CA1069042A - Subterranean drilling and slurry mining - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Subterranean slurry mining with one or more mining nozzles which, during mining, directs a high pres-sure jet of liquid into a granular ore matrix to reduce the ore to a slurry which is thereafter pumped to the surface by an eductor pump including a high pressure eductor nozzle. The drilling and mining apparatus includes several different types of hydraulic control systems which operates at or below system pressure and allows the ap-paratus to be changed between the mining and a drilling mode. During drilling, the liquid is directed through an open foot valve and drill bit into the well cavity being drilled to wash the cuttings to the surface at which time the mining and eductor nozzles are closed. During mining the control systems close the foot valve and control the opening of the mining nozzle (or nozzles) and eductor nozzle.
When the control system includes one or more control conduits that extend to the surface, the system may be used to modulate the eductor nozzle, and depending upon the control system being used to selectively open or close the mining nozzle, thereby controlling the pressure or draw-down in the cavity. Self-activating control systems are disclosed and are responsive to differences be-tween system pressure and cavity pressure when the foot valve is closed to modulate the eductor nozzle. Other self-acti-vating control systems may be used to selectively open and close a pair of mining nozzles without modulating the eductor nozzle, or with provision for modulating the eductor nozzle.

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Description

sa4z CROSS REFERENCE TO REL.ATED APPLICATIONS
My copending United States Patent Application Serial No. 784,277 filed on even date herewith and assigned to the assignee of the present invention discloses in 5 detail certain components aE the present drilling and mi~ing apparatus not described in detail herein. This United States application issued as United States Patent ~o. 4,077,481.
BACKGROUND OF I~E INVENTIO~
Field of the Invent ion This invention pertains to improvements in sub~
terranean slurry mining and more particularly relates to an apparatus for drilling and mining one or more layers o~ granular ore, such as phosphate ore, without 15 withdrawing the apparatus from the well cavity between the drilling and mining phases.
Description of the Prior Art Subterranean slurry mining o~ phosphates or the like is broadly known in the art as evidenced by United States Wenneborg et al Patents 3,730,592 and 3,747,69G which issued on May 1, 1973 and July 24, 1973, respectively, and are assigned to the assignee of the present invention.
The modified embodiment of the apparatus dis-closed in Wenneborg et al 3,747,696 is pertinent and 25 comprises a corr~bination slurry drilling and mining apparatus which may be changed between its drilling mode of operation and its mining mode of operation to mine several layers of , :- . ., ' ~ ' ~ ' 1~69~
ore withouk requiring that the appara~us b~ pulle~ out o:~
~he hol~: or well cavit~ However, the h~draulic con~ro~
system :Evr changing the several valves from the drilling moae ~o the mining mo~le re~uires a posi~ive pressure o~
abc: ut 2000 psig ~ in the prior art device which is much gr~at~r than the approxima-~el~ 1000 p5ig mining pressure.
The prior ar~ h~rdraulic sy~tem ~:hus ~equire~ additional high pressure pumping equipment, and is also su~ o ~Iam~ge due to the very higk con~rol pre~sures a~ er ha~mner ty~?~ ;Eor~es which ma~ be ap3plie~ to the system~
Wenne~org et al 3,730,592 discloses a method whch contempla~es the use of~ surface controlled pre~s~re~
et~ual ~c~ or in excess o:E the drilli~g pressu~e :f~r shifting the ~nin~ no~zle, the eductor nozzie, ~nd the ~xlll bi~
. . .
:Eoot valve be~ween the driILing moae and the minirlg IT~de In adaition, the pa~entee discloses ~he u5e o;~ con~rol pres~
sures which lie in a x.ange ~etween the arillin~ pressure an~ a mining pressur~ for :modula~i~g the mining nozzle.
- Modulation o~ the mi~ing nozzle is effec~i~e to-control the

2~ cavity pxessure, and also the li~uid level in the mined cavi~y to v~ry ~he mining condi~ions for the particular s~ra~a ~ing mined~ : :
Unite~ States parent and divisional pat~n~
numbe.rs 3~1SS,177 a~d 3,31~!985 which ~ssued to ~.B~ Fly on Novel~er 3~ 1964 and Ma~ 2, 1967~ respectivel~, dis-cl~se a ma~od and ap~ara~us ~or under-reaming or slurry mining a well, and can also be controlle~ to alternately bore deeper and mine other strata in the well af~er the first boring an~ mining operation ha~e heen complete Val~res operated by electric motors located within ~he too ~L~69~4;~

string convert the apparatus from a drilling operation to a mining operation. The amount of force that can be applied to convert the apparatus from the drilling operation to the mining operation is, accordingly, limited by the size of the electric motors that can fit within the tool string.
In acco~dance with the present invention a foot valve positioned betwe~n a first pressure zone subjected to variable system pressure and flow rates and a second pressure zone which pressure varies from slightly less than system pressure to ~avity pressure, depending upon the flow rate and position of the foot valve cavity pressures therein is provided and includes the combination of an apertured valve seat for establishing fluid communication between said zones, a valve plug movable between an open position permitting flow of liquid through said valve seat and a closed position at least substantially terminating flow through said valve seat, a dash pot disposed in the first zone and associated with said plug to reduce the rate of closure of sa}d plug; said dash pot including a housing communicating with said first pressure zone through bleed passage defining means for allowing liquid to enter said housing, a piston rod slidahly received in said housing, a piston connected to said piston rod and dis-posed within said housing, resilient means disposed be-tween a portion of said housing and said piston for urging said foot valve plug toward its open positbn, and means defining a bleed passage extending from one side of said piston to the other.

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' BRIEF DESCRIPTIO~ OF T~ DRA~INGS
Figure 1 is a diagrammatic elevation o~ the drilling and mining apparatus of the present invention shown in its mining mode of operation, certain parts being cut away.
Figure 2 is a diagrammatic central vertical section taken at a larger scale and illustrating the operative components of the drilling and mining apparatus.
Figure 3 is an enlarged central section taken along lines 3-3 of Figure 4 illustrating a first embodi-ment of the eductor pump section.
Figure 4 is a horizontal section t~ken along lines 4-4 of Figure 3 at a reduced seale.
Figure 5 is a sehematie diagram of a first hydraulie eontrol system having con~5rol lines to the sur-face and being effective to modulate the eductor nozzle and also control the opening and closing of the mining ~, ` ~L06904~2 i~cludes two mining nozzles. Thi9 control system is activated by variations in the system pressure to modulate the eductor nozzle and senses momentary variations of greater pressure changes to alternately open and close the two mining nozzles. If desired, this sixth control system may be separated into two separate componen-ts with one component operating onl~ the mining nozzles and/or the other component operating the eductor nozzle.
A fourth embodiment of the eductor nozzle is quite similar to the third emhodiment except that the nozzle is adapted to be modulated under the control of j either systems having control lines to the surface or self-activating control systems.
In accordance with the present invention a foot valve positioned between a first pressure æone subjected to variable system pressure and ~low rates and a second pressure zone which pressure varies from slightly less than system pressure to cavity pressure, depending ~pon the flow ! , rate and position of the foot valve cavity pressures therein is provided and includes the combination of an apertured valve seat for establishing fluid communication between said zones, a valve plug movable between an open position penmitting flow of liquid through said valve seat and a closed position at least substantially terminating flow through said valve seat, a dash pot aisposed in the first zone and associated with said plug to reduce the rate of closure of said plug; said dash pot including a housing communicating with said first pressure zone through bleed passage defining means for allowing liquid to enter said housing, a piston rod slidably received in said $~ -5~ - ' :

~L~690~2 housing, a piston connected to said piston rod and dis-posed within said housing, resilient means disposed be-tween a portion of said housing and said piston ~or urging said foot valve plug toward its open position, and means defining a bleed passage extending from one side : of said piston to the~other.
:~ BRIEF DESCRIPTIO~ OF TE~ DRA~I~GS
Figure 1 is a diagrammatic elevation of the drilling and mining apparatus of the present invention shown in its mining mode of aperation, certain parts being cut away.
Figure 2 is a diagrammatic central vertical section taken at a larger scale and illustrating the .~ .
operative components of the drilling and mining apparatus.
Figure 3 is an enlarged central section taken along lines 3~3 of Figure 4 illustrating a first e~bodi-ment of the eductor pump section.
Figure 4 is a horizontal section taken along lines 4-4 of Figure 3 at a xeduced scale.
Figure 5 is a schematic diagram of a first hydraulic control system having control lines.to the sur-face and being effective to modulate the eductor nozzle and also control the opening and closing of the mining .

