BS 8439-2005 Continuous handling equipment and systems - Guide to properties of powders and bulk materials《持续搬运设备和系统 粉末和散装物料特性的指南》.pdf

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1、BRITISH STANDARD BS 8439:2005 Continuous handling equipment and systems Guide to properties of powders and bulk materials ICS 53.040.01 BS 8439:2005 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 13 May 2005 BSI 13 May 2005 The following BSI

2、 references relate to the work on this British Standard: Committee reference MHE/9 Draft for comment 04/30080772 DC ISBN 0 580 45875 X Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee MHE/9, Continuous mechanical handling

3、equipment, upon which the following bodies were represented: Association of Consulting Engineers Automated Material Handling Systems Association Health and Safety Executive Materials Handling Engineers Association Minerals Engineering Society Quarry Products Association Solids Handling and Processin

4、g Association Co-opted Members Amendments issued since publication Amd. No. Date Text affectedBS 8439:2005 BSI 13 May 2005 i Contents Page Committees responsible Inside front cover Foreword ii Introduction 1 1S c o p e 1 2 Normative references 1 3 Terms, definitions, symbols and abbreviations 2 4 Ge

5、neral 3 5 Characteristics 3 6 Mechanical strength 9 7 Contact with other surfaces 18 8 Particle properties 19 9 Pneumatic handling 22 Bibliography 26 Figure 1 Typical particle size histogram 4 Figure 2 Typical particle size distribution 5 Figure 3 Moisture contents of a range of sieved size fraction

6、s taken from a single sample of coal 8 Figure 4 Apparatus for measurement of angle of repose 10 Figure 5 Coulomb failure criterion 11 Figure 6 Effective angle of internal friction and unconfined yield stress 12 Figure 7 Jenike split ring shear cell apparatus 12 Figure 8 Shear stress dependency on mo

7、isture content for a typical fine coal 13 Figure 9 Typical shear cell test observations 14 Figure 10 Hvorslevs failure surface 15 Figure 11 Effect of time storage on yield loci 16 Figure 12 Typical flow functions 17 Figure 13 Tensile stress and its relation to other stress parameters 18 Figure 14 Sh

8、ear cell wall friction test apparatus 19 Figure 15 Relationship between hardness scales 20 Figure 16 Permeameter 23 Figure 17 Fluidization properties 24 Figure 18 Geldart fluidization classification 25 Table 1 Useful range of particle size measuring methods 5 Table 2 Recommended minimum quantity of

9、granular solids to be sieved based on maximum particle size 6BS 8439:2005 ii BSI 13 May 2005 Foreword This British Standard has been prepared by Technical Committee MHE/9. The handling, transport and storage of powders and bulk materials represent a large proportion of all industrial activities beca

10、use of the diversity of the materials involved, the methods in which they are handled and transported, and the sectors of industry which utilize them. Therefore an exact knowledge of powders and bulk materials is necessary for the specification of handling and transport systems. Because of their ext

11、remely varied origins, nature, granular characteristics, processing, etc, powders and bulk materials have very diverse physical characteristics, some of which (for example granulometry, particle shape, particle density) can be described and measured in a precise way, under conditions which are deter

12、mined and constant, while others (for example angle of internal friction, cohesion) are affected by: a) changes in environmental conditions, for example moisture, storage time and temperature; b) the mode of movement of the material, for example mechanical handling, gravity flow and pneumatic handli

13、ng. This document is comprised of two key areas which take account of these related features. Specific properties of powders and bulk materials with regard to their descriptions. Underlying principle and methods of measuring these properties. This publication does not purport to include all the nece

14、ssary 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. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 27 and a back cov

15、er. The BSI copyright notice displayed in this document indicates when the document was last issued.BS 8439:2005 BSI 13 May 2005 1 Introduction Equipment for handling, transporting and storing powders and bulk materials is most likely to operate satisfactorily if the properties of the materials are

16、known and utilized when the equipment is designed and selected. This British Standard is intended to help in the equipment design and selection process by detailing the most important of these properties and appropriate tests by which they can be measured. The first step in any investigation into th

17、e properties of a powder or bulk material is to determine if it is a single component material or a mixture. The results of material property testing cannot be representative of the material if the sample is inappropriate. Standard test procedures might give guidance on: a) sampling and sample prepa

