1、BRITISH STANDARD BS 7530-2: 1995 Methods for Froth flotation testing of hard coal Part 2: Evaluation of flotation characteristicsBS7530-2:1995 This British Standard, having been prepared under the direction of the Materials and Chemicals Sector Board (I/-), was published under the authority of the S
2、tandards Board and comes into effect on 15 April 1995 BSI 07-1999 The following BSI references relate to the work on this standard: Committee reference SFI/5 Draft for comment 94/502663 DC ISBN 0 580 23718 4 Committees responsible for this British Standard The preparation of this British Standard wa
3、s entrusted to Technical Committee SFI/5, Coal preparation, upon which the following bodies were represented: British Coal Corporation Coal Preparation Plant Association Low Temperature Coal Distillers Association of Great Britain Ltd. Minerals Engineering Society Amendments issued since publication
4、 Amd. No. Date CommentsBS 7530-2:1995 BSI 07-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 References 1 3 Definitions 1 4 Principle 1 5 Reagents 1 6 Apparatus 1 7 Sampling and preparation of test sample 3 8 Flotation test conditions 3 9 Procedure 3 10 Present
5、ation of results 4 11 Test report 4 Figure 1 Typical flotation machine 2 Figure 2 Detail of flotation cell and impeller 2 Figure 3 Example of plot of cumulative percentage by mass of froth concentrate/tailings versus cumulative percentage ash using data from Table 1 5 Figure 4 Example of plot of “Ma
6、yer curve” using data from Table 1 5 Table 1 Example of presentation of froth flotation data and calculations forflotation characteristics curves 4 List of references Inside back coverBS7530-2:1995 ii BSI 07-1999 Foreword This Part of BS7530 was prepared by Technical Committee SFI/5. It is one of tw
7、o Parts giving methods for froth flotation testing of hard coal. BS7530-1 sets out the procedure for a laboratory test to determine whether or not a coal is amenable to up-grading in quality by froth flotation. It is accepted that variation of the many parameters in the froth flotation process can b
8、e used to effect the beneficiation of the product. This Part of this British Standard describes methods of applying certain test conditions to reveal the relative response of coals to the flotation process. To facilitate the determination of how a particular coal will respond to froth flotation, a m
9、ethod of controlling the recovery of froth is used. This is done by inhibiting the process to a degree, determining the rate at which a coal reacts and by progressively sampling the froth. This method provides a basis to vary test parameters to explore any special flotation characteristics. This sta
10、ndard is applicable to a wide range of coals and provides a method of comparison of flotation behaviour and will facilitate the exchange of information relating to specific performance. It is expected that the use of this method will provide a tool for comparison of flotation characteristics. From t
11、he results of the standard test it is possible to draw evaluation curves similar to those obtained from float and sink testing of raw coal. Because of the high reproducibility of results the test represents a reliable means of comparing the flotation response of different samples. A British Standard
12、 does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an
13、inside front cover, pages i and ii, pages 1 to 6, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS7530-2:1995 BSI 07-1999 1 1 Scope This Part
14、 of BS7530 describes a laboratory method for evaluation of the froth flotation characteristics of hard coal, of particle size less than0.5mm. It is applicable to coal in powder form or in the form of a slurry. 2 References 2.1 Normative references This Part of BS7530 incorporates, by dated or undate
15、d reference, provisions from other publications. These normative references are made at the appropriate places in the text and the cited publications are listed on the inside back cover. For dated references, only the edition cited applies; any subsequent amendments to or revisions of the cited publ
16、ication apply to this Part of BS7530 only when incorporated in the reference by amendment or revision. For undated references, the latest edition of the cited publication applies, together with any amendments. 2.2 Informative references This Part of BS7530 refers to other publications that provide i
17、nformation or guidance. The editions of these publications current at the time of issue of this standard are listed on the inside back cover, but reference should be made to the latest editions. 3 Definitions For the purposes of this Part of BS7530, the definitions given in BS3552 apply. 4 Principle
18、 A test portion of coal is mixed with water to form a suspension in the flotation cell, or a test portion of slurry is added to the cell and diluted. A collector and frother are added, the suspension is conditioned and air is then introduced to the cell while agitation is maintained by means of an i
19、mpeller. To study differing flotation characteristics, the flotation operation is inhibited in two ways, relating to reagent dosage rate in the first stage of the test and to air flow rate in the second stage. A number of froth increments are obtained which give spaced points for comparison. 5 Reage
20、nts 5.1 General. Use only reagents of recognized analytical grade and only water conforming to grade3 of BS3978:1987. 5.2 Collector. n-Dodecane used undiluted. 5.3 Frother. Prepare a solution of 0.1% (V/V)4-methylpentan-2-ol (otherwise known as methyl isobutyl carbinol or MIBC) by diluting1ml of MIB
