Home > Technology > Manufacturing Tech > Electrolytic Refining In the electrochemical process, chemical energy from materials and exterior electrical energy are converted to generate electro-chemical reactions through the outside electric circuit. Electrochemistry is divided into Ionics, Inferfacial Phenomena, and Electrodics. ¨ç Ionics: refers to the movement of ions, ion equilibrium, ion yields, reversible electrode dislocation,      and hydrogen ion density within the solution or molten salt ¨è Inferfacial Phenomena: the electro double layer phenomenon, adsorption theory, electrochemistry velocity,      switch, ion exchange process ¨é Electrodics: the velocity effect mechanism of electrodics, electronic movement, electro-catalytic process The area that applies to electrochemical phenomena is the chemical industry. Specifically, those industries that use electrochemical energy. (Example: the refining industry in which heavy metals such as crude copper, which is low in purity, are electrolyzed to refine metals) The flow of electrons is an electric current and electricity flows from cathode to anode. However, generally the direction of the electric current is flows in the opposite direction from the flow of electrons. The size of the charge is the amount of electrons that passes over a surface in 1 second. The size of the electric current when 1C of electrical charge flows for 1 second is called 1A (ampere). Electric currents flow when pressure is applied and such electrical pressure is called voltage, denoted as V. Every material obstructs the flow of electric currents. This obstruction is called electric resistance. The size of resistance is measured in ohms (¥Ø). According to Ohm's law, the size of the electric current that flows between two conductors is proportional to the voltage between the two points and is inversely proportional to resistance. If a current of I (A) flows for t(s) at a resistance of R (¥Ø) then heat energy (H) is H = I©÷Rt (J) If this heat energy, H (J), generated from electric energy, Is applied to voltage at a resistance (R)V, Ohm's law gives us the following equation: W = H = I©÷Rt = (IR)It = VIt(J) Electric power is used for measuring how much electricity is consumed per unit of time and work done. A Watt (W) is the power supplied or consumed for 1(s) and 1(W) is 1(J/s). The following feature is related with the amount of heat generated when a current flows through a certain resistance. When a current of I (A) flows through a conductor at a resistance R(¥Ø) for t(s) then heat(H) is generated in the conductor. H = I©÷Rt(J) This is Joule's law and the generated heat is called Joule's heat. Calories are also frequently used as a unit of heat instead of Joules (J) (1 cal = 4.186J). Copper sulfate (CuSO4) dissolves in water and is separated into +ions and -ions. Such a process is called ionization. Electrolytes and copper sulfate dissolve in water and generate electrolytes. The process by which a chemical reaction occurs when an electric current flows through electrolytes is called electrolysis. When two copper plates are inserted into the electrolytes of copper sulfate as electrodes and a power source is connected, the A (anode) copper plate becomes thinner and the K (cathode) copper plate becomes thicker. That's because the copper that has dissolved from the anode becomes the Cu©÷+ ions and they are attracted to the cathode by providing a positive electric charge to the plate. From electrolysis experiments, Faraday discovered the following laws: * The amount of materials extracted from electrolysis is proportional to the amount of electricity that passes through the electrolytes. * If the total amount of electricity that passes through the electrolytes is equal to the amount of materials extracted from electrolysis, the amount is proportional to the chemical equivalent. (chemical equivalent = atomic weight/atomic velocity) The electrolysis of solutions that contain metallic ions is used for refining metals or extracting metals from leached solutions. The solution that contains metallic ions is electrolyzed and extracted in the metallic state, and it's also possible to extract electrolyzed metals from mixed solutions by using the potential difference between electrodes among various metals. The anode becomes ionized after being dissolved electrochemically by the electrolytes and possitive ions move to the cathode, finally being extracted as metal. Anode copper generated by the smelting process contains impurities such as Au, Ag, Pb, Zn, and Fe. Copper is refined by electrolysis and these impurities are recycled as anodic slime at the same time. It is electrolyzed using a copper sulfate (CuSO4) solution as an electrolyte at a temperature between 55 and 65¡É. There are two processes in electrolytic refining. One is the conventional process where a thin pure copper plate (99.99% ¡è) is used as a starting sheet. The others are the ISA and KIDD processes where a STS plate is used as a cathode. The Electrode reaction. Main impurities in anode copper are Ag, As, Au, Bi, Fe, Ni, Pb, S, Sb, Se, and Te. Anode (refined blister copper) and cathode (STS plate) are inserted into the commercial cell (see above figure) that produces electrotic copper. It is arranged such that the distance between the anode and the cathode pitch is 98mm. Anodes in a cell are put on the positive pole and cathodes are put on the negative pole. Electricity flows from the anode (+) to the cathode (-) through electrolytes mainly composed of CuSO4. At this time, Cu out of the anode copper located in the anode (+) is deposited electrically on the STS plate, and the cathode (-). It is designed so that a constant amount of electrolytes flow into each commercial cell continuously. Heat exchange is provided to maintain the temperature of electrolytes and there is equipment for adding additives. Some of the electrolyte is bled into the purification process and copper and impurities are removed. When electrolytic copper is produced, general anode copper made in a furnace is used and a STS Plate (Blank Cathode) is used as a cathode. These are inserted into the commercial cell and electrolytic copper is produced after a 7-day electrolysis. For anode copper the anode is pulled out after 21 days. It is called anode scrap and retreated as cold material in a converting furnace. Also when electrolytic copper is pulled out, anodic slime attaches to the scrap anode. Because many precious metals are included in this anodic slime, it is sent to the precious metal plant after removing Cu.