The results of the study "Mercury-Free Analysis of Total Iron in Lateritic and Iron Ores by Reductometric Titration with Ascorbic Acid" conducted by the Chemical Laboratory Service Section of the Metallurgical Technology Division of the Mines and Geosciences Bureau (MGB), proved that Ascorbic Acid titration is comparable with that of conventional volumetric titration with Potassium Dichromate (K2Cr2O7) using Mercury (II) Chloride. Thus, the Mercury-free analysis can be an alternative method in the determination of total iron, in iron bearing ores, minerals, mineral products and others.
Four nickel laterites, four iron ores and two Certified Reference Materials (CRM) were used in the study, with 10 tests conducted on each sample. The table below showed the comparative results of the two methods for nickel laterites / iron ore samples and the relative accuracy of the Mercury-Free method in reference with CRM.
The Mercury-free analytical method will be disseminated to the Mines and Geosciences Bureau (MGB) regional laboratories for validation. The adoption of such method will be discussed during a seminar-laboratory workshop scheduled in the last quarter of 2016 to be attended by MGB Central Office and Regional Office chemists.
Results of Total Iron (Fe) Analysis of Different Samples Analyzed Using Ascorbic
Acid Compared with Potassium Dichromate (K2Cr2O7) using Mercury (II) Chloride
|
Sample Mark |
Classification |
K2Cr2O7 Method 1 (accepted method ) |
Ascorbic Acid * Method 2 |
Certified Value |
Deviation (Method1- Method 2) |
% Relative** Accuracy |
|
15-32 #3 |
Laterite, submitted sample |
14.85 |
14.82 |
- |
- 0.03 |
99.80 |
|
15-33 #5 |
-do- |
16.25 |
16.24 |
- |
- 0.01 |
99.94 |
|
15-90 #1 |
-do- |
30.60 |
30.29 |
-0.31 |
98.99 |
|
|
15-90 #7 |
-do- |
44.05 |
43.96 |
- |
-0.09 |
99.80 |
|
15-38 #5 |
Iron Ore, submitted sample |
28.18 |
28.17 |
- |
- 0.01 |
99.96 |
|
15-38 #1 |
-do- |
36.56 |
36.54 |
- |
- 0.02 |
99.94 |
|
15-38 #8 |
-do- |
48.75 |
48.89 |
- |
+0.14 |
100.29 |
|
15-112 #1 |
-do- |
55.61 |
55.63 |
- |
+0.02 |
100.04 |
|
NIST 27C |
CRM, Iron Ore |
- |
65.02 |
65.00 |
- |
100.03 |
|
NIST 27F |
CRM, Iron ore |
- |
65.96 |
65.97 |
- |
99.98 |
*Average value of ten (10) tests conducted
** % Relative Accuracy (R.A.) = Method 2/Certified Value x 100 or % R.A. = Method 2/Method 1 x 100
By: Metallurgical Technology Division
Ms. Joycelyn F. Taal , Lead Researcher of the Project, at work.