Stockpile end cone correction

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Consistency is an important and inevitable factor in any process plant. To meet a consistent quality output of the product (for example steel or cement) the raw material shall be fed continuously for processing in the required ratio.
Consider a case in which the raw materials are stored in the stockyard in number of layers and during reclaiming if the consistency in blending is disturbed after sometime of reclaiming. The result will be change in product quality.
Case study:
Form a stockpile of 40m (Width) x 12m (Height) x 250m (Length) with 6 layers and discuss the consistency (mixture of all 6 layers of material) during reclaiming operation.
Machines used for stacking & reclaiming,
Stacker       - Luffing Stacker or Twin Boom Stacker
Reclaimer   - Bridge Scrapper Reclaimer or Barrel Reclaimer or Wheel on Bridge Reclaimer
(Note: above mentioned reclaimers are with harrow arrangement)

STOCKPILE:

Below sketch shows a stockpile of 40m x 12m x 250m (repose angle considered is 31°)


Side A - Starting point of reclaiming operation.
Side B - End point of reclaiming operation.


CASE 1:
Stockpile formed WITHOUT compensating the travel length and the reclaiming operation.






Referring the above sketches @side‘A’ and @side‘B’, it is clearly visible that,
·       @side‘A’, the consistency in reclaiming starts only after the reclaimer travelled for a particular distance. For the given stockpile configuration, this distance is 20m i.e., we get consistency in reclaiming only after travelling a distance of approx. 20m.
·       @side‘B’, the consistency in reclaiming ends after the reclaimer travelled for a particular distance. For the given stockpile configuration, this distance is approx. 20m from the stockpile end i.e., we get consistency  in reclaiming only up to a particular travel distance.
·       In total the consistency in reclaiming is only for 210m out of total 250m length of the stockpile.

CASE 2:
Stockpile formed BY compensating the travel length and the reclaiming operation.



Referring the above sketch @side‘B’, it is clearly visible that,
·       @side‘B’, the consistency in reclaiming ends after the reclaimer travelled for a particular distance. For the given stockpile configuration, this distance is approx. 40m from the stockpile end i.e., we get consistency in reclaiming only up to a particular travel distance.
·   Consistency in reclaiming is only for 210m out of total 250m length of the stockpile.

CASE 3:
Stockpile formed BY COMBINATION of compensated and non-compensated travel length and the reclaiming operation.


Referring the above sketch @side‘B’, it is clearly visible that,
·       @side‘B’, the consistency in reclaiming ends after the reclaimer travelled for a particular distance. For the given stockpile configuration, this distance is approx. 20m from the stockpile end i.e., we get consistency (mixture of all 6 layers of material) only up to a particular travel distance.
·       Consistency in reclaiming is for 230m out of total 250m length of the stockpile.

Conclusion:
Comparing all above cases, it shall be concluded that the consistency in reclaiming is maximum when the stockpile is formed by a combined compensated and non-compensated method of stacking.


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REFERENCE PHOTOGRAPHS







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