Doralox® 92W

CERAMIC BALL MILL LINING BRICKS AND GRINDING MEDIA

Duralox is a registered brand name of a specially developed proprietary composite by Jyoti Ceramic from which ball mill lining bricks, wear resistant lining tiles, grinding media and other components are manufactured.

The true value of ball mill lining is determined by its length of trouble free service in relation to the mill’s production output, irrespective of mill’s type, size and shape. The criteria for selection of lining and grinding material must take into consideration not only the required output and expected service life, but also construction of ball mill, it’s drive and motor power before switching over to materials of high density such as Duralox.

Duralox 92W mill lining bricks and grinding media have been developed by Jyoti Ceramic after many years of R & D with the intention of enhancing the former’s performance. Duralox 92W lining bricks and Duralox 92W grinding media complement each other’s performance and best results are obtained when both are used together..

PHYSICAL PROPERTIES
Colour White
Surface finish
Density 3.70 ± 0.05 g/cm3
Bulk Density 2.1 ± 0.05 kgs/lt
Water Absorption 0.00
Flexural Strength
(@ room temp.)
320 MPa
Compressive Strength
(@ room temp.)
2000 MPa
Hardness on Moh’s scale 9+
Hardness on Vicker’s scale 1300 Hv5
Safe operating temperature 1400 ℃
Co-efficient of Thermal Expansion (25℃ to 1000℃) 7.6 x 10−6/ ℃
Chemical Properties
Al2O3 92.30%
SiO2 2.55%
MgO 2.45%
CaO 2.10%
Na2 O 0.30%
BaO 0.15%
Fe2 O3 0.05%
TiO2 0.10%
* Duralox® 92W is resistant to all acids and alkalis except Hydrofluoric Acid

Versatile Industrial Applications

Duralox® 92W

TAPERED AND FLAT MILL LINING BRICKS

Duralox ceramic mill lining bricks protect the steel ball mill shell and provide high purity grinding. Following features and benefits are worth considering while using Duralox Ball Mill linings for milling substances of hardness below 9.0 Moh’s scale :

  • Chemically inert and non - reactive to chemicals except Hydrofluaric acid.
  • Wear rate of lining is negligible and more constant as compared to traditional ceramic lining materials. With tongue and groove design it produces an interlocking lining pattern, which holds the bricks inseparably
  • Dimensional stability : Duralox ceramic mill lining bricks are uniform and stable in dimensions. With controlled dimensions and sharp edges, requirement of adhesive/cment for fixing and filling of narrow joints is minimum, which prevent bricks from chipping and spalling of their edges
  • Easy to install : installation of Duralox lining in a ball mill can be carried out easily and speedily by any skilled or semiskilled mason under supervision of civil / mechanical engineer
  • Duralox mill linings have excellent service life under normal working conditions, Duralox mill linings last about 12-15 times longer than steel, rubber etc. and 25 to 30 times longer than stone and other conventional ceramic lining materials.
  • Substantial increase in mill volume due to lesser thickness as compared to traditional stone lining. A strong thin Duralox ceramic lining brick increases the working volume in a mill than thick natural stone lining blocks. A 1800mm dia. x 1800mm L Ball Mill a 50 mm thick Duralox brick lining will increase mill working volume by 30% as compared to the 125mm thick conventional natural stone lining blocks.
  • Hard and tough, resists high impact, high abrasion and corrosion wear
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To calculate lining for a cylindrical mill (flanges are lined first and feed door opening are not considered ) formulae to be used are :

1. Straight bricks for flanges


where: N1 = Number of straight bricks

a1 = Length of straight brick in cms

b1 = width of straight brick in cms

D = Internal diameter of mill in cms

2. Tapered bricks of cylindrical face


where: N2 = Number of tapered bricks

a2 = Length of tapered brick in cm

b2 = width of tapered brick in cm

D = Internal diameter of mill in cm

L = Internal length of the mill after lining in cm

Example : To calculate the number of bricks required for Dia 6' X 6' Long (Dia 180cm X 180 cm Length) cylindrical ball mill (flangs are lined first)

