A new method of testing separators

This section describes a new and simple experimental method for obtaining the reduced cut size and the rest of the reduced grade efficiency curve of an operating separator. The method relies on feeding a known and fiiUy characterized slurry to the separator under test, and on measuring only two solids concentrations (in the feed and in the overflow), one static pressure differential (or some other flow rate-dependent variable) and the slurry temperature. These measurements are best done and logged by a personal computer, and, for hydrocyclones, have to be repeated at two different pressure settings. 

The new method eliminates the need for sampling, particle size determinations (except that of the feed suspension but this is only done once for a whole string of experiments) or flow rate measurements. This makes the tests simpler than the conventional test methods and also capable of being performed by simple, on-line instrumentation and a computer. 

In this section, the underlying theory is fully developed and its application demonstrated on a specific case of testing a small diameter hydrocyclone used for monitoring very fine particle size in industrial slurries.  

Testing the grade efficiencies of separators is a tedious and time-consuming task. It is still very much needed, however, particularly when investigating the effect of feed concentration of solids where, for most separators, the scale-up theory still requires experimentally determined constants. 

The conventional test method (see section 3.3.1) requires sampling of at least two of the material streams involved. This is followed by full particle size analyses (and concentration measurements) of these samples and, also, by flow rate measurements for the necessary determination of the total solids recovery to imderflow. Alternatively, the total solids recovery can be evaluated from the particle size distributions in all three streams around the separator, see section 3.3.1.4. 

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