Skip to main content

Renin Angiotensin Mechanism.

Ball Mill.

 Ball Mill.

Principle: 

  • Works on the principle of Impact and Attrition.

Diagram:

Construction:

  • The mill consists of a hollow cylinder fixed on a metallic frame in such a way that it can rotate around its horizontal axis.

  • The cylinder contains metallic balls occupying around 30 to 50% of total capacity.

  • The balls are usually made up of rubber, porcelain or metal.

  • The metallic balls are coated with chrome.

  • The weight of balls is kept constant and size of balls depends upon the size of feed and mill.

Working:

speed of ball mill

  • The material to be reduced in size is entered into the machine through a hopper.

  • The electrical supply to the machine is started after a careful closure of the machine feed.

  • The mill is rotated at optimum speed.

  • For effective size reduction, the speed of the machine plays a very important role.

  • If the machine is rotated at low speed the balls collide with each other and no or negligible size reduction takes place.

  • If the machine is rotated at very high speed the balls rotate along the cylinder wall due to centrifugal force and no size reduction takes place.

  • If the machine is moved at an optimum speed (two third speed)

  • Size reduction takes place as balls move at the top and fall down crushing the material by impact and attrition.

  • After sufficient time the mill is stopped and the product is collected.

Advantages:

  1. One of the most efficient mills can produce very fine powders.

  2. Suitable for both wet and dry grinding.

  3. As operation takes place in a closed environment, the mill is useful for potent materials.

  4. The mill, after some modifications, is useful for continuous operation.

Disadvantages:

  1. Not suitable for sticky products.

  2. Very noisy.

  3. Balls and casing material may wear off and can compromise the purity of the product.

Applications:

  • Useful for a variety of materials to produce fine powders.

Commonly Asked Questions.

  1. What is size reduction. Write Principle, Construction and working of Ball Mill.

  2. Write a note on Operation speed for Ball Mill.
Labels:

Popular posts from this blog

Heat Exchangers and Heat Interchangers.

  In pharmaceutical industries many types of equipments are used for transfer of heat, they can be classified as follows, Heat Exchangers. Heat Interchangers. Heat Exchangers: These devices are used for transferring heat from a fluid (Hot Gas or Steam) to another fluid (Liquid) through a metal wall. Heat Interchangers: These devices are used for transferring heat from a One liquid to another liquid or one gas to another gas through a metal wall. HEAT EXCHANGERS; The equipment used for heat transferring are known as heat exchangers. Some of the processes that involves heat transfer in pharmaceutical industries are: Preparation of starch paste (in steam jacketed kettle). Crystallization. Evaporation. Distillation.  Classification of heat exchangers On the basis of transfer of heat, heat exchangers are classified as: Direct transfer type:  The hot and cold fluids are separated by a metal wall through which the heat is transferred from hot fluid to cold fluid. E.g. shell and ...
Read more

Rate of Drying Curve.

  Definition Drying is defined as the removal of liquid from a product usually with application of heat. Rate of Drying Curve. Drying process can be divided into three periods Initial Adjustment Period. Constant drying rate period. First falling drying rate period. Second falling rate period. Initial Adjustment Period (A-B): Also called the “ Heating up” period . In this period the substance gets heat and increases in temperature. Drying has not yet started. Constant drying rate period (B-C): During this period the temperature of the solid and the rate of drying remain constant. The moisture evaporating from the surface is replaced by water diffusing from the interior of the solid at a rate equal t o the rate of evaporation.  The moisture content at the end of constant rate (point C) is referred to as the critical moisture content (CMC).  At CMC, dry spots start appearing and drying rate starts falling . First falling drying rate period (C-D): This period is also called ...
Read more

Glycogenesis.

  Definition: Biosynthesis of Glycogen from Glucose is called Glycogenesis. Glycogen is synthesized  Depending on the demand for glucose and ATP (energy), insulin promotes the glucose conversion into glycogen. Glycogen is the major storage form of carbohydrate in animals similar to starch in plants. It is a homopolymer made up of repeated units of α- D glucose and each molecule is linked to another by 1→4 glycosidic bonds . Once there is a chain consisting of 8 to 10 glycosidic residues in the glycogen fragment, branching begins by 1→6 linkages . Glycogen is stored in liver and skeletal muscles. Location: Cytoplasm of cells in the muscle, liver, and adipose tissue. Steps Involved in Glycogenesis: Glucose is converted into glucose-6-phosphate by the action of glucokinase or hexokinase  with conversion of ATP to ADP. Glucose-6-phosphate is converted into glucose-1-phosphate by the action of phosphoglucomutase. Glucose-1-phosphate is converted into UDP-glucose by the actio...
Read more