US 2251916 A
Description (OCR text may contain errors)
Aug. 12, 1941. R. CROSS WATER MINING SOLUBLE MATERIALS Filed June 12, 1939 3 Sheets-Sheet 1 FROM PUMP INVENT OR.
Aug. 12, 1941. CROSS WATER MINING SOLUBLE MATERIALS Filed June 12, 1939 3 Sheets-Sheet 2 INVENTOR. E0 0056, BY
Aug. 12, 1941. CROSS WATER MINING SOLUBLE MATERIALS Filed June 12, 1939 5 Sheets-Sheet 3 m z i INVENTOR. Jiqg r056,
Patented Aug. 12, .1941
UNITED STATES PATENT OFFICE WATER MINING SOLUBLE MATERIALS Roy Cross, Kansas City, Mo.
Application June 12, 1939, Serial No. 278,663
This invention relates to solvent mining of subterranean deposits of underground materials for the recovery of soluble materials. It relates more particularly to the mining of potash salts from subterranean deposits thereof.
This application is a continuation-in-part of my earlier copending applications Serial Numbers 136,178, now Patent No. 2,161,800. June 13, 1939, and 267,506. Potash minerals such as sylvinite, langbeinite, kainite, polyhalite, etc., often lie in comparatively thin beds and the vertical thinness of the bed presents difliculties in obtaining circulation of the solvent introduced into the deposit in such a manner so that the interfacial saturated or super-saturated layer of solution will be carried away from the face of the mineral being acted upon. An object of this invention is to overcome that difliculty.
In the present art of mining common salt by water, it is known that extended contact between the water and the face of the salt must be provided. For example, in the mining of sodium chloride in Kansas it is known that when water is introduced to the bottom of a salt bed several hundred feet in thickness, that the solution does not become saturated until the salt has traveled upwardly across the face of the rock salt for at least 75 feet. The requirement for horizontal A circulation, however, is not present in the art of mining sodium chloride because of the extreme thickness of the beds and the fact that too much horizontal circulation causes caving. To prevent this, salt wells are operated so that they will not have a diameter which exceeds approximately 200 feet.
The mining of potash salts presents a different problem in that the thickness of the beds ranges from a few inches to about 14 feet maximum. Furthermore, the mining of potassium chloride from sylvinite ores, as described in the aforesaid patent applications. leaves something of a reticular mass of sodium chloride crystals which presents resistance to horizontal circulation. Another object of this invention is to overcome this difliculty.
It is well known that although a substance is soluble in a solvent its rate of solution may become almost .infinitesimally slow, even though the solutes be finely divided, unless the mixture is stirred. It is equally well known that if a lump or chunk of solute is placed in the bottom of the receptacle and that receptacle filled with solvent and heated, that solution takes place very slowly and finally nearly ceases due to the lack of circulation which would bring unsaturated solvent into contact with the solutes. A similar problem arises in mining potash with a solvent solution.
The seriousness of the problem overcome by this invention may be appreciated if a bed of potash salt such as sylvinite having a thickness of 7 feet and lying at a depth of 1000 feet is considered. Whether the solvent be put into the top of the bed or the bottom of the bed, it will be seen that the tendency of the liquor is to bypass into the outlet before becoming saturated. This difliculty is overcome by this invention in a number of diiferent ways. The principle underlying all of these means is that a substantial horizontal component of circulation of solvent shall be established in a pool of dissolving liquor acting upon the .mineral to be dissolved. The economics of mining subterranean beds of salts where the beds are thin are greatly affected by the ability to maintain horizontal circulation as set out. For example, the amount of salt dissolved by operating one well must be suiiicient to bring a price which will justify the investment in the well and equipment. Otherwise, the bed cannot be counted as a reserve of natural resources. Thus, another object of the invention is to make available valuable resources whichwould otherwise be unavailable.
Other objects and advantages of the invention will be apparent by reference to the following description in conjunction with the accompanying drawings, in which Figures 1 to 11, inclusive, represent various means and modifications by which the objects of the invention may be accomplished.
