Mixing part 2

Industrial pharmacy I
Lec 2:
mixing
Pharmacist
Hussein kadhim alkufi
MSc in pharmaceutics
Collage of thi-qar
University of pharmacy

Mixer selection
Factors that must be taken into consideration
1_ the physical properties of the liquid material to
be mixed, such as density, viscosity, miscibility.
2_ economic consideration regarding processing
like time required for mixing and the power supply
3_ cost of equipment and it is maintance.

For the liquid material and depending on their
physical properties where different systems:
1_ monophase system
2_ polyphase system

Monophase system
The most important consider are viscosity and density
of the fluids to be mixed determine to a large extent
the type of flow and then the nature of mixing
mechanism involved.
For relative low viscosity fluid (not more than 10
poise)
This type need mixers with high degree of turbulence
with circulate the entire mass of material. This
obtained by air jet, fluid jet, various high speed
impellers

For high viscous liquid (cream, ointment, paste) are
of such highly viscosity not turbulence
and need turbine of flat blade design is more
desired

Polyphase system
This system found in dispersion system in which we
have several liquid, or several solid phase, or solid
with liquid.
This mixture involve (subdivision of the particles)
aggregates of one or more phase to get dispersion of
these particles.

Polyphase system
In liquid dosage form we have subdivision of the
particles or distribution of particles with each other,
so we can get particles ((globules))
For emulsion also we have steps for the reduction of
globules but need high sharing action for mixing, this
can be obtained by use of mechanical stirrer,
homogenizer, colloid mill to get stable emulsion.

Polyphase system
Note: in these system we have different forces:
1_ interfacial tension of the globules in the
surrounding liquid, these forces resist the reduction of
globules size
2_ force of share with the fluid mass generated by
certain devices, tools. The forces may enhance the
division or reduction of globules.
So both of these forces determine the globules size
determination.

Polyphase system
For these system the selection of mixer depending on
different factors related to these systems.
The most important factor is the viscosity
Explain the effect of viscosity on the selsction of mixer
in polyphase system??????????

Polyphase system
Other type of polyphase system we have solid in
liquid mixing.
Have the selection of mixing depend on stage of
manufacture as example for susp.
At first we have mixing for solid particles with low
viscosity liquid, need high speed turbine by which we
can get mixing and reduction for the particle size.

Polyphase system
If no aggregate formed of particle: this system
consider monophase system
If there is aggregation of particles: due to
increase percent of solids, this will give more
highly viscous fluid, more consistency. So paste
is formed and certain type of mixer must be
used for paste mixing like segma plate mixer or
roller miller.

Polyphase system
Other example on Polyphase system can be obtained :
when we have solid particle need to be coated with
liquid coated material(used for specific condition of
mixer) to get homogenous
In this process the liquid add slowly? To avoid the
aggregation of particle.
If sticking occur during coating process due to surface
tension of liquid we need equipment similar to that
used in paste.

Polyphase system
If there is no sticking occur we have particles
have free flow properties, here we need
equipment similar to that use in solid mixing.
The mixer selection depend on particle size or
density

Mixing part 2

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Mixing part 2