-5a-: ~0~69~42 nozzle, one o~ said lines communicating with ca~it~ b-low the :~oo~ valve to perrni-~ SenSiIlg cavity pressure_ , ~igure 6 is a sche~atic diagram illus~ra~ing a secon~ hyaraulic con~rol system ~hat ineludes con~xo~
lines to the surface which is effective to modula~e ~e eductor nozzle and aiso selec~ively opens ana closes each mini~g nozzle.
- ~igure 7 is a central verti.cal sec~io~ illus~
tratin~ a ge~ond embodi~en~ o~ a portion o~ an eductor n~zzle which ma~ be subs~ituted in ~he appara~us for the e~uI~alant p~rtion-~ of the eauc~or nozzle o ~he ~irst e~bodiment o~ the i~en~ion.
Figure 8 is a schematic diagram illus~rati~g . thira hyaraulic control system which is sel~-ac~iva~ins 1~ ana non~moaulatin~ for use with the ~uc~or nozzle o~
Figure 7 ~ igure 9 is a vertica~ section oL a thi~
embodimen~ of an eductor nozzle associated wi~h an in~erte~
self-cleaning dash po~ ~hat aiso ~orms a portio~ o~ the foot va~ve.
Figure 10 is a schematic dia~ram i]lustrating a ~ouxth hyarauiic control s~stem tha~ .~s sel.f.-ac~iva~ing .
ana non-mo~ul~ting for use with the eductor hoZzle o~ --. Figure 9~ . ~
Figuxe 11 is a vertical section o~ ~ Pra~men~ ~f a ourth emboaiment of the eductor ~zzle associa~ed wi~h an invertea sel~-cleaning dash pot and ~oot valve tha~ is quite similar to Figure 9 except that i~ is modified to be connectea to an eductor nozzle modulatiny co~trol system Figure 12 is a schematic diagram illust~atiny a 69~Z
~i~th hydraulic control system that is sel~-activa~i~g and modulating ~or use with the eductor nozzles o~ ~igur~ 3 and 7 when associa~ed with a single mining nozzle:
Figure 13 is a schema~ic diagram illus~ra~ing a six~h hydraulic control sys~em that is sel~-ac~ivaiing and modulating ~or use ~Jith the eductor nozzles o~ ~igur~s : 3 and 7 when associa~ed with two mining nozzles.
DESCRIPTIO~ OP TEE P~X~ERRED ~MBO~D~E~T
. . - - The subterranean drilling a~d slurry mining ap-` 10 paratus 30 ~Fig~. 1 and 2) of ~he present in~entio~ is supp~r~ed on a mobile ~ehicle such as a barg~ 32 ~loatins i~ a pond 34 over the mining site, Conven~lonal component~
; o~ a well drill;ng rig 35 on the barge are employed during the drilling mode o~ operation to a~semble the min~ng and ~5 drillin~ appara~us 30 section ~ section, Prior to drill-ing, ~h~ ~ig 3~ is used to drive a lar~e diameter con .
ductor pipe 37 into the ~loor o~ ~he pond 34 ~o prevent the wa~er in the pond ~rom flowing in-to the well cavi~yD
The appara~us i~ then operaked in its mining mode to LemOVe 2~ and collect a slurxy o li~uid and ore from the matr~x being mined. After thP reclaimable gxanular ore has bePn minea from one or more ore matrixeS at ~he mining site~ t~e apparatus is pulled ~rom the well and is disassembled ~ ena~ling ~he barge to be moved to another si~e~
Al~hough the apparatus 30 is primarily ~ntended ~or use in mining phosphates from o~e or more ore strata at rdepth& between about 200 ana 300 ~eet below ~he surface, it ~11 be understood that the apparatus may ~e used at . other depths; or for mining other types o~ ore including non-metallic materials. It ~Jill be understood that the term 9~2 "oxe" as used her~3in includes gravel, rocks, or any other solid that the apparatus is capable o:E slurry pumping to the surface. It will also ~e unders~ood th~: the apparatus is capa~le o:E ha~dling ore as large as four inches in 5 diameter although'~e normal consistency of ~he phosphate ore is som2what like sand.
:i:n general, the dri1ling an~ mi.~ing appa~us 30, - . . whe~ ~ully assembled in its mining moae,include~ a tool string 3~ tha~ e~ten~s down~ardl~ ~hrough the conauc~or pipe 37 and has a con~entional rotaxy bit assembly 3~ at i~5 l~wer ena- It will be understood that the bi~ 38 includes-~owe~ cut-~ers 40 and 5i~ cut~ or underream~rs 42 that co~pera~e ~a boxe a hole or well cavi~y tha~ is somewhat larger in diameker ~han the ~oo} ~ri~g. The bi~
i~clude~ a tubular water pa5sage 41 having orifices 41' ~t i~ lower ~nd which restxicts the flow therethrough . an~ aids the drilling operation by ~ixecting jets o~ water into the hole be;n~ drilledr The side cutters 42 are plvotea inwardl~ when the tool is being ~ulled to ~he sur-fac~ a~ter the ~re has been aepleted from ~he mining site~ -A~ ed~lctor pump section 44 is connected to ~he upper end . .
of the drill ~it 38 an~ a mining noz~le section 45,-which ~ .
includes a mining nozzle ~6, is connected to the upper ena .
o~.the eductor section 4~.. A plurality of dual string pipe 2S sections 48 (Fig. 1~ are connected toge~her and ~o the mining nozzle section 45 and extend upwar~ly ~o ~he su~ace, Each pipe section 48 includes an inner s~ring conduit sectlon 50 ~Fig. 2) defining a tubular slurry passage, an ou~er strillg conduit section 52 which with the inner section 50 defines an outer annular water passage, a con~rol line 54 ` ~
~ 06~0~2 (Figs~ ~ and 5) and a avity pr~ssure sensing co~trol line ~6 which with the i~luid system pressure between ~he conduits 50,52 de~ine a hydraulic control system 57 (Fig. 5~ The upper enc~ o the uppermost pipe sec~ion ~8 is connec-.ed ~o 5 a swivel ioint 58 ~Fig. ~) that forms a portion of a mining .
head 60~ The mining head 60 includes a ~hreade~ tool sup-; , port coupling 62 that receives and is su~por~ed~y a - threade~ s~ivel sub~as~em~ly or dr~lling h~ad 64 The drilling head 64 is supportea by a h~aulic- .
all~ driv~n power swi~el 66 (Fi~ o~ the we~l riy 35~
~h~ power swivel 66 is ~uided for vertical m~vement alons . . the ~rame 68 o~ a mast 70 and is xaised ana low~red ~y a - power ~ri~en lOn ton cable ~oist 72. The ~ower sw~vel 66 a~a the hoist 72 ar~ use~ to suppo ~ ~he tool str~ng 36 during ~hs mining mode of operation and also for xaising ~r lowering) khe tool s~ring a l~mited am~unt while mining~
i~ desired, in or~er to chan~e the vertical loca~ion o~ a jet o~ water being disc~axged ~rom the ninin.g nozzle for more e~fe~i~ely breaking up th~ granular ore matrLx bein~
mined~
The drilling head 64 an~ p~wer swivel 66 are also used as a unit to s~rew each section o~ ~he tool s~rin~ 36 toge~ther ana to direct wa~er downwar~l~ thxuug~ the ou~er ~nduit 5~ ana ~hrou~h the drill bi~ during the ~rilling . 25 mode~ Similarly~ the drilling head and pow~r swivel unit : is used to unscrew the pipe sec~ions of the ~ool s~ring 36 ~rom each o~er when ~he appara~us is being pulled *rom the well cavity. ~uxing the arilling and pulling opera~ions a well known well loading unit 74, torque wrench 76, and ~ool slip 78 cooperate with the powe~swi~el 66 in a ~.anner .

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well knownin the art to perform the drilling and pulling ~unct.ions It will also be noted that the mast 70 is .. . . .
pi~otally connected to the barge 32 and may be pivoted away ~rom the well as indicated in dotted lines to permit other s~andard well drilling operations to be performed when drilling the well cavity. Drilling and mining li~uid, hereina~ter referred to as water, is directea In~o ~e outer conduit 52 at ~ariable pressures an~ capacities by a pump Po c~ntrol valve 82 and condui~ 84_ ; ~11 components o~ the drilling and mi~iRg ap~
paratus 30 o~ the p~esen~ invention; except for the severa~
e~bodim~t~ o~ ~he eaucto~ pump sections ~4, an~ ~he contr~l S~S~em~ 57 ~or ac~uating the edu~r pump sectio~s and the mining noz21es 46, arë substantiall~ the same as the ~omponents descri~ed in m~ above identi~.ied cope~ding ~pplication. Accordingly, onl~ the new comp~nen.s o~ the eductor pu~ sections and the control systems ~here~or wil~
~e descri~d i~ detail~ Reference may be had ~o my co-pe~ding applica~ion *ox details of ~he appara~us 30 ~ot speci~icall~ ~escribe~ herein~

MOD~IATING ED~CTOR NOZ~LE . ~ :
. WIT~ SURF~CE CONTRO~
~ lle ~irst embodiments o~ the edu~or pwmp sectio~
4~ ~Figs. 3-5~ is provided with a modulating eductor nozzle.
10~ that operakes independentiy *rom a sel~-actua~ing ~oo~
~alve 102.
The eductor pump section 4~ includes an i~ner string conduit section 104 ~ig~ ~) of ~he inner str}ng 50~
and an ou~er s~ring conduit section 106 of the outer string 52V which ou~er section is provide~ with diame~ricall~

~ .
, .

:~69a~4Z
opposed slurr~y inlet openings 108 (Fîgs. 3 and ~ of a ~lurry inlet section 110 imrnedia~el~ adja~en~ the eductor nozzle 100.
:, .. .
The lower portion o~ the ou-~er conduit sec~ion 106 includes a centxall~r apertured lo.s~er flange 112, an intermeaia~e ~lange 114, a nozzle seat :Elange 116 an~l a ~en~uri tlibe flange 118~ The :Elange 11~ supports th~ lower - en~ of a ~entu~ri tr~be 120 ~igs. 2 and 3) which fo~;~s the ~ lower por~:ion of the inner coriauit 50. However, mining liqui~ (herai~a:i~t~r re:~erred ~o as water) must :Elow :Erom above the upper 1ange 118 to a posi~ion ~elow the ~la~ges - ~ ~14 and 116 w~thout en~ering the slurr~ inLe~ sec~ion lli:~
exc~p~ throug~ the eductor nozzle 100 as will }:~e describea ~elo~
Accordingl~r, a pair o~E closed ~enerally arcua~e condt~it ~;ections. 122 ~Fig. 4) are ri~ridl~ securea be~ween the slur~ c~penings 108 to assure that all drilling and mIning wat~r ~lows down~araly below the flan~es 114 and 116 f~or :Eurth~er distrihu~ n . E:ac~h arcuate condui t sec~- on 122 i~ de~ a pQrtion o~ the outer conduit 106, an arcua~e - lnner conduit por~ion 124 9 and edge portio~s 12~ that defi~e opposite sldes o~ the s lurry inlet openirlgs 108 .. Grilles - 128 are ~olted to the edge portions 1~6 of~ adjace~l: arcua~e sections and include spaced horizoIltal pla~:es 130 an~
25 ~ertica7 roas 132 spaced about two inches apar~ to li~it ~he size of the articles which may be drawn i~to t~e slurry openings 108. ~ plurality o~ holes 134 (only one being sho~n in Figure 3) are provided in the intermediate ~7ange 11~ there~y allowing the water to flow the~epast and .hrough 30 the foot val~e 102 when the foot ~alve is open.

