Estimating Bulk Densities of Mixed Products

Cells of a Raw Soybean
Bulk density is an important metric in many things such as bagging or conveying, which we’ve written about in this past blog.  Many websites and resources feature bulk densities of known products such as whole soybeans, ground soybeans, corn, etc, but what do you do if you’re trying to determine something new?  There are several times when you may have to decide on a mixer or bin capacity that will contain several different products with different bulk densities.  How would you calculate this?  With some simple math and some patience, you’ll be able to determine these answers.
What You Need
To start, you will need to know some existing densities of products.  As mentioned, there are several resources that have a good range of known products.
As an example, let’s assume we have a formula with the following blend percentage for 1 ton (2000 lbs) of final product:
–   Coarse cracked corn: 70% (1400 lbs)
–   Ground soybeans: 20% (400 lbs)
–   Cracked wheat: 10% (200 lbs)
From various sources, we know the following estimates:
–   Coarse cracked corn bulk density: 40 lbs/cubic foot
–   Ground soy bulk density: 35 lbs/cubic foot
–   Cracked wheat bulk density: 45 lbs/cubic foot
How to Calculate
An easy method is to multiply the bulk density by their respective percentages, then add everything together.
–   Coarse cracked corn: 70% x 40 lbs = 28 lbs
–   Ground soybeans: 20% x 35 lbs = 7 lbs
–   Cracked wheat: 10% x 45 lbs  = 4.5 lbs
Adding these together gives an estimated bulk density for the product of 39.5 lbs/cubic foot.
You can do this for as many ingredients as you have by using the same methods described above and then adding the values together.
If you are interested in an alternative method, you can do the following:
–       Take the individual weight of each ingredient,
–       Determine the total volume of all ingredients, and then
–       Take the total weight divided by the volume
This will give a slightly different value, but the difference is negligible. If you have any questions regarding bulk density calculations, give us a call, we’re here to help!
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