TM 300 DRUM MILL INTRODUCTION
BENEFITS AT A GLANCE
- Powerful and quick processing of large quantities up to 9 l
- Suitable for dry and wet grinding
- Standard drum sizes range from 5 l to 43.4 l
- Variable speed and reproducible results
- Suitable for long term grindings
- Ball and rod modules available
- Ideal for upscaling tests in mechanochemistry
- Perfect seal with single-screw lids
SAFE AND CONVENIENT OPERATION
The TM 300 stands out for its user-friendly features. The easy tilt mechanism facilitates the swift and uncomplicated emptying of the grinding jar. The removable sample collector simplifies the sample retrieval process, making it convenient for operators to access their collected materials.
The solid noise-protection hood contributes to a quieter and more comfortable working environment.
The TM 300 is equipped with an emergency switch, providing a quick and reliable means to halt the milling process in case of unforeseen circumstances, underscoring the commitment to user safety.
The redesigned drums and drum covers of the TM 300 feature improved handling, allowing the lid to be secured with just one screw for a perfect seal, even during wet grinding.
PARAMETER SETTING
Process parameters like grinding time or start/stop are conveniently set via the TM 300’s large display interface. Settings include:
- Variable speed from 1 to 80 rpm
- Grinding time of up to 99:59:59 h:min:s
- Rotation direction, e. g. to reduce caking effects
- Programmable interval & break options for temperature-sensitive samples
- Delayed start function
ACCESSORIES FOR EFFECTIVE GRINDING
Catering to various application needs, the TM 300 offers standard grinding drums ranging from 5 to 43.4 liters. This ensures that the mill is adaptable to a wide spectrum of processing tasks.
An optional separation grid provides convenient separation of balls and sample after the grinding process. It is suitable for grinding balls sized 10, 20 or 30 mm. A connection for dust extraction prevents release of dust.
The grinding jar comes equipped with a gasket, ensuring a secure seal for loss-free milling operations. This feature not only enhances the efficiency of the process but also minimizes the risk of material waste.
DRUM FILLING LEVEL FOR GRINDING BALLS AND RODS
While the maximum sample feed size depends on properties like hardness and breaking behaviour, a particle size of approximately 5 mm is ideal for the TM 300. Larger sizes are acceptable but should not exceed 15 mm. For sample lumps which break very easily or for deagglomeration effects, a feed size between 20 and 30 mm is feasible. For such easy-to-process samples, the sample filling level may be increased to 9 l.
If special drums of stainless steel 1.4404 in sizes 21.7 / 10 / 5 l together with grinding balls of steel 1.4404 are employed, it is possible to carry out wet grinding in the TM 300. The total filling volume for wet grinding may exceed the recommended amount for dry grinding. It may be helpful to use a large number of small grinding balls to increase friction.
5 DRUM POSITIONS FOR CONVENIENT HANDLING
The user can set the grinding drums in five different positions which are secured by a screw. This ensures easy filling and emptying of the drum but also improves the mixing and grinding process. The largest rod module of 43.4 l cannot be brought into the mixing position due to lack of space.
SPECIAL APPLICATION: BOND INDEX TEST
Another application area of the TM 300 is Bond Index Testing. The Bond Work Index is used to assess the grinding efficiency and to calculate the necessary grinding power when choosing comminution equipment in the design phase of, for example, a mining plant. Precise determination of BWI is crucial for the accurate design and estimation of costs linked to the comminution process in industries like cement, mining or steel.
Both the Ball Mill and the Rod Mill module can be used for the process. At least 15 to 20 kg sample material is required to simulate a closed grinding circuit.
BALL MILL MODULE
The Ball Mill Work Index (BWI) is used for the range from 2.1 mm down to 100 µm. The sample needs to be pre-crushed to particle sizes as defined below.
- Minerals: < 3.35 mm and sieved
- Drillcore: < 3.35 mm and sieved
- Half Drillcore: < 3.35 mm and sieved
The optimum number of grinding balls is 285. With the ball diameters varying due to wear, the overall number should be adjusted from time to time to ensure a total mass of 20.125 grams.
The grinding jar of the Bond Index Ball Mill measures 12” x 12” and has well-rounded corners.
ROD MILL MODULE
The Rod Mill Work Index (RWI) is used for particle size determination in a size range from 25 mm down to 2.1 mm. The sample needs to be pre-crushed to particle sizes as defined below.
- Minerals: < 12.50 mm and sieved
- Drillcore: < 12.50 mm and sieved
- Half a drillcore: < 12.50 mm and sieved
The grinding jar for the Bond Index Rod Mill is 12″ x 24″ in size and has a wave-shaped design.
