US794552A - Art of treating ore and gathering gold or precious metal diffused in the employed mercury. - Google Patents

Description

NO. 794,552. PATENTED JULY 11, 1905. G. M. EIOE. ART OF TREATING OEE AND GATHERING GOLD OE PRECIOUS METAL DIFFUSED IN THE EMPLOYED MERCURY.

APPLICATION FILED MAE. 21.1903.

UNITED STATES Patented July 11, 1905.

PATENT @rrica.

GEORGE M. RICE, OF WORCESTER, MASSACHUSETTS.

ART OF TREATING ORE AND GATHERING GOLD 0R PRECIOUS METAL DIFFUSED IN THE EMPLOYED MERCURY.

SPECIFICATION forming part of Letters Patent No. 794,552, dated July 11, 1905. Application filed March 21, 1903. Serial No. 148,822.

To ail whom it may concern:

Be it known that I, GEORGE M. RICE, a citizen of the United States, residing at Worcester, in the county of Worcester and State of Massachusetts, have invented a new and useful Improvement in the Art of Treating Ore and Gathering Gold or Precious Metal Diffused in the Employed Mercury, of which the following is a specification.

In Working what is known in the art as barrel processes and pan processes for treating ores containing gold or precious metal the quantity of mercury practically employed for effecting the amalgamation thereof exceeds by many times the Weight or quantity of the gold or precious metal contained in the ores treated, and if the ore contains gold as the major part of the value of the metals sought to be recovered by such amalgamation it has been found in practice that a part of the gold present in the mercury cannot be recovered as amalgam or yielded up by the squeezing operation by which the amalgam is separated from the larger quantity of mercury, since the flowing out of the mercury when squeezed carries with it a material percentage of gold. The same actions occur under the stated conditions with silver as with gold. Heretofore such mercury-containing gold has been treated by f retorting to re' cover the contained gold or metals, a tedious and costly process when a large quantity has to be worked, and by reason of its expensiveness prohibiting the working of certain gold ores by processes requiring large quantities of mercury.

The object of my present invention is to afford a practicable, efficient, and less expensive process for treating ores and for the economic recovery of gold or gold with silver as an allied metal when difl'used with a comparatively large quantity of mercury in the amalgamating operations.

A feature of my invention consists in adding to the mercury during or subsequent to the ore-amalgamating action a quantity of finely divided, comminuted, or precipitate particles of metal of an amalgamative nature for the purpose hereinafter explained; also,

in the improved process of treating ores and mercury for amalgamating and gathering gold or precious metals, as hereinafter specified and definitely set forth in the summary.

In the accompanying drawings I have illustrated in Figure 1 a front view, partly in section, of an apparatus that may be employed in working my improved process, and in Fig. 2 a vertical section of one form of container suitable for use in loading the employed mercury with a scavenger medium subsequent to the diffusion of gold within said mercury.

As a brief description of the parts, A denotes a rotatable carrier mounted on an arbor or shaft; F, the supporting-frame; B, the tumbler or cylinder for containing the charge for treatment; C, clamping means for removably securing the container-cylinder to the carrier, and D the drive-belt or means for imparting rotative movement to the carrier.

E indicates the removable cover of the container, and c' means for tightly securing the cover in closed position.

0 indicates the charge of ore and water, and P the pebbles or percussion devices within the container.

In Fig. 2 the container 6 is shown provided with trunnions t, mounted in hearings on frame F and provided with a wheel a and a crank S for rotating or tumbling the container for distributing added metallic particles through a mass of mercury m, having gold diffused therein for the efficient recovery 'of the gold in accordance with my invention.

. The improved process claimed is not dependent on the particular mechanism shown, but can in practice be worked with the aid of any suitable apparatus.

An apparatus of similar character to that shown in Fig. 1 has been made the subjectmatter of a separate application for Letters Patent for a mechanism; but the present disclosure has reference to the improvements in the process irrespective of apparatus for its working.

In carrying out my present process the ore, if hard, is broken, as heretofore, in a breaker, or if the ore is soft and easily crushed it may be used in its natural condition. Such oreis charged into a vessel or container, preferably of cylindrical form, of a length somewhat greater than its diameter and capable of being tightly closed or sealed up, together with a quantity of hard rock pebbles, such as are found in all mining regions. A suificient quantity of water is also added, so that the ore, Water, and pebbles will play or mingle together when the cylinder is tumbled over and over endwise by suitable mechanism and the contained mass projected or thrown violently from end to end of the cylinder. This action is continued from half an hour to two and a half hours, more or less. or until the ore is very finely ground or pulverized by the percussive action of the loose pebbles and the contained metal thereby scoured and prepared for amalgamation. The time required for this effect varies somewhat accordingly as hard or soft ore is being treated. When this preparatory action has progressed for a sufficient time, the container is opened and a suitable quantity of mercury is then introduced into the containing-cylinder, and also there is added thereto a quantity of finely-divided particles of metal of a kind capable of being amalgamated by mercury-as, for instance, a metal such as silver or copper pre-' viously prepared in a comminuted, precipitated, or fine feathery condition and in quantity an amount in excess of the weight of metal contained in the ore or sufficient to approximately load the mercury, or, say, about two to five per cent., more or less, of added metallic particles to the Weight of the mercury employed. The container is again closed and the percussive action or agitation is then continued for about fifteen minutes, more or less, when the metals will be found to be amalgamated. The ore mass is then emptied from the container onto a screening device to separate out the pebbles, which may be returned to the cylinder when it is again charged. The amalgamated ore is conducted into a suitable settler for clearing it from the slimes.