Figure 1 illustrates one of the simplest ways of accomplishing my invention. It will be noted that solvent is introduced substantially at the top of the bed and by pressure in the downcoming pipe is given a horizontal component directed toward the walls of the cavity containing the pool of solvent liquor. In this modification of the invention, advantage is taken of the fact that as solvent passes in contact with the mineral bed, its density increases and a natural circulation downwardly is obtained. The saturated liquor is removed at the bottom of the bed and travels upwardly in the production pipe I, the outlet of which is under lower pressure-than the inlet pipe. The casing 2 permits the unsaturated solvent to be pumped downwardly by suitable means and thence laterally through holes 3 into the dissolving pool of liquor.
In Figure 2 is illustrated another means of accomplishing circulation across the face of the as will hold its cable in tension. By this means a pool of saturated liquor may be quickly obtained. It is desirable to have a screen I which surrounds the propeller and a fin 3 which will give the unit an upward tilt so that a horizontal component may be established in the pool of liquor. A casing 3 permits introduction of an unsaturated solvent liquor downwardly by suit.
able pumping means It. The saturated liquor flows upwardly through production pipe II and thence to suitable precipitating or separating equipment. A drum l2 provides means of controlling cable 6.
In Figure 3 another means of accomplishing a horizontal component of circulation in the dis-.
solving pool is illustrated. In this figure, a casing I3 is set on top of the salt formation. Unsaturated liquor is introduced into the salt bed through pipe I4, having-attached to its bottom flexible tube l5. The tube I5 may or may not be equipped with a nozzle IE to give a high velocity to the dissolving liquor. The cable [1, controlled by drum I8 at the surface of the ground, is arranged to hold the nozzle in a substantially horizontal position so that a horizontal circulation component may be obtained in pool [9. In this modification of my invention, unsaturated brine forced downwardly by suitablepumping means through a tube l4 and a flexible tube l5 cir-.
' culates across the walls of the cavity and thence upwardly in a pipe l4 which is preferably insulated. From pipe l3. the liquor proceeds through an outlet 2| to suitable precipitating means above ground.
Figure 4 shows another modification of the invention. In this operation, unsaturateddissolving liquor is forced by pumping means 22 downwardly through inlet pipe 23 into a pool of dissolving liquor 24 which acts upon salt bed 25. Nozzle 26 is inserted in the lower extremity of tube 23 so as to give a high velocity horizontal component to the liquor traveling therethrough. Tube 23 is preferably rotatable so that horizontal travel may be had in all directions. Altemately, a number of nozzles pointing in different direc-' tions may substitute for single nozzle 25. The brine is released from the pool through production pipe 21 and is carried thence to suitable precipitating means. A casing 28 is set on the top of the formation. In this modification the casing 28 is airtight at its top and the liquid level caused by pressure in the dissolving pool is thereby limited upwardly.
Figure 5 shows an electrically driven device to secure horizontal circulation and at the same time cut away residue salts not dissolved by the dissolving liquor. In this modification of the invention, dissolving liquor is pumped by pumping means 29 through inlet tube 30. To the bottom of inlet tube at is attached flexible tube 3| and to its lower extremity is attached electric motor 32. A suitable cutter 33 is attached to one end of the motor shaft and a propeller 34 to the other end. The propeller 34 rotates in such manneras to drive the cutter forward against the face of the mineral bed 35. A cable 35 is controlled from the surface of the ground by reel 31 and controls the level of the motor mechanism in the pool of dissolving liquor 38. The brin the saturated solution travels to suitablev precipitating means such as shown in application Serial No. 267,506.
Figure 6 shows still another modification of v the invention. Brine is pumped by pump 4| downwardly through tube 42, flexible tube 43, and turbo cutter 44. When passing through the turbo cutter its pressure forces the cutter to rotate in order to penetrate solid residue left in the pool of dissolving liquor 45. Cable 46 is controlled from the surface by reel 41 to hold up the end of tube 43 so that horizontal circulation can be accomplished. Sliding spacer 48 rests on the lugs 43 on the bottom of casing 50 which has been set on the top of the salt bed. Guide 5| carries cable 43 so-that it can not twist around pipe 42 and thereby become inoperable. The brine having passed across the face of the mineral bed 52 circulates upwardly in casing 50' and is exhausted to suitable precipitating means.
