Experimental study by online measurement of the precipitation of nickel hydroxide: Effects of operating conditions

The objective of this work is using the online measurement method to study the process of precipitation of nickel hydroxide in a single-feed semi-batch stirred reactor with an internal diameter of D = 240 mm. The effects of impeller speed, impeller type, impeller diameter and feed location on the mean particle size d43 and particle size distribution (PSD) were investigated. d43 and PSD were measured online using a Malvern Insitec Liquid Process Sizer every 20 s. It was found that d43 varied between 13 μm and 26 μm under different operating conditions, and it decreased with increasing impeller diameter. When feeding at the off-bottom distance of D/2 under lower impeller speeds, d43 was significantly smaller than that at D/3. PSDs were slightly influenced by operating conditions.

The effect of stirrer speeds on main particle size (d43) and particle size distribution (PSD) was measured online. d43 decreases with the increase of stirred speed, which means that the higher the impeller speed, the smaller the particle size. At a low stirrer speed (300 r·min− 1), the resulting PSD is comparatively broader compared to the PSDs at 400 r·min− 1 and 500 r·min− 1. And the peak values also increase with the impeller speed. It was mainly because higher stirring speed results in better micromixing, which favors nucleation and thus narrower PSDs are obtained.Figure optionsDownload as PowerPoint slide