Blade Mixers with Horizontal Shafts: Operating Principle
The mixer is intended for mixing finely divided clay material with various additives. For mixing clay during semi-dry and soft molding of ceramic products, as well as for making charge in glass, silicate and other industries, single-shaft and twin-shaft blade mixers with continuous and cyclic operation are widely used.
Mixers of this group are used both for making charge of several components, and for making a homogeneous dry or moistened mass. Moistening can be carried out with water or low pressure steam.
In the latter case, we get a higher quality product, as steam heats the mass and then condenses and moistens it. The main parameter of blade mixers is their output. The market offers blade mixers for sale with the following output (as for clay): 3, 5, 7, 18 and 35 m3/h, respectively with blades diameter of 350, 600 and 750 mm.
A continuous twin-shaft blade mixer consists of a trough-shaped body closed with a cover containing horizontal shafts fitted with blades. The shafts are driven towards each other by an engine through a friction clutch, a gearbox and a gear pair.
The blades are installed at angles, at which an optimal ratio of circumferential and axial particles moving speed is achieved, thereby providing the necessary travel time of components from the window to the discharge gate and, consequently, mixing quality.
For moistening the mixture, steam is supplied through the gaps in the scaly bottom; steam is fed by a pipe through distributing valves. To reduce heat loss, the lower part of the housing is closed by a casing filled with mineral wool. The mass can also be moisturized by water supplied through a manifold.
To ensure high-quality mixing, twin-shaft counterflow mixers are used. Their design is identical to design of the mixer shown above, but the angles of the blades installed on the shafts are opposite in sign. Such blades installation scheme creates certain particles counter flows with the general direction of mixture movement towards a discharge window, because angular speed of the shaft is bigger than angular speed of the shaft.
Blades installation angles and the ratio of the shafts angular speeds for specific conditions are defined by practice. To pre-mix dry mixes, single-shaft blade mixers are used. Most often, they perform two functions: they mix and transfer materials, for example, from silos to other units. Design of such mixers is similar to design of those discussed above, but they have one blade shaft.
For particularly thorough mixing (of difficultly homogenizing mixtures) cyclic action mixers are used, for example, twin-shaft mixers with Z-shaped blades. Depending on the desired homogeneity, mixing duration in such mixers can be 20-30 min.
Twin-shaft continuous blade mixers can operate in a cyclic mode as well, if we fit them with a shutter and change the blades installation scheme.
Strommashina Samara Plant manufactures mixing equipment, as well as other industrial equipment featuring high reliability and performance. Own production facilities, highly qualified employees and extensive experience allows Strommashina designing and supplying highly competitive machines for businesses worldwide.