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Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

In the leaching of gold by cyanide process, the following reaction takes place: 
$\displaystyle aAu+bKCN+cH _{2}O+dO _{2}\rightarrow eKAu(CN) _{2}+fKOH$
$\displaystyle uAu+vKCN+wH _{2}O+xO _{2}\rightarrow yKAu(CN) _{4}+zKOH$
Identify the correct statements with respect to the stoichiometric coefficients when these reactions are balanced using simplest natural numbers.

  1. $d, c, x, u$ are in anthmetic progression
  2. $c, y, w, b$ are in arithmetic progression
  3. $f, b, z, v$ are in geometic progressinon
  4. $d, c,a, b$ are geometnic progression
Reveal answer Fill a bubble to check yourself
A,B,D Correct answer
Explanation

$\displaystyle 4Au+8KCN+2H _{2}O+O _{2}\rightarrow 4KAu(CN) _{2}+4KOH$
$\displaystyle 4Au+16KCN+6H _{2}O+3O _{2}\rightarrow 4KAu(CN) _{4}+12KOH$
$a = 4$      $ b = 8$       $c = 2$      $ d = 1$        $e = 4$               $f = 4$
$u = 4$     $ v = 16$       $ w = 6$       $ x = 3$     $ y = 4$           $ z = 12$ 

Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

The principle behind froth floatation is:

  1. preferential wetting of ore and gangue particles.

  2. difference is specific gravity of ore and gangue particles.

  3. magnetic properties of ore and gangue.

  4. electrical properties of gangue particles.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Froth flotation commences by comminution (that is, crushing and grinding), which is used to increase the surface area of the ore for subsequent processing and break the rocks into the desired mineral and gangue in a process known as liberation, which then has to be separated from the desired mineral. The ore is ground into a fine powder and mixed with water to form a slurry. The desired mineral is rendered hydrophobic by the addition of a surfactant or collector chemical. The particular chemical depends on which mineral is being refined. As an example, pine oil is used to extract copper. This slurry (more properly called the pulp) of hydrophobic mineral-bearing ore and hydrophilic gangue is then introduced to a water bath which is aerated, creating bubbles. The hydrophobic grains of mineral-bearing ore escape the water by attaching to the air bubbles, which rise to the surface, forming a foam or a scum (more properly called a froth). The froth is removed and the concentrated mineral is further refined.

Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

Iron ores are concentrated by:

  1. froth floatation method

  2. magnetic separation method

  3. amalgamation method

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Iron ores are concentrated by magnetic separation method.
In  magnetic separation method, ferromagnetic and nonmagnetic particles in the ore are separated by an electromagnetic separator.

Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

Chemical method used in concentration of ore is known as ___________.

  1. bleaching

  2. leaching

  3. roasting

  4. calcination
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Leaching is a chemical method of concentration of ores. It involves the treatment of the ore with a suitable reagent so as to make it soluble while impurities remain insoluble. The ore is recovered from the solution by suitable chemical method. Copper is recovered from chemical solutions by leaching processes such as solvent extraction.

Multiple choice chemistry principles of metallurgy concentration of ore concentration of ores general principles of metallurgy

In Bayer's process, the crushed ore is treated with ______ .

  1. hot concentrated caustic soda (NaOH)

  2. cold dilute caustic soda (NaOH)

  3. hot concentrated caustic potash (KOH)

  4. cold dilute caustic potash (KOH)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Bayer's process is the industrial refining process to refine bauxite to produce alumina. In this process, the crushed ore is treated with hot concentrated caustic soda (NaOH).

Multiple choice chemistry principles and processes of isolation of elements concentration of ore concentration of ores principles of metallurgy

Baking powder has one of the following constituents, which is:

  1. $Na _{2}CO _{3}$
  2. $Na _{2}SO _{4}$
  3. $KHCO _{3}$
  4. $NaHCO _{3}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sodium bicarbonate, also called sodium hydrogen carbonate, or bicarbonate of soda, $NaHCO _3$, is a source of carbon dioxide and so is used as an ingredient in baking powders, in effervescent salts and beverages, and as the main constituent of dry-chemical fire extinguishers. Its slight alkalinity.