ISO 8858-2-2004 Hard coal - Froth flotation testing - Part 2 Sequential evaluation《硬煤 泡沫浮选试验 第2部分 顺序评估》.pdf

1、 Reference number ISO 8858-2:2004(E) ISO 2004INTERNATIONAL STANDARD ISO 8858-2 First edition 2004-08-15 Hard coal Froth flotation testing Part 2: Sequential evaluation Houille Essais de flottation Partie 2: valuation squentielle ISO 8858-2:2004(E) PDF disclaimer This PDF file may contain embedded ty

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6、tale 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 8858-2:2004(E) ISO 2004 All rights reserved iiiContents Page Foreword iv Introduction v 1 Scope 1 2 Normative references. 1 3 Ter

7、ms and definitions. 1 4 Principle. 2 5 Sample 2 6 Apparatus. 2 7 Flotation conditions 2 7.1 Collector dosage. 2 7.2 Frother dosage 3 7.3 Solids content. 3 7.4 Air flow rate . 3 7.5 Test temperature. 3 8 Procedure. 3 8.1 Initial procedure 3 8.2 Initial separation 3 8.3 Subsequent separations 3 8.4 An

8、alysis of concentrate and tailings 4 9 Calculation of results 4 10 Test report 5 Annex A (informative) Worked example of calculation of results . 6 Annex B (informative) Presentation of results 11 ISO 8858-2:2004(E) iv ISO 2004 All rights reservedForeword ISO (the International Organization for Stan

9、dardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International 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

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12、International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn 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 88

13、58-2 was prepared by Technical Committee ISO/TC 27, Solid mineral fuels, Subcommittee SC 1, Coal preparation: Terminology 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 P

14、art 3: Release evaluation ISO 8858-2:2004(E) ISO 2004 All rights reserved vIntroduction The froth flotation of coal has a widespread 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

15、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 conditions and will not necessarily indicate the full potential of that coal. It is accepted that variation of the many parameters in the frot

16、h flotation process can be used to effect the beneficiation of the product. This part of ISO 8858 describes a procedure for the more complete determination of the flotation characteristics of a coal, using the apparatus and basic procedures described in ISO 8858-1. The purpose of this extended proce

17、dure is to provide information similar to that provided by the sink/float curve, which is the basis for density separations. The data obtained are expressed as a yield/ash curve. The information can be used to define the limitations on the cleaning of fine coal by froth flotation. The procedures spe

18、cified in this part of ISO 8858 are of practical significance in the development and evaluation of coal-preparation-plant flotation circuits, although engineering design aspects, such as flotation kinetics and the selection of size and type of cell, are not addressed. The flotation response curve (y

19、ield/ash) indicates the maximum possible yield at any specified ash content. The general shape of the curve indicates the sensitivity of flotation performance to the nature of the coal and to operating conditions. The procedure may be modified to test and compare the performance of different frother

20、 and collector types, the assessment of liberation by grinding, and the comparison of alternative feed size ranges. However, results of such tests should clearly indicate any use of non-standard procedures. INTERNATIONAL STANDARD ISO 8858-2:2004(E) ISO 2004 All rights reserved 1Hard coal Froth flota

21、tion testing Part 2: Sequential evaluation 1 Scope This part of ISO 8858 sets out a laboratory sequential procedure for the froth flotation testing of fine coal, e.g. coal having a particle size of less than 0,5 mm. The procedure provides a means of evaluating for a coal the flotation characteristic

22、s (expressed as a yield/ash relationship) that may be expected from the froth flotation process. Pulp samples that cannot be dewatered without the use of heat or chemical additives are not covered by this part of ISO 8858; nor does it cover procedures for the investigation of flotation kinetics. The

23、 test is not intended to provide plant design data. This part of ISO 8858 should be read in conjunction with ISO 8858-1. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated

24、 references, the latest edition of the referenced document (including any amendments) applies. ISO 589:2003, Hard coal Determination of total moisture ISO 1171:1997, Solid mineral fuels Determination of ash ISO 1213-1:1993, Solid mineral fuels Vocabulary Part 1: Terms relating to coal preparation IS

25、O 1953:1994, Hard coal Size analysis by sieving ISO 7936:1992, Hard coal Determination and presentation of float and sink characteristics General directions for apparatus and procedures ISO 8858-1:1990, Hard coal Froth flotation testing Part 1: Laboratory procedure ISO 13909-4: 2001, Hard coal and c

26、oke Mechanical sampling Part 4: Coal Preparation of test samples 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 1213-1 and the following apply. ISO 8858-2:2004(E) 2 ISO 2004 All rights reserved3.1 higher rank coal coal having a gross specific energy

27、 of 21,00 MJ/kg or greater on an ash-free, moist (afm) basis and 27,00 MJ/kg or greater on a dry, ash-free (daf) basis 4 Principle A sequence of laboratory flotation tests is carried out on a single coal sample, using a procedure based on that described in ISO 8858-1. Variations on that procedure ar

28、e made to generate a number of products, by refloating concentrates and tailings a number of times. The masses and ash percentages of the various products are used to construct a yield/ash curve showing the flotation response. 5 Sample The history and method of preparation of samples can affect the

29、flotation characteristics of the coal considerably. The history of the sample should be recorded, and care should be taken to ensure that samples for comparison purposes are prepared in a similar manner and, where applicable, in accordance with the sample preparation procedures specified in ISO 1390

