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1、BRITISH STANDARD BS 7530-2: 1995 Methods for Froth flotation testing of hard coal Part 2: Evaluation of flotation characteristics Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 13:55:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7530-2:1995 This British Stan
2、dard, having been prepared under the direction of the Materials and Chemicals Sector Board (I/-), was published under the authority of the Standards 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 Dr
3、aft for comment 94/502663 DC ISBN 0 580 23718 4 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee SFI/5, Coal preparation, upon which the following bodies were represented: British Coal Corporation Coal Preparation Plant As
4、sociation Low Temperature Coal Distillers Association of Great Britain Ltd. Minerals Engineering Society Amendments issued since publication Amd. No.DateComments Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 13:55:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI
5、BS 7530-2:1995 BSI 07-1999i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope1 2 References1 3 Definitions1 4 Principle1 5 Reagents1 6 Apparatus1 7 Sampling and preparation of test sample3 8 Flotation test conditions3 9 Procedure3 10 Presentation of results4 11 Test report4
6、 Figure 1 Typical flotation machine2 Figure 2 Detail of flotation cell and impeller2 Figure 3 Example of plot of cumulative percentage by mass of froth concentrate/tailings versus cumulative percentage ash using data from Table 15 Figure 4 Example of plot of “Mayer curve” using data from Table 15 Ta
7、ble 1 Example of presentation of froth flotation data and calculations for flotation characteristics curves4 List of references Inside back cover Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 13:55:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7530-2:1995 i
8、i BSI 07-1999 Foreword This Part of BS 7530 was prepared by Technical Committee SFI/5. It is one of two Parts giving methods for froth flotation testing of hard coal. BS 7530-1 sets out the procedure for a laboratory test to determine whether or not a coal is amenable to up-grading in quality by fro
9、th flotation. It is accepted that variation of the many parameters in the froth flotation process can be 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
10、 process. To facilitate the determination of how a particular coal will respond to froth flotation, a method 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 met
11、hod provides a basis to vary test parameters to explore any special flotation characteristics. This standard 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 expec
12、ted that the use of this method will provide a tool for comparison of flotation characteristics. From the 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 r
13、epresents a reliable means of comparing the flotation response of different samples. A British Standard 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 its
14、elf confer immunity from legal obligations. Summary of pages This document comprises a front cover, an 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 i
15、ndicated in the amendment table on the inside front cover. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 13:55:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7530-2:1995 BSI 07-19991 1 Scope This Part of BS 7530 describes a laboratory method for evaluation o
16、f the froth flotation characteristics of hard coal, of particle size less than 0.5 mm. It is applicable to coal in powder form or in the form of a slurry. 2 References 2.1 Normative references This Part of BS 7530 incorporates, by dated or undated reference, provisions from other publications. These
17、 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 publication apply to this Part of BS 7530 only when incorp
18、orated 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 BS 7530 refers to other publications that provide information or guidance. The editions of these public
19、ations 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 BS 7530, the definitions given in BS 3552 apply. 4 Principle A test portion of coal is mixed with water to for
20、m 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 impeller. To study differing flotation characterist
21、ics, 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 Reagents 5.1 General. Use only reagents of recognized a
22、nalytical grade and only water conforming to grade 3 of BS 3978:1987. 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 diluting 1 ml of MIBC to 1 l using water (see 5.1). All dosages
23、of MIBC stated refer to this solution. 6 Apparatus 6.1 Flotation machine, as described in 5.1 of BS 7530-1:1992, consisting of a mechanical impeller type flotation machine designed for laboratory scale flotation testing, comprising the following: a) a flotation cell, of capacity 2.5 l to 10 l, made
24、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 approximately 6 m/s. The impeller shall be positioned centrally with a clearance of 6 mm 1 mm above the bottom
25、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 at a constant level during the test.
