1、BRITISH STANDARD BS 7763:1994 ISO 10753: 1994 Method of assessment of the liability to breakdown in water of materials associated with coal seamsBS7763:1994 This British Standard, having been prepared under the directionof the Solid MineralFuels Standards PolicyCommittee, was publishedunder the auth
2、orityofthe StandardsBoardand comesinto effect on 15June1994 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference SFC/5 Draft for comment 90/52205 DC ISBN 0 580 23160 7 Committees responsible for this British Standard The preparation of this British Standa
3、rd was entrusted by the 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 Low Temperature Coal Distillers Association of Great Britain Ltd. Minerals Engine
4、ering Society Amendments issued since publication Amd. No. Date CommentsBS7763:1994 BSI 10-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative reference 1 3 Principle 1 4 Reagent 1 5 Apparatus 1 6 Sampling and preparation of test sample 3 7 Proce
5、dure 3 8 Expression of results 5 9 Precision 6 10 Test method 6 Annex A (normative) Calculation of settling time 7 Annex B (informative) Example of a suitable format for the test report 7 Figure 1 Typical apparatus for the determination of breakdown characteristics in water 2 Figure 2 Modified Andre
6、asen sedimentation apparatus 3 Figure B.1 Graphical presentation of breakdown results 8 Table 1 Settling time for 10 4m particles 4 List of references Inside back coverBS7763:1994 ii BSI 10-1999 National foreword This British Standard has been prepared under the direction of the Solid Mineral Fuels
7、Standards Policy Committee and is identical with ISO 10753:1994 Coal preparation plant Assessment of the liability to breakdown in water of materials associated with coal seams, published by the International Organization for Standardization (ISO) and in the preparation of which the United Kingdom p
8、layed a full part. Cross-reference The Technical Committee has reviewed the provisions of ISO 3310-1:1990 to which normative reference is made in the text and has decided that they are acceptable for use in conjunction with this standard. A British Standard related to ISO 3310-1:1990 is BS 410:1986
9、Specification for test sieves. Test sieves of nominal size of openings5004m complying with BS410:1986 are technically equivalent to, and may be used in place of, those complying with ISO 3310-1:1990 (see5.3). A British Standard does not purport to include all the necessary provisions of a contract.
10、Users of British Standards are responsible for their 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 8, an inside back cover an
11、d a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS7763:1994 BSI 10-1999 1 Introduction In this International Standard, the materials associated with coal seams are co
12、llectively referred to as “shale”, although they may contain a variety of rocks and minerals. This International Standard describes a method of assessing the liability of these materials to breakdown on agitation with water. Future activity on this subject could involve a method for simulating the b
13、reakdown that is likely to occur, in practice, in different types of coal preparation plants, to generate samples for further testing. The liability of the shale to breakdown is measured by the proportion of the degraded material passing through a test sieve having a nominal size of openings of5004m
14、. The method described in this International Standard also enables the liability of the shale to form slimes to be assessed, by determining the proportion that is below a nominal particle size of104m, using a simplified sedimentation technique. This technique is based on the assumption that, in the
15、size range being examined, all the particles are spherical, have a relative density of2,5, and fall freely through the suspending liquid according to Stokess Law. These conditions are not entirely fulfilled in practice and the particle size is, therefore, referred to as a nominal value. The extent o
16、f breakdown, as measured by this method, will be affected by whether the shale exhibits any self-flocculation. In the described test, distilled water (or the equivalent) is used to avoid possible flocculation of the shale by any soluble salts in the water. The test may be adapted to assess the relat
17、ive tendencies of shales to break down in a particular plant, by using the same water as is used in that plant. However, it is emphasized that the results of such tests, using plant water, have to be treated with caution because the extent of breakdown that will occur in practice is influenced by th
18、e interaction of all the components present during the washing process, including, for example, any accumulation of soluble salts in the circuit, and by other factors, such as the residence time in the plant. The relationship between the proportion of degraded material passing a5004m test sieve and
