Transactions of the INDIAN CERAMIC SOCIETY Vol. 39 1980
Stepwise Complexometric Determination of
Calcium and Magnesium, and Manganese
1n Blast Furnace Slags and
Manganese Minerals
S. DASGUPTA AND B. C. SINHA
Pages : 94-97
DOI : 10.1080/0371750X.1980.10840729
Abstract
A simple and rapid complexometric method for stepwise
titration of Ca and Mg, and Mn in blast furnace slags and
manganese minerals has been worked out without involving
any separation of manganese. The method is based on the
joint titration of Ca and Mg at pH 10 using naptholgreenorthocresolphthalein-
ammonium chloride mixed indicator
after masking manganese effectively with KCN and bubbling
air through the solution (30° -40°C) for 10 minutes.
Manganese is then titrated at the same pH in the presence
of indicator solution containing eriochrome black T, titan
yellow and triethanol amine after reducing the Mn (ill)
hexacyano complex to Mn (ll) cyanide complex with ascorbic
acid. Calcium is, however, determined from a separate
aliquot by direct titration with EDTA using calcein-thymolphthalein
indicator after masking Mn with TEA and K CN.
