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WEAR

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Wear in operation

Introduction
Mineral processing activities unavoidably result in wear. And wear costs money. Often lots of money. This is related to the structure of rock, ore or minerals, being crystals normally both hard and abrasive.

Why wear at all?
Wear is caused by the normal rock stress forces • Compression (1) • Impaction (2) • Shearing (3) • Attrition (4) in combination with mineral hardness and energy! 1 2

3

4

Wear in operation caused by
COMPRESSION IMPACTION
HIGH VELOCITY >7m/s

IMPACTION
LOW VELOCITY <7m/s

SLIDING

METALS Manganese Steel Ni hard Ni-Cr white iron High Crome Cr white iron
BASICS IN MINERAL PROCESSING
Chap 09 Wear in operation.p65 1

Polymers Rubber protected by Polyurethane

CERAMICS

Product Handbook 9:1
2002-03-13, 08:58

Wear in operation

Wear in operation

Wear by Compression
COMPRESSION IMPACTION
HIGH VELOCITY >7m/s

IMPACTION
LOW VELOCITY <7m/s

SLIDING

Metals Manganese Steel Ni hard Ni-Cr white iron High Crome Cr white iron

Metals and compression Manganese steel: The first option for compression wear is manganese steel. This alloy has a very special property, being self hardening and self healing when exposed to large amounts of compression and impact energy. Normal standard is a 14% Mn alloy which is first option in most crushing applications. 18 % Mn alloy is a harder but also a more brittle alloy used in applications where the rock is softer (limited self hardening) but very abrasive. Restrictions: When installed in applications without work hardening service life will be poor! The alloys of cast ”white iron” type (High-chrome and Ni- hard) shall be avoided in crushers submitted to heavy compression.

Crushers

Wear by Impaction (high)
COMPRESSION
Wear in operation

Metals Manganese Steel Ni hard Ni-Cr white iron High Crome Cr white iron

Impactors

Grinding Mills Slurry Pumps

9:2 Product Handbook
Chap 09 Wear in operation.p65 2

}

Applications:

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Applications:

Gyratory Cone Jaw

IMPACTION
HIGH VELOCITY >7m/s

IMPACTION
LOW VELOCITY <7m/s

SLIDING

Metals and impaction The metals can be classified as: Manganese: Needs high impaction for self hardening. If impaction is getting lower and sliding is increasing Manganese is not suitable. High Chrome: Opposite to manganese, can take heavy sliding but is more fragile and therefore limited against impaction. Ni-hard: Somewhere between the two materials above. Cr-Mo: Used in grinding when High Crome is too brittle

HSI VSI

Note! The use of chrome steel (less brittle than chrome iron) is increasing for liners, curtains and hammers.

BASICS IN MINERAL PROCESSING
2002-03-13, 08:58

Wear in operation

Wear by Impaction (low)
COMPRESSION IMPACTION
HIGH VELOCITY >7m/s

IMPACTION
LOW VELOCITY <7m/s

SLIDING

Rubber and impaction For low velocity impaction (material speed less than 7 m/s) SBR, styrene butadiene rubber (60 ShA) is always the first choice and will give the best cost effectiveness. The material is also very tolerant to material size and is excellent for use in grinding mills, dump trucks and primary hoppers.

Metals Rubber Polyurethane

Restrictions: Look out for aromatic and fuel oils. Impact angles have to be considered, see 9:4.

CERAMICS
Applications: Dump Trucks, Feeder hoppers, Transfer points, Grinding Mills Slurry pumps

Wear by Sliding
IMPACTION
HIGH VELOCITY >7m/s

COMPRESSION

IMPACTION
LOW VELOCITY <7m/s

SLIDING

Rubber and sliding Natural rubber is an outstanding option for the sliding abrasion of small, hard and sharp particles. Also for wet conditions.

Polymers Rubber
Wear in operation

Restrictions: If sliding speed is exceeding 7 m/s (dry applications) temperature can start to rise and cause damage. Besides temperature oil is always a threat.
Polyurethane and sliding Best option for tough sliding applications when particle size is lower than 50 mm. Excellent in wet applications. Tolerant to chemicals and oil.