19、the proportion of slimes provides useful information on the character of the breakdown, and is therefore included in the results that are reported. The amount of breakdown occurring in practice and in the test will be affected by the history of the sample. For this reason, the sample is placed in a
20、sealed container as soon as is practicable after being taken. 1 Scope This International Standard specifies a method for assessing the liability of materials associated with coal seams to breakdown on agitation with water. 2 Normative reference The following standard contains provisions which, throu
21、gh reference in this text, constitute provisions of this International Standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applyin
22、g the most recent edition of the standard indicated below. Members of IECandISO maintain registers of currently valid International Standards. ISO 3310-1:1990, Test sieves Technical requirements and testing Part 1: Test sieves of metal wire cloth. 3 Principle Degradation of a test portion of shale i
23、n the size range5,6mm to2,8mm, by controlled agitation in water. Determination of the proportion of degraded material passing through a5004m sieve, and determination of the proportion of degraded material of nominal top size less than104m by sedimentation. 4 Reagent During the test, use only distill
24、ed water or water of equivalent purity. 5 Apparatus 5.1 Rigid cylindrical jar, of non-corrodible material and of capacity1,0litre 0,1 litre, with an internal height of approximately170mm (internal diameter approximately85mm) and a height/diameter ratio2,0 0,1. The jar shall have a hard lid which can
25、 be secured to form a watertight seal. 5.2 Rotation machine, capable of rotating the jar about a transverse axis at a rotational frequency of40min 1 1min 1(speed of40r/min1r/min). A typical assembly is shown inFigure 1. NOTE 1A suitable drive can be provided by a0,1kW single-phase motor running at1
26、500r/min, geared down to40r/min. 5.3 Test sieve, having nominal size of openings500 4m, complying with ISO3310-1. NOTE 2This sieve is liable to suffer minor distortion when heated to105 C (see7.5), and should therefore be reserved exclusively for use in this test. Furthermore, it is important to ens
27、ure that the sieve is constructed of materials that are stable at the temperature of drying.BS7763:1994 2 BSI 10-1999 5.4 Funnel, into which the5004m test sieve (5.3) will fit. 5.5 Heat-resistant tray, of non-corrodible material, large enough to accommodate the5004m test sieve. 5.6 Container, of cap
28、acity approximately100ml, fitted with a cover. 5.7 Two test sieves, having nominal sizes of openings5,6mm and2,8mm, complying with ISO3310-1. 5.8 Two measuring cylinders, of capacity1 litre each, fitted with stoppers. 5.9 Modified Andreasen sedimentation apparatus, comprising (seeFigure 2) a measuri
29、ng cylinder (A), having a pipette (B) connected to a10ml reservoir (C) via a three-way stopcock (D). The neck of the flask is fitted with a ground-glass stopper (E) which has a small opening (F) to allow air to enter the flask when a sample is withdrawn, by applying suction at point G; an outlet (H)
30、 allows the sample to be run off. The Andreasen sedimentation apparatus is modified by reducing the length of stem of the pipette, so that the sample is withdrawn at the100mm mark. The apparatus shall be protected from all sources of vibration during the test. 5.10 Suction device, capable of applyin
31、g a steady, controlled suction to the sedimentation pipette (5.9). NOTE 3An aspirator is preferred for this purpose. 5.11 Evaporating dish, of nickel or stainless steel, having a diameter of50mm. 5.12 Flask, of capacity at least2litres. 5.13 Thermostatically-controlled bath, capable of being maintai
32、ned at approximately ambient temperature, to within 0,2 C, and of suitable dimensions to contain the sedimentation apparatus(5.9), a measuring cylinder (5.8) and the flask (5.12). The bath shall operate without causing significant vibration or disturbance of the measuring cylinder and its contents,
33、when placed in the bath. NOTE 4If a thermostatically controlled bath is not available, a large container filled with water that has been allowed to attain room temperature may be used instead. Figure 1 Typical apparatus for the determination of breakdown characteristics in waterBS7763:1994 BSI 10-19
34、99 3 5.14 Drying oven, well ventilated and capable of being maintained in the temperature range105 C to110 C. 5.15 Stop clock 5.16 Analytical balance(s), capable of weighing up to20g to the nearest0,000 1g and up to200g to the nearest0,01g. 5.17 Wash bottle, of capacity at least400ml, fitted with a
