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प्रश्न
Describe ‘froth floatation process’ for concentration of sulphide ore.
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उत्तर
Froth floatation process:
1) Froth floatation process is based on the principle of difference in the wetting properties
of the ore and gangue particles with water and oil.
2)It is used for the extraction of those metals in which the ore particles are preferentially
wetted by oil and gangue by water
3) This method has been used for removing gangue from sulphide ores. eg. Galena (PbS), zinc blende (ZnS), copper pyrites (CuFeS2), etc.
4)In this method, a suspension of the powdered ore is made with water. To this suspension small quantities of collectors and froth stabilizers are added. Collectors (eg. pine oil, eucalyptus oil, fatty acids, xanthates, etc.) enhance non-wettability of the
mineral particles and froth stabilizers (eg. cresols, aniline) help in stabilization of the
froth. The mineral ore particles become wet by oil, while the gangue (impurities) particles by water.
5)In the floatation tank, a current of compressed air is circulated through the water. A
rotating paddle agitates the mixture and draws air into it. As a result, froth is formed
which carries the mineral particles. The froth is light and is skimmed off. It is then
dried for recovery of the ore particles. The gangue material is wetted by water and
settles at the bottom.
6) In the floatation tank, a current of compressed air is circulated through the water. A
rotating paddle agitates the mixture and draws air into it. As a result, froth is formed
which carries the mineral particles. The froth is light and is skimmed off. It is then
dried for recovery of the ore particles. The gangue material is wetted by water and
settles at the bottom.
7)Sometimes, it is possible to separate two sulphide ores by adjusting proportion of oil to
water or by using ‘depressants’. eg. In case of an ore containing ZnS and PbS, the
depressant used is NaCN. It selectively prevents ZnS from coming to the froth but
allows PbS to come wi th the fr oth, whi ch can be further removed.
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संबंधित प्रश्न
Explain:
Zone refining
Name the common elements present in the anode mud in electrolytic refining of copper. Why are they so present?
Outline the principles of refining of metals by the following method:
Vapour phase refining
Write the chemical equations involved in van Arkel method for refining zirconium metal.
Write the principle behind the following methods of refining:
Vapour-phase refining
Electrolytic refining is used to purify which of the following metals?
In which of the following method of purification, metal is converted to its volatile compound which is decomposed to give pure metal?
(i) Heating with stream of carbon monoxide.
(ii) Heating with iodine.
(iii) Liquation.
(iv) Distillation.
In the extraction of chlorine from brine:
(i) ∆GΘ for the overall reaction is negative.
(ii) ∆GΘ for the overall reaction is positive.
(iii) EΘ for overall reaction has negative value.
(iv) EΘ for overall reaction has positive value.
How are metals used as semiconductors refined? What is the principle of the method used?
Give two requirements for vapour phase refining.
Match the items of Column I with the items of Column II and assign the correct code:
| Column I | Column II |
| (A) Coloured bands | (1) Zone refining |
| (B) Impure metal to volatile complex | (2) Fractional distillation |
| (C) Purification of Ge and Si | (3) Mond Process |
| (D) Purification of mercury | (4) Chromatography |
| (5) Liquation |
Assertion: Zirconium can be purificed by Van Arkel method.
Reason: ZrI4 is volatile and decomposes at 1800 K.
Assertion: Zone refining method is very useful for producing semiconductors.
Reason: Semiconductors are of high purity.
Assertion: Hydrometallurgy involves dissolving the ore in a suitable reagent followed by precipitation by a more electropositive metal.
Reason: Copper is extracted by hydrometallurgy.
Explain the following:
Vapour phase refining method is used for the purification of Ti.
Purification of crude metals by removing metallic and non-metallic impurities is known as ______ of metals.
Which one of the following methods can be used to obtain highly pure metal which is liquid at room temperature?
Describe a method for refining nickel.
Describe a method for refining nickel.
Describe a method for refining nickel.
Describe a method for refining nickel.
Describe a method for refining nickel.
Describe a method for refining nickel.
Describe a method for refining nickel.
Describe a method for refining nickel.
Describe a method for refining nickel.
Describe a method for refining nickel.
