Ball Mill

made by Rafi ullah student of Chemical engineering in PU lahore

1. PRESENTATION: PREPARED BY: RAFI ULLAH M13-CE54

2. BALL MILL

3. TABLE OF CONTENT: INTRODUCTION DEFINITION BASIC PRINCIPLE CONSTRUCTION WORKING ADVANTAGES AND DISADVANTAGES APPLICATIONS EQUATIONS

4. BALL MILL INTRODUCTION: It is efficient tool for grinding many materials into fine powder. There are two types of grinding, the dry process and wet process.

5. DEFINITON: A   ball mill  is a type of  grinder  used to grind and blend materials for use in mineral dressing processes, paints, pyrotechnics, ceramics and selective laser sintering etc.

6. PRINCIPLE: A ball mill works on the principle of impact and attrition. size reduction is done by impact as the balls drop from near the top of the shell.

7. CONSTRUCTION: Wet or dry ball mill grinding machine consists of following parts: Feeding part Discharging part Turning and driving part( gear, motor etc ) Rotating balls

8. CONSTRUCTION (CONT): Consist of a hollow cylindrical shell rotating about its axis. The axis of the shell may be horizontal or at some angle. It is partially filled with balls. These balls are grinding materials, made up of chrome steel, stainless steel or rubber. The inner surface of the hollow cylinder is lined with a resistant material such as manganese steel or rubber.

9. CONSTRUCTION (CONTD) The length of mill is approximately equal to its diameter. Ball occupy about 30-50% of the volume. The dia of ball is 12mm to 125mm . The dia of shell is 3m and its length is about 4.25m. The shell is rotated through a drive gear with speed 60-100 rpm .

10. WORKING: The material to be grind is fed at angle of 60 degree into the crushing zone and the product is discharged at 30 degree. As the shell rotates the balls are lifted up on the rising side of the shell and they cascade down from near the top of the shell. The solid particles in between balls are ground and reduced in size by impact.

11. If the rate of feed increased, coarser product will be obtained and if speed of rotation is increased the fineness for a given capacity is increases. During grinding, the balls themselves wear and are continuously replaced by new ones so that mill contains balls of various ages. Ball mill produces 1 to 50 ton/ hr of powder and energy requirement of the ball mill is about 16 kwh/ton.

12. ADVANTAGES OF BALL MILL The cost of installation is low. The cost of production is low. It is suitable for materials of all degree of hardness. The grinding medium is cheap. Suitable for both batch and continuous operations.

13. DISADVANTAGES: Rotational ball loading difficulty Mill efficiency is low The mill feed size range is wide Not easy to get thinner end product

14. APPLICATIONS: Metallic powders Carbon and coal Phosphate rock Gypsum grinding Limestone milling Cement processing Fertilizers Silicate products Dressing production Granite