ASTM E246 Standard Test Methods for Determination of Iron in Iron Ores and Related Materials by Dichromate Titrimetry

Get Certified ASTM E246 Testing for Reliable Iron Ore Value Determination 

In international trade, total iron content directly affects an ore’s value, and accurate analysis is critical for both buyers and sellers; therefore, reliable dichromate titrimetric analysis is necessary. ASTM E246-certified laboratories perform testing in accordance with ASTM referee practices to measure the “total iron” content of ores, concentrates, and agglomerates. Accredited laboratory testing supports ore grade assessment, compliance with pellet specifications, and raw material quality control in a steel plant. Trained analysts provide reliable iron-content results by using ASTM E246 in properly equipped laboratories and following the quality control procedures in Guide E882. 

• Material type: Iron ores, concentrates and agglomerates (sinter, pellets, direct reduced iron products, hematite, magnetite, goethite ores). 
• Purpose: Referee-grade determination of total iron content for commercial valuation and process control. 
• Properties evaluated: Total iron content (Fe) % by weight. 
• Testing Method: Dichromate titrimetry, after hydrogen sulfide, stannous chloride or silver reduction, as chosen. 
• Result: Total iron content reported as % iron in the range 30% to 95% iron. 
• Test Limitations: Test Method A is recommended for use on material with a Fe content between 30% and 75%, and Test Methods B and C for a Fe content between 35% and 95%.
• Units: Values are given and reported in SI units. 
• Applications: Determination of iron ore grade for commercial trading, quality control in blast furnace burden preparation, analysis of pelletizing plant feed and product, and direct-reduced iron product certification. 

What are the Uses of ASTM E246 Testing?

ASTM E246 testing provides a well-established referee test for the total iron content of ores and related materials. The buyer, seller, and steel producers then use the results to determine the commercial value and make process decisions.  This standard-

• Accurately measures iron in a broad range of concentrations, from 30% to 95% Fe.
• Is the major indicator to determine the international trade value of the iron ore.
• Provides three different methods of dichromate titration for various ranges of iron concentration.
• Ensures continuous raw material analysis to support process control in blast furnace and direct reduction processes.
• Helps meet commercial trading requirements on ore grade.
• Helps to monitor quality control in pelletizing plants and direct-reduced iron production plants. 

What Materials Can Be Tested Under ASTM E246? 

ASTM E246 applies to iron ores or concentrates and iron ore agglomerates such as hematite ores, magnetite ores, goethite ores, concentrates, sinter, pellets, and direct reduced iron or hot briquetted iron. The test methods cover concentrations from 30% to 95%, depending on whether the analyst selects Method A, B, or C. An analyst first checks the anticipated amount of iron in the sample to ensure that the appropriate test method and reduction are used before starting analysis.

Why is ASTM E246 Important? 

The reference methods outlined in ASTM E246 provide standard procedures for determining total iron content, which is the primary way to determine the commercial value of iron ore in international trade. Precise iron measurement also plays an important role in the ironmaking process, such as blast furnace and direct reduction steelmaking processes, where the quality of raw materials directly influences the efficiency and consistency of production. These test methods are often used as referee methods and are used to settle compositional differences between trading parties. Steel producers, ore traders, and pelletizing plants use this standard to validate the grade of the ore, to ensure the commercial specification of the ore, and to ensure consistent raw material quality within the ore supply chain. 

ASTM E246 Testing Process and Data Collection

The analyst takes a representative sample of the ore, concentrate, or agglomerate and selects the test method based on the sample’s iron content.  After this, the technicians dissolve the sample in hydrochloric acid, filter out any insoluble material, and burn it to recover the iron content, which is added back to the main solution. The analyst uses the reducing agent specified in the selected method to convert ferric iron to ferrous iron and oxidizes any excess reductant. The resulting solution is then titrated with a standard potassium dichromate solution, with the sodium diphenylamine sulfonate indicator changing color at the endpoint or with the use of a potentiometric endpoint. Finally, the analyst uses the amount of dichromate required to determine the total iron content as a percentage.

Common Challenges and Troubleshooting

To obtain accurate ASTM E246 results, the analyst must completely dissolve the sample, reduce the ferric iron, and remove the excess reducing agent before titration.  If the sample of ore is not completely dissolved and is not properly filtered, ignited, and recovered, the iron may not all be accounted for in the insoluble residue. Excess reductant that is not completely oxidized prior to titration may cause errors in the amount of dichromate consumed and erroneous results to be obtained. Some ores contain interfering constituents which can alter the indicator endpoint or give rise to side reactions in the process of titration. These problems are minimised through proper reagent standardization, complete recovery of the residue, and careful oxidation of the excess reductant. 

• The laboratory reports total iron content as a percent of the sample, in the range for the iron test method applied.
• The analyst uses the appropriate test method, A, B, or C, based on the concentration of iron that is expected in the sample, and records that choice.
• The laboratory records the reducing agent and conditions used in the analysis. The results are the main criteria for determining the commercial value of the ore tested in trading.
• The laboratory supplies total iron results for process control for blast furnace and direct reduction processes.
• Engineers obtain consistent, referee-grade results through standard dissolution, reduction, and titration procedures. The total iron content data is used to ensure compliance with commercial trading specifications and raw material quality control. 

Link to ASTM E246