Fundamentals-REV-5.pdf

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An easy-to-understand introduction to

slurry pumps and systems

These are people. This is the shell or

volute of a very, very, very, very large slurry pump.

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Meet Digsby. He appears whenever we want to give you a mountain of information but only have room for a mole hill. He tells you where to dig deeper in other sources and in the textbook, “Slurry Transport Using Centrifugal Pumps,” written by Drs. Kenneth C. Wilson, Anders Sellgren Roland Clift and GIW’s VP of Engineering Graeme Addie. The textbook is available from Kluwer Publishing (www.wkap.nl).

Reader’s Guide

giwindustries.com

Does your slurry have an attitude? Is it caustic? Corrosive? Abrasive? Erosive? (Or some combination thereof?) If so, talk to us. We can make the biggest, baddest, meanest, nastiest slurry behave. We are the expert in slurry transport, so challenge us to solve your production delays or to improve your slurry pumping systems.

Editor & Designer Mary A. Sicard Project Editor Thomas Mueller Production Controller Pam Welty

Tech Team Bob Courtwright, Tom Wujcik, Richard Inglett, Reab Berry and Kevin Kuehne

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanic, photocopy, recording or otherwise, without the prior

written permission of the copyright owner.

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5000 Wrightsboro Rd. • Grovetown, Ga. 30813 Phone: 706.863.1011 • Fax: 706.863.5637

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5 Slurry Pump Fundamentals

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FEATURES ... 52 APPLICATION ... 52 SIZE RANGE ... 52 LSA-S SERIES ... 52 FEATURES ... 52 APPLICATION ... 53 SIZE RANGE ... 53 Rubber Pumps ... 53 LCC RUBBER-LINED SERIES (LCC-R) ... 53 FEATURES ... 54 APPLICATION ... 54 SIZE RANGE ... 54 LSR ... 54 FEATURES ... 54 APPLICATION ... 55 SIZE RANGE ... 55 Vertical Pumps ... 55 VERTICAL ... 55 FEATURES ... 55 APPLICATIONS ... 56 SIZE RANGE ... 56

High-Pressure, Multi-Stage Slurry pumps ... 56

WBC ... 56 FEATURES ... 56 APPLICATIONS ... 56 SIZE RANGE ... 56 TBC ... 57 FEATURES ... 57 APPLICATIONS ... 57 SIZE RANGE ... 58

Chapter 9: Application Guide ... 61

Selection by Duty ... 61

COARSE PARTICLES ... 61

FINE PARTICLES ... 61

SHARP (ABRASIVE) PARTICLES ... 62

HIGH PERCENT SOLIDS ... 62

LOW PERCENT SOLIDS ... 62

FIBROUS PARTICLES ... 62

Duties Related to Head and Volume ... 62

HIGH HEAD ... 62

VARYING HEAD AT CONSTANT FLOW ... 62

VARYING FLOW AT CONSTANT HEAD ... 62

HIGH SUCTION LIFT ... 63

HIGH FLOW ... 63

LOW FLOW ... 63

FLUCTUATING FLOW ... 63

Duties Related to Slurry Type ... 63

FRAGILE SLURRIES ... 63

HYDROCARBON SLURRIES (OIL AND REAGENTS CONTAMINATED) ... 64

HIGH TEMPERATURES ABOVE 212˚F (100˚C) SLURRIES ... 64

HAZARDOUS SLURRIES ... 64

CORROSIVE SLURRIES (LOW PH) ... 64

HIGH VISCOSITY FLUIDS (NEWTONIAN) ... 64

HIGH VISCOSITY FLUIDS (NON-NEWTONIAN) ... 64

Selection by Industrial Application ... 65

HARD ROCK MINING ... 65

OIL SANDS ... 66

PHOSPHATE ... 66

FGD ... 66

INDUSTRIAL PROCESS ... 66

Chapter 10: Computerized Pump Selection ... 67

Slysel ... 67

SOFTWARE AND HARDWARE REQUIREMENTS ... 68

ORDER INFORMATION ... 68

Chapter 11: General Maintenance ... 69

Maintenance ... 69

RECOMMENDED MAINTENANCE SCHEDULE ... 69

DAILY ... 70 WEEKLY ... 70 QUARTERLY ... 70 SEMI-ANNUALLY ... 70 Impeller Removal ... 71 IMPELLER BALANCING ... 71 Fastener Torque ... 72 TORQUE ACCURACY ... 72 TORQUE CHARTS ... 72 Mechanical Seals ... 72 Bearing Temperatures ... 73

LUBRICATION – OIL OR GREASE? ... 74

CAUSES OF BEARING FAILURES ... 75

Vents and Breathers ... 76

Chapter 12: Total Cost of Ownership ... 79

Importance of making Smart Pump Purchases ... 79

How GIW Can Help ... 80

Predicting Wear ... 80

Calculating Energy Costs ... 81

Chapter 13: Troubleshooting ... 83

Why Isn’t My Pump Pumping? ... 83

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Chapter 1: What Is Slurry? 9 Slurry Pump Fundamentals

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Chapter 1:

What Is Slurry?

• Slurry is a mixture of something solid and a liquid. • The solids in a slurry can be anything from gold to gravel,

copper to coal, sand to cement. They can also be crystalline, sharp, flaky, fibrous or frothy.

• Almost any solid can be transported hydraulically via a slurry pipeline using a slurry pump.

• Clear water is the primary liquid for slurry transport, but other liquids such as acids, alcohol and light petroleum may be used.

In the mining industry, slurry pumps are used to transport slurries. The production of fertilizer, for example, involves massive slurry transport operations. To make the fertilizer, phosphate matrix is recovered by draglines in open-pit mining operations. (Draglines are huge electrically powered excavating machines with buckets that hold as much as 150 tons.) The matrix is then slurried (mixed with water) and pumped to the wash plant through pipelines with a typical length of about six miles.

See Chapter 1.1 Applications of Slurry Transport in “Slurry Transport Using Centrifugal Pumps.”

Slurry Pumps vs. Water Pumps

Slurry pumps can be massive and often have replaceable wear parts. They are usually much heavier and larger than clear water pumps sized for the same head and flow. Some of the reasons for their larger size are:

EXCESSIVE PUMP DISCHARGE PRESSURE ... 83

EXCESSIVE LEAKAGE AT SHAFT SEAL ... 83

PUMP DELIVERS INSUFFICIENT FLOW RATE ... 83

INCREASE IN BEARING TEMPERATURE ... 84

BEARING CONTAMINATION ... 84

HIGH TEMPERATURE OR LEAKAGE AT THE STUFFING BOX ... 84

OVERHEATING OF PUMP CASING ... 85

PUMP CASING LEAKS ... 85

PUMP FLANGE LEAKS ... 85

MOTOR OVERLOAD ... 85

VIBRATIONS OR ABNORMAL NOISES ... 86

Help Is Here ... 86

Chapter 14: Appendix ... 89

Temperature Conversion Chart ... 89

Mass Conversion Chart ... 89

Velocity Conversion Chart ... 89

Flow Conversion Chart ... 90

Volume Conversion Chart ... 90

Length and Distance Conversion Chart ... 91

Chapter 15: Glossary ... 93

Chapter 16: References ... 99

Chapter 17: Where It All Comes Together ... 101

Capabilities ... 101

TESTING AND DEVELOPMENT ... 101

DESIGN ENGINEERING ... 101

MANUFACTURING ... 102

PRODUCTS ... 102

History ... 103

Ownership ... 103

How To Contact GIW ... 103

GIW INDUSTRIES ... 104

SERVICE CENTERS ... 104

GIW REGEN SERVICE CENTER ... 104

ARROYO PROCESS EQUIPMENT INC. ... 104

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Chapter 1: What Is Slurry? 11 Slurry Pump Fundamentals

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The solids transported in this dredging operation were as large as a hard hat.

