Tuesday, May 31, 2011

Stock Pile Segregation III-Building Stock Piles

My last two posts focused on avoiding segregation during production and load out.  This post will focus on avoiding segregation and degradation when moving material to a new location and building new stock piles.

When you are building aggregate stock piles you must be aware of the potential for segregation just as you do during production and load out.  The taller the stockpile is, the larger the chance for segregation, especially if you are stockpiling in a cone shape.  If you have ample floor space you should first consider a large stockpile that takes up a lot of surface area but is not very tall.  To make this type of stockpile you should be aware of how you are dumping the material to form the stock pile.

When using equipment that does not have a tall reach, like haul trucks, the operator should be sure that they do not dump the aggregate material onto the existing stock pile's side.  If the material is dumped on a sloped side of the stockpile, the larger rocks will tend to roll down the side of the stockpile and collect around the toe, just like they do in production.  Each time you have a new truck load, the truck should dump its load just in front of the stockpile to create a new cone of material.  A loader can come in after the truck to buck up the pile and move it all closer together if necessary.  This is shown in the picture below:

If you do not have the luxury of endless stock pile space (as most of us do not) you will probably want to make a taller stockpile to take advantage of the storage potential.  One great way to do this is with progressive stock piles like the one shown in the picture below.

Progressive stock piles are stockpiles that are made by adding one layer of aggregate at a time.  The haul truck dumps its aggregate material on the ground and a dozer pushes it up onto the stockpile at at slope no greater that 3:1 to prevent the larger rocks from rolling down the stockpile.  It is important that the dozer pushes the material up the stockpile to just before the edge of the stock pile on the other end.  If the dozer pushes the material over the edge of the stockpile you will have the same segregation problems that you are trying to avoid by not using a cone shaped pile.  When choosing a dozer to work on your stockpile, opt for the lightest one that you own.  The weight of heavy equipment on aggregate materials can crush the aggregates and make the product finer.  This is also the reason that a track dozer is recommended over a loader for this application.  The tracks of the dozer distribute the weight of the equipment over a larger surface area than four wheels does which in turn reduces the crushing force applied to the stock pile at any one time.  Because of this propensity to crushing, it is recommended that if you can avoid driving equipment on your stockpiles you should. 

What other stock piling solutions have you found?

1 comment:

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