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ii9C~42 A parabolic nozzle seat 136 having a port 137 therein is rigial~ connected and 5ealed to the apertured :~lange 116 b~ capscrews ex~ending ~hrough an annular ring 138~ an 0-ring 140 and cooperating snap ~ing 1 2.
An educ-~or va~e plug 144 is movable between ~he illus-trated closed position and a position which opens .ne pt)rt 137 varying amo~m~s }:~ a piston 146~ The pisto~
146 is recei~ed in a cyli~der 148 that is xigidly secured to a base lS0, which base is secured ~o the f~la~ga 114 b3~r a plurali ty o:f spacers 152 . T~e educt:or n~zzle plus 144 ~; . is bcll~ed to a swi~7el plate 154 ~hat is con~cte~ to the upper end o a piston rod 156 o:~ the pisto~ ~y a snap rin~
157 and a fnxs~o~co~ica~ ollar 160 that is rece.ived ~ a ... . . . .
rusto-conical bore in the swivel plate. The e~luc:tor nozzle plug 144 and piston 146 def~ines a ~?:Lug-pis~on un~t,.
Thus, ~he upper ena o:E the nozzle plug 144 may pivo~
s~ightl~ relative to the axis o:f~ t~Le pis~on ~o assur~3 proper seating o~ he plug 144 in the port 137 when ~he educ~or nozzle is closed~, ~ 20 The piston 146 includes ~he pis~on.rod 156.whic~
has a lower aamping portion 158 exten~irg through an aperture in an inte~meaiate wall 160 in the cyli~er, The lower damping portion 158 o~ ~he piston r~ 6 aIso ......... .... ....... . ~nters an oversize bbre 162 in ~he base~ The bore 162 forms part o~ a co~trol conduit 164 that is conne~ted ~.o control line 54. Holes 166 are ~ormea in the wall 1~0 to permit passage of liquid past ~he wall 160. Entry o~ the damping portion 158 o~ the piston ro~ 156 intn the over-size bore 162 ~urther limits the rate o~ opening o~ the eductor no~zle lOOo ~ -12 ~t;9 ata~z A rela~ively weak, small diameter compression spring 167 maintains the eductor nozzle 100 closed when no li~uid pressure i~ being applied to the eductor sect~.on~
The spring :L67 is disposed betwe~n the swivel plate 154 and a spacer 16~ supportea b~ the base 150. A heavier spring 170 is supported by a shim ox spacer ring 172 on the base and is space~ from the swi~el plate 154 whe~ t~e eauc~or no~zle 100 is closed. A~er the nozzle is partiall~
~pened~ th heavier sp~ing 170 ~on~ac~s the plate 154 to coopera~e wl~h control liquid entering the con~ro~ end o~
the cylinder rom contrcl line 54 ~o modula~e ~he noæzle - p~ug 1~4 thereby regulating the deg.ree o~ ope~in~ of ~he eductor n~zzle 100.
As indioatea in ~igures 3 and SJ the con~rol 15 candui-~ or line 54 extends to the sur~ae and is co~ecte~
to the ~n~rol end o~ the cylinaer 148 ~h.rou5h the conduit 164. A ~alve 174 on the upper en~ o~ the control line 54 ~a~ ~e actuated between positions ven,ing -~he ~o~trol line 54 to thP atmosphere and directin~ control pressur~ i~t~
- ~0 the ~o~rol line 54 and c~linder 148~ The cavi~y pressuxe -~ontrol line 56 includes a valve 175 (Fig~ 5~ a~ i~s upper end and is con~ctea b~ tubing 176 (Fig~ 3~ a pipe tee 178, and a short conduit 180 to a passage 182 which e:on~nunica~e~ with ~he well cavity th.rough ~he tu~ular ~5 ~as~age 41 in the drill bit 38 (Fig~ 2) i~ an environmen~
of clean ~lowiny water~ The drill bit is scre~ed into a flange 184 (~ig~ 3j bol-ted to the previous~y mentioned ~lange ~ As indicated in Figure 30 the lower ends o~
the ~ertical portions of the control lines 54 and 56 are supported by ~racke~s 186 and 188 that are rigidly secured to the base 150. 0-ring seals are pro~idea to isola~e the liquid in the control lines 54 and 56 from the surrounding dxilling and mining liquid. I~ desired, flow resis~ing . means 189 (Fig.. 5) ma~ be inserte~ in conduit 176 to provide 5 sufficien~ resistance in the conduit 56 to allow hia~ pres-sure water entering the conault ~o at~a}n subst~ntially mining system pressure thereb~ closing the mininy nozæle 4 - T~e foo~ valve 1~2 (Fig~ 3~ is selr~ac~iva~;.ng and is not directl~ connectea to ~he eauc~o~ n~zzle plug 144 as was the case in my a~ove men~ioned copending ~ppli : ca~ion, bùt opera~es indepenaently o~ the educ~or nozzle 144, ~h~ ~oo~ valve 102 comprises a flanged valve sea~
200 which is pres~ ted ;nto the ~lange 184. A ~oot v~lve ~a~h po~ 203 includes a aampin~ cyli.nder 204 which is ~olte~ ~o a cylinder support base 206 that is xigidly secured to a ring 202 that is b~lted to ~he ~lange 184 an~
has a plurality o~ large flow passages 208 the~ein, The cylinder ~upport 206 includes an upstanding sha~ gu~de 210 which is apertured to receive an in~e~media~e aiamete~
por~ion o~ a shouldered sha~t 212 to which a foo~ valve plug 214 is secured. The ~oot valve plug 214 includes spaced yui~e var~es.216 that are slida~1~ received in a p~r~
i~ the vaive seat ~00 and which permit liquid ~o ~low into 2~ the well c~ y when in the open posi~n illu trate~ in Figure 3, The ~oot valve plug 214 also includes a small diameter passa~e 217 which permits a 5mall amoun~ of water to enter the tube 41 in the drill bit assembly 3~ during ~inin~ when the Foot valve is closed~
A damper piston 218 is ~lt~d to the upper en~

369~
of a shouldered sha~t 212 and has its outer peripheral sur~ace dispDsed within and slightly spaced from a cylindrl-cal bore 220 ~ormed in a cap 222 that is bolted ~o the u~per ena of the damping c~linder 204, when the foo~ ~alve is open as illustrated. The upper portion o~ the cylin~er 204 is provided with a frusto-conical ~ore 224 whic~
communica~es wi~h the ~ore 220 ana a sm~ller diame~er bore 2Z6 wi~hi~ which the damping piston is se~ed in fluia tigh~ engag~m~nt w~n the ~oot`val~e 102 is closed. Small : aiametar bleed hole~ 228 and 230 are ~ormea i~ ~h~ cap 22~ and d2mper pis~on 218, respectively, ~or permi~ng .liqui~ to sle~wly flow therethrough when tb.e ~oot ~a~e 102 is being o~P~e~.or ~losedO A spring 232 ~isposea hetw~en ~; the piskon ~18 and ~he cylinder su,~port 206 holds the ~oot 15 ~ralve open during drilling- and whe~ little or no dif~eren tial pr ssu~e is applied across the ~oot valve as occurs ~luring ~h~ drilling mode.
. ~'he modulating control system 57 ~or the dri? ling an~ mining apparatus 30 is provided with a sinsle mining ~0 n~zzle 4~ is illustratea in Figu~e 5, ana will be de-scr~bed in conjunction with the operatio~ o~ ~h~ apparatus 30~ ::n the disc~ussic)~ to :~ollow, .it will be un~lerstood ~ ~hat the term "s~stem pressure" re~ers to~e water pressure in the outer ~nnulax conduit 52 (Fiys~ 2 and 3~ which 2~ system pressure is about 300 psig auring dri3ing and is aDout 700 ~o 1000 psig du.ring mining The s~st~ pr2ssure is taken at the surface and accordingly does not include the pressure heaa due to the heigh-t o~ water above the eauctor no~zle section 75. It will be understo~d that ~he pressure in the drill bit water passage 41 is at substantially syste~

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690g~ -; pressure when ~he ~oo~ valve 102 is open bu~ is a~ cavity pressure w~en the foot valve is closed.
Duxing drllling, water is directed into ~he outer conduit 52 at about 140n gallons per minu~e and 2~ 2 sy~m pressure . at ~ about 300 ps-g. A~ this time~ .he upper ends of the con~rol condui.s 54 and 56 (Fig. 5) are als~
open ~o system pres5ure, Thus, t~e hydraulic pr~ssure act-ing on opposi~e siaes o~ the piston 14~ o~ t~e edu~tor noz21e 100 is "o~Prbalanced" upwardl~ since t~e pis~on area~
subjected to upward and ~own~ard s~stem pressure are egual excQpt-~or the area de~ined by ~he ~ip of ~he plug 144 which pro~ec~s through ~he nozzle port 137 an~ is su~iectea . . . to the much lo.wer ca~it~ ~ressure. This "overbalancedn.
hydraulic pressure is aided by thë sprin~ 167 ~o hold the . 15 edu~tor nozzle 100 closed~ Likewise, the cavity sensing.
co~trol l~ne 5~ dire~ts s~s~em pressure w:~thin a ~ylinder 24~ o~ the mining nozzle ~6 thus cooperating ~Ji~h a 5pring ~42 to ur~e the mining nozzle plug-piston u~it 243 ana the mi~ing nozzle 46 into closed position~ At ~his ~imer sys~em ~0 pressure ac~ing in the opposite ~irect~on on ~he ex~ernal sur~aces of the piston 243 is "overbalanced" ~y s~stem pressure wi~hin the c~linder 240 because o~ area dif- .
ferences ac-ted upon ~y h~draulic sys~e~ pressure ~s indi-cate~ above~ Cavit~ p~ssure control line 56 al50 dîrects ~ystem pressure into the condui~ 41 below the ~oo~ valve 102~
Although the flow o~ 1400 gallons pe~ m~nu~e during drillin~ through the ~oot valve 102 crea~es a pres-sure drop across the foot valve, such pressure arop i5 not enough to cause the downward force acting on he ~oot -16- .

