Effect of grinding aids on the time-flow characteristics of the ground product from a batch ball mill
| Autor: | P.B. Rajendran Nair, R. Paramasivam |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
Materials science
General Chemical Engineering Extrapolation Mineralogy Grinding (comminution) flow characteristics powder Blank Tensile strength Density (specific gravity) shear rate Ultimate tensile strength Mill Internal friction Ball mills Composite material Yield stress Ball mill Mathematical models Calcium stearate calcium conformational transition Calcite solid flow Additives Mechanical testing stearic acid particle size Shearing cohesion Shear tests Grinding Flow of solids Compressibility of solids Particle-size distribution Compressibility Jenike flow factor testers flow rate Direct shear test Flowability index Batch ball mills |
| Zdroj: | Powder Technology. 101:31-42 |
| ISSN: | 0032-5910 |
| DOI: | 10.1016/s0032-5910(98)00121-1 |
| Popis: | To explore the probable mechanism for enhancement of breakage rate of particles brought about by additives during fine grinding in media mills, the flow characteristics of the ground product were estimated using the Jenike flow factor tester for blank, additive and additive delayed samples, ground to various grinding intervals up to 30 min duration. It was found from shear tests results that the presence of calcium stearate as an additive in the mill material charge during fine grinding of calcite in a batch ball mill had increased its bulk density and major consolidation pressure, while reducing the compressibility, internal friction factor, effective angle of friction, unconfined yield strength, shearing cohesion, extrapolated tensile strength and flowability index. All these changes were more significant during the finer stages of grinding and, from the point of bulk solids flow, they are all flow favourable variations. The flow parameters were characterised by relating them to major consolidation pressure with appropriate equations and it was found that for the blank sample most of the parameters can be fitted with long-hand type equations, while for the parameters of the additive sample exponential equations were found to be the best fit.To explore the probable mechanism for enhancement of breakage rate of particles brought about by additives during fine grinding in media mills, the flow characteristics of the ground product were estimated using the Jenike flow factor tester for blank, additive and additive delayed samples, ground to various grinding intervals up to 30 min duration. It was found from shear tests results that the presence of calcium stearate as an additive in the mill material charge during fine grinding of calcite in a batch ball mill had increased its bulk density and major consolidation pressure, while reducing the compressibility, internal friction factor, effective angle of friction, unconfined yield strength, shearing cohesion, extrapolated tensile strength and flowability index. All these changes were more significant during the finer stages of grinding and, from the point of bulk solids flow, they are all flow favourable variations. The flow parameters were characterized by relating them to major consolidation pressure with appropriate equations and it was found that for the blank sample most of the parameters can be fitted with long-hand type equations, while for the parameters of the additive sample exponential equations were found to be the best fit. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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