1、 Reference number ISO 8858-3:2004(E) ISO 2004INTERNATIONAL STANDARD ISO 8858-3 First edition 2004-08-15 Hard coal Froth flotation testing Part 3: Release evaluation Houille Essais de flottation Partie 3: valuation des missions ISO 8858-3:2004(E) PDF disclaimer This PDF file may contain embedded type
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6、le 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2004 All rights reservedISO 8858-3:2004(E) ISO 2004 All rights reserved iiiContents Page Foreword iv Introduction v 1 Scope 1 2 Normative references. 1 3 Terms
7、 and definitions. 1 4 Principle. 1 5 Reagents 1 6 Apparatus. 2 7 Sampling and preparation of test sample 4 8 Flotation test conditions 5 8.1 Test temperature. 5 8.2 Impeller operating speed 5 8.3 Air flow rate . 5 8.4 Pulp level 5 9 Procedure. 5 9.1 Test portion. 5 9.2 Preparation 5 9.3 Flotation te
8、st 5 10 Presentation of results . 6 11 Test report 7 Bibliography . 9 ISO 8858-3:2004(E) iv ISO 2004 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International St
9、andards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also
10、 take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committee
11、s is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possib
12、ility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 8858-3 was prepared by Technical Committee ISO/TC 27, Solid mineral fuels, Subcommittee SC 1, Coal preparation: Terminology and p
13、erformance. ISO 8858 consists of the following parts, under the general title Hard coal Froth flotation testing: Part 1: Laboratory procedure Part 2: Sequential evaluation Part 3: Release evaluation ISO 8858-3:2004(E) ISO 2004 All rights reserved vIntroduction The froth flotation of coal has widespr
14、ead application for the recovery of fine coal particles and their separation from unwanted mineral matter. The response of coal to the froth flotation process is measured initially by a laboratory scale test. ISO 8858-1:1990 provides a means of evaluating the general flotation characteristics of a c
15、oal under a set of specified conditions and will not necessarily indicate the full potential of that coal. 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 ISO 8858 describes methods of applying c
16、ertain 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 method of controlling the recovery of froth is used. This is done by inhibiting the process to a degree, determining t
17、he rate at which coal reacts and by progressively sampling the froth. This method provides a basis to vary test parameters to explore any special flotation characteristics. This part of ISO 8858 is applicable to a wide range of coals and provides a method of comparison of flotation behaviour, and wi
18、ll 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 the results of the standard test, it is possible to draw evaluation curves similar to those obtained from the f
19、loat and sinking of coal. Because of the high reproducibility of results, the test represents a reliable means of comparing the flotation response of different samples. INTERNATIONAL STANDARD ISO 8858-3:2004(E) ISO 2004 All rights reserved 1Hard coal Froth flotation testing Part 3: Release evaluatio
20、n 1 Scope This part of ISO 8858 describes a laboratory method for release evaluation of 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 Normative references The following referenced documents a
21、re indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 1213-1:1993, Solid mineral fuels Vocabulary Part 1: Terms relating to coal prepar
22、ation ISO 3696:1987, Water for analytical laboratory use Specification and test methods ISO 8858-1:1990, Hard coal Froth flotation testing Part 1: Laboratory procedure 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 1213-1 apply. 4 Principle A test p
23、ortion 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 impeller.
