Abstract
Fuse 0.5g sample with fusion mixture (sodium carbonate 1: potassium carbonate 1). Leach it out with the warm water and add 3040 ml of 1 : 1 hydrochloric acid to dissolve manganese (IV). Add 23 drops of 3% hydogen peroxide and heat until it is boiled off.
Cool and dilute the solution to 250 ml. Take an aliquot (50 ml), add 20 ml 20% triethanolamine dilute to about 250ml, and make it alkaline with aq. NH3.
Then add 35 ml 25% ammonium fluoride and agitate the solution well for about 23 min. Add 20 ml 10% hydroxylamine-hydrochloride and adjust the pH to 1010.5 with aq. NH3. Add 23 drops of 5% potassium cyanide.
Titrate it with M/20 EDTA using thymolph-thalein complexone (TPC) as an indicator.
Manganese in usual manganese ores can be determined by this method without interference by iron, aluminum, calcium, magnesium and heavy metals. The method was superior in accuracy, precision and rapidity.