Here: a1 = a2 = 150 mm = 15 cm

b1 = b2 = 50 mm = 5cm

D = 180 cm

L = 170 cm

Therefore:

Dimensions and Weights of Standard Size Mill Lining Bricks

Brick Number Dimension in mm weights in kgs
H W L
ALCM-150-100 50 100 150 2.775
ALCM-75-100 50 100 75 1.387
Brick Number Dimension in mm weights in kgs
H W L
ALF-150-25 25 25 150 0.348
ALF-115-25 25 25 115 0.265
ALF-75-25 25 25 75 0.173
ALF-35-25 25 25 35 0.08
ALF-150-40 40 40 150 0.888
ALF-115-40 40 40 115 0.68
ALF-75-40 40 40 75 0.444
ALF-35-40 40 40 34 0.207
ALF-150-50 50 50 84 1.388
ALF-115-50 50 50 115 1.05
ALF-75-50 50 50 75 0.67
ALF-35-50 50 50 35 0.323
ALF-150-65 65 62 150 2.219
ALF-115-65 65 62 115 1.715
ALF-75-65 65 62 75 1.118
ALF-35-65 65 62 35 0.522
ALF-150-75 75 62 150 2.58
ALF-115-75 75 62 115 1.978
ALF-75-75 75 62 75 1.29
ALF-35-75 75 62 35 0.602
Brick Number Dimension in mm weights in kgs
H W1 W2 L
ALT-150-27 25 32 27 150 0.410
ALT-115-27 25 32 27 115 0.314
ALT-75-27 25 32 27 75 0.204
ALT-35-27 25 32 27 35 0.096
ALT-150-33 40 40 33 150 0.812
ALT-115-33 40 40 33 115 0.621
ALT-75-33 40 40 33 75 0.405
ALT-35-33 40 40 33 35 0.189
ALT-150-50 50 56 50 150 1.448
ALT-115-50 50 56 50 115 1.11
ALT-75-50 50 56 50 75 0.67
ALT-35-50 50 56 50 35 0.343
ALT-150-53 50 6 53 150 1.517
ALT-115-53 50 56 53 115 1.159
ALT-75-53 50 56 53 75 0.74
ALT-35-53 50 56 53 35 0.352
ALT-150-58 65 62 58 150 2.16
ALT-115-58 65 62 58 115 1.66
ALT-75-58 65 62 58 75 1.083
ALT-35-58 65 62 58 35 0.505
ALT-150-57 75 62 57 150 2.48
ALT-115-57 75 62 57 115 1.9
ALT-75-57 75 62 57 75 1.24
ALT-35-57 75 62 57 35 0.59

Dimensional tolrances ± 0.5 mm or 2.0% whichever is greater, Bow allowance maximum 0.5% of length.

Duralox Brick Lining Installation made customer friendly

With over 5 decades of manufacturing experience in technical ceramics coupled with modern manufacturing facilities, we at Jyoti Ceramic offer CAD/CAM designed, custom engineered mill lining brick sets, to fit ball mills without requiring any cutting, chipping or grinding of bricks at customer’s end. Duralox ceramic lining bricks are sapphire hard and therefore, most difficult to cut, chip, grind to the shape or size after sintering. Our suggestion to our esteemed customers is to select plant engineered lining bricks which are machined as per ball mill dimensions.

To manufacture pre-engineered mill lining, all our engineers require is a copy of the mill drawing showing precise inner dimensions of the mill shell, door, lid and frame to design the correct size lining bricks for your mills. Duralox 92W lining bricks fit close and tight in the mills as they are match marked in the pre-sintered stage itself, taking into account allowance for shrinkage during sintering. These mill lining bricks come with detailed step-by-step drawing for installation, hence can be easily installed by a skilled or even semi-skilled mason under supervision of a civil / mechanical engineer by merely referring to the brick installation drawing corresponding to the bricks duly match marked.

