In a previous blog post on
material blending we touched on some of the reasons
why a user might want to employ material constraints while blending multiple
aggregate products. I would like to
expand on those reasons and add a few more to the list. The mathematical and visual blending tools
available in
StonemontQC for aggregate, asphalt and concrete materials are very
robust and powerful. Each of these
blending tools will allow the user to constrain the aggregate blend percentages
while attempting to meet a specification or target. There
are many practical reasons to constrain the percentage of materials used in a
blend.
Ensure the Use of Low Cost or Waste Materials
Cost conscious producers know that incorporating suitable low
cost surplus material into their blends not only helps off-set the use of more
expensive materials but has the added benefit of using stockpiles of a product
that might otherwise need to be hauled away at an additional expense. Many of these by-products go through the same
plant processes as any other material and are of the same inherent
quality. Just be sure that the materials
are properly tested and suitable for the intended purpose. Set a minimum percentage of these materials
in your blend and start using your waste piles.
Create a Better Balance of Material Consumption
Aggregate sources don’t produce all materials at the same
tons per hour. Rarely does the demand
for products match the plant’s output either.
Setting up blend percentage constraint’s that more closely match a
source materials output and demands can help keep plants in balance ensuring
that every rock gets sold. This takes a
special attention to detail and a thorough evaluation of inventories and production
and shipping tonnages.
More Accurate Batching
The aggregate blend looks absolutely perfect when you use
just 2% of that blend sand and in theory it will be the most pump-able concrete
product ever produced. But will you ever
be able to accurately batch that small amount?
Batch plants attempting to jog-in just the right amount of material into
the weigh hopper often miss the mark when the mark is too small for the given
weigh unit (such as 20 lb increments). Furthermore,
attempting to use such small material amounts, especially for fine sand
material, can cause the material to bridge over the gate stopping the flow of
material to the blend. If you open the
gates some more or jog them, all at once you got the sand you wanted and then
some. When developing the blend, set the minimum constraint to a percentage
that will provide sufficient material that can be accurately weighed and
batched resulting in a smooth running plant.
Shorter Batch Times
So you opted to keep that small percentage of material in
the mix after all. Your batch plants
computer can handle it right? You got the
jog times so small that you know that it will batch accurately. The problem is, now that batch takes a lot
more time to complete. Increasing batch
times by only a matter of minutes can have a trickle-down effect making each
load even later then the last. Creating
blends that are more constrained to have a reasonable amount of each material
not only speeds up the process but makes for happy customers when their
deliveries are on time.
Maintain Specific Material Properties
Sometimes it’s not just the material gradation that
matters. You may be looking to maintain
a specific combined specific gravity or total fractured faces in the
product. Creating percentage restrains
on key materials can help maintain those other blended material properties
where you want them.
Limit Reliance on a Single Product
It is really convenient when you have an aggregate product
that works well in a blend. But what if
that product has an overweight contribution to the blend with a high
variability? Well, the high variability
of that single product will increase the variability of the blend resulting in
a higher probability of failures.
StonemontQC includes the Mix Risk tool to help evaluate the blend and
identify this situation. One solution
may be to set a maximum percentage constraint on this product and possibly add
an additional product to the blend with a minimum percentage constraint.
Minimize the Use of Expensive Products
Sometimes the best product is also the most expensive. Savings can be realized if you can minimize
the use of these really expensive products by constraining the maximum percentage
used and still create a great material blend.
The minimum and maximum percentage constraints also can be used in
conjunction with other tools such as minimizing the cost of the blend while
meeting the desired specifications.
Good luck on you aggregate blends and put those material
percentage constraints to good use.