35、fine spray-jet outlet. 5.18 Desiccator 5.19 Vibration-free bench 6 Sampling and preparation of test sample If sufficient material is available, take a representative sample containing a minimum of1kg in the5,6mm to2,8mm size fraction. If there is insufficient material to provide the required amount
36、in this size fraction, crush all the larger shale and add the5,6mm to2,8mm size fraction of the crushed product to that size fraction in the original material. If neither of these measures provides sufficient material, a size fraction of5,6mm to1,0mm shall be used instead. Full details of the sample
37、 taken shall be included in the test report (see clause10). NOTE 5It may be useful to prepare and test separate representative samples from the floor, roof and dirt bands for each seam. NOTE 6If the test sample is obtained from raw coal by means of float and sink separation, this may affect the resu
38、lts of the test. Remove the dust from the test sample by gentle blowing with air and store the test sample, until required for testing, in a secure, sealed container. 7 Procedure 7.1 Determination of initial moisture content Determine the moisture content of the shale “as received” by weighing a10g
39、portion, to an accuracy of 0,000 1g, drying in the oven (5.14) for2h at105 C to110 C and then reweighing. 7.2 Preparation of test portion Dry for2h in the oven (5.14), at105 C to110 C, enough of the test sample to provide a mass of120g, when dried, and place it in a sealed container. 7.3 Determinati
40、on of residual moisture content Determine the residual moisture in the test portion by taking10g of the dried test sample (see7.2), weighed to an accuracy of 0,000 1g, drying in the oven (5.14) to constant mass at105 C to110 C and then reweighing. 7.4 Agitation of test portion Weigh, to an accuracy
41、of 0,01g, 100g of the dried test sample (7.2), place in the cylindrical jar (5.1) and add500ml of water (clause4). Seal the jar securely, place it in the rotation machine (5.2) and rotate it about a transverse axis (i.e.“end over end”) at a rotational frequency of40min 1 1min 1(speed of40r/min1r/min
42、) for30min. Figure 2 Modified Andreasen sedimentationapparatusBS7763:1994 4 BSI 10-1999 7.5 Sieving of suspension Locate the funnel (5.4) in the neck of one of the measuring cylinders (5.8) and mount the5004m test sieve (5.3) in the funnel. Sieve the suspension resulting from the agitation (7.4) thr
43、ough the test sieve, taking care to ensure that the solids are distributed evenly over the surface of the sieve. Use250ml of water (clause4) to rinse out the jar and wash the residue on the sieve, applying the water by means of the wash bottle (5.17). Remove the sieve from the funnel, place it on th
44、e tray (5.5) and dry in the oven (5.14) at105 C to110 C for1h. Remove the tray containing the sieve from the oven. Brush off the dried material into the tared container (5.6) and dry in the oven to constant mass (see note7). Cool in the desiccator(5.18), to prevent absorption of moisture, and weigh
45、to an accuracy of 0,01g. NOTE 7If the operation of drying to constant mass is likely to take more than30min, the mass measured at that time should be recorded and used to calculate the concentration of solids in the suspension passing through the sieve (see7.8). This procedure is used in order that
46、the proportion of material that is below a nominal particle size of104m may be determined with the minimum of delay. 7.6 Treatment of fines While the material retained on the sieve is being dried, rinse any fine particles adhering to the funnel into the measuring cylinder containing the suspension t
47、hat has passed through the sieve, using100ml of water (clause4). Dilute to1litre and place the measuring cylinder in the thermostatically-controlled bath (5.13). 7.7 Preparation of water and apparatus for sedimentation Fill the flask (5.12) with water (clause4) and place it, together with the sedime
48、ntation apparatus (5.9), in the thermostatically-controlled bath (5.13), maintained, to within 0,2 C, at a temperature close to ambient temperature. Allow at least1h to reach temperature equilibrium before proceeding with the procedure described in7.8. Use this water whenever water is required for s
49、ubsequent steps in the procedure. 7.8 Adjustment of concentration of suspension Calculate the percentage of material passing through the 5004m test sieve in accordance with8.1, using the approximate mass of material retained on the sieve if necessary (see note7). From this percentage, and the mass of the test portion (see7.4), determine the concentration of solids in the suspension obtained as described in7.6. If this concentration does not exceed20g/l, use the suspension directly for the sedimentation (see7.10). Otherwise, invert
