Unsolved Sand Testing Mysteries – Update!

When I was younger, I used to love the tv series “Unsolved Mysteries,” with Robert Stack. Mr. Stack would be in a trench coat every episode, with clouds of fog rolling in the background.

At the end of some episodes, they would feature an update, “Solved Mysteries.” In some cases, the show itself had led to the mystery being solved!

Today, let’s “solve” a few sand testing mysteries that might be bothering you.

1. My sand is pure white, can it be used as frac sand?

Getting into the frac sand market requires a lot of factors going your way – strength of the sand, transportation logistics, your ability to get the sand cleaned economically, and a great many other things.

My area of expertise is doing some lab testing on your sand to determine its performance, primarily its crush strength. I have other experts to refer you to, with regards to the other areas and pricing, etc.

Crush strength is a key measure for how the sand will perform down hole, so it makes sense that crush strength is a primary factor for an engineer deciding what kind of sand he will send downhole.

In my experience, the crush test – even an initial crush test – is the most objective way to get an idea of whether or not your sand can become frac sand. With regards to its color, I have seen low AND high strength white sand, and I have seen low AND high strength brown sand! You don’t know until we get it into the crush press.

We test proppants like fracturing sand2. What stress should we crush sand at?

There are 2 schools of thought here, and I usually recommend one or the other depending on a client’s circumstances.

The first school of thought is that we do the initial crush at the API recommended stress (ie 4,000 psi for 20/40 and 30/50 sized sand, 5k psi for 40/70 and 70/140 sized sand) and see how it performs against their table.

The second school of thought is to do a market based approach. For instance, we might recommend a 7k initial crush test for 40/70 or a 9k crush test for 70/140 sized sand. Then you can compare those results to a market board for frac sand (ie DownHoleTrader.com).

So, after discussions with our clients, if they aren’t ready for a full K value, we can recommend single stress crushing using one of those 2 strategies.

water well packing sand3. How do I know all the different markets that my sand can be used for?

I wish that I could give you an easy answer here, but I can’t!

That’s because the sand and aggregates markets depend on SO many different factors, including location of your deposit, ease of mining, ease of cleaning, silica content of your sand, strength of your sand, marketing ability, and much more.

But don’t get discouraged!

First off, you can easily find out the silica percentage, along with any impurities (such as aluminum oxide, and iron oxide) using XRF testing (we can do that for you).

Second, you can do frac sand testing – affordably! — using an initial testing package (we can do that for you). This lets you know whether or not your sand meets some minimum requirements for frac sand (primarily, crush testing).

Third, I have experts that I can refer you to for help once the sand is tested. Jen at Down Hole Trader is a great resource in the frac sand market, and my colleague Marvin is a world class sand and aggregates mining engineer and marketer.  Just ask if you would like me to refer you to them.

So, we stand ready to help you solve your sand mysteries, contact us here to get started.

Additional tips and tricks for sand and gravel sampling

I was talking with my colleague Terry Stransky from Terracon about doing sampling and testing for sand deposits.

He sent back some great info, especially as it relates to evaluating sand for traditional sand and gravel operations.

Take it away, Terry!

“You should note that for initial source evaluation we typically do one boring for each ten acres. We also recommend doing borings, not surface sampling, to the anticipated depth of the deposit, or the presumed depth of mining, as sand and gravel deposits can be notoriously inhomogeneous. Laboratory testing, even for just sieve analysis, will be dependent on what the borings show.

Typically before we do any exploration program, whether for sand/gravel operations or for stone quarries, we want to look at available geological information: bedrock geology, glacial geology and other surface geologic maps, topographic maps, groundwater resource maps and aerial photographs. If there are already pre-existing boring logs for a site or in a general geographic area, we like to look at those as well.

Once we have reviewed those, we need to look at things like how large the site is acreage-wise, how thick the deposits are (based on the reviewed information described above), depth to groundwater, which may determine how much of the deposit is economically minable etc.

The “rule-of-thumb” of 1 boring per 10 acres is just that. It is usually a good starting point , and results of the initial borings may help define further exploration targets. Typically, we don’t sample every foot of each boring at this stage. Depending on the anticipated thickness of the deposit and depth to groundwater, we might sample every 5 feet or at a change in lithology of the deposit.

Laboratory analyses might include grain size distribution curves, limited petrographic examination (especially for roundness and spehericity if we’re talking about frac sand), full petrographic examinations if we’re talking about a potential concrete aggregate source, etc.”

Here’s Terry’s info, if you would like to talk with him on your evaluating sand, especially for sand and gravel quarry use:

Terry Stransky, PG
Senior Geologist/Petrographer
Terracon Consultants, Inc
Cincinnati, Ohio
Direct 513-612-9081

How to sample and send multiple sand samples for frac sand testing

There are some important things to remember when sampling and testing across a sand deposit, especially if you are considering the frac sand market.

If you are considering doing such a project, you might want to consider the following process.

