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Grinding and Pulverizing
What are the SPEX SamplePrep laboratory mills designed for?
SPEX SamplePrep mills are intended for the analytical laboratory. They are not for batch or production milling, but for rapid, efficient grinding of analytical samples ranging in amounts from less than one gram up to approximately 100 grams. The hallmark SPEX SamplePrep Freezer/Mills, Mixer/Mills and Shatterbox all have separate grinding containers for individual samples, so after use the container is cleaned and not the mill. SPEX SamplePrep mills were designed for spectroscopists who were concerned not only about reducing samples to uniform homogeneous powders, but also about what was added to the samples during processing.
How do I use my choice of grinding container to minimize sample contamination?
Processing a sample always contaminates it. Successful analysis depends on recognizing the sources of contamination and controlling them. When the contaminants are known and can be quantified, analytical results can be refined accordingly. As the grinding container is the major source of contamination, its selection is critical. In general, one’s objective should be to minimize contamination levels while avoiding elements which will interfere with analysis. An example is the grinding of steel slags in a tungsten carbide container: tungsten carbide grinds rapidly, and the expected low-level contaminants of tungsten, carbon, and cobalt are not generally looked for in these slags. SPEX SamplePrep’s selection of grinding container materials gives you maximum flexibility in choosing the best approach for your samples and analytical aims. Major, minor, and trace elements predictably found in SPEX SamplePrep grinding containers are listed in the SPEX SamplePrep Grinding Container Material Selection Chart. However, strictly speaking, almost no two grinding containers will have exactly the same elemental profile. There are many different steels, carbides, and ceramics, each with specific compositions. Often the formulas are proprietary, so that a type of tungsten carbide engineered to have specific properties will have a different makeup from two different manufacturers. In addition, there are inevitable variations from batch to batch of the same material, both in the exact proportions of the major elements and in trace element composition. Because of these variations in grinding container composition, we strongly recommend determining the exact elemental profile of your individual grinding containers, preferably with your own analytical equipment and techniques. The simplest approach is to grind samples of known composition and see what is added by grinding. Lacking known samples, one may grind portions of a single sample for increasing lengths of time, and check to see which elements increase in proportion to grinding time. Once the contributed impurities and their proportions are known for a grinding container, the resulting profile can be fitted to the analytical results, regardless of the actual contamination level. (While this level is important, it clearly will vary with the composition and condition of the grinding container, the size, hardness, and toughness of the sample, and grinding time).
How can I prevent my sample from caking during grinding?
When samples agglomerate or “cake” during grinding, further particle size reduction is clearly inhibited. Caking can result from moisture, heat, static charge accumulation, the fusing of particles under pressure, and other causes. Many of the techniques which make sample preparation an “art” are devoted to getting around caking, and we can only hint at the possibilities.
Slurry grinding is an obvious approach; if particles remain in suspension during grinding, they are unlikely to cake. Water, alcohol, or other liquids are added to the sample before grinding, and removed afterwards. Although slurry grinding is a reasonably reliable way of grinding a sample to micron-sized particles, it is sloppy and time consuming, requires a leak proof grinding container, and adds extra steps to one’s sample preparation procedure.
Dry grinding is simpler and quicker, but requires much more careful matching of the technique to the sample. If the caking is due to moisture, as in many soils and cements, the sample can be dried before grinding. Other samples can be successfully ground with a variety of additives. Dry soaps/detergents are lubricants, and some also include an abrasive; graphite is an anti-static agent as well as a lubricant; there are many proprietary grinding aids as well, which may contain an abrasive, a lubricant and a binding agent. Other grinding aids include polyvinyl alcohol, phenyl acetate and aspirin.
Can the Mixer/Mill® be used for mechanical alloying?
Mechanical alloying, also referred to as reactive milling, is a process originally developed for the production of oxide dispersion strengthened superalloys. Today, mechanical alloying is often used as a solid-state powder processing technique that generates powders with unique microstructures. A high-energy ball mill can be used to accomplish this. Over the past few decades, the SPEX SamplePrep Mixer/Mill, widely known as the “SPEX Mill”, has become the industry standard for mechanical alloying applications. The high energy of the milling action, and the durability of the motor, allow running for extended periods.
The SPEX SamplePrep 8000M Mixer/Mill® and 8000D Dual Mixer/Mill® are equipped with a timer that is factory set for a 100-minute time range. However, mechanical alloying requires significantly longer grinding times. For these applications, SPEX SamplePrep offers an optional chip (39450 Chip for Extended Running Time) to extend the timer range to 1,000 or 10,000 minutes. This chip is available as either a factory-installed or user-installed option. Due to the extreme wear that can occur on the Mixer/Mill from extended running times, installation of this chip will change the warranty terms (consult SPEX SamplePrep sales or service). Additionally, in order to prevent the mill from breaking down prematurely, a routine schedule of preventative maintenance is strongly suggested.
What is the typical cryogenic grinding technique?
Cryogenic grinding presents unique challenges for designers of laboratory mills, as the low temperatures required are very hard on mechanical equipment. The 6770 Freezer/Mill® and 6870 Large Freezer/Mill® impel a steel impactor magnetically while the sample vial is immersed in liquid nitrogen. Once chilled, samples can be pulverized quickly; grinding times rarely exceed a few minutes with either mill.
A typical milling program involves pre-cooling the sample. Chilling times vary with the mill and the insulating ability of the sample but can range from 10 minutes to 30 minutes or more. This is followed by one or more grinding cycles, each of which consists of a grinding period followed by a pause for re-cooling. An example is 15 minutes of precooling followed by three 2-minute grinds with two-minute rests in between each grinding period.
The optimum volume, weight, grinding time, and impact frequency for any sample ground in a SPEX SamplePrep Freezer/Mill are determined by experimentation, the experience of the operator, and the requirements of the analyst. As a rule of thumb, the smaller the sample and the longer it is ground, the finer the particle size will be. In cryogenic grinding, temperature also affects the outcome: the colder a sample, the more finely it can be ground. We strongly suggest submitting samples for test grinding if there is any question about the suitability of our mills and techniques for your application.
What type of controls do the Freezer/Mills® have?
The 6770 Freezer/Mill® and the 6870 Large Freezer/Mill® feature LCD touch-screen displays used for programming and manual control. A typical milling program involves pre-cooling the sample. This is followed by one or more grinding cycles, each of which consists of a grinding period followed by a pause for re-cooling. An example is 15 minutes of precooling followed by three 2-minute grinds with two-minute rests in between each grinding period. With these new Freezer/Mill models such a cycle can be programmed and it is possible to store up to ten grinding programs.
