ISO 975:2021

Brown coals and lignites - Determination of yield of benzene-soluble extract - Semi-automatic method

This document specifies a semi-automatic method for determination of the yield of benzene-soluble extract in brown coals and lignites.

Charbons bruns et lignites — Détermination du rendement en extrait de benzène soluble — Méthode semi-automatique

General Information

• Status: Published
• Publication Date: 06-Dec-2021
• ICS: 73.040 - Coals
• Technical Committee: ISO/TC 27/SC 5 - Methods of analysis
• Drafting Committee: ISO/TC 27/SC 5/WG 7 - Brown coals and lignites
• Current Stage: 6060 - International Standard published
• Start Date: 07-Dec-2021
• Due Date: 17-Oct-2022
• Completion Date: 07-Dec-2021

Relations

• Revises: ISO 975:2013 - Brown coals and lignites - Determination of yield of benzene-soluble extract - Semi-automatic method
• Effective Date: 23-Apr-2020

Overview

ISO 975:2021 specifies a semi-automatic method for determining the yield of benzene-soluble extract in brown coals and lignites. This standard outlines the use of a dedicated extraction instrument that combines extraction, rinsing, and evaporation processes to accurately quantify benzene-soluble extracts. This procedure is vital for assessing the quality and chemical characteristics of brown coal and lignite samples in both research and industrial settings.

Key Topics

• Scope and Application
  The method applies specifically to brown coals and lignites, focusing on the yield of benzene-soluble extracts reported on a dry basis after moisture correction.

• Semi-Automatic Extraction Instrument
  The standard describes the apparatus consisting of an extraction chamber with a water jacket, conical flask, condenser, and controller. This automation allows standardized and reproducible testing conditions by controlling temperature and timing during extraction.

• Test Procedure
  The sample (2 g) is placed in an extraction thimble, benzene solvent added, and the instrument undergoes extraction (180 min), rinsing (10 min), and evaporation (50 min) steps automatically. The extracted solvent residue is dried to constant mass to determine the benzene-soluble yield.

• Reagent and Safety
  High-purity benzene (analytical reagent grade) is used as a solvent. The standard emphasizes strict safety measures due to benzene’s toxicity and flammability, recommending usage in a fume hood and complete recovery of benzene.

• Calculation of Results
  The benzene-soluble extract percentage is calculated based on the mass of dried residue relative to the test sample, with results expressed on a dry basis after moisture adjustment according to ISO 5068-2.

• Precision and Repeatability
  ISO 975:2021 defines limits for repeatability and reproducibility. Duplicate tests in the same lab should have differences within 0.3% to 0.5%, while inter-laboratory reproducibility limits vary between 0.5% and 0.7% depending on extract yield.

• Documentation and Reporting
  Test reports must include sample identification, reference to ISO 975:2021, test dates, and detailed results with expressions used for clarity.

Applications

• Coal Quality Assessment
  The determination of benzene-soluble extracts is crucial in evaluating brown coals and lignites’ chemical composition. This parameter helps identify the presence of volatile organic compounds and extractables impacting coal utilization processes.

• Industrial Process Optimization
  Measuring benzene-soluble yields assists industries such as power generation, gasification, and coal processing in optimizing feedstock selection and processing parameters.

• Research and Development
  Laboratories engaged in coal chemistry research utilize this standardized method for consistent data generation and comparison across studies focusing on brown coal and lignite properties.

• Environmental Monitoring
  Understanding extractable organic matter assists in assessing environmental impact and emission characteristics related to coal combustion.

Related Standards

• ISO 5068-2 – Brown coals and lignites - Determination of moisture content by indirect gravimetric method on the analysis sample. Essential for correcting moisture content in yield calculations.

• ISO 13909-4 – Hard coal and coke - Mechanical sampling - Preparation of test samples, ensuring representative sampling prior to extract determination.

• ISO 18283 – Coal and coke - Manual sampling, providing guidelines for sample collection critical to test accuracy.

• ISO/IEC Directives – Editorial and procedural guidelines for ISO standards maintenance and revision, ensuring consistent document quality and updates.

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By adhering to ISO 975:2021, laboratories and industries can ensure precise, reproducible, and standardized measurement of benzene-soluble extracts in brown coals and lignites, enhancing data quality in coal analysis and contributing to improved processing and environmental compliance.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 975
Fifth edition
2021-12
Brown coals and lignites —
Determination of yield of benzene-
soluble extract — Semi-automatic
method
Charbons bruns et lignites — Détermination du rendement en extrait
de benzène soluble — Méthode semi-automatique
Reference number
© ISO 2021
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagent . 1
6 Apparatus . 1
7 Preparation of sample . 2
8 Preliminary adjustment of instrument . 2
8.1 Adjustment of the extraction temperature . 2
8.2 Selection of periods of extraction, rinsing and evaporation . 2
8.3 Procedure . 3
9 Calculation and expression of results . 3
10 Precision . 4
10.1 Repeatability limit . 4
10.2 Reproducibility limit . 4
11 Test report . 4
iii
Foreword
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 27, Coal and coke, Subcommittee SC 5,
Methods of analysis.
This fifth edition cancels and replaces the fourth edition (ISO 975:2013), of which it constitutes a minor
revision. The changes compared to the previous edition are as follows:
— referenced documents have been updated;
— terms and definitions have been added;
— sample has been added;
— calculation and expression of results have been amended;
— precision has been amended;
— test report has been amended.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html
iv
Introduction
The determination of yield of benzene-soluble extract is carried out using a semi-automatic instrument;
a system combining extraction, rinsing and evaporation. As long as the sample is put in the extraction
chamber of the instrument, the test can be done automatically.
v
INTERNATIONAL STANDARD ISO 975:2021(E)
Brown coals and lignites — Determination of yield of
benzene-soluble extract — Semi-automatic method
1 Scope
This document specifies a semi-automatic method for determination of the yield of benzene-soluble
extract in brown coals and lignites.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 5068-2, Brown coals and lignites — Determination of moisture content — Part 2: Indirect gravimetric
method for moisture in the analysis sample
ISO 13909-4, Hard coal and coke — Mechanical sampling — Part 4: Coal — Preparation of test samples
ISO 18283, Coal and coke — Manual sampling
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Principle
...