18、ration procedures; b) replicate testing. With regard to the design of mechanical, gravity flow and pneumatic handling systems, the most important properties of powders or bulk materials are considered to be: 1) bulk density; 2) particle size distribution; 3) moisture content and moisture/strength re

19、lationship; 4) abrasiveness; 5) angle of slide on chutes; 6) angle of repose; 7) minimum fluidization velocity. To avoid costly errors, such information is necessary at the conceptual design stage of a materials handling scheme because final geometric design details of a materials handling plant are

20、 usually fixed at this time. 1 Scope This British Standard describes the properties of powders and bulk materials that are commonly used when designing continuous handling equipment systems for powders and bulk materials. The standard gives guidance on methods and procedures for the determination of

21、 these characteristics. This standard does not describe the following properties: a) combustibility; b) electrical properties; c) explosibility; d) flammability; e) thermal properties; f) hygiene; g) toxicity. NOTE For information on items a) to e) attention is drawn to The Equipment and Protective

22、Systems Intended for Use in Potentially Explosive Atmospheres (Amendment) Regulations 2001 1. This standard is not applicable to the following categories of materials: 1) materials that do not behave as powders or bulk materials (for example cakes, sludges, saturated and drained materials, slurries)

23、; 2) frozen materials; 3) chemically reactive materials (for example which solidify on exposure to air) unless an inert atmosphere can be maintained; 4) fibrous or stringy materials whose particles interlock. 2 Normative references The following referenced documents are indispensable for the applica

24、tion of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. BS 410-1, Specification for test sieves Part 1: Test sieves of metal wire cloth.BS 8439:2005 2 BSI 13 May 2005 3 Term

25、s, definitions, symbols and abbreviations 3.1 Terms and definitions For the purposes of this British Standard, the following terms and definitions apply. 3.1.1 particulate solid material in the form of many discrete and independent particles 3.1.2 granular solid material in the form of many discrete

26、 and independent particles which are so large that interstitial air plays a small role in determining the pressures and flow of large masses of the solid 3.1.3 free flowing granular solid granular solid whose flowing behaviour is not significantly affected by cohesion 3.1.4 fines material in the for

27、m of many discrete and independent particles having a particle size 100 % less than 850 m (see Jenike 2) 3.1.5 powder material in the form of many discrete and independent particles having a mean particle size less than 0.05 mm 3.1.6 dust material in the form of many discrete and independent particl

28、es having a particle size less than 75 m 3.2 Symbols and abbreviations For the purposes of this British Standard, the following symbols and abbreviations apply. C Permeability factor c Cohesion e Porosity FF Flow function f c Unconfined yield stress L Bed length M Mass m Moisture content T Tension t

29、 Time in days U Gas velocity U mf Minimum fluidization velocity p Pressure drop Bulk density Effective angle of internal friction c Angle of slide on chutes Coefficient of wall friction i Angle of internal friction e Effective angle of internal friction (alternative notation) r Angle of reposeBS 843

30、9:2005 BSI 13 May 2005 3 4 General The powder or bulk material may be identified by its trade name, its common name or its chemical formula. The name should describe the powder or bulk material as precisely as possible, for example in place of the general term “flour”, the identification might inclu

31、de information about the grain from which it was produced such as oats, rye or wheat etc. Where appropriate, the chemical composition should also be given. This is especially important where knowledge of the constituents might affect safety or environmental issues. Further information is given in th

32、e Report of the EFCE 3 and ASTM D 6128 4. NOTE Attention is drawn to The Control of Substances Hazardous to Health Regulations 2002 (COSHH) 5 regarding the handling of powders and bulk materials. A specific property might not have a unique value but might fall within specified bounds of variability.