These limits are determined by the pump’s ability to withstand the forces associated with operating the pump, such as pressure, vibration, axial thrust and the stability of the pump at various flows.

See Chapter 2.2 Basic Relations for Flow of Simple Fluids in “Slurry Transport Using Centrifugal Pumps.”

Solids Limitations

Theoretically, there are no limits on what can be hydrotransported. In prac-tice, however, the size and shape of the solids limit what can be pumped because of the risk of

the solids blocking passage through the pump.

The maximum particle size of material that can be transported in a slurry pump is approximately 12 in. (300 mm). However, sphere passage in large dredge pumps can be up to 18 in. (450 mm).

See Chapter 2.4 Basic Relations for Slurry Flow in “Slurry Transport Using Centrifugal Pumps.”

Slurry pumps, like the one shown above, are usually much larger than water pumps. • Slurry pumps are

con-structed of special materi-als because of the abrasive nature of most slurries. These materials often require special bolting and assembly arrangements. • Slurry pump components

are normally thicker than components for water pumps.

• Slurry pump shafts and bearings are often larger than those on water pumps, because slurry pumps handle various sizes and concentrations of solids.

• Slurry pumps usually run slower than water pumps to help reduce parts wear.

Water pumps account for the largest percentage of pumps installed in the process industry. For every five slurry pumps, 95 water pumps are in opera-tion.

The purchase and operating costs of a slurry pump are often many times that of a standard water pump. (Some industry experts put the operating costs of slurry pumps compared to those of water pumps at 80:20.) This is why the correct selection and application of your slurry pump is essential to your operation’s efficiency.

Flow Limitations

The flow limitations for a slurry pump installation are from 35 - 132,000 gpm (8 - 30000 m3_/hour).

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Chapter 2: Slurry Pumps Defined 13 Slurry Pump Fundamentals

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Chapter 2:

Slurry Pumps Defined

A slurry pump is a type of centrifugal pump designed for transporting solids. It isn’t designed for pumping clear liquids. The less liquid that’s used in slurry pumping, the better. It doesn’t make sense to add additional fluids that will need to be removed later in the process.

A centrifugal pump uses centrifugal force to impart velocity (speed) to a fluid or slurry. Centrifugal force pushes something outward when it’s spinning rapidly around a center.

Con-sider a swing ride at the fair. As the rotational speed increases, the people in seats slide away from the center pole toward the swings’s outer edge.

Another example? Centrifugal force causes water to be thrown from an automobile tire while it’s rotating.

A centrifugal pump acts on the same principle, except the tire becomes an impeller and the vanes help move the water. However, the pump impeller doesn’t do all the work. It’s only part of the pump design. The medium being pumped must be

controlled. Centrifugal force pushes something

outward when it’s spinning rapidly around a center.

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Chapter 2: Slurry Pumps Defined 15 Slurry Pump Fundamentals

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Impeller Volute (Shell)

Vanes

The volute or pump shell helps control the flow.

DRY

Most horizontal slurry pumps are installed dry, where the drive and bearings are kept out of the slurry and the wet end is closed. The pumps are free standing and clear from any surrounding liquid.

SEMI DRY

A special arrangement can be used for dredging applications, where horizontal pumps are used with the pump wet end and bearings flooded and a dry drive. This requires special sealing arrangements for the pump bearings.

The sump pump has a flooded wet end installed at the end of a cantilever shaft (no submerged bearings) and a dry drive. WET

A fully submersible pump and drive are necessary for certain slurry pump applications.

Wear Conditions

The following slurry classifications are used in pump design selection to ensure good wear performance under a variety of working conditions and applications.

These classifications are based on GIW’s proprietary selection program Slysel. This program is discussed in detail in “Chapter 10: Computerized Pump Selection.”

Wet End

Part of the pump that gets wet from the pumping fluid. It includes the: • Shell • Impeller • Hub/Suction Liner • Shaft Sleeve/ Stuffing Box t e k r a M Application e g r a h c s i D l l i M SAGMill,RodMill,BallMill d e e F e n o l c y C Primary,Secondary,FinishingScalping d e e F g n i r e t a w e D o r d y H , r o t a r a p e S c i t e n g a M , n e e r c S e n i F , n e e r c S r e t l i F , r e k a h S r o n e e r c S g n i t a r b i V , r o t a r a p e S d e e F p m u P s g n i l i a T FirstStagePump,BoosterPump,TailingsFeed p m u P e m u l F , p m u P r e n e k c i h T Underflow,Overflow,ThickenerFeed r e t a W y t r i D Process,ProcessReturn,BoosterTransferPump e g d e r D Hydrotransport,Jetting,BoosterPump,Ladder g n i l d n a H r e t a W h s a W , d e e F e n o l c y C , p m u P

The volute (pump shell) helps control the flow and transforms the velocity of the liquid into static pressure and controls the product being pumped. “Chapter 3: Slurry Pump Design & Components” covers the parts of a slurry pump in greater detail.

See Chapter 8: Centrifugal Pumps in “Slurry Transport Using Centrifugal Pumps.”

Markets & Applications for Slurry Pumps

Installations

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Chapter 3: Designs & Components 17 Slurry Pump Fundamentals

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Chapter 3:

Slurry Pump Design &

Components

Basic Designs

The three basic slurry pump designs are horizontal, vertical and submersible.

Basic Components

The basic components of a slurry pump are the: • Impeller • Suction plate/liner • Shell • Sealing arrangement

• Drive • Bearing assembly

Horizontal Vertical Submersible

n o i t a c i f i s s a l C Example e v i s a r b A y l d l i M : 1 s s a l C ThickenerOverflow e v i s a r b A y l t h g i l S : 2 s s a l C ScreenFeed e v i s a r b A e r o M y l t n a c i f i n g i S : 3 s s a l C SandPlantOperation e v i s a r b A y l h g i H : 4 s s a l C MillDischarge,TarSand s g n i l i a T d n a t r o p s n a r t o r d y H

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Vane Designs

The impeller vanes are the guts of the impeller. Vane design is critical to wear and hydraulic performance of the pump.

Shell

The shell derives its name from a spiral-shaped volute casing surrounding the pump impeller. One function of the shell is to pick up the flow coming from around the impeller, convert it into a desirable flow pattern and direct it to the pump discharge.

Another function is to reduce the flow velocity and convert its kinetic energy to pressure energy.

SHELL TYPES

Volute, semi circular and circular are shell types or casings. No matter which type shell is selected, there’s a trade off be-tween wear and efficiency. The more volute the shell, the greater the efficiency and the wear. The more circular the shell, the less the wear and the efficiency.

A volute casing is like a seashell. It’s a curved funnel. It reduces the speed of the liquid and increases the pressure. This is the most popular design today. In the circular casing design, the impeller has a constant clearance between its outside diameter and casing.

The mathematical logarithm found in a seashell is used in all pump design.