Polyurethane

CERAMICS
Applications: Chutes, Spouts

Restrictions: Large sizes and high velocity might cause problems.
Ceramics and sliding The natural choice when mission is too hard for the options above. Hardness, resistance to temperature and corrosion plus low weight gives a masterpiece for sliding. Al203 (Aluminium oxide) is the most cost-effective material.

Restrictions: Impaction is dangerous for ceramics (cracking) and must be avoided. Combination ceramics + rubber is an option. Composition and quality can vary from supplier to supplier.
BASICS IN MINERAL PROCESSING
Chap 09 Wear in operation.p65 3

Product Handbook 9:3
2002-03-13, 08:58

Wear in operation

Wear Protection – Wear Products
Modules
Sheets, elements and profiles Rubber module Polyurethane Ceramic module module

Customized lining systems

Wear in operation

Wear products – applications
HEAVY IMPACT Elements – Rubber IMPACT & SLIDING Square Modules – Rubber – Polyurethane – Ceramic SLIDING & IMPACT Sheeting – Rubber – Polyurethane SLIDING / BUILD UP Low Friction

100 micron

>1000 >500 >100 >80

64

32

22

16

11

8

4

0 Size mm

9:4 Product Handbook
Chap 09 Wear in operation.p65 4

BASICS IN MINERAL PROCESSING
2002-03-13, 08:59

Wear in operation

Heavy Impact – Selection
Size / Weight

Drop Height

&

Truck Box
Thickness

=

Primary Feeder Hopper

Rubber 60 Sh Steel Backing
100 micron

>1000 >500 >100 >80

64

32

22

16

11

8

4

0 Size mm

Impact and Sliding – Selection (modules)
Size / Weight

Drop Height

& & &

Impact angle

Capacity
Ceram Pu Ru
100 micron

NG LD UP

>1000 >500 >100 >80

64

32

22

16

11

8

4

0 Size mm

BASICS IN MINERAL PROCESSING
Chap 09 Wear in operation.p65 5

Product Handbook 9:5
2002-03-13, 08:59

Wear in operation

Wear in operation

Impact and sliding – Selection (sheeting)
Size / Weight

Drop Height

& & &

Impact angle

Capacity

=
100 micron
>1000 >500 >100 >80 64 32 22 16 11 8 4

Thickness

0 Size mm

Sliding and build up – selection
Low Friction Elements – UHMWPE*
*Ultra high Molecule Weight Poly Ethylene

MATERIAL mm <20 <35
Wear in operation

THICKNESS mm 3 - 10 10 - 25 25 - 40

<70

100 micron

>1000 >500 >100 >80

64

32

22

16

11

8

4

0 Size mm

9:6 Product Handbook
Chap 09 Wear in operation.p65 6

BASICS IN MINERAL PROCESSING
2002-03-13, 08:59

Wear in operation

Wear Protection – Wear Parts
Wear parts – Screening
Self supporting rubber panels Rubber & polyurethane tension mats Rubber & polyurethane bolt down panels

Antiblinding rubber mats

Rubber / polyurethane modular systems

Wear parts – Grinding
Rubber linings Poly-MetTM linings OrebedTM linings

Steel linings

Discharge systems

Trommel screens

BASICS IN MINERAL PROCESSING
Chap 09 Wear in operation.p65 7

Product Handbook 9:7
2002-03-13, 08:59

Wear in operation

Wear in operation
Tumbling mill – lining components
1. 2. 3. 4. 5.

6.

7.

8.

9.

10.

Lining life time – Standard Linings “ball park figures” Type of mill AG SAG Rod Ball Pebble Months 12 – 24 3 – 12 6 – 24 6 – 36 12 – 48

Lifter bars – rubber and compound
Rubber
Regrind and Pebble Mills

Poly-Met HiCr HB 700

Poly-Met HiCr HB 700

Poly-Met Martensitic steel HB 500

Owerflow Ball and Rod Mills

Wear in operation

Secondary Ball Mills

Autogenous and Semi-autogenous Mills

Primary Ball Mills






lower speeds


higher speeds

Semi Autogenous Mills

lower speeds

Autogenous Mills

Rod Mills


higher speeds

 = mill rotation

9:8 Product Handbook
Chap 09 Wear in operation.p65 8

BASICS IN MINERAL PROCESSING
2002-03-13, 09:00

Wear in operation
Tumbling mill liners– material
AG and SAG mills Rod mills

Dry: Metal (white iron 700 Br) Wet: Metal (white iron 700 Br) or Poly Met (700 Br)

