The methodology you use to determine the weight of the stock pile can be related to the reason you need the weight in the first place.

If you are just interested in a nominal value for general inventory purposes, take a few grab samples and use the average bulk density.

If some one wants to buy the whole stock pile based on a price per unit weight, I suggest you take numerous samples and make a surveyed dimensional analysis of the dimensions to arrive at a reasonable figue.

If your ground is sinking under the weight of the stock pile, you'll want to use the compacted density for design purposes.

Regards ■

Hello,

I've worked with a few companies in the US that do stockpile inventories of coal piles at utilites. The process as I understand it is to determine the density by core drilling the piles, inserting a nuclear density gauge and by mapping the pile. For more info, the companies I've delt with were SGS, LR Kimball, and Mikon ■

Much depends on the nature of the bulk material and whether it is sensitive to compaction. Coarse granular materials tend to sustain considerable stoage pressures with little change in density from a settled condition, whereas fine powders will compact with pressure. When measuring the density of coarse granules it is necessary to recognise the effect of the container walls in inhibiting the packing structure, so a relatively large vessel should be used for determining the density. By contrast, a small cell is sufficient for a fine powder and the effect of overpressure easily established by suitable loading. As there is no support from hopper walls in a stockpile, the compacting load at different bed depths is also easy to calculate, provided that the surface profile can be assessed with reasonable accuracy. Average values for different layers should be sufficient to determine the mass for products that significantly change in density with compacting load. ■