Electrolytic Precipitation of Gold
In order to perform the electrolytic precipitation of gold, from the filtration vessel the gold chloride solution was conducted into the outer or battery jar of an electrolytic cell. The electrode of the outer cell was connected with the negative pole of a dynamo and the electrode on the inner cell was connected with positive pole or terminal of the dynamo. The gold solution was sent into the jar near the bottom and slowly circulated upwards, and at the same time a current of electricity was passes through the cell. When the reaction was produced, the gold chloride was decomposed and felt like a shower of fine spangles to the bottom, while the liberated chlorine passed into the inner cell where it was absorbed by the water circulating and formed a chlorine solution.
The receiver was charged with chlorine solution generated by the electrolysis of salt. The unit comprised a battery, a conductor from the electrode in the large battery jar to the negative pole of the electrical generator, the conductor from the electrode in the porous cell to the positive pole of the generator, a reservoir containing a saturated solution of sodium chloride, which passed to the battery through a pipe and a reservoir containing water connected by a pipe with a porous cell.
In order to treat the ore more effectually with the chlorine solution it was advantageous to expel the air from the chlorinator. For this purpose the chlorinator was provided with a valve, so that the air contained in the chlorinator passed out as the chlorine solution passed in. the valve was closed immediately the air was expelled. The chlorinator after disconnected was slowly revolved by means of a pulley and strap from an engine, or in other suitable way until the gold was dissolved as a gold chloride. The time required for treatment in the chlorinator varied from one to two hours according to the characteristics of the gold ore treated. The ore and solution were discharged into a suitable filtration vessel placed beneath the chlorinator. The vessel was a shallow vat constructed of oak or other material, the lower part was made cone-shaped and of the same capacity of the chlorinator.
The vat was closed by a cover bolted down. In the center of the cover there was hopper-shaped inlet for receiving the ore and solution from the chlorinator. A perforated diaphragm covered with asbestos cloth, over which was advantageously placed a layer of other suitable filtration media such as ground asbestos, which was fixed from one to two inches below the top of the vat. The gold chloride was washed out of the ore by a stream of water from a tank. The water entered the vat through a pipe at the lowest part and percolated upwards through the ore until the gold content in the solution was extremely low. It was important to take samples of the solution to determine the presence of gold. A sliding door in the bottom of the vat was opened and the residue from the ore as discharged by means of a large outlet opened into a truck placed underneath.
The gold chloride and water descended through a pipe into a receiver and was conducted from the receiver into the outer or battery jar of the electrolytic cell. The gold solution flowed into and entered the jar at the bottom and slowly circulated upwards and at the same time a current of electricity was passé through the cell to reduce and precipitate gold from the solution into a perfectly pure state, upon the bottom of the jar, from where it was removed. The chlorine was liberated at the same time at the electrode in the inner or porous cell and in contact with the water circulating and formed a chlorine solution, which was sent to receiver vessel.