Cadmium Mining
Cadmium Mining
Cadmium Metal:
Cadmium is a rare earth metal found along the ores of zinc. Even though greenokite (CdS) contains a major percentage of cadmium in nature, it is more associated with the zinc sulfide ores like sphalerite. The zinc ores consists only up to 0.3% of cadmium in it. A tiny amount of cadmium can be obtained from the byproducts of lead and copper. Some of the metallic cadmium is found along the Vilyuy river basin in Siberia.
Mining Of Cadmium:
The cadmium composing ore are mined by surface and underground mining methods. In surface mining or open pit mining the cadmium ore is excavated from the open pit mines. The cadmium ore is mined by the drilling the step walls of open pit mine which are specifically designed for vast excavation.
The larger ore bodies are blasted off and collected. The excavated ores of cadmium are transported by trucks to the primary processing unit on the ramps of mines. The open pit mining is a widely employed method for the ores found near the surface.
In underground mining, large machineries and shafts are used with much labor and cost. The underground mining for cadmium ore is initially started by taking the reports by analyzing the area; ore's quality and quantity; nearby places and expense for the overall mining process. Only if the reports qualify the needed requirements, a mine is established.
An underground pit is dug with shafts for moments of labour, machineries, excavated ores and air ventilation. The labors are equipped with strict safety measurements for avoiding hazards inside the pit. The cadmium comprising ores which are collected from underground mines will be of much greater quality than from open pit ones.
Extraction Of Cadmium:
The major extractions of the cadmium are done from the mined zinc sulphide ores. There are two steps of extraction considering the production of zinc. In pyrometallurgical smelting, the cadmium is separated by vacuum distillation and in electrolytic process;
cadmium is precipitated among the anode mud. For either of the process roasting of zinc sulphide ore is the initial step.Roasting of zinc ore in a concentrated high temperature converts zinc sulphides into impure zinc oxides.
By electrolysis:
The produced zinc oxide (ZnO) metal is made to undergo step by step electrolytic leaching process. At first it is leached with a dilute sulphuric acid solution (H_2 SO_4). At next it is leached with concentrated sulphuric acid (H_2 SO_4)solution.
The leaching process is completed when zinc is solved and other impurities such as cadmium, cobalt, nickel, copper, antimony and thallium are precipitated as a solid mixture. By further processing of that solid residue mixture cadmium sulphate is extracted.
By pyrometallurgical smelting:
The resultant zinc oxide (ZnO) metal is combusted with the presence of carbon in high temperature. In this process the metal reaches its boiling point and starts to vaporize. During this vaporization process at a certain equilibrium temperature cadmium alone vaporizes and collected. Then the collected cadmium vapor is further purified by vacuum distillation method. Cadmium produced from this method is only0.3%.
These are the two industrial techniques to extract and produce cadmium in bulk quantities.About 10% of the consumed cadmium is produced from the alternate sources such as dusts from recycling iron and steel.
China, Republic of Korea and Japan are the major producers of cadmium in the world. Aside them Canada, India, Kazakhstan and United States of America also contributes in the overall global production.
Cadmium:
Cadmium a rare earth metal found along the ores of zinc. Even though greenokite (CdS) contains a major percentage of cadmium in nature, it is more associated with the zinc sulphide ores sphalerite. The zinc ores consists only up to 0.3% of cadmium in it. A very tiny amount of cadmium can be obtained from the byproducts of lead and copper. Some of the metallic cadmium is found along the Vilyuy river basin in Siberia.
Extraction Of Cadmium:
The major extractions of the cadmium are done from the mined zinc sulphide ores. There are two steps of extraction considering the production of zinc. In pyrometallurgical smelting, the cadmium is separated by vacuum distillation and in electrolytic process; cadmium is precipitated among the anode mud. For either of the process roasting of zinc sulphide ore is the initial step. Roasting of zinc ore in a concentrated high temperature converts zinc sulphides into impure zinc oxides.
By Electrolysis::
The produced zinc oxide (ZnO) metal is made to undergo step by step electrolytic leaching process. At first it is leached with a dilute sulphuric acid solution (H_2 SO_4). At next it is leached with concentrated sulphuric acid (H_2 SO_4)solution. The leaching process is completed when zinc is solved and other impurities such as cadmium, cobalt, nickel, copper, antimony and thallium are precipitated as a solid mixture. By further processing of that solid residue mixture cadmium sulphate is extracted.
By Pyrometallurgical Smelting:
The resultant zinc oxide (ZnO) metal is combusted with the presence of carbon in high temperature. In this process the metal reaches its boiling point and starts to vaporize. During this vaporization process at a certain equilibrium temperature cadmium alone vaporizes and collected. Then the collected cadmium vapor is further purified by vacuum distillation method. Cadmium produced from this method is only0.3%. These are the two industrial techniques to extract and produce cadmium in bulk quantities. About 10% of the consumed cadmium is produced from the alternate sources such as dusts from recycling iron and steel. China, Republic of Korea and Japan are the major producers of cadmium in the world. Aside them Canada, India, Kazakhstan and United States of America also contributes in the overall global production.
Applications:
About three-quarters of the cadmium used in batteries, mainly in rechargeable nickel-cadmium batteries. Nickel-cadmium cells have a supposed cell potential of 1.2 V. The cell consists of a positive nickel hydroxide electrode and a negative cadmium electrode plate divided by an alkaline electrolyte. More recent nickel-metal hydride batteries reduce the use of Ni-Cd batteries.
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