US2164364A - Placer gold concentrator and amalgamator - Google Patents

Description

y 1939. E. A. WILLNER. SR 2,164,364

PLACER GOLD CONCENTRATOR AND AMALGAMATOR Filed March 21, 1936 2 Sheets-Sheet 1 arwwvkw E. A. T'Vl'ilner, S1:

July 4, 1939. wlLLNER 5 2,164,364

PLACER GOLD CONCENTRATOR AND AMALGAMATOR I Filed March 21, 1936 2 Sheets-Sheet 2 E. A. I Villner, Sr:

Patented July 4, 193

UNITED STATES PATENT OFFICE PLACER GOLD CONCENTRATOR AND AMALGAMATOR 1 Claim.

The present invention is in the nature of an improvement on the placer gold concentrator shown and described in the patent to Cave, No. 1,387,238, patented August 9, 1921. In general,

the present invention has for its object all of the objects enumerated in the Cave patent with some additional objects mentioned hereinafter.

The main object is the provision of a device for concentrating and refining placer gold ores more economically and more efiiciently and more thoroughly than is possible by means of the concentrator shown and described in the aforementioned patent.

Another object is the provision of a device and of a method especially applicable for refining placer gold ores in which the gold occurs in the form of extremely minute particles known as flour gold.

Another object of the invention is the provision of a device for rejecting all the coarser particles of ore and for treating the fine ore particles containing the flour gold in order to separate the flour gold from the tailings.

Another object of the invention is the provision of a device for separating the minute ore particles from the coarser material and then treating the finer particles With mercury for separating the flour gold from the mass of fine particles of ore.

Another of my objects is the provision of a speciallized form of centrifugal bowl for breaking up the surface tension of the film surrounding the particles of fiour gold so that the gold may come into amalgamating contact with the mercury in the bowl.

Having in view these objects and others which will be pointed out in the following description, I-

will now refer to the drawings, in which Figure 1 is a view in side elevation and largely 10 in diagrammatic form, showing the device as a whole.

Figure 1A is a view of a fragment of the device shown in Figure 1 and showing particularly the means for the adjustment for the lower end portion of the rolling screen.

Figure 2 is a view in end elevation and also largely diagrammatic, showing the device as a whole.

Figure 2A is a view of a fragment of the device 50 shown in Figure 2, the View showing a slight modification from that of Figure 2.

The grizzly or trommel screen, which initially receives the ore, includes a foraminous s1owly-. rolling drum I0. This drum is provided with a 55 pair of tires ll each resting on a pair of rollers rests on the transverse angle beam I 8 and it is 1'0,

prevented from sliding downwardly by means of ears l9 depending from the beams 20. At the rear end of the drum I0 is a vertical support 2| the form of which is best shown in Figure 1A.

This is formed of angle iron as is also the beam 15" 20 which may be secured to the beam 2| by means of bolts passing through the apertures 22 of the beam 2|. In this manner the rear end portion of the drum I 0 may be raised or lowered for altering the rate at which the ore passes through 20 the drum [0. A stationary water pipe 23 passes through the drum ID to spray fine streams of water against the ore passing through the drum. The water pipe 23 is connected to a water line 24 which in turn is connected to a suitable source 25 of water under pressure.

The larger particles of ore pass out through the lower open end of the drum l0 but the finer particles fall through the openings in the drum and into the launder 25. This launder is sta- 0 tionary and it is downwardly and forwardly inclined. The small particles of ore are carried by the constant stream of water toward the inclined floor of the launder 25 and into a downwardly and forwardly inclined chute 26. The 35 chute 26 has a telescopic end portion for delivering the ore to the hopper 21. This latter hopper is best shown in Figure 2. Inside the hopper 21 is an involute scoop 28. This scoop picks up the material in the hopper 2i and carries it toward its center of movement. Referring back to Figure 1, it will be noted that the axis of the scoop 28 is the hollow shaft 29. This tubular shaft 29 has an opening 30 for receiving the ore from the scoop,

28. The ore is then pushed through the hollow shaft 29 in the direction toward the left as viewed in Figure 1. The passage through the hollow shaft is, however, blocked by a partition 3| which prevents the further movement of the ore. Im-

mediately to the right of the partition 3|, as

Figure Zand it consists of a screen material or rather fine mesh. A helical conveyor 34 is secured to the hollow shaft 29 to rotate therewith to carry the ore in the concentrator 33 in a direction toward the left, as viewed in Figure 1. The conveyor 34 consists of a helical fin which is spaced from the shaft 29 so as to convey the wet ore without conveying the entire mass of water. The water level is kept at or near the lower edge of the hollow shaft 29 so that the slushy ore is not only kept moving toward the discharge end of the concentrator 33 but it is also kept agitated so that the finer particles of gold will not tend to settle down in the mass which is later rejected but will be caused to approach the screen. The mass of ore is thus moved toward the left, as viewed in Figure 1, until it encounters the opening 35 which is the outlet to a second involute scoop to admit the ore into the shaft 29 from whence it is discharged as rejected material. The shaft 29 is provided with a partition 36 for preventing reverse movement of the ore in the hollow shaft 29.