The LCD touch-screen display is incorporated in a detachable control module located on the lid of the mill. The control module can be detached for remote use via a cable. This is ideal for operating the mill in a glove box or under sterile conditions.
What safety features are the Freezer/Mills® equipped with?
Both the 6770 Freezer/Mill® and the 6870 Large Freezer/Mill® include latch-down lids with a lid sensor that prevents the mill from being operated when the lid is open. A liquid nitrogen sensor detects the level of liquid nitrogen in the mill and will not allow operation if the liquid nitrogen level is too low. The 6870 Large Freezer/Mill® has an auto-fill option that eliminates direct handling of liquid nitrogen. Both Freezer/Mill models are CE Approved.
How do the Freezer/Mills® aid in the screening of asbestos-containing materials (ACMs)?
Typically the floor tiles, ceiling tiles, and pipe insulation being checked for harmful asbestiform minerals are composite materials which are both flexible and tough. The challenge is first to free the mineral fibers from their matrix and then to determine whether they are among the species most damaging to human health. Freezer/ Mills are useful not only to break up the matrix and free included fibers for polarized-light microscopy, but also to grind those fibers finer for X-ray diffraction analysis.
A wide range of Application Notes which discuss the various Freezer/Mill® applications in more detail are available.
Who uses the Freezer/Mills® and what are their applications?
SPEX SamplePrep Freezer/Mills are incredibly versatile instruments. They are used by polymer chemists, forensic experts, environmental biologists, geneticists, botanists, doctors and dentists, geologists and mineralogists, and many others. Applications include DNA and RNA extraction, polymer structure studies, trace element monitoring, food analysis, mineral diffraction research, implant surgery, drug testing, textile identification and more.
A wide range of Application Notes which discuss the various Freezer/Mill® applications in more detail are available.
What are the principles behind the grinding action used in the Micro Hammer-Cutter Mill?
The innovative design of the 5200 Micro Hammer-Cutter Mill utilizes high-speed revolving hammers and a serrated grinding chamber lining to combine the shearing properties of a knife mill with the crushing action of a hammer mill. Operation of the 5200 Mill is quite straightforward. Up to 100 mL of the sample material is placed in the hopper. A slide at the bottom of the hopper is manipulated to feed small amounts of the sample into the grinding chamber. When the material has been sufficiently pulverized, it drops through a perforated-steel screen at the bottom of the grinding chamber into a tightly fitted collecting tube.
What type of controls and safety features is the Micro hammer-Cutter Mill equipped with?
Particle size and rapidity of grinding in the 5200 Micro Hammer-Cutter Mill are determined by interchangeable screens and a variable-speed motor control. A circuit breaker prevents overloading, and a safety switch turns off the motor when the grinding chamber door is opened. All grinding chamber components are made from 410 stainless steel. The hammers and liner can be easily removed for cleaning.
How do I choose a Mixer/Mill®?
Which SPEX SamplePrep Mixer/Mill is best for your application can best be determined through three criteria: 1. The weight/volume of the sample to be ground. 2. The number of samples per day. 3. The preferred grinding container material.
5100 Mixer/Mill – The smallest of the SPEX SamplePrep Mixer/Mills has the capacity for running three ½ in. (12.7 mm) diameter x 1 in. (25.4 mm) long or two ¾ in. (19 mm) diameter x 2 in. (50.8 mm) long grinding vials. The weight of typical samples for this mill is around 0.5 g for the smaller vials and 1 g for the larger ones.
8000M Mixer/Mill® and 8000D Dual Mixer/Mill – The larger SPEX SamplePrep Mixer/Mills typically grind samples in the 10 g range. Both mills use the same vials but 8000D has a dual clamp and thus twice the output of the single clamp 8000M. The smaller capacity vials traditionally used in the 5100 can also be used in the 8000M and 8000D with a special adapter.
What is the difference between the 8000M Mixer/Mill® and the 8000D Mixer/Mill®?
The SPEX SamplePrep 8000 Series Mixer/Mills are efficient compact laboratory mills capable of pulverizing one or two samples in the 10-gram range. There are two versions: the classic 8000M Mixer/Mill with one clamp, and the 8000D Dual Mixer/Mill with two clamps.
The single clamp 8000M (previously the 8000) is known simply as “the SPEX Mill” to thousands of users and has been in service for over forty years. The clamp mechanism has changed little since the earliest versions, simply because it has proven extremely durable. Many of the earliest 8000 Mixer/Mills are still in service. Now the wind-up timer has been replaced by an electronic 100-minute timer (extended timer available 39450 Chip for Extended Running Time) and the mill’s safety features have been improved.
The dual-clamp 8000D Mixer/Mill combines two clamps on one shaft with an electronic 100-minute timer (extended timer available). As the two clamps move in balance, vibration is reduced and component life extended. A fan keeps the clamps and motor cool during operation.
What types of grinding vials are available for the 8000M Mixer/Mill® and 8000D Dual Mixer/Mill®?
8000 Series grinding vials are 2 1⁄4 in. (5.7 cm) wide and up to 3 in. (7.1 cm) long. They have an internal volume of 50-60 mL with a grinding capacity of about 10 mL and a blending capacity of 25 mL. They are available in hardened and stainless steel, tungsten carbide, alumina ceramic, zirconia ceramic, silicon nitride, agate, and methacrylate.
We recommend that vials for the 8000D Dual Mixer/Mill be purchased and used in pairs to maintain the balanced motion of the clamps. If only one sample needs to be ground, the second similar vial should be clamped in place without the sample or grinding ball.
What are the principles behind the grinding action in the 8000M Mixer/Mill® and 8000D Dual Mixer/Mill®?
The SPEX SamplePrep 8000 Series Mixer/Mills are functionally described as shaker mills or high-energy ball mills. They shake one or two containers back and forth several thousand times a minute. In each clamp, the vial, which contains a sample and one or more balls, is shaken in a complex motion which combines back-and-forth swings with short lateral movements, each end of the vials describing a “figure-eight”. The length of that swing is the same as the internal length of the vial, about two inches (5.08 cm). With each swing the balls impact against one end of the vial, simultaneously milling the sample to a powder and blending it. Due to the amplitude and velocity of the clamp’s swing, each ball develops fairly high G-forces, enough to pulverize the toughest rocks, slags, and ceramics.
How to I choose a laboratory mill?
