1、BRITISH STANDARD BS7312:1990 ISO8833:1989 Methods of test for Magnetite for use in coal preparationBS7312:1990 This BritishStandard, having been prepared under the directionof the Solid Mineral Fuels Standards Policy Committee, was published underthe authority of the BoardofBSI and comes intoeffecto
2、n 30June1990 BSI01-2000 The following BSI references relate to the work on this standard: Committee reference SFC/5 Draft for comment86/55462 DC ISBN 0 580 18446 3 Committees responsible for this BritishStandard The preparation of this BritishStandard was entrusted by the Solid Mineral Fuels Standar
3、ds Policy Committee (SFC/-) to Technical Committee SFC/5, upon which the following bodies were represented: Association of British Mining Equipment Companies British Coal Corporation Coal Preparation Plant Association Minerals Engineering Society Amendments issued since publication Amd. No. Date Com
4、mentsBS7312:1990 BSI 01-2000 i Contents Page Committees responsible Inside front cover National foreword ii Introduction 1 1 Scope 1 2 Normative references 1 3 Sampling 2 4 Determination of moisture content 2 5 Treatment of samples prior to laboratory analysis 4 6 Determination of particle size dist
5、ribution 5 7 Determination of total magnetics content 5 8 Determination of relative density 7 9 Determination of total iron content 8 10 Determination of iron(II) content 8 Figure 1 Sampling spear 3 Figure 2 Sampling auger 3 Figure 3 Apparatus for determination of magnetics content 6 Figure 4 Dissol
6、ution/titration apparatus 9 Table 1 Minimum number of bags to be sampled 2 Publications referred to Inside back coverBS7312:1990 ii BSI 01-2000 National foreword This BritishStandard has been prepared under the direction of the Solid Mineral Fuels Standards Policy Committee. It is identical with ISO
7、8833:1989 “Magnetite for use in coal preparation Test methods” prepared by Technical Committee ISO/TC27, Solid mineral fuels, of the International Organization for Standardization (ISO). With reference to clause2 and10.3.5, the relevant requirements in BS1583:1986 “Specification for one-mark pipette
8、s” are equivalent to those in ISO648:1977. With reference to clause2 and6.2, the relevant requirements in BS410:1986 “Specification for test sieves” and BS1796:1976 “Method for test sieving” are equivalent to those in ISO3310-1:1982 and ISO2591:1973. A British Standard does not purport to include al
9、l the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-references International Standard Corresponding BritishStandard ISO2597:1985 BS7020
10、Analysis of iron ores Part4 Methods for the determination of total iron content Section4.1:1988 Titrimetric methods (Identical) ISO3081:1986 BS5660 Methods of sampling iron ores Part1:1987 Manual method of increment sampling (Identical) ISO3083:1986 BS5661:1987 Method for preparation of samples of i
11、ron ores by manual means (Identical) Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to10, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated i
12、n the amendment table on the inside front cover.BS7312:1990 BSI 01-2000 1 Introduction The basic requirements for a material to be used in dense medium suspension are that it should be inert, have a high relative density and be easy to recover. In coal preparation, the mineral magnetite (FeO, Fe 2 O
13、 3 ) has become the most commonly used material, not only because it fulfils all the above criteria, but also because of its worldwide occurrence either as an iron ore or as a by-product of mining operations for other minerals. Like any mineral, magnetite rarely occurs in the pure state and the pres
14、ence of gangue minerals may lower the relative density and affect the ferromagnetic properties. In addition, like other minerals in the spinel group, there may be substitution of either or both the divalent and/or trivalent ions by ions of other metals (e.g.Mg 2+ , Mn 2+ , Al 3+ , Cr 3+ , Mn 3+ ). T
15、hese variations may seriously affect the efficiency of recovery operations and it is important when designing a coal preparation plant that the manufacturer of the magnetic separators be informed of the source of magnetite to be used and if possible be provided with a sample. The purpose of this Int
16、ernational Standard is to provide a basis for the testing of magnetite for use in coal preparation. It is intended for use by contracting parties in the sale and purchase of magnetite and for coal preparation engineers engaged in the design and quality control fields. The tests specified in this Int
17、ernational Standard will assist the user in the selection of magnetite for use in dense medium suspension and provide a basis for quality control testing. No attempt is made to formulate the requirements for particular plant applications. The specified tests should ensure that the properties which m