In the concentrator 33 the ore is moved lengthwise under constant agitation from the helical conveyor 34. The constant agitation results in the passing of the fine gold along with the finer particles of sand through the walls of the concentrator 33. The coarser particles of ore minus the fiour gold are discharged through the hollow shaft 29. The flour gold together with the fine particles of sand and soil are dropped into the hopper 31. The hopper 31 is a stationary hopper with solid walls for retaining the water and concentrated gold ore and for delivering it to the outlet 38. Inside the hopper 31 there is a screw conveyor 39 which is actuated by the driven shaft 40. The movement is toward the right, as viewed in Figure 1, so that the concentrated and finely divided ore is carried out through the opening 38.

The finely divided, concentrated ore is carried out through the conduit 38 and forward into the amalgamator 4|, as shown in Figure 2. Eventually the lighter portions of amalgam will be skimmed off from the grooves of the amalgamator and it will pass out through the chute 46 together with the sand and water. The gold amalgam thus skimmed 01f would be lost unless provision were made for its recovery. Referring to Figure 1, 5| designates one or more receptacles designed for recovering the gold amalgam. The first one of these receptacles is positioned where it will receive the discharge from the chute 46 and it is provided with an outlet spout positioned. at a slightly lower level than the chute 46. When two or more receptacles 5| are employed, the second receptacle is so positioned that it will receive the discharge from the first of the receptacles. Any number of receptacles 5| may be employed but each receptacle is positioned at a lower level than that of a preceding receptacle. Each receptacle is provided with a vertical baiile 52 dividing the receptacle into two parts of greatly unequal volume. These baffles 52 terminate above the bottoms of the receptacles so as to permit the free flow therethrough of the material discharged from the spout 46. The material first enters the smaller compartment in which the baffle 52 breaks up the violent eddy currents before the material reaches the bottom edge of the baffle. The upward fiow through the larger compartment of the receptacle 5| would be in the form of a quiet, slow-moving current were it. not for the baflle 53,. This baffle 53 imparts a slightly spiral movement to the flowing mass, the movement being aboutv a horizontal axis to direct the heavier material toward.

the bottom of the receptacle 5|. The movement of the mass is, however, rather quiet without any violent agitation which would disturb the gold amalgam which settles to the bottom of the receptacle. The second receptacle 5| will accumulate only that portion of the gold amalgam which passes out through the first receptacle 5|. The number of receptacles 5| must be determined on the job and it depends largely on a number of factors which are peculiar to each field.

The material discharged from the last of the receptacles 5| may or may not contain slight traces of gold or of gold amalgam. Final recovery of such traces of gold or gold amalgam may be made by means of the vibrating chute 54. This chute is provided with means for causing its vibration in a direction transverse to the direction of the flow of the material over the floor of the chute. The floor of the chute 54 consists of transverse slats 55 in imbricated relation. Each slat is covered with a sheet 56 of cop-per having a coating of silver amalgam. This will tra any remaining particles of gold or of gold amalgam leaving the last of the receptacles 5|.

The entire structure is a unit and its operation is thus very simple. The water line 24 feeds all the necessary parts of the device, valves being introduced into the water line and its connections wherever they are necessary so that the water for the entire system or for any part thereof may be shut off. The driving mechanism is so arranged that all parts of the device are driven from the drive shaft 51 which may be connected to any suitable source of power. This shaft is provided with a pulley 58 for imparting movement to the pulley 59 on the shaft IS. The drive shaft 51. also carries another pulley 69 for imparting movement to the pulley 6| on the shaft 29. A third pulley 62 on the drive shaft 5'! is connected with the pulley 63 on the shaft 42 for driving the amalgamator. An arm 64 has an eccentric connection with the pulley 60 and this arm is pivotally connected at 65 to the vibrator 54 for imparting transverse vibratory movement thereto.