~:969~)42 valve to overcome the ~orce of the spring 232 In the pxeferrea emboaiment o~ t~e inventionO the pressure drop acxoss the ~oot valve during drilling provides a closins ~orce of about 135 pounds, whereas a closing ror~e o' 2bou~
200 pounds would ~e re~uired to overco~e the spring preload.
Most o~ the 3~0 psig pressure used in drilling is dissipatea across the ori~ices in t~e arilling bit. The pressure below the foo~ ~al~e is nearly the same as system pressu~e~
ter the well cavi~y has been driLled to ~h~
`desired mining depth and ~he apparatus 30 has been assemble~
~ its mining mode~ the sys~em pre~sure is increased ~o ahou~ ~50 psig corresponding to a ~low rate o~ about 1700 gallons per minute. This rate o~ $1OW across the ~oo~
.
valve increases.the pressure drop abou~ 50 percen~ thu~
overcoming the resistin~ ~orc~ o~ the spring 23~ (Fi~ 3) ~ causi.ng the foot valve to commence closin~ As the ~oot v~l~ star~s closing~ ~he pressur~ drop increases with ~he opposiny spring force ini~ially increasing at abo~t the . same rate, thus minimizing t~ chances o~ the ~alve being closed due to a momentary hydraulic 5hock during ~rilling.
....... ... ...... ..Further closing of the valve great1y increases the pressure - di~feren~ial across the foo~ valve, and thus ~enas to cause the ~a~ve to rapidly close which, i~ permLtted, ~Jould xesu1t - in a severe wa~er hammer shock.
- ~5 The dash pot 203 is provide~ to reauce the closing rate of the *oot valve 102 to a maximum o~ about one-hal~
foot per second. During initial closing of the ~ot ~alve, water flows ~hrough the bleed passage 230 ~Fig. 3) in the piston 218 ana also between the outer periphery of the piston 218 and the surface of the bore 22~ to provide fairly -17- .

~069~2 rapid initial closing move~n-t. As the pis~on 21~ moves ~urkher down in~o the ~rusto-coni~al surface 2~4, the ~low o~ uid arouna the perip~ery o~ the pis~o~ graduall~
..
decreases, and such peripheral flow termina~es ~or sub-: 5 s~antially terminates) when the pi5~0n enters the smalldiameter bore 226. The closing ra~e of the pis~on 218 and ~oot valve plug 214 is main~ained substantially cons~a~t sin~e the water within the dash pot cylin~er 204 m~s~ t~e~
~low onl~ ~hrough ~he small bl~ea hol~ ~30 ~hen p~rmitt~ng . 10 f~nal cl~sing of ~he oo~ valve 102 The preesuxe below the ~oo~ val~e decreases.as the foot v~lve closes9 being subs~an~ially equal to cavity pressure when ~he va~e is ~lose~. Duxing t~is poi~t in the cycle co~r~l valv~ 175 (Fig. 5) in the caYity sensing line S~ ls closed ~oprevent.
: 15 discha~ge ~f system pressure~ When the fo~t valve is closea, the.pressure there~elow is subs~an~ially ca~ity ` pressure thus opening the min~ng nozzle 46~ ~ter the minIng.no~le is open, ~he valve 1~5 may be opened ~o a mete~ ~low o~ compressed air thus permitt.~ng cavity pres~
sure to be measured and recorded at the sux~ace~
With the mining nozzle vpen and the ~oo~ valve ~0~ cl~sed~ a high pressure jet o~ wa~r is direc~ed in~o ~he o*e s~rata at abbut 7~0-1000 psig thus reducl~g the ore to a slurry. At this time the pump ca~aci~ is abo~ .
6000 t~ 4000 gallons per minute. As ull~ discussed in my a~orementioned copending applicationO the tool s~ring 36 is rotated during mining thus enabling the je~ o~ wa~er to ~orm a large generally cylindrical cavity in the ore matrix by reducing the granular ore ~hat haa been in the cavity to a slurry o~ ore and ~7aterO
. -18-' .

~L~6~f)4 ~ n order to pump the slurry to the surface through the ~en~uri tuhe 1~0 (Fig 2) and-the i~ner pipe string 50r the eductor nozzle is partiall~ or completely opened b~ actua~ion of the control valve 174 (Fig 5) at . the surface When the val~re 174 is fully opened to receive full system pr~ssure o~0 for example, 1000 psigr the hy-draulic pressure acting on both ends o~ the eductor nozzle pisto~ 146 will be at s~s~em pressure and wQll there~ore -be hydraulicall~ over~ala~ed" to the clos~d pos~tion, ~hi~ ~orca pl~s the ~orce o the spring 167 w~lll hold the .
eductor plug 144 closed~.causing lit~le i~ ~ny slurry to be pu~pea ~o the sur~ace through t~e i~ner pipe string 50_ the valve 174 is full~ vented ~o the atmosph~rer the.
systam pr~ssure ~f 1000 psig will overcome the closing lS orce ~f springs 167 ana 170 thus full~ opening ~he eductor nozzle 100 ~her~by directing slurry a~ its maxLmum rate I to the sur~ace through the inner pipe s~ring 50 for colle~ion~
I* it is desired to con~rol or vary.ca~i~y pres~
Z0 sure, or ~o produce draw down o~ the li~uid level below the mining noz~le, the ~ontrol va~ 174 (whi~h may be au~oma~
tical~y.con~xolled~ may ~e adjusted ~o modulate the eductor nozzle plug 14~ ~hereby con~rolling ~he rate ~ which the slurry is pumped to the surface~
~n an apparatus 30 designed to operate with a arilling sys~em pressure o~ about 300 psig and a mininy system pressure of about lQ00 psigO the mo~ulating control pressure pre~erably lies within a modulating range of between about 150 to 500 psig. ~t is, of course, under-stood that this pressure range is given by w~y of example .. . . .

10~9(~4~
ana tha-t the pre~ure xe~uired when mining a~ substantially ; di~erent levels or with di~erent size e~uipmen~ may vary . considerably :. As mentioned previously, the rela~ivel~ weak spring 167 (Figs. 3 and 5) permits the eauctor plug to open a small amount be~ore the heavy spring 170 is eontacted by ~he swivel pla~e 154~ ~he thickn~ss.o~ the spacex ring 172 may be selecte~ as desired and such s~lec~io~ de~ermi~e~
the percentage o~ ~ull open tha~ ~he nozzl~ plug w~ll xeach prior to ~ngagin~ t~e heav~ sprin~, For example~ an ini~ial - ~o~zle ~pRi~g of 6~ percen~g which is achieved by re~ucins th~ pre~sure in the con~rol line 54 to slig~ly aboYe 50~
ps~g~ pro~iae~ a modulating range o~ 40 percen~. Thu~, by .
~arying t~e control-pressure between about.500 to 150 psig . 15 in line 54 by selec~ive ac~uation of ~he valve 174, ~he ~ ~ edu~tor nozæle openi~g is varied be~ween its ~0 percent open and ~ull open positions.

SUR~A~E CO~rROL~ED D~L ~ ING ~O~ZLE CO~TR0 S~EM WTT~ MO~ULATING E~U~0~ ~O~ZLE
- ~igure ~ illustrates an eductor nozzle moaulating contro~ sys~em 57a ~or a drilling and minin~ appara~us 30a which is substantiall~ the same as ~he ab~ve de5cribed apparatus 30 except that two minin~ .nozzle~ 46l and 6a ~re provi~ed instead o~ a single minin~ nozzle, As indi~

cate~ in greater detail in my aforemen~ioned copendin~

~pplication~ two ~r more layers of granular ore are some ~imes present in the area being mined. Thus, i~ becomes advantage~us if both la~ers can be mined wi~hout requiring that the apparatus be chan~ed ~rom its mining mode to its drilling m~de and back to its mining mode in order to m~ne . .

;9042the ~wo la~e~s of ore. This can ~e accomplished by the alternate use o~ two (or more) minng nozzles 4.6' and 46a positioned at the ~esired height to mine associated ore layers or matrixes. ~t will be unders~ooa tha~ the ore which is redu.cea to a slurry by each mining nozzle 46'~46a will ~ravitate downwardly and will be pu~ped ~o ~he surlace by the same eauctor nozzle ~OOa ~.d the components asso~
ciate~ -therewith~
- Since the apparatus 30~ and the control system 57a are 5ubs~a~iall~:~he same as tho5e previ~usl~ de~
scribed, o~ly the ~ifference~ will be described in de~ail~
Pa~s- o~ the con-~rol system 57a which are equlvalent to the co~trol system 57.~ill be assigned the same nwm~rals.
f~llowed by the letter "a". : .