Dry: Metal (Cr-Mo 350 Br) Wet: Metal (Cr-Mo 350 Br) or Poly Met (500 Br)

Dry: Metal (white iron 700 Br) Wet: Metal (white iron 700 Br) Rubber and Poly Met, (Poly Met at mill ends)

Ball and Pebble mills

SRR mills

Dry: Metal (or rubber if temperature not critical) Wet: Rubber (Secondary and regrind) Poly Met (700 Br)

Dry-rod: Metal Dry-ball: Metal (or rubber if temperature not critical) Wet-rod: Metal
Wear in operation

Wet-ball: Rubber

VERTIMILL® – Liners
Screw – metal with Nihard liners Chamber – Orebed magnetic liner

BASICS IN MINERAL PROCESSING
Chap 09 Wear in operation.p65 9

Product Handbook 9:9
2002-03-13, 09:00

Wear in operation

Wear parts – Slurry Pumps
Although the size of solids in a slurry is smaller than the feed size to a crusher or a grinding mill, wear represents a high operation cost for slurry pumping. This is naturally related to the high dynamic energy input in the form of high tip speed of the pump impeller causing both sliding and impaction wear.

Wear material vs size

LIMIT FOR HYDRAULIC TRANSPORT

HIGH CHROME

Size

1m

1 dm

LIMIT FOR RUBBER LINERS

MANGANESE STEEL
LIMIT FOR HARD IRONS

1 cm

LIMIT FOR RUBBER IMPELLERS

Wear in operation

1 mm

100 micron

10 micron

1 micron

Wear parts pumps –metal
High chrome iron (600Br) can be used at Ph down to 2.5. Standard wear material for most pump ranges. Ni –hard with hardness exceeding 600 Bn used mainly as casing material for pumps in grinding circuits or dredging. High density frozen Ni-hard with hardness up to 900 Bn used as casing material in primary grinding circuits. Manganese steel with hardness up to 350 Bn used for dredging applications.

9:10 Product Handbook
Chap 09 Wear in operation.p65 10

BASICS IN MINERAL PROCESSING
2002-03-13, 09:01

Wear in operation
Wear parts pumps – elastomers

Material

Physical properties

Chemical properties

Thermal properties
Highest service temp.( oC) Contin. Occasion. (-50) to 65 90 100 100 45-50 100 120 130 130 65

Max. Wear Hot water, Strong and Oils, Impeller Tip resistance diluted acids oxidising hydro Speed acids carbons (m/s) Elasta family (Natural rubber) MeroPrene 452 (Chloroprene type) MeroLen 016 (EPDM type) MeroTyle (Butyl type) MeroThane Polyurethane 30 Very good Fair Bad Good 30 Fair Excellent Good Bad 30 Good Excellent Good Bad 27 Good Excellent Fair Good 27 Very good Excellent Fair Bad

Something About Ceramic Liners
Although ceramics have high resistance against wear, temperature and most chemicals, they have never really been accepted as day-to-day standards in Slurry Pumping. Being both brittle and expensive to manufacture. Development work on ceramics continue in an attempt to improve the possible acceptance.

micron

BASICS IN MINERAL PROCESSING
Chap 09 Wear in operation.p65 11

Product Handbook 9:11
2002-03-13, 09:01

Wear in operation

Wear in operation

Wear in Slurry Pipelines
It is not easy to compare wear rates for different materials in a slurry pipeline depending on variations in duty. As a guide the figures below can be used (British Steel Corporation test report). Average wear rates given as loss of material in mm³ per hour at a given speed and slurry composition. Material Average wear rate Polyurethane Rubber Stainless steel Alumina (97.5%Al2O3) Cast iron (2.8% C, 2.0%Cr, 3.8%Ni) Polyethylene API steel Mild steel PVC 0,024 0,033 0,056 0,070 0,287 0,353 0,396 0,456 0,880 Relative wear rate (months) 19,0 13,8 8,1 6,5 1,6 1,3 1,2 1,0 0,5

Wear in operation

9:12 Product Handbook
Chap 09 Wear in operation.p65 12

BASICS IN MINERAL PROCESSING
2002-03-13, 09:01

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