If your samples can be pulverized by impact at room temperature, you have a choice of several proven SPEX SamplePrep laboratory mills. The 8530 Enclosed Shatterbox® and 8500 Shatterbox® are ring-and-puck mills that are ideal for rapid grinding of samples up to approximately 100 grams, in 5 minutes or less. The 8000M Mixer/Mill® and 8000D Dual Mixer/Mill® are high-energy ball mills that not only pulverize samples in the 10 gram range but are suitable for blending powders and making emulsions up to approximately 50 mL. The 5100 Mixer/Mill® is a smaller high-energy ball mill, with about 10% the sample capacity of the 8000-series Mixer/Mills. All these mills have multiple-sample capacity with smaller samples, and a wide choice of grinding container sizes and materials, for maximum on-the-job flexibility over a wide range
of applications. Soft, brittle materials and flexible samples that can be ground by shearing as well as impact may be suitable for the 5200 Micro Hammer-Cutter Mill, which uses revolving hammers in a chamber with a serrated lining. Product particle size is controlled by perforated screens in the bottom of the grinding chamber. This is the only “flow-through” mill sold by SPEX SamplePrep, and has proven useful for a comparatively narrow range of samples. The 6770 Freezer/Mill® and 6870 Freezer/Mill® are unique cryogenic mills that can grind almost any “ungrindable” sample, including all plant and animal tissue, most polymers, and countless other samples that are resistant to room-temperature milling. Freezer/Mills require liquid nitrogen for chilling the sample, and maintaining cryogenic temperatures in the vial during grinding. Forty years after its introduction the Freezer/Mill remains the most widely used and most effective cryogenic mill in the world. Finally, the 2000 Geno/Grinder® is a high-throughput tissue homogenizer with an adjustable clamp that accommodates a variety of formats ranging from deep-well titer plates to centrifuge tubes. It is specifically designed for rapid cell disruption, lysis, and tissue homogenization while preserving temperature sensitive samples. To discuss any SPEX SamplePrep laboratory mills and their suitability for your applications, feel free to contact our product specialists. We also offer test-grinding of your samples in our applications lab, or we can loan you a mill for short-term trials in your own lab. The more you know about SPEX SamplePrep laboratory mills, the more confident you can be that they will do the job you need to get done.
How do I choose a grinding container?
Your selection of appropriate grinding and mixing containers is as important as your choice of a mill. The proper grinding vial or dish will greatly enhance analytical accuracy. The grinding container is generally harder than the material to be ground and should be of a substance whose presence in the sample will not interfere with analysis. SPEX SamplePrep’s containers have been selected with care to offer optimum capability in the lab. The following is a brief description of the pros and cons of each grinding container material. Please keep in mind that not all materials are available for each of SPEX SamplePrep’s laboratory mills. Methacrylate and polystyrene vials and balls are ideal for pulverizing soft, brittle materials and for mixing and storing powders. With these vials only traces of organic impurities are added to your sample. Hardened steel is durable and tough, suitable for general-purpose grinding; it’s the workhorse of the lab. When hard substances are ground in steel containers, some Fe and Cr contamination can be expected. Stainless steel is less subject to chemical attack, but contributes Ni as well. Cr-free steel rusts easily but can be used to grind samples for RoHS/WEEE testing. Halide-releasing compounds corrode steel and should be ground in tungsten carbide, alumina, agate, zirconia, or silicon nitride containers. Tungsten carbide vials and dishes are the most effective and versatile of all. Because tungsten carbide is substantially harder and heavier than steel, grinding is faster and contamination is minimal. Other than tungsten, cobalt (a binder) is the major contaminant. If cared for, tungsten carbide containers will last indefinitely. They’re recommended as a long-term “best buy” for grinding almost anything. Alumina ceramic is ideal for extremely hard samples or in cases where steel and tungsten carbide contaminants are objectionable. All SPEX SamplePrep alumina components are 99.5% pure aluminum oxide, with some silicon, calcium, and magnesium present. It is lightweight and brittle but very abrasion-resistant. Necessary for an important minority of samples, alumina ceramic vials are a helpful addition to any lab’s grinding armory. Agate is harder than steel, and chemically inert to almost anything except HF. It’s also brittle and must be handled with care. Agate vials are for the grinding and mixing of samples when organic and metallic contamination are equally undesirable. Agate is 99.9% silica and is extremely wear-resistant. Silicon nitride is a tough space-age material with remarkable wear characteristics, and hardness superior to agate and zirconia. If it is important to have a container whose only major contaminant is silicon, consider SPEX SamplePrep silicon nitride. It is extremely durable compared to agate, and while it contains some yttria and alumina, overall contamination levels will be very, very low. Zirconia is a ceramic which in many ways approaches the ideal grinding medium. Since it is both hard and tough it wears very slowly, adding little contamination. It is about one and one-half times as dense as alumina, grinding almost as fast as steel. And because it is mostly zirconium oxide with low percentages of magnesium oxide and hafnium oxide, the contamination SPEX SamplePrep zirconia ceramic does contribute is often not important to the analyst.
What is the procedure for using propylene glycol as a grinding aid?
Howard Kanare of Construction Technology Laboratories, Inc. has publicized the use of propylene glycol (one drop for up to ten grams of sample, roughly 0.3 wt.%) for laboratory fine grinding of Portland cement and many minerals. In a swing mill such as the SPEX SamplePrep Shatterbox, oven-dried samples can be ground quickly to less than ten microns without agglomeration or sticking to the mill walls. Propylene glycol must be used safely, after consulting the material safety data sheet; it is available as a PrepAid product (see pages 68 and 76).
What are the benefits of cryogenic grinding?
While cryogenic grinding has long been a vital sample preparation tool for the analytical chemist, it rarely receives publicity. The recent identification of the remains of Czar Nicholas II of Russia not only solved a mystery nearly eighty years old but also emphasized the importance of cryogenic techniques in both forensic and archaeological research. DNA was successfully extracted from the Romanov bone fragments after they had been ground in a SPEX SamplePrep Freezer/Mill.
Many analytical samples which are too flexible or sensitive to be impact-ground at room temperature can be embrittled by chilling, and then pulverized. These include polymers, rubber, textiles, cereal grains, hair, fingernails, skin, bone, and muscle tissue. There are also many samples which degrade in various ways during normal grinding, but whose critical properties are preserved by chilling. Coal, for example, can be cryogenically ground to retain its more volatile components, and clay minerals may be pulverized for XRD study without distorting their crystal structure. Bone, fingernails, and other biological materials can be cryogenically ground in preparation for nucleic acid extraction without damaging DNA and even RNA through heating.
What is the recommended procedure for cleaning Mixer/Mill® Grinding Vials and Shatterbox® Grinding Containers?
Grinding vials and containers should be cleaned between sample runs to avoid cross-contamination, and the procedure can be as simple or as complex as your analytical objectives warrant. In some applications a simple wipe down with ethanol may suffice; another practical approach is to brush out a container, then briefly grind an expendable portion of the next sample and discard it.