18、ake magnetite suitable for coal preparation purposes are simply and adequately tested. These properties are a) moisture content; b) particle size distribution; c) total magnetics content; d) relative density; e) total iron content; f) iron(II) content; g) fundamental magnetic properties. All the abo
19、ve tests may be required for the assessment of magnetite from a new source, but for routine checking of regular supplies, moisture, particle size distribution, total magnetics content and relative density should be sufficient. Tests for fundamental magnetic properties are not described because the d
20、etermination of suitable parameters requires very specialized apparatus and techniques and is probably best undertaken by a University or Research Institute whose staff are experienced in making such measurements. There is a lack of consensus as to which magnetic parameters are relevant in the conte
21、xt of this International Standard. Therefore, it is left open for the interested parties to decide which property to measure. However, there is some evidence to suggest that the coercivity is a guide to the ease of recovery of a magnetite and that the saturation magnetic moment is a measure of the p
22、urity of the actual magnetite grains. This International Standard applies exclusively to the testing of magnetite and no attempt is made to recommend specific tests for the dense medium suspensions of which magnetite forms the solid phase. 1 Scope This International Standard specifies methods for th
23、e sampling and testing of magnetite for use in coal preparation. The test methods are intended primarily for the testing of milled magnetite, the largest particle size of which is usually less than2504m. However, the tests are also applicable to unmilled magnetite with an upper particle size limit o
24、f about5004m. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements
25、 based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards listed below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO648:1977, Laboratory glassware One-mark pipettes. ISO2591:1
26、973, Test sieving. ISO2597:1985, Iron ores Determination of total iron content Titrimetric methods. ISO3081:1986, Iron ores Increment sampling Manual method. ISO3083:1986, Iron ores Preparation of samples Manual method. ISO3310-1:1982, Test sieves Technical requirements and testing Part1: Test sieve
27、s of metal wire cloth. BS7312:1990 2 BSI 01-2000 3 Sampling 3.1 General Sampling shall be carried out in accordance with ISO3081, which specifies the procedures for taking samples of iron ores loaded onto and discharged from conveyors, railway wagons, bunkers, ships and stockpiles, by the manual inc
28、rement method, subject to the following provisions. If possible, carry out sampling during material transfer, using a conventional manual increment shovel conforming to the requirements of ISO3081. If sampling during material transfer is impracticable, use sampling spears (seeFigure 1) for sampling
29、bagged materials or small piles, and screw-type augers (seeFigure 2) when sampling from existing stockpiles, wagons, ships,etc., or in situations where the material has compacted. The following procedure shall be used when sampling magnetite contained in sealed bags. a) Select a number of bags in ac
30、cordance with the requirements of Table 1. b) Open the bags and incline them so that the sampling spear can be inserted at an angle close to the horizontal. Insert the spear fully with the slot underneath and rotate the spear through two complete revolutions. c) Rotate again through180 so that the o
31、pen slot is uppermost and withdraw the spear containing the increment. d) Place the increment in a container fitted with an air-tight lid. e) Repeat this procedure until all the requisite bags have been sampled and a total sample mass of approximately1kg is obtained. Table 1 Minimum number of bags t
32、o besampled When screw-type augers are used, the stockpile or loaded material shall be systematically sampled at various depths, including the bottom of the pile if practicable, to ensure representative sampling. 3.2 Preparation of samples The gross sample, subsamples or increments obtained in accor
33、dance with ISO3081 shall be prepared in accordance with ISO3083 subject to the following provisions. a) If it proves difficult to carry out sample division because the sample is too wet, pre-dry the sample sufficiently to overcome this difficulty. If necessary, determine the moisture content before
34、drying. b) If the maximum particle size of the magnetite is such that grinding of the material is necessary in order to comply with the preparation procedures, then take separate samples for moisture determination, size analysis and physical/chemical analysis. The mass of sample for a particular tes