THE SOLUTION FOR EFFICIENT AND SUSTAINABLE CO-CRYSTAL SYNTHESIS
The TM 300 is capable of meeting the demands of modern pharmaceutical manufacturing. This can be demonstrated by the example of the mechanochemical synthesis of rac-Ibuprofen:Nicotinamide co-crystals. The TM 300 is an environmentally friendly alternative to conventional solution-based methods. In just 90 minutes, 3.2 kg of co-crystals with a yield of 99 % were produced, using only minimal amounts of solvent in the so-called liquid assisted grinding (LAG) process. This reduces energy consumption compared to conventional methods and drastically minimizes environmental impact.
Conversion of rac-IBU. Blue plot: neat grinding approach with addition of 10 kg of balls (d = 10 mm) after 270 min and 10 kg of balls (d = 30 mm) after 360 min; addition of LAG additive EtOH after 510 min. Orange plot: LAG-assisted approach with EtOH added prior to the reaction and 20 kg balls 10 mm.
Results presented by the research group of Michael Felderhoff [1]
TM 300 enables mechanochemical processes to be carried out on a kilogram scale, opening up new possibilities for sustainable industrial manufacturing processes. Particularly interesting is the minimal metal abrasion – the measured values were well below concerning levels and significantly lower than, for example, in eccentric vibratory mills. The table shows the minimal abrasion values in the TM 300 during the test run.
Setup:
- 2,03 kg rac IBU; 1,20 kg NIC
- 10 l drum for wet grinding, 20 kg 10 mm grinding balls stainless steel
- LAG Ethanol 0.1 ml/g
- 60 rpm for 90 min
- 99 % yield
TYPICAL SAMPLE MATERIALS
RETSCH drum mills are true allrounders. They homogenize, for example: activated carbon, alloys, bentonite, bones, carbon fibers, catalysts, cellulose, cement clinker, ceramics, chemical products, clay minerals, coal, coke, compost, concrete, electronic scrap, fibers, gypsum, glass, hair, hydroxyl apatite, kaolin, lime stone, metal oxides, minerals, ores, paint and varnish, paper, pharmaceutical products, pigments, plants, polymers, quartz, seeds, semi-precious stones, sewage sludge, slag, soil, tissue, tobacco, waste, wood, etc.
FUNCTIONAL PRINCIPAL
In a drum mill the sample (usually pre-crushed material) is placed inside the drum with the grinding balls and subjected to external forces.
The Ball Mill is used for fine grinding of solid matter by impact and friction in dry condition. The drum, which contains the sample and grinding balls, rotates around a horizontal axis. Whereas particles break more easily when larger grinding ball diameters are used, smaller diameters lead to a substantially higher final fineness.
The ball and the rod mill basically have the same concept comprising either a 12”x12” jar with grinding balls or a 12”x24” jar with grinding rods.
The jar is attached to a rotating yoke which is driven by a motor and can be placed in three different positions: Upwards for loading, horizontal for grinding, downwards for discharging.
To carry out the Bond Index test the pre-defined number of grinding balls or grinding rods is required. The electronic control integrated in the drive is equipped with an overload protection and permits and controls different speeds.
During the grinding process the difference in speeds between the balls / rods and grinding jar produces an interaction between frictional and impact forces, which releases the required comminution energy. The interplay between these forces produces a very effective degree of size reduction.
TECHNICAL DATA
| Applications | pulverizing, mixing used as Bond Index Tester: quantification of grindability of ores and minerals |
| Field of application | agriculture, biology, chemistry, construction materials, engineering / electronics, environment / recycling, geology / metallurgy, glass / ceramics, medicine / pharmaceuticals |
| Feed material | soft, hard, brittle, fibrous – dry or wet |
| Size reduction principle | friction |
| Material feed size* | < 20 mm used as Bond Index Tester: < 3.35 mm with ball module / 12.50 mm with rod module |
| Final fineness* | < 20 µm used as Bond Index Tester: < 100 µm with ball module / 2,100 µm with rod module |
| Batch size / feed quantity* | minimum 1 l / maximum 9 l used as Bond Index Tester: min. 15 kg with ball module / min. 20 kg with rod module |
| Rotation speed | 1 – 80 min-1 used as Bond Index Tester: 70 min-1 with ball module / 46 min-1 with rod module |
| No. of grinding stations | 1 |
| Material of grinding tools | hardened steel, stainless steel used as Bond Index Tester: hardened steel |
| Grinding drum sizes | 5 l / 10 l / 21.7 l / 43.3 l used as Bond Index Tester: 21.7 l with ball module / 43.3 l with rod module |
| Setting of grinding time | digital |
| Drive | 3-phase asynchronous motor with frequency converter |
| Drive power | 0.75 kW |
| Electrical supply data | different voltages |
| Power connection | 1-phase |
| Protection code | IP 41 |
| Power consumption | ~ 1800 VA |
| W x H x D closed | 1500 x 1200 x 700 mm |
| Net weight | ~ 306 kg |
| Standards | CE |
*depending on feed material and instrument configuration/settings