For more thorough cleaning one may grind one or more batches of pure quartz sand, and then wash the container thoroughly. In extreme cases, such as the plating of container walls with a malleable metal, chemical cleaning or multiple grinds with quartz may be necessary.
An effective single-step grinding procedure for most grinding containers is to grind pure quartz sand together with hot water and detergent, then rinse and dry the container. Drying is speeded by the use of a blow-dryer or similar appliance. A safety advantage of this cleaning method is that it controls respirable airborne dust.
A cleaning procedure is easily evaluated by grinding and analyzing a known sample, or even by checking the impurities appearing in successive batches of ground quartz sand. It should be noted that grinding containers become more difficult to clean with age because of progressive pitting and scratching of the grinding surfaces.
Hardened steel and even stainless steel containers can rust. While iron oxide coatings can be removed by warm dilute oxalic acid solution or abrasive cleaning, we recommend that steel containers be thoroughly dried after cleaning and, if stored, kept in a plastic bag with a desiccating agent.
What is the recommended procedure for cleaning Freezer/Mill® Grinding Vials?
All of the Freezer/Mill® Grinding vials may be superficially cleaned quickly and easily by placing them under running hot water. If the vial is cold a coating of ice will form on the steel parts, but will melt quickly as the water runs.
All of the basic grinding vials have polycarbonate center cylinders. The Poly-Vial has polycarbonate center cylinders and end caps. While this polymer is very tough at low temperatures, it is sensitive to alcohol and other organic solvents, and should be cleaned only with soap and water. A mild bleach solution will control organic contamination. Polycarbonate can be autoclaved, but this will weaken it.
Before re-using polycarbonate cylinders, always inspect them for cracks. They may last for dozens or hundreds of samples, but as soon as they begin to crack they should be discarded.
If sample adheres to the steel end plugs and impactor, they can be cleaned with water and soap or detergent, or even with organic solvents. If they must be disinfected or cleaned of any organic residue, they can be washed with bleach or chemical cleaners or autoclaved, but should always be dried immediately after use. The steel parts in the basic grinding vials are made out of a so-called “magnetic stainless steel”, which is corrosion-resistant but will rust if left in contact with water. Surgical-grade stainless steel, which is truly rustproof, is nonmagnetic and cannot be used for Freezer/Mill end-plugs and impactor.
The steel parts of the Cr-Free Grinding Vials can also be washed, autoclaved, etc., but chromium-free steel is not rust-resistant and must always be dried after use. Store these parts in a sealed bag with a desiccant.
Rust on steel Freezer/Mill parts can be removed by scrubbing them with steel wool or an abrasive cleanser. If rusting persists, store the parts in a sealed bag with a desiccant.
Is respiratory protection required during grinding?
The general objective of sample grinding is, of course, to convert an inhomogeneous solid to a fine, homogeneous powder. Inevitably, some of this powder is released into the environment, usually during the emptying or cleaning of the grinding container. We strongly recommend the wearing of an approved dust-mask during this procedure, and suggest the use of a laboratory fume hood. Even harmless rock and cement samples can become potentially harmful to the respiratory system when finely pulverized.
How are Mixer/Mills® used to prepare infrared mulls?
KBr pellets and Nujol mulls are quickly prepared with SPEX SamplePrep Mixer/Mills using small plastic (3111 2.5 mL Polystyrene Vial with Slip-On Cap), agate (3118 Agate Grinding Vial Set, 1.6 mL) and steel vials (3114 Stainless Steel Grinding Vial Set, 2.5 mL). The polystyrene spectrum appears as a constant background and can easily be subtracted. Steel and agate produce no IR background.
What types of samples can be cryogenically ground?
Nearly every naturally occurring material of biological origin can be cryogenically ground, usually to a fine particle size: hair, muscle tissue, bone, wood, plant stems and roots, seeds, cotton fiber, etc.
Polymers in general can be ground, but their physical form is important. Many flexible plastics which can routinely be milled in pellet form are difficult to grind as thin fibers and films, which remain flexible even at -200°C. For the same reason, polymers in general cannot be ground to as fine a particle size as biological samples. As the particles become smaller they become more flexible, and progressively more difficult to grind. Many silicone compounds remain elastic and hard-to-grind in any form.
The behavior of metals and metal alloys during cryogenic milling is highly variable. For example, impure copper as well as many copper alloys can be ground without much trouble, while pure copper remains malleable. Metal samples as a rule should be test-ground.
When a sample initially resists grinding, it may not be because it is “ungrindable.” Many such samples respond to the strategies of reducing the sample volume, increasing grinding time, and even lengthening the pre-cooling period to 30 minutes or so. Successes have also been scored by using “filler” grinding agents such as detergent and quartz sand.
What are the limits of cryogenic grinding?
As with samples ground at room temperature, those processed cryogenically vary enormously in their “grindability,” and it is difficult to predict the optimum sample size, chilling time, or grinding time. In addition, a given sample material may exist in several forms, some of which are easy to grind while others are very difficult. For example, polypropylene is supplied to molders as small pellets, but can be made into thin films or fibers; the pellets grind fairly easily, as they become rigid when chilled, but the films and fibers may remain flexible and become difficult to grind cryogenically.
Not every substance which is difficult to grind at room temperature can be pulverized by cryogenic milling. For this reason we at SPEX SamplePrep recommend that you discuss your samples and grinding requirements with one of our specialists before selecting a mill. If there is any question about whether a sample can be ground in a Freezer/Mill we will request that a portion be submitted for test-grinding.
What type of grinding vials are offered for the Freezer/Mills®?
SPEX SamplePrep Grinding Vials are now available in four different sizes. Microvials have a sample capacity of 0.1 – 0.5 grams; Small Grinding Vials have a capacity of 0.5 – 4.0 grams. Mid-Size Grinding Vials have a sample capacity up to 25 grams and the Large Grinding Vials can accommodate up to 50 grams.
The basic grinding vials include the 6751 Small Grinding Vial Set, 6881 Mid-Size Grinding Vial Set, and the 6801 Large Grinding Vial Set. They all consist of a steel impactor and end plugs with a polycarbonate center section. Steel is ideal for the impactor and end plugs as it is the only magnetic material that is easily manufactured and holds up well at liquid nitrogen temperature. The polycarbonate center section is surprisingly durable, and has two practical advantages: when chilled it forms a tight seal with the end plugs, and it allows visual inspection of the ground sample. Stainless steel center sections are available for cases where contamination with polycarbonate is not acceptable.
The 6753 Microvial Set is ideal for grinding smaller samples. Each individual microvial consists of an impactor, center cylinder, and end plugs all made of steel. A perforated polycarbonate microvial holder, positions three Microvials in the Freezer/Mill.
