The successful development of the Cyprus Copper Process has been an evolutionary series of events covering a time span of some seven years. What does the Cyprus Copper Process do? Very simply, it converts copper concentrates of varying composition into copper metal which has been proven to be equivalent in every way to electrolytic tough pitch copper suitable for electrical applications. This is accomplished at capital and operating costs which are estimated to be lower than those associated with any other known currently applicable technology. Also the total energy requirement is equal to or less than any other known process and the process is pollution-free.
Simply stated, copper concentrates are dissolved in a ferric chloride-copper chloride solution in two stages of leaching. The pregnant solution from the first leach is high in
cuprous ion concentration. This solution is cooled and cuprous chloride crystals are precipitated. These crystals are washed, dried and fed to a fluidized bed where hydrogen reduction takes place, copper nodules are produced which are suitable for melting, fire refining and casting into wirebars the fluidized bed also produces HCl.
LEACH I
- 4FeCl3 + CuFeS2 → 5FeCl2 + CuCl2 + 2S°
- 3CuCl2 + CuFeS2 → 4CuCl + FeCl2 + 2S°
- 6CuCl2 + S° + 4H2O → 6CuCl + H2SO4 + 6HCl
LEACH II
- CuCl + FeCl3 → FeCl2 + CuCl2
- 4FeCl3 + CuFeS2 → 5FeCl2 + CuCl2 + 2S°
METAL REDUCTION
CuCl + ½H2 → Cu° + HCl↑
Feed – concentrates are fed to the plant as received from the concentrator filter plant. Since the process depends on a steady copper feed rate, the feed system must be capable of accurate weight control, also current
grade and moisture analyses must be available at all times. Concentrate is fed to a mix tank where it is mixed with recycle leach liquor from the second leach. The slurry is fed to the first stage leach, consisting of four agitated tanks in series. These are equipped with internal heat exchangers for precise temperature control. The first leach has two functions.
Crystallization takes place in a single stage vacuum cooler. The hot leach liquors are flashed to a temperature of 100°F, which lowers the cuprous solubility, precipitating copper chloride crystals. Vacuum is maintained by steam jets which remove non-condensable gases. Water which is evaporated in the crystallizer is collected in a barometric condenser. Cuprous chloride slurry is drawn off the bottom of the crystallizer and pumped to a centrifuge. The cake is washed, dried and held for feed to the fluid bed reactor.
