Mixing kneading paddles

Figure 16-35 Expansion/compression mixing cycle in kneading paddles.

Pan mixers Vertical, rotating paddles, often with planetary motion Mixing, whipping and kneading of materials ranging from low viscosity pastes to stiff doughs Food, pharmaceuticals and chemicals, printing inks and ceramics... 

The reaction of solid fluorspar with liquid sulfuric acid produces a solid (calcium sulfate) and a gaseous (hydrogen fluoride) product. The reaction passes through a paste-like phase. Many reactor modifications have been developed to attain an optimal reaction in this phase. The aim is thorough mixing of this phase, which is achieved by internal fittings in the rotary tube (e.g. paddles) or by kneading the reaction mixture in a kneader. 

The paddle mixer can also be used for kneading and for mixing pastes since the kneading action allows phase changes from dry to paste when liquid is added. To evaluate the suitability of such mixers, it is recommended that test trials are conducted on the mixture to judge the duration and the quality of mixing. Paddle mixers are so versatile, they are also used as dryers and coolers for bulk solids. 

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