US861535A - Process of treating ores. - Google Patents

Description

- NI ED STATES PATENT OFFICE.

LOUIS M. :PRITOHARD, or BOISE, IDAHO.

PROCESS OF TREATING ORES.

Specification of Letters Patent.

Patented July so, 1' 907.

Application filed June 26, 1906, Serial No. 323,521-

pectors in the field for testing ores are not well adapted to the testing" of ores generally, but more especially base and low grade ores. To ascertain the value of his samples it is usually necessary for the prospector to send them to an assayer, who is often located at a distant point, and to have a reliable report numerous assays are required. This method is not only costly but requires considerable time in sending the samples and waiting for thereturns. I

The present invention has for its object the provision of a process whereby the prospector himself can make the tests of'his ores for gold in the field, make as many as he desires, and do so atvery great saving of expense and time; and also by means of which he can arrive at a'fair, approximation of the gold .valueof his. ores.

The process is only adapted to the testing and reduction of auriferous ores and will be described as so ap- It is 'well known that the elements of the halogen group are solventsof gold, and of these, iodin is the most stable, has the least affinity for hydrogen, dissolves fewer substancesother than gold, and isleast liable to .injuriously affect those who handle it. In the present invention it is proposed to take advantage of the properties of iodin in a process-for treating auriferous ores, particularly for assaying purposes. Iodin mixed with 1 potassium iodid can be easily carried by the pr0spector asa part of'his outfit as dry salts, to which he can add water to make the solvent solution when he desires 'tion of iodin to dissolve the gold and adding mercury to the solution to form an amalgam and then separating the gold from the mercury.

In carrying out the process the] ore. is ground very fine and screened to remove. the Eoars'er particles.

Previous to grinding most ores. can be roasted to advantag e, thus freeing the ore of most of the interfering elements, makingit more porous,-so that the gold is more I easily leachedbut; some ores however, such a'sthose cuntaining galena; can be better treated withoutthe I preliminaryroasting. The pulverized ore' is treated red color of the solution disappears.

with an excess of a solution of iodin dissolved in potassium iodid in an aqueous solution. The solution is added until the mixture retains a dark red color. While the ore is being acted on by the solvent the grinding can be continued at intervals to remove any slimes or precipitates that may coat the particles'and thereby permit the solution to act directly upon the gold particles. After the ore has been acted upon for a suflicient length of time, depending upon the quantity. and

- fineness of the gold in the ore, the solution is separated from the pulp. To obtain all of'the solution it may be washed from the pulp with water. After the solution has been separated from the pulp, mercury is added and the mixture is vigorously agitated until all of the If sufiicient mercury has been added, and it is better that it shouldbe too much rather than too little, the liquid gradually clears and the mercury flours and sometimes turps black, when all of the gold will be found amalgamated with the mercury. The mercury reduces the gold in solution to the metallic state and immediately forms an amalgam with it. The excess of iodin andpotassium iodid in the solution, aidsgreatly in thus collecting the gold by its action upon the mercury principally by causing it to break up and flour during the agitation, thus exposingavery large surface of the mercury to act upon the'gold in solution, causing its amalgamation very quickly. The amalgam is then washed to free it from the solution and other extraneous matter. Finally the gold andmercury are separated by distillation or by treating the amalgam with nitric acid to dissolve out the mercury and other impurities if any. It is preferable to dissolve with nitric acid for the reason that it leaves the gold in a pure state, and when small quantities are taken it willbe in the shape of a small gold button, inconvenient form to be measured 'or weighed.

While the process has been particularly described as being adapted to the use of the prospector, .yet it can be used on a large scale for the commercial reduc-'' tion of ore. I

Having thus described my'invention, what I claim and desire to secure by Letters-Patent is, a,

1. The process of treating ores consisting in dissolving" the gold in the ore in a solution of iodin, adding mercury to the solution to form an amalgam, and separating theamalgam into its componentparts. 1 2. The process of treating auriiferous ores consisting in pulverizing the ore, tree-ting it with iodin dissolved in an aqueous solution of potassium iodid to dissolve the gold, agitating the solution thus Iforrnedwith mercury to form an amalgam with the gold, and separating the gold from the mercury.

In'testimonywhereof I- have "hereunto aflixed my slgna turejn thepresencemf two witnesses. 1 F LOUIS Mi PRITCHARD.

witnesses:

ALFRED ihrnrnnu, K

CHABLEsL. LiNGnNr-ufirnn.