Introduction
Most of the industries involve the process of mixing, which is considered as one of the most important processes, involving the mixing of solids, liquids, or gases having two or more than two components.
mixing dry powder is through to be an important process in the field of pharmacy because at different steps it might affect the preparation’s efficiency.
Introduction
Such a mixer should be used which facilitates random mixing, and also prevents the conditions which may result in segregation. Thus, the operational conditions should be critically optimized.
Mixing Equipment-Criteria
1) The equipment should not be filling machines for more than 60% to leave sufficient mixing volume, because the powder bed expands.
2) The particles should be mixing technologies in three directions.
3) The resultant shearing force should prevent aggregation.
4) The selected mixing mechanism should be appropriate and should be continued for a desired time.
5) Centrifugal effect should not arise to prevent the separation of powder according to their weights.
6) The particles should not breakdown under the influence of forces to prevent demixing which may occur due to particle size differences.
7) Mixing should be abruptly stopped, because demixing may occur due to unidirectional slow or diminishing forces. Therefore, after mixing the powder blend butterfly valve.
Some of the mixers discussed below are:
1) Double Cone Blender
Double cone blender is a competent and versatile machine used for enables uniform mixing blending of granules and dry powders. It is made up of stainless steel. It is available in a wide range of working capacities ranging from 5 – 500 liters.
Principle
Double cone blender produce a homogeneous solid-solid mixture. This equipment involves axial mixing as the powder moves In different sections. This blender provides through mixing depending on its speed of rotation.
Construction
The body of double cone blender consist of two cone-shaped sections. These are joined to a central cylindrical uniform mixing and easy section at their bases. The rotational axis is perpendicular to the cone axis and passed through the cylindrical section. The blender body is held by two lateral supports. One of these supports is fitted with the driving motor.
Working
The autoclaved double cone blender’s angle is adjusted with the help of a moving wheel so that the material can be conveniently loaded. After loading, the lid of the blender is closed, and the lid is secured by fitting the safety pin within its groove. Then the safety guard is put and the equipment is switched on. After the blending process is complete, the safety guard is removed (only after switching the equipment off), the blender is adjusted to an angle (so that the material can be conveniently unloaded), the safety pin is unlocked, and the lid is opened.
Uses
Double cone blender has the following uses:
1) It is employed in different industrial mixers industries for the preparation of different products such as pharmaceutical, food, chemical, cosmetic products, etc.
2) It is used for uniform mixing of granules or dry powders.
3) It is used for the preparation of pharmaceuticals, food, and chemical products.
4) It is used for providing heating and cooling effect with the help of jacketed construction.
Merits
Double cone blender has the following merits:
1) Large quantity of material can be easily handled.
2) It requires minimum maintenance cost.
3) It can be easily cleaned and maintained.
4) It can be easily operated with easy charging and mixing and easy discharge of the material.
Demerits
Double cone blender has the following demerits:
1) It requires large headspace for installation.
2) Due to insufficient sharing force, it is not suitable for materials having large differences in particle size distribution or for system containing fine particles.
2 ) V – Cone Blender
Twin shell blender is a popular tumble blender commonly used in the pharmaceutical and food industries. it is available in a wide range of working capacities ranging from 5-500 litres.
Principle
Twin shell blender works on the principle of diffusion involving small scale random movement of solid particles. The high shear mixers movement of blender increase the mobility of each particle, thus promoting diffusive blending.
When the particles are spread over a freshly developed interface, diffusion blending occurs. The diffusive blending will lead to a high degree of homogeneity if segregation does not occur. Thus, twin shell blender is preferred for obtaining precise blend formulations.
construction
Twin shell blender consists of two cylindrical vessels located at such an angle that it forms a “V” shaped structure (thus also named as v-cone blender). This shape provides a non-symmetrical form about the rotational axis, providing efficient mixing paddle mixers.
Working
Twin shell blender consists of two hollow cylindrical shells joined at 75-90 angles. Container of the blender is supported on trunnions so that it easily tumbles. The material within the container splits and recombines as it tumbles, thus promoting mixing as the material freely and randomly falls inside the container. A homogenous blend is obtained due to repetitive converging and diverging movements of material along with increased frictional contact parts between the material and the container walls.
Uses
Twin shell blender has the following uses:
1) It effectively mixes the freely flowing dry powders and granules homogeneously.
2) It is used for free-flowing, non-segregating powders.
3) It is also used for wet blending.
4) It is used to gently mix the friable solid material.
5) It is also used to mix powders of varying densities.
Merits
Twin shell blender has the following merits:
1) It can be easily cleaned and maintained.
2) Large quantity of material can be handled easily.
3) It requires minimum maintenance cost.
4) it can be used for fragile materials as it does not have blades due to which particle size reduction and attrition occurs.
5) It facilitates easy loading and unloading of materials.
6) Its conical shape allows complete discharge of the product without any wastage.
7) It does not have a shaft mixer projection; thus, product contamination does not occur.
Demerits
Twin shell blender has the following demerits:
1) It requires large headspace for installation.
2) Due to insufficient shearing force, it is not suitable for materials having large difference in particle size distribution or for system containing fine particles.
for more pharmacy notes :
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