. . .
: 15 As in~i~ated in Figure 6, contro:L line 54a with ~on~rol ~al.~e 174a therein is connected to~he c~linder 240' the mining no~zle 4~' and to one end of a shuttle valve 250:---having a core 25~ therein that is shifte~ b~ pres-sure ~ erences acting on its opposite endsO Simil21yO
2~ . the con~rol line 56a wi~h co~rol valve 175a therein is connected to the c~linder 240a o~ mining nozzle 46a and to the other end of the shut~le valve 250~ ~ branch conduit 254 is connected between the control conduit 54a and a . .cro~s passage 256 in-the ~al~e 250.which communicates with . .25 the cylinder 148a of the educto~ nozzle lOOa through a . . . . . . . . .
conauit 258 when ~e core 252 is shifted to ~he left as indicated in Figure 6. In order to shift ~he core 252 to the illustratea position, the control valve 175a is open to system pressure ~or example about 1000 p5ig) thus

3~ maintaining the mining nozzle 46a closea. The control ;9i[~4Z

valve 174a is completel~ vented or is partially vented to ~rovide a ~ontrol pressure that is less than system pressure thus openlny mininy nozzle 46 ' . At this tlme~ a branch conduit 260 connec~ed between the ~ontrol conduit 56a and ~he shut~le valv~ 250 is closed ~y the core 252.
With the shuttle valve 250 positioned as above described, the con~rol valve 174a may b~ ma~ually or automatically con~rollea to vary the pressure ~etween .
abotlt ~00 to 150 p5ig in control line 54a,, ~ondui~ 258, and ll:) e~uctor nozzï~ cyliIlder 1~8a, This varying co~rol pressure in the educ~or noz~le c~rlinder 148a will cause th~ educ~or le to modulate as previou~l~ descxibed Also, c~ontrol . - pres~ure wlthi~ ~he modulating range of~ 150-500 psig will .- T~O~ be sui~icient. to close the mi~ng nozzle 46' as de-15 scribed in mo~e detail in my cross re:Eerenced copending application~ . Complete ~enting or 0 psig in the c~-inc~er 14~a will ob~riously :Eully open the eauctor nozzle. The sel:E-actuaking root valve 102a remai~s closed duri~g mi~ing and is controlled in a manne~ identical to that .
- 20 prev~s~y-dbscribed.
- When it is de5ired ~o mine the other ore stra~a ~y opening mining no~e 46a and closing ~ining nozæle

4.~', ~alve 175a is vented ox partially vented a~d valve 174a is open to the 1000 psig mining system pressure thus closirlg ~5 no~zle 46' and shi~tin~ ~he shuttle ~alve core 252 to the righ~ (Fig. 6). At thi~ ~me branch conduit 25~ w;.~l be closed k~ the ~ore 252, and branch conduit 260 will be open to the eductor nozzle cylinder 148a through ~ passage 262 in ~he shuttle ~alve and the conduit 258, The valve 175a may then be adjusted to vary the control p~es~e to ~ ' ' ~-1069~42 the cy~inaer 148a ~ the eductor nozzle lOOa between abou~
~oo and lSO psig ~hus modula~ing the educ~or nozzle as previ~ously describea.
SEhF ACTU~TING EDUCTOR ~OZZLE
A second embodiment o the eductor pu~p sec~ion 44b proviaing a self-ac~uating form o~ edu~tor nozzle ~OOb is illus~ra~ed in ~igures 7 and B an~ .requires r~o control canduits to the su~ace in order to open an~ close : . . . the nozzle plug 144~ rela~ive to its seat 136b ~Fig_ 8~.
The educ~or nozzle lOOb is sh~f~ed betw~ n its drilling m~ae (a~ which time it is closed) and it5 mining mode ~a~
which time it is ~ully openea) in response to aetectins di~er2~ces be~ween the system pressu~ and the w~ avi~
pressu~e. It will be unders~ood ~ha~ ~his eductor noz~le wil~ be used when modulation o~ the educ~o~ no~.zle i5 not reguired for ~he par~icula~ type o~ gxanula~ ~re bein~
mined~ . .
Since all componen~s o~ ~he appara~us except .
the con~rol system 57b and the educ~or nozzle lOOb are 20. the same as previousl~ aescribed i~ regara to the ~irst embodimen~ of the invention~ only the di~erencesbetween the two e~bodiments will be des~r.ibed in ae~ail. Parts o~
the eductor nozzle lOOb which axe similar ~o those o~ ~he ~ .
~irst embodimen~ will be assîgned the same ~umerals followea by the letter "b".
The eductor nozzle plug 1~4b is bolted to a swivel pla~e 154b (Fig. 7) ana is connected to the upper end o~ the piston xod 156b of a pi5ton 146b that is larger ~han the previousl~ described piston 146 (Fig. 3) in order ~o provide ~uicker opening of the eductor nozzle. The piston .

( ~(~6~04Z
146b is r~cei~red in a cylinder 148b having a flow restrict--irlg ba:f:fle 160b near its lower end. The ~affle is provlded with holes 16~b and is drillea to receive the 10~2r damping portion 158b of the pis~on rod 1S6b.
~s ~he piston moves downwaral~r to its :~ull open position, the lower end 158b o~ the pis~on rod ente~s ~he counter bore. 162b in the base 150b h7hich restric~s ~uid :Elow and limit:s f::he rat~ o~ mov~ment of ~he pisto}? 146b an~ ed~c~tor plug 144b~ The p~ssage 164b i~ ~e base ~50 10 aIld a larger diameter condui~ 180b establishes a f~low passage betw~en ~h~ cavity below ~he foo~ ~ral~re 102b ~ig 8)- and ~he eductor nozzle cylinder 148b~ ~ pipe tee 178b - i~ ~e colla~ait 180:b~ a se~tion o~ ~:~ing 176b, ~a th~ .
ca~y pressu:re control line 56b establls~s c~r~uni~ation 15 between ~3 ca~ ielow the ~ot valve and the ~lin~er 240P~ o the mining nozzie 46b. The minin5 noæzle plug - 243~ is urgea ~awar~s i~s closed position ~ a spring 2 2}~
a~` i-s opened ~hen the ~orce developed by sys~em ~ressure on ~he ou~put side o~ ~he plug 243b is greater tha~ ~he sum o~ spring ~orce ana the *orce aeveloped ~ ~he control pressu~e within conduit 56b and cylinder 2~0b acting on th2 other side o~ the plug ~43b.
The eductor nozzle lOOb di~ers ~rom the nozzle 100 o~ the ~ixst embodiment o~ the invention in ~ha~ a ~5 single spring 266~ rather than two springs~ is disp~se~
between the swivel plate 15~b and the base lSOb.
During arilling, the pressure be~ow the foo, valve an~ in the con~rol lines is nearly the same as system pressure. Since it acts on a much larger area than system pressure it serves to keep eduetor and mining nozzles closed durin~ dxilling in conjurlct.~on wi~h spring ~orces In i~pera~ion oE an apparatus which includes the self~-actua~ing educ~or nozzle lOOb, ~he mining noz21e 46b, ana the ~Eool: valve 102b; it will ~e understood tha~ pxior to intro~ucing water into the tool s~ring 36b tFig~ 7) ~ha~
the spring 242b holas the mining nozzle closed, spring 266 holds the eductor nozzle lOOb closed, and the sprins 232:~
hol~is. the f~oo~: valv~s 102b open~ During dri lling~ s~s~em pressure ls abou~: 3~)0 psig and thQ wat:er :E~ ow across the lCI foot val~e is ~bout 1400 gallor~s p~r min~t~ which is insu :~icie~ to create a su:~ficient pressure drc~p across t:he :~oo~ ~ralve ~o close the :Eoot val~re by c~verco~ng ~he pressure ~i~ spri~g 232b~ Thus, during drillirlg the pres - sur~ ~elow the foot valve is close to system pxessure an~t 1~ is directed in~o ~oth cylinders 148b and 240b, This pres--sUre acts on ~:he *ull pis~on area of nozzle plugs 243b and 14~) w~.ile system pressure ac~s on the piston area less t:h~ nozzl~ area, wh~ch is e~posed ~o a much lower ca~ y pxessure~ .
33uring mining, ~he ~oot valve 102~ op~xa~es a~;
previousl~ aescri~ed in regard t~ the flrst embodimen~ o~
the inve~lon. I~ this regard the system pre5sure o~, ~or example, a~out 450 ps.ig and ~low rate o~ a~o~t 1700 gailons per minute across the ~oot valve creates a su~-2S ~icient pressure drop to close the ~oot valve 102b in a controllea fashion through the ac~ion of the.dash pot 203b~
~ce the ~oot valve closes comparatively slowl~, the rela-~ively large area o~ the piston 116b that is exposea to the 450 psig system pressure on one sidef and the gra~uall~
decreasing pressure on the other side, causes the eductor ~;~5_ . .

'. . . . . .
.