26、 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 holding individual samples of froth and t
27、ailings. 6.7 Timing device, accurate to 1 s and capable of being zeroed and started as required. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 13:55:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7530-2:1995 2 BSI 07-1999 Figure 1 Typical flotation machine F
28、igure 2 Detail of flotation cell and impeller Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 13:55:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7530-2:1995 BSI 07-19993 7 Sampling and preparation of test sample Take a gross sample which is at least five tim
29、es the mass required for a single flotation test (see 9.1). Where the sample for flotation testing is obtained in slurry form, allow it to settle for at least 12 h and then remove the supernatant water. Mix the resulting thickened slurry and determine its solids content. NOTE 1The history and method
30、 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 replicate tests are required together with subsampling for size
31、 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 BS 1017-1. NOTE 2The use of chemical additives to enhance the settlement of a slurry and the use of heat to dri
32、ve 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 operating speed shall be such as to give an air flow ra
33、te of 2 ls1 m2 of the pulp surface area with the air inlet valve fully open; an impeller tip speed of approximately 6 m/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 the required range of 0.25 l.s1 m2 to 2.0 ls1m2 of pulp
34、 surface area (see 9.3.5). 8.4 Pulp level This shall be 20 mm 2 mm 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 form, calculate the mass of the test portion requ
35、ired from the measured volume of the flotation cell at the pulp level (see 8.4) and the moisture content of the test sample (see BS 7530-1) to give a solids content of 100 g (dry basis) per litre of pulp. In the case of a slurry, calculate the required mass of thickened slurry from the volume of the
36、 flotation cell at the pulp level (see 8.4) and the solids content of the thickened slurry to give a solids content of 100 g (dry basis) per litre of pulp. Weigh the test portion to the nearest 0.1 g. 9.2 Preparation If the test portion is in powder form, half fill the flotation cell with water (see
37、 5.1) 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 for 10 min at the operating impeller speed with the air inlet valve closed. If the test portion is a thickened slurry, transfer it to the cell and ad
38、d water to the required level. Agitate for 2 min 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 (see 5.2) at a dose rate of 90 ml/t
39、of dry solids (based on the original feed mass) and condition for 1 min without air. Add the frother (see 5.3) at a dose rate of 10 l/t of dry solids and condition for an additional 10 s without air. Open the air valve and control the air flow rate to 2 ls1m2 of pulp surface area. Allow froth to bui
40、ld up for 30 s, then remove the froth concentrate for a further 1 min. 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 tailings 1). 9.3.4 Re-i
41、ntroduce 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 of 180 ml/t, based on the original feed mass, and condition for 1 min with the air valve closed. Add the frother at
42、 a dose rate of 20 l/t and condition for an additional 10 s with the air valve closed. 9.3.5 Collect nine froth concentrates in separate containers marked 1 to 9, over consecutive times as follows. a) Open the air valve and adjust the flow rate to 0.25 ls1m2 of pulp surface area. Collect froth conce
43、ntrate 1 in a container for 30 s. Change container and collect froth concentrate 2 for the following 30 s. b) Change the container and adjust the air flow rate to 0.5 ls1m2 of pulp surface area. Collect froth concentrate 3 for 30 s. Change container and collect froth concentrate 4 for the following
44、30 s. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 13:55:30 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7530-2:1995 4 BSI 07-1999 c) Change the container and adjust the air flow rate to 1 ls1m2 of pulp surface area. Collect froth concentrate 5 for 60 s. Cha
45、nge the container and collect froth concentrate 6 for the following 60 s. d) Change the container and adjust the air flow rate to 2 ls1m2 of pulp surface area. Collect froth concentrate 7 for 60 s. Change the container and collect froth concentrate 8 for the following 60 s. e) Change the container a
46、nd collect froth concentrate 9 until flotation is completed. 9.3.6 Remove the tailings for analysis (designated tailings 2). 9.3.7 Dry, weigh and analyse all products in accordance with the relevant Parts of BS 1016. NOTE 1All reagent additions should be made below the surface of the pulp. NOTE 2All
47、 air flow rates should be 10 % of the stated value and adjustments to air flow rates made within 10 s. NOTE 3The recommended procedure for froth removal is as follows: use two froth scrapers; wipe the cell walls and standpipes at least once during each concentrate removal; remove froth from the surf
48、ace approximately once every 15 s. 10 Presentation of results Tabulate the percentage by mass of froth concentrate and tailings together with the results of ash determinations and/or other tests and calculate the results as shown in the example given in Table 1. Present the results graphically by pl
49、otting 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 the “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 BS 7530-2; e) the percentages by mass of froth concentrates and tailings; f) the results for any other properties determined; g)