Sedigraph procedures

Particle size distribution and classifier selectivity have been determined, using kernel density estimations, to data from (two) classifier flow streams. The procedure has been applied to hydrocyclones using platey particles whose sizes were determined with a Sedigraph 5100 and spheroidal particles whose size distributions were determine using the Malvern Mastersizer and the Coulter Counter [8] Svarovsky s equation was used [9,10]. 

Many industries have large data banks on product size distributions by sieve analysis and want to continue using this form of presentation. In order to accommodate this need Cho et. al. [48] converted Sedigraph data to sieve data using wet screened powder in the 38 to 53 pm size range and fitted the data to a logarithmic distribution to give the slope and median size. This procedure must be use with caution since the conversion factors are shape dependent and a new calibration is required for each product. 

When comparing results with other methods it is often necessary to dilute the suspensions without changing their state of agglomeration. Despite this, under electrokinetically stable conditions, excellent agreement was found in a comparison with the Mastersizer S, the Ultra Fine Particle Analyzer, the Sedigraph 5000D and scanning electron microscopy [265]. It was stressed however that sample preparation procedure was important. 

Mica products are usually analyzed by screening to determine particle distributions. Specifications typically include minimum and maximum values for the amount of mica passing or retained on screens of varying mesh sizes. Another value often used for a material specification is loose bulk density. Laser particle size analysis is also being used to some extent to define mica products. One should remember that most other minerals are measured by an instrument called a sedigraph, which measures the size of particles based on their settling rate. This procedure can be used with very small low-aspect ratio minerals such as calcium carbonate, talc, silica, very small particle size mica, and aluminum trihydrate but cannot be used for analysis of most mica products. Sedigraph particle size values for very small mica products are about one-half to one-third of the values obtained by laser diffraction. 

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