;
10~ 9,z nozzle plug 144b to at least~ s~s tan~ially open prior to the foot ~ralve closing against the urginy of ~he sprilly 232b. The crea~ion o~ a low pressure below ~he foot valve and the ~ransmission of low cavit~ pressur2 to the .: 5 cylinder ~40b of the mining nozzle 46b thus pex~i~s s~stem pressure .o :Eully open ~he mining nozzle 46b agains~ the urging o:E sprirlg 24~b~ --- ~OOT VAI.~: W~T~ SEr,F-C~ING ~SE Pt}T ~D
- SE~--ACTIU~I!I~G l~Oi~--MODU~T:~G CQ~TRC)l; SYSTE~
A ~hira emQ30di}nent o~ the educ!tc)r pump ~:ec:tion 44c and control system 5~c is illustrated in E~igu3ces 9 and 10~. Thi~; section is similar tc~ th~ firs~ e~ibod~e~t o:E
he in~ention and di~ers primaril~r in tha~ cyli~der ~04~
.. o th~ ~h pot 203c i5 inverted and is an integx21 ~or~ion ; of ~he plug 214c o~ the fopt val~ 102c. Thus, o~ly the di~eren~es be~wee~ the two embodLments will be descr~e~
in de~ai~ and par~s o~ the third ~mbod.umen~ that are . s~m~ ~ to.the ~irst emboaimen~ will be assigne~ ~he same numerals f~llowea by the letter "~".
Tha valve se~t 136c of the eductox nozzle lOOc re~eive~ an eductor nozzle plug 144c that has ~uide fi~
270 on i~s ou~er periphe~ and has a p~s~on 272 fo~mea o~
its lower en~. The piston 272 is slidabl~ received in a ~ylinaex 274 having a flanged base 276 that is rigid~y secuxed to the ~lange 116c by capscxews and spacexs ~78_ ~5 A compression spring 280 is disposed between the ~wer wali - .282 o~ ~he cylinder 274 and ~he upper wall of a cavi~y in the eductox nozzle plug la4C~ and urges the eductor nozzle plug 144c ~oward its closed position~
A con~rol conduit 283 ~s connected betw2en ~he ~ LQ69042 cyli~e~ 240C ~Fi~. 10) of the mining nozzle 46c and ~he eductor nozzle cylinder 274. The base 276 o~ the eauctor nozzle lOOc is apertured to receive a ~ube 284 rigid ~here with and projecting downwardly therefrom~ The lower end of the tube 284 is opene~ to pressure below the ~oo~ valve and accordingly directs this pressure into both the eductor nozzle cylinder 274 and the mining nozzle c~linder 2~0c when the ~Qo~ valve 102c is clo~ed~ The da~per ~isto~ ~18c is secured to the tube 28~ by snap xings or the like an~ is pro~iaed with a biee~ passage 230c.
~ s mentioned a~o~, the aas~ po~ ~ylinder 204c is.inverted rela~ive to the dash po~ o~ the ~irs~ e~bodi-men~ o the ~nventio~. The cyli~der 204c has a cap 222c. wi~h a bleed hole 228c therein bo~ted to the c~llnder and is centrally aperturea to sliaably receive the tube 28~.
The 5pring ~32c is disposed between the cap 222c and the .
piston ~18c and normally urges the foot ~alve ~2c to its -open posi~ion~ The lower end o~ the cy~inder de~ines ~he ~oa~ valve p~ug 214c which i-~ provlae~ with a large diame~ex central port 286 ~hat esta~lishes ~ree co~munica~io~
~e~ween the cavity helow ~he ~oot an~ the interior o~ the c~lin~er 204c below ~he piston 218c, The foo~ valve plu~
214c includes guide vanes 216c which are receivea in the '~-.
port of.the valve seat 200c that is securea to the ~lange 184c to which the tubular dxill bit 38 ~ig. ~3 is securea.
Thus, whe~ the foot valve 102c is open as illus~a~ed in Figure 90 water is di~ected be~ween the guide vanes 216c~
through the foot valve seat 200c and through the tubular drill bit 3~ into th~ well cavity being drilled, When the foot valve moves downwaraly into the closed position, the .

~06~Z

major flo~ o~ water is prevented fro~ entering .ha cavi~y and is split to flow through the educ~ox nozzle lOOc and " - the mining nozzle 46c (Fig. 10) bo~h of which are open at this time.
~s .illus~rated in ~igure 9t as ~he ~oo~ e moves downwardly the ou~er peripher~ of the damper pis~on 218c is progressivel~ movea wi~hin the large dia~eter - ~ylindrlcal bore 220c, the ~usto conical bore 224c, a~
: the small aiame~er bore 226c thereby progressivel~ ~no~as-~o ing ~he resistance ~ the ~low o~ water across ~he pis-ton and progressively reduces the r~ of closi~g ~o~me~ o~
th~ ~o~ valve. -Since the tube 284 is positioned coaxially wi~hinthe inner condui~ 50~ and the outer condui~ 52c o~ ~he.
tool string 36c, the spacing hetween t~e eductor nozzle lOOc and the ~oot valve 102c is mu~h less than ;n the previously describea embodiments of the inve~tion, ~lsov the ~].ange 184c is connected ~y screw ~hreads ra~her ~han by bolts to ~he outer pipe secticn S2c, which threade~ connec~lon i5 ~o a much faster and less expensive ma~ner o~ ~onnecting t~e componsnts together.
In operation of the eductor pump sectîon ~c an~
~ the mining nozzle 46c of the ~hird embo~imen~ o~ the inven~ion, reference is directed to Fi~ures ~ and 10 During drilling, a~out 1400 ya~lons per minute o~ waier at a system pressure o~ about 300 psig is directed~e~w2en the inner ana outer pipe sections 50c~52c an~ through the foot ~alve 102c into -~he well cavity. At this tîme the pxessure drop across the f~ot valve 102c is insu~icient to reauce the pressure below the foot valve eno~s~. to _28-- \
"` 1~6~42 ov~rcom~ the resilience o~ the dash pot spring 232c, the eauctor no~zle spring 280, or the mlning nozzle spring ;'.......... 242c~ Thus, during drilling the ~oo-~ valve remains open and the e~uctor nozzle and mining nozzle are boLh held closed by spring ~o~ce and fluid pressure ~ t the start o~ mining~ the capacit~ o~ water is increased to abou~ 1700 yallons per minu~e and the pxes~
sur~ is increased to a sys~em pressure of abou~ 45~ psig~
The increased ~low o~ water ~hro~gh the ~oot valve 102c increa~es the pre5sure drop a~ross the ~oo~ valv~ enough.
to ~ause the foot val~e to move d~wnwardl~ again5~ t~e urging o~ ~he spring Z32c. As the foo~ valve closes, the . .
: pres~ure below ~he ~oot valve is reduced enough, compa~ed . to ~he 450 psig system pressure, to allow s~ste~ pressure .
- 15 to o~rcome the ~orce o~ the springs 280 and:242c thus opening the eductox nozzle lOOc and the m~ning nozzle 46c_ The ~ate at which the ~oot ~alve 102c is allowed to close- i5 controlIed by the dash po~ 203c. Since the water within the dash pot must ~1O~Y between the piston 218 (Pig.
2Q 9~ and the inte~nal surface of ~e c~lindex 204c in ord~r for the foot valve to close~ t~e gradual decrease in ~lo~
passage si~e, as determined ~ the surfaces 2~0c, 224c and 226c, as ~he cylinder moves downwardly results i~ a co~trolled closing of the foot valve in the face o~ in~
creasing pressure drop across the valves. During fina1 closing of the foot valve, ~he water wi~hin the cylinder above the piston 218c must ~low ~hrough bleed holes 230c and 228c.
As the foot valve 102c closes, the educ~or nozzle lOOc and mining nozzle 46c begin to open. Since the _~9:

, , . : , ~06~42 c~lina~rs 2~4 ~nd 240c are both filled wi th water which mu~t be displaced ~efore the nozzle plugs 144c ar~d 2 3c can ~?en, it is apparent that the relativel~r sma~ll passages in -~he tube 284 and conduit 283 t~ll restrict rate o~ flow o.~ [uid there~.hrough~ Thus, the size of tl~ese passages may be selected so as to control the rate o:E opening of the e~ctor no2æle lOOc and minlng noæzle 46c ~o -~erë~y reduc~ water ha~ner to ar~ acceptable deg~ e~.
I~ will be a,~precia~ed tha~ ~uring mi~ing wh~n the foo'c valve 102c is closed, a small amc:~u~ ~ er will :~low through blee~ passages 228c: and ~!30c into ~h~3 well c~vi~ therebelow thus tendins ~o maintair~ 'che das~
po~ 203c :~ree :Erom sand and dirt ox the 1~ Likewise, w~en .
the i~ot ~al~re is open, any co~taminates ~hat enter the ~ dash pot ~11 be flushea there:erom into the well cavi~r - - ~hrough the relativel~ large annular openin~ defined be ~ween ~he ~uter periphery of the piston 218c an~ the por~
:~ 220c. This water and d~bris then ~lows th~ough opening 286 in~o th~ well cavit~. .
F~OT UALV13 WIT~ SELF-C~:i:NG DASH POT
MODUL~T~NG COI~ROL SY5TF~
~ :Eragmen~ o~ a ~ourth em;bodiment: o:E the educ:tor pump section 4~ is illustxated~ igure llo ana is identi-ca:t to the third e~r~od.iment e~cept that the ~auc~or noz21e lOOx is de~ignad so that it may be modula~ed. Thus, only the dif~erences will be described in detailO and componen~s o~ the eauctor pump section 44x that are e~uivalen~ ~o the eductor pump section 44c will be assignea the ~am~ num.erals followea b~ the letker x~
The eductor nozzle lOOx incluaes a flanged base ~ 69~
276~ that is thicker than the base 276 (Fig~ 9) and has a passage 324 therein that estahlishes communication between-~on~rol conduit 283x leading to the associated minin~ no2zle ana the -tube 28~x o~ the foo~ valve 102x w~ich communica~es with cavi~ pressure when the foot valv~ is closed. ~t is ; particularly noted that the eductor no2zle cyllnder 27~x does no~ communica~ through the tube 284~ to ca~ity pressure, - ~ut insteaa is connec~ed to a con~rol llne 326 ~ a port 3~8~

1~ Xf sur~ace control i9 desirable~ the educto~ pump section 44~ is substi~ut~d for the pump sec~o~ ~4 ~Fig. 5 ~- ~r ~4~ (Fig~ 6~ and is con~rolled ~ co~tr~l systems simi-l~r to those dPscri~ a in con~ctisn with ~igures 5 an~l 6.
The resulting opera~ion o~ the pump sec~ion 44x is su~_ . 1$ stantially the same as describe~ in those s~stems, In thi~
regar~, co~duits 3~6 and 283x are connected to condult~
1 ~4 and 56, respectively, if a control system similar to t~e~syste~ illustra~ed in Figure 5 is used, and are con-nec~ed to control lines 54a and 5~a respec~ivel~ i~ the Figure 6 sys~em is to be used~
CONTRO~ SYSTEM ~OR MO~ULATING ~DUCTOR
NOZZLE WITXOUT CO~T~OLS TO THE SURFACE
: In Figura 12 a h~araulic control system 57d is illustrated ~or modulating the eductor nozzle 100 during mining wi~hou~ requiring special control lines ~o the surfa~e. Although the control system 57d~L11 be describea in relation to the previousl~ described components o~ the ~irst emb~dimPnt o~ the invention, it will be understood that such control system ma~ also be used with the fourth embodiment o~ the invention if ~esired.

