ASTM D5114-90(2004)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:D5114–90(Reapproved 2004)
Standard Test Method for
Laboratory Froth Flotation of Coal in a Mechanical Cell
This standard is issued under the fixed designation D5114; 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.
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 consistent baseline can be established against which full-scale
performance can be compared.
1.1 This test method covers a laboratory procedure for
1.5 The values stated in SI units are to be regarded as
conducting a single froth flotation test on fine coal (that is,
standard. The values in parentheses are provided for informa-
nominal top size of 600 µm (No. 30 U.S.A. Standard Sieve
tion only. The values stated in each system may not be exact
Series) or finer) using a defined set of starting point conditions
equivalents; therefore, each system must be used indepen-
for the operating variables.
dently of the other, without combining values in any way.
1.2 This test method does not completely cover specific
1.6 This standard does not purport to address the safety
procedures for the investigation of flotation kinetics. Such a
concerns, if any, associated with its use. It is the responsibility
test is specialized and highly dependent upon the objective of
of the user of this standard to establish appropriate safety and
the data.
health practices and determine the applicability of regulatory
1.3 Since optimum conditions for flotation are usually not
limitations prior to use.
found at the specified starting points, suggestions for develop-
1.7 Material Safety Data Sheets (MSDS) for reagents used
ment of grade/recovery curves are given inAppendix X1. Such
are to be obtained from suppliers who are to be consulted
a procedure is very case-specific and involves running a series
before work with any chemicals used in this test method.
of flotation tests in which some of the operating variables are
changed in order to optimize conditions for either yield or
2. Referenced Documents
grade.
2.1 ASTM Standards:
1.4 Laboratoryflotationresultsneednotberepresentativeof
D121 Terminology of Coal and Coke
the flotation response of coal in full-scale situations, but a
D2013 Practice for Preparing Coal Samples for Analysis
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
Characteristics of Coal. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved April 1, 2004. Published May 2004. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1990. Last previous edition approved in 1998 as D5114 – 90 (1998).
Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D5114-90R04.
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D5114–90 (2004)
D2015 Test Method for Gross Calorific Value of Coal and 3.2.10 mechanical cell—a type of flotation cell that em-
Coke by the Adiabatic Bomb Calorimeter ploys mechanical agitation of a pulp by means of an immersed
impeller (rotor) and stator stirring mechanism. Aeration to the
D2234/D2234M Practice for Collection of a Gross Sample
cell can be from an external pressurized air source or self-
of Coal
induced air.
D3173 Test Method for Moisture in theAnalysis Sample of
3.2.11 natural pH—themeasuredpHofthepulppriortothe
Coal and Coke
addition of collector, frother, or any conditioning agents.
D3174 Test Method forAsh in theAnalysis Sample of Coal
3.2.12 pulp—a fluid mixture of solids and water, also
and Coke from Coal
known as slurry.
D3177 Test Methods for Total Sulfur in the Analysis
3.2.13 recovery—the percent of the valuable component
Sample of Coal and Coke
(that is, Btu or combustible) from the feed that reports to the
D4239 Test Method for Sulfur in the Analysis Sample of
froth concentrate product.
Coal and Coke Using High-Temperature Tube Furnace
3.2.14 solids concentration—the ratio, expressed as a per-
Combustion
cent, of the weight (mass) of solids to the sum of the weight of
D4749 Test Method for Performing the Sieve Analysis of
solids plus water.
Coal and Designating Coal Size
3.2.15 tailings—the underflow product from coal froth flo-
tation.
3. Terminology
3.2.16 yield—the weight percent of the feed that reports to
the concentrate.
3.1 Definitions—For definitions of terms used in this test
method, see Terminology D121.
4. Significance and Use
3.2 Definitions of Terms Specific to This Standard:
4.1 This test method uses specific starting point conditions
3.2.1 collector—a reagent used in froth flotation to promote
for the froth flotation response to accomplish the following:
contact and adhesion between particles and air bubbles.
4.1.1 Assess responses of one or more coals or blends of
3.2.2 combustibles—the value obtained by subtracting the
coal, and
dry weight (in percent) of the ash (as determined in Test
4.1.2 Evaluate and determine froth flotation circuit perfor-
Method D3174) from 100 % representing the original weight
mance.
of the analyzed sample.
3.2.3 concentrate—the froth product recovered in coal froth
5. Apparatus
flotation.
5.1 Laboratory Flotation Machine,withaminimumvolume
3.2.4 conditioning agents—all chemicals that enhance the
of 2 L and a maximum volume of 6 L. Fig. 1 schematically
performance of the collectors or frothers. Conditioning agents
depicts a batch mechanical flotation cell which can be used in
change the characteristics of the surface of the minerals or the
environment.There are many subgroups according to function:
activators, depressants, emulsifiers, dispersants, flocculants, A suitable cell, available from WEMCO, 1796 Tribute Rd., Sacramento, CA
95815, or equivalent can be used.
chelating reagents, froth depressants, pH modifiers, and so
forth.
3.2.5 flotation cell—the vessel or compartment in which the
flotation test is performed.
3.2.6 froth—a collection of bubbles and particles on the
surface of a pulp in a froth flotation cell.
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—areagentusedinfrothflotationtocontrolthe
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).
