to 'it is supportedsoas to follow thepxtension' of the growing pile and discharge tailings onto the flank of the pile. The method of extracting the; valuable portion of ore inthis case ishandsort;

ing andithesepaliator is a platform and hoe.

ype h c ithe a s are ov rsi e a erial, suchas phosphate nodules orgcon'cretions of valuable Ina'Ite Tia -ina loose matrix. 'Itcon'si'stsof against a bank of placer ore to loadsaid recep-.

a drag line excavator 9M operated by cables 902 and 993 from: inastBMI: cables 'a'r'e op'erated by 'drum's r9595 driven by motor SGGI- MaSt i904 iscarrieddn a platform-crisper 901:. Thexcavator dumps its load 'on' screen or grizaly 9fl8; Fines drop through thebhute BBQ-which in turn discharges them as" tail-lugs to tailing pile; 9 l0. Oversize material rolls dovm'the screer'fto"chute 9.1! from which it is taken'b'y hand ordiv'er'ted to sacks as at EH2. Chute-909and scrcn-908 are supported on cross "pieces-.9 Iii-{and 9 l 4 onfthelegs of mast 9M and on-{support1$l5.= The entire fioortfi'i, with screer'i, mast and 'clrurns, ispu'shed or pulled bodilyas a. unit'across thetop offtailing pile fild upon which itis supported so as'to follow the, extension ofthe growing tailing-"pile and discharge t'ailings onto the fia'iikiof the' 'pile. In this case the separatoI is a simple-screenand Numerous other modifications;accessories and details of construction an'd'o a'erations'can bedescribed but will be omitted because'it isbelieved that sufiicint, description has" already been given to teach applicants invention to others.

In resume of the foregoing pages it is seen that an'imp'ortant advance has been made in the art of placer mining by applicants noveland. economical method and apparatus fordisposal and use of tailings, briefly described as follows and in the appended claims. 7 V

Ore is dug from open cuts by a drag line excavator, transported directly tothe top of a mast, and delivered to a separator (such assluices or screens) at the foot of the mast wherein valuable portions are extracted from the ore and tailings discharged directly onto the flank of a tailing pile. The mast and separator are carried on a platform or floor as a bodily movable unit or treatment plant. The plant is supported on the top of the tailing pile near the edge so that tailings discharge direct from the plant onto the flank of the pile extending the pile; As fast as the detailmay be made without departing from the spirit or scope of the invention as defined'in the appended claims.

I claim as my invention: 1. A method of mining. and treating placer ore which consists of dragging'a digging receptacle tacle with ore, transporting said receptacle with its load bodily to a mast carried bya treatment plant supported on the top of a pile of tailings from previously treated ore, dumping said load from. an elevation near the top of said mast into said plant, returning said receptacle to the bank repeatedly for additional loads of ore; extracting valuable portionsfrom said ore in said plant, discharging the rejected tailings over the side of said plant onto the flank of said tailing pile to extend said pile, and moving said plant bodily as a single unit across the top surface of said tailing pile to follow the extension of said pile closely enough for all tailings to discharge onto the flank of said pile.

2. An apparatus for placer mining consisting the, side ao f-rsaid platform; l

including'i a :iplatfor'm' 'gcarrying" thereongla i'mast fromwhich said excavato'risioperatediand 'aiiseparator'adapted :to extract values: from ore deliv-; ere'dby isaid excavator and rejecttailing's over 1;;

3. An apparatus for min ing and treating placer ore consisting of a dragline excavatorpperated by cables and a bodily movable foundation iioor supporting thereon a mast 5 from which said ex- 'cavator is. operated to" dig ore from a placer de-.-f

posit and deliver 'said'ore to a separatorsupported on said floor adjacent said mast, and a separator, adapted to extract the valuable-portions from'said ore and discharge theitailings rejected over the.

V 4; An apparatus "for mining and treating placer oreconsistinglof adrag line excavator operated cavator'is operated to digore fromaplace deposit and discharge tailing's rejected over thesideof by cables and a bodilymovable foundation floor supporting the'r'e'on a mast frorniwhich said ex'-,

and deliver 'said ore' to a screen" adjacent said. mast; a'fscreefi adjacent 'said-imast adaptedkto 1 separate and'f' 'discharge oversize materialjgffrdm said ore' overthef side-of said 11001, a separator. adapted to receivenndersizefinaterial from said screen,' extract the valuableportions therefrom said floor-adjacent the discharged oversize,; and

motive power for operating said separator.

