4a (65)

g) If the quicklime and water mixture is agitated during hydration the ratę is increased.

Depending on ratę of slaking there are three kinds of limę:

I    - time of slaking to 15 min

II    - time of slaking 15 - 30 min

III    - time of slaking above 30 min

REALIZATION OF PRACTICE

1.    Determination of available CaO and MgO

Determination should be done using the method given in PN - 76/B - 04350. On the base of result determine sort of limę (table 1)

2.    Determination time and temperaturę of slaking

Determination should be done using the method given in PN - 77/B - 04351. Determine:

-    temperaturę of slaking - the highest temperaturę during slaking [°C],

-    time of slaking [min] - time, when the highest temperaturę has been reached,

-    time when 60°C has been reached,

-    sort of limę

-    draw wet slaking curve.

Ad.1 Determination of availabble limę content of air limes

1.1 .Principles

The available (unbond) calcium oxide and magnesium oxide is dissolved in a solution of water and titrated with hydrochloric acid; phenolphthalein being used as an indicator.

1.2.    Reagents

a)    hydrochloric acid (1mol/l) standard solution,

b)    phenolphthalein indicator - dissolve 0,5g of phenolphthalein in 50 ml of ethanol and dilute to 100ml with water

1.3.    Procedurę

Place 1g of limę in a 300ml conical fiask, add 200ml fresh boiled water, cover with watch glass and boil for 5 - 10 min. After cooling, add 2-3 drops of phenolphthalein and titrate the solution with the hydrochloric acid. Titrating is ended when after 5 min doesn’t occur pink colour of the solution.

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