Fundamental powder mixing mechanisms Export

@article{bridgwater76, abstract = {Traditional methods of seeking to understand powder mixing are evaluated and it is found that few fundamentals generalisations have emerged. This is ascribed to a reluctance to come to terms with and understand the unique properties of powders. This reluctance stems from difficulty in performing reliable experiments free of sampling uncertainties and the inability to understand the influence of sample size on sample concentration. The limitations that have been found in more fundamental studies on equipment are outlined. It is pointed out that powder behaviour depends on whether the powder can be considered cohesive or cohesionless. Cohesionless powders do not form agglomerates capable of withstanding tension, and are particularly susceptible to bulk and free surface segregation. Also, the evaluation of mixing depends on the process requirement: a duty may be macroscopic, demanding, say, compatible residence time distributions of the components, or may be microscopic, demanding satisfactory detailed distributions. Particular consideration is given to processes occurring in bulk powders; for example, the influence of consolidation, the development and spacing of failure zones, the inherent time and position dependence of powder composition and strength, and segregating effects of individual cohesionless particles or individual cohesive agglomerates. It is proposed that two key length scales may be sufficient to describe a powder mixer, namely the failure zone spacing and the failure zone height. More generally, it is concluded that laboratory tests for mixers are of restricted value and that work in future should concentrate on industrial scale studies and on fundamentals.}, author = {Bridgwater, J.}, citeulike-article-id = {5089217}, citeulike-linkout-0 = {http://dx.doi.org/10.1016/0032-5910(76)80051-4}, citeulike-linkout-1 = {http://linkinghub.elsevier.com/retrieve/pii/0032-5910(76)80051-4}, doi = {10.1016/0032-5910(76)80051-4}, issn = {00325910}, journal = {Powder Technology}, keywords = {drum, granular, segregation}, month = {December}, number = {2}, pages = {215--236}, posted-at = {2009-07-07 19:04:06}, priority = {2}, title = {Fundamental powder mixing mechanisms}, url = {http://dx.doi.org/10.1016/0032-5910(76)80051-4}, volume = {15}, year = {1976} }

TY - JOUR ID - bridgwater76 L3 - citeulike-article-id:5089217 N2 - Traditional methods of seeking to understand powder mixing are evaluated and it is found that few fundamentals generalisations have emerged. This is ascribed to a reluctance to come to terms with and understand the unique properties of powders. This reluctance stems from difficulty in performing reliable experiments free of sampling uncertainties and the inability to understand the influence of sample size on sample concentration. The limitations that have been found in more fundamental studies on equipment are outlined. It is pointed out that powder behaviour depends on whether the powder can be considered cohesive or cohesionless. Cohesionless powders do not form agglomerates capable of withstanding tension, and are particularly susceptible to bulk and free surface segregation. Also, the evaluation of mixing depends on the process requirement: a duty may be macroscopic, demanding, say, compatible residence time distributions of the components, or may be microscopic, demanding satisfactory detailed distributions. Particular consideration is given to processes occurring in bulk powders; for example, the influence of consolidation, the development and spacing of failure zones, the inherent time and position dependence of powder composition and strength, and segregating effects of individual cohesionless particles or individual cohesive agglomerates. It is proposed that two key length scales may be sufficient to describe a powder mixer, namely the failure zone spacing and the failure zone height. More generally, it is concluded that laboratory tests for mixers are of restricted value and that work in future should concentrate on industrial scale studies and on fundamentals. IS - 2 JF - Powder Technology SN - 00325910 EP - 236 TI - Fundamental powder mixing mechanisms VL - 15 SP - 215 KW - drum KW - granular KW - segregation AU - Bridgwater, J PY - 1976/12// UR - http://dx.doi.org/10.1016/0032-5910(76)80051-4 ER -