Best Practice Design, Maintenance and Troubleshooting of … · 2019. 2. 4. · 2.13 Conveyor feeding and discharge 49 2.14 Electrical 50 2.15 Some tips to achieve cost savings in

Best Practice Design, Maintenance and Troubleshooting of Conveyors and Chutes

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Presents

Best Practice Design, Maintenance and Troubleshooting of Conveyors and Chutes

Revision 5

Ganesh Jayaraman B Eng (Mech)

Editor: Vernon Benjamin GECC (Mech/ Electrical), SAIMechE

Website: www.idc-online.com E-mail: [email protected]

IDC Technologies Pty Ltd PO Box 1093, West Perth, Western Australia 6872 Offices in Australia, New Zealand, Singapore, United Kingdom, Ireland, Malaysia, Poland, United States of America, Canada, South Africa and India Copyright © IDC Technologies 2010. All rights reserved. First published 2008 ISBN: 978-1-921007-97-2

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Trademarks All logos and trademarks belong to, and are copyrighted to, their companies respectively. Acknowledgements IDC Technologies expresses its sincere thanks to all those engineers and technicians on our training workshops who freely made available their expertise in preparing this manual.

Contents 1 Introduction 1 1.1 Introduction 1 1.2 Classification and characteristics of materials 1 1.3 Properties of the conveyed material 3 1.4 Classification of conveying machines 11 1.5 Selection of conveying machines 12 1.6 Trends 13

2 Belt Conveyors 15 2.1 Applications 15 2.2 Conveyor nomenclature and arrangement 21 2.3 Effect of material characteristics on belt conveyor 22 2.4 Capacity 22 2.5 Belt conveyor idlers 26 2.6 Belt tension, power, and drive engineering 28 2.7 Belt selection 38 2.8 Relative advantages and disadvantages of hot vulcanized,

cold vulcanized and mechanical splices 43 2.9 Conveyor belt selection 44 2.10 Pulleys and shafts 47 2.11 Concave and convex curves 48 2.12 Belt takeups, cleaners and accessories 48 2.13 Conveyor feeding and discharge 49 2.14 Electrical 50 2.15 Some tips to achieve cost savings in belt conveyors 52 2.16 Nomenclature 52

3 Mechanical Conveyors 55 3.1 Introduction 55 3.2 Screw conveyors 55 3.3 Power requirement of screw conveyors 65 3.4 Vertical screw conveyor 65 3 5 Bucket elevators 68 3.6 Flight conveyors 83 3.7 Apron conveyors 95 3.8 Vibratory conveyors 111

vi Contents

4 Pneumatic and Hydraulic Conveying 115 4.1 Preface 115 4.2 Introduction 115 4.3 Negative pressure pneumatic conveying systems 116 4.4 Positive pressure pneumatic conveying systems 122 4.5 Negative-positive pressure pneumatic conveying systems 125 4.6 Hydraulic conveying 130

5 Feeders 139 5.1 Introduction 139 5.2 Feeder loans 140 5.3 Belt feeders 144 5.4 Drive power 146 5.5 Apron feeders 147 5.6 Bar-flight feeder 149 5.7 Rotary drum, vane and value feeders 149 5.8 Rotary table feeders 151 5.9 Circular bin dischargers 153 5.10 Rotary plough feeders 154 5.11 Screw feeders 158 5.12 Reciprocating plate feeders 161 5.13 Vibratory feeders 162 5.14 Capacity 166 5.15 Support for trough feeders 167 5.16 Feeder flow patterns 168 5.17 Hopper gates 170 5.18 Conclusion 171

6 Storage and Flow in Bins and Bunkers 173 6.1 Introduction 173 6.2 Flow behavior of bulk solids 173 6.3 Classification of bulk materials 177 6.4 Design of bins and hoppers 178 6.5 Coarse materials 185 6.6 Pressure in mass flow bins 189 6.7 Shapes of outlets of bins and hoppers 194 6.8 Vibration of hopper walls 199

7 Transfer Chutes 201 7.1 Introduction 201 7.2 Transfer Chute Theory 202

Contents vii

7.3 General transfer chute design considerations 211 7.4 Design principles for chutes 211 7.5 Recommendations on chute design 214 7.6 Special chute design 215 7.7 Software availability for chute design 217 7.8 Installation and maintenance of chutes 219 7.9 Troubleshooting chutes 221

