ASTM D5114/D5114M-90(2018)e1

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Designation: D5114/D5114M − 90 (Reapproved 2018)
Standard Test Method for
Laboratory Froth Flotation of Coal in a Mechanical Cell
This standard is issued under the fixed designation D5114/D5114M; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last
reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—The designation was editorially updated to dual and other editorial changes were made throughout in March
2019.
INTRODUCTION
Froth flotation of coal, the separation of ash-bearing minerals from combustibles via differences in
surface chemistry, has been steadily increasing in use as a means to treat 600 µm (No. 30 U.S.A.
Standard Sieve Series) or finer coal.The process is one in which many variables need to be monitored
and regulated. Because of this complexity, rigorous laboratory testing is difficult to standardize.
This test method outlines the types of equipment and procedures to apply on a laboratory scale to
isolate key process variables and minimize the variations associated with the design and execution of
a froth flotation test. The objective of the test method is to develop a means by which repeatable
grade/recovery results are ascertained from froth flotation testing of coal without imposing
unnecessary limitations on the applicability of the test results in coal preparation practice.
It is recognized that sample preparation, particularly comminution, has a significant impact on froth
flotation response. This test method does not attempt to define sample preparation and size reduction
practices as part of a froth flotation testing program.
Thistestmethodalsodoesnotcompletelycoverspecificproceduresfortheinvestigationofflotation
kinetics. Such a test is specialized and is highly dependent upon the end use of the data.
1. Scope 1.4 Laboratoryflotationresultsneednotberepresentativeof
the flotation response of coal in full-scale situations, but a
1.1 This test method covers a laboratory procedure for
consistent baseline can be established against which full-scale
conducting a single froth flotation test on fine coal (that is,
performance can be compared.
nominal top size of 600 µm (No. 30 U.S.A. Standard Sieve
Series) or finer) using a defined set of starting point conditions
1.5 The values stated in either SI units or inch-pound units
for the operating variables. are to be regarded separately as standard. The values stated in
each system are not necessarily exact equivalents; therefore, to
1.2 This test method does not completely cover specific
ensure conformance with the standard, each system shall be
procedures for the investigation of flotation kinetics. Such a
used independently of the other, and values from the two
test is specialized and highly dependent upon the objective of
systems shall not be combined.
the data.
1.6 Material Safety Data Sheets (MSDS) for reagents used
1.3 Since optimum conditions for flotation are usually not
are to be obtained from suppliers who are to be consulted
found at the specified starting points, suggestions for develop-
before work with any chemicals used in this test method.
ment of grade/recovery curves are given inAppendix X1. Such
a procedure is very case-specific and involves running a series
1.7 This standard does not purport to address all of the
of flotation tests in which some of the operating variables are safety concerns, if any, associated with its use. It is the
changed in order to optimize conditions for either yield or
responsibility of the user of this standard to establish appro-
grade. priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.8 This international standard was developed in accor-
dance with internationally recognized principles on standard-
This test method is under the jurisdiction of ASTM Committee D05 on Coal
and Coke and is the direct responsibility of Subcommittee D05.07 on Physical
ization established in the Decision on Principles for the
Characteristics of Coal.
Development of International Standards, Guides and Recom-
Current edition approved Nov. 1, 2018. Published March 2019. Originally
mendations issued by the World Trade Organization Technical
approved in 1990. Last previous edition approved in 2010 as D5114 – 90(2010).
DOI: 10.1520/D5114_D5114M-90R18E01. Barriers to Trade (TBT) Committee.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D5114/D5114M − 90 (2018)
2. Referenced Documents 3.2.11 natural pH—the measured pH of the pulp prior to the
2 addition of collector, frother, or any conditioning agents.
2.1 ASTM Standards:
3.2.12 pulp—afluidmixtureofsolidsandwater,alsoknown
D121 Terminology of Coal and Coke
as slurry.
D2013 Practice for Preparing Coal Samples for Analysis
D3174 Test Method for Ash in the Analysis Sample of Coal
3.2.13 recovery—the percent of the valuable component
and Coke from Coal
(that is, Btu or combustible) from the feed that reports to the
D4749 Test Method for Performing the Sieve Analysis of
froth concentrate product.
Coal and Designating Coal Size
3.2.14 solids concentration—the ratio, expressed as a
percent, of the weight (mass) of solids to the sum of the weight
3. Terminology
of solids plus water.
3.1 Definitions—For definitions of terms used in this test
3.2.15 tailings—the underflow product from coal froth flo-
method, see Terminology D121.
tation.
3.2 Definitions of Terms Specific to This Standard:
3.2.16 yield—the weight percent of the feed that reports to
3.2.1 collector—a reagent used in froth flotation to promote
the concentrate.
contact and adhesion between particles and air bubbles.
4. Significance and Use
3.2.2 combustibles—the value obtained by subtracting the
dry weight (in percent) of the ash (as determined in Test
4.1 This test method uses specific starting point conditions
Method D3174) from 100 % representing the original weight
for the froth flotation response to accomplish the following:
of the analyzed sample.
4.1.1 Assess responses of one or more coals or blends of
coal, and
3.2.3 concentrate—the froth product recovered in coal froth
flotation. 4.1.2 Evaluate and determine froth flotation circuit perfor-
mance.
3.2.4 conditioning agents—all chemicals that enhance the
performance of the collectors or frothers. Conditioning agents
5. Apparatus
change the characteristics of the surface of the minerals or the
5.1 Laboratory Flotation Machine,withaminimumvolume
environment.There are many subgroups according to function:
of 2 L and a maximum volume of 6 L. Fig. 1 schematically
activators, depressants, emulsifiers, dispersants, flocculants,
depicts a batch mechanical flotation cell which can be used in
chelating reagents, froth depressants, pH modifiers, and so
conjunction with this test method. The major criterion is that
forth.
the unit must be able to provide for constant mechanical
3.2.5 flotation cell—the vessel or compartment in which the
removal of froth from the cell. In addition, the laboratory unit
flotation test is performed.
must have some means of automatic liquid level control.
