Untitled record

(No model.j

H. FRASCH.

MINING GOLD OR LIKE METAL.

Patented Aug. 4, 1896.

lo. 565,342.

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United States Patent Office.

HERMAN FRASCH, OF CLEVELAND, OHIO.

MINING GOLD OR LIKE METAL.

SPECIFICATION forming part of Letters Patent No. 565,342, dated August 4, 1896.

_c Application filed August 17,1895. Serial No. 559,672. (No model.)

To all whom it may concern:

Be it known that I, Herman Frasch, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of 5 Ohio: have invented certain new and useful Improvements in Mining Gold or Like Metal; and I do declare the following to be a full, clear, and exact description of the invention.

This invention relates more particularly to io the recovery of gold from placer deposits which either contain the gold in too small quantity for working by the methods heretofore known or used, or which from lack of water or peculiarity of location are not work15 able, at least profitably, by said prior methods. It may, however, be applied to the recovery of gold from other porous or permeable deposits and to the recovery from such deposits of analogous metal, (silver or 2o platinum, for example,) and it is generally to be understood that each of the improvements constituting the said invention is intended to be secured for all the uses to which it may be applicable.

In accordance with said invention a reagent, which converts the naturally insoluble gold or analogous metal into a compound or compounds soluble in water, is introduced into the porous or permeable auriferous or 30 analogously metalliferous earth, which is generally sand or gravel, as it lies in its natural bed in the ground. The aqueous solution of gold or the like, formed by the aid of such reagent, is removed by any known or suitable 35 means for conveying liquids, such as pumping or the like, including drainage, if the situation admit of it, and the gold or like metal is recovered from the solution by known or suitable means for recovering metal from so40 lution, such as chemical precipitation, electrical deposition, or the like. Where the earth contains other like metal as well as gold, these m,ay be mined together by using a reagent which converts both into soluble com45 pounds, or they can be mined separately by using in succession reagents of which each renders one of the metals soluble.

In the introduction of thfe reagent which renders the gold or like metal soluble hy50 drostatic columns, pumps, or other pressure applying means may be used to force the reagent intotheearth, or reliance may be had, when theearth is sufficientlypermeable, upon gravity alone. Practically the use of pressure is important and is specially claimed. 55

The reagent employed may be any known or suitable substance or combination of substances for forming soluble compounds with gold or like metal, such as chlorin and bromine for gold, the alkaline hyposulfites for 60 silver, and potassium cyanid for gold or silver, or both. Chlorin maybe advantageously used for platinum. Thisis often present with gold and can be mined with it by means of chlorin. These are given as illustrations. 65 Other reagents maybe used. In using a combination of substances they may be used in admixture or in succession? An example of the successive use of substances would be the formation of silver chlorid by the intrbduc- 70 tion of chlorin and the making of this silver chlorid soluble in water by means of sodium hyposulfite.

It is most advantageous to use the reagent in aqueous solution, such solution being in- 75 trodueed into the auriferous or argentiferous or platiniferous earth in its natural bed in the ground and allowed to remain for a suitable time in contact therewith in percolating or while standing. The more or less strong 80 solution of gold (or silver or platinum, or two or more of them) is then withdrawn.

The gold and like metals are, as a general thing, distributed unequally through placerdeposits, the working of which is more par- 85 ticularly the object of the present invention. The gold, for example, in such deposits is, as a rule, mainly or almost Whollj· in the lower part near the bed-rock. The reagent may be allowed to find its way to the metal through 90 overlying or inter-mediate masses of earth, which are but slightly or- not at all auriferous or argentiferous or platiniferous; but it is an improvement to drive a well, shaft, ditch, or tunnel to or near the auriferous or 95 argentiferous or platiniferous portion of the mass and to introduce the reagent more directly thereto by means of such well, shaft, ditch, or tunnel. Practically wells or shafts would be sunk or driven (at least in most 100

565,342 cases) down to the bed of the rock, so that the pit of the well or shaft is in the metalliferous earth.