8 Conveyor Design and Safety 225

8.1 Design of conveyor belt 225 8.2 Factors determining conveyor belt selection 236 8.3 Capacity of a troughed belt 237 8.4 Vertical curves and tension calculations 239 8.5 Hazard vs risk 252

9 Operation, Maintenance and Troubleshooting 257 9.1 Introduction 257 9.2 Operation 257 9.3 General maintenance considerations 257 9.4 Splice failures 258 9.5 Mechanical splice failures 260 9.6 Splice inspections 262 9.7 Loading point considerations 262 9.8 Conveyor troubleshooting 263 9.9 Systematic approach to belt tracking 269 9.10 Systematic approach to tracking 270 9.11 Root cause process 271

Appendix A 275 Conveyor Belt Design

Appendix B 289 Trajectory Derivation

Appendix C 295 Estimation of Surcharge Angle

Appendix D 299 Belt Cleaners and Scrapers

viii Contents

Appendix E 311 Effect of Water Sprays on Belts

Appendix F 317 Practical Exercises

1

Introduction

1.1 Introduction Material handling plays an important part in the modern economy. No modern industrial plant: be it a coal mine, power plant, cement plant or a metallurgical plant, would be conceivable without an efficient transport system. Conveying equipment, of one or several types, is usually employed to mechanize material handling, loading and unloading operations. Conveying equipment works in conjunction with process equipment, such as that used for crushing, screening, blending etc. Overall mechanization of the processes becomes effective with appropriate selection of material handling equipment. This equipment not only substitutes manual labor, but also helps in the rational matching with all equipment responsible for the manufacturing processes, thereby enhancing the overall mechanization. Nowadays the operation and control of an entire plant is done from a properly networked centralized control room. Even the troubleshooting is carried out from there for detecting problem areas and initiating maintenance activities. The boiler stoking system in a thermal power plant requiring supply of coal round the clock, materials transported in blast furnaces and materials conveyed from underground and open pit mines are some of the important areas where material handling plays a vital role.

1.2 Classification and characteristics of materials The type of material handled and its physical as well as mechanical properties are the principal factors determining the type and design of conveying equipment and its accessories. Bulk materials include various heap-loaded, granular and powdered materials such as coal, ore, molding sand, saw dust, food grains and so on. Bulk materials are characterized by their physical and mechanical properties, such as:

• Lump size: This refers to the quantitative distribution of the particles of a particular bulk material according to their sizes and is also known as granulometric composition of the material. It is characterized by the particle size denoted by diagonal a (Figure 1.1) in mm. A number of parameters related to conveyors and auxiliary equipment are determined by this characteristic:

Best Practice Design, Maintenance and Troubleshooting of Conveyors and Chutes 2

Figure 1.1 Particle size

Lump size is determined through a consecutive screening of the material through meshes of different sizes. According to the uniformity of lumps in its composition, a bulk material is classified as sized or graded and unsized or non-graded.

A material, in which the ratio between the largest characteristic particle amax and the smallest characteristic particle amin is above 2.5, is considered to be unsized.

In sized materials, i.e. more or less homogeneous ones, amax: amin < 2.5. Sized materials are characterized by their average lump-size, for example:

2minmax aaaav

+=

In the unsized material, if the weight of a group of particles of lump size ranging between 0.8 amax and amax is greater than 10% of the total weight of the sample, then the material is characterized by lump-size amax and if it is otherwise, the characterization is done as 0.8 amax.

Tables 1.1 and 1.2 below show sizekWise classification of bulk materials and the recommended maximum lump size for different belt widths.

Table 1.1 Material characteristics

Material Characteristic Size (mm) Large-Lumped Over 160 Medium-Lumped 60 to 160 Small-Lumped 10 to 60 Granular 3 to 10 Fine 0.5 to 3 Very Fine Below 0.5

Introduction 3

Table 1.2 Maximum lump size for different belt widths

Belt width in mm Uniform lumps (mm) Mixed with roughly 80% fines (mm)

300 - - 350 50 100 400 75 125 450 100 150 500 100 175 600 125 200 650 125 250 750 150 300 800 150 300 900 175 325

1000 200 375 1050 200 375 1200 300 450 1350 300 500 1400 300 600 1500 350 600 1600 375 600 1800 450 600 2000 450 600

1.3 Properties of the conveyed material • Bulk density: It is the weight of the material per unit of volume in bulk (the volume

including the voids or air pockets present in the heap) and is generally denoted by γ with the units of measurement being tons/cubic meter and pounds/cubic inch. The bulk density of some of the most frequently used materials is mentioned in Table 1.2. It is an important consideration particularly when the capacity of a conveyor and the pressure on the walls and outlet of a hopper is to be calculated. The loose bulk density of a material can be determined by weighing samples of a known volume of uncompacted material. Most ores have varying bulk densities based on the amount of impurities present and the particle size. It is therefore essential to evaluate a reasonable number of samples in order to determine the likely range in the bulk density values.

