Optimised technologies for cryogenic grinding

Wilczek, Michael; Bertling, Jürgen; Hintemann, Damian

doi:10.1016/j.minpro.2004.07.032

Cited by 63 publications

(37 citation statements)

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“…In general low viscous solvents are advantageous and in certain cases [8] also the reduction of the process temperature (embrittlement of the polymer) may improve the grinding kinetics and reduce the energy needed to initiate fracture. Compared with typical mass specific energies needed for polymer grinding and typical minimum product particle size obtainable by dry grinding [1], one can conclude that the wet grinding process allows for smaller product particles (about one order of magnitude) at reasonable energy consumption. The wet grinding process is especially superior to dry grinding, if fine products (x 50,3 < 25 μm) are desired.…”

Section: Wet Grinding Of Pbtmentioning

confidence: 99%

“…polyamide (PA) are obtained by sophisticated precipitation methods that cannot be transferred readily to other types of polymers. As a more general method to produce fine polymer powders, frequently dry grinding has been applied [1][2][3][4][5][6][7]. Typically rotor impact mills or cutting mills are used and the polymer feed material is pre-cooled e.g.…”

Section: Introductionmentioning

confidence: 99%

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Production of PBT/PC particle systems by wet grinding

Schmidt¹,

Romeis²,

Peukert³

2017

AIP Conference Proceedings

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Study of the rheological behavior of polypropylene/polyethylene extruded mixture using an instrumented die AIP Conference Proceedings 1914, 040005 (2017) Abstract. Comminution of plastic or visco-elastic materials is known to be energy-intensive and costly. Typically impact mills, cutting mills and jet mills are applied for comminution and the feed material frequently is pre-cooled using liquid nitrogen or solid carbon dioxide. Therefore, especially the production of fine polymer particles by the aforementioned dry grinding methods is challenging. We demonstrate that wet grinding of polymers is a feasible approach for production of fine polymer particles that e.g. may be used as a starting material in a process chain for production of spherical polymer particles that can be used in in additive manufacturing. Wet comminution of polymers will be discussed for polybutylene terephthalate (PBT) and polycarbonate (PC). The products are thoroughly characterized by means of vibrational spectroscopy, X-ray diffraction and dynamic scanning calorimetry. The dependency of the grinding result on fundamental process parameters like stirrer tip speed, grinding media size, process time, process temperature and system composition will be discussed. In any case high load conditions, i.e. high stress energies are needed to initiate breakage of polymer materials. Optimization of the process with respect to process time and energy consumption by appropriate selection of process temperature and solvent will be addressed. The selection of appropriate solvents allows for remarkable reduction of mass-specific comminution energy needed.

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Section: Wet Grinding Of Pbtmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Production of PBT/PC particle systems by wet grinding

Schmidt¹,

Romeis²,

Peukert³

2017

AIP Conference Proceedings

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“…Goswami and Singh (2003) used an attrition mill for cumin seed grinding with varying temperature and feed rates. They found higher feed rate with ambient temperature resulted in temperature rise, coarser particles (105.9-158.2 μm) and lower specific energy consumption while finer particle size obtained with low temperature that is, −40 C. Wilczek, Bertling, and Hintemann (2004) experimented with viscoelastic and plastic materials to improve grinding efficiency by making the material more brittle with the use of LN 2. Other grinding parameters viz., feed rates and product temperatures were studied by Murthy and Bhattacharya (2008) in black pepper by employing cryogenic pin mill.…”

Section: Design Parameters Of Cryogenic Grindermentioning

confidence: 99%

Cryogenic grinding for better aroma retention and improved quality of Indian spices and herbs: A review

Saxena

Barnwal

Balasubramanian

et al. 2018

J Food Process Engineering

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Spices are very well‐known for their characteristic aroma and peculiar taste from ancient time. Grinding of spices is an old practice using different grinding equipment suited as per prevailing conditions. In modern era, the popularity of quality processed products has increased in spices. Cryogenics has very important role to play in food sector. Liquid nitrogen is the preferred among all available cryogens to obtain desired low temperature in food grinding. Grinding of spices at very low temperature produced superior quality ground powder with better hygiene. In spite of a proven technology it is not being popular in developing countries including India due to high initial investment. Present review article brings together the original work done to realize physico‐mechanical, thermal and grinding characteristics, aroma profile, and medicinally important compounds of selected spices for developing design of low cost cryo‐grinder specifically for spices and its possible commercial application. Practical applications Cryogenic grinding of spices and herbs not only retain the volatiles with no loss as well as maintain the originality in flavor quality, thus has prospective commercial uses. Enhancement of pharmacological properties opens another important avenue for utilization of this technology for herbal grinding in Ayurveda and other traditional system of medicine. Particle size up to 50 μm may be achieved by cryogenic grinding which in turn will be more effective in medicinal or therapeutic use. Less quantity of herbal drugs will be required if ground cryogenically.

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“…Because traditional grinding is not suitable for PCB recovery, a wet impact crusher and shear hammer mills are generally used to obtain coarse size reduction and liberation of materials [10,20]. To develop a low-cost recycling process for treating PCBs from scrap electronics, selective grinding for ductile and stiff materials was investigated with a PC-assisted impact grinding system that can automatically control various operating conditions in real time [21,22].…”

Section: Introductionmentioning

confidence: 99%