CUSTOM DOOR LININGS : Duralox 92W pre-engineered lining bricks fit frames and doors or lip-over design doors and eliminate contamination from both door and steel frame. Each door and frame assembly is custom-designed to ensure longer trouble free service life.

Fixowel-F

Fixowel-F is a specially formulated epoxy based proprietary adhesive matrix developed by Jyoti Ceramic for fixing alumina ceramic mill lining bricks, wear resistant tiles etc. to a metal surface or ceramic surface. Fixowel adhesive cures within 24 hours at ambient temperature in natural atmosphere and the mill can be put into operation within 26 - 28 hours after installation of lining bricks. Duralox bricks with tongue and groove design, when fixed with Fixowel adhesive, ensure the highest stability and long lasting service life of mill lining.

Duralox® 92W

CERAMIC GRINDING MEDIA

Duralox ceramic grinding media and ball mill lining bricks are manufactured from the same fine grained composite and have proven to be ideal partners for high performance, since they retain their shape better and last longer than flint / river pebbles, natural stones, porcelain, steatite, etc.

Types of Duralox Grinding Media

Duralox 92W Ceramic Spherical Isostatically Pressed Grinding Media

Duralox 92W Ceramic Cylindrical Grinding Media

ADVANTAGES OF DURALOX® 92W CERAMIC GRINDING MEDIA

  • Higher density hardness and sphericity - As compared to flint river pebbles, natural stones and Steatie. Due to their higher density, hardness, toughness and higher degree of sphericity, Duralox ceramic grinding media save over 35% milling time.
  • Easy to use - Duralox grinding media are fully vitrified, non-porous and smooth as compared to other materials.
  • Longer milling life - As Duralox grinding media has dense, homogeneous internal microstructure, it offers superior wear resistance as compared to other conventional media.
  • Wide range of sizes - Duralox spherical isostatically pressed grinding media are available in 6 assorted sizes from Ø 20mm to Ø60mm to fulfill most demanding applications for dispersion and particle size reduction. Duralox cylinders with radius corners are available in 8 assorted sizes from Ø 6mm to Ø 30 x 30mm length
  • Uniform quality - Duralox grinding media are manufactured in the most modern plant under stringent quality control checks at various stages to ensure that the final product is consistently of highest quality level.

Duralox® 92W Ceramic Spherical & Cylindrical Grinding Media for various types of mills.

Ball mills are the most commonly used mills to accomplish particle size reduction. A revolving vessel, the ‘drum’, lined with ceramic bricks contains grinding media and the raw material to be ground.

Ball mills are classified into :

Batch type & Continuous type : Batch type ball mills are versatile and most widely used. Particle size reduction takes place by impact on the material with the tumbling grinding media and by abrasion between the media and the mill wall.

Selection of Grinding Media :

For a fresh charge, it is the most general practice to use three different ball sizes: 25% of large size, 50% of medium size & 25% small size. There might be cases where using 2 to 4 different size of grinding balls may be necessary. This will require a change in the proportions of each size used. For topping of the mill, we suggest a selection of the largest dia balls.

Recommended charge of material to be ground and grinding media.

Charge of material to be ground : There are no hard and fast rules about charging of mills; some general rules are adopted from experiences of operators which helps in achieving optimum milling efficiency at economical cost. In most cases, the quality of material to be ground should be 25-30% of mill’s useful volume. Non-obersvance of these limits can lead to high wear rate of grinding media and the mill lining or to a considerably longer grinding time

Recommended quality of Grinding Media :

To obtain the optimum grinding efficiency, we recommend :

1) For batch type mill : Grinding media should fill 55% of the mill’s useful volume.

2) For continuous type mill : Grinding media should fill 35% of mill’s useful volume.