• Specific weight: It is the weight of the material particles dried at a temperature of 100 to 105°C, with respect to the volume of water displaced by them. The specific weight of materials must be taken into account in order to calculate the capacity of pneumatic and hydraulic material handling equipment.

• Particle size and shape: The size of the lumps and the lump to fines ratio can influence the burden surcharge angle, while the particle shape can affect material flow in the chute and also the amount of belt wear.

• Maximum lump size: This is, in turn, dependent on the material characteristics and the crusher type employed. Large lumps tend to occur on conveyors handling mining products and primary ores. It is important for the maximum lump size to be established, as large slabs of material can pass through crushers.

• Angle of repose: This defines the mobility or flowability of material and is defined as the angle between the surface of a freely formed pile of the material and the horizontal. When a loose material spills unobstructed on a horizontal plane it assumes a slope. The angle of this slope with respect to the horizontal plane is its angle of repose: ϕ. (Refer Figure 1.2). The Angle of Repose is used as the base value for determining the burden surcharge angle.

• Angle of surcharge: This is the angle to the horizontal which the surface of the material assumes when the material is at rest on a horizontal supporting surface


vibrating vertically. This feature also defines the mobility or flowability of the material. Angle of surcharge is approximately 5 to 15° less than the angle of repose:

Figure 1.2 Angle of repose

• Internal friction angle: Materials with high internal friction angles will normally give higher burden surcharge angles and are less likely to slump when the belt flattens out at the discharge pulley. The internal friction angle can be determined by a material shear test, which in turn gives an indication of the behavior of different materials on a troughed belt conveyor.

• Coefficient of friction: This factor is taken into account for bulk material in contact with steel, wood, concrete, rubber and so forth when designing conveying machines and auxiliary equipment. The friction factor determines the angle of inclination of walls and ribs of hoppers, chutes and also the maximum inclination of certain conveyors.

• Abrasivity: The tendency of the particles of bulk materials to wear away the surface they are in contact with, when in motion, is known as the abrasivity of the material. The extent of abrasion depends on the hardness, surface condition, shape and size of the particles. Some bulk materials such as bauxite, iron ore, sand and coke are highly abrasive.

• Specific properties: These include moisture content, stickiness, fragility, hygroscopy, toxicity, corrosiveness etc. All these properties need to be considered when designing conveying machines and auxiliary equipment, and effective measures are taken to neutralize their harmful influence. Let us briefly discuss some of these properties:

• Moisture Content: Tends to have a marked influence on the burden surcharge angle as well as slumping of the conveyed material at the discharge pulley.

• Cohesion: This property is based on the angle of repose, the method of classifying the cohesive properties of a material is provided by ISO 3435.

• Temperature: Is a very important consideration. Any material temperature that is significantly higher than the ambient temperature may prove detrimental to the belt cover, necessitating the use of a special heat-resistant rubber (see Table 1.3 and Table 1.4).

Introduction 5

Table 1.3 Properties of most commonly used bulk material (approximate values)

Material Bulk Density, γ Angle of Repose, ϕ

Anthracite, fine, dry 0.8 to 0.95 45

Gypsum, small-lumped 1.2 to 1.4 40

Clay, dry, small-lumped 1.0 to 1.5 50

Gravel 1.5 to 1.9 45

Foundry sand, shake-out 1.25 to 1.30 45

Ash, dry 0.4 to 0.6 50

Limestone, small lumped 1.1 to 1.5 38

Coke 0.36 to 0.53 50

Wheat 0.65 to 0.83 35

Saw dust 0.16 to 0.32 39

Sand, dry 1.4 to 1.65 45

Iron ore 2.1 to 2.4 50

Coal, run of mine 0.8 to 1.0 38

Cement, dry 1.0 to 1.3 40

Crushed stone, dry 1.8 45

Slag, blast furnace, crushed 1.3 to 1.4 25


Table 1.4 Bulk material characteristics

Material

Material bulk/density (kg/m3)

