Chromium content of Chromium ores and concentrates

 

The REX Ti-50 Automatic Potential Titrator allows quick and simple determinations of the chromium content of chromium ores by potentiometric titration.

1. Standard Reference

ISO 6331-1983 《Chromium ores and concentrates Determination of Chromium content Titrimetric method》

ISO/DIS 6331 《Chromium ores and concentrates Determination of chromium content Titrimetric method》

The method is applicable to products having a chromium content greater than 7 % (m/m). Should be read in conjunction with ISO 6629. Specifies principle, reagents, apparatus, procedure and expression of results.

 

2. The Principle

Decomposition of a test portion by fusing with sodium per-oxide. Leaching the melt with water, acidifying with sulfuric acid and removing the excess of hydrogen peroxide by boiling.

Oxidation of chromium(lll) ions to chromate with ammonium peroxodisulphate in the presence of silver nitrate as catalyst.

Titration of chromium(Vl) with ammonium iron(ll) sulfate, the end-point being obtained either visually, by adding an excess of ammonium iron(ll) sulfate and back-titrating with potassium permanganate, or directly by potentiometric titration.

3. Recommended Configuration

1. Ti-50 Automatic Potential Titrator 

• Range：(-2000.00~2000.00) mV
• mV Accuracy：±0.03% or ±0.2mV
• 1 extra burette driver can be installed (optional).
• Replaceable burette with high-accuracy (10 ml or 20 ml selectable).
• Support acid-base titration, non-aqueous aqueous phase titration, constant titration, REDOX titration, precipitation titration, complexation titration
• Support the following titration modes: DET (dynamic equivalence point titration), MET (monotone equivalence point titration), SET (Preset Endpoint Titration) and MAT (manual titration).
• Titration methods, curves and results are displayed in detail.
• Includes 213-01 platinum electrode and 232-01 reference electrode.

2. Auxiliary titration unit 20mL
3. Burette valve device 20mL (SC5.461.057)
4. Anti-diffusion capillary
5. Electrodes

• 213-01 Platinum electrode
• 232-01 Reference electrode（Saturated KCl）

Model	213-01
Name	Platinum electrode
Connector Type	BNC(Q9)
Sensor material	Glass
Dimensions	Φ12×120mm
Measuring unit material	Platinum
Working Temperature	5~50 ℃
Application	REDOX Titration

Model	232-01
Name	Reference electrode
Type of electrode	Saturated single-junction calomel electrode
Connector Type	U shape terminal
Fill Solution	Saturated KCl solution
junction material	ceramic
Sensor material	Glass
Dimensions	Φ12×120 mm
Working Temperature	5~55 ℃

4. Titration Setting

• REDOX titration
• Sample for total content of vanadium and chromium: DET (dynamic equivalence point titration)
• Sample for content of vanadium : MET (monotone equivalence point titration)
• Blank Sample for total content of vanadium and chromium: MET (monotone equivalence point titration)

 

5. Titration curve

 

 

The titration curve of the total content of vanadium and chromium

 

The titration curve of vanadium content