Solid Shell Split Shell

The impeller, shell and suction liner are the key wet end wear components on all slurry pumps. The pump performance is determined by the design of these three parts. All other mechanical parts serve to seal, support and protect them.

Impeller

The impeller attaches to the pump shaft and imparts energy to the fluid being pumped. There are three types of

impellers: closed, open and semi open. CLOSED IMPELLERS

Closed impellers are preferred in slurry pump applications where high efficiencies are required.

OPEN IMPELLERS

Open impellers are slightly less efficient but are more effec-tive for applications with a slurry that’s a mixture of a fluid, solid and gas such as froth pumping.

Closed Impeller Open Impeller Bearing Assembly Shell Impeller Suction Plate/Liner

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Shaft and Bearings

SHAFT

The shaft transmits torque from the drive to the impellers. BEARINGS

Rolling element bearings are used to support the shaft and absorb axial thrust. Lubrication can be oil or grease. Oil

lubri-cation allows for higher speeds.

Drives for Slurry Pumps

There are three basic drive designs for slurry pumps: belt, gearbox and direct.

BELT DRIVES

Belt drives are used for both horizontal and verti-cal pumps, and include the motor, v–belt and sheaves. Belt drives allow for cost-effective speed changes by varying the diameter of the sheaves. GEARBOX DRIVES

Gearbox drives are used for horizontal pumps. They are typically used on larger motors and pumps. A gear reducer can change the output speed from the motor to the pump. It’s most often used for 300 hp and larger motors. DIRECT DRIVES

Direct drives are used for both horizontal and vertical pumps. This drive directly connects the motor to the pump shaft. Direct drives are the optimal selection when speed change isn’t neces-sary.

V-Belt Side-Mounted Drive

V-Belt Overhead Drive

Gearbox Drive Direct Drive Stuffing Box Mechanical Seal Expeller Split and Solid Shells

The shell of most hard metal pumps is one solid piece. A one-piece shell simplifies routine maintenance and is cost effective because of simpler sealing requirements.

The shell must be split for rubber-lined pumps so that the lining and parts can be replaced as needed.

Suction Liner

The suction liner is the part that has the highest wear, espe-cially in the nose/face area.

Shaft Seals

There are three shaft seal designs: stuffing box, mechanical seal and expeller. The basic function of a shaft seal is to separate rotating and non-rotating parts.

STUFFING BOX

This standard seal design uses a lantern ring and packing. MECHANICAL SEAL

A mechanical seal is used when gland water isn’t available or can’t be added to the process or when external leakage and process dilution are undesir-able.

EXPELLER

The expeller is a secondary impeller positioned behind the main impeller. An expeller is used in applications where mechanical seals don’t work. Expellers are a more cost-effective option than mechanical seals.

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Chapter 4: Wear Protection 23 Slurry Pump Fundamentals

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Chapter 4:

Wear Protection

Wear

Wear life is the most critical factor in the design of a slurry pump. Wear resis-tance is a key consideration for both hydraulic design and material selection.

See Chapter 10.2: Wear-Resistant Materials in “Slurry Transport Using Centrifugal Pumps.”

Corbrasion™

Corbrasion is GIW’s trademarked term for the combination of abrasion and corrosion that creates unique wear conditions in slurry pumps.

Abrasion is wear produced by hard particles that are moving and forced against a solid surface. The particles producing the abrasion are harder than the surface they are hitting. The particles usually have sharp, angular edges. Corrosion is the loss of material caused by the interaction between the pump material and chemical products within the slurry.

Selection of Wear Materials

The proper material selection helps combat the effects of Corbrasion. Material selection is based on:

• Solid size • Solid shape • Solid hardness

• Slurry temperature • Slurry pH • Slurry chemical content • Impeller speed

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steels would be destroyed by corrosive action. They are recommended for high boiling point liquids at elevated temperatures.

Elastomer Construction

Elastomers are available as urethane or natural rubber liners and impellers. Elastomer linings are usually specified when:

• The solids are fine.

• The particles do not have sharp edges. • The presence of tramp material is minimal. • Oils, solvents or hydrocarbons aren’t present. • The pH is less than 6.0.

• The head is below 131 feet (40 m). • The temperature is below 150° F (65° C).

Ceramic Wear Parts

Ceramic wear parts are used for highly abrasive slurries where parts are experiencing extreme wear. They are not suitable for impact and high-pressure applications.

Corrosion Resistance and Wear Resistance

This chart shows the relative corro-sion and wear resistance of various alloys, which may vary because of the application and other factors. HARD METAL CONSTRUCTION

Hard irons and steels, such as white cast irons and martensitic steels, are used most often in the construction of slurry pumps. White cast irons offer consid-erably higher wear resistance than steel.

White Irons

White iron is a cast iron that is free of graphite. Most of its carbon content is present in the form of hard carbides. GIW’s Gasite®_{white irons are:}

White iron is usually preferred when:

• The solids are greater than .25 inches (6 mm). • The pH is greater than 4.5.

• Temperatures are to 250° F (120° C). • The slurries are hydrocarbon based. • The particles are coarse or sharp.

• Tramp material or debris may be present.

Steels

GIW’s steels are martensitic and heat-resistant grades (18CS, HH and HK). Steels are distinguished by their ability to serve where carbon and low-alloy

e d a r G Gasite¨ _D_e_s_c_r_i_p_t_i_o_n V I d r a H i N 4G,6G ASTMA532,ClassI,TypeD o M -r C 18G,20G ASTMA532,ClassII r C -h g i H 27G,28G ASTMA532,ClassIII l a i c e p S 29G Ultra-highstrength/toughness l a i c e p S T32G,38G Eutectic/hypereutecticgrade l a i c e p S OS34G n o i s o r r o c d e v o r p m i h t i w r a e w h g i H s a h c u s s n o i t a c i l p p a e m o s r o f ( e c n a t s i s e r ) s d n a S l i O l a i c e p S 30G Regularcorrosive-erosiongrade l a i c e p S 40G Premiumcorrosive-erosiongrade l a i c e p S T90G Supercorrosive-erosiongrade T32G 38G 18G 28G OS34G 4G/6G 29G _40G

High-Alloy Martensitic Steels

T90G CD4MCU SS316 Ni-Resist 82D/83D 81D 80D/35C 65D Corrosion Resistance Wear Resistance

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0 20 40 60 80 100 120 140 160 180 200

Wear Resistance Index

T32G 18G OS34G 6G 29G 40G Marten. Steel CD4MCu 65D 82D/83D Alloys

Regular Wear Resistance Range Possible Wear Resistance Range

Wear Resistance Range

This chart shows the regular and possible wear resistance range for various alloys.

pH Ranges

This chart shows the relative pH range for various alloys.

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 T90G 40G OS34G 28G T32G 18G 4G pH

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Chapter 5: Hydraulics 29 Slurry Pump Fundamentals

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Chapter 5:

Hydraulics

Pumps and Curves

Pump efficiency is determined principally by two parameters (head and flow) in addition to other factors such as properties of the fluid, impeller design and motor speed.

An improperly applied pump with a high efficiency can be worn to total failure within just a few hours. A thorough knowledge of the duty is neces-sary to reduce wear on the pump. In fact, most pump problems arise because the pump’s performance characteristics don’t match the application require-ments. This results in higher power consumption, and shorter bearing and wear life. The system parameters and pump performance must be matched carefully to ensure efficient, trouble-free operation.