35、t shall be that specified in ISO3083. Magnetite used in coal preparation is usually in a finely divided form. Therefore, it will generally not be necessary to grind the material and it will be sufficient to provide a single sample for all analytical purposes. This sample shall have a mass of not les
36、s than1kg and be stored in an airtight container to ensure that it is protected from any alteration. c) If sampling is for comparative purposes between contracting parties, at least four samples shall be prepared. Three of the samples are intended for the seller, the purchaser and arbitration, and o
37、ne is held in reserve. d) Further sample division to obtain test portions for a particular analytical test shall preferably be carried out using the increment division method specified in ISO3083. Sample division using riffle dividers, or other similar equipment, or random spot sampling may be used
38、provided that these methods can be shown to be free of significant bias. 4 Determination of moisture content 4.1 General The total moisture content of a consignment may be required for both commercial and safe shipment purposes. A knowledge of the total moisture content of samples prepared for labor
39、atory analysis may also be required for subsequent conversion of the analytical results to the dry basis. The total moisture content of a consignment is often required in order to comply with various maritime regulations as, when moisture is present in excess, it may result in stability problems dur
40、ing shipping. Number of bags in batch Minimum number of bags to be sampled 250 All bags 5 1 per50 (to the nearest50 bags)BS7312:1990 BSI 01-2000 3 The total moisture content shall be determined either in one stage or in two stages, where the free moisture and air-dried moisture contents are separate
41、ly determined. This latter method is used when large quantities are involved or if predrying is necessary in order to carry out the sample preparation (see3.2). In both methods the aim is to determine the total moisture content only, but it has been found that loosely-bound sulfur compounds which ma
42、y be present in the magnetite matrix may also be released. In general, errors from this source will be insignificant. The determination shall be carried out on a mass of approximately1kg for a consignment sample and a mass of100g for a sample prepared for laboratory analysis. When a gross sample is
43、taken from a consignment, at least four moisture samples shall be prepared and tested. Where possible, duplicate determinations should be carried out on laboratory analysis samples. 4.2 Apparatus 4.2.1 Drying trays of non-corrodible material NOTEA minimum loading area of9dm 2is recommended for1kg te
44、st portions and of1,5dm 2for100g test portions. 4.2.2 Balances a) A balance capable of weighing up to5kg to an accuracy of 0,1g. b) A balance capable of weighing up to200g to an accuracy of 0,01g. 4.2.3 Laboratory air-oven, capable of being maintained at a temperature in the range105 C to110 C and o
45、f accommodating the drying trays. 4.2.4 Desiccator 4.3 Weighings All weighings described in4.4 and4.5 shall be carried out using the appropriate balance(4.2.2) to an accuracy of 0,1g if a1kg test portion is taken or to an accuracy of 0,01g if a100g test portion is taken. Figure 1 Sampling spear (typ
46、ical dimensions) NOTEVarious diameters and lengths will be needed for specific pile sizes. Figure 2 Sampling augerBS7312:1990 4 BSI 01-2000 4.4 Method1: One-stage method 4.4.1 Test portion Take a test portion of approximately1kg or approximately100g, as appropriate (see4.1 and4.3), from the sample,
47、in accordance with3.2. 4.4.2 Procedure Weigh a clean, dry drying tray(4.2.1) (m 1 ), spread the test portion uniformly onto the tray and reweigh(m 2 ). Place the uncovered tray in the air oven(4.2.3) maintained at a temperature in the range105 C to110 C, and dry to constant mass (m 3 ). Weigh it aft
48、er minimum cooling in the case of a1kg test portion or after allowing the tray and sample to cool in the desiccator(4.2.4) in the case of a100g test portion. 4.4.3 Expression of results The total moisture content of the sample, expressed as a percentage by mass, is calculated from the formula where
49、m 1 is the mass, in grams, of the drying tray; m 2 is the initial mass, in grams, of the drying tray with the test portion; m 3 is the final mass, in grams, of the drying tray with the test portion after oven drying. Report the result to one decimal place. 4.5 Method 2: Two-stage method 4.5.1 Free moisture The mass of the test portion and the test procedure are essentially as laid down for the one-stage method, except that the test portion is allowed to attain constant mass by exposure to air at ambient temperature rather than by drying