It is to be understood, however, that these pulleys may all be replaced by sprocket wheels or any other mechanical equivalents for imparting the necessary movements from a drive shaft to the other parts. Numerous modifications are also possible in other parts of the device. One of these is shown in Figure 2A in which the telescopic chute 38 may be replaced by a forked chute 3811.. In some fields the concentrates are fed from the machine more rapidly than a single amalgamator can handle them. In such cases it is desirable to provide two independent amalgamators which may be operated simultaneously. At other times it is desirable to keep the machine running while one amalgamator is being drained of its gold amalgam. In all such cases the arrangement shown in Figure 2A will be found to be highly desirable. In this case the chute 38a has two branches 38b for conducting the concentrates to two separate amalgamators. The device is also provided with a valve 380 for closing either one or the other of the branch chutes 38b or for leaving both chutes 381) open.

Flour gold occurs in many parts of the world but usually in streams. The form of the gold is very pure and it occurs in such immense quantitles that it has for many years bafiled metallurgists and others who have tried to devise methods for its recovery. Although occurring in such quantities, the flour gold is found in sand in all degrees. of fineness which must be separated from the gold and discarded. This in itself is a difficult problem but the problem is made much more difiicult by the character of the flour gold itself. The particles are so extremely fine that they tend to remain suspended in flowing water which would carry the sand. Because of the large surface of the particles as compared with their volume and weight, the surface tension has resulted in a problem which has heretofore been insoluble.

The present invention is characterized by the fact that no powerful currents of water are employed for separating the flour gold from the sand and gravel. In my concentrator the material is conveyed through a relatively quiescent mass of water. This permits the gradual but steady movement of the mass of material with just sufiicient agitation to keep the entire mass of material suspended in the water while it is being moved. The screen is thus enabled to discard all the coarser sand and the gravel with the minimum of flour gold adhering thereto.

All of the machinery is coordinated and automatic. A single drive shaft drives all of the other shafts employed in the machine and a single water line supplies all of the water to the various parts of the device. The sand and gravel with the fiour gold is fed into the machine and at the end of the run the gold is taken out in the form of gold amalgam. This amalgam may then be put into a retort for the recovery of both the gold and the mercury. The entire operation takes place on the claim where the ore is found and it thus eliminates almost entirely the transportation problem which might otherwise be, quite expensive. In many cases it is possible to transport the ore from the ore bed to the machine under the action of the current of the stream so that the ore need merely be excavated from its bed. Almost the only thing involving a transportation problem is the gold itself which is shipped in bullion form direct to the mint.

Having thus described my invention in such full, clear, and exact terms that its construction and operation will be readily understood by others skilled in the art to which it pertains, what I claim as new and desire to secure by Letters Patent of the United States is:

A placer gold concentrator comprising a drum having peripheral perforations and open ends,

means for rotatably mounting said drum with its axis inclined, means for supplying ore to the higher end of the drum, means for spraying water against the ore in the drum whereby the ore and water travel down the inclined inner surface of the drum and the finer particles and water pass through the perforations while the larger particles pass out of the open lower end of the drum, a launder below said drum to collect the finer particles of ore and water passing through the perforations, a hopper, a conduit for carrying finer particles and water from the launder to the hopper, a hollow shaft rotatably mounted extending over said hopper, said shaft having an opening therein adjacent the hopper and leading interiorly, a scoop mounted on the shaft adjacent the opening to dip into the hopper to transfer ore and Water to the interior of the shaft, a cylindrical screen mounted around the shaft, a partition in the shaft located inside the screen, said shaft having an opening inside the screen adjacent the partition at the side nearer the said hopper allowing ore and water to pass out into the screen, a helical conveyor ribbon attached to said shaft and spaced therefrom except at the points of attachment, the outer edge of said ribbon lying close to the bottom of said cylindrical screen, said hollow shaft having a second opening therethrough located in the screen at a position remote from the first said opening and at the opposite side of said partition, a scoop on the shaft adjacent the said second opening to transfer ore and water from the screen thereinto, and a hopper beneath said screen to receive fine particles and. water passing therethrough, said drum removing coarse ore particles and permitting onlythe finer particles to reach said launder, said conveyor ribbon agitating the finer particles and water and advancing them along the screen whereby flour gold settles through the screen with the water and the lighter ore particles and entrained water are lifted into the hollow shaft and pass therethrough, said screen and conveyor ribbon being operated with a liquid level near the lower edge of the shaft whereby the ribbon operates below the liquid surface to agitate and advance the ore settling on the screen without advancing the mass of water overlying the ore.

ERNEST ALFRED WILLNER, SR.

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