1、Designation: D5114 90 (Reapproved 2010)Standard Test Method forLaboratory Froth Flotation of Coal in a Mechanical Cell1This standard is issued under the fixed designation D5114; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the y
2、ear of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONFroth flotation of coal, the separation of ash-bearing minerals from combustibles via differences insurface che
3、mistry, has been steadily increasing in use as a means to treat 600-m (No. 30 U.S.A.Standard Sieve Series) or finer coal. The process is one in which many variables need to be monitoredand regulated. Because of this complexity, rigorous laboratory testing is difficult to standardize.This test method
4、 outlines the types of equipment and procedures to apply on a laboratory scale toisolate key process variables and minimize the variations associated with the design and execution ofa froth flotation test. The objective of the test method is to develop a means by which repeatablegrade/recovery resul
5、ts are ascertained from froth flotation testing of coal without imposingunnecessary 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 frothflotation response. This test met
6、hod does not attempt to define sample preparation and size reductionpractices as part of a froth flotation testing program.This test method also does not completely cover specific procedures for the investigation of flotationkinetics. Such a test is specialized and is highly dependent upon the end u
7、se of the data.1. Scope1.1 This test method covers a laboratory procedure forconducting a single froth flotation test on fine coal (that is,nominal top size of 600 m (No. 30 U.S.A. Standard SieveSeries) or finer) using a defined set of starting point conditionsfor the operating variables.1.2 This te
8、st method does not completely cover specificprocedures for the investigation of flotation kinetics. Such atest is specialized and highly dependent upon the objective ofthe data.1.3 Since optimum conditions for flotation are usually notfound at the specified starting points, suggestions for develop-m
9、ent of grade/recovery curves are given inAppendix X1. Sucha procedure is very case-specific and involves running a seriesof flotation tests in which some of the operating variables arechanged in order to optimize conditions for either yield orgrade.1.4 Laboratory flotation results need not be repres
10、entative ofthe flotation response of coal in full-scale situations, but aconsistent baseline can be established against which full-scaleperformance can be compared.1.5 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system m
11、ay not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.6 This standard does not purport to address the safetyconcerns, if any, associated with its use. It is the responsibility
12、of the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.1.7 Material Safety Data Sheets (MSDS) for reagents usedare to be obtained from suppliers who are to be consultedbefore work with any chemicals used
13、in this test method.2. Referenced Documents2.1 ASTM Standards:2D121 Terminology of Coal and CokeD2013 Practice for Preparing Coal Samples for AnalysisD2015 Test Method for Gross Calorific Value of Coal andCoke by the Adiabatic Bomb Calorimeter31This test method is under the jurisdiction of ASTM Comm
14、ittee D05 on Coaland Coke and is the direct responsibility of Subcommittee D05.07 on PhysicalCharacteristics of Coal.Current edition approved Sept. 1, 2010. Published January 2011. Originallyapproved in 1990. Last previous edition approved in 2004 as D5114 90 (2004).DOI: 10.1520/D5114-90R10.2For ref
15、erenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is
16、referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.D2234/D2234M Practice for Collection of a Gross Sampleof CoalD3173 Test Method for Moisture in the Analysis Sample ofCoal and CokeD3174 Test Method for Ash in
17、the Analysis Sample of Coaland Coke from CoalD3177 Test Methods for Total Sulfur in the AnalysisSample of Coal and CokeD4239 Test Method for Sulfur in the Analysis Sample ofCoal and Coke Using High-Temperature Tube FurnaceCombustionD4749 Test Method for Performing the Sieve Analysis ofCoal and Desig
18、nating Coal Size3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, see Terminology D121.3.2 Definitions of Terms Specific to This Standard:3.2.1 collectora reagent used in froth flotation to promotecontact and adhesion between particles and air bubbles.3.2.2 combustiblest
19、he value obtained by subtracting thedry weight (in percent) of the ash (as determined in TestMethod D3174) from 100 % representing the original weightof the analyzed sample.3.2.3 concentratethe froth product recovered in coal frothflotation.3.2.4 conditioning agentsall chemicals that enhance theperf