Sometimes it may be desired to mine the 5 metal from auriferous or like earth, which is so flooded with water as to interfere with the penetration or operation of the reagent. In such cases it may be possible to drain off the excess of water; but if this is not practiio cable, orit be preferred not to do so, achemical solution of a suitably high specific gravity may be introduced under the water-carrying earth and be made to displace the water, so that the reagent may enter and act upon 15 the gold or like metal. A proper specific gravity of the chemical solution may be obtained (at least in some cases) by the use of a sufficient quantity of reagent; but where this is too expensive or for any reason is not 20 desirable it may be secured by additions of other substances, the most convenient substance being common salt, (sodium chlorid.)

As already indicated, the reagent may act upon the gold or like metal in percolating 25 through the ground or while standing therein. To collect the metallic solution formed in percolation, intercepting receptacles are provided at a suitable depth having openings or outlets for giving access -thereto. These re30 ceptacles may be simply the pits at the bottom of wells sunk into the mine, or they may be formed by open or covered ditches, or they may be formed in whole or in part by artificial walls, (vertical or horizontal,) or they 35 may be formed in other like ways. To provide for the reagent standing in contact with the gold or like metal, walls may be built in the mine, so as by themselves or in connection with the natural rock to form cham40 bers or basins inclosing the auriferous or argentiferous or platiniferous earth, access for removal of the solution of gold or like metal being given by shafts or other openings. These could serve also to introduce the chem45 ical solution, which might,however,be allowed to percolate into the basin. In some cases artificial basin-forming walls may not be necessary, the reagent when introduced into the ground standing sufficiently in consequence 50 of the nature or natural surroundings of the auriferous or like earth. In such case (as also in the case of an artificially-formed basin) the same pipe, well, shaft, or tunnel may serve to introduce the reagent which renders 55 soluble the gold or like metal and to remove the solution of gold or like metal. The reagent can be applied to the same earth and the metallic solution removed therefrom repeatedly, as often, in fact, as a yield is ob60 tained.

The mine to be treated in accordance with this invention is generally a deposit in an excavation in solid rock, (such as the bed of an ancient river,) and the most advantageous 65 treatment (itself a special improvement) is to build one or more walls at intervals across the excavation or valley (they extending from the bed-rock upward to the surface or to any desired distance above or below the same) and to sink or drive a number of wells or 70 shafts at intervals in the parcels of ground above such walls.

; As already stated, it is an advantage and a special improvement to force the reagent into the earth. It is also an advantage to exhaust 75 the solution of gold or like metal from the earth by the aid of a vacuum or diminution of pressure in the earth around the well-pit below the level of such solution.

In order to enable those skilled in the art 80 better to understand and carry out the invention, the following particular examples are given by way of illustration of certain modes of practicing the invention, reference being had to the accompanying drawings, which 85 form part of this specification, and in which—

Figures 1 and 2 are diagrams, respectively in plan and longitudinal section, of a mine in an ancient river-bed provided with artificial basin-forming walls and with wells or shafts 90 whose pits constitute intercepting receptacles. Fig. 3 is a diagram of the same mine in cross-section on line i i i of Fig. 1. Fig. 4 is a diagram in vertical section of a hillside mine; andFigs.5,6,and7arediagramsof wells 95 provided with pumping machinery which may be used for introducing or forcing the reagent into the minc or for removing or exhausting and removing the solution of gold or like metal or for both purposes. Fig. 8 is a dia- 10c gram showing the lower end of a reagent-introducing or reagent-removing pipe on a larger scale than that of the other figures and in section.

Let it be assumed that the mine consists of 105 auriferous sand and gravel A and overlying earth A', which contains little or no gold, deposited in the bed of an ancient river between the banks B, and that such deposit averages twenty feet in depth and two hundred feet in no width, the dip of the bed-rock 0 being fifty feet to the mile. These figures substantially represent an actual case. The diagrams, it will be understood, are not intended to preserve the proportion to one another of the dif- 115 ferent dimensions. It will, of course, also be understood that the dimensions and other circumstances and their relations to one another are variable in reality. At intervals of about half a mile or at greater or less inter- 120 vals trenches may be dug across the valley down to the bed-rock. These trenches are filled with cement concrete, forming solid impervious walls D with about half a mile (or more or less, as the case may be) of deposit 125 between adjacent walls. These parcels of ground would, of course, be the width of the valley across. In them, at, say, about one hundred feet or at greater or less distances apart, wells E may be driven down to the bed- 130 rock and provided with suitable pipes Greasings or pipes and casings.