To Calculate media charge for cylindrical mill, the formulae are given as below :

1. For batch type ball mill :

M = 0.000929 x D2 x L

Where
M = Weight of the grinding media charge in Kgs.
D = Mill internal dia in cms after lining.

L = Internal length of the mill in cms after lining.

Example : To calculate grinding media charge for a Duralox brick lined batch type mill size : Dia. 6' x 6' Long (Dia. 180 cms x 180 cms L) (Mill opening are not considered).

Thickness of tapered bricks = 5.0 cms.
Thickness of straight bricks = 5.0 cms.
Therefore
D = 180 - 10 = 170 cms
L = 180 - 10 = 170 cms.

M = 0.000929 x (170)2 x 170.0

Grinding media quantity = 4564 kgs.

2. For continuous type ball mill :
M = 0.000503 x D2 x L

Recommended suitable Duralox® mill lining thickness, media quantity, media sizes and mill rotating speed for cylindrical batch type ball mills of the same dia. x same length

Mill I. D. Lining thickness (mm) Usable volume of Mill (ltr) Media quantity @ 55% vol (kgs) Media size and quantity Speed in (rpm)
mm inch
300 12 25 12.30 14 100% Ø 20 mm 46-47
450 18 25 50.31 60 100% Ø 20 mm 37-38
600 24 25 130.70 155 100% Ø 25 mm 32 - 33
750 30 25 269.50 320 50% Ø 20mm + 50% Ø 25 mm 30 - 31
900 36 40 433.20 512 25% Ø 25 mm + 50% Ø 30 mm & 25% Ø 40 mm 27 - 28
1050 42 40 717.10 848 25% Ø 25 mm + 50% Ø 30 mm & 25% Ø 40 mm 25 - 26
1200 48 40 1103.90 1305 25% Ø 25 mm + 50% Ø 30 mm & 25% Ø 40 mm 23 - 24
1350 54 50 1534.70 1815 25% Ø 30 mm + 50% Ø 40 mm & 25% Ø 50 mm 21 - 22
1500 60 50 2156 2550 25% Ø 30 mm + 50% Ø 40 mm & 25% Ø 50 mm 20 - 21
1800 72 50 3860.40 4564 25% Ø 30 mm + 50% Ø 40 mm & 25% Ø 50 mm 18 - 19
2100 84 65 6007.40 7103 25% Ø 40 mm + 50% Ø 50 mm & 25% Ø 60 mm 16 - 17
2400 96 65 9191 10868 25% Ø 40 mm + 50% Ø 50 mm & 25% Ø 60 mm 15 - 16
2700 108 65 13337 15772 25% Ø 40 mm + 50% Ø 50 mm & 25% Ø 60 mm 14 - 15
3000 120 75 18189 21508 25% Ø 40 mm + 50% Ø 50 mm & 25% Ø 60 mm 13 - 14
3600 144 75 32265 38154 25% Ø 40 mm + 50% Ø 50 mm & 25% Ø 60 mm 12 - 13

* Media charge @ 50% to 55%, material charge @ 30% to 45%, liquid to adjust the solid content @ 50% to 70% of the material charge

Recommended mill rotation speed :

Mill rotating speed is an important parameter for optimizing grinding efficiency :
  • Using proper speed has a cascading effect where the charge and grinding balls roll over one another, thus developing maximum milling action with minimum wear of grinding media and lining.
  • If the ball mill rotates at an excessive speed, there will be centrifugal effect and no particle size reduction will take place.
  • If the speed is too slow it results in purring effect where the charge is lifted to small angle and balls tend to slide back on the lining hence the grinding action is poor.

Calculations for mill motor power & mill speed

Considering the weight of mill lining and grinding media, work out motor power required, in consultation with the mill manufacturer

To calculate the motor power required for a cylindrical type ball mill, the following formula can be applied

W = 0.04116 x D3 x L x n x (0.6d + 0.4d1)

Where:

W = Required motor power in HP

D = Internal dia. of the mill in mtrs.

