BS 7530-1-1992 Methods for froth flotation testing of hard coal - Laboratory procedure《硬煤泡沫浮选试验方法 实验室规程》.pdf

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1、BRITISH STANDARD BS 7530-1: 1992 Methods for Froth flotation testing of hard coal Part 1: Laboratory procedureBS7530-1:1992 This British Standard, having been prepared under the directionof the Solid Mineral Fuels Standards Policy Committee, was published underthe authority of the Standards Board an

2、d comes intoeffect on 31January1992 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference SFC/5 Draft for comment 87/51450 DC ISBN 0 580 20174 0 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the

3、Solid Mineral Fuels Standards Policy Committee (SFC/-) to Technical Committee SFC/5, upon which the following bodies were represented: British Coal Corporation Coal Preparation Plant Association Minerals Engineering Society Amendments issued since publication Amd. No. Date CommentsBS7530-1:1992 BSI

4、10-1999 i Contents Page Committees responsible Inside front cover Foreword ii 0 Introduction 1 1 Scope 1 2 Definitions 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Sampling and preparation of test sample 3 7 Preliminary tests 3 8 Flotation test conditions 3 9 Procedure 3 10 Expression of results 4 1

5、1 Precision 5 12 Test report 5 Appendix A Recommended layout of a form for a test report 6 Figure 1 Typical flotation machine 2 Figure 2 Detail of flotation cell and impeller 2 Publication(s) referred to Inside back coverBS7530-1:1992 ii BSI 10-1999 Foreword This Part of BS7530 has been prepared und

6、er the direction of the Solid Mineral Fuels Standards Policy Committee. Part 2 of the standard will specify a method of evaluating flotation response. This Part is related to ISO8858-1:1990, published by the International Organization for Standardization (ISO). The principal difference is that the a

7、pparatus and procedure are described in more general terms in this standard and are not based on a particular design of apparatus, as is the case in ISO8858-1. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for th

8、eir 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 inside front cover, pages i and ii, pages 1 to 6, an inside back cover and a back cover. This standard has been updated (s

9、ee copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS7530-1:1992 BSI 10-1999 1 0 Introduction The froth flotation of coal has widespread application for the concentration of fine coal particles and their separation fro

10、m mineral matter. The response of coal to the froth flotation process is measured initially by a laboratory-scale test. Although the principles on which such laboratory tests are based are generally similar, the type of equipment and the techniques used vary considerably. The purpose of this Part of

11、 BS7530 is to provide a standard method of test by which preliminary comparisons of the froth flotation characteristics of different coals can be made. Such comparisons are particularly important for exploration programmes. This Part of BS7530 also serves as an introduction for operators who are not

12、 familiar with the techniques (and problems) associated with the froth flotation of coals in the laboratory. The method described 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 flotation po

13、tential of that coal. The flotation characteristics of coals are sensitive to changes in flotation conditions. These conditions can be changed by varying such basic parameters as flotation time, particle size distribution of the feed, reagent and reagent dosage. Separate flotation tests are required

14、 to assess the effect of varying these parameters to determine the best flotation conditions for a particular coal. 1 Scope This Part of BS7530 describes a method for the froth flotation testing of a fine coal, of particle size less than0.5mm, in the laboratory. It is applicable to coal in powder fo

15、rm or in the form of a slurry. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this Part of BS7530, the definitions given in BS3552 apply. 3 Principle A test portion of coal is mixed with water to form a suspensio

16、n in the flotation cell, or a test portion of a slurry is added to the cell and diluted. A flotation agent is added, the suspension is conditioned, and then air is introduced to the cell while agitation is maintained by means of an impeller. The concentrate and the tailings are collected separately

17、and the yield and ash are determined for each. 4 Reagents 4.1 General. During the test, use only reagents of recognized analytical grade and only water complying with grade3 of BS3978. 4.2 Flotation agent. Prepare a mixture of80%(V/V) of n-dodecane and20% (V/V) of4-methylpentan-2-ol. NOTEA stock sol