The easiest way to visualize this requirement is to consider two separate curves: a pump performance curve and a system curve.

A pump performance curve is a graphical representation of the head (hydrau-lic pressure) produced by the pump for various flow rates at a given speed. The curve is always downward sloping, which means head decreases as flow rate increases.

A system curve is a graphical representation of the head required for a given system at various flow rates. In slurries, the system curve is more complex and often resembles a “U” formation.

PERFORMANCE CURVE

A complete performance curve array includes:

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A system curve is a graphical representation of the head required for a given system at various flow rates.

40 0 0 1000 2000 3000 4000 5000 6000 80 120 160 200 240 280 7000

Total Dynamic Head

Gallons Per Minute

• Data about the head produced by the pump over a range of capaci-ties

• Power required to deliver a given flow and head

• Efficiency ratio of en-ergy transferred to energy required (power) for various flow rates • Net Positive Suction

Head (NPSH) required. (See NPSH section in this chapter.)

The curve data is based on clear water, so curves must be adjusted when pumping slur-ries. Your GIW representative

or Slysel, GIW’s proprietary selection program, can assist you with these calculations and modifications.

At a given speed, slurry pumps can be operated at a variety of flow rates. However, only one specific flow rate achieves the maximum efficiency. This is called the Best Efficiency Point (BEP).

The power to operate a pump can be calculated from the information pre-sented on the performance curve using one of the following formulas:

c i r t e M U.S. = P HxQxSG f f E x 7 6 3 = P H B HxQxSG f f E x 0 6 9 3 s r e t e M n i d a e H = H r u o H r e p s r e t e M c i b u C n i y t i c a p a C = Q t n e c r e P n i y c n e i c i f f E = f f E y r r u l S e h t f o y t i v a r G c i f i c e p S = G S s t t a w o l i K n i r e w o P = P r e w o p e s r o H e k a r B = P H B t e e F n i d a e H = H e t u n i M r e p s n o l l a G n i y t i c a p a C = Q t n e c r e P n i y c n e i c i f f E = f f E y r r u l S e h t f o y t i v a r G c i f i c e p S = G S

A pump performance curve is a graphical representation of the head produced by the pump at various flow rates.

400 rpm 40 0 0 1000 2000 3000 4000 5000 6000 80 500 rpm 600 rpm 700 rpm 800 rpm 900 rpm 1000 rpm 120 160 200 240 280 1100 rpm 60% _70% 75% 80% 82% 83% 83% 82% 80% 78% 75% 7000 NPSHR at 500 rpm NPSHR at 10 00 rpm 300 hp 250 hp 200 hp 160 hp 130 hp 100 hp 75 hp 50 hp 25 hp

Total Dynamic Head

Gallons Per Minute

Pump performance prediction is difficult. GIW has developed sophisticated computer models through years of experience and can predict performance before the pump is ever built. However, pump curves can be certified only by full-size performance testing in accordance with the Hydraulic Institute Standards in an approved laboratory.

See Chapter 8: Centrifugal Pumps in “Slurry Transport Using Centrifugal Pumps.”

SYSTEM CURVE

System curves represent graphically the energy (head) required to move slurry through a piping system (including process equipment) at various flow rates.

Required energy is plotted on the vertical axis and given in terms of head. Capacity is plotted on the horizontal axis and is given in cubic meters per hour or gallons per minute. System curves for liquids are always upward sloping, whereas slurry system curves may be “U” shaped and diffi-cult to predict. In most cases, slurry system curves can be determined only experimen-tally in a laboratory environ-ment. Your GIW representative can assist you in getting an accurate system performance curve test in the GIW Hydrau-lic Laboratory.

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If the suction pressure is too low, the pressure in the suction area decreases to the lowest possible pressure (the vapor pressure) of the pumped liquid.

Vapor Pressure and Cavitation

If vapor pressure is reached, vapor bubbles form and follow the liquid into the impeller to areas with higher pressure. The vapor bubble then collapses or implodes in these areas. This creates extremely loud noises. These small implosions are called cavitation.

CAVITATION

Cavitation is more than air bubbles in the liquid. In most cases, cavitation is the liquid boiling at ambient temperatures because of the reduction in pressure. Cavitation should be suspected when:

• Pump capacity is reduced.

• The head produced by the pump is reduced.

• Noise can be heard when the pump is running.

• Pitting or other damage can be seen on the pump impeller and shell. Cavitation can be an issue when the operations are at a high altitude or when pumping liquids at a high temperature. These variables may not have been considered during pump selection.

NPSHR

All pumps require a value for NPSH. This value is called Net Positive Suction Head Required (NPSHR). NPSHR is not a calculated value. It is a property of the pump. All pump curves show the NPSHR for assorted flows and speeds. However, the criteria for NPSHR must be defined for your application. The criteria can be based on a head requirement for a given flow rate and speed. As NPSH is reduced, head remains constant for a time and then begins to drop off.

operate a pump if cavitation is suspected. The problem must be corrected!

Don’t

THE INTERSECTION

Pumps always operate at the point where the system curve intersects the pump perfor-mance curve. This point is called the duty point. It repre-sents the capacity where the energy required to move the liquid through the piping system equals the energy transferred to the liquid by the pump.

Head

The Total Dynamic Head (TDH) is the sum of kinetic and potential energy per unit of fluid transferred from the impeller vanes to the fluid. In

pumping terminology, “head” is often used when referring to TDH. Head is usually expressed in meters or feet.

NET POSITIVE SUCTION HEAD (NPSH)

Net Positive Suction Head (NPSH) is an important concept for judging the suction behavior of a centrifugal pump.

A drop in the static pressure, particularly in the suction (inlet) area, occurs as the material flows across the pump impeller. The magnitude of this pressure decrease depends upon the: rotational speed, operating point, design of the impeller inlet, velocity and static pressure of the approaching flow and its density, and viscosity.

The static pressure of the liquid must be above the vapor pressure inside the pump to avoid cavitation. This is achieved by having sufficient pressure on the suction side of the pump and a well-designed pump inlet.

Pumps always operate at the point where the system curve intersects the pump curve.

400 rpm 40 0 0 1000 2000 3000 4000 5000 6000 80 500 rpm 600 rpm 700 rpm 800 rpm 900 rpm 1000 rpm 120 160 200 240 280 1100 rpm 60% _70% 75% 80% 82% 83% 83% 82% 80% 78% 75% 7000 NPSHR at 500 rpm NPSHR at 10 00 rpm 300 hp 250 hp 200 hp 160 hp 130 hp 100 hp 75 hp 50 hp 25 hp

Total Dynamic Head

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For slurry pumping systems, a head reduction up to five percent is usually acceptable. Therefore, the pump can be operated safely within these param-eters, which must be predetermined.

A similar process holds true for efficiency, but isn’t used as regularly as head. As NPSH is reduced, efficiency remains stable until the pressure reduction causes efficiency to drop. Too low of an NPSH can cause cavitation. NPSHA

The complete pump system must provide the Net Positive Suction Head Available (NPSHA) to function properly without cavitation. NPSHA is a system characteristic and must be calculated. The value of NPSHA must always be greater than the NPSHR. The safety margin against cavitation is defined as NPSHA minus NPSHR.

To calculate NPSHA, add all the pressure heads and then subtract all losses in the piping system on the suction side.

NPSHA = Atmospheric pressure (converted to head) + static head + pressure head – the product’s vapor pressure – the friction loses in the suction piping, valves and fittings CAUSES OF CAVITATION

What causes cavitation?