The new Poly-Vials include the 6761 Small Poly-Vial Set and the 6885 Mid-Size Poly-Vial Set. They consist of polycarbonate end plugs and center cylinder with a polycarbonate-encapsulated steel impactor. They are used for milling delicate plant and animal tissues with no metallic contamination.
Another new product is the Cr-Free Vial designed for RoHS/WEEE testing of electronic components. This includes the 6771 Small Cr-Free Vial Set, 6883 Mid-Size Cr-Free Vial Set, and the 6871 Large Cr-Free Grinding Vial Set. They consist of a polycarbonate center cylinder with end plugs and an impactor made of Cr-free ASTM 06 steel.
What is the sample capacity of the Freezer/Mill’s® grinding vials?
The 6770 Freezer/Mill® with the 6751 Small Grinding Vial Set has a sample volume limit of about 5 mL; bulkier samples may restrict movement of the impactor. For efficient grinding, typical sample volume is 1 to 2 mL, corresponding to weights of 1 to 2 grams for polymers and 2 to 4 grams for bone. Specialized grinding vials with similar capacity are the 6761 Small Poly-Vial Set for metal-free grinding of delicate samples, and the 6771 Small Cr-Free Vial Set for grinding electronic components without adding chromium.
The 6753 Microvial Set includes three 6753V Microvials. Each Microvial can hold a small amount of sample, typically between 0.1 – 0.5 grams.
The 6870 Large Freezer/Mill® with the 6801 Large Grinding Vial Set has at least 50 mL maximum sample capacity, 10 times that of the 6770 Freezer/Mill®. Typical sample volumes are 10 to 20 mL, equivalent to weights of 10 to 20 grams for polymers and 20 to 40 grams for bone. The new line of Mid-Size Vials has about half the capacity of the 6801 vial, and includes the 6885 Mid-Size Poly-Vial Set, the 6883 Mid-Size Cr-Free Grinding Vial Set, as well as the standard 6881 Mid-Size Vial Set. The 6870 Large Freezer/Mill® can also hold up four 6751, 6761, and 6771 vials for simultaneous grinding of multiple smaller samples. Can the Freezer/Mills® be used to grind samples for RoHS/WEEE compliance testing? The Restriction of Hazardous Substances (RoHS) and Waste Electrical and Electronic Equipment (WEEE) Directives of the European Union were introduced to minimize the accumulation of hazardous waste in landfills from the disposal of electrical and electronic equipment. The concentrations of hazardous substances such as lead, cadmium, mercury, chromium VI, polybrominated diphenylethers (PBDEs), and polybrominated biphenyls (PBBs) are restricted in electrical and electronic products and/or components.
RoHS/WEEE states that if the component can be mechanically separated, then each component is subject to the RoHS limits. The definition of exactly what this means is an ongoing process. However, one thing is certain; in order to get an accurate analytical result, these products and components must be reduced to homogenous, representative samples. Many components such as circuit boards, wire, solder, polymers and resins are difficult if not impossible to grinding using traditional methods. Cryogenic grinding in the 6770 Freezer/Mill® and the 6870 Large Freezer/Mill® is often the easiest way to homogenize these materials.
The end plugs and impactor of the standard Freezer/Mill® grinding vials are made of 440C stainless steel. This type of steel contains 16-18% Cr metal which could potentially contaminate the samples. This poses an issue because Chromium VI (a restricted substance) cannot be distinguished from Cr metal by XRF, ICP, and other common analytical techniques. Hence the new Cr-Free Grinding Vials, whose end plugs and impactor are made from chromium-free steel, were designed to insure that any Cr found in a sample originated there, and not in the grinding vial.
A detailed Application Note describing the use of the Freezer/Mill® for RoHS/WEEE is available.
What are the principles behind the grinding action used in the Freezer/Mills®?
SPEX SamplePrep Freezer/Mills are cryogenic mills that utilize liquid nitrogen as a coolant. The Freezer/Mill technology has been field proven since the 1960’s. Chilling materials in liquid nitrogen (at temperatures approaching - 200°C) has two important consequences for sample preparation: it embrittles flexible samples so they can be pulverized by impact milling, and it preserves structural and compositional aspects usually damaged or lost during room-temperature grinding.
The Freezer/Mill incorporates an insulated tub into which liquid nitrogen is poured. The grinding mechanism is a magnetic coil assembly suspended in the liquid nitrogen bath. Each sample is placed in a closed grinding vial along with a steel impactor, and the vial is then inserted in the coil assembly and lowered into the liquid nitrogen. When the sample is thoroughly chilled – usually a matter of 10 to 15 minutes – grinding begins. The magnetic coil shuttles the impactor rapidly back and forth, pulverizing the sample against the end plugs of the vial at speeds up to 30 impacts per second. When the grinding cycle is complete, the vial is removed from the Freezer/Mill, emptied, and cleaned.
How have the Freezer/Mills® been used in the field of medical research?
Medical schools and research hospitals have long used Freezer/ Mill technology in a variety of unconventional projects. One is the pulverizing of fresh, sterilized bone to use as a cement in joint-replacement surgery. The tiny bone fragments act as growth nuclei to stimulate the formation of bone around prosthetic implants. Another is the homogenizing of heart tissue to smear on slides as a culture medium. Freezer/Mills have even been used to grind implant materials to a fine powder which can be injected into live subjects for allergy and toxicity testing. At dental schools cryogenic grinding is used to pulverize fresh teeth without degrading them through heating. The overall possibilities in the medical field seem endless.
A wide range of Application Notes which discuss the various Freezer/Mill® applications in more detail are available.
How can the Freezer/Mills® be used in the recovery of volatile compounds?
Coal, petroleum shale, waxes, and many other organic materials contain light-molecular-weight fractions which are quickly driven off when their matrix is pulverized at room temperature. Grinding these materials in Freezer/Mills insures the retention of volatile components, which can be concentrated later by heating the ground sample in a gas trap.
A wide range of Application Notes which discuss the various Freezer/Mill® applications in more detail are available.
How can the Freezer/Mills® been used for mineralogical studies?
The structures of certain minerals, notably clays, micas, and fibrous amphiboles, can be difficult to distinguish by X-ray diffraction because they are subject to matting and preferred orientation when pulverized by normal means, with unusually soft minerals there can also be distortion of the crystal lattice due to impact. When chilled during grinding in SPEX SamplePrep Freezer/Mills, these minerals can often be broken up more completely, exhibiting more nearly random orientation of grains and maintaining greater structural integrity.
A wide range of Application Notes which discuss the various Freezer/Mill® applications in more detail are available.
