Overview
ISO 9681:1990 specifies a standardized flame atomic absorption spectrometric method for the determination of iron content in manganese ores and concentrates. The method is applicable for products with iron content ranging from 0.2% to 10% by mass (m/m). This standard complements ISO 4297 and covers all analytical steps including reagents, apparatus, sampling, procedures, and expression of results.
This technique ensures accurate and reliable measurement of iron content, which is critical for quality control and industrial processing of manganese ores. The method involves the preparation of test solutions via chemical decomposition and fusion, followed by measurement of absorbance at iron-specific wavelengths using atomic absorption spectrometry.
Key Topics
- Scope and Applicability: Iron content analysis in manganese ores/concentrates within 0.2 to 10% range.
- Analytical Principle: Use of flame atomic absorption spectrometry at 248.3 nm or 344.06 nm wavelengths.
- Sample Preparation:
- Method 1: Decomposition with hydrochloric, hydrofluoric, perchloric acids.
- Method 2: Acid decomposition, removal of silica by volatilization, fusion of residue.
- Reagents: High-purity metallic manganese, hydrofluoric acid, perchloric acid, hydrochloric acid, nitric acid, hydrogen peroxide, and fusion mixtures.
- Apparatus Requirements: Platinum crucibles, polytetrafluoroethylene beakers, atomic absorption spectrometer with an air-acetylene flame burner.
- Calibration and Measurement: Preparation of calibration standards, measuring absorbance and constructing calibration graphs.
- Result Expression: Iron content expressed as percentage by mass, with permissible tolerances for reliability.
- Sampling: Use of laboratory samples with particle size below 100 µm according to ISO 4296.
Applications
- Mining and Mineral Processing: Accurate iron determination in manganese ores and concentrates for process optimization and quality assurance.
- Metallurgical Industry: Monitoring iron content to control alloy composition and material properties.
- Quality Control Laboratories: Routine chemical analysis compliant with international standards for product certification.
- Research and Development: Reliable analytical method for studies involving manganese ore composition and beneficiation.
The method supports traceability and consistency, essential in global trade of manganese mineral resources and derivative products.
Related Standards
- ISO 4297:1978 – General instructions for chemical analysis of manganese ores and concentrates.
- ISO 4296-1:1984 and ISO 4296-2:1983 – Sampling methods for manganese ores related to increment sampling and sample preparation.
- ISO 310:1981 – Determination of hygroscopic moisture content in manganese ores.
- Other ISO standards may provide complementary guidelines for sampling, preparation, and moisture analysis.
Practical Value
ISO 9681:1990 provides a thorough methodological framework ensuring precision, accuracy, and reproducibility in the determination of iron content in manganese ores. This is vital for compliance with international trade requirements and environmental reporting.
By standardizing the process, laboratories can reduce variability due to sample preparation or instrument conditions. The detailed reagent specifications and apparatus parameters ensure consistency across different testing facilities worldwide.
Keywords: ISO 9681, manganese ores, iron content determination, flame atomic absorption spectrometry, chemical analysis, mining, manganese concentrates, trace metal analysis, spectrometric method, international standard.
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