The mercury, with the gathered gold and metals,when removed from the settler is subjected to a straining or squeezing operation to collect the amalgam and release the free mercury, which latter flows out of the squeezed mass without carrying With it more than a trace of gold and is then in a condition for further use, While the collected amalgam, which contains the gold and added metal, may be subsequently treated for separation of the several metals therein contained by any of the well-known methods employed for such purpose. The emptied cylinder or container can be recharged with ore, pebbles, and water and the circle of operations repeated, as before described. The function and effectof the added metallic particles is to gather the gold particles and make a body in the mercury sufficient to act as a scavenger and carry with it the gold liberated from the ore when the mercury is strained out and the amalgam collected. This addition of metallic particles may he made to theore at the beginning of the operation, but is not as desirable as to add the same later, the object being to add such metal particles at a point in the process where it Will be thoroughly incorporated with the ore and mercury, which is best accomplished by the mixing action of the moving pebbles.

The metal added as comminuted or precipitate particles is preferably of a metal of other kind than that sought to be recovered from the ore treated, copper or silver being the most convenient for the purpose. The copper or silver employed for the added or augmentation metal may in some instances, if desired, be used in the form of a previously-prepared amalgam of copper or silver in finely-divided or comminute particles.

This process is particularly well adapted for the treatment of ores of any grade that occur in a naturally soft or oxidized condition, especially those that are already finely commi nuted, as such ores may be charged at once into the container and the process carried out Without any preliminary breaking. In such cases a charge of several tons can be worked in about an hour, or even less, making the capacity of a singlecontainer or apparatus high and the working cost very low as compared with other milling processes. By this method very low grade ores can be profitably utilized,

since the process requires only simple machinery, while ordinary unskilled labor is sufficient to conduct the several operations, and the most active agent employed in the process-viz, pebblesare to be had for the mere gathering.

By my process the heavy particles. together with the float-gold contained in the ore, is saved, which is not the case in the ordinary milling practice, since in the latter such particles are buoyed up by the water and carried out with the tailings. Also by my method all rusty or coated grains of metal in the ore are freed from their envelop by the percussive and scouring action of the pebbles and are thus put into the best condition for quick amalgamation.

In treating by this process hard quartz or ores charged with sulfurets the ore is broken and crushed by any suitable means to about twenty mesh or more, and when charged into the cylinder together with the water'and pebbles, as previously mentioned, a certain quantity of milk of lime may be added, if desired, in quantities suflicient to neutralize any soluble sulfates that are present in the ore and the same operations gone through with as before stated. The employment of milk of lime is not necessary in all cases, but, as above noted, serves to assist without interfering with the essential features of the process. I find this addition of lime hydrate useful on all ores, particularly those containing clayey or talcy material, as its action coagulates such substances. and thus allows the mercury when added to play more freely through the charge and to separate more quickly and completely in the settler; but I am aware that lime hydrate has been used in other processes for treating ores, and I do not herein claim its use as of my invention.

In some instances, if desired, the quantity of comminuted or precipitate metal particles may be added to the mercury containing the gold amalgam after it has been gathered in mass or settled from the ore charge, but before it has been strained or squeezed. In such instances the added metal particles must be stirred into or thoroughly incorporated in and with the body of mercury in order that it may load itself with the added metal or metals, after which the mercury may be strained or squeezed out in Well-known Way, and the gold will be left in the grip of the added metal instead of a large percentage thereof going out with the mercury which is squeezed out, and it can be subsequently separated from the added metal, as before stated.

By this method it is possible to recover practically all the gold contained in a large body of mercury, as the residual mercury after the described treatment contains traces only of gold. Hence it will be seen that this is a very practical result and advantage where it is necessary to employ large quantities of mercury in the working of ores, since it is Well known that there is always a percentage of loss of the mercury employed, and such lost mercury always as previously employed takes gold or other values with it.

In addition to the advantages above enumerated I find that a large percentage of the silver present in the ore is saved by this process, which is not the case with the stamp-milling of ores.

I am awarethat ores have been treated in closed cylinders revolving on their major axis, together with broken rock, mercury, and other material; but such prior treatment does not mingle the ore contents in the manner described in my present process and is accordingly hereby disclaimed.

I am also aware that ores have been treated by a process where ore, water, mercury, and other substances are primarily mingled together at the beginning and requiring hours for its completion, which causes flouring of the mercury and results in large losses both of mercury and amalgam; but by my process the preliminary scouring and grinding to which the ore is subjected before adding the mercury and amalgamable metallic particles, as described, fully prepares it, so that the mercury is subjected to mechanical action but a short period of time, which is a very decided advantage as compared with the prior practice.

Having fully described my invention, what I claim, and desire to secure by Letters Patent, is 1 1. Theimprovement in the art of recovering gold or precious metals from a mass of ore under treatment by amalgamation with mercury; which consists in adding to a mass of metals and mercury, and collecting the amal-.

gam, substantially as set forth.

2. A process in the amalgamation of ores with mercury, which consists in loading the amalgamating medium subsequent to its absorption of the metal from the ore, with an added quantity of amalgamable metal particles in excess of the quantity of metal gathered from the treated ore, collecting the augmented amalgam from the free mercury and then separating the amalgam, substantially as set forth.

3. The process of recovering gold diffused in a body of mercury, which consists in adding to such mercury, in excess of the gold, a comminuted metal or metals other than that sought to be recovered, but capable of forming amalgam, that will act as a scavenger or gatherer for the gold when straining or squeezing out the mercury.

Witness my hand this 19th day of March, 1903.

GEORGE M. RICE.

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