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      Second chamber    
          Action Data-Measurement Reason
      1   Intermediate diaphragm    
        - Check the condition and the wear of the back Visual and To insure the protection of the diaphragm frame.
          plates thickness  
         
     
       
      2   Volume load or filling degree    
        - The measurement must be achieved in 4 points 4 points To maintain the production (tons/hour) of the mill
          on the mill-axis (inlet, first third of compartment, (mesure height H) because the volume load is directly linked to the
          second third and compartment outlet). The best   mill absorbed power and the mill efficiency.
          procedure is probably to measure the height    
          from the ball charge to the linings    
        - Other method: count the number of visible At least 4 points If it is the only way to measure the volume load.
          lining plates (less reliable method)    
         
     
      Like the first chamber.
      3   Linings    
        - Check the condition and the wear of the linings    To maintain the lining efficiency (don't forget that
                the function of the 2nd chamber is TO GRIND).
        - Check if there are broken plates Number To maintain the mill shell protected.
        - Check if there is coating on the linings Evaluate the impor- This phenomenon can happen, especially in the
            tance of the problem case of open circuit.
            Evaluate if it is hard Causes inefficient grinding, low throughput and
            to remove, measure high energy consumption.
            the thickness  
         
     
       
      4   Ball charge and classification    
        - Check the ball charge: the principle is to evaluate Better with To respect the initial ball charge recommendation.
          visually the proportion of big balls (Ø60mm) and experienced To maintain the efficiency of the 2nd
          small balls (Ø17-15mm) persons compartment.
        - Measure the biggest and the smallest ball Minimum Ø To determine the next ball make up composition
          diameter Maximum Ø or the substitution of the ball charge.
        - Check if there are broken balls Visual estimation To avoid blockage of the outlet diaphragm slots.
              To analyse the balls quality with the supplier.
        - Check if there is coating on the balls Evaluate the impor- Causes inefficient grinding, low throughput and
            tance of the problem high energy consumption.
            Evaluate if it is hard  
            to remove  
        - In case of classifying lining, check the  Visual estimation Bad classification may be due to a bad lining,
          classification of the balls (perfect, good, poor or Sampling of the charge excessive coating or presence of unground
          disturbed, mixture of the balls, reversed but takes time and a  particles coming from the first compartment.
          classification) lot of hard work Causes inefficient grinding, low throughput and
              high energy consumption.
         
     
       
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      5   Material level    
        - Check the material level (too high you don't see Visual estimation Not enough material may be due to high air velocity.
          the balls, good if you see the top of the balls, not Make a design Result is a higher wear, a drop of efficiency and lower
          enough material if you don't see it)   throughput.
              Too much material may cause overfilling, a drop of 
              efficiency and lower throughput.
         
     
       
      6   Sampling of the second chamber    
        - Take 6-7 samples (inlet, 4-5 intermediate 500gr to 1kg for each In order to know the reduction efficiency of the
          samples at equal distance, diaphragm) sample second compartment.
        - Ideally for each sample, take materiel in three Mill-axis point is the It is more representative.
          points as shown on drawing below: best if 1 point  
         
     
       
        - Remove the balls and the material at the Depth of ±20-30 cm To collect the material only in surface is not correct.
          sampling point    
        - With the shovel, put balls and material in the   Don't forget to put possible uncrushed particles
          sieve which is above a paper bag. Remove the   with the material sample!
          balls from the sieve. Put the collected material    
          in a bag    
         
     
       
        - Check the presence of uncrushed particles, Visual estimation Accumulation causes blockage of the outlet diaphragm
          especially an accumulation at mill outlet   and a drop of efficiency and throughput.
          Don't discard uncrushed particles from the Especially at outlet It is important to know the percentage of
          sample diaphragm unground particles, in particular to the diaphragm.
      7   Outlet diaphragm    
        - Check the general aspect of the diaphragm Visual  
        - Check the condition and the wear of the plates Visual and To insure the protection of the diaphragm frame.
          and the grid plates thickness  
        - Check the width of the slots and if there Maximum width To insure that the slots of the outlet
          are blocked by unground particles or scraps Minimum width diaphragm are bigger than the slots of the
            % of area blocked intermediate diaphragm.
        - Check the condition of the central screen Visual estimation To prevent the passage of balls.
        - Check the condition of the water injection Visual inspection Maybe, it is useful to make a test in order to see
          system and if it is blocked by material (nozzle)   the trajectory of the water jet.
         
     
       
         
     
       
               
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