US1103346A - Recovery of gold and silver from refractory ores. - Google Patents

Description

CHARLES senses, or Lennon, ENGLAND.

RECOVERY or GOLD Ann sitvmt monmsaacmom ORES.

No Drawing.

To all whom it may concern:

Be itknown that I, CHARLns Burrnns, a citizen of the United States of America, residing at London, England, have invented certain new and useful Improvements in increased, time is saved and so is also the cyanid or other solvent which may be employed in the final recovery" of the precious metal.

The invention is based on a reaction which it has been found occurs when sulfid gold and silver ores, tellurids, and similar ores associated with, or not associated with, arsenic, antimony and the like are brought into intimate contact such as by agitation or otherwise with certain metals such for example as aluminium, zinc, tin or palladium, in any convenient form, but preferably as metallic surfaces, in the presence of caustic soda or other caustic alkalis, either hot or cold, which results in such ores being decomposed and the metallic gold and silver being freed from combination with the sulfur or the like whereby they are in condition to be readily attacked or dissolved by potassium cyanid or other suitable solvents.

According to the invention, the ore is first finely crushed or ground in the presence of a solution of caustic soda or other caustic alkali and the solution with the ore is then run into tanks from which firstly the excess of the solution may be decanted. The ore with sufficient electrolyte consisting of the caustic soda solution (of say 3/10% strength) to form a thick pulp is then agitated in such tank, or it may be in a separate tank or tube mill if the first is not provided with an agitator. Such agitating tank may be lined with one of the metals referred to, say aluminium or it may contain or carry blocks or plates of the metal, the agitating element being also preferably of the same metal, viz., aluminum. Under these conditions an electric current is set up between the aluminum and the ore under treatment, the aluminum acting as the anode and the ore as the cathode, which latter,

Specification of Letters Patent.

probably principally throughthe agency of nascent hydrogen, is then split upinto its component parts, and the precious metals left free to be acted onby cyanid or other suitable solvents;

The following equations will serve as eX- amples to illustrate the reactions involved 1n this process:

A. Argeatz'te, (Ag S.l) 2Al'-[-2NaOH+2H,O:Na Al O,+6H. e1i+sii .'s+6NaoH':

3Na S+6H O+6Ag Since there is always an excess of caustic alkali present, the H S is immediately transformed into sodium sulfid as follows:

In this case some of the arsenic goes into the solution in the excess of the caustic alkali, but most of this will be precipitated out again by the aluminum if the treatment is continued long enough. For purposes of the subsequent'cyanid treatment it is immaterial'which of the two courses is followed by the arsenic.

U. Pymrgym'te, (A SbS The same remark will hold good here as applies above in the case of arsenic.

D. Gold tcllum'd, say, (AuTe From time to time the pulp is sampled and when decomposition is sufficiently complete, it is withdrawn, filter pressed and the caustic soda or like alkaline solution returned to the crushing plant. The filter pressed ore is then with or without washing, extracted with cyanid solution by the wellknown cyanid process, or is otherwise treated with a suitable solvent, the gold or silver being precipitated by zinc in the usual way.

Patented July 14, 1914:.

Application filed August 28, 1912. Serial No. 717,499.

What I claim is: 1 1. The process of treating refractory gold and silver ores which consists in subjecting said ores in a finely divided Condition to the action of nascent hydrogen produced in solut-ion during the reaction.

2. The process of'treating refractory gold and silver ores which consists in agitating the said ore whereby it is subjected to the action of nascent hydrogen produced in the solution of which the ore forms a part dur ing the reaction.

8. The process of treating refractory gold and silver ores consisting in subjecting the gold to the action of a metal in the presence of caustic alkali.

4:. The process of treating refractory gold and silver ores consisting in subjecting the ore in the presence of a metal having the property for the required reaction of aluminium to the action of caustic alkali.

5. The process of treating refractory gold and silver ores consisting in subjecting the ore to the action of metallic aluminium in the presence of caustic alkali.

6. The process of treating refractory gold and silver ores consisting in subjecting the ore to the action of metallic aluminium in the presence of a solution of caustic alkali.

.7; The process oftreating refractory gold and silver ores consisting in subjecting the ore'to the action of a metal by agitation in the presence of caustic alkali.

8. The process of recovering gold and silver from refractory ores, consisting in crushing the ore in the presence of a solution of caustic alkali, then agitating the ore with suflicient of the solution to form a thick pulp in the presence of a metal, then extracting the decomposed residue from the alkali solution, and then subjecting such residue to the action of a solvent to extract the precious metal.

9. The process of recovering gold and silver from refractory ores, consisting in crushing the ore in the presence of a solution of causticalkali, then agitating theore with sufiicient of the solution to form a thick pulp in the presence of a metal having the properties for therequired reaction of aluminium, then filter pressing the decomposedresidue to extract it from the alkaline solution,

and then subjecting such residue from the alkaline solution, and then subjecting such residue to the action of a solvent to extract the precious metal. i

10. The process of recovering gold and silver from refractory. ores, consisting in crushing the ore in the presence of a solution of caustic alkali then agitating the ore with sufficient of the solution to form a thick pulp in the presence of fixed and moving.

surfaces of a metal having the properties for the required reaction of aluminium, then extracting the decomposed residue from the alkaline solution, then subjecting such residue to the action of a solvent to extract the precious metal and then precipitating the latter. x

.In witness whereof I have hereunto set my hand in the presence of two subscribing witnesses. p

7 CHARLES BUTTERS. Witnesses:

M. C. HUMPI-IRIES, ALLEN CARY J ONES.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner 01' Patents,

Washington, D. 0. i