How are the Freezer/Mills® beneficial for pharmaceutical testing and drug analysis?
The complex molecules present in drugs, and their metabolites, are of considerable interest to both pharmaceutical researchers and crime labs. There are many cases where it is important to be able to distinguish between different closely related isomers. Unfortunately, many such compounds are quickly degraded by the pressure and heat accompanying room-temperature milling. Preparation of key samples, whether the compounds themselves or tissues which may contain them, is greatly facilitated by cryogenic grinding in SPEX SamplePrep Freezer/Mills.
A wide range of Application Notes which discuss the various Freezer/Mill® applications in more detail are available.
How can the Freezer/Mills® be used for trace metal analysis?
Low levels of toxic heavy metals such as cadmium, chromium, and mercury are known to have profound effects on human health, whether present in substances we ingest or in paint, fabric, plastic, and other materials with which we (or our food and water) have contact. Many such samples, from fish scales and bovine liver to the plastics used in food packaging and children’s toys, have to be prepared for analysis; grinding with SPEX SamplePrep Freezer/Mills is often the simplest way. Medical examiners, pathologists, and even anthropologists may be concerned with clues such as the concentration of chromium in bones or the accumulation of arsenic in hair and fingernails; here again, cryogenic milling is often the best way of pulverizing such samples for extractions, dissolutions, or direct analysis.
A wide range of Application Notes which discuss the various Freezer/Mill® applications in more detail are available.
What landmark studies have used the Freezer/Mills® for DNA and RNA extractions?
Human bones and teeth, especially when fresh, are difficult to pulverize with normal mills. However, skeletal material can be ground cryogenically and DNA extracted from the powder, whether the remains are recent or very old. Forensics labs use Freezer/Mills to isolate the DNA of crime victims or war casualties when medical and dental records are inadequate. Recently this approach was used to help identify the bones of Russia’s Czar Nicholas II and his family.
Paleoarchaeologists are beginning to plot the DNA of more ancient human remains, again using cryogenic grinding and PCR (polymerase chain reaction) amplification. A SPEX SamplePrep Freezer/Mill was employed to prepare bone fragments from the 5300-year-old “Ice Man” found in the Alps in 1991. RNA in fresh plant tissue is degraded or destroyed by grinding at room temperature. However, Freezer/Mills preserve RNA for analysis by keeping it below –70° C during grinding.
A wide range of Application Notes which discuss the various Freezer/Mill® applications in more detail are available.
What are the applications for the Micro Hammer-Cutter Mill?
The Micro Hammer-Cutter Mill takes up a minimum amount of bench space, and it will handle a range of samples that would ordinarily require several different mills. Dried plants and roots, paper and cloth, soil samples, coal and peat, chemicals and soft rocks all grind quickly with little loss of sample. Specialized applications include preparing grains and banana leaves for extraction, grinding wood samples for XRF pelletizing, reducing the particle size of stearic acid granules, and powdering such diverse substances as crab shells and dried marsh grass for trace element analysis.
In Great Britain the Micro Hammer-Cutter Mill is widely employed for the Stenvert Wheat Hardness Test.* This rapid and relatively simple procedure involves releasing 20 g of sample into the mill’s grinding chamber, and recording the time required to grind 17 mL. Because the correlation between grinding time and grain hardness is direct and consistent, the method is much simpler than other standard tests. The mill’s high speed and rapid throughput allow limited medium-to-coarse grinding of flexible polymers, soft metals, and temperature-sensitive materials. In many cases, precooling of the sample is advisable.
* “Grinding Resistance; a Simple Measure of Wheat Hardness.” N.L. Stenvert, Flour & Animal Feed Milling. July 1974. Pages 24-27.
What is included with the purchase of the Micro Hammer-Cutter Mill?
The 5200 Micro Hammer-Cutter Mill is supplied with twelve plastic 35 mm collecting tubes and rack, a set of cleaning tools, and three hardened steel screens (mesh sizes 2.0 mm, 1.5 mm, and 1.0 mm). Additional screens, including a 3.0 mm screen for coarse grinding and three smaller screens of 0.8 mm, 0.5 mm, and 0.2 mm, are offered separately.
NOTE: When specifying screen size, remember that the average particle size of the ground material that passes through a screen is always much smaller than the holes in that screen. For example, a typical medium-hard sample passed through the 0.5 mm screen yields a particle distribution in which 95% of the material is ≤100 mesh (particle size less than 0.15 mm) and 40% is ≤200 mesh (less than 0.07 mm).
What are the applications for the 5100 Mixer/Mill®?
The 5100 Mixer/Mill® is ideal for grinding small amounts of brittle samples such as minerals, rocks, or glass. It has even been used for grinding gallstones. The 5100 Mixer/Mill® can also be used for mixing powders and slurry grinding and is commonly used to blend samples with KBr for IR analysis.
What types of grinding vials are available for the 5100 Mixer/Mill®?
The 5100 Mixer/Mill’s continuously adjustable jaws accept vials from 1 in. (25.4 mm) to 21⁄2 in. (63.5 mm) long and up to 3⁄4 in. (19 mm) in diameter without adapters. It holds three 1⁄2 in. (12.7 mm) diameter or two 3⁄4 in. (19 mm) diameter vials. Vials are available in plastic (polystyrene and polycarbonate), hardened and stainless steel, agate, and tungsten carbide. All of the vials except for the agate are able to accommodate slurry grinding.
What are the principles behind the grinding action used in the 5100 Mixer/Mill®?
The high grinding and mixing efficiency of the 5100 Mixer/Mill is a result of its three-dimensional action. A one-inch (25.4 mm) component of motion along the axis of the vial is complemented by two motions at right angles to the vial axis: a 3⁄16 in. (4.8 mm) horizontal movement and a 1⁄4 in. (6.35 mm) vertical oscillation. The resulting action is consistent with the general shape and size of the vials. That is, at every stroke there is an impact at the end of the vial – over 100 per second – to crush the material rapidly and reproducibly.
What are the applications for the 8000M Mixer/Mill® and 8000D Dual Mixer/Mill®?
8000 Series Mixer/Mills have been used for pulverizing rocks, minerals, sand, cement, slag, ceramics, catalyst supports, and hundreds of other brittle, often hard samples. Early on, the Mixer/Mill was used to grind samples, and then blend them with graphite for arc/spark spectroscopy. Now similar samples are ground and then blended with binder before being pressed into samples disks for XRF. The vigorous motion of the clamp is also excellent for making emulsions such as paints, inks, and pharmaceuticals. The 8000M Mixer/Mills have also achieved notoriety for their ability to mechanically alloy small quantities of materials.
