The copper era., 1909-08-26

nyQrOSen gas ODCdlneQ rom the dDOVe reactions is treated in the following manner:
 A given amount of sulphuretted hy- drogen gas is taken from the storage tank and burned with air in a suit able burner, forming sulphur dioxide, which passes into condensing chamber.
 An equal amount of sulphuretted hydrogen gas from the storage tank is now pumped into the condensing chamber and allowed to react with the sulphur dioxide, resulting in the precipitation of sulphur in the form of a fine powder.
 Operation ''D". The electrolytic precipitation of the copper is carried out in suitable precipitating tanks, arranged one below the other in cas- cade form, and in which are cer- tain number of carbon or graphite plates, which act as anodes, and a certain number of thin copper plates, which act as the cathodes. Each tank has a few more electrodes than the one above it, or, in other words, the square inches of electrode sur face in each tank increases the lower tank. The copper solution flows into the upper tanks and between the electrodes, then overhows through a pipe into the second tank, and so on to the last tank.
 The solution in flowing through the tank, is subjected to an electric cur rent of the proper electro-motive force and current density, resulting in the precipitation or deposition of the copper upon the thin copper cathodes in a refined condition.
 In order to electrically deposit cop per from it's solutions, using an in- soluble anode and obtain a firm, solid deposit of metal, it is necessary to decrease the current per square inch, as the per cent of copper in solution decreases. In this process this is ac- complIshed by increasing the cleo trode surface as the copper in solution decreases, thereby decreasing the current per square inch.
 By this arrangement a constant current Can be maintained of the same amperage in all tanks, regard less of the per cent of copper in SO lution. The solution passing from the bottom tank, and which has been deprived of most of its copper, flows into stump tank, from where it is pumped back to be used over again.
 In order to more fully illustrate the different important features of this process and the reactions that occur, the treatment of complex sulphide of copper, lead, arsenic and antimony will be taken as an example.
 The per cent of each element con- tained in the ore is not given, as this is immaterial in showing the re- actions taking place.
 Operation "A". The ore is'crushed to about 20 mesh, and a certain amount is placed in the reduction tank and on top of the carbon or copper cathode. The ore is then cov- cred with a solution of hydro-Auor-- silicic acid of about 10 per cent strength; enough solution being add ed to reach above the ore to height of IS to 24 inches. The carbon an odes are placed in position, allowing about inches immersed in the solu- tion, but not touching the ore. The metallic hood is then placed over the carbon anodes and in such a manner that the gases evolved will collect in the top of same. An outlet pipe, leading from the hood, is connected to a pump, in order to withdraw the gases generated. The carbon anodes and cathodes are then connected to an electric generator and the electric current caused to flow from the car bon anode through the electrolyte to the ore and cathode. An electro-mo- tive force of about four volts is used with a current strength depending upon the size of the tank and amount of ore to be treated.
 The passing of the electric current through the electrolyte causes de- composition of the water into its component parts, oxygen being evolved in and on the body of ore, which acts as a secondary cathode.
 The disengaged electrolytic hydro gen unites with the sulphur of the ore, forming sulphurette hydrogen gas, which is drawn out of the tank by the pump. The arsenic combines with the electrolytic hydrogen, form ing arseniuretted hydrogen, other wise known as arsenic. The anti mony likewise combines with the electrolytic hydrogen, forming sti- bine.
 The sulphuretted hydrogen, arsene and stibine are pumped into a stor- age tank for further treatment.
 At the end of this operation there is left in the bottom of the reduction tank and in contact with the copper or carbon cathode, metallic copper and metallic lead in a spongy condi- tion, the sulphur, arsenic and anti mony having been eliminated in a gaseous condition in the manner