L = Internal Length of the mill in mtrs.

d = Specific gravity of grinding media

d1 = Specific gravity of substance

n = Speed of ball mill in rpm

Example : Let the internal dia. of the mill be 1.8 mtrs. and internal length be 1.8 mtrs. If Duralox grinding media is used density d = 3.7 gms/cc. If milling substance is alumina in slurry form with around 70% solids.

then d1 = 1.8
d = 3.7 and d1 = 1.8 then

W = 0.04116 x (1.8)3 x 1.8 x 1.9 x 19 x (0.6 x 3.7 + 0.4 x 1.8) = 24.13 HP

To calculate the speed of the mill use the following formula :


where :
Nc = Critical speed

D = Internal dia. in ft.

Actual speed of the mill should be approximately 62% of the NC for wet milling and 75% of Nc for dry milling.

Table indicating the optimum mill speed and motor power of ball mills

Inside dia (mm) Inside length (mm) Dry grinding with Duralox Media
Speed (RPM) Motor Power (HP) Speed (RPM) Motor Power (HP)
300 300 54 1/2 38 1/2
450 450 44 1/2 31 1/2
600 600 38 1 27 1
750 750 34 11/2 24 11/2
900 900 31 3 22 3
1050 1050 29 5 20 5.0
1200 1200 27 71/2 19 7.5
1350 1350 25 15 18 12.5
1500 1500 24 15 17 15
1800 1800 22 30 16 25
2100 2100 20 40 15 40
2400 2400 19 75 14 50
2700 2700 18 100 13 100
3000 3000 17 150 12 125

Jar mills : Particle size reduction takes place by impact over the material with the tumbling grinding media and by abrasion between the media and the mill wall. It works on the same principle as batch type ball mills.

Recommended grinding media :

Balls of Ø 12.5mm to 20mm.

Vibro mills : Find their cheap advantage in fine grinding by producing particle size less than 1 micron and finer. The high impact of conventional ball mills is not needed in vibro mils. Instead a large number of low energy impacts are necessary using small grinding media with high vibration or rotation rate.

Recommended grinding media : Cylinders of Ø 6.0 mm to Ø 20.0 mm. Recommended media charge : 60 - 70% of mill’s useful vol.

Calculation of media load

Example :

Vibro mill net volume is 350 Ltr charging with Ø 12.5 mm cylinders.
60% mill’s vol = 210 Ltr x 2.1 kg/Ltr (Bulk density of Duralox media) That is 441 kg of Duralox grinding media required for 350 Ltr capacity Vibro mill.

Wear Rate Test procedure

Jar Mill 20 Ltr capacity rubber lined % Cum wear loss / hr after 120 hrs of wear : 0.01624

Grinding media is weighed on Electronic Balance of 10mg resolution, loaded into the jar mill along with silica sand and water, then milled for 24 hrs. After milling grinding media is unloaded, washed, dried thoroughly and weighed again. Weight loss percentage per hour is calculated. This process is repeated every 24 hours for a total of 120 hours. Graph of wear rate versus time is drawn. It is inferred from the graph that the wear rate reduces with time up to around 0.01624% per hour for Duralox grinding media and then remains almost constant.

Speed 55 rpm
Grinding media charge Duralox 92W grinding media Ø 50mm
Material charge 5 kg silica sand of 0.3 mm size
Quantity : 2784.36 gms
Water 5 Ltr

Mode of Packaging :

  • Ceramic macro grinding media are packed in strong double lined HDPE plastic bags.
  • Each bag contains grinding media of net weight 25 kg / 50 kg.
  • For exports, these HDPE plastic bags are repacked in strong, sea-worthy wooden pallet type crates.

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Duralox® Ceramic Grinding Media & Ball Mill Lining
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