My colleague Clive Woodford involved me in a project for an explosives manufacturer. He was asked to make detonator coolers to prevent premature explosions in hot blastholes. His solution was too expensive. I did a lot of basic R& D and eventually solved the problem. Our goal was to keep the detonator below 137°C for half an hour with the temperature at 1000°C in the hole.
We have achieved it and want to demonstrate it. The client did not buy the technology and we are looking for new clients.
Sometimes coal seams ignite underground, and smoulder very slowly because it takes very long for oxygen to get down there. If you drill blast holes into such a seam, you suddenly let fresh air in and the temperature goes screaming up to 1000°C. Then they put a detonator down, and pump dynamite down the hole. The detonator overheats and explodes when it reaches about 137°C. I devised a super insulation capsule to delay the heat transfer. I cannot find a case of this actually happening, but if it does happen while dynamite is being pumped from a tanker, the destruction will be devastating. I think it unlikely that I will sell lots of insulators, but am hoping that an explosives manufacturer will buy the technology and some insulators and offer it to his coal mining customers, just to cover his arse. If they don’t buy it, and the shit hits the fan, he can show that he has done everything he can to prevent this catastrophe, and is therefore blameless. I can’t guess what the implications would be in SA, but in the USA this could be viewed as a very handy “insurance policy.”
If I could find the right guy in the USA to sell it, he could possibly sell it to several manufacturers, perhaps some mines too. Maybe he could get several million US$ for it, give a cut to everyone along the chain, including me and you. Do you have contacts who could perhaps get the ball rolling?
Dave Onderstall of Keramicalia and Clive Woodford of Mirja ceramics.
Below I have attached some background information. I have patented the technology and would like to sell the patent. Otherwise Clive and I can manufacture the product for you.
Tests are going well. I left the file at work, but here are some results;
I found many products with high porosity and high strength. Kerafire is one of the best, about 50% porosity by volume, and it absorbs 50% water.
Here is my little Heraeus furnace at 1100°C. I put soaked specimens in at between 1100°C and 1200°C to check if they explode.
Kerafire at the back and ceiling board in front after 10 minutes.
The little one at the back is Plaster of Paris, The curved one is Insulag boiler plaster, the square one is calcium aluminate bonded board and Harmonite in front, before firing
After firing, Insulag is melting, PoP a bit buggered.
Darling mix right, a blob of sorel cement behind it and microporous insulation on left.
After cooling; Calcium aluminate board looks best. Kerafire got damaged during handling while hot.
The Heraeus burned an element, busy repairing the brickwork. Next I would like to clad detonator containers with Kerafire and return them for testing.
Subject: Hot hole simulation
Our test rig took a long time to perfect. The biggest problem is that when you place the cold capsule in the furnace at 1000°C, the temperature drops. The solution is to place high thermal mass sleeves in the kiln to stabilize the temperature.
Fig 1. Heat stabilizing sleeve on left, capsule on right.
Fig 2. Sleeves in the kiln.
The next problem is heat loss on opening the kiln. We now have built a dedicated kiln with holes through which to insert the capsules.
Fig 3. Kiln with holes plugged by bungs. The one on the right has a thermocouple inserted. The instruments above it record the kiln temperature and the temperature inside the capsule.
Fig 4. A thermocouple is inserted through a bung.
Fig. 5 The false lid for the thermocouple.
Fig. 6 The real lid with thread and groove for the cable.
It seems that we now have a real simulation of a hot hole. We start the test at 1050°C, and it drops but recovers, giving roughly an average temperature of 1000°C over the test.
We have now achieved the goal of 30 minutes below 137°C inside the capsule.