Foreword

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This document was prepared by Technical Committee ISO/TC 27, Coal and coke, Subcommittee SC 1, Coal preparation: Terminology and performance.

This second edition cancels and replaces the first edition (ISO 8858-3:2004), which has been technically revised.

The main changes are as follows:

the title has been updated;
ISO 13909-2 , ISO 13909-4 and ISO 20904 were included as normative references.

A list of all parts in the ISO 8858 series can be found on the ISO website.

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.

Introduction

The froth flotation of coal has widespread application for the recovery of fine coal particles and their separation from unwanted mineral matter. The response of coal to the froth flotation process is measured initially by a laboratory scale test. ISO 8858-1 provides a means of evaluating the general flotation characteristics of a coal under a set of specified conditions and will not necessarily indicate the full potential of that coal. It is accepted that variation of the many parameters in the froth flotation process can be used to effect the beneficiation of the product. This document describes methods of applying certain test conditions to reveal the relative response of coals to the flotation process.

To facilitate the determination of how a particular coal will respond to froth flotation, a method of controlling the recovery of froth is used. This is done by inhibiting the process to a degree, determining the rate at which coal reacts and by progressively sampling the froth. This method provides a basis to vary test parameters to explore any special flotation characteristics.

This document is applicable to a wide range of coals and provides a method of comparison of flotation behaviour and will facilitate the exchange of information relating to specific performance. It is expected that the use of this method will provide a tool for comparison of flotation characteristics.

From the results of the standard test, it is possible to draw evaluation curves similar to those obtained from the float and sinking of coal.

Because of the high reproducibility of results, the test represents a reliable means of comparing the flotation response of different samples.

1 Scope

This document describes a laboratory method for release evaluation of the froth flotation characteristics of hard coal, of particle size less than 0,5 mm. It is applicable to coal in powder form or in the form of a slurry.

2 Normative references

3 Terms and definitions

4 Principle

5 Reagents

5.1

5.2

5.3

6 Apparatus

6.1

6.2

6.3

6.4

6.5

6.6

6.7

7 Sampling and preparation of test sample

8 Flotation test conditions

8.1 Test temperature

8.2 Impeller operating speed

8.3 Air flow rate

8.4 Pulp level

9 Procedure

9.1 Test portion

9.2 Preparation

9.3 Flotation test

10 Presentation of results

11 Test report

ISO 8858-3:2025

Coal. Froth flotation testing — - Part 3: Release evaluation

Current

Published:

12 Nov 2025

1 Scope