30、9-4. A size analysis of the sample shall be carried out in accordance with ISO 1953. 6 Apparatus The apparatus shall be as specified in ISO 8858-1. 7 Flotation conditions 7.1 Collector dosage To establish well-defined flotation response curves, it is necessary to extend the range of conditions speci

31、fied in ISO 8858-1. Different coals will require different conditions to display the attainable range of yields and corresponding product ash levels. To obtain a preliminary guide to the appropriate flotation conditions for this extended test, it is recommended that a sample of the coal be first tes

32、ted according to the procedure specified in ISO 8858-1. NOTE It is suggested that the collector increments referred to in 8.3 be selected on the basis of the result of the ISO 8858-1 test in Table 1. Table 1 ISO 8858-1 yield % ISO 8858-1 suggested collector dosage (fraction of dosage used in ISO 885

33、8-1) 80 As in ISO 8858-1 = 1 ml/kg 25 % = 0,25 ml/kg 10 % = 0,10 ml/kg 2,5 % = 0,025 ml/kg The final result is largely independent of the selected increment size. Experienced operators may prefer to use other dosage rates. ISO 8858-2:2004(E) ISO 2004 All rights reserved 37.2 Frother dosage Frother a

34、ddition at each stage may be made at approximately half the dosage specified in ISO 8858-1, i.e. at 0,05 ml of 4-methyl-2-pentanol (formerly called methyl isobutyl carbinol MIBC) (50 ml of 0,1 % aqueous solution) per kilogram of dry solids in the initial sample. NOTE Frother dosages are not critical

35、 beyond the initial separation. Operator judgment may be used to maintain an adequate froth. 7.3 Solids content The solids content for the first flotation stage shall be as specified in ISO 8858-1. For all subsequent stages, the mass of solids shall be that which results from the previous flotation

36、stage. 7.4 Air flow rate The air flow rate shall be as specified in ISO 8858-1. 7.5 Test temperature The test temperature shall be as specified in ISO 8858-1 and shall be reported with the test results. 8 Procedure 8.1 Initial procedure The moisture content, size analysis and other parameters specif

37、ied in ISO 8858-1 shall be determined. 8.2 Initial separation The initial separation shall be carried out generally following the principles given in ISO 8858-1 with the exceptions that a) no collector shall be used, b) no conditioning time is required, and c) no frother shall be used. Both concentr

38、ate and tailings shall be retained as pulps for subsequent reflotation. NOTE Experience has shown that omission of frother and collector permits selective recovery of low-ash rapid floating particles and better definition of the low-yield end of the curve. To ensure that the cell volume for subseque

39、nt tests is not exceeded, care should be taken to use a minimum of wash water in collecting the two products. 8.3 Subsequent separations After performing an initial flotation, the resultant tailings shall be successively refloated, generally following the procedure given in ISO 8858-1, with incremen

40、tal collector addition to recover any floatable particles that may not have been collected with the concentrate. This process shall be continued until it is estimated that reflotation of the successive tailings fraction has resulted in nil or negligible concentrate mass (approxately less than 5 % of

41、 the initial feed sample mass). ISO 8858-2:2004(E) 4 ISO 2004 All rights reservedEach concentrate fraction, resulting from these successive tailings flotations, shall then be refloated as many times as necessary, until further flotation does not result in additional removal of mineral matter (as jud

42、ged by the presence of solids in the tailings), or the concentrate sample to be floated shall have nil or negligible mass (approxately less than 5 % of the initial feed sample mass). After completion of these flotations, each concentrate shall be repeatedly refloated until all entrained mineral matt

43、er is removed. Each tailings fraction resulting from refloating of the concentrates shall then be subjected to further flotations until nil or negligible concentrate is produced. Essentially, the initial feed mass is fractionated by successive reflotations without subsequent recombination of individ

44、ual concentrate or tailings fractions. NOTE 1 It will be rare for any branch of the process sequence to require more than four flotation operations. Usually two or three stages will suffice. NOTE 2 For some coals, further testing may be required to achieve separations yielding down to 2 % of the ini

45、tial feed mass. 8.4 Analysis of concentrate and tailings All products may be filtered. All products shall be air-dried, weighed and analysed for moisture and ash as specified in ISO 589 and ISO 1171 respectively, and reported on a dry basis. NOTE Drying in an air oven at 40 C may be carried out, pro

46、vided that equilibration with ambient conditions is achieved before weighing. 9 Calculation of results The mass of reconstituted feed (m R ), in grams, shall be calculated on a dry basis from the following equation: () () RCT 11 NM ij ij mmm = =+ (1) where N is the total number of concentrates; (m C

47、 ) iis the mass of concentrate i, in grams; M is the total number of tailings; (m T ) jis the mass of tailing j, in grams. The percentage mass distribution (D) for a product is given by the following equations: Percentage mass distribution for concentrate i, D i= 100(m C ) i /m R(2) Percentage mass

48、distribution for tailings j, D j= 100(m T ) j /m R(3) The distribution for all products (concentrate and tailings) and the ash percentage of each product shall be determined and the results listed in a single table in ascending order of percentage of ash. Progressive cumulative distribution (i.e. yi

49、eld) and corresponding cumulative ash percentage values shall then be calculated according to the following equations: ISO 8858-2:2004(E) ISO 2004 All rights reserved 5Cumulative percentage yield (Y cum,n ) in the first n products, cum,= 1= N nk k YD (4) where D kis the distribution to the kth product in the ordered list Cumulative percentage of ash (A cum,n ) of the first n products, cum, cum,= 1 ( )= N kk n n k D A A Y (5) where A kis the ash percentage on a dry basis of the kth product in the