What type of safety features are the 8000M Mixer/Mill® and 8000D Mixer/Mill® equipped with?
The 8000 Series Mixer/Mill’s rugged and durable construction is the reason why many of the original mills are still in use. A steel cabinet protects the entire clamp mechanism and vials. Both of the 8000 Series Mixer/Mills are equipped with safety interlocks so that they cannot be operated with the lid open. Each clamp has a lock nut to prevent it from loosening while the mill is running. The motors are also equipped with a thermal overload protector and both of the 8000 Series Mixer/Mills are CE Approved.
What is the difference between the 8530 Shatterbox® and the 8500 Shatterbox®?
The full-sized 8530 Enclosed Shatterbox is CE-Approved and has a soundproof enclosure to help reduce noise levels. It also features a safety interlock system, LCD display with a push button membrane switch, and lockable casters. The 8530 Enclosed Shatterbox is ideal for labs concerned with minimizing noise and maximizing safety.
The 8500 Shatterbox, offers the same grinding performance as 8530 but without the timer and cabinet. Instead, it has a perforated metal skirt to provide ventilation for continuous operation, and a rubber cover protects against dust. It also includes an anti-skid wood/rubber floor mount. The 8500 Shatterbox was the original SPEX SamplePrep swing mill. It was developed for cement plants and steel mills with open, noisy lab conditions and is still used in many locations where the working environment requires a rugged, simple mill.
What are the applications for the Shatterbox®?
Shatterboxes typically grind cement mix, rocks, slags, soils, ceramics, and ores, but have been used for hundreds of other materials including sulfur pellets, dried marsh-grass, and pharmaceuticals.
What types of grinding containers are available for the Shatterbox®?
The standard grinding containers, with a nominal volume of about 100 mL, is available in hardened steel (8501), tungsten carbide (8504), alumina ceramic (8505), and zirconia ceramic (8506). Typical grinding loads for samples such as cement, rock, or slag are 50 grams for the steel and tungsten carbide containers and 30 grams for the ceramic containers. Note that the actual capacity of the containers is much higher, and (for example) the steel container has been used for as little as 4 grams and as much as 100 grams. However, grinding efficiency decreases as the container becomes more tightly packed.
There are also small grinding containers made of hardened steel (8507) and tungsten carbide (8508), which can be run either one or three at a time with the 8507R Rack. These grinding containers have about a fifth the capacity of the standard grinding containers and a typical sample size of 10 grams.
An oversize steel grinding container (8521) is also available and has approximately a 150 mL capacity. This corresponds to a typical sample size of 75-100 grams. The 8525 Transporter can be used to move the heavier grinding containers (8501, 8504, 8521) in and out of the Shatterbox.
What are the principles behind the Shatterbox® grinding action?
The Shatterbox swings a dish-shaped grinding container in a tight, high-speed horizontal circle. Inside the container are the sample, a puck, and (in most containers) a ring. As these grinding elements swing free inside the container, the sample is rapidly crushed between the walls of the container, puck, and ring, and further reduced by the millstone-like action of the puck and ring against the container floor. Grinding times are usually between two and five minutes, with resultant particle size well below 200 mesh (approximately 50 microns). With grinding aids, smaller samples can be reduced below 10 microns.
What type of controls does the Shatterbox® have?
The 8500 Shatterbox® can be plugged into a standard lab timer that is not included with the mill.
The 8530 Enclosed Shatterbox® features a new LCD display with an environmentally safe, push-button membrane switch. Electronic controls allow programmed running times up to 10 minutes. As the Shatterbox runs, the timer display counts down the minutes and seconds remaining. A “pause” function allows interruption of a grinding cycle.
What type of safety features is the Shatterbox® equipped with?
The 8500 Shatterbox contains a motor protected by a perforated shield to allow ample air-cooling for continuous running, and a rubber “skirt” shields the drive mechanism but is easy to move aside when the drive belts need to be replaced. It is shipped with a rubber matted plywood base to prevent it from “walking” during operation. The old screw-down clamp has been replaced with the cam-activated clamp to accommodate all SPEX SamplePrep grinding containers.
The 8530 Enclosed Shatterbox includes a sound-insulated steel cabinet with lockable casters, with which the mill can be moved about the lab and then fixed in place. Safety features include a safety interlock and gas cylinders for the lid. The interlock holds the lid closed whenever the mill is running, and the cylinders control movement of the lid when it is closed or opened.
Can the Freezer/Mills® be used to grind samples for RoHS/WEEE compliance testing?
The Restriction of Hazardous Substances (RoHS) and Waste Electrical and Electronic Equipment (WEEE) Directives of the European Union were introduced to minimize the accumulation of hazardous waste in landfills from the disposal of electrical and electronic equipment. The concentrations of hazardous substances such as lead, cadmium, mercury, chromium VI, polybrominated diphenylethers (PBDEs), and polybrominated biphenyls (PBBs) are restricted in electrical and electronic products and/or components.
RoHS/WEEE states that if the component can be mechanically separated, then each component is subject to the RoHS limits. The definition of exactly what this means is an ongoing process. However, one thing is certain; in order to get an accurate analytical result, these products and components must be reduced to homogenous, representative samples. Many components such as circuit boards, wire, solder, polymers and resins are difficult if not impossible to grinding using traditional methods. Cryogenic grinding in the 6770 Freezer/Mill® and the 6870 Large Freezer/Mill® is often the easiest way to homogenize these materials.
The end plugs and impactor of the standard Freezer/Mill® grinding vials are made of 440C stainless steel. This type of steel contains 16-18% Cr metal which could potentially contaminate the samples. This poses an issue because Chromium VI (a restricted substance) cannot be distinguished from Cr metal by XRF, ICP, and other common analytical techniques. Hence the new Cr-Free Grinding Vials, whose end plugs and impactor are made from chromium-free steel, were designed to insure that any Cr found in a sample originated there, and not in the grinding vial.
A detailed Application Note describing the use of the Freezer/Mill® for RoHS/WEEE is available.
What is the procedure for using Vertrel® XF as a grinding aid?
3650 Vertrel® XF, a DuPont product sold as a cleaning fluid, is finding increased acceptance as a grinding aid. A fluorocarbon fluid, it prevents sample caking during grinding, and quickly evaporates from an open grinding container without leaving any residue. Our experience is that the “grindability” of almost any sample is enhanced by the use of Vertrel XF, contamination is lowered, and the grinding container is easier to clean. Typical XRF samples such as cement, rock, clinker, and similar material can be routinely ground below 10 microns. Vertrel XF also lowers contamination levels from the grinding container.
