Ring and Puck Mills

A Ring and Puck Mill is a laboratory sample mill used for the rapid pulverization of hard, brittle materials to a fine powder. The device uses grinding sets which consist of a grinding container equipped with one puck-shaped grinding element, additionally one or two rings can be used. During operation, the grinding container is subjected to high-speed rotational movement. The plate with the grinding set is subjected to circular horizontal vibrations. The centrifugal force acting on the grinding rings and the puck results in extreme pressure and frictional forces acting on the sample, producing analytical fineness in 1-3 minutes. Ring and Puck Mills are widely used in geological, mining, and metallurgical laboratories for sample preparation before analysis, offering a quick and effective means to prepare samples for X-ray diffraction, spectroscopy, or other analytical techniques.

Ring and Puck Mill or Vibratory Disc Mill?

Another term for Ring and Puck Mill is Vibratory Cup Mill or Vibratory Disc Mill. Retsch offers two different models of these instruments. The larger one, the Vibratory Disc Mill RS 300, works with grinding sets up to 2000 ml. The grinding sets 800 ml, 1000 ml and 2000 ml truly work with a disc. The 400 ml grinding set and the 50 ml grinding set use a puck, the 400 ml grinding set also has a ring. Thus, also the RS 300 can be regarded as a Ring and Puck mill or a Vibratory Cup Mill. 100 ml and 250 ml grinding sets of the RS 200, both coming with a ring and a puck, can be used in the RS 300 with adapters. Thus, the RS 300 is a true Ring and Puck mill.

Function principle Vibratory Disc Mill RS 200

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Functional Principle Ring and Puck Mills

Puck, ring or disc used in Retsch Vibratory Disc Mill / Ring and Puck Mill

	50 ml	100 ml	250 ml	400 ml	800 ml	1000 ml	2000 ml
RS 200	Puck	Puck & Ring		-	-	-	-
RS 300	Puck	Used from RS 200 with adapter		Puck & Ring	Disc	Disc	Disc

Grinding jar RS 200

High-quality grinding sets RS 300

Use of Ring and Puck Mills:

Geology: For the analysis of rocks, minerals, and sediments, ring and puck mills are used to achieve a fine, homogeneous powder. This is crucial for determining the composition and properties of geological samples.
Cement industry: In quality control and compositional analysis of clinker and raw materials, the mills ensure the samples are adequately prepared for accurate analysis.
Mining: For ore grade control and exploration, pulverizing ore samples is a critical step in the assay process, allowing for the determination of metal content.
Metallurgy: In the study of metals and their properties, including failure analysis, ring and puck mills play a role in preparing samples for microscopic examination and analysis.
Environmental Testing: Soil and sediment samples can be pulverized for the analysis of contaminants, nutrient levels, and other environmental parameters.

Typical Sample Materials

RETSCH’s Ring and Puck Mills rapidly pulverize materials such as cement, cement clinker, ceramics, coal, coke, concrete, corundum, glass, metal oxides, minerals, ores, silicate, slag, soil, etc.

slag

electronic scrap

iridium

dolomite

Advantages of Ring and Puck Mills

Uniformity: The grinding mechanism ensures that the sample is pulverized uniformly, resulting in a fine, homogeneous powder that is ideal for accurate analytical results e.g. via XRF.
Efficiency: Ring and puck mills are capable of rapidly processing small to medium-sized samples, which is particularly beneficial in laboratories with high throughput requirements.
Versatility: Although primarily used for hard, brittle materials, advancements in ring and puck mill designs have expanded their application to include softer materials and fibrous substances when the appropriate grinding containers and rings are used.

Sample Pulverization with Ring and Puck Mills

RETSCH’s RS 200 or RS 300 are the instruments of choice for processing hard and brittle samples such as limestone or clinker prior to XRF analysis. Due to centrifugal forces the grinding ring and puck act with high impact and friction on the sample, allowing both mills to produce a final fineness down to 20 µm, depending on the sample material. With this size reduction principle, the required analytical fineness is usually achieved within seconds. This is advantageous for quality control processes where the analysis results are needed quickly, e.g. for product approval.

The grinding sets available in sizes up to 250 ml for the RS 200 accept maximum initial particle sizes of 15 mm and perform circular oscillations with 700 to 1500 rpm. Operating the mill is very ergonomic with carry handles for the grinding sets, a quick-action clamping system and a rail on which the grinding sets easily slide into the correct position. Application example - fine grinding of cement clinker: 200 ml of a sample with particle sizes up to 12 mm were milled in the RS 200 at 1500 rpm, using a grinding set of 250 ml stainless steel. After only 60 seconds, a fineness of 85 microns was achieved.

The RS 300 is used for the same applications as the RS 200 but accepts initial particle sizes of up to 20 mm. A maximum of 4 samples may be processed simultaneously, depending on the accessories used. The RS 300 accepts grinding set weights of up to 30 kg and sample volumes up to 2000 ml. The pneumatic grinding-jar clamping and the optional AutoLifter for heavy grinding sets ensure convenient and safe handling. Application example - fine grinding of raw cement: 2000 ml of a cement clinker sample were pulverized in the RS 300, using a grinding set of 2000 ml hardened steel. The initial particle size of the sample was approx. 35 mm but due to the brittle nature of the material, it was no problem to process it in the RS 300 without preliminary size reduction. After 6 min, a fineness of 100 microns was achieved. The RS 200 pulverizes this material much faster but would require a much smaller feed size. So regardless of the user’s requirements, RETSCH offers a suitable mill.

Degree of homogenization and reproducibility in both Retsch Ring and Puck Mills

The degree of homogenization of both mills was compared by grinding a mixture of two different materials in the RS 200 and the RS 300. In the RS 300, 950 g quartz and 50 g tantalum pentoxide (Ta2O5) were milled for 4 min at 912 rpm in a 2000 ml grinding set of hardened steel. Samples were then taken from different locations in the grinding jar, one at 120°, one at 240° and one at 360° with different depths (surface, center and bottom). The same sampling was done after grinding 118.75 g quartz and 6.25 g Ta2O5 for 1 min at 1500 rpm in a 250 ml grinding set of hardened steel in the RS 200. The achieved fineness of D 97 = 100 µm was identical in both the RS 300 and the RS 200. The pulverized samples were then mixed with Licowax® and pressed in 40 mm aluminum cups with the Pellet Press PP 40. The settings were 20 t pressure and 20 secs.

The pellets were analyzed using the Spectro Xepos P spectrometer. The main focus was on the concentration of Tantalum in the pellets taken from the different locations in the grinding jar. To represent the original quartz-tantalum mixture each pellet should contain 50 mg Ta2O5 per g or 41 mg Ta per g. All samples showed values very close to this calculated value. Very good homogeneity was observed, all samples showed comparable negligible variations of the tantalum content, independent of the location of sampling or the mill used. The relative standard deviation with a maximum of ±0.54 mg/g was very low and the overlay spectra of all measurements showed very good matching.

Pellet Press PP 40

Measurement of Tantalum

RETSCH instruments are used in science and industry for the sample preparation for a wide range of different analytical methods as well as for particle size analysis in the context of production control and quality monitoring.

RETSCH meets the ever-increasing demands in these fields with a clear product philosophy: "The whole is greater than the sum of its parts"

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