~69042 Since the mining nozzle 46, eductor nozzl~ 100 and :foot val~re 102 are the same as described in the :Eirst enibodimen~ o~ ~he invention, only the modulating oon.rol s~stem 57d will be described in detail, and par~s o_ ~:he

5 sys~em 57d tha~ are ~quivalen-t to the s~stem 57 will be assigned ~e same numerals ~ollowed by the letter "d".
The control system S7d comprises a pilo~ actua~
- proportionirlg valve 302 having a core 304 therei~ w~ich is held în ~he illustrated position by a preloaded spring 10 306 when s~rstem pressure is below the drilli~g pressure o:E be~ween about 300-400 psig. When in the illus~ra.ed drilling `posltion,~ sys~em pressure SP in th~ tool string 36 (Fig~ 1 and 2) acts throu~h a conduit 307 Oll ~he upper .
end. of the core 304 tendin~ ~o move it downwardl~. This 15 force i~; counteracted ~ he :Eorce of~ the spxing 30;~i plus Ikhe pressure ~elow the ~ o~ valv~ 102d, which pxessure is su~stantiall~ system pressure and is conmunicated to ~he other end oi~ ~he prop~rtiorling va~ve 302 b~ a conduit 308.
A branch conduit 310 connet!ts ~he pressure conduit 308 -to a port 312 in the valve whic~ at this tlme is ~losed by $he core 304. ~Lmilarl~, the system pressure coEduit 307, which is connected to the water suppl~ a~ a poi~t , abo~e -the ~oot valve is connectea by a b~an~h co~duit 313 to.a por~ 314 in the valve and a passage 316 throu~h the core 304O The passage 316 is connected to the e~uctor noæzle cylinder 148d by a conduit 318 while the mining nozzle cylinder 240 is connected below the ~oo~ valve by a conduit 320. Thus~ when the system pressure is app~oxi-mately drilling pressure, that pressure is also com~uni-cated into cylinaers 148d and 240d thus holding ~otn the ~06~4Z
eductor nozzle lOOa ana the mining nozzle 46d closea- The sel~-activating foot valve 102d will be ope~ during drillin~
as previously described.
- As sys~m pressure is i~creased to full mining pressure o~ for example, about 1000 psig, ~he ~ot val~e 102d is closed as previously described resulting in cavity pxessure below the ~oot valve. Th~ 1000 p~i~ sys~em pre5sure also enters the condui~ 307 and shi~ts the core 304 to the o~her end of i-~s stro~e ~ which ~ime a passage 32Z in the core comm~nica~s wi~h por~ 31~ and ~onauit 318 thus ven~-ing the eauctor nozzle c~lin~er 148a ~o ~he very low cav~y . pressure~ The.mining nozzle 2~0d is likewise vented ~o cavi~y through condui~ 320. The high system pressure act-in~ on th~ educ~or nozzle and the minlng nozzle ~he~ over~
comes the c~i~y pressUre plus the pressure applied by spr.in~s 16~a, 170d and 242d to full~ open the eductQr noæzle lOOd and the mining noz~le 46d~ .
~odula~ion of ~he educ~or noæzle lOOd is accom~ :
plished ~ selecting and preloading the proportioning vaive spxing 30~ so~tha~ i~ will cause the val~e to shi~ :
~krough its entire modulating rang~ in respo~se to a system - pressure va.riation o~ about 50 psig~ :
For example~ if the mo~ula~ing range of the ~ozzle is 40 percent, i.e., 60 percent ope~ to fully ope~ as previously describedp an~ if 1000 psig is ~he maximum mining system pressureO variatio~s of sys~em pressure between 950 and 1000 psig will cause the eductor nozzle lOOd ~o modulate thxough its entire 40 percent range. Xn accordance with ~he above example, it will be apparent -~hat when the system pressure is 950 psig, the proportioning valve 302 t~ill be ```` ~6904~
par~ially opened an~ the swivel pla~e 154d will be contac~--ing the hea~ spring 170d .. Ii~ the system pressure is in--creased to 975 psig or example, ~he heavy spring 170a is .
.
compressed until th~ force devel~ped b~ sys~:em pressure ac~ing do~wardly on the upper sur:Eace o~ the pis~o~ 1 6d is equal t:G the sum o:f the forces of the springs 167dt 170d an~ the force developPd by the control pressnre wi~n ~he - c~linder 148d, which cylinaer pressure is c:ontrolled by the ~ralve 302 to lie between ~yst~em pressure and ca~ri~r pre~
sure. Thus, each pressure setting hetween 950 and 7000 psi~
will cause the eductor nozzle lOOa to open di:~erent amounts.
~he sys~em pressure received :Erom pump P ~Fi~. 1) may be ~raried J~ adjusting a valve 82 in the water inlet: condui~
~4, or by varying the speed o:E the pump P~
. It will be u:~derstood that shi~ki.ng the pro~
pDrtioning pilot ~alve 30~! by var~ing the syste%r pr~ssure :~ through ~he 50 psig modulating range h~ill cause the pro-p~rtlc)ned pressure entering ~he educ~ox nozzle c~lin~er 148d to ~ax~ between about 150-500 psi~, 2 0 DUAI. MIN:i:NG NOZZ~E CO~RO~ S~S~EM
WITEt:)UT SU~ACE CONTE;~OIS
A hydraulîc co~rol system 57e is diagramm~ically illus~ra~ed in Figure 13 ana is designe~ ~or use with a mining and drilling apparatus having two min;ng nozzles 46e and 4G". The control systern 57e is sel:E-activating~
includes no control lines to the sur~ace~ and is capa~le o:E bo~h rnodulat illg the eductor nozz:Le 10Qe and also selec~--ively opening and closing the mining nozzles ~G~ and 46~' in ~esponse to selective variations in the system pressure~
The eductor ~odulating portion 57ae o~ the control -34- .

069~4;~

system 57e is struct~rally ~he same, and i5 operated in the same way, as the modulating control system 57d illus-trated in Figure 11 except for the points at which the nozzle 46e and 46" are connected into the system 57e of :
the control system 57e will not be described in detail and parts o~ the system 57de which are equivalent to those o~
the system 57d will be assigned the same numerals followed by the letter."e".
~he control system 57e includes condui~s 332, 10. 334 ~ommunicating wlth system pressure SP at a point in the outer water supply conauit 52 (Fig. 2)~ Conduits 336, 338, 340 and 308e are connected to vents V or the pres-~ure existing at a point below the foot val~e 102e, which pressure is substantially s~stem pxessure when the ~oot valve is open and is cavity pressure when the foot valve is closedO
A~ter the arilling operation has been completed and the apparatus 30 (Fig. 1) is assembled in i~s mining mode, the pump P is started and d.irects water through the 20 valve 82 and conduit 84 into the ou~er annular passage . .
defined between the outer conduit 52 and inner conduit sa o~ the tool string 36. .As the water pressure withi~ the conduit 52 reaches khe mining system pressure o~ for example~
about 450 psig and is ~lowing at a ~te o~ about 1700 gal~on~
per minut~, the fuot valve 102e (Fig. 12) closes and the ~ductor nozzle lOOe ~ully opens as previously described in reyard to the contnol system 57d (Fig. 12). During this time the system pressure SP enters conduits 332 and 334 causing proportioning valve core 304e to move downwardly against ~he urging of spring 306e th~eby venting eductor -, , , ' 1~69~42 nozzle c~linaer 148~ to cavit~ through passages 318e, 322e, 310e and 308e.
S~stem pressure SP is also directed ~pw~rdly through a conauit 3423 a paxallel passage 3~4 in the core 346 of a shut~le valve 348 and through con~uit 350 into the cylinder ~40" of the upp~r mining nozzle 46" th~by holding the upper mining nozzle closed. A~ thîs tlme the cylinder 240 of th~ lower mi~ing nozzle 46e is ~en~ed to cavi~ t~xoug~
- a conauit 352, parallel passage 354 in cvre 3~6, co~duî~

10 356 and ~he conduit 308e to the well cavit~ -~he high pressure li~ui~ whi~h entexs cona~t 33~ a~ system pressure SP initiall~ ~lows thr~ug~ a passage 358 in the core 360 of a valve 362. The high pr.essur~
.~quid -then flows through a condui~ 364~ a parallel passa~e 366 in the core 368 o~ a valve 3700 and t~ough a cond~it 372 into one end of a ~alve 374 ~avln~ a core 3 76 therein. The core 376 is connected to the ~re 346 o~ ~al~e 348 ~ a link 37~ High pres5ure li~ui~ enterins : the en~ o~ the valve 374 ~hen shifts the cores 346 and 376 20 f.rom the illustrated positions to the le~tO Shif~tlng ~he ~ore 3~6 Prom its parallel passaye position ko .its Cross passage posi~ion clo5es lower mining nozzle 46e by directin~
high pres.sure liquid into the c~linder 240e throug~ crc3ss passage 380, and opens the upper rnining nozzle 46" by 2~ ~enting cylinder 240" to cavity pxessure through a cross passage 38~.