33、 5 Characteristics 5.1 Particle size and shape 5.1.1 General Powders and bulk materials consist of large numbers of particles usually of different sizes. For a mass of mono-sized spherical particles, the particle size can be described by a single dimension, the particle diameter. For non-spherical p

34、articles additional information on particle shape is required to characterize the particle. For predominantly coarse materials such as mineral aggregates, sands and fillers the following classifications are used (see Wilkinson et al. 6): a) rounded; b) irregular; c) angular; d) flaky; e) elongated;

35、f) flaky and elongated. For powders having a maximum dimension of 1 000 m, BS 2955 gives definitions of the following terms: 1) acicular; 2) angular; 3) crystalline; 4) dendritic; 5) fibrous; 6) flaky; 7) granular; 8) irregular; 9) nodular; 10) spherical. t Tangent angle of internal friction w Angle

36、 of wall friction Particle density m Major consolidating stress t Tensile stressBS 8439:2005 4 BSI 13 May 2005 5.1.2 Measuring methods There are many methods of determining the particle size of a powder or bulk material. Three commonly used methods are as follows: a) sieving (or screening); b) sedim

37、entation/elutriation; c) microscopy. These methods are described in BS 1796-1, BS 3625 and BS ISO 13317. 5.2 Particle size distribution 5.2.1 General A particle size distribution is one possible outcome of submitting a representative sample of powder or bulk material to particle size analysis. It re

38、lates the distribution of the particle size fractions that comprise the sample. For materials that are not mono-sized, two methods of presenting the data are commonly used. The first is a histogram relating the percentage between certain particle sizes, on a mass basis, as shown in Figure 1. The oth

39、er method of presenting the particle size distribution is by a cumulative percentage frequency graph as shown in Figure 2. If a fully detailed size analysis is not available, sufficient points on the graph should be given, designated d x , where d is the particle size below which there is x % less t

40、han by mass. The percentages preferred to provide an adequate distribution are d 10 , d 50and d 90together with the largest particle size. Whered 10is the particle size at which there is 10 % less than by mass;d 50is the particle size at which there is 50 % less than by mass;d 90is the particle size

41、 at which there is 90 % less than by mass. Figure 1 Typical particle size histogram Mass between sieve sizes (Kg) Sieve dimension (particle size)( mm)BS 8439:2005 BSI 13 May 2005 5 5.2.2 Measuring methods There are many methods of determining the particle size distribution of a powder or bulk materi

42、al. Three commonly used methods are as follows: a) sieving (or screening); b) sedimentation/elutriation; c) microscopy. These methods are described in BS 1796-1, BS 3625 and BS ISO 13317. The approximate useful range of each method is indicated in Table 1. Table 1 Useful range of particle size measu

43、ring methods 5.2.3 Representative sampling for granular materials For dry and wet sieving, an adequate quantity of powder or bulk material should be sized to obtain a representative size analysis. Table 2 gives the minimum quantities of powder or bulk material required for results of accuracies spec

44、ified in BS ISO 13909-3. NOTE The recommended quantities given in BS ISO 13909-3 for coal may be taken as a guide for other materials if account is taken of the bulk density which for coal is 800 kg/m 3 . Figure 2 Typical particle size distribution Method Approximate useful range m Dry sieving 100 0

45、00 to 50 Wet sieving 100 000 to 10 Electrical sensing zone 800 to 1 Microscopy (light) 150 to 1 Sedimentation and elutriation 75 to 2 Microscopy (electron) 1 to 0.01 0 10 20 30 40 50 60 70 80 90 100 Cumulative per centage by mass passing sieve Mesh size d 10 d50 d90BS 8439:2005 6 BSI 13 May 2005 Tab

46、le 2 Recommended minimum quantity of granular solids to be sieved based on maximum particle size 5.3 Particle and bulk density 5.3.1 Particle density ( ) 5.3.1.1 General True particle density is the mass of a particle divided by the volume of the particle excluding open and closed pores. NOTE Closed

47、 pores are cavities not communicating with the surface of the particle. Apparent particle density is the mass of a particle divided by the volume of the particle excluding open pores but including closed pores. Effective particle density is the mass of a particle divided by the volume of the particl

48、e including both open and closed pores. 5.3.1.2 Measuring method The method for measuring particle density is simple and is usually based on the principle of liquid displacement. However it varies from one powder or bulk material to another, and from one size grade to another for a particular materi

49、al. Further information on the methods for measuring particle density for different materials are given in BS EN ISO 787-10, BS EN 196-6, BS 8122, BS 1016108.5 and BS 1377-2. 5.3.2 Bulk density ( *) 5.3.2.1 General Bulk density is the mass of a powder or bulk material, inclusive of moisture, divided by the volume occupied by the particles, the voids and moisture. In general for mater