• The flow rate is too high for the given suction and speed. • Atmospheric pressure is too low.

• The application is at a high altitude.

• The pump speed is too high for given suction and flow. HOW TO FIND THE CAUSE

To find the cause of cavitation: • Use gauges.

• Check pump speed.

• Check pump suction (inlet) for blockage. • Refer to the pump performance curve.

See Chapter 8.3: Cavitation and Net Positive Suction Head or page 191, Net Positive Suction Head in “Slurry Transport Using Centrifugal Pumps.”

Pumping Froth

The transfer of froths with a slurry pump is a special-purpose application. The large proportion of air in froth adversely affects the pump performance. The usual relationships for predicting the pump performance don’t hold true. The selection process also requires special considerations.

Follow these steps when selecting a froth pump:

1. Oversize the pump. Oversizing the pump helps in handling froth by increasing the pump’s impeller eye diameter. This allows the pump to run at a lower speed.

2. Avoid pump throttling. The suction or inlet pipe must be at least the same size as the outlet pipe

3. Increase the sump height.

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Chapter 6: Slurry Pump Systems 37 Slurry Pump Fundamentals

36

Chapter 6:

Slurry Pump Systems

Overview

Once the operating conditions have been selected, pump selection amounts to determining the specific performance of each available pump for the head and flow required and selecting the best pump suited for the duty. Pumps must be selected by matching their head/flow performance to the requirements of the piping systems as explained in Chapter 5.

The largest energy savings are made through the design and control of the pump system. Unfortunately, pumps are too frequently oversized because of uncertainty over future plant expansion and system characteristics.

Never overestimate the system resistance. Doing so results in a greater flow and a higher power consumption. You also risk overloading the motor and experiencing cavitation, high wear or gland problems. Always use the best estimate of system head. Add safety margins to the calculated power only.

Pipe Systems

The pump provides flow and develops hydraulic pressure (head) to over-come the differential in head between two points in pumping systems. This total head differential consists of pressure head, static head, velocity head and total friction head produced by friction between the slurry and the pipe, bends and fittings.

Use head instead of pressure to measure a centrifugal pump’s energy because the pressure from a pump changes if the specific gravity (weight) of the liquid changes, but the head won’t.

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The head of a pump in metric units can be expressed as:

h = (p₂ - p₁) / ( g) + v₂2_{/ (2 g)}

h = total head developed (m)(metric units) p₂= pressure at outlet (N/m2₎

p₁= pressure at inlet (N/m2₎

p = density (kg/m3₎

g = acceleration of gravity (9,81) m/s2₎

v₂= velocity at outlet (m/s)

Pump flange conditions are unknown, so select one point on each side of the pump where you know the conditions and then allow for pipe work losses between these points and the flanges to determine the total head at the flanges.

Friction Losses

The resistance to flow as a liquid moves through a pipe results in a loss of head and is called friction.

STRAIGHT PIPES

The friction loss in a straight pipe varies with: • Pipe diameter

• Pipe length

• Material (roughness) • Flow rate (velocity) To determine friction loss: • Look it up in a table.

• Extract it from a Moody diagram.

• Calculate from a semi-empirical formula such as the William and Hazen Formula.

• Use Slysel, GIW’s pump selection program. (See the end of this chapter for more information.)

your pump by adding a safety factor to the head. Oversizing can result in unnecessary capital expense and untold start-up costs. Instead, apply the factor to the power required by the pump.

Never oversize

Head is measured in feet or meters and can be converted to common units for pressure as psi or bar.

Pumps will pump all fluids to the same height if the shaft is turning at the same rpm. The only difference between the fluids is the amount of power it takes to get the shaft to the proper rpm. The higher the specific gravity of the fluid, the more power is required.

The total friction head is the most difficult to determine because of the com-plex, nonlinear nature of the friction loss curve. This curve can be affected by many factors.

A pump’s vertical discharge pressure head is the vertical lift in height. It’s usually measured in feet or meters of water at which a pump can no longer exert enough pressure to move water.

If the discharge of a centrifugal pump is pointed straight up into the air, the fluid pumps to a certain height or head. This is called the shut off head. In the flow curve chart for a pump, the shut-off head is the point on the graph where the flow rate is zero.

This maximum head is mainly determined by the outside diameter of the pump’s impeller and the speed of the rotating shaft. The head changes as the capacity of the pump is altered.

d a e H p m u P f o s e p y T d a e H c i m a n y D l a t o T Totalheadwhenthepumpisrunning. d a e H c i t a t S l a t o T Totalheadwhenthepumpisn'trunning. d a e H n o i t c u S c i t a t S Headonthesuctionsidewithpumpoffiftheheadis . r e l l e p m i p m u p e h t n a h t r e h g i h t f i L n o i t c u S c i t a t S Headonthesuctionsidewithpumpoffiftheheadis . r e l l e p m i p m u p e h t n a h t r e w o l d a e H e g r a h c s i D c i t a t S Headondischargesideofpumpwiththepumpoff. t f i L / d a e H n o i t c u S c i m a n y D Headonsuctionsideofpumpwithpumpon. d a e H e g r a h c s i D c i m a n y D Headondischargesideofpumpwithpumpon.

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FITTINGS

When a system includes valves and fittings, an allowance for additional friction is necessary, because the fittings can add a significant amount to the total dynamic head that must be produced by the pump.

Total Equivalent Length (TEL) is the most common method for calculating an allowance for additional friction. It can be used for liquids other than water. The fitting is treated as a length of straight pipe giving equivalent resistance to flow.

TEL = Straight pipe length + equivalent length of all pipe fittings SLURRY EFFECTS ON FRICTION LOSSES

Friction losses are also impacted by slurries because they behave differently than clear water. Slurries must be classified as either settling or non-settling (viscous). As a rule of thumb, slurries with particle size < 50 micron are treated as non-settling.

FRICTION LOSSES IN SETTLING SLURRIES

The calculation of friction losses for settling slurries is very involved and best accomplished using computer software such as Slysel. For short runs of pipe at higher velocities, head loss can be taken as equal to the water loss. When calculating the pipe friction losses for slurry, allow for a certain in-crease when compared with the losses for clear water. Assume the suspension will behave like water for concentrations of around 15 percent by volume. At low velocities, head loss is difficult to predict and there is a real risk of solids settling out and blocking the pipe. The minimum velocity nomogram provides a safe minimum velocity. (A nomogram is a chart representing numerical relationships.)

See Chapter 5: Heterogeneous Slurry Flow in Horizontal Pipes in “Slurry Transport Using Centrifugal Pumps.”

FRICTION LOSSES IN NON-SETTLING SLURRIES

We highly recommend that you calculate the friction loss of non-settling slurries with the aid of computer software such as Slysel. Manual assessments can be difficult with all the associated variables.

It is very important that all of the losses in a slurry system be calculated in the best way possible. This provides the correct head and capacity. It also enables the pump to balance the total system resistance and to operate at the correct duty point.

Viscosity

Pull the trigger on a water pistol and the water squirts out. Pull the trigger harder and the water squirts out faster. Fluids resist flow. This phenomenon is known as viscosity. Viscosity is a measure of the thickness of the liquid. Think of it as a slurry’s ability to flow.

