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      Ball Mill Inspection Procedure (preparation)    
               
      1. Introduction      
      - This document is intended to help the staff of the cement plants.    
      - On a process point of view, a mill inspection is only representative if the grinding mill circuit is in a steady  
        working condition with a representative cement product.    
      - If this condition is fulfilled, the whole installation must be stopped in crash-stop    
      - It means all the equipments must be stopped at the same moment, especially weighfeeders, fresh material
        belt conveyor and separator rejects devices if closed circuit.    
      - If one of the hereabove mentioned points is not respected, the first chamber will probably have a lot of undesired material.
      - Before to work around the ball mill, all the safety procedures must be done and checked by the staff   
        concerned by the visit of the mill.      
      - It is also better to leave a small ventilation in order to cool both mill's chambers.    
      - Flap of the fan must be opened around 10-15%.      
      - It is better to enter first into the first compartment in order to follow the flowpath of the material from the beginning
        of the grinding process.      
      - Generally, people enter by the manholes foreseen for both compartments    
      - From time to time, when the mill diameter is larger, it is possible to enter by the inlet trunnion in the first  
        chamber and by the central screen of the intermediate diaphragm in the second chamber.  
      - This procedure was performed for a 2 compartments mill.     
      - For other configurations of mills, a simple adjustment is necessary.    
      - For outside staff, it is also necessary to check the kind of internals and the length of the chambers.
               
      2. Essential accessories      
      - In order to carry out the right visit, some accessories are required.    
      - A list of items below.      
      - The light:      
        * A torch is the minimum required but not sufficient the most of the time:    
       
     
         
             
             
             
             
             
             
             
        * As some people can take measurements, pictures or write, it is better to install a worksite light in order to
        illuminate the whole compartment:      
       
     
         
             
             
             
             
             
             
             
        * Or better:      
       
     
         
             
             
             
             
             
             
             
      - A waterproof camera is required in order to avoid premature wear and possible damages due to the dust:  
       
     
         
             
             
             
             
             
             
             
      - A measuring tape:      
       
     
         
             
             
             
             
             
             
             
      - A small pocket notebook:      
       
     
         
               
               
               
               
               
               
     
      -
    A pencil because a ballpoint pen will not work well due to the high temperature:
         
       
     
         
             
             
             
             
             
             
             
      - Bags for the first chamber samples, big enough and resistant for 5 kg:     
       
     
         
             
             
             
             
             
             
             
      - It is better to mark the sample number on the bag before to go inside the mill.    
      - A scoop to take the samples:      
       
     
         
             
             
             
             
             
             
             
      - This scoop will be used for first chamber sampling and first part of second chamber sampling.  
      - Bags for the second chamber samples, big enough for 2-3 kg and heat resistant (up to 150°C in some cases):   
       
     
         
             
             
             
             
             
             
             
      - As for the 1st chamber, it is better to mark the sample number on the bag before to go inside the mill.  
      - A coarse sieve of 12-15mm aperture (depending of the smallest balls dimension) to avoid the balls to go  
        in the sample.      
      - This sieve will be used in the second chamber and in the small balls area.    
       
     
         
             
             
             
             
             
             
             
      - A shovel to take the sample with a mixture of balls and cement:    
       
     
         
             
             
             
             
             
             
             
      - An empty cement bag or similar to place under the coarse sieve and to recuperate the cement sample:  
       
     
         
             
             
             
             
             
             
             
      3. Inspection of the mill      
      - It is useful to remember that the port of appropriate clothing, safety boots, protective glasses and mask are
        normally mandatory.      
      - After the crashstop, between two and four hours are normally necessary to decrease the temperature  
        of the mill and allow an inspection with a minimum of comfort.    
      - However, the temperature can be even high.      
      - So, let's go inside the mill (for the sauna...):      
       
     
         
             
             
             
             
             
             
             
             
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    All rights reserved © 2012-2016 The Cement Grinding Office