The technique that follows was pioneered by John Anzelmo and colleagues at Bruker AXS and is here adapted for SPEX SamplePrep equipment: In an 8501 Hardened Steel Grinding Container load together 10 grams of sample, 2.5 grams of 3642 Cellulose Binder or 3644 Ultrabind®, and 7 mL of 3650 Vertrel® XF. Grind in an 8530 Enclosed Shatterbox for 2.0 minutes then open the grinding container in a hood until the Vertrel XF has evaporated. Prepare a 3614 40mm Evacuable Pellet Die Set with a flared 3617 38 mm Spec-Cap®, and transfer the ground sample/binder powder to the die. Press at 20 tons for 0.3 minutes in a 3635 Automated X-Press.
Reference Anzelmo, John; Seyfarth, Alexander; and Arias, Larry (2001). Approaching a Universal Sample Preparation Method for XRF Analysis of Powder Materials. Advances in X-ray Analysis, Vol. 44, JCPDS – International Centre for Diffraction Data, Newtown Square PA.
What publications reference the Mixer/Mill® for mechanical alloying?
Over the years nearly one hundred articles have been published in refereed scientific journals regarding the SPEX SamplePrep Mixer/Mill and its use for mechanical alloying. This includes mechanical alloying techniques, evaluations of grinding vial materials, and numerous other topics. The following publication list is intended to highlight the more recent publications that we are aware of and is not intended to be comprehensive. If you are considering the Mixer/Mill for your own mechanical alloying application, we strongly encourage you to do your own search for applicable publications and references.
Effect of the heating rate on crystallization behavior of mechanically alloyed Mg50Ni50 amorphous alloy. Aydinbeyli, N., Nuri Celik, O., Gasan, H., Aybar, K. International Journal of Hydrogen Energy, Vol. 31, Issue: 15, December, 2006. pp. 2266-2273. Effect of ball milling on simultaneous spark plasma synthesis and densification of TiC-TiB2 composites. Locci, A.M., Orru, R., Cao, G., Munir, Z.A. Materials Science and Engineering A, Vol. 434, Issue: 1-2, October 25, 2006. pp. 23-29. Temperature of the milling balls in shaker and planetary mills. Takacs, L., McHenry, J. S. Journal of Materials Science, Vol. 41, Issue: 16, August 2006. pp. 5246 – 5249. Modeling of comminution processes in Spex Mixer/Mill. Concas, A., Lai, N., Pisu, M., Cao, G. Chemical Engineering Science, Vol. 61, Issue: 11, June, 2006. pp. 3746-3760. Effect of mechanical alloying conditions on the microstructure evolution and electrode characteristics of Mg63Ni30Y7. Khorkounov, B., Gebert, A., Mickel, Ch., Schultz, L. Journal of Alloys and Compounds, Vol. 416, Issue: 1-2, June 8, 2006. pp. 110-119. A study of mechanical alloying processes using reactive milling and discrete element modeling. Ward, T.S., Chen, W., Schoenitz, M., Dave, R.N., Dreizin, E.L. Acta Materialia, Vol. 53, Issue: 10, June, 2005. pp. 2909-2918. Microstructural evolution during mechanical alloying of Mg and Ni. Rojas, P., Ordonez, S., Serafini, D., Zuniga, A., Lavernia, E. Journal of Alloys and Compounds, Vol. 391, Issue: 1-2, April 5, 2005. pp. 267-276. Mechanical milling of magnesium powder. Hwang, S., Nishimura, C., McCormick, P.G. Materials Science and Engineering: A, Vol. 318, Issue: 1-2, November, 2001. pp. 22–33. Formation of supersaturated solid solutions by mechanical alloying. Huang, B.-L., Perez, R.J., Lavernia, E.J., Luton, M.J. Nanostructured Materials, Vol. 7, Issue: 1-2, January 2, 1996. pp. 67-79. Synthesis of nanocrystalline Fe-B-Si powders. Perez, R.J., Huang, B.-L., Crawford, P.J., Sharif, A.A., Lavernia, E.J. Nanostructured Materials, Vol. 7, Issue: 1-2, January 2, 1996. pp. 47-56.
Why is the Mixer/Mill® considered a high-energy ball mill?
SPEX SamplePrep Mixer/Mills are a variant of the ball mill or jar mill, which grinds samples by placing them in a container along with one or more grinding elements, and imparting motion to the container. The containers are usually cylindrical; the grinding elements are most often balls, as is the case with the Mixer/Mills, but may be rods, cylinders, or other shapes. Generally the containers and grinding elements are made from the same material. As the container is rolled, swung, vibrated, or shaken, the inertia of the grinding elements causes them to move independently, into each other and against the container wall, grinding the sample. Variations of the “ball mill” range from laboratory mills with a sample capacity of a gram or less to large industrial mills with a throughput of tons per minute.
SPEX SamplePrep Mixer/Mills can be described as laboratory scale, high-energy ball mills. They are designed to pulverize a sample rapidly while mixing it homogeneously—an approach long known to be effective in preparing samples for emission spectroscopy and XRF spectrometry. SPEX SamplePrep Mixer/Mills are also widely used for blending powders and making emulsions. Due to its high-energy action the SPEX SamplePrep 8000 Series Mixer/Mills have recently become indispensable for nanomilling and mechanical alloying
What types of controls and safety features is the 5100 Mixer/Mill® equipped with?
The 115 V/60 Hz version of the 5100 Mixer/Mill has a pushbutton, resettable 30-minute timer. The 230 V/50 Hz version has a push-button, resettable 72-minute timer.
The rugged construction of the 5100 Mixer/Mill ensures a long life of heavy work. The steel housing protects the entire clamp mechanism and vials and the lid is equipped with a locking latch.
Mixing and Blending
What type of controls does the 8000M Mixer/Mill® and 8000D Dual Mixer/Mill® have?
The electronic timer of the 8000 Series Mixer/Mills displays the programmed running time in minutes and seconds. While the mill is operating, the timer also counts down the amount of time left in the run. Push-button controls include start, stop and pause functions as well as timed programming. The timer is factory-set for a maximum of 100 minutes but this may be extended to 1,000 or 10,000 minutes for special applications such as mechanical alloying with the installation of a special chip (39450 Chip for Extended Running Time). Prolonged continuous operation of Mixer/Mills requires special maintenance and warranty restriction may apply. Contact SPEX SamplePrep for details.
Pricing Details
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For all other countries, please add items to your cart and submit to SPEX SamplePrep for a quote. Registration and contact information will be required to complete the quote submission process. A sales representative from SPEX SamplePrep or an authorized distributor will review the quote request and contact you with pricing.
For additional information or assistance, please contact us or find a distributor in your country.
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