Molasses and motor oil are thick or high viscosity liquids. Gasoline and water are thin or low viscosity liquids. Viscosity discussions generally includes two types of liquid: Newtonian and non-Newtonian.

NEWTONIAN AND NON-NEWTONIAN LIQUIDS Newton devised a simple model for fluid flow to demonstrate how hard you have to pull the trigger to how fast the liquid will squirt out of the pistol. Frederick A. Senese, an associate professor in the Department of Chem-istry at Frostburg State University in Maryland, explains it this way on General Chemistry Online:

Picture a flowing liquid as a series of layers of liquid slid-ing past each other. The resistance to flow arises because of the friction between these layers. If you want one layer to slide over another twice as fast as before, you’ll have to over-come a resisting force that’s twice as great, Newton said. The slower one layer slides over another, the less resistance there is, so if

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42

OTHER NON-NEWTONIAN FLUIDS

There are other fluids in which the shear stress is not linear with shear rate. Dilatant fluids, such as paper pulp, increase in viscosity with energy input. Pseudo-plastic fluids, such as mayonnaise or paint, decrease in viscosity with energy input.

Sump Arrangements

Poor sump design is often the largest contributing factor to inadequate pump performance. Most pump malfunctioning can be attributed to the suction side of any pump installation. For best results include the following in the design:

• Sump feed should be below the liquid surface to avoid air entrain-ment. This is especially important with frothy slurries.

• Sump connection to the slurry pump should be as short as possible. A basic rule is five times the pump diameter in length and the same size as the pump inlet.

• Suction pipe should never be smaller than the suction flange of the pumps and should be one size larger to accommodate settling velocity. • Drain connection should be included on the inlet pipe. Use a floor

channel under the drain to recover the slurry. • A reinforced, flexible inlet connection is recom-mended for a possible vacuum condition. • Include a full

bore shut off valve.

Two or more pumps can be operated in parallel when required flow can’t be achieved with a single pump. there wasn’t a difference between the speeds the layers were

mov-ing, there would be no resistance. Fluids, like water and gasoline, behave according to Newton’s model and are called Newtonian fluids.

But ketchup, blood, yogurt, gravy, pie fillings, mud and cornstarch paste don’t follow the model. They’re non-Newtonian fluids, be-cause doubling the speed that the layers slide past each other doesn’t double the

resist-ing force. It may less than double (like ketchup) or it may more than double (as in the case of gravy). That’s why gravy thick-ens as it’s stirred and why struggling in quicksand makes it harder to escape. For some fluids such as mud or snow, you can push and get no flow at all—until you push hard enough and the substance begins to flow like a normal liquid. This is what causes mud slides and avalanches.

Most high-concentration, fine particle slurries are non-Newtonian and have plastic behavior. Plastic means that

energy must be put into the slurry to start it to flow.

To establish friction losses or effects on pump performance for plastic slurries, the true plastic dynamic viscosity and the energy level (yield stress) for the float point must be verified. GIW can provide test work to verify these pa-rameters.

Two or more pumps can be operated in a series when required head can’t be reached with a single pump.

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Chapter 7: Best Efficiency Point 45 Slurry Pump Fundamentals

44

Chapter 7:

Best Efficiency Point

Optimal Efficiency

The efficiency of the pump and its components is one of the factors that affects a pumping system’s performance, and optimizing a pumping system’s efficiency can result in up to a 60 percent reduction in energy and mainte-nance costs. But, in the real world, pumps are seldom operated at their Best Efficiency Point (BEP).

BEP, in technical terms, is the point where the brake horsepower going into the pump is the closest to the water horsepower coming out of the pump. It’s at this point where the pump has the least amount of shaft vibration and deflection.

Pump efficiency can decrease significantly when the pump operates away from the its BEP. Over-specifying the duty when selecting a pump increases energy costs.

In this chapter, we look at reasons pumps don’t operate at BEP.

See Chapter 13, Practical Experience with Slurry Systems in “Slurry Transport Using Centrifugal Pumps.”

Radial Load

The radial direction is 90 degrees or at a right angles to the centerline of the shaft.

• Separate sumps are preferred for standby pump installations. This avoids settling in the standby pump sump when not in use.

Multiple Pump Installations

Two reasons for using multiple installations of slurry pumps are: 1. When the head is too high for a single pump.

2. When the flow is too great for a single pump. PUMPS IN A SERIES

When required head can’t be reached with a single pump, two or more pumps can be operated in a series. This application is used often to meet the high head required in long-distance tailings or to reduce the head of a single-stage pump in a demanding mill circuit application. Series operation allows a lower operating speed, which results in reduced wear.

The discharge from the first-stage pump is connected directly to the second pump. This doubles the head produced. Two identical pumps in a series provide the same system efficiency as the individual pumps.

PUMPS IN PARALLEL

When required flow can’t be achieved with a single pump, two or more pumps can be operated in parallel. The discharge from both pumps is con-nected to the same line. Parallel pumps must be identical. Parallel pumping for slurry is uncommon.

Slysel

Slysel, GIW’s proprietary pump selection program, is easy to use and aids in all aspects of pump selection. It’s free for GIW customers. Slysel:

• Calculates performance curves.

• Evaluates slurry and horizontal friction. • Calculates overall pipeline system resistance. • Selects or evaluates pumps.

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• Use pump out vanes or radial ribs on the back of the impeller to reduce the pressure behind the impeller.

• Use a hydraulic balancing device mounted in a chamber connected to the suction side of the pump or a low point in the system as some multi-stage pumps do.

Shaft Deflection

A number of forces act on the shaft to cause it to deflect including: • Forces causing rotation (torque) of the shaft

• The weight of the parts

• Radial and axial hydraulic forces • Vibration

The deflection can be along the length of the shaft (axial) or 90 degrees to the length of the shaft (radial).

Here are suggestions to help reduce the deflection caused by operating off the BEP:

• Go to a larger diameter shaft replacing the mechanical end with a larger unit.

• A variable speed motor makes sense if the pump’s primary head is friction head.

• Tell the operator to operate the pump at its BEP. (Good luck with that one!)

Water Hammer

Water hammer is a destructive pressure surge that takes place in piping systems when the rate of flow changes suddenly. This is of greater signifi-cance in low head pumping systems than in high head systems.

There are multiple causes for this change in rate of flow including: The radial bearing supports the shaft from defection caused by impeller or

drive loads. There are multiple causes of a radial deflection of the shaft, including:

• A non-concentric shaft sleeve

• Pipe loads at the pump flange, either physical or thermal

• Operating off the BEP causes the shaft to deflect in a radial direction. • Dynamic unbalance of the rotating assembly changes as the impeller

wears.

• The pump and driver are misaligned. The coupling may not compen-sate for this.

• Vibration causes radial deflection. Vibration includes cavitation and water hammer.

See Chapter 5 for information on cavitation. Water hammer is discussed at the end of this chapter.

Axial Load

Axial movement is movement along the length of the shaft. The thrust bear-ing resists movement axially and transfers this force from the shaft to the housing.

The pressures generated inside a centrifugal pump work on both the station-ary and rotating components.

On single-inlet impellers, an axial force exists because of differences in pres-sure on the front and back of the impeller and the difference in the areas subject to the pressure. Axial thrust is the sum of these unbalanced forces acting in an axial direction.

Several ways to compensate for axial thrust are:

• Install a double-row thrust bearing in the end of the casing next to the coupling.

• Install a wear ring on the back of the impeller with holes drilled through the impeller to equalize some of the forces.