Figure 7 is an enlarged drawing of turbo cutter 44. The pressure of fluid traveling through holes 43 rotates the helical element 53 which is rigidly attached to cutter 54, the shaft of which is held in bearings 55.
Figure 8 shows another means of obtaining horizontal circulation. 56 is a casing set on top of mineral bed 51. Dissolving liquor is forced by suitable means through flexible tube 53 and turbo cutter 59, the details of which have been heretofore described. It is obvious that the turbo cutter need not be attached to flexible tube 53 unless a solid residue is left as wouldbe the case in mining potassium chloride from sylvinite with a solution saturated with respect to sodium chloride. The brine serves to turn cutter 53 and at. the same time furnishes suflicient horizontal component to gain circulation across the face of bed 51. Thence it travels upwardly through casing 53 and thence to suitable precipitating means. The cylindrical element 50 is substantially open at the bottom and has holes in the sides through which dissolving liquor can circulate. In element 60 there is a curved guide 6| which serves to give the flexible tubing 53 a horizontal direction when it is forced through rollers 62 and 63. Lugs 54 are attached to element 50 and co-act with lugs 55 attached to the bottom of the casing to prevent element 60 from descending completely into the pool of dissolving liquor 65. The cable 61 is controlled above ground by a suitable reel which serves to hold the end of the turbo cutter or cutter 53 or flexible tube 58 substantially horizontal. The cable runs over pulleys 68 and 59 so that a considerable angle of the pool from the center line of the turbo cutter is made available. It will be seen that horizontal circulation may be established at a substantial distance laterally from the casing 55 by this method of operation.
Figure 9 shows what may be termed a mole which serves to carry solvent inlet tube 10 horizontally in dissolving pool H. The so-called mole 12 may be run either by electricity or by being I! and electricity being carried to the mole by cable 16. In this modification of the invention, brine is pumped into pipe 10 by suitable pumping means, passes through mole 12 and thence through the cutter and" across the .face of mineral bed TI. Thence, it I'circulates upwardly through casing 14 from where it is exhausted to suitable precipitating means.
It will be observed that a number of mechanical apparatus have been disclosed to accomplish the feature upon which the main object of this invention depends, that is, the development of a horizontal circulation component in a pool of dissolving liquor acting upon the mineral being mined. 7 However, it is not intended that the invention shall be limited to the specific showing of mechanical apparatus disclosed.
The operation of mining potash salts has been specifically referred to in this specification but the principle is important in other arts. For example, efforts have been made to dissolve limestone from oil formations in a substantially horizontal direction so thata larger producing area may be worked from a single hole wherein hydrochloric acid is used as a solvent for the limestone. The 'difficulties herein presented are that the flexible tubing used will not provide a sufficient compression strength to withstand strong jetting by the holes, this being necessary .in dissolving limestone with hydrochloric acid.
It will be obvious that the modifications in Figures 2, and 9 overcome this diinculty.
It is also known that drilling can be accomplished horizontally for distances to 1500 to 2000 feet. This method may be adapted to the production of salts from thin potash beds to great advantage and may be accomplished in two ways, the first of which'is shown in Figure 10. A large shaft 18 is put down to the salt bed. At the bottom of the shaft is built a chamber 19 which may be from to 20 feet in diameter. This chamber is made water-tight and strong enough to withstand the hydrostatic head at the depth being worked. Holes are then drilled into mineral bed 80 in a horizontal direction in a way known per se. For purposes of simplicity, only one horizontal drill hole is shown but any number may be used. When the hole has been drilled, pipe 8| is set so that its further extremity is put approximately at the end of the horizontal hole and unsaturated solvent is pumped into the bed by suitable means. This solvent circulates backwardly along the pipe 8| and rises to the surface in the annular space between pipe 8| and production pipe 82 from which it is delivered to suitable precipitating means. It will be seen that by this method very thin beds of salts can be economically worked. Sometimes it is desirable to have solvent pipes 81 enter the bed and allow shaft 18 to be the production opening. It is sometimes desirable to drill into the further extremity of pool 83 and to produce salt.
by circulation through such drill hole, thus maintaining horizontal circulation through the bed, circulation entering pipe 82 of Figure 10.