24、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 Reagents Use o
25、nly reagents of recognized analytical grade and the following. 5.1 Water, conforming to grade 3 of ISO 3696. 5.2 Collector, undiluted n-dodecane. ISO 8858-3:2004(E) 2 ISO 2004 All rights reserved5.3 Frother. Prepare a solution of 0,1 % (V/V) 4-methylpentan-2-ol (formerly called methyl isobutyl carbi
26、nol or MIBC) by diluting 1 ml of MIBC to 1 litre using water (see 5.1). All dosages of MIBC stated refer to this solution. 6 Apparatus 6.1 Flotation machine As described in 6.1 of ISO 8858-1:1990, consisting of a mechanical impeller-type flotation machine designed for laboratory-scale flotation test
27、ing, comprising the following. a) A flotation cell, of capacity approximately 3,5 litres, 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 approximately 5
28、,7 m/s. The impeller shall be positioned centrally with a clearance of no more than 5 mm from the base of the cell. c) A means of supplying air to the impeller. A typical flotation machine is shown in Figures 1 and 2. 6.2 Air flowmeter, with a needle valve to control the air flow rate to the flotati
29、on cell. 6.3 Constant level device, for maintaining the pulp at a constant level during the test. NOTE The 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 mi
30、cro-syringe or micro-pipette. 6.6 Containers, capable of holding individual samples of froth and tailings. 6.7 Timing device, accurate to 1 s and capable of being zeroed and started as required. ISO 8858-3:2004(E) ISO 2004 All rights reserved 3Key 1 drive mechanism 2 cell 3 metal base 4 levelling sc
31、rews Figure 1 Typical flotation machine ISO 8858-3:2004(E) 4 ISO 2004 All rights reservedKey 1 cell 2 hood diffuser 3 impeller 4 impeller shaft Figure 2 Detail of flotation cell and impeller 7 Sampling and preparation of test sample Take a gross sample which is at least five times the mass required
32、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. The history and method of preparation of the samp
33、le 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 analysis and other tests,
34、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 ISO 13909-2. The use of chemical additives to enhance the settlement of a slurry and the use of heat to drive off water should not be empl
35、oyed because such practices can affect the flotation characteristics of the coal. ISO 8858-3:2004(E) ISO 2004 All rights reserved 58 Flotation test conditions 8.1 Test temperature The test temperature shall be as specified in ISO 8858-1 and shall be recorded in the test report. 8.2 Impeller operatin
36、g speed The impeller operating speed shall be such as to give an air flow rate of 2 ls 1 per square metre of the pulp surface area with the air inlet valve fully open; an impeller tip speed of approximately 5,7 m/s is usually suitable. 8.3 Air flow rate The air inlet valve shall be used to control t
37、he air flow rate during the test over the required range of 0,25 ls 1per square metre to 2,0 ls 1per square metre of pulp 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
38、 is closed. 9 Procedure 9.1 Test portion If the feed sample is in powder form, calculate the mass of the test portion required from the measured volume of the flotation cell at the pulp level (see 8.4) and the moisture content of the test sample (see ISO 8858-1) to give a solids content of 100 g (dr
39、y basis) per litre of pulp. In the case of a slurry, calculate the required mass of thickened slurry from the volume of the 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 portio
40、n to the nearest 0,1 g. 9.2 Preparation If the test portion is in powder form, half fill the flotation cell with water (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 im
41、peller speed with the air inlet valve closed. If the test portion is a thickened slurry, transfer it to the cell and add 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 ti
42、mes, collecting the seven froth concentrates in the same container. Add n-dodecane (5.2) at a dose rate of 90 ml/t of dry solids (based on the original feed mass) and condition for 1 min without air. Add the frother (5.3) at a dose rate of 10 l/t of dry solids and condition for an additional 10 s wi
43、thout air. Open the air valve and control the air flow rate to 2 ls 1 per square metre of pulp surface area. Allow froth to build up for 30 s, then remove the froth concentrate for a further 1 min. Close the air valve. ISO 8858-3:2004(E) 6 ISO 2004 All rights reserved9.3.2 Remove any froth remaining
44、 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 Add the combined froth concentrates to the flotation cell again and make up to the required level with water. Start the impeller
45、 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 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
46、 separate containers marked 1 to 9, over consecutive times as follows. a) Open the air valve and adjust the flow rate to 0,25 ls 1per square metre of pulp surface area. Collect froth concentrate 1 in a container for 30 s. Change the container and collect froth concentrate 2 for the following 30 s. b
47、) Change the container and increase the air flow rate to 0,5 ls 1 per square metre of pulp surface area. Collect froth concentrate 3 for 30 s. Change the container and collect froth concentrate 4 for the following 30 s. c) Change the container and increase the air flow rate to 1 ls 1per square metre
48、 of pulp surface area. Collect froth concentrate 5 for 60 s. Change the container and collect froth concentrate 6 for the following 60 s. d) Change the container and increase the air flow rate to 2 ls 1 per square metre of pulp surface area. Collect froth concentrate 7 for 60 s. Change the container
49、 and collect froth concentrate 8 for the following 60 s. e) Change the container and 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 International Standards. All reagent additions should be made below the surface of the pulp. All air flow rates should be 10 % of the stated value and adjustments to air flow rates made within 10 s. The recomme