20、ormance of the collectors or frothers. Conditioning agentschange the characteristics of the surface of the minerals or theenvironment. There are many subgroups according to function:activators, depressants, emulsifiers, dispersants, flocculants,chelating reagents, froth depressants, pH modifiers, an
21、d soforth.3.2.5 flotation cellthe vessel or compartment in which theflotation test is performed.3.2.6 frotha collection of bubbles and particles on thesurface of a pulp in a froth flotation cell.3.2.7 froth flotationa process for cleaning fine coal inwhich hydrophobic particles, generally coal, atta
22、ch to airbubbles in a water medium and rise to the surface to form afroth. The hydrophilic particles, generally the ash-formingmatter, remain in the water phase.3.2.8 frothera reagent used in froth flotation to control thesize and stability of the air bubbles, principally by reducing thesurface tens
23、ion of water.3.2.9 grade/recoverythe relationship between quality andquantity of the clean coal product. The quality can be definedin terms of ash, sulfur, or Btu content. The quantity can bedesignated as yield or heating value recovery (Btu or combus-tibles).3.2.10 mechanical cella type of flotatio
24、n cell that em-ploys mechanical agitation of a pulp by means of an immersedimpeller (rotor) and stator stirring mechanism. Aeration to thecell can be from an external pressurized air source or self-induced air.3.2.11 natural pHthe measured pH of the pulp prior to theaddition of collector, frother, o
25、r any conditioning agents.3.2.12 pulpa fluid mixture of solids and water, alsoknown as slurry.3.2.13 recoverythe percent of the valuable component(that is, Btu or combustible) from the feed that reports to thefroth concentrate product.3.2.14 solids concentrationthe ratio, expressed as a per-cent, of
26、 the weight (mass) of solids to the sum of the weight ofsolids plus water.3.2.15 tailingsthe underflow product from coal froth flo-tation.3.2.16 yieldthe weight percent of the feed that reports tothe concentrate.4. Significance and Use4.1 This test method uses specific starting point conditionsfor t
27、he froth flotation response to accomplish the following:4.1.1 Assess responses of one or more coals or blends ofcoal, and4.1.2 Evaluate and determine froth flotation circuit perfor-mance.5. Apparatus5.1 Laboratory Flotation Machine, with a minimum volumeof 2 L and a maximum volume of 6 L. Fig. 1 sch
28、ematicallydepicts a batch mechanical flotation cell4which can be used inconjunction with this test method. The major criterion is thatthe unit must be able to provide for constant mechanicalremoval of froth from the cell. In addition, the laboratory unitmust have some means of automatic liquid level
29、 control.5.1.1 An example of a mechanical paddle laboratory frothflotation apparatus is shown in Fig. 1. The froth paddles arerotated at approximately 30 r/min, thus avoiding variationcaused by manual removal of froth. The froth paddle shall notrotate below the pulp surface and not more than 6 mm (1
30、4 in.)4A suitable cell, available from WEMCO, 1796 Tribute Rd., Sacramento, CA95815, or equivalent can be used.FIG. 1 5.5-L Mechanical Paddle Laboratory Froth Flotation CellD5114 90 (2010)2above the pulp level. The distance between the overflow lip andthe edge of the froth paddle shall be at least 3
31、 mm (18 in.) butnot more than 6 mm (14 in.).5.1.2 The pulp in the cell is maintained at a constant level bya small tank with an overflow at precisely the desired level tobe maintained in the flotation cell.NOTE 1Another suitable slurry level control system consists of aresistance type level probe, a
32、 resistance sensor relay, a solenoid valve, andassociated connecting wires.5The level probe is mounted inside the celland is connected to the resistance relay which operates the solenoid valve.When the slurry level drops below the tip of the probe, the relay energizesthe solenoid valve. Then, makeup
33、 water flows into the cell. When the levelrises up to the probe, the solenoid valve is de-energized, which stops themakeup water flow.5.2 pH Meter, sensitive to 0.1 units.5.3 Timing Device that displays cumulative minutes andseconds.5.4 Air Flow Meter.5.5 Microsyringes or Pipets.5.6 Balances, with a
34、 readability of at least 0.5 % of the totalweight.5.7 Vacuum or Pressure Filter, or a filter funnel for gravityfiltration.5.8 Drying Oven with forced air, capable of maintaining amaximum temperature of 40C (104F) and meeting therequirements of Method D2013.5.9 Rinse Bottle.6. Sample Preparation6.1 T
