ISO 8858-2:2024

International
Standard
ISO 8858-2
Second edition
Coal — Froth flotation testing —
2024-09
Part 2:
Sequential evaluation
Charbon — Essais de flottation —
Partie 2: Évaluation séquentielle
Reference number
ISO 8858-2:2024(en)
© ISO 2024
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Published in Switzerland
ii
ISO 8858-2:2024(en)
Contents  Page
Foreword .iv
Introduction .v
1  Scope . 1
2  Normative references . 1
3  Terms and definitions . 1
4  Principle . 1
5  Sample . 2
6  Apparatus . 2
7  Flotation conditions . 2
7.1 Collector dosage .2
7.2 Frother dosage .2
7.3 Solids content . .2
7.4 Air flow rate .2
7.5 Test temperature .3
8  Procedure . 3
8.1 Initial procedure .3
8.2 Initial separation .3
8.3 Subsequent separations.3
8.4 Analysis of concentrate and tailings .3
9  Calculation of results . 4
10  Test report . 4
Annex A (informative)  Worked example of calculation of results . 6
Annex B (informative)  Presentation of results .11
Bibliography .15

iii
ISO 8858-2:2024(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
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with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
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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 8858-2 2004), of which it constitutes a minor
revision. The changes are as follows:
— updated title;
— document updated according to current ISO drafting rules.
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.

iv
ISO 8858-2:2024(en)
Introduction
The froth flotation of coal has a 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 a procedure for the more complete
determination of the flotation characteristics of a coal, using the apparatus and basic procedures described
in ISO 8858-1. The purpose of this extended procedure is to provide information similar to that provided
by the sink/float curve, which is the basis for density separations. The data obtained are expressed as a
yield/ash curve. The information can be used to define the limitations on the cleaning of fine coal by froth
flotation.
The procedures specified in this document are of practical significance in the development and evaluation of
coal-preparation-plant flotation circuits, although engineering design aspects, such as flotation kinetics and
the selection of size and type of cell, are not addressed.
The flotation response curve (yield/ash) indicates the maximum possible yield at any specified ash content.
The general shape of the curve indicates the sensitivity of flotation performance to the nature of the coal
and to operating conditions.
The procedure may be modified to test and compare the performance of different frother and collector
types, the assessment of liberation by grinding, and the comparison of alternative feed size ranges. However,
results of such tests should clearly indicate any use of non-standard procedures.

v
International Standard ISO 8858-2:2024(en)
Coal — Froth flotation testing —
Part 2:
Sequential evaluation
1  Scope
This document sets out a laboratory sequential procedure for the froth flotation testing of fine coal, e.g.
coal having a particle size of less than 0,5 mm. The procedure provides a means of evaluating the flotation
characteristics for coal (expressed as a yield/ash relationship) that can be expected from the froth flotation
process.
This document does not apply to pulp samples that cannot be dewatered without the use of heat or chemical
additives. This document does not apply to procedures for the investigation of flotation kinetics.
The test is not intended to provide plant design data.
This document is intended to be read in conjunction with ISO 8858-1.
2  Normative references
The following referenced documents are indispensable for the application 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 589, Hard coal — Determination of total moisture
ISO 1171, Coal and coke  — Determination of ash
ISO 1213-1, Coal and coke — Vocabulary — Part 1: Terms relating to coal preparation
ISO 1953, Hard coal — Size analysis by sieving
ISO 8858-1, Hard coal — Froth flotation testing — Part 1: Laboratory procedure
3  Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1213-1 apply.
ISO and IEC maintain terminology 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
A sequence of laboratory flotation tests is carried out on a single coal sample, using a procedure based on
that described in ISO 8858-1. Variations on that procedure are made to generate a number of products, by
refloating concentrates and tailings a number of times. The masses and ash mass fractions of the various
products are used to construct a yield/ash curve showing the flotation response.

ISO 8858-2:2024(en)
5  Sample
The history and method of sampling and preparation of samples can affect the flotation characteristics of
the coal considerably. The history of the sample should be recorded, and care should be taken to ensure
that samples for comparison purposes are sampled and prepared in a similar manner and, where applicable,
in accordance with the sampling and preparation procedures specified in ISO 13909-2, ISO 13909-4 and
ISO 18283.
A size analysis of the sample shall be carried out in accordance with ISO 1953.
6  Apparatus
The apparatus shall be as specified in ISO 8858-1.
7  Flotation conditions
7.1  Collector dosage
To establish well-defined flotation response curves, it is necessary to extend the range of conditions specified
in ISO 8858-1. Different coals will require different conditions to display the attainable range of yields and
corresponding product ash levels. To obtain a preliminary guide to the appropriate flotation conditions for
this extended test, it is recommended that a sample of the coal be first tested according to the procedure
specified in ISO 8858-1.
NOTE It is suggested that the collector increments referred to in 8.3 be selected on the basis of the result of the
ISO 8858-1 test in Table 1.
Table 1
ISO 8858-1 yield
ISO 88
...