I was watching Modern Marvels (or something like it) last night and they had this machine that looks like a twelve foot chain-saw, which was pretty wild looking I admit, but that isn’t the interesting part, read on.
Anyways, instead of it cutting wood, it has a large belt that cuts granite, marble and other types of stone for counter tops and bathrooms. On the aforementioned belt, there are sections all along it that have “construction grade” diamonds embedded into it that are used to cut these different types of stone.
Makes sense because if you have something hard to cut, find something harder to cut it with, hence the diamond belts.
Now to the question. They say each belt cost roughly $8750.00 and the belt needs to be replaced after 375 hours of usage. What they didn’t state was what they did with the belts and/or the “construction grade” diamonds after each use.
So, what do they do with the used diamonds? Just throw them away? Do they try to use the diamonds for anything else? Surely there are people out here who would buy the diamonds and maybe even make art projects out of them or something.
Because if they do just throw them away, that would seem like a waste. Hell, I would even drive up to the Pennsylvania quarry and bring the old ones home and pick out the diamonds myself. lol
Well, for one, the diamonds are unfinished and not suitable for putting into jewelry, hence why they are used in construction. I imagine the diamonds on the used belts are taken off and maybe reworked some more and put into another application, maybe a smaller diamond coated saw/blade for home use.
Industrial diamonds are dirt cheap these days. You can walk into any hardware store and buy diamond cutting tools for dollars. If I’m reading this report (PDF warning) right, it looks like commodity diamond grit costs about 25 cents per carat, and industrial grade stones cost around $10 per carat.
ETA: In other words, at that price, it may not be worth trying to recover the stuff.
The actual diamonds tend to be very small - sort of like grit.
As lazybratsche notes, such saw blades are common and cheap (link). You can find them at any Home Depot store (though probably not in the 12-foot, $8750 size).
That’s my understading, I usually hear it called diamond dust, not really useful for much else. Also, I don’t think you’re going to pick it off to use it for something else. If it hasn’t fallen off after 375 hours of cutting granite I think the average homeowner will have a hell of a time trying to do it themselves. Also, I woulnd’t be surprised if the belts themselves are re-used.
When my father was employed to make diamond dental drills in 1950 (they became obsolete around 1960 with the invention of the high speed drills–diamond bits cut too readily and were hard to control, while carbide was just right) white industrial diamonds cost about $5 a caret (0.2 g). The only reason they insisted on white was esthetic. At that price, they were worth recovering (by dissolving off the nickel plate that held the diamonds on). Later on they turned to making diamond cutting wheels and core drills. The latter were sold mainly to Corning Glass for cutting out glass stoppers and holes in glass. They were made by plating the nickel and diamonds an aluminum base and then punching out the blank, leaving a thin shell. They then used any color diamonds and they were a good deal cheaper.
Basically, the diamonds aren’t there any more.
That’s why they are replacing the belts after 375 hours – the diamonds have been worn down so they no longer cut. Just like sandpaper; after enough use, it no longer works, so you get a new piece of sandpaper.
A company I worked for sold and stocked the things. By the time the belts are worn out, the diamonds are gone and the belts are just discarded. But the diamonds are very small, measured in the same grit sizes that aluminum oxide or silicon carbide belts are measured. The reason the diamonds are gone is because what happens is that