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MTi Group USA Operating across the USA and Canada, MTi USA is your go-to supplier in industrial and mining consumables in North America

10/08/2026

One customer's review, word for word.

"Very high quality."

Five stars on the Blast Hole Temperature Probe. It's the probe this week's field guide names for reactive ground and hot holes: 30 m of K-type line marked every 0.5 m, on a reel built like MITIMEASURE. Measure the full length of the hole, check it against the explosive's maximum loading temperature, then load.

Product link in the first comment.

10/06/2026

Two ways a blasthole gets too hot to load.

If the rock is rich in unstable sulfides (like pyrite) it begins heating up on its own through a chemical reaction. The longer that hole sits, the hotter it gets.

There are coal seams that have been burning underground for years. Drill new holes near or through one of those and the holes become extremely hot from close proximity or contact with the fire below.

Every explosive has a maximum loading temperature. Exceed it and the explosive will degrade or even ignite during loading. That's a catastrophic safety event, not a near miss.

When in an area with reactive or hot ground, measure the full length of every hole, not just the top and bottom, and not random holes here and there. Check it against the product you're about to load. Then decide.

Full field guide: https://www.shop.mtigroup.us/blogs/articles/reactive-ground-and-hot-holes?utm_source=facebook&utm_medium=social&utm_campaign=2026-10-reactive-ground-hot-holes&utm_content=video

Some holes are too hot to load.Two different conditions produce the same problem: a blasthole that's too hot to load saf...
10/05/2026

Some holes are too hot to load.

Two different conditions produce the same problem: a blasthole that's too hot to load safely.

Every explosive has a maximum loading temperature. Exceed it and the explosive will degrade or even ignite during loading.

Nine slides. Guide link in the first comment.

You can't always see wall damage from the surface. So to test back pressure on the wall, this mine drilled "witness hole...
10/01/2026

You can't always see wall damage from the surface. So to test back pressure on the wall, this mine drilled "witness holes" into the step bench: holes it never loaded, on the production burden and spacing.

Check each one before the shot with a camera, count the fractures. Fire. Check them again.

With 3 m (9.8 ft) air decks in the buffer row, damage fell off hole by hole and nothing collapsed. Without them, the closest witness hole caved in and the next one back more than doubled its fracture count.

Same pattern. Same explosive. The only change was a gap of air where the buffer-row product used to be.

Full case study in the first comment.

09/29/2026

The hole looked completely normal the entire time you loaded it.

Then it fires, and gas comes out the face sideways, and it takes rock with it.

That's the crack nobody found. A face hole drilled through a crack that runs out to the open face. The driller never felt it, or didn't mark it. No sign of it during loading. The crew finds out at detonation.

Cracks and voids do the same thing in less dramatic ways all the time. Gas vents before it does useful work. Confinement drops. Explosive runs into a void and inflates the powder factor for that patch of rock without breaking anything useful.

You can't plug what you haven't seen, which is the whole argument for putting a camera down the hole before you load it. Plenty of crews use sewer cameras because they're cheap. They work. They just don't last long in that grit.

And a fair number of these are ours to begin with. Cracks left in rock by a previous shot, sitting in the bench somebody's going to drill next month. If you know where the next bench is going, you can air deck the row closest to it and slow that row's timing, so the energy moves away instead of into it.

Full field guide in the first comment.

The hole looked fine the whole time you loaded it.Cracks and voids give explosive gas somewhere to go other than the roc...
09/28/2026

The hole looked fine the whole time you loaded it.

Cracks and voids give explosive gas somewhere to go other than the rock you meant to break. The one that gives no warning is a face hole drilled through a crack that runs to the open face.

How to see them, what to plug with, and how to stop making them for the next bench. Nine slides.

Guide link in the first comment.

09/17/2026

On a bench you've got a free face. Underground, driving a heading, you don't. You have to make one.

That's why a development round is drilled as a bullseye. A tight cluster of holes at the center, then rings spreading out from there, all to about the same depth.

The center fires first and opens a void. Then each ring collapses inward toward that space. The whole sequence is over in less than a second.

Get that order wrong and the round doesn't pull, because there's nowhere for the rock to go.

The other thing that makes development different is diameter. These holes run about 1.25 to 5 inches vs 4 to 12-plus on a bench. Most are loaded with packaged or cap sensitive explosives. Smaller holes require smaller plugs and accessories.

Then you muck it out, bring the bolter in for ground support, and drill the next one. 10 to 30 ft a round, every crew waiting on the one before it.

Full field guide: https://www.shop.mtigroup.us/blogs/articles/development-rounds-the-center-goes-first?utm_source=facebook&utm_medium=social&utm_campaign=2026-09-development-rounds

09/15/2026

That yellow-going-orange cloud hanging over the shot has a name and a cause.

The name is nitrogen oxide. The cause, about 99% of the time, is water.

Standard ANFO burns around 12,000 to 16,000 fps. When water gets into it, in the hole or back in storage, it fires at low order instead. The explosive begins to break down, and instead of releasing nitrogen the way it's supposed to, it puts out NOx.

Standing in that cloud can kill you. And on some shots it can get large enough to drift toward somebody's house, which stops being an environmental complaint and starts being a serious incident.

The fix isn't complicated. It's a decision you make hole by hole.

If it's wet, or it might get wet, line it. If you can't dewater, load emulsion, it's waterproof by design. If you're able, dewater, line it, and load ANFO, which is still the cheapest bulk going in the ground. Pick the liner by hole diameter and depth.

Australia's fume regulations are stricter than ours, and almost every Australian coal mine lines holes to stay in compliance. There's a reason for that.

Full field guide: https://www.shop.mtigroup.us/blogs/articles/fume-why-the-cloud-turns-orange?utm_source=facebook&utm_medium=social&utm_campaign=2026-09-fume

09/10/2026

Some of the holes in a long-hole stope break through into the next level. That's by design.

Which means before you load them, those holes need a bottom. Something at the breakthrough for the explosive column to sit against.

Crews have solved this a lot of ways over the years. A wooden dowel or wedge on a knotted rope, lowered and tied off so it sits just above the breakthrough. Or a stick of powder roped at its middle, dropped until it flips sideways past the opening, then pulled back so it wedges in like a toggle bolt.

Both work. Both are slow, and neither one gives you a repeatable seal.

Easiest field check there is: kick some dust into the collar. If it hovers at the top without moving, you're sealed. If it takes off, you're not.

What actually holds it: a BLASTBALL just above the breakthrough, a BLASTBAG AERO when you need depth (it only inflates once you hit it with compressed air), and a SLUMPSTOPPA at the collar so gassed emulsion has somewhere to vent while the column stays put.

Wrote up the whole thing, breakthrough plugging, the uphole order of operations, and why gassed emulsion needs room to grow. Full field guide: https://www.shop.mtigroup.us/blogs/articles/long-hole-stoping-holding-the-column?utm_source=facebook&utm_medium=social&utm_campaign=2026-09-long-hole-stoping

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40380

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