Here’s one way to map a deposit for frac sand testing.  A1 through A8 designate spots where you would sample from.  Remember to label each sample with its location.

1. Map out the sand deposit

Your mapping does not need to be perfect, but this will help your sampling techniques, and is good engineering practice. Just print out — on large paper if possible — a Google map of the property and sand deposit in question.

Then, in red marker, outline the sand deposit on the map. Then, select a few spots around the deposit to sample. This may be very dependent on your budget. For instance, we have worked with clients who can afford to samples dozens of times, and other clients can only sample 3 times from a deposit,

2. Sample according to the map, label the samples

Now, head out into the field and use the map to sample. If gathering surface samples, make sure that you dig down past any surface contamination, and into the deposit, so that your sample is representative of the deposit at that sampling location. Take at least 5 pounds (3 kg) per sample. At least that much.

For some projects, it may make sense to take 3 samples in an area, then combine those into 1 composite sample for testing. This is a hypothetical, and might not apply to your specific project.

Important! – when sampling, label the sample with a descriptive term (or even better, GPS coordinates!) from your deposit map. This will help later on, should the samples vary in quality. You will know exactly where each sample came from. And using the map you made, you can see how the quality varies across the deposit.

3. Arrange testing with a laboratory

At the very least, you will want a sieve analysis, and initial crushing done on fractions within the sample.

One of the most objective tests that you can run is first a sieve analysis, and then crush testing on the various fractions in the sample. For example, the sieve analysis might show that 40/70 and 70/140 (also known as 100 mesh sand) are very prominent in the sample. In this case, it might make sense to do an initial crush test on both those sizes at 5K, to see how they crush.  Or, just crush right away to K value.

You should be able to find a lab that can work with you and your budget to come up with some testing options. With some labs, you can call ahead of time, and they should be able to provide you with an estimate for number of samples and a variety of testing done with those samples.

In our lab, once you get above 5 samples, we can start to really show you some “package deal” savings.

If you are looking for a laboratory that is very good at working with clients to sample and test multiple samples, you might try us.

A deeper dive into Bentonite

(1) Minerology of bentonite – Bentonite is a type of clay called the “mineral of a thousand uses”. Bentonite consists mostly of one or more members of the smectite-group (formerly the montmorillonite-group) minerals.

(2) 3 variants of bentonite –

– Swelling bentonite (aka sodium bentonite) swells in the presence of water and is usually used in its natural state.
– Non-swelling bentonite (aka calcium bentonite) is typically treated before using
– Lithium rich “hectorite” which is commercially mined only in the US

(3) Properties of bentonite –

Bentonite has a very high surface area, and it is valued for its ability to bond, swell, seal, and its rheology features.  Chemical properties – bentonite has the ability for “cation exchange” which means that bentonite is very good at purifying and absorbing unwanted chemicals and toxins.

Bentonite Uses Graph courtesy of USGS

Bentonite Uses Graph courtesy of USGS

(4) Uses of bentonite

There are many uses of bentonite, and multiple markets to sell bentonite into. These industries and products include:

– Absorbents for pet waste (ie kitty litter)
– Adhesives
– Animal feed
– Drilling mud (ie drilling grade bentonite, tested in accordance with American Petroleum Institute standards)
– Filtering, clarifying, decolorizing of oils ( ie : Animal, mineral, and vegetable oils and greases)
– Foundry sand
– Pelletizing of iron ore (these pellets are the raw material for foundries, and bentonite is used as a binding agent during the pelletizing process)
– Waterproofing and sealing
– Miscellaneous uses which includes miscellaneous absorbents, ceramics, refractory sales, and filler and extender applications

bentonite-mining-and-uses-global-energy-labs-picture(5) Bentonite mines in the US

There are just a handful of bentonite producers in the US, and they produce nearly all the bentonite from the Wyoming area:

1 – Minerals Technologies Inc, (MTI) which is the world’s largest producer of bentonite, with mines and plants at Colony and Lovell, Wyoming
2 – Bentonite Performance Minerals (now a subsidiary of Halliburton), also in Colony and Lovell, Wyoming, with a corporate office in Houston, Texas
3 – Black Hills Bentonite, with at least 5 Wyoming locations
4 – Wyo-Ben, with corporate office Billings, Montana, and 3 plants in Wyoming

(6) Bentonite pricing (mostly 2013 pricing)

Here are some estimate of what bentonite sold for in 2013:
– Swelling bentonite – average price for US – $65/ton
– Non-swelling bentonite – average price for US – $75/ton
– Bentonite for iron ore pelletizing – $73-$79/ton
– Foundry grade bentonite, bagged and shipped in railcars – $107-$137/ton
– Pet waste absorbent grade bentonite – $55-$66/ton
– API drilling grade bentonite (2013 prices, keep in mind) – $99-$143/ton

(7) Bentonite testing

If you would like a bentonite sample tested to find out what its qualities are and what markets you might be able to sell it in, we can put together a customized testing package for you, according to what your budget is — go here.