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• The power to the pump is lost for some reason and the pump slows down faster than the fluid flowing in the lines and liquid separation takes place.

• Small pipe sizes can cause rapid velocity changes. • A valve closes rapidly in the suction line.

• Surge tanks and air chambers can protect some piping systems from the affects of water hammer.

See Chapter 13, Section 13.6 Water Hammer in “Slurry Transport Using Centrifugal Pumps.”

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Chapter 8: Technical Descriptions 51 Slurry Pump Fundamentals

50

LCC Hard Metal Series pumps are suitable for high discharge head, mildly corrosive slurries and a wide range of particle sizes.

Chapter 8:

Technical Descriptions

A number of factors affect GIW’s slurry pump design including:

• Certified performance by hydraulic testing in GIW’s Hydraulic Testing Laboratory, the largest lab of its kind in the world

• Computer-generated, cutting-edge hydraulic designs for high effi-ciency and maximum wear life

• Innovative wear materials, such as GIW Gasite®_{white iron, for longer}

parts wear life

• Linatex®_{rubber liners, a superior wear product compared to any other}

natural rubber in today’s market

• Special design features, such as a split stuffing box, to reduce mainte-nance down time

• Designs with optional mechanical seal or expeller

Metal Pumps

LCC HARD METAL SERIES (LCC-M) The LCC hard metal slurry pump is a horizontal, end suction, centrifugal slurry pump.

The hydraulic wet end consists of three components: a shell or casing, an impeller and a suction plate/liner to permit easy removal for mainte-nance and inspections.

The LCC-M slurry pump does not require a separate outer housing.

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• The standard fused carbide-coated shaft sleeve provides a smooth, extremely hard surface for long packing life. Optional sleeve materials are available.

Application

LSA-S slurry pumps are widely used in ore transport, mill discharge, cyclone feed, tailings and plant process. The LSA can also be found in environmental cleanup, dewatering (low head type), pulp and paper (liquor transfer), food processing (sugar and sugar beets), coke and resin pumping and ash han-dling.

Size Range

• Discharge diameters: 2 - 26 in. (50 - 600 mm)

• Flows: 100 - 60,000 gpm (22 - 13600 m3_{/h) (Contact GIW for higher}

flow needs.)

• Total head to 300 ft./stage (91 m) • Capabilities to 2,500 hp (1862kW)

• Special high-pressure design up to 900 psi (62 bar) test available

Rubber Pumps

LCC RUBBER-LINED SERIES (LCC-R)

The LCC pump design incorporates state-of-the-art hydraulic design and wear materials for heavy-duty

appli-cations. LCC pumps provide a low total cost of ownership.

The series offer two pedestal sizes, which cover the entire range of seven wet end sizes to maximize system flexibility and reduce inventory. Interchangeable rubber and metal designs enable you to make the best material choice for any application. Easy wet end change can adapt existing pumps to new applications. LCC’s are available with either oil or grease lubrication.

LCC-R slurry pumps are suitable for moderate discharge head, fine particles and highly corrosive slurries.

Features

• A horizontal shaft • A single-wall shell

• A three-vane impeller and a suction plate/liner of high-chrome white iron for long, predictable wear life

Application

The pumps are suitable for high discharge head, mildly corrosive slurries and a wide range of particle sizes. Custom materials are available for highly corrosive slurries.

Size Range

• Discharge diameters: 2 - 12 in. (50 - 300 mm) • Flows to 17,000 gpm (3865 m3_/h)

• Total head to 300 ft. (90 m) • Capabilities to 700 hp (520 kW)

• Shaft sizes from 1.5 - 5 in. (35 - 125 mm) LSA-S SERIES

Pumps in the highly efficient LSA-S LSA-Series are primarily for heavy-duty service in a wide variety of slurry applications. The pump’s rugged design and wet end parts are made from proprietary GIW Gasite®_{material, which is}

recog-nized worldwide for superior abrasion resistance and excellent performance. Optional impeller designs can fine tune pump perfor-mance to meet your specific sys-tem needs.

Features

• The heavy-duty, split-cartridge bearing assembly with spherical roller radial bearings and steep angle, self-aligning thrust bearing ensures maximum efficiency and minimum shaft deflection.

LSA-S slurry pumps are widely used in ore transport, mill discharge, cyclone feed, tailings and plant process.

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• LSR pumps are lined with Linatex®_{rubber, a superior wear product}

compared to any other natural rubber in today’s market.

• The LSR holds its original operating efficiency rating longer than any of its competitors.

Application

Designed for heavy-duty mill circuit and fine grind slurries.

Size Range

• Total head to 200 ft. (60 m) • Shaft sizes: 5 - 6 in. (125 - 175 mm)

Vertical Pumps

VERTICAL

GIW heavy-duty vertical pumps are the answer for the most aggressive corrosive and abrasive slurry applications. These rugged pumps com-bine long wear life with high sustainable hy-draulic efficiency for the lowest total cost of ownership.

Features

• Wear components are available in a wide range of proprietary hard iron alloys along with rubber and urethane casing liners to meet any application.

• The v-belt drive system accepts high horsepower motors and the structural parts can be ordered in corrosion resis-tant alloys.

• Performance and efficiency, plus easy maintenance, provide the best value with a GIW vertical slurry pump.

The LCV Series is ideal for industrial process pumping, tailings disposal in mining and pit use for dredge and other operations.

The LSR is designed for heavy-duty mill circuit and fine grind slurries.

Features

• The LCC Rubber-Lined Series features a split casing design with molded, replaceable rubber liners.

• The LCC rubber pump is fitted with a Linatex®_{rubber liner. Linatex is}

a superior wear product compared to any other natural rubber in today’s market.

• Liners may be specified in a variety of natural and synthetic rubbers to meet specific slurry applications

• The liners are vulcanized to metal backing plates and captured at the split casing, suction discharge flanges and stuffing box area to main-tain hydraulic and hydrostatic integrity.

Application

LCC-R slurry pumps are suitable for moderate discharge head, fine particles and highly corrosive slurries.

Size Range

• Total head to 300 ft. (90 m) • Capabilities to 700 hp (520 kW) • Shaft sizes: 1.5 - 5 in. (35 - 125 mm) LSR

With the addition of the LSR, GIW now offers a solution for all of your slurry pumping needs. The LSR is built to operate at the lowest total cost of ownership with its superior hy-draulic design.

Features

• Double-wall construction with an outer ductile iron casing and inner molded rubber liners

• Three-vane impellers cast of hard metal or polyurethane

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• Total head to 260 ft. (80 m)

• Capabilities up to 4,000 hp (2980 kW) • Hydrostatic tested up to 600 psi TBC

These pumps are constructed as horizontal, end suction centrifugal pumps to give maximum resistance to wear while simplifying maintenance. The con-ventional single-wall design transfers stress loads to non-wearing side plates in high-pressure applications.

Features

• Impeller and casing hydraulics are designed with proprietary GIW computer programs for high efficiency, maximum suction perfor-mance and large solids passage.

• Standard bearing assemblies feature an integrated Bearing Isolator System. Designed by GIW, it consists of a labyrinth seal machined into the end cover and covered with an elastomer v-ring and metal flinger. This double seal excludes contaminants.

• Forward flush stuffing box comes standard on TBCs. • Oil lubrication is

standard. GIW’s Blue 150 synthetic oil is included for the initial fill. • Optional oil

recircu-lation and powered coolers are available options for large units.

