This method is based on the titration of manganese ion with permanganate ion in neutral pyrophosphate solution, manganese(II) is oxidized, permanganate ion is reduced, turning into a pyrophosphate complex in the +3 state (stoichiometry ratio of Mn2 to MnO4 is 4:1).
The testing process includes the following steps:
All volumetric glassware must be Class A in accordance with ISO 648 and ISO 1042. Equipment used in testing, as well as ordinary laboratory apparatus, includes:
Sampling of manganese ores should be in accordance with ISO 4296-1 standard. Preparation of samples should be in accordance with ISO 4296-2 standard.
During the procedure, approximately 0,50 grams of the test sample is first weighed with a precision of 1 g. A blank test is then performed concurrently with the final stage. The hygroscopic moisture content is determined in accordance with the ISO 310 standard, simultaneously with the sampling of the test portion to determine the manganese content.
The test piece is placed in a 250 ml or 300 ml fluoroplastic or polytetrafluoroethylene beaker, moistened with a few drops of water, 10 ml of hydrochloric acid and 2 ml of nitric acid are added, the beaker is covered with a watch glass and heated until nitrogenous fumes cease to appear and cooled. 5 ml of perchloric acid is added and heated first gently, then strongly to decompose the ore. The solution is cooled, the watch glass is rinsed, the washings are transferred to the beaker. 5 ml of hydrofluoric acid is added and evaporated until dense white perchloric acid fumes appear. The solution is cooled, 10 ml of hydrochloric acid is added and heated until the salts dissolve. The insoluble residue is filtered through a medium-textured filter containing a small amount of paper pulp and washed 8 to 10 times with warm water. The filter volume should not exceed 120 ml. The filtrate is stored.
The filter paper containing the residue is placed in a platinum crucible, dried, the paper is charred at 600 degrees to 700 degrees, and finally melted with 900 g of sodium carbonate at 1000 degrees to 2 degrees. The crucible containing the melt is cooled, placed in a 250 ml beaker, 10 ml of hydrochloric acid and 30 ml to 40 ml of water are added, and heated to dissolve the melt. The crucible is removed and the beaker is washed with water. The solution is cooled and added to the filtrate.
The combined solution is transferred to a 250 ml volumetric flask, diluted to the mark with water and mixed. A 50,00 ml portion of the solution is taken and transferred to a 150 ml beaker containing 400 ml of saturated sodium pyrophosphate solution with constant stirring. The resulting solution should be clear. If a precipitate forms, it is necessary to take a small portion or more of saturated sodium pyrophosphate solution.
For titration, the pH value of the solution is adjusted to 7,0 with hydrochloric acid or sodium carbonate solution and titrated with potassium permanganate solution using the potentiometric titration apparatus until the maximum peak deflection is observed on the voltmeter.
Among the numerous testing, measurement, analysis and evaluation studies that our organization has carried out for businesses in various sectors, it also provides testing services defined in the “ISO 4298 Manganese ores and concentrates - Determination of manganese content - Potentiometric method” standard with its trained and expert staff and advanced technological equipment.
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