In a laboratory, most materials required for sampling are, in practice, nonhomogeneous mixtures. The best method of obtaining a small representative sample of the nonuniform whole is to take a quantity of the material large enough to be compositionally representative and reduce it to a fine homogeneous powder. For this purpose, a laboratory mill/ grinder is usually used.
Top 5 Questions You Should Ask When Buying a Mill or Grinder
1. Will the mill/grinder be used for wet or dry milling?
2. For dry milling, ask how finely the material needs to be ground and what are the properties of the material? Rotor beater, disc, and mortar mills, for example, are best for mid-range grinding (final fineness of ~0.01-0.1 mm).
3. For wet milling, ask what capacity of grinder you will need. Bead mills are usually best for small capacity applications while rotor-stator homogenizers should be considered for larger scale applications. For very large scale applications, industrial-scale mills are probably the best fit.
4. How important is preventing crosscontamination? Bead mills are likely a good choice if you don’t want any risk of contamination.
5. Based on the materials you will be milling, how long does the miller or grinder typically last? How much do replacement parts cost and how easy are they to get? What level of support/warranties does the company offer?
Recent Trends in Milling & Grinding:
• Milling and grinding are ancient techniques that are working their way into high-tech markets. Demand for particle size reduction systems has grown significantly from “alternative” industries. In particular, demand from the energy sector has been substantial, especially for processing biomass materials such as wood, refuse, and even garbage. Solar energy R&D is another emerging venue.
• The breadth of life science applications has given rise to fierce competition between homogenization and milling/grinding. Both have utility in this area, but the tug of war between competing methods goes on.
• For some pharmaceuticals, the higher end of the nano-size domain might be just what the doctor ordered. Ball milling is being investigated extensively for drug particle size reduction; the manufacturing processes for five approved drugs already use milling.
Recently Released Mills & Grinders
• Provide optimized air throughput and cooling of sample and grinding tools
• Allow for improved material discharge resulting in less cleaning
• Give users complete recovery of sample material
• RETSCH line of lab mills includes various models which can be equipped with a cyclone, such as the TWISTER and ZM 200
• Batch mill with single-use milling vessels enables serial testing to be carried out under reproducible conditions
• Single-use milling vessels save on cleaning, time and energy; they also prevent cross-contamination
• 40 ml capacity milling vessels and hood are made from transparent material, allowing the milling process to be observed at any time
• Ensures uniform batch-to-batch mixing characteristics
• Designed to operate at temperatures up to 260°C, with an accuracy of ± 1°C
• Provides high torque output from a 2.5 HP sensor-less vector drive with built-in torque overload protection
• Utilizes improved transfer rolls coated with Acrotherm TK400 (RC 70), an extremely durable coating for high wear resistance
C.W. Brabender Instruments
6970 EFM Enclosed Freezer/Mill
• Features a totally enclosed liquid nitrogen (LN) auto-fill system with external loading of sample vials
• Includes a pre-cooling chamber, allowing additional samples to be cooled while the grinding chamber is in operation
• Controlled by a color touch screen interface that can store up to 10 programs for rapid process replication and consistency
Mill & Grinder Manufacturers
|C.W. Brabender Instruments||www.cwbrabender.com|
|Hitachi High Technologies||www.hitachi-hta.com|
|The Fitzpatrick Co||www.fitzmill.com|
|The Jet Pulverizer Co||www.jetpul.com|