US546113A - Process of depositing gold from its aqueous solutions - Google Patents

Description

(No Model.) I 2 Sheets-Sheet 1.

e H. K. B. DAVIS. PROCESS OF- DEPOSITING GOLD FROM ITS AQUEOUS SOLUTIONS.

No. 546,113. Patented Sept. 10,1895.

'W-ITNESSESL INVENTOR ANDREW 5.6RAI1AM.PHOTDUTHQWASNINGTONDC v v 2 Sheets-Sheet 2.

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H. K. B. DAVIS. mocnss 0F DEPOSITING GOLD FROM ITS AQUEOUS SOLUTIONS.

No. 546,113. PatentedSept. 10, 1895.

ANDRlW BJZRANANL PNOTWUDIQWASNINQTDN D C HENRY K. B. DAVIS, or PHILADELPHIA, PENNSYLVANIA.

PROCESS OF DEPOSlTlNG GOLD FROM ITS AQUEOUS SOLUTIONS.

SPECIFICATION forming part of Letters Patent No. 546,113, dated September 10, 1895.

Application filed April 25, 1895. Serial No.'547,116. (No specimens.)

To all whom it may concern.-

Beit known that I, HENRY K. B. DAVIS, of the city of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in the Process of Depositing Gold from itsAqueous Solutions, of which the following is a specification.

The accompanying drawings illustrate two types of apparatus adapted to the conduct of my process, Figure 1 being a vertical central section through a preferred form of such apparatus, and Figs. 2 and 3being, respectively, a partial vertical central section and a transverse section of a modified form, the sectional plane of Fig. 3 being indicated by the lines 3 3 in Fig. 2. It must be understood, however, that the invention is not restricted to the employment of these or any particular form of apparatus, and that the types shown in the drawings are merely for convenience of illustration.

My improvements relate particularly to that process of depositing gold which consists in subjecting the solution of its chloride or chlorides, to the action of carbon, substantially in the manner set forth in Letters Patent of the United States No. 227,963, dated May 25, 1880. I have discovered that the rapidity and completeness of deposit of the gold upon the carbon can be enormously increased by diffusin gfree hydrogen gas through the gold solution during, or just previous to, its passage through the carbon, and the utilization of this discovery, in an organized man ner, constitutes the subject of my invention.

I will now proceed to describe, by reference to Fig. 1 of the accompanying drawings, a convenient and economical method for the application of my process. In said figure, A

represents a cylind rical vessel, usually of iron,

having alead1ining,(indicated at a.) Said vessel is provided near its bottom with an outlet pipe 13, controlled by means of a stop-cock b,

and is also provided with an inlet or deliverypipe 0, similarly controlled by the stop-cock O, and leading from any convenient source of supply of the gold solution. The vessel A is partly filled with carbon, as indicated at D, charcoal in small pieces of uniform size being preferably employed for this purpose. Upon the top of the mass of charcoal is a perforated leaden plate E, whose purpose is to prevent too great disturbance of the charcoal by the inflowing liquid, and above said plate is a layer of zinc shavings F.

The solution of gold chlorides which I employ usually contains an excess of chlorine, and also, as an incident of manufacture, a slight excess, say one per cent, of free sulphuric acid. In cases, however, where such percentage of sulphuric acid is lacking, and where the above-described apparatus is to be employed, such acid should be added in about the proportion above mentioned. This solution is run into the vessel A and allowed to pereolate down through thelayer of zinc shavings F, and thence through the mass of charcoal D, the filtered liquid being finally discharged at theoutlet-pipe B. In practice I prefer to admit the solution in sufficient quantity to keep the layer of zinc shavings entirely submerged, as indicated at G. Thereactions which occur I believe to be as follows:

The attack of the sulphuric acid upon the zinc shavings is attended with an evolution of hydrogen gas, which immediately combines with the chlorine in the gold solution to form hydrochloric acid, thussetting free the metallicgold, which is deposited in the usual manner upon the surface of the charcoal. The resultant sulphate of zinc and hydrochloric acid both pass away in aqueous solution through the charcoal and are discharged at the outlet-pipe B.

To guard against any possible loss of gold by reason of a too free or rapid passage through the charcoal, I prefer to discharge the liquor from the above-described vessel into another similar one; but this, of course, is a mere detail of practice and need not be further described.

It will be noted that in the above application of my process I provide a means for directly generating hydrogen gas from the water of the gold solution itself at the moment of its entry into the charcoal, and that, incidentally, I take advantage ofa usual ingredient of the chloride solution.

Vhile I deem this application of my process the most economical and convenient for use, I do not limitmy claims thereto, as it is obvious that a similar reaction could be obthe rate of percolation.

tained by generating the hydrogen gas elsewhere and admitting it to contact with the gold solution, either during the passage of the latter through the charcoal, or as the immediate preliminary to such passage, the only limitations in this direction being economical and convenient conditions of manufacture. Thus in the type of apparatus shown in Figs. 2 and 3, A indicates the vessel containing carbon D, a being the lead-lining of the vessel. Immediately above the mass of car bon is a spiral coil of lead pipe H, having numerous fine perforations h. Said pipe 11 leads from a generator I, located at any con- Venient point in which hydrogen gas is to be developed by any convenient process, with a pressure and volume sufficient to cause the discharge of the gas throughout the perforated portion of the pipe H. The gas thus escaping permeates the gold solution, (indicated by the dotted lines in the upper portion of the vessel A,) which solution is of course supplied through the pipe C in conformity with It is of course desirable to diifuse the hydrogen throughout the solution to the greatest possible extent, and to this intent a perforated pipe, similar to the pipe H, may be with advantage located within the feeding-reservoir for the solution, the hydrogen from a generator, such as I, being freely admitted through the same.

I do not claim, broadly, the use of hydrogen gas to decompose gold chlorides, for I am of course aware that, as a matter of laboratory knowledge, its capacity to do so has been recognized. For commercial purposes, however, such method is not practicable, and it is only by reason of the organized employment of hydrogen treatment in combination with the carbon process, as herein set forth, that the properties of hydrogen in this respect become substantially available.

Having thus described my process, I claim- 1. As an improvement in the process of depositing gold from the aqueous solution of its chloride,the hereinbefore described process of diffusing hydrogen gas through said solution and passing said solution through carbon, substantially as described.

2. The hereinbefore described process of depositing gold from the aqueous solution of its chloride, which consists in forming an acid excess in said solution; passing said solution over a metal, such as zinc, and thereby generating hydrogen gas in said solution, and then passing said solution through carbon, substantially as described.

HENRY K. B. DAVIS. \Vitnesses:

JAMEs H. BELL, G. HERBERT JENKINS.

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