Withdrawn. The last approved version of this historical standard is referenced
on www.astm.org. FIG. 1 5.5-L Mechanical Paddle Laboratory Froth Flotation Cell
D5114–90 (2004)
conjunction with this test method. The major criterion is that are for laboratory testing parameters and are not designed to
the unit must be able to provide for constant mechanical simulate in-plant operating conditions that can be highly
removal of froth from the cell. In addition, the laboratory unit variable, such as water temperature and chemistry.
must have some means of automatic liquid level control. 7.2 Slurry Temperature—The operating temperature shall
5.1.1 An example of a mechanical paddle laboratory froth be 22 6 5°C (72 6 9°F).
flotation apparatus is shown in Fig. 1. The froth paddles are 7.3 Water—Plant, tap, or distilled water may be used,
rotated at approximately 30 r/min, thus avoiding variation whichever is consistent with the object of the test. The source
caused by manual removal of froth. The froth paddle shall not of water must be recorded.
rotate below the pulp surface and not more than 6 mm ( ⁄4 in.) 7.4 Solids Content—The solids content corresponds with
abovethepulplevel.Thedistancebetweentheoverflowlipand thatoftheindustrialpreparationplantslurry,iftheobjectofthe
the edge of the froth paddle shall be at least 3 mm ( ⁄8 in.) but test is to simulate plant conditions. Otherwise, an 8 % solids
not more than 6 mm ( ⁄4 in.). concentration shall be used.
5.1.2 Thepulpinthecellismaintainedataconstantlevelby 7.5 Pulp Level—Maintain between 12.7 and 15.9 mm (0.50
a small tank with an overflow at precisely the desired level to and 0.62 in.) below the lip of the cell as measured with the air
be maintained in the flotation cell. on and stirrer operating.
7.6 Wetting of Coal—Before the addition of reagents and
NOTE 1—Another suitable slurry level control system consists of a
subsequentflotation,itisimportanttoensurethattheproperair
resistance type level probe, a resistance sensor relay, a solenoid valve, and
bubble attachment can take place at the coal-water interface.
associated connecting wires. The level probe is mounted inside the cell
and is connected to the resistance relay which operates the solenoid valve. Wetting is accomplished in the cell by running the impeller at
When the slurry level drops below the tip of the probe, the relay energizes
the r/min specified for the flotation step with the air off.
thesolenoidvalve.Then,makeupwaterflowsintothecell.Whenthelevel
Perform this step for 5 to 10 min before reagent addition. If the
rises up to the probe, the solenoid valve is de-energized, which stops the
sample is in slurry form this wetting step is not necessary.
makeup water flow.
7.7 Reagent Addition—Collector, frother, conditioning
5.2 pH Meter, sensitive to 0.1 units.
agent, or any combination thereof shall be governed by the
5.3 Timing Device that displays cumulative minutes and
requirements of the test. Add reagents to the coal slurry and
seconds.
conditiontoensureproperdistributionofreagents.Conductthe
5.4 Air Flow Meter.
conditioning step at the same impeller speed as the flotation
5.5 Microsyringes or Pipets.
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—Thestartingspeedshallbe1200r/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 Method 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;
6.1 The sample history, moisture content, alteration of the
record any extra time.
inherent moisture, or alteration of the surface properties have
Solids concentration 8 % solids
considerableeffectontheflotationcharacteristicsofthecoal.It
Total volume 2 to 6 L
is important that all samples used in flotation testing are stored
Wetting time 5 min
and handled so as to minimize alteration of the surface pH natural
Impeller speed 1200 r/min
properties. The origin and history of the sample should be
Reagent additions and conditioning times:
recorded. It is imperative that all samples be prepared in a
1. Add collector
similar manner. Since the generation of grade/recovery curves 2. Condition for 90 s
3. Add frother
will involve several individual tests, sample subdivision and
4. Condition for 30 s
preparation must be carefully performed to ensure that each
Air flow rate 3 L/min per litre of pulp
subsample is representative of the original whole sample.
Skimmer rotation 30 r/min
Collection increments 15, 30, 60, 90, 120, 240 (cumulative time
in seconds)
7. Flotation Conditions
7.1 The conditions under which a test program is conducted
will be systematically varied to generate grade/recovery curves
8. Procedure
(Appendix X1). Table 1 outlines recommended starting point
8.1 Calculate the total mass of coal required for the number
conditions for a single laboratory-scale test. These conditions
offlotationtestsbasedonthemeasuredcellvolumeandthetest
solids content.
8.2 Divide the total mass into representative portions by
A suitable slurry level control system, available from C&R Technology, Inc.,
P.O. Box 114, Fall Branch, TN 37656, or equivalent can be used. riffling, in accordance with Method D2013. A few small
D5114–90 (2004)
Y 3 P
increments, totalling no more than 15 % of the total mass, may
c
A 5
P
be either taken from the subsample or added to the subsample f
in order to obtain the exact weight.
where:
8.3 Determine the particle size distribution of one of the
P = is one of the following:
c
portions from 8.2 in accordance with Test Method D4749.
A = percent ash in the froth concentrate fraction,
c
8.4 Rinse the cell thoroughly with water.Add from one half
S = percent sulfur in the froth concentrate fraction,
c
totwothirdsofthetotalrequiredwatertothecell.Confirmthat
B = Btu/lb in the froth concentrate fraction, and
c
the air is turned off. Turn the impeller on and adjust to the
C = percent c
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