(160q) An Experimental Investigation into the Effect of Moisture Content of Salt on Its Flow Properties

The effect of moisture content of granular on its flow properties varies very much from one solid to another. Some solids may increase their moisture content without major change in flow properties, whereas for other solids, even a small increase in moisture content may significantly affect the flow properties. This paper presents the results of an experimental investigation into the effect of variation of moisture content of industrial salt on its flow properties.

It is known that slip-stick might occur in internal friction as well as in wall friction for some solids. In the present tests slip-stick in internal friction was observed during the measurement for the flow properties of this salt with the Jenike shear tester. Such measurements were carried out with samples of different levels of moisture content under different normal stresses. Measurement results showed that slip stick occurred when the moisture content was high, but disappeared when the sample used was dried up, i.e., the moisture content decreases to a certain level. No slip-stick was observed during measurement for the wall friction with stainless steel, no matter whether moisture content of the samples was great or low. The level of normal stress applied during the measurements had little effects on the slip-stick.

Referring to slip-stick of the wall friction, it has been successfully employed to explain the mechanism of some phenomena such as honking occurred in some tall silos. It is recommended that the maximum value of wall friction be taken as the friction angle in silo design for mass flow to occur should slip-stick was observed. The fact that slip-stick of the internal friction is related to the moisture content of solids might have implications to understand the mechanism of solid flow patterns in some industrial operating processes, and in specific the determination of critical parameters in silo design for this salt is to be discussed in the paper.