1、Designation: D 5114 90 (Reapproved 2004)Standard Test Method forLaboratory Froth Flotation of Coal in a Mechanical Cell1This standard is issued under the fixed designation D 5114; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、 year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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
3、chemistry, 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 met
4、hod 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 re
5、sults 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
6、method 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 en
7、d use 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
8、 test 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 develo
9、p-ment of grade/recovery curves are given in Appendix 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 re
10、presentative 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 SI units are to be regarded asstandard. The values in parentheses are provided for informa-tion only. The v
11、alues stated in each system may not be exactequivalents; therefore, each system must be used indepen-dently of the other, without combining values in any way.1.6 This standard does not purport to address the safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this
12、 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 in this test method
13、.2. Referenced Documents2.1 ASTM Standards:2D 121 Terminology of Coal and CokeD 2013 Practice of Preparing Coal Samples for AnalysisD 2015 Test Method for Gross Calorific Value of Coal andCoke by the Adiabatic Bomb Calorimeter3D 2234/D 2234M Practice for Collection of a Gross Sampleof Coal21This tes
14、t method is under the jurisdiction of ASTM Committee D05 on Coaland Coke and is the direct responsibility of Subcommittee D05.07 on PhysicalCharacteristics of Coal.Current edition approved April 1, 2004. Published May 2004. Originallyapproved in 1990. Last previous edition approved in 1998 as D 5114
15、 90 (1998).2For referenced 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.1Copyright ASTM International, 100 Barr
16、 Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.D 3173 Test Method for Moisture in the Analysis Sample ofCoal and CokeD 3174 Test Method for Ash in the Analysis Sample of Coaland Coke from CoalD 3177 Test Methods for Total Sulfur in the AnalysisSample of Coal and CokeD 42
17、39 Test Methods for Sulfur in the Analysis Sample ofCoal and Coke Using High-Temperature Tube FurnaceCombustion MethodsD 4749 Test Method for Performing the Sieve Analysis ofCoal and Designating Coal Size3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, see Terminology D
18、 121.3.2 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 combustiblesthe value obtained by subtracting thedry weight (in percent) of the ash (as determined in TestMethod D 3174) fro
19、m 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 theperformance of the collectors or frothers. Conditioning agentschange the characteristics of the surface of the min
20、erals or theenvironment. There are many subgroups according to function:activators, depressants, emulsifiers, dispersants, flocculants,chelating reagents, froth depressants, pH modifiers, and soforth.3.2.5 flotation cellthe vessel or compartment in which theflotation test is performed.3.2.6 frotha c
21、ollection 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, attach to airbubbles in a water medium and rise to the surface to form afroth. The hydrophilic particles, generall
22、y 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 tension of water.3.2.9 grade/recoverythe relationship between quality andquantity of the clean coal product. The q
23、uality 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 flotation cell that em-ploys mechanical agitation of a pulp by means of an immersedimpeller (rotor) and stator stirrin
24、g 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, or any conditioning agents.3.2.12 pulpa fluid mixture of solids and water, alsoknown as slurry.3.2.13 recoveryt
25、he 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 the weight (mass) of solids to the sum of the weight ofsolids plus water.3.2.15 tailingsthe underflow product
26、 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 the froth flotation response to accomplish the following:4.1.1 Assess responses of one or more coals or blends
27、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 schematicallydepicts a batch mechanical flotation cell4which can be used inconjunction with this test method. The
28、 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 control.5.1.1 An example of a mechanical paddle laboratory frothflotation apparatus is shown in Fig. 1. The f
29、roth 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 (14 in.)above the pulp level. The distance between the overflow lip and4A suitable cell, available from WEMCO, 1
30、796 Tribute Rd., Sacramento, CA95815, or equivalent can be used.FIG. 1 5.5-L Mechanical Paddle Laboratory Froth Flotation CellD 5114 90 (2004)2the edge of the froth paddle shall be at least 3 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
31、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 resistance sensor relay, a solenoid valve, andassociated connecting wires.5The level probe is mounted inside
32、 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 water flows into the cell. When the levelrises up to the probe, the solenoid valve is de-energized, which st
33、ops 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 readability of at least 0.5 % of the totalweight.5.7 Vacuum or Pressure Filter, or a filter funnel for gravi
34、tyfiltration.5.8 Drying Oven with forced air, capable of maintaining amaximum temperature of 40C (104F) and meeting therequirements of Method D 2013.5.9 Rinse Bottle.6. Sample Preparation6.1 The sample history, moisture content, alteration of theinherent moisture, or alteration of the surface proper
35、ties 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 surfaceproperties. The origin and history of the sample should berecorded. It is imperative that all samples
36、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 eachsubsample is representative of the original whole sample.7. Flotation Conditions7.1 The conditions unde
37、r 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-scale test. These conditionsare for laboratory testing parameters and are not designed tosimulate in-plant op
38、erating 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 distilled water may be used,whichever is consistent with the object of the test. The sourceof water must be recorde
39、d.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 % solidsconcentration shall be used.7.5 Pulp LevelMaintain between 12.7 and 15.9 mm (0.50and 0.62 in.) below the lip of th
40、e 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 attachment can take place at the coal-water interface.Wetting is accomplished in the cell by running the impeller at
41、the 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 Reagent AdditionCollector, frother, conditioningagent, or any combination thereof shall be governed by therequi
42、rements 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 the air flow off.7.7.1 Add the reagents using either a calibrated microsy-ringe or a pipet.7.8 Air FlowRate s
43、hall 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 on the object of the test.8. Procedure8.1 Calculate the total mass of coal required for the numberof flotatio
44、n 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 D 2013. A few smallincrements, totalling no more than 15 % of the total mass, maybe either taken from the subsample or added to the subsam
45、plein 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 D 4749.8.4 Rinse the cell thoroughly with water. Add from one halfto two thirds of the total required water to the cell. Confirm thatthe air is turned off
46、. 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 control system, available from Crecord any extra time.Solids concentration 8 % solidsTotal volume 2 to 6 LWett
47、ing 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 of pulpSkimmer rotation 30 r/minCollection increments 15, 30, 60, 90, 120, 240 (cumulative timein seconds)
48、D 5114 90 (2004)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 the slurry with theair turned off.8.6 Start the timing device. Add the collector to the slurryand condit
49、ion 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 the constantlevel control system.8.10 Turn on the froth paddles and start the air flow.8.11 Start the fro
