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Marsh
Trees House Marsh Parade Newcastle-under-Lyme Staffordshire ST5 1BT United Kingdom Tel: +44 (0) 1782 622666 Fax: +44 (0) 1782 622655 |
Grinding Media
Many minerals used in manufacturing processes need to be finely ground before they can be utilised in the preparation of the final product.
Whitfield and Son Limited offer a wide range of grinding media to enable cost effective reduction of the particle size of the materials.
A high alumina 90%+ Al2O3 (Alugrind) is isostatically pressed and sintered at high temperature to give a finished product. Alugrind 90 has a density in excess of 3.57gm/cm³ and is completely gas-tight. Isostatic pressing ensures that the density and hardness of the product is the same from the outside surface to the centre of the media and this ensures extremely low and uniform wear rates. High density alumina media is used to grind material where contamination must be kept to an absolute minimum, but because of the very high efficiency of Alugrind 90+ it is finding increasing use in the production of numerous materials from ceramic raw materials to colours, glazes and technical ceramics.
A range of 90% Al2O3 Mini Media is also available for special applications.
A 65% Al2O3 isostatically pressed and sintered grade is also available for less demanding requirements. This has a density in excess of 2.9g/cm³ and again is completely gas-tight. It is suitable to use in areas previously covered by steatite or porcelain media.
Silica Pebbles are the traditional grinding media for all general purpose grinding of bulk materials such as silica and feldspar. Our supplies are selected from the natural pebble deposits in Southern England and Northern France.
Glass Beads of 3 types are available:
GJ-I - General type for normal grinding situations.
GJ-II - Strengthening type which exhibits good hardness and wear resistance.
GJ-III - Wear resisting type with higher density, superior wear resistance even in high intensity grinding.
YTZ ceramic media features high density and super hardness which enables the user to achieve superior grinding efficiency. The high wear resistance YTZ ceramic media effectively eliminates product contamination and other problems associated with the use of lower quality grinding media, which may be prone to chemical attack or short mill life.
We have available Zirconium Silicate Beads made by a fusion process giving a fine crystalline structure. This material can be used in the grinding of coatings, inks, dye stuffs, pesticides, cosmetics, titanium dioxide, magnetic materials and numerous other minerals.
| Alumina 65 | Alumina 92 | |
| Chemical Analysis | ||
| Al2O3 Content | 65% min | 91.5% min |
| Physical Properties | ||
| Shape & Colour | Spherical, Light yellow or white | |
| Hardness (Moh's) | > 7.50 | > 9.00 |
| Specific Density | > 3.00 g/cm³ | > 3.60 g/cm³ |
| Water Absorption | < 0.02 % | |
| Wear Rate | < 1.50 % | < 0.20 % |
| Size Range Available : | ||
| Alumina
grinding balls are available in sizes from 20mms to 70mms. 75%, 85% and 95% alumina content are also available. Alumina linings for ball mills are available in 50mms and 60mms thickness. Alumina mini media is available in sizes from 3mm to 20mms. |
||
| GJ - I General Type |
GJ - II Strengthening Type |
GJ - III Wear-Resisting Type |
|
| Size | 0.2-4.0 mm | 0.6-4.0 mm | 0.6-4.0mm |
| Chemical Analysis | |||
| SiO2 | 72.10 % | 73.95 % | 59.00 % |
| Al2O3 | 1.76 % | 5.42 % | 2.30 % |
| CaO | 6.80 % | 0.91 % | 7.50 % |
| MgO | 3.80 % | -- | 3.00 % |
| Na2O | 14.80 % | 7.30 % | 9.50 % |
| BaO | -- | 2.90 % | -- |
| B2O3 | -- | 9.10% | -- |
| ZrO2 | -- | -- | 14.50% |
| TiO2 | -- | -- | 4.20% |
| Physical Properties | |||
| Density | 2.45/g/cm³ | 2.50 g/cm³ | 2.80 g/cm³ |
| Hardness | >635 kg mm² | >680 kg mm² | >720 kg mm² |
| Mohs | 6 | 6 | 6 |
| Chemical Analysis | Typical Values |
| Composition | ZrO2 + HfO2: 95.00 ± 0.50 wt% Y2O3 : 5.00 + 0.20/-0.60 wt% |
| Specific Density | ≥5.95 g/cm³ |
| Bulk Density | 3.7 kg/L (dia.7mm) |
| Hardness (HV 1) | ≥10.00 Gpa |
| Modulus of Elasticity | 210 Gpa |
| Thermal Conductivity | 3W/m K |
| Crushing Load | Depends upon Size |
| Bending Strength | 1200 MPa |
| Size Range | 0.1, 0.2, 0.3, 0.5, 0.65, 0.8, 1.0, 1.5, 2.0, 3.0, 5.0, 10, 15, 20, 25mm |
| Cylindrical Media is available in the following standard sizes: nom 9.5mm (3/8"), nom 12.25mm (½") |
| Chemical Analysis | Typical Values |
| Composition | 68.5% ZrO2 |
| Specific Gravity | 3.85 g/cm³ |
| Density | 3.86 kg/L (dia.7mm) |
| Mohs Hardness | 7. 2 |
| Wear (Vibration grinding of corundum for 5 hours) | 0.062 % |
| Compressive Strength | 710 N |
| Size Range | 0.2-0.6mm, 0.6-1.00mm, 0.8-1.25mm, 1.0-1.6mm, 1.6-2.5mm |
| Special sizes are available. |
Media loading affects the grinding time and efficiency.
At 50% media volume fill the grinding time is the shortest coupled with maximum
efficiency.
Normal media loading is 50-55% of mill volume.
Generally:
25 % Small balls
50 % Medium balls
25 % Large balls
Please contact our technical sales for specific recommendations.