Surcharge angle degrees

Recommended maximum inclination degrees

Code

Alum, fine 721-802 B35 Alum, lumpy 802-962 D35 Alumina 802-1042 10 10-12 B27M Ammonium nitrate 721 •C36NUS Asbestos shred 320-401 E46XY Ash, black, ground 1683 15 17 •B35 Ashes, coal, dry, 13mm and under

561-641 20 20-25 C46TY

Ashes, coal, dry, 76mm and under

561-641

D46T

Ashes, coal, wet 13mm and under

721-802

25

23-27

C46T

Ashes, coal, wet 76mm and under

721-802

C46T

Ashes, fly 641-721 20 20-25 A47 Ashes, gas-producer, wet 1250 D47T Asphalt, binder for paving

1283-1363

C45

Asphalt, crushed, 13mm and under

721

C35

Bagasse 112-160 E45Y Bark, wood, refuse 160-320 20 27 E46Y Barley 609 10 10-15 B15N Barytes, powdered 1924-2245 B26 Bauxite, ground, dry 1090 15 20 B26 Bauxite, mine run 1283-1443 15 17 037 Bauxite, crushed 76mm and under

1202-1363

20

D37

Bentonite, crude 561-641 D46X Bentonite, 100 mesh and under

802-962

20

A26XY

Bones 545-641 * Bonemeal 882-962 B36 Borax, 50mm to 100mm lumps

962-1042

D36

Borax, 40 to 50 mm lumps

882-962

D36

Brewer's grain, spent, dry 401-480 C45 Brewer's grain, spent, wet 882-962 C45T Brick, hard 2004 D47Z

Introduction 7

Material




Code

Brick, soft 1603 D47 BuckWheat 641-673 10 11-13 B25N Carbon, black, pefletised 320-401 B15Q Cardon, black, powder 64-112 •A35Y Carborundum, 61mm and under

1603

D27

Cement, Portland 1507 20 20-23 A26M Cement, Portland, aerated 962-1202 A16M Cement rock (see limestone)

1603-1764

D36

Cement clinker 1202-1523 15-20 18-20 D37 Cement mortar 2132 37Q Chalk, lumpy 1202-1363 D26 Chalk, 100 mesh and under

1042-1202

A46MXY

Charcoal 289-401 15 20-25 D36Q Chips, paper mill 320-401 E45 Chips, paper mill, softwood

192-480

E45

Clay (see also bentorite, diatomaceous earth, fullers earth, kaolin and Marl) Clay, calcined 1283-1603 B37 Clay, dry, fines 1603-1924 15 20-22 C37 Clay, dry, lumpy 962-1202 15 18-20 D36 Coal, anthracite, river or culm, 32mm and under

962 15 18

B35TY

Coal, anthracite, sized 882-962 15 16 C26

Coal, bituminous, mined 50 mesh and under

802-866 20 24 B45T

Coal, bituminous, mined and sized

721-882

15

16

Coal, bituminous, mined, run of mine

721-882 20 18 D35T

Coal, bituminous, mined slack, 13 mm and under

689-802 20 22 C45T

Coal, bituminous, stripping, not cleaned

802-962 D36T

Coal, Lignite 641-72 20 22 D35T Coke, loose 369-561 18 D47QVT Coke, petroleum calcined 561-721 20 D36Y Coke, breeze. 64mm and under

401-561 15-20

20-22

C37Y

Concrete, 51mm slump 1764-2405 24-26 D26 Concrete, 102mm slump 1764-2405 20-22 D26


Material




Code

Concrete, 152mm slump 1764-2405 12 D26 Copper ore 1924-2405 20 •D27 Copper ore, crushed 1603-2405 D27 Copra, lumpy 353 10 9 D25 Com grits 641-721 B25W Cryolite, dust 1202-1443 A36 Cryolite, lumpy 1443-1603 D35 Diatomaceous earth 176-224 A36MY Dolomite, lumpy 1443-1603 22 D26 Earth, as excavated - dry 1122-1283 15 20 B36 Earth, wet, containing clay

1603-1734

20

23

B46

Feldspar, 13mm screenings

1122-1363

20

18

B36

Feldspar, 38mm to 76mm lumps

1443-1734

15

17

D36

Feldspar, 200 Mesh 1603 Fish, meal 561-641 B45W Flour, wheat 561-641 21 A45PN Flue dust, boiler house, dry

