1、BRITISH STANDARD BS ISO 8858-3:2004 Hard coal Froth flotation testing Part 3: Release evaluation ICS 73.040 BS ISO 8858-3:2004 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 3 October 2005 BSI 3 October 2005 ISBN 0 580 46687 6 National forew
2、ord This British Standard reproduces verbatim ISO 8858-3:2004 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee PTI/16, Solid mineral fuels, which has the responsibility to: A list of organizations represented on this committe
3、e can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility
4、 of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. a
5、id enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This
6、document comprises a front cover, an inside front cover, the ISO title page, pages ii to v, a blank page, pages 1 to 9 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments Referen
7、ce number ISO 8858-3:2004(E)INTERNATIONAL 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 BS ISO 8858-3:2004 ii BS ISO 8858-3:2004 iiiContents Page Foreword iv Introduction v 1 Sco
8、pe 1 2 Normative references . 1 3 Terms 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 port
9、ion . 5 9.2 Preparation 5 9.3 Flotation test 5 10 Presentation of results . 6 11 Test report 7 Bibliography . 9 BS ISO 8858-3:2004 iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing In
10、ternational Standards 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
11、with ISO, also 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 techn
12、ical committees 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
13、 to the possibility 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: Ter
14、minology and performance. 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 vIntroduction The froth flotation of coal has widespread application for the recovery o
15、f 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 coal under a set of specified condi
16、tions 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 certain test conditions to reveal t
17、he 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 the rate at which coal reacts and b
18、y 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 will facilitate the exchange of info
19、rmation 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 float and sinking of coal. Because
20、of the high reproducibility of results, the test represents a reliable means of comparing the flotation response of different samples. BS ISO 8858-3:2004 blank 1Hard coal Froth flotation testing Part 3: Release evaluation 1 Scope This part of ISO 8858 describes a laboratory method for release evalua
21、tion 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 are indispensable for the application of this document. For dated references, onl
22、y 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 preparation ISO 3696:1987, Water for analytical laboratory use Specification and test
23、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 portion of coal is mixed with water to form a suspension in the flotation cell, o
24、r 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 characteristics, the flotation operation is inhibit
25、ed 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 only reagents of recognized analytical grade and the following. 5.1 Water, confor
26、ming to grade 3 of ISO 3696. 5.2 Collector, undiluted n-dodecane. BS ISO 8858-3:2004 2 5.3 Frother. Prepare a solution of 0,1 % (V/V) 4-methylpentan-2-ol (formerly called methyl isobutyl carbinol or MIBC) by diluting 1 ml of MIBC to 1 litre using water (see 5.1). All dosages of MIBC stated refer to
27、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 testing, comprising the following. a) A flotation cell, of capacity approximately 3,5 litres, made from an inert
28、 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 5,7 m/s. The impeller shall be positioned centrally with a clearance of no more than 5 mm from the base of th
29、e 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 flotation cell. 6.3 Constant level device, for maintaining the pulp at a constant level during the test. NOTE The l
30、evel 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 tailings. 6
31、.7 Timing device, accurate to 1 s and capable of being zeroed and started as required. BS ISO 8858-3:2004 3Key 1 drive mechanism 2 cell 3 metal base 4 levelling screws Figure 1 Typical flotation machine BS ISO 8858-3:2004 4 Key 1 cell 2 hood diffuser 3 impeller 4 impeller shaft Figure 2 Detail of fl
32、otation cell and impeller 7 Sampling and preparation of test sample Take a gross sample which is at least five times 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 su
33、pernatant water. Mix the resulting thickened slurry and determine its solids content. The 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
34、tests are prepared in the same manner. Since replicate 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 ISO
35、 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 employed because such practices can affect the flotation characteristics of the coal. BS ISO 8858-3:2004 58 Flotation test conditions 8.1 Test temperature The test tempe
36、rature shall be as specified in ISO 8858-1 and shall be recorded in the test report. 8.2 Impeller operating 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 a
37、pproximately 5,7 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 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
38、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 required from the measured volume of the flotation cell at the pulp level (s
39、ee 8.4) and the moisture content of the test sample (see ISO 8858-1) 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 flotation cell at the pulp level (see 8.4) and the solids content of t
40、he 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 (5.1) and start the impeller with the air inlet valve closed. Gradually add
41、 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 add water to the required level. Agitate for 2 min at the operating impeller
42、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 (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
43、 air. Add the frother (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 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 m
44、in. Close the air valve. BS ISO 8858-3:2004 6 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 Add the combined froth concentrates to the flotati
45、on cell again 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 a dose rate of 20 l/t and condition for an addit
46、ional 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 ls 1per square metre of pulp surface area. Collect froth concentrate 1 in a container for 30 s.
47、Change the container and collect froth concentrate 2 for the following 30 s. b) 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)
48、 Change the container and increase the air flow rate to 1 ls 1per square metre 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
49、 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 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 o
