Determination of Cerchar Abrasivity Index of rocks скачать в хорошем качестве

Determination of Cerchar Abrasivity Index of rocks

Determination of Cerchar Abrasivity Index of rocks Scope: The CERCHAR Abrasivity Test is intended as an index test for classifying the abrasivity of a rock material. Apparatus: 1. Stylus: It is strongly recommended to employ only styli tempered to Rockwell hardness HRC 55 ± 1. The diameter of the stylus should be at least 6 mm. The tip of a stylus shall have a conical angle of 90°. A worn stylus should be re-sharpened and the tip angle checked under a microscope before use in a further test. 2. Force: The static force acting on the stylus should be 70 N. 3. Grinder: Each used stylus should be re-sharpened using a standard abrasive stone wheel. 4. Test Specimen: The rock sample may be either disc-shaped or irregular in shape. The size of the rock surface should be sufficient to permit five test scratches that are at least 5 mm from the edge of the rock surface. Each test should be 5 mm apart. Test Procedure: 1. The sample should be clamped firmly in the vice while observing the desired scratching direction. 2. The rock surface should be, to the extent possible, horizontal. 3. The stylus should be carefully lowered onto the rock surface to avoid any damage to the tip of the stylus. 4. The stylus should be positioned so it is vertical and perpendicular to the rock surface. 5. The length of a test scratch in the rock sample must be exactly 10.0 mm within 1 s. 6. During the test there should be constant contact between the stylus and the rock surface. 7. After testing, the stylus is carefully lifted from the rock surface and the stylus removed. 8. A minimum of five test replications must be made on the rock surface, each time by a new or re-sharpened stylus. Instructor: Dr. Radhakanta Koner, Department of Mining Engineering, IIT(ISM) Dhanbad Students: MTech students of Mining Engineering, IIT(ISM) Dhanbad Course Name: Geomechanics Practical (MNC505) Session: 2020-21, Monsoon Acknowledgment Prabhat Kumar Mandal Krishna Murari Birju Gope Vijay Karanga