561-641

A17MTY

Fluorspar, 13mm screenings

1363-1683

C46

Fluorspar, 38mm to 76mm lumps

1734-1924

046

Flay ash, dry (see flue dust)

Foundry sand, loose (see sand)

1283-1443

B47

Foundry refuse, old sand cores, etc

1122-1603

D37Z

Fullers earth, dry 481-561 10 B26 Fullers earth, oily 962-1042 B26 Fullers earth, oil filter, burned

641

B26

Fullers earth, oil filter, raw

561-641

15

20

•B26

Garbage, household 802 •E45VW Glass batch 1283-1603 20-22 D27Z Granite, 13mm screenings

1283-1443

C27

Granite, 38mm to 76mm lumps

1363-1443

D27

Granite, broken 1523-1603 027

Introduction 9

Material




Code

Gravel, bank run 1443-1603 20 20 Gravel, dry, sharp 1443-1603 15-17 D27 Gravel, pebbles 1443-1603 15 12 Q36 Gypsum dust, non-aerated

1491

Gypsum dust, aerated 962-1122 20 23 A36Y Gypsum, 13mm screenings

1122-1283

20

21

C36

Gypsum, 38mm to 76mm lumps

1122-1283

15

15

D26

Ice, crushed 561-721 D16 llmenite ore 2245-2565 B27 Iron ore 1603-3206 15 18-20 •D36 Iron ore, crushed 2164-2405 20-22 •C26 Iron oxide, pigment 401 20 25 A45 Kaolin clay 76mm and under

1010

15

19

036

Kaolin talc, 100 mesh 673-898 20 23 A46Y Lead ores 3206-4329 15 15 'B36RT Limestone, agricultural 3mm and under

1090 20 B26

Limestone, crushed 1363-1443 20 18 C26X Limestone, dust 1283-1363 20 A46MY Malt, meal 577-641 E25 Manganese ore 2004-2245 20 20 'D37 Nickel-cobalt, sulphate ore

1282-2405

•D27T

Oats 417 10 10 C25M Paper pulp stock 641-962 •E15MV Phosphate, acid fertilizer 962 15 13 B25T Phosphate, triple super ground fertilizer

801-882 20 30 B45T

Phosphate rock, broken, dry

1202-1363

15

12-15

026

Phosphate rock, pulverized

962

20

25

B36

Pyrites, iron 52mm to 76mm lumps

2164-2325

D26T

Pyrites, pellets 1924-208 C26T Quartz, dust 1122-1283 A27Y

Quartz, 13mm screenings 1283-1443

C27Z

Quartz 38mm to 76mm 1363-1523 027Z


Material




Code

lumps

1.3.1 Estimation of surcharge angle In the absence of reliable information on the surcharge angle, the following method may be employed to serve as a guide in the selection of a suitable value. The process is based on reducing the angle of repose and allows for:

• Belt velocity and angle of inclination at the loading point • Material properties • Special allowance for trippers

The nominal surcharge angle in degrees is given by the equation, Surcharge angle = X - Kv - Km - Ks Where: X is the angle of repose in degrees Kv is the velocity or slope reduction allowance in degrees Km is the material reduction allowance in degrees and Ks is the special reduction allowance in degrees Velocity/ slope reduction allowance - Kv This factor takes into consideration both the belt velocity as well as the angle of the conveyor at

the loading point. Values of Kv for a wide range of belt velocities and loading angles are given in the table below. These values are, in turn, proportional to the time taken for accelerating the material at the loading point, assuming the coefficient of friction between the belt and the material as 0.5. These values are for typical transfers in which some amount of material is redirected at the loading point. These values could reduce further in the event of there being effective material redirection. On the other hand, they could increase in the event of the feed chute not providing any material redirection (see Table 1.5).

Introduction 11

Table 1.5 Typical Kv values in degrees

Belt velocity in m/sec Conveyor angle at loading point 1 2 3 4 5 6

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

2 2 2 2 2 2 3 3 3 3 3 3 4 4 4 4 5

4 4 4 4 5 5 5 5 6 6 6 7 7 8 8 9 10

6 6 6 7 7 7 8 8 8 9 9 10 11 11 12 13 15

8 8 9 9 9 1 1 1 1 1 1 1 1 1 1 1 2

10 10 11 11 12 12 13 13 14 15 16 17 18 19 21 22 24

1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2

Material reduction allowance - Km Table 1.6 gives the values of Km for different materials as described.