565,342

In Fig. 5 the well is shown provided with a pipe 2, which fits closely the bore of the well, so that a vacuum can be maintained in the well-pit, the surrounding earth forming a 5 packing. The pipe is shown as resting on the bed-rock and is provided with perforations near its lower end. Preferably the pipe 2 is of iron, coated internally and externally with lead, although it may be of wood or lead, or io any material of suitable strength able to resist or protected against corrosion by the reagent. Near its upper end the pipe 2 is com nected through anon-corrodible pump 3 with a lead-lined or other non-corrodible tank 4, 15 which latter is provided with a non-corrodible pipe-line 5. The pump 3 removes the metallic solution from the well and delivers it into the tank 4, to be thence discharged by the pipe 5. The tank 4 might also serve to 20 receive the chemical reagent and the pump 3 to withdraw it therefrom through a suitable connection with the bottom of the tank and force it through the pipe 2 into the metalliferous earth, A or the reagent may be introduced 25 from any suitable source through the pipe 2 independent of the pump, or part may be run in directly through the pipe 2 and part be forced down by the pump 3.

In Fig. 6 the well is provided, like an oil30 well, with a casing 2' to inclose the pipe 2, and an underground pump (not represented) whose sucker-rod 6 is shown connected with one end of a walking-beam 7, the opposite end being provided with a chain or rope 8, that 35 leads to an engine (not shown) for reciprocating it and the sucker-rod. The easing is perforated near the bottom. The pump raises the metallic solution and delivers it through the pipe 2 into the tank 4, from which it may 40 be discharged by the pipe 5. For introducing the reagent the pump with its pipe and packer could be removed and a pipe and packer inserted for introducing the reagent.

In Fig. 7 the tank 4 has its bottom and top 45 both connected with the pipe 2, and a branched pipe 9, with a valve in each branch, leads to both the induction and discharge sides of an air-pump 10, so that air can be forced into the tank 4 or be exhausted therefrom, as 50 the operator may determine. A stopper 11 for closing the bottom opening when desired is indicated in dotted lines. By filling the tank 4 (through the pipe 5 or otherwise) and then compressing air into it by the pump 10 the 55 reagent may be. forced down the pipe 2, the stopper 11 being raised and the pipe 5 closed and the pipe 9 being in communication with the compression side of the pump 10. By shutting the stopper 11 and putting the pipe 60 9 in communication with induction side of the air-pump a vacuum can be made in the tank 4 and the metallic solution made to rise through the pipe 2 and flow into the tank 4. By opening the pipe 5 (the stopper 11 being shut) and 65 causing the pump 10 to force air into tank 4 its contents may be discharged through the pipe 5.

The wells of Figs. 1, 2, and 3 may each be equipped like the wells of Figs. 5, 6, or 7, or in any other suitable way. The arrange- 70 ments of Figs. 5 and 7 are intended for shallow wells, as they raise the solution of gold or like metal by vacuum; but the arrangement of Fig. 6 could be used with wells of any depth. A force-pump could also be used at 75 the bottom of shallow wells. Other forms of pumping or lifting apparatus could be used instead of piston-pumps. When the wells are only twenty feet deep, they may be easily dug by hand. With drive-pipes or hydraulic 80 wash-pipes almost any depth can be reached.