The second means of establishing circulation, as previously indicated, is shown in Figure 11. As an example of this operation, where the salt bed lies at a depth of 1000 feet by oil well drilling methods known per se, a drill hole is turned to an angle of 45 with the vertical at approximately 700 feet. A smaller drill hole is then continued from the bottom of the first hole and by the methods used for horizontal drilling, the hole is turned horizontally and so drilled into the salt bed for the desired distance. Brine is pumped through pipe 84 downwardly and horizontally into the salt bed and travels thence back along pipe 84 horizontally in the bed and upwardly in pipe 85 and thence to suitableprecipitating means.
It is often of advantage to heat the saturated solvent liquor to get better action, especially in potash ores. The fact that most potash salts take up heat on solution in water indicates that the addition of heat greatly aids in quick solution 01' the salt.
Having thus described the invention, what I claim as new and desire to secure by Letters Patent of the United States is: a
1. A method of mining potash from relatively thin beds of potash salts which comprises forming a pool of a solvent liquid in the potash bed, directing said liquid against a lower portion of said bed and causing the liquid to move upwardly against the face of said bed.
2. A mining apparatus of the character described comprising, in combination, means for forcibly circulating a solvent liquid to a pool of liquid in a subterranean deposit, means for laterally extending said forcibly circulated liquid a substantial distance along said deposit to form a channel, means for delivering said circulating liquid forcibly against a face of said deposit adjacent the far end thereof, thereby causing a circulation in a reverse direction substantially horizontally along said deposit, and means for removing the circulating liquid from said deposit.
3. A mining apparatus of the character described comprising means for continuously circulating a solvent liquid to a pool of liquid in a subterranean deposit, means for continuously" and positively directing the liquid against the deposit in the direction in which the deposit is to be mined and in a lower portion of the pool in such'a way as to cause the liquid to flow upwardly across the face of the deposit, and means for continuously removing the upwardly flowing liquid from the pool.
4. An apparatus as claimed in claim 3 in which the means for continuously and positively directing the liquid against the deposit comprises a cutter.
5. A system for mining potash from relatively thin underground beds of potash salts comprising the combination of, a single drill hole from the surface of the ground to said underground bed, a laterally extending drill hole in said potash bed connecting at one end with said single surface drill hole, means for introducing a solvent liquid for potash unsaturated with respect to the potash salts in said bed laterally into said laterally extending drill hole at a point near the extremity thereof substantially removed from said surface drill hole and against the face of said potash bed in a lateral direction in which the potash is to be mined wherelryv said solvent liquid dissolves the potash from the face of the bed and creates a horizontal component of circulation in a reverse direction along the potash bed toward said surface drill hole thereby causing the solvent to become more saturated as it travels back along the bed, and means for removing the circulating liquid through said surface hole at a point where it is substantially saturated with respect to potash.
6. A method of mining potash from relatively thin underground beds of potash salts which comprises, drilling a hole into the potash bed from the surface of the ground, drilling laterally from channel, introducing a solvent liquid unsaturated with respect to potash through said suriace .drill hole and said channel and forcibly bringing it into contact with the face of the potash bed at the far end oi said channel thereby causing a horizontal component of circulation backwardalong said channel in the direction oi. said surface hole and continuously removing substantially saturated portionsoi said liquid through said surface drill hole.
I 7,. A method of mining potash from relatively thin underground beds of potash salts'which comsitid surface hole into said underground bed a 1 substantial distance to form a laterally extendingprises an entry hole into the potash bed from the or the ground, forming a laterally extending channel from an opening into the bed, introducing a solvent liquid unsaturated with introduced through the entry hole.