35、he sample history, moisture content, alteration of theinherent moisture, or alteration of the surface properties haveconsiderable effect on the flotation characteristics of the coal. Itis important that all samples used in flotation testing are storedand handled so as to minimize alteration of the s
36、urfaceproperties. The origin and history of the sample should berecorded. It is imperative that all samples be prepared in asimilar manner. Since the generation of grade/recovery curveswill involve several individual tests, sample subdivision andpreparation must be carefully performed to ensure that
37、 eachsubsample is representative of the original whole sample.7. Flotation Conditions7.1 The conditions under which a test program is conductedwill be systematically varied to generate grade/recovery curves(Appendix X1). Table 1 outlines recommended starting pointconditions for a single laboratory-s
38、cale test. These conditionsare for laboratory testing parameters and are not designed tosimulate in-plant operating conditions that can be highlyvariable, such as water temperature and chemistry.7.2 Slurry TemperatureThe operating temperature shallbe 22 6 5C (72 6 9F).7.3 WaterPlant, tap, or distill
39、ed water may be used,whichever is consistent with the object of the test. The sourceof water must be recorded.7.4 Solids ContentThe solids content corresponds withthat of the industrial preparation plant slurry, if the object of thetest is to simulate plant conditions. Otherwise, an 8 % solidsconcen
40、tration shall be used.7.5 Pulp LevelMaintain between 12.7 and 15.9 mm (0.50and 0.62 in.) below the lip of the cell as measured with the airon and stirrer operating.7.6 Wetting of CoalBefore the addition of reagents andsubsequent flotation, it is important to ensure that the proper airbubble attachme
41、nt can take place at the coal-water interface.Wetting is accomplished in the cell by running the impeller atthe r/min specified for the flotation step with the air off.Perform this step for 5 to 10 min before reagent addition. If thesample is in slurry form this wetting step is not necessary.7.7 Rea
42、gent AdditionCollector, frother, conditioningagent, or any combination thereof shall be governed by therequirements of the test. Add reagents to the coal slurry andcondition to ensure proper distribution of reagents. Conduct theconditioning step at the same impeller speed as the flotationstep with t
43、he air flow off.7.7.1 Add the reagents using either a calibrated microsy-ringe or a pipet.7.8 Air FlowRate shall be measured and recorded.7.9 Impeller SpeedThe starting speed shall be 1200 r/min.NOTE 2 Impeller speed is an important variable and should beinvestigated during optimization, depending o
44、n the object of the test.8. Procedure8.1 Calculate the total mass of coal required for the numberof flotation tests based on the measured cell volume and the testsolids content.8.2 Divide the total mass into representative portions byriffling, in accordance with Method D2013. A few smallincrements,
45、totalling no more than 15 % of the total mass, maybe either taken from the subsample or added to the subsamplein order to obtain the exact weight.8.3 Determine the particle size distribution of one of theportions from 8.2 in accordance with Test Method D4749.8.4 Rinse the cell thoroughly with water.
46、 Add from one halfto two thirds of the total required water to the cell. Confirm thatthe air is turned off. Turn the impeller on and adjust to thedesired speed. Transfer a sample into the cell. Be careful toremove all of the coal from the sides of the transfer container.5A suitable slurry level cont
47、rol system, available from Crecord any extra time.Solids concentration 8 % solidsTotal volume 2 to 6 LWetting time 5 minpH naturalImpeller speed 1200 r/minReagent additions and conditioning times:1. Add collector2. Condition for 90 s3. Add frother4. Condition for 30 sAir flow rate 3 L/min per litre
48、of pulpSkimmer rotation 30 r/minCollection increments 15, 30, 60, 90, 120, 240 (cumulative timein seconds)D5114 90 (2010)3Continue this wetting step for approximately 5 min. Add mostof the additional water but reserve a sufficient quantity forrinsing (see 8.8).8.5 Determine the pH and temperature of
49、 the slurry with theair turned off.8.6 Start the timing device. Add the collector to the slurryand condition for 90 s. After this first conditioning step, use asmall quantity of rinse water to wash down any coal that isclinging to the sides of the cell.8.7 Again start the timer. Add the frother to the slurry andcondition for 30 s.8.8 After this second conditioning step, wash down any coalthat is clinging to the sides of the cell. At this time, the pulplevel shall be the operating level specified in 7.5.8.9 Confirm that the water valve is open to
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