Applications

TBC pumps feature high head and high flow rates for dredging, pipeline booster stations and other severe duties.

Applications

The LCV Series is ideal for industrial process pumping, tailings disposal in mining and pit use for dredge and other operations.

Size Range

• Discharge sizes: 2 - 12 in. (50 - 300 mm) • Flows to 6000 gpm (1360 m3/h) • Total head up to 125 ft. (38 m) • Shaft sizes: 3.5 - 8 in. (90 - 200 mm) • Cantilevers: 35 - 71 in. (900 - 1800 mm)

High-Pressure, Multi-Stage Slurry pumps

WBC

The patented design of the WBC slurry pump incorporates state-of-the art hydraulic wear technologies for severe-duty, high-pressure applications. The pump shell is designed to reduce bending movements and associated stresses that can cause a structural failure during a pressure surge.

Features

• The shell, impeller and suction liner are made of GIW Gasite®

alloys, which are recognized for superior abrasion resistance. • Three-vane impellers offer maximum particle size passage. • The pump is equipped with GIW’s proven heavy-duty mechanical

end with spherical roller radial bearings and separate steep-angle thrust bearing.

• The standard fused carbide-coated shaft provides a smooth, ex-tremely hard surface for long packing life. Optional sleeve materi-als are available.

Applications

Primary services are in ore and tailings transport lines subject to sudden pressure spikes.

Size Range

• Discharge diameter: 18 - 26 in. (460 - 660 mm) • Impeller diameters: 46 - 54 in. (1168 - 1372 mm) • Flows to 60,000 gpm (13600 m3_{/h )}

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Size Range

• Discharge diameters: 12 - 44 in. (305 - 1118 mm) • Flows: 5,000 - 140,000 gpm (1136 - 31900 m3_/h)

• Total head to 300 ft.+/stage (91 m) • Capabilities beyond 12,000 hp (8940 kW)

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Chapter 9: Application Guides 61 Slurry Pump Fundamentals

60

Chapter 9:

Application Guide

Selection by Duty

Slurry pumps are often selected based on the duty or the type of slurry being pumped. A thorough knowledge of the application is needed to select the right pump for the application and to reduce wear on the pump.

When selecting by duty, consider the:

• Size, shape and density of the solids being pumped • Head requirements

• Type of liquid

Use the following guidelines when selecting your pump by duty:

COARSE PARTICLES

• Any solid larger than 12 in. (300 mm) • Metal pumps (Never use rubber.) • Upper limit solid size is 2 in. (50 mm). • The impact on the impeller is the limitation.

Recommendation: LSA, WBC, TBC

FINE PARTICLES

• Use rubber for sharp particles.

• If particles are not sharp, rubber or metal is fine.

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62

HIGH SUCTION LIFT

• Metal pumps are preferred, because of the risk of a rubber lining collapse on high suction lifts.

• Maximum practical suction lift 10 - 12 ft. (3 – 3.5 m), depending on specific gravity

• Priming device required.

• Pump and inlet pipe must be filled with liquid before starting up the pump.

Recommendation: All series

HIGH FLOW

• Use parallel pumps installations. (See “Chapter 6, Slurry Pump Sys-tems.”)

• Increased cavitation risk

LOW FLOW

• Use metal to avoid overheating rubber linings.

Recommendation: LHD

FLUCTUATING FLOW

• Use horizontal pumps with variable speed drive or fixed speed vertical pumps.

Duties Related to Slurry Type

FRAGILE SLURRIES

• Both metal and rubber pumps can be used. • Both horizontal and vertical pumps can be used.

SHARP (ABRASIVE) PARTICLES

• Use rubber for sizes below .20 in. (5 mm). • Use metal for sizes above .20 in. (5 mm).

HIGH PERCENT SOLIDS

• Solids percentage must be below 50 percent by volume.

LOW PERCENT SOLIDS

• Light-duty pump, high-efficient pump

Recommendation: LCC, LCV

FIBROUS PARTICLES

• Problem with particle and air blocking

Recommendation: LCC or LSA with open shroud impeller

Duties Related to Head and Volume

HIGH HEAD

• High speed/high wear

• Maximum head on metal pump 410 ft. (125 m) • Maximum head on rubber impeller 148 ft. (45 m)

VARYING HEAD AT CONSTANT FLOW

• Use a multi-speed drive or variable drive.

VARYING FLOW AT CONSTANT HEAD • Use variable drives.

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HYDROCARBON SLURRIES (OIL AND REAGENTS CONTAMINATED) • Cannot use natural rubber.

• Use synthetic seals. • Use metal pumps.

HIGH TEMPERATURES ABOVE 212˚F (100˚C) SLURRIES • Cannot use natural rubber.

• Operating limit is 275 F (135 C). Above this, bearings can overheat.

HAZARDOUS SLURRIES • Shaft sealing is critical. • Usually a closed pump system

Recommendation: Horizontal series with mechanical seals

CORROSIVE SLURRIES (LOW PH) • Use Gasite®_T90G.

Recommendation: LCC, LSA

HIGH VISCOSITY FLUIDS (NEWTONIAN)

• Pumping is critical if the viscosity is over five times the viscosity of water.

HIGH VISCOSITY FLUIDS (NON-NEWTONIAN)

• Pump selection is difficult. Please consult your GIW representative.

Selection by Industrial Application

This general guide is provided for reference only. It contains some common slurry pump industrial applications served by GIW slurry pumps.

This is a schematic of phosphate mining, a common slurry pump application.

HARD ROCK MINING

• Grinding circuit pumps • Floor sump pumps • Tailings pumps • Cyclone feed pumps • Tailings pumps

• Thickener overflow pumps • Screen discharge pumps

Fundamentals-REV-5.pdf

An easy-to-understand introduction to

slurry pumps and systems

Reader’s Guide

giwindustries.com

For Our Customers

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Contents

Chapter 1:

What Is Slurry?

Slurry Pumps vs. Water Pumps

Solids Limitations

Flow Limitations

Chapter 2:

Slurry Pumps Defined

Wear Conditions

Wet End

Markets & Applications for Slurry Pumps

Installations

Chapter 3:

Slurry Pump Design &

Components

Basic Designs

Basic Components

Vane Designs

Shell

Impeller

Shaft and Bearings

Drives for Slurry Pumps

Suction Liner

Shaft Seals

Chapter 4:

Wear Protection

Wear

Corbrasion™

Selection of Wear Materials

Elastomer Construction

Ceramic Wear Parts

Corrosion Resistance and Wear Resistance

Wear Resistance Range

pH Ranges

Chapter 5:

Hydraulics

Pumps and Curves

Vapor Pressure and Cavitation

Don’t

Head

Pumping Froth

Chapter 6:

Slurry Pump Systems

Overview

Pipe Systems

Friction Losses

Never oversize

Viscosity

Sump Arrangements

Chapter 7:

Best Efficiency Point

Optimal Efficiency

Radial Load

Multiple Pump Installations

Slysel

Shaft Deflection

Water Hammer

Axial Load

Chapter 8:

Technical Descriptions

Metal Pumps

Rubber Pumps

Vertical Pumps

High-Pressure, Multi-Stage Slurry pumps

Chapter 9:

Application Guide

Selection by Duty

Duties Related to Slurry Type

Duties Related to Head and Volume

Selection by Industrial Application