18、ution of this mixture may be kept for use in several tests. 5 Apparatus 5.1 Flotation machine. A mechanical impeller-type flotation machine, designed for laboratory-scale flotation testing, comprising the following. a) A flotation cell, of capacity2.5L to10L, made from an inert material such as stai

19、nless steel, glass or perspex. b) An impeller assembly, capable of being driven so that the periphery of the impeller moves at a speed of5.7m/s. The impeller shall be positioned centrally with a clearance of6 1mm above the bottom of the cell. c) A means of supplying air to the impeller. A typical fl

20、otation machine is shown inFigure 1 andFigure 2. 5.2 Constant level control, for maintaining the pulp at a constant level in the flotation cell during the test. NOTEAlternatively, the level may be kept constant by the manual addition of water. 5.3 Two scrapers, for removing the froth from the entire

21、 surface of the pulp. 5.4 Graduated micro-pipette or micro-syringe, for adding the flotation agent. 5.5 Timing device, accurate to1s and capable of being zeroed and started as required. 5.6 Balance, capable of weighing to the nearest0.1g. 5.7 Oven, capable of maintaining a temperature within the ran

22、ge105 C to110 C. 5.8 Set of test sieves, complying with BS410, for carrying out a size analysis of the test sample.BS7530-1:1992 2 BSI 10-1999 Figure 1 Typical flotation machine Figure 2 Detail of flotation cell and impellerBS7530-1:1992 BSI 10-1999 3 6 Sampling and preparation of test sample Take a

23、 gross sample which is at least five times the mass required for a single flotation test (see9.1). If the gross sample is in powder form, take representative subsamples for carrying out preliminary tests (see7.2 to7.4). If the gross sample is in the form of a slurry, allow it to settle for at least1

24、2h and then decant the supernatant water. Thoroughly mix the thickened slurry and take representative subsamples for the determination of its solids content and other tests (seeclause7). NOTE 1The history and method of preparation of the samples can affect the flotation characteristics of the coal.

25、The origin 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, care should be taken in the mixing and subdivision of the

26、 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 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 flotati

27、on characteristics of the coal. 7 Preliminary tests 7.1 Determination of solids content of a thickened slurry Take a subsample of about500mL of the thickened slurry (seeclause6) and weigh it, to the nearest0.1g, using the balance(5.6). Dry the slurry in the oven(5.7) at105 C to110 C until the differ

28、ence between successive weighings, at an interval of at least15min drying time, does not exceed0.1g. NOTE 1Drying in the oven for24h is usually adequate. NOTE 2The thickened slurry may be flocculated and filtered first, prior to drying in the oven, provided that all the solids are recovered. Weigh t

29、he dried solids, to the nearest0.1g, and calculate the solids content of the thickened slurry as a percentage by mass. 7.2 Size analysis Carry out a full size analysis of a subsample (seeclause6) by the wet sieving method described in BS1016-17, using the test sieves(5.8). 7.3 Determination of moist

30、ure content If the test sample is in powder form, determine its moisture content by the method described in BS1016-104.1. Also determine the moisture content of each of the size fractions (see7.2), so that results can be calculated on a dry basis. 7.4 Determination of ash Determine the ash of the te

31、st sample and of each of the size fractions (see7.2) by the method described in BS1016-104.4. 8 Flotation test conditions NOTESome coals may not react under the flotation conditions specified in this standard. This does not necessarily mean that the coal is not amenable to froth flotation. In such a

32、 case further experimental work would be necessary to determine suitable flotation conditions. 8.1 Test temperature The test temperature shall be20 10 C. 8.2 Solids content of the pulp The pulp in the flotation cell shall contain100 5g/L of solids, on a dry basis. 8.3 Pulp level The level of the pul

33、p shall be20 2mm below the overflow lip of the flotation cell when the impeller is rotating at the operating speed and the air valve is closed. 8.4 Volume of flotation agent The volume of flotation agent added to the pulp shall be1mL/kg of dry solids (see8.2). 8.5 Air flow rate The air flow rate sha

34、ll be120 12L/min per square metre of surface area of the pulp. NOTEIt is recommended that the air flow be controlled by means of a needle valve coupled to a flowmeter and that a separate on/off valve be provided. 9 Procedure 9.1 Test portion If the test sample is in powder form, calculate the mass o