21、C to1 l using water (see 5.1). All dosages of MIBC stated refer to this solution. 6 Apparatus 6.1 Flotation machine, as described in 5.1 of BS7530-1:1992, consisting of a mechanical impeller type flotation machine designed for laboratory scale flotation testing, comprising the following: a) a flotat
22、ion cell, of capacity2.5l to10l, made from an inert material such as stainless steel, glass or polymethyl methacrylate; b) an impeller assembly, capable of being driven so that the periphery of the impeller moves at a speed of approximately6m/s. The impeller shall be positioned centrally with a clea
23、rance of 6 mm 1 mm above the bottom of the cell; c) a means of supplying air to the impeller. A typical flotation machine is shown in Figure 1 and Figure 2. 6.2 Air flowmeter, with a needle valve to control the air flow rate to the flotation cell. 6.3 Constant level device, for maintaining the pulp
24、at a constant level during the test. NOTEThe level may be maintained by the manual addition of water. 6.4 Two scrapers, for removing the froth from the entire surface of the pulp, including the area behind the standpipe. 6.5 Calibrated micro-syringe or micro-pipette. 6.6 Containers, capable of holdi
25、ng individual samples of froth and tailings. 6.7 Timing device, accurate to 1 s and capable of being zeroed and started as required. BS7530-2:1995 2 BSI 07-1999 Figure 1 Typical flotation machine Figure 2 Detail of flotation cell and impellerBS7530-2:1995 BSI 07-1999 3 7 Sampling and preparation of
26、test sample Take a gross sample which is at least five times the mass required for a single flotation test (see9.1). Where the sample for flotation testing is obtained in slurry form, allow it to settle for at least12 h and then remove the supernatant water. Mix the resulting thickened slurry and de
27、termine its solids content. NOTE 1The history and method of preparation of the sample can affect the flotation characteristics of the coal. The source of the sample should be recorded and care should be taken to ensure that samples for comparative tests are prepared in the same manner. Since replica
28、te tests are required together with subsampling for size analysis and other tests, care should be taken in mixing and subdivision of the original sample. When applicable, sampling and division of samples should be carried out in accordance with BS1017-1. NOTE 2The use of chemical additives to enhanc
29、e the settlement of a slurry and the use of heat to drive off water should not be employed because such practices can affect the flotation characteristics of the coal. 8 Flotation test conditions 8.1 Test temperature The test temperature shall be 20 C 10 C. 8.2 Impeller operating speed The impeller
30、operating speed shall be such as to give an air flow rate of 2ls 1 m 2of the pulp surface area with the air inlet valve fully open; an impeller tip speed of approximately6m/s is usually suitable. 8.3 Air flow rate The air inlet valve shall be used to control the air flow rate during the test over th
31、e required range of0.25l.s 1 m 2to2.0ls 1 m 2of pulp surface area (see9.3.5). 8.4 Pulp level This shall be20mm 2mm below the overflow lip of the cell when the impeller is rotating at the operating speed and the air inlet valve is closed. 9 Procedure 9.1 Test portion If the feed sample is in powder f
32、orm, calculate the mass of the test portion required from the measured volume of the flotation cell at the pulp level (see8.4) and the moisture content of the test sample (seeBS7530-1) to give a solids content of100g (dry basis) per litre of pulp. In the case of a slurry, calculate the required mass
33、 of thickened slurry from the volume of the flotation cell at the pulp level (see8.4) and the solids content of the thickened slurry to give a solids content of100g (dry basis) per litre of pulp. Weigh the test portion to the nearest0.1g. 9.2 Preparation If the test portion is in powder form, half f
34、ill the flotation cell with water (see5.1) and start the impeller with the air inlet valve closed. Gradually add the test portion and top up to the required level with water. Then agitate for10min at the operating impeller speed with the air inlet valve closed. If the test portion is a thickened slu
35、rry, transfer it to the cell and add water to the required level. Agitate for2min at the operating impeller speed with the air inlet valve closed. 9.3 Flotation test 9.3.1 Carry out the following procedure seven times, collecting the seven froth concentrates in the same container. Add n-dodecane (se
36、e5.2) at a dose rate of90ml/t of dry solids (based on the original feed mass) and condition for1 min without air. Add the frother (see 5.3) at a dose rate of10l/t of dry solids and condition for an additional10s without air. Open the air valve and control the air flow rate to 2ls 1 m 2of pulp surfac
37、e area. Allow froth to build up for30s, then remove the froth concentrate for a further1min. Close the air valve. 9.3.2 Remove any froth remaining on the surface of the pulp, the standpipe and the cell walls and add this to the froth concentrates. 9.3.3 Remove the tailings for analysis (designated t
38、ailings1). 9.3.4 Re-introduce the combined froth concentrates to the flotation cell and make up to the required level with water. Start the impeller with the air valve closed. Add n-dodecane at a dose rate of180ml/t, based on the original feed mass, and condition for 1 min with the air valve closed.