Table 1.6 Material reduction allowance - Km

Special reduction allowance - Ks The value of Ks for belt sag, trippers and horizontal curves will depend partly on the design features of the conveyor and also the nominal surcharge angle obtained from other factors. In case the nominal surcharge angle is high, say more than 15°; there must be some additional reduction in the surcharge angle to account for these special features.

Typical values of Ks For conveyors with tripper – 5 to 10° For high belt sags exceeding 1% of the idler centers - 5° Refer to Appendix C for surcharge angles

1.4 Classification of conveying machines Owing to the wide range of conveying machines available, such as those differing in the principle of operation, design features, direction and means of conveyance, a general classification of material handling equipment is almost impossible.

Material Km in degrees Fine material having 5% moisture or interlocking material 5° Dry material with low fines content such as crushed rock 10° Dry, free flowing fine material 15°


According to their principle of operation, conveying machines can be categorized as those based on intermittent action and continuous action, the salient features of which are mentioned below.

1.4.1 Intermittent action machines • Cyclic operation is a characteristic feature of these machines • They operate on an alternately reciprocal principle; they run loaded in one direction

and idle in the other • Examples of intermittent action machines include cars, trucks, rail mounted cars, cable

cars and tractors • Loading and unloading are generally accompanied by stoppages • They possess great flexibility in the path of transport, with the path being provided

with a number of branches at times • They are suitable for small and medium capacity work • They are difficult to put into automatic operation

1.4.2 Continuous action machines • A feature specific to continuous action machines is that their load carrying member

conveys the load in a practically uninterrupted stream or in small successions (buckets, tubs etc)

• They move along a precisely determined path • Examples of this type include various types of conveyors and pneumatic and hydraulic

transport installations • They are suitable for all capacity ranges, from small to very high • They are most suited for automatic operation

1.4.3 Auxiliary equipment Auxiliary equipment forms a special group and is designed for operation in conjunction with conveying machines. They are not an independent means of conveyance. Auxiliary equipment comprise chutes, troughs, hoppers, gates, feeders and so on.

1.5 Selection of conveying machines Following are the technical factors to be considered when selecting a conveying machine:

Nature and properties of the material to be conveyed: • Required capacity of the equipment – If the capacity is high, economic

considerations will dictate selection of the equipment that is compact and low in cost. • Direction and length of conveying run – This is of prime importance in selecting the

equipment type. Certain types of machines easily permit change of direction in one or both planes; others operate in a straight path and in one direction. While some are adopted to convey materials a considerable distance, others are limited by their length.

• Storage of material at the head and tail end – The method of loading and unloading of material also has an important bearing in the selection of a conveying machine. While some of them are self loaders, others may require certain additional loading devices. Loose material can be stored in heaps, from which they are loaded on to the conveying machines with the help of buckets, scrapers or by other means. The material stored in a bin is discharged on to the conveying machine by gravity.

• Processing steps and the movement of loads – In most cases, conveying machines are related to the overall manufacturing cycle, depend on it and serve to carry a load processed en route.

• Specific local conditions – These include the area of the site at disposal, its topography, type and design of the building, mutual layout of handling machines and

Introduction 13

processing equipment, humidity, ambient temperature, environment protection etc. It is also important to know whether the machine will be installed outdoors or indoors.

After selecting the machine on the basis of the technical factors discussed above, a detailed

review also has to be carried out from the economic point of view. An optimum solution would be the type of conveying machine that meets all the processing requirements while ensuring a high degree of mechanization and favorable working condition. Such equipment will, in the long run, ensure minimum per unit handling cost and will recoup the initial outlay in the shortest possible time.

1.6 Trends Following are the most visible modern trends in bulk material handling:

• Reduction in the amount of movement of bulk load to a minimum. This means that load is to be handled from the initial to the final point of conveyance, with minimum number of transfers, for example, by using a single or minimum number of machines. It must be ensured that the shortest path is always taken. On the other hand, there is a trend towards bringing the process plant closer to the source of material.

• Increase in handling capacity. • More reliable operation, improvement in working condition and minimum

maintenance requirement. Which is an essential prerequisite for automation of the manufacturing process.

• Automatic control of individual conveying machines and group of installations, automatic loading/ unloading operations and distribution of loads.

• Light weight machines of small size.


00_CC_prelims_r5.pdf01_CC_TOC_r5.pdf02_CC_01_r4.1.pdf

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