“An a naturally occurring substance present in rocks and ground that has its own chemical composition is called a mineral.” e.g. diamond, quartz, garnet, etc.
“A type of mineral from which metal is obtained is called ore.” OR Impure form of metal is called ores. e.g. hematite, bauxite, chalcocite, etc.
“A metal in a free state is called native metal.”
“A metal in the combined state is called compound metal. It is also called mineral”
“The unwanted impurities present in an ore are called gangue.”
Q.2: Define metallurgy. What are its steps?
“The art and science of making metals and alloys from their ores is called metallurgy.” OR
“The extraction of metals from their ore and conversion of them to alloys is called metallurgy.”
Basic metallurgical operations/steps:
During metallurgy the following general steps are carried out which are tailed basic metallurgical operations:
Grinding and crushing
Roasting and calcination
Smelting and reduction
Q.3: Describe the basic metallurgical operations in detail.
Ans: Basic metallurgical operations:
Basic metallurgical operations are the various physical and chemical processes by which metals are not only extracted from their ores but also made suitable for use. Metals are extracted from their ores by different methods.
The selection of the method depends on;
a. Type of ore i.e. oxide, carbonate, etc.
b. Reactivity•of metal
c. Nature of gangue present in the ore.
During metallurgy the following general steps are carried out which are called basic metallurgical operations:
ii. Grinding and crushing
iv. Roasting and calcination
v. Smelting and reduction
They’re the detail is given below:
Extracting ores from the ground by digging the earth is called mining.
The ore contains a large amount of gangue or useless rocky portion. In order to remove a sufficient amount of gangue, the concentration of ore is carried out. Various methods are used for the concentration of ore these include grinding and crushing, gravity separator, froth floatation process, etc. The detail is described below:
a.Grinding and crushing:
The ore obtained by mining consists of large pieces. In this step, the ore is converted into small pieces with the help of grinders and crushers. These small pieces are then converted into a fine powder with the help of a ball mill or stamp mill. This process is called pulverization
b. Gravity separation (Hydraulic washing):
This method is based on the difference in densities of ore and gangue. In this method, the ore containing gangue is poured over a hydraulic classifier. The hydraulic classifier is a vibrating inclined table with grooves. Then a jet of water is allowed to flow over the ore and gangue. The ore particles are denser, they settle in grooves while the lighter gangue particles are washed away.
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