Z-blade mixer

For the batch mixing of viscous pastes and doughs using ribbon impellers and Z-blade mixers, the tanks may be mounted horizontally. In such units, the working volume of pastes and doughs is often relatively small, and the mixing blades are massive in construction. 

Z-blade mixers Shearing and kneading by the specially shaped blades Mixing heavy pastes, creams and doughs Bakery industry, mbber doughs, plastic dispersions... 

A vertically arranged rotor system consisting of protruding arms revolves within a cylindrical chamber fitted with stationary deflector protrusions. The combination of the movable rotor and static protrusions effectively mix the diced rubber feed and solvent by turbulent flow. It is usual to have at least three speed possibilities and thus lump-free preparation of the product is possible in relatively short mixing times. Mixing times for these machines is considerably less than for the Z-blade mixer. 

Pretzels are made from a very stiff dough that is made from a low protein soft wheat flour, e.g. one made from a soft white winter wheat. The water level would be only 38 42%, with 0.25% yeast and 1% shortening, 1 % salt and 1 % dry malt. The dough would be mixed in a Z blade mixer and then left to prove for up to 4 hours. 

Ellis, S.P., Gray, K.R. and Biddlestone, A.J., Mixing evaluation of a Z-blade mixer developed as a novel solid state bioreactor. Food Bioprod. Proc., 72 (1994) 158-162. 

Preparation of Plastisol. In all cases the plastisols were prepared on a Wink-worth-Z blade mixer and degassed before use at less than 0.1 mm. of Hg. The same order of mixing and similar mixing and degassing times were employed. A liquid cadmium-barium stabilizer was used. 

Low-Shear Granulators. These are the traditional granulators and are of the planetary type (e.g., Hobart, Collette) or the kneading type (Z-blade mixers). Another type of these low-shear granulators consists of a V-blender with an intensifier bar (e.g., Patterson-Kelley). 

The Z-blade mixer is another twin trough mixer and is commonly used for pastes as well as powders (Figure 3.4). The polished Z-blades make this one of the easier convective mixers to clean between operations. 

Figure 3.4 Winkworth Z-blade mixer (courtesy Winkworth Machinery)...

Ashton and Valentin compared the performance of an Airmix, Nautamix, Oblicone and Z-biade mixer using equi-sized particles of sand and calcite. The mixture quality achieved approached that of the random mixture quality in all four mixers but this condition was achieved most rapidly in the Airmix followed by the Oblicone, Nauta and Z-blade mixers. When testing the effect of mixer variables on the quality of mixing achieved it was found that the tumbler mixer permance was very dependent on rotational speed. 

Initial shredding or granulation of the rubber aids dissolving. Alternatively, lightly mill the rubber and zinc oxide, then add solvent. Blend the swollen mixture in a Z-blade mixer until homogeneous, then add ester gum, antioxidant, and finally, lanolin. 

BMC is manufactured by feeding the paste premix into a Z-blade mixer, where chopped glass fiber is added and mixed in until it is thoroughly distributed (Figure 4.5). The resulting dough is either... 

Compression moulding (hot press moulding) Moulding compounds (often complex mixtures, e.g. dough or bulk moulding compounds) prepared in Z-blade mixer and heated under pressure in closed mould Small to medium articles, especially electrical mouldings large capital outlay... 

Z-blade mixers are used for a variety of dough-like mixes, and liquid dispersions. Other means for discharge include tipping the mixer about its horizontal axis, and bottom doors which dump the mix through the bottom of the mixing chamber. The screw discharge used by Lucas is particularly suitable for DMC. 

A process associating a batch kneading step, typically in a Z-blade mixer to an extruding step in a screw extruder... 

Low viscosity pastes ean usually be manufactured using simple stirrers to disperse and/or dissolve the raw materials. However, as the viscosity increases so does the need to use high-shear stirrers sueh as toothed-bladed stirrers, planetary mixers and/or Z-blade mixers. 

Three types of mixers are particularly used (see Figure 5.32) Z-blade mixers, roller mixers (in which the mixture is forced between two heating rollers, with variable spacing and turning at different speeds) and double screw mixers, mainly used in extrusion techniques. 

Figure 5.32. The main types of mixers A) Z-blade mixer, B) roller mixer, C) double screw mixer...

Double blade mixers such as the Z blade mixer shown In Figure Z, have been used for the preparation of wax based injection moulding mlxtures but have the disadvantage that the material can find dead spaces 1n the vessel. The greatest success has therefore been achieved with double cam type mixers twin roll and twin screw extruders ... 

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