35、f test portion required from the measured volume of the flotation cell (5.1), the moisture content of the test sample (see7.3) and the specified solids content of the pulp (see8.2). In the case of a slurry, calculate the required mass of thickened slurry from the volume of the flotation cell, the so

36、lids content of the slurry (see7.1) and the specified solids content of the pulp (see8.2). Weigh the test portion, to the nearest0.1g, using the balance(5.6). 9.2 Flotation test If the test portion (see9.1) is in powder form, half-fill the flotation cell(5.1) with water and start the impeller rotati

37、ng at its operating speed, so that the periphery of the impeller moves at5.7m/s, with the air inlet closed. Gradually add the test portion to the flotation cell and top up with water to the required level(see8.3). Continue mixing for10min.BS7530-1:1992 4 BSI 10-1999 If the test portion is a thickene

38、d slurry, transfer it to the flotation cell and add water to the required level. With the air inlet closed, start the impeller rotating at its operating speed and mix the pulp for2min. Add the required volume(see8.4) of the flotation agent(4.2), by means of the micro-pipette or micro-syringe(5.4), b

39、eneath the surface of the pulp and start the timing device(5.5). Condition for1min with the air inlet closed. Open the air inlet and pass air through the flotation cell at the required rate (see8.5). Every5s, move the scrapers(5.3) at a steady rate across the surface of the pulp and collect the frot

40、h, ensuring that none of the pulp is collected with it. NOTE 1As flotation progresses, the frequency of froth removal may be reduced. NOTE 2A significant amount of floated coal may adhere to the sides of the flotation cell above the level of the pulp. This coal should be washed on to the surface of

41、the pulp, using a minimal amount of water, so that it can be removed by the scrapers. Maintain the pulp at the required level manually or by means of the constant level control(5.2). Collect the total froth produced over a flotation period of3min and then stop the impeller. Remove any particles adhe

42、ring to the sides of the cell and the impeller standpipe with a small brush and wash them into the concentrate of coal particles collected with the froth. Remove any particles remaining on the surface of the pulp by means of the scrapers and add them to the concentrate. Then wash any material remain

43、ing on the scrapers or on the cell lip into the concentrate with water. Collect the pulp as the tailings and wash any material remaining on the impeller into the tailings. Dewater and dry the concentrate and the tailings separately. Weigh the concentrate and the tailings, to the nearest0.1g, using t

44、he balance(5.6) and repeat the operations of drying and weighing until the difference between successive weighings, at an interval of at least15min drying time, does not exceed0.1g. Record the final mass, to the nearest0.1g, in each case. NOTE 3Flocculants may be added as a filtration aid, provided

45、that the products are not required for additional flotation tests. In general, flocculants have an adverse effect on flotation. NOTE 4Drying in an oven should be avoided if caking tests, cooking tests or certain other special tests are to be carried out subsequently, or if the products are prone to

46、excessive oxidation. In these cases, the material should be air-dried and the moisture content of the air-dried product should be determined by the method described inBS1016-104.1 so that its mass can be calculated on a dry basis. Determine the ash of both the concentrate and the tailings by the met

47、hod described in BS1016-104.4. NOTE 5Other properties of the concentrate and tailings may be determined as required. 9.3 Validity of the test For a flotation test to be valid, the sum of the mass of the concentrate and the mass of the tailings, both on a dry basis, should not differ by more than3% (

48、m/m) from the original mass of solids in the test portion, also on a dry basis. Otherwise, disregard the results and carry out a further test. 9.4 Number of tests Repeat the procedure described in9.2 at least once, using a further test portion. 10 Expression of results 10.1 Preliminary tests Report

49、the results of the size analysis (see7.2) as the percentage by mass of each size fraction, calculated on a dry basis, using the moisture contents determined as described in7.3. For calculation of results on a dry basis see BS1016-16. Report the ash of the test sample and of each size fraction (see7.4) as percentages by mass on a dry basis. 10.2 Flotation test Calculate the amount of coal reporting to the concentrate (i.e.the yield) as a percentage by mass, from the following formula where Calculate the amount of material reporting to the tailings, as a percent