Shiftiny the core 376 to the left peroxms no function until the core 360 of valve 362 is fully shi~ted to $he left~ In this xegardO high pressure liquid entering conduit 332 flo~s through conduit 384 into the right end -~6-~ ` i06~42 o~ the valve 362 thUS s`lowl~ shifting the core 360 to ~he le~t again~t the urging of a spring 3~6. The co~dult 336 which ven~s the o~her end of the valve 362 to cavity pres-sure includes a ~low resisting valve 38% thxough which ~e water in -the lef~ end of the valve 362 must flow be~ore the core 360 can shift full~ to the leit~ The flow resis~ing valve 3~8 is.adjusted to slow the rate o~ movement o~ the core 360 su~icie~tly to peXmlt all o~ the above aescribed functions ~o.occur before the core shi~sr 10- . A~ter the core 360 shi~ts to ~he lef~, hiyh pressure liquid ~lows through a passage 390 ln the core 360~ a condult 392g para~1el passage 394 in shl~ted ~oxe 376, and condult 396 to the righ~ end o:f~ the valve 370 thu~ shifting lts co~e 368 to the lef~. The li~uid in the 1~ other en~ of the ~alve 370 is vented ~o the w~11 cavity through condui~ 398, parallel pas5age 400 in the ~ore 376 ana conduit 34~. Shifting of ~he valve core 368 has -no immediate e~ect o~ the mining nozzle 46" and 46e~ bu~
preset~ the control system 57e to shi~t the mining nozzle upon reducing ~he ~ystem pre5sure below ~he ~or~e pres~
sure o~ the spring 386 As mentioned previously în regard to the modulat-;ng cont~ circuit 57d illustrated in Figure 12, modulation o~ the eauctor nozzle is pre~erably accomplished by varying the system pressure wi~hin ~he range of bekw~e~ about 950 to 1000 psig. The pressure o~ spring 3~6 which controls ~alve 362 is preferably set to balance a system pressure of about 900 psig thus permit~ing ~ull modulation o~ the eductor nozzle lOOe without effec~ing the valve 362.
~hen it is desired to open mining nozzle 46"
-37- :

~06~42 and close mining nozzle 46e, -the syste~ pressur~ is rcduced to slightly below 900 psig by throttling valve 82 (Fig. l)_ ~he spring 386 (Fig. 13) thus returns the valve core 360 ~o its illustrated rig~t hand position and sys~em pressure,is the~eafter increased to ~e desired mining pressure b~ open-ing c~ntrol valve 82 ~Fig. 1). High pressure fluid ~hen ~lows through conduit 332 (Fig. 13)~ pas5age 358 in ~e ~ valve core 360, conduit 364, a cross passage 404 in t~e cor~
36~, and a conduit 406 to the left end o~ ~he valv~ 374 whic~
re~urns both coxes 376 and 346 ~o their illus~rabd positiQ~s.
Shifting the core 376 to the rig~t causes low pressure li~Uid to be vented from the righ~ end o~ the ~a~ve 374 through the co~duit 372, cross passage 410 an~ conauit 338 to ~he well cavity. Shifting t~e core 346 to the illustrated p~ ion opens mining no~e ~6e and closes mining nozzles 46"~ as previously described. As the pressu.re rom lines ! 33.~ and 384 again shi~t the core 360 to the left, high pressure liquid :Elows from conduit 332 ~rough passac,re 39()~
conduit 392, cross passage 414 in the cc~re 376, and condui~:
398 thus shifting ~alve core 368 to its il~ustrate~ righ~
hand position. ~t this time li~uid in the ri~ht end of ~he val~e 370 is vented thrOEug~ conduit 3~6, a ~ross passage 416 and ~he conduit 340 to ca~ity.
Thus, the above procedure is repeated each tLme the system pressure is dropped below 900 psig and there-after returned to mining pressure~ DurLng mining~ the eductor nozzle lOOe rnay be modulatea as desired~ withou~
affecting the mining nozzles.
. When system pressure is xeduced to 0, the foot valve 102e is opened by the spring 232e, the eductor nozzie . -38- .

.

`r ~ ( 69~Z
lOOe is close~l h~ springs 167e and 170e, and ~o.h mining nozzles 46e and 46" are closed by springs 242e znd 242 ~ lthough the control sys~em 57e has been de~
scribe~l in conjunc tion W.it~l a modulating educ~or nozzle, 5 it will be understood that the uppç~r portion o:~ ~.e sys~em 57e may be used independently of tne modulating sys'em 57de~
I~ used in- in ~his way~ the conduit 342 would comm~icat~ w;~h - systeIQ pre sure and the conduit 356 would commu~ a~e with ca~ y. In such a system, any of the he:rein described 10- eductar no:~:z:le~; and foo~ ~ralve~ could be used, ~3 the educ~or no~21e could be cor~trolled b~ a self-activa~ed sys~em s~milar to Figure 8~ or ~y a sy~em havirlg a co~2t:rc.3 . ~ . line tv ~e surfac~ such as cont:rol line 54 (Fis. 5~
. From the foregoiny descrip~ion i~ will be 15 ~pparent that the arilling an~ minin~ appaxatuq o~ e presen~ invent~on includes several modi:Eîed ~arms. o~ -eductor pump sections wherein the foot ~al~e i~ self- -activa~ing in response to the rate of Xlow of.liquid th2re~hrough. The foot valve is operated ind~nden~ly .
of ~he edu~or nozzle and includes a das~ pot whic~ reduces the ra~e of clo~ure of the foot v~lve ~o minlmize "wa~er hammer" which'rwater hammer" is ~urther minimized by allow-ing ~he eductor nozzle to at le~st partiall~ open prior to full closing o~ the ~oot valve~ Several h~araulicall~
opera~e~ con~rol systems axe incluaed i~ the inven~ion and permit modulation of the eductor nozzle .when either one or two mining nozzles are being used withou~ effecting the position of the mining-nozzle ox nozzles.during modula~ion~
When two mining nozæles are being used, the co~trol s~stem is effective to open only one mining nozzle at a time ~ .
` ~069~42 The several h~dxaulic control systems ma~ either includ~
separate control iines to the surface, or may be sel~-- energizing and be devoid o~ control lines to t~e sur~ace.
In all control sys~ems, the pressure involved are equal 5. to or less than mining system pressure ~7hich is bet~een about 700~1000 psig in the illustra~ed preferred e~odiments.
Also, eaeh control system is capable of adjustin~ the sev-~eral opera~ive components of the ~rilling and mLni~g ap-; . paratus betwee~ t~e drilling mode and mining mode withou~ .
withdxawing ~he tool string ~rom the well cavi~y~ Xn all configurations controL pressure assists in holdirlg the eductor and mining nozzle~ closed.aurins drilli~g.
Although the best mode contemplated for carryix~ .
out ~he present inYention has ~een herein sbown and de-scribed, it will be apparent that modi~ication and varia~ionmay be made without departing from wha~ is regarded t~ b~
the su~ject matter o the invention, ;~: lw _40 .,

Claims (7)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A foot valve positioned between a first pressure zone subjected to variable system pressure and flow rates and a second pressure zone which pressure varies from slightly less than system pressure to cavity pressure, depending upon the flow rate and position of the foot valve cavity pressures therein comprising; an apertured valve seat for establishing fluid communication between said zones, a valve plug movable between an open position permitting flow of liquid through said valve seat and a closed position at least substantially terminating flow through said valve seat, a dash pot disposed in the first zone and associated with said plug to reduce the rate of closure of said plug; said dash pot including a housing communicating with said first pressure zone through bleed passage defining means for allowing liquid to enter said housing, a piston rod slidably received in said housing, a piston connected to said piston rod and disposed within said housing, resilient means disposed between a portion of said housing and said piston for urging said foot valve plug toward its open position, and means defining a bleed passage extending from one side of said piston to the other.

2. A foot valve according to claim 1 wherein said piston has a cylindrical periphery and is progressively aligned with a relatively large diameter cylindrical surface, a frusto-conical cylindrical surface, and a small diameter cylindrical surface of said housing as said foot valve plug is progressively moved toward its closed position, the space between said piston and said surfaces defining said bleed passage.

3. A foot valve according to claim 1 wherein said resilient means resists closing of said foot valve when the flow rate across said valve is less than about 1400 gallons per minute and is under a pressure less than about 300 psig, and closes due to an increased pressure drop across said valve when the flow rate is increased to about 1700 gallons per minute at about 450 psig.

4. A foot valve according to claim 1 and addi-tionally comprising a bleed passage through said foot valve plug to provide a low capacity flow of liquid into said second pressure zone when the foot valve is closed.

5. A foot valve according to claim 2 and addi-tionally comprising means defining a bleed hole through said piston.

6. A foot valve according to claim 1 wherein said piston rod is connected to said valve plug and moves therewith.

7. A foot valve according to claim 1 wherein said housing is rigid with said foot valve plug and moves with said plug relative to said piston during opening and closing of said foot valve.