Assuming that gold is to be recovered, the reagent may be chlorin. This can be conveniently prepared in solution by dissolving chlorid of lime (bleaching-powder) in water 85 and adding enough sulfuric acid to liberate the chlorin. The use of about four pounds of the chlorid of lime to a ton of water is recommended. The solution can be used at once, or be first allowed to settle. It is in- 90 troduced into the auriferous earth through one or. more of the wells, and may be introduced in sufficient quantity to soak the auriferous earth in the entire basin formed by a wall D. To do this, the height of the Avail D 95 (on the basis of a dip of fifty feet to the mile and half a mile between walls) would have to be twenty-five feet plus the depth of the auriferous deposit at the upper end of the basin. If the walls were only a quarter of a mile 100 apart, their height might be twelve and onehalf feet less with the same dip. It is not necessary, however, to fill the whole basin. The solution may be introduced at one or^?more of the wells and be allowed or forced to 105 percolate to others, from which it could be pumped out. A continuous flow might, in fact, thus be maintained. If the overlying earth A'is sufficiently impervious, the solution might be made ⁺o flow out of a well by pres- no sure of the solution in the stratum A, The solution might simply be forced into the sand or gravel about a well, left there for a suitable time, and then pumped out through the same shaft and even the same pipe, the oper- 115 ation being repeated as often as desired until the yield ceases.

It is generally recommended to introduce the solution at the highest well and remove it at the lowest, or at one of the intermediate 120 ones if it be sufficiently charged with gold.

The solution may remain in contact with the gold-carrying deposits for hours, days, weeks, months, or even years. Weak solutions may therefore be used, and the extrac- 125 tion can be continued until practical exhaustion of the gold. Any depth can be worked. As placer deposits do not ordinarily contain sulfids, nor other substances on which the chlorin would waste itself, loss from this 130 cause would usually not have to be taken into account. In some cases where organic matter exists a solution of cyanid of potassium can be used more advantageously. It

565,343 can be handled with iron pumps and iron tanks. Solutions of two - tenths of one per cent, (or even one-tenth) will answer. In using chlorin for gold, if there be silver in 5 the deposit, the chlorid of silver formed thereby could be recovered by means of hyposulfite solution. If there be platinum, it would be recovered with the gold by the chlorin.

When a sufficiently-rapid percolation is i o obtained thereby, the solution may simply be run into the wells; but when desired it can be forced by pressure in the wells to penetrate the surrounding earth.

The hillside mine in Fig. 4 is provided at 15 an elevated point with a reagent-introducing opening F in the auriferous or like earth A and overlying deposit A' in the form of a ditch and at a lower point with a cement wall D from the bed-rock C to and above the top 20 of the ground at that point. In the ground above, the wall D and in proximity thereto is a well E and below it a ditch G, which extends to bed-rock C. On introducing the reagent in aqueous solution into the ditch F by pumps, 25 buckets, conduits or other like means, said solution flows down the hillside, percolating through the auriferous or like earth A, converting the gold or like metal therein into a compound soluble in water and dissolving the 30 same. The wall D intercepts the metallic solution so formed, which can be removed through the well E by the appliances of Figs. 5, 6, and 7, or by other like means. In some cases gravity might force it to rise through 35 the well-pipe; also, it might be drained off through an Opening at or near the bottom of the wall D into the ditch G, from which it might be lifted out by pumps or buckets or other liquid-lifting appliances; also, the solu40 tion might be carried (if the situation permit) into a storage or treating vat at a lower level by drainage directly from the receptacle or basin above the Wall D or from the ditch G. If desired, the solution can be removed as 45 fast as it percolates into the receptacle formed by the wall D, or it can be allowed to collect therein and to stand in contact with the gold or like metal before it is removed. Further, the wall D and well E might be dispensed 50 with, and the solution be intercepted by the ditch G, to be removed by pumping, drainage) or otherwise. Of course also the wall D might be used without the ditch and without ' the well E, if other suitable outlet be pro55 vided.

After the gold solution has been obtained, the gold is recovered therefrom as may be preferred. Electrical deposition is considered the most advantageous mode, the chlorin 60 solution being regenerated while the gold is deposited. If is unnecessary to go into the details of an electric deposition, as those skilled in such matters will understand how to apply it. So, also, if chemical precipitation be 65 preferred for the recovery those skilled in the. art will understand how to apply it without further instructions. The regenerated solulution of chlorin could be introduced again into the auriferous earth.

If an analogous metal, like silver or plati- 70 num, is to be mined instead of or along with gold, the preceding description will suffice for skilled persons to accomplish the formation in the ground of a solution of such metal as well as the removal thereof from the ground 75 and the recovery of the metal from the solution, electrical deposition and chemical precipitation being available, as when gold is mined alone.