MIL --- DTL --- 150E
4.4.13.2 Buffer solution. Dissolve 60 g of ammonium chloride in about 200 mL of water.
Add 570 mL of concentrated ammonium hydroxide and dilute to 1 L with water.
4.4.13.3 Indicator solution. Dissolve 0.15 g of Eriochrome Black T and 0.50 g of borax
(Na2B4O7·10H2O) in 35 mL of methanol and warm to effect solution.
4.4.13.4 Standard disodium dihydrogen ethylenediaminetetraacetate (EDTA). Dissolve
8.00 g of disodium dihydrogen EDTA in 2 L of water. Pipet 10 mL of standard magnesium solu-
tion prepared as specified in 4.4.13.1 into a 250 mL Erlenmeyer flask. Add 25 mL of water, 10
mL of buffer solution as prepared in 4.4.13.2, and 3 or 4 drops of indicator solution prepared as
specified in 4.4.13.3. Titrate against a white background under an incandescent light with dis-
odium dihydrogen EDTA solution to a pure blue end point with no trace of pink. Calculate the
molarity of the disodium dihydrogen EDTA solution as follows:
Molarity of disodium dihydrogen EDTA = 0.4112
A
where: A= Milliliters of disodium dihydrogen EDTA used to titrate standard magnesium
solution.
4.4.13.5 Procedure. Weigh to the nearest mg approximately 1 g of the specimen. Transfer
to a 250 mL Erlenmeyer flask, dissolve in 10 mL of a 1 to 10 solution of hydrochloric acid, add
25 mL of water, 10 mL of buffer solution prepared as specified in 4.4.13.2, and 3 or 4 drops of
indicator solution prepared as specified in 4.4.13.3. Titrate as specified in 4.4.13.4 and calculate
the percent magnesium carbonate as follows:
Percent magnesium carbonate = 8.433AB
W
where: A = Milliliters of disodium dihydrogen EDTA solution used,
B = Molarity of disodium EDTA solution calculated in 4.4.13.4, and
W = Weight in grams of specimen.
4.4.14 Granulation.
4.4.14.1 Classes 1, 2, 3, 4, 5, and 7. Select sieves conforming to ASTM E 11, as applicable
(see table II). Weigh to the nearest 0.01 g and nest in order of fineness with the most coarse
sieve on top. Place the assembly on a bottom pan. Weigh to the nearest 0.01 g approximately
100 g of the specimen and place it on the first (most coarse) sieve. Break lumps due to moisture
by gently brushing with a brush. Cover the sieves and shake for 10 minutes by hand or for 5
minutes by means of a mechanical shaker geared to produce 300 ± 15 gyrations and 150 ± 10
taps of the striker per minute. Weigh the material retained on each sieve and calculate the per-
cent material passing through each sieve as required by table II.
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