39、 Add the frother at a dose rate of20l/t and condition for an additional10s with the air valve closed. 9.3.5 Collect nine froth concentrates in separate containers marked1 to9, over consecutive times as follows. a) Open the air valve and adjust the flow rate to0.25 ls 1 m 2of pulp surface area. Colle
40、ct froth concentrate1in a container for30s. Change container and collect froth concentrate2for the following30s. b) Change the container and adjust the air flow rate to0.5ls 1 m 2of pulp surface area. Collect froth concentrate3 for30s. Change container and collect froth concentrate4 for the followin
41、g30s.BS7530-2:1995 4 BSI 07-1999 c) Change the container and adjust the air flow rate to1ls 1 m 2of pulp surface area. Collect froth concentrate5 for 60s. Change the container and collect froth concentrate6 for the following60s. d) Change the container and adjust the air flow rate to 2ls 1 m 2of pul
42、p surface area. Collect froth concentrate7 for60s. Change the container and collect froth concentrate8 for the following60s. e) Change the container and collect froth concentrate9 until flotation is completed. 9.3.6 Remove the tailings for analysis (designated tailings2). 9.3.7 Dry, weigh and analys
43、e all products in accordance with the relevant Parts of BS1016. NOTE 1All reagent additions should be made below the surface of the pulp. NOTE 2All air flow rates should be 10 % of the stated value and adjustments to air flow rates made within10s. NOTE 3The recommended procedure for froth removal is
44、 as follows: use two froth scrapers; wipe the cell walls and standpipes at least once during each concentrate removal; remove froth from the surface approximately once every15s. 10 Presentation of results Tabulate the percentage by mass of froth concentrate and tailings together with the results of
45、ash determinations and/or other tests and calculate the results as shown in the example given in Table 1. Present the results graphically by plotting the cumulative percentage by mass of froth concentrate/tailings versus cumulative percentage by mass of ash as shown in Figure 3 and/or by plotting th
46、e “Mayer curve” as shown in Figure 4. 11 Test report The test report shall include the following: a) the date of the test; b) the complete identification of the sample; c) the history of the sample; d) reference to the method used, ie BS7530-2; e) the percentages by mass of froth concentrates and ta
47、ilings; f) the results for any other properties determined; g) any unusual features noted during the tests; h) any operation not specified in this standard or the standards to which reference is made, or regarded as optional. Table 1 Example of presentation of froth flotation data and calculations f
48、or flotation characteristics curves SOURCE: Mansfield SAMPLE DATE: 24 March 1992 SIZE FRACTION: 0.5mm 1 2 3 4 5 6 7 Froth flotation product Percentage by mass of concentrate /tailings Percentage by mass of ash Quantity of ash (2) (3) a Cumulative percentage by mass of concentrate/ tailings, C (2) Cu
49、mulative quantity of ash, C (4) Cumulative percentage of ash, (6) (5) % % g 100 % g 100 % Froth 1 Froth 2 Froth 3 Froth 4 Froth 5 Froth 6 Froth 7 Froth 8 Froth 9 Tailings 2 Tailings 1 9.9 16.1 14.3 7.4 6.6 2.5 3.6 nil nil 5.0 34.6 4.9 5.0 5.6 6.2 7.4 9.4 18.4 69.2 85.8 48.51 80.50 80.08 45.88 48.84 23.50 66.24 346.00 2968.68 9.9 26.0 40.3 47.7 54.3 56.8 60.4 65.4 100.0 48.51 129.01 209.09 254.97 303.81 327.31 393.55 739.55 3708.23 4.9 5.0 5.2 5.3 5.6 5.8 6.5 11.3 37.1 Totals 1000 37.1 3708.23 NOTEF
