Self-heating of vermiculite problem

[SkyKuba88]

Hello,
Since I have a lot of flies in my terrariums and braplasts, I recently started testing a substrate made of 100% vermiculite. I noticed that after pouring it out of the factory packaging, the vermiculite starts to heat up quite a bit (in contact with air). You can clearly feel the temperature rise when you touch it with your hand. Has anyone encountered such a situation and can tell me why this is happening?

I did the tests today. Within 6 minutes, the vermiculite heated up 3.5 C degrees higher than the ambient temperature. (You can see everything in the video, which I deliberately sped up so that you don't accidentally fall asleep during the session ) I recorded until I had enough patience, and the results were similar with 5 containers. I am also attaching a photo of what it looked like at the end. I know that these thermometers are not very accurate, but it's nice to see how the temperature rises after placing it on the vermiculite. Thanks in advance for your help
UPDATE: vermiculite only heats up during the first contact "with air". After a few minutes it cools down and the problem does not recur.

 

[Andrew Clayton]

You sprayed it with water. What's the temperature of the water? Vermiculite is a widely used mineral with impressive insulation properties, but it does not generate heat when in contact with air.

vermiculite only heats up during the first contact "with air"

Vermiculite isn't vacuum sealed so there is air in the bag.

 

[jennywallace]

Yeah I've never known vermiculite do that.

 

[SkyKuba88]

I don't know what the water temperature is, but it's cold tap water, it definitely wasn't hotter than 10 degrees Celsius. The vermiculite was heating up before it came into contact with the water (the video shows it a bit misleadingly). I think it's some kind of oxidation process, but I'm not sure. If so, I wonder what the products of this oxidation are and whether they're healthy for spiders...

Wermikulit nie jest pakowany próżniowo, więc w worku znajduje się powietrze.
[/CYTAT]

I know, that's why it surprises me...

 

[viper69]

Never had that happen ever

 

[SkyKuba88]

My theory is that this vermiculite is waste and not entirely pure. I will only add that this has only happened to me with a product from this one particular manufacturer.

 

[Glorfindel]

seems like it was in the process of curing

 

[Ultum4Spiderz]

My theory is that this vermiculite is waste and not entirely pure. I will only add that this has only happened to me with a product from this one particular manufacturer.

Weird it heated up. I wanted to buy vermiculite but the seed shop wanted $60 so I passed and bought top soil .

 

[Brewser]

I've never used vermiculite as a substrate in arachnid cages..

I use a local dirt mix.

 

[Charliemum]

I mix vermiculite in my sub mix never had this happen, must be something wrong with the bag . I wouldn't use it just incase. Stick to top soil but watch it doesn't have any thing in it, most have organic fertiliser in took me ages to find one without it althoughi am uk may be different where you are.

 

[Wolfram1]

interesting in any case, isn't vermiculite expanded artificially through heat?

perhaps the recently expanded/fresh vermiculite stores some of that thermal energy and releases it upon contact with oxygen or water

 

[The Snark]

If you have reason to believe the vermiculite is contaminated, it should also be suspect of having asbestos. Possibly processed without adherence to regulatory measures or use of questionable materials.
" Impure vermiculite may contain, apart from asbestos, also minor diopside or remnants of the precursor minerals biotite or phlogopite."
Properly processed vermiculite is stable, non toxic but notably hygroscopic.

 

[SkyKuba88]

Up until now I used coconut fiber (if there were live plants in the terrarium, then with a touch of soil for herbs/flowers - no artificial fertilizers), but the number of flies started to scare me. With vermiculite the problem disappeared (in the containers I used it in). I will check with vermiculite from another manufacturer and let you know how the situation was. I will also try to do some comparative tests. As for regulatory issues and asbestos - it is possible, because I ordered vermiculite from a start-up company that sells accessories for terrariums - who the hell knows where they get it from.

 

[Tentacle Toast]

Sounds like you need a Geiger counter & some potassium iodide pills. Where did you get this stuff?

 

[The Snark]

I will check with vermiculite from another manufacturer and let you know how the situation was. I will also try to do some comparative tests.

Sounds like your best move. But doing your own comparative testing. Probably safe. Anybody trained in chemistry from year 1 college students on up will suspect something weird is going on.. Essentially 'sounds like somebody sifting mine tailings and thought of a way to make a quick buck. Tailings could be discards due to the presence of sodium or other exothermic material'.
Sodium for one is very common in many mineral extraction operations and considered a nuisance metal. From word go, the metal's exothermic properties do exactly what you described. Presence of water, starts to heat up. Unwanted chemical reactions galore. The operation ends up with various salts contamination to deal with. Extra measures have to be taken in processing, and the cost of taking those measures can put a dent in board room bottom lines.**

As for regulatory issues and asbestos - it is possible, because I ordered vermiculite from a start-up company that sells accessories for terrariums - who the hell knows where they get it from.

As for asbestos, the international ban on some forms is pretty much universal and has been in place for over a half century. But as such, it can be taken for granted. Importing or exporting materials containing it will pretty much assure doors slamming shut and fire up the relevant government agencies to shut down or blacklist the rogue operation moving the contaminated products. But using an unrelated phrase, 'unsafe at any speed'. You don't want to have anything to do with it as it hands you an unwanted present for the rest of your life. Not worth taking chances like experimenting with possibly contaminated material.

The raw materials for making commercial vermiculite; the presence of that asbestos is quite common and one reason mining operations will abandon an extraction site.

**A retired chemist down the street from me worked at a mining company for years. Silver extraction. AgNO3 + NaCl = AgCl + NaNO3 and other related chemical reactions. Extra processing steps required. A constant problem cutting into their profits.

 

[TheraMygale]

Please be careful for your health.

put on gloves just in case and don’t breath that dust! Without a mask you are breathing it.

it is not something to take lightly.