3.2.6 froth—a collection of bubbles and particles on the
5.1.1 An example of a mechanical paddle laboratory froth
surface of a pulp in a froth flotation cell.
flotation apparatus is shown in Fig. 1. The froth paddles are
3.2.7 froth flotation—a process for cleaning fine coal in
which hydrophobic particles, generally coal, attach to air
bubbles in a water medium and rise to the surface to form a
froth. The hydrophilic particles, generally the ash-forming
matter, remain in the water phase.
3.2.8 frother—a reagent used in froth flotation to control the
size and stability of the air bubbles, principally by reducing the
surface tension of water.
3.2.9 grade/recovery—the relationship between quality and
quantity of the clean coal product. The quality can be defined
in terms of ash, sulfur, or Btu content. The quantity can be
designated as yield or heating value recovery (Btu or combus-
tibles).
3.2.10 mechanical cell—atypeofflotationcellthatemploys
mechanical agitation of a pulp by means of an immersed
impeller (rotor) and stator stirring mechanism. Aeration to the
cell can be from an external pressurized air source or self-
induced air.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. FIG. 1 5.5 L Mechanical Paddle Laboratory Froth Flotation Cell
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D5114/D5114M − 90 (2018)
rotated at approximately 30 r/min, thus avoiding variation 7.3 Water—Plant, tap, or distilled water may be used,
caused by manual removal of froth. The froth paddle shall not whichever is consistent with the object of the test. The source
rotate below the pulp surface and not more than 6 mm [ ⁄4 in.] of water must be recorded.
abovethepulplevel.Thedistancebetweentheoverflowlipand
7.4 Solids Content—The solids content corresponds with
the edge of the froth paddle shall be at least 3 mm [ ⁄8 in.] but
thatoftheindustrialpreparationplantslurry,iftheobjectofthe
not more than 6 mm [ ⁄4 in.].
test is to simulate plant conditions. Otherwise, an 8 % solids
5.1.2 Thepulpinthecellismaintainedataconstantlevelby
concentration shall be used.
a small tank with an overflow at precisely the desired level to
7.5 Pulp Level—Maintain between 12.7 mm and 15.9 mm
be maintained in the flotation cell.
[0.50 in. and 0.62 in.] below the lip of the cell as measured
NOTE 1—Another suitable slurry level control system consists of a with the air on and stirrer operating.
resistance type level probe, a resistance sensor relay, a solenoid valve, and
7.6 Wetting of Coal—Before the addition of reagents and
associated connecting wires. The level probe is mounted inside the cell
subsequentflotation,itisimportanttoensurethattheproperair
and is connected to the resistance relay which operates the solenoid valve.
When the slurry level drops below the tip of the probe, the relay energizes bubble attachment can take place at the coal-water interface.
thesolenoidvalve.Then,makeupwaterflowsintothecell.Whenthelevel
Wetting is accomplished in the cell by running the impeller at
rises up to the probe, the solenoid valve is de-energized, which stops the
the r/min specified for the flotation step with the air off.
makeup water flow.
Perform this step for 5 min to 10 min before reagent addition.
5.2 pH Meter, sensitive to 0.1 units.
Ifthesampleisinslurryformthiswettingstepisnotnecessary.
5.3 Timing Device that displays cumulative minutes and 7.7 Reagent Addition—Collector, frother, conditioning
seconds. agent, or any combination thereof shall be governed by the
requirements of the test. Add reagents to the coal slurry and
5.4 Air Flow Meter.
conditiontoensureproperdistributionofreagents.Conductthe
5.5 Microsyringes or Pipets. conditioning step at the same impeller speed as the flotation
step with the air flow off.
5.6 Balances, with a readability of at least 0.5 % of the total
7.7.1 Add the reagents using either a calibrated microsy-
weight.
ringe or a pipet.
5.7 Vacuum or Pressure Filter, or a filter funnel for gravity
7.8 Air Flow—Rate shall be measured and recorded.
filtration.
7.9 Impeller Speed—The starting speed shall be 1200 r/min.
5.8 Drying Oven with forced air, capable of maintaining a
NOTE 2—Impeller speed is an important variable and should be
maximum temperature of 40 °C [104 °F] and meeting the
investigated during optimization, depending on the object of the test.
requirements of Practice D2013.
5.9 Rinse Bottle.
TABLE 1 Starting Point Conditions for Laboratory Froth Flotation
of Coal
6. Sample Preparation
NOTE 1—Additional time can be required for a slowly responsive coal;
record any extra time.
6.1 The sample history, moisture content, alteration of the
Solids concentration 8 % solids
inherent moisture, or alteration of the surface properties have
Total volume 2 L to 6 L
considerableeffectontheflotationcharacteristicsofthecoal.It
Wetting time 5 min
pH natural
is important that all samples used in flotation testing are stored
Impeller speed 1200 r/min
and handled so as to minimize alteration of the surface
Reagent additions and conditioning times:
properties. The origin and history of the sample should be
1. Add collector
2. Condition for 90 s
recorded. It is imperative that all samples be prepared in a
3. Add frother
similar manner. Since the generation of grade/recovery curves
4. Condition for 30 s
will involve several individual tests, sample subdivision and
Air flow rate 3 L/min per litre of pulp
Skimmer rotation 30 r/min
preparation must be carefully performed to ensure that each
Collection increments 15, 30, 60, 90, 120, 240 (cumulative time
subsample is rep
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