5. An apparatus for mining and treating placer ore consisting of a drag line excavator operated i by cables and a bodily movable foundation floor supporting thereon a mast from which said excavator is operated todig ore from a placer deposit i and deliver said ore to a screen adjacent said mast, a screen adjacent said mast adapted .to separate and discharge oversize material from said ore over the side' of said .floor, a separator adapted to receive undersize material from said screen and extract valuable portions therefrom,

a'pump connected to supply water to wash material through said separator, dewatering means adapted to salvage water discharged from said separator and discharge solids separated therefrom over the side of said floor adjacent the discharged oversize, and motive power for operating said pump, separator and dewatering means. 6. An apparatus for mining and treating placer V ore consisting of a drag line excavator operated by cables and a bodily movable foundation floor supporting thereon a mast from which said exca- 7 vator isop'erated to dig ore from a placer deposit and deliver said ore to a screen adjacent said mast, a screen adjacentsaid mast adapted to separate anddischarge oversize'material from said oreover the side of said floor, a separator adapted to receive undersize material from-said screen and extract valuable portions therefrom, 1

dewatering means adapted to salvage'water discharged from said separator and discharge solidsseparated therefrom over the side of said floor adjacent the discharged oversize, vats receiving said salvaged water provided with outlets for discharging mud settlings from the water, a pump connected to pump water from said vat to said separator, and motive power for operating said pump-separator and dewatering means.

7. A method of mining andtreating placer ore which consists of digging and transporting ore froma placer deposit to a treatment/plant supported on top of a pile of tailings from previously treated ore, extracting the valuable portions from said ore, discharging the tailings rejected by said "the flank of said pile V w 8. .A method of'mining and a l i which; consists of dragging a--digging receptacle against abankof placer ore to load'said recepgtacle with oreptransporting said receptacle with its load bodilyto a mast carried by a treatment plant directly onto the flanks of said a ing we; the iar'ge pieces being depositedznear the bottom of; the; pile andthe small pieces :near othe top of v -which consists of dragging a digging receptacle 7 against a depositof placerore toloadsaid receptaclewith ore, raising said r'eceptacle clear of the ground surface, transportingsaid receptacle with thegpile, and moving said plantbodily across. the

.top of said pile to follow the extension of'said J pile'clos'ely enough'for tailings to discharge onto treating. placerore plant supported one pile oftailings from previously treated ore, dumping said load from an gelev ation adjacent the top of said mast into said plant, returning said receptacle to the bank repeatedly for additional loads 7 of. are, screening the ore in said plant, discharging theioversize over the edge of said plant fonto the-flankcf said tailing pile; treatingthe ,undersize in, said plant tov extract valuable products therefrom, discharg-' ring the tailings ircm the treated undersize over theedge of saidplant adjacent theL-oyersize discharge directly onto the flank 0f Saidtailing pile, and inojving said treatz nent plant; bodily as .a singlevunit across, the top suriace'of said'tailing pile to follow the extension of 'said pile closely 19953711 r V a "enough for all-tailings todischa-rge directly from "the treatment plant onto the flankof said pile.

g 9.1. A method of mining and treating placer ore itsload bodily and above the ground surface directly from saiddeposit to a. mast carried'by a treatment plant supported on a'pile' of tailings ifrom'previously treated ore, dumping said load into said plant from an elevation adjacent the top of said mast whilefsupporting weight of said receptacle by said mast, returning said receptacle to said deposit repeatedly for additional loads of ore, sizing the delivered'ore into portions in said plant fextracting valuable products-in said plant from one ofthesized portions, discharging anings'of spent ore over the side of said plant directly onto the flank of the tailing pile, and moving saidtreatmentplant bodily as a single unit across-the uppersurface of said tailing pile to follow the extension of said pile closely enough for all tailings to discharge directly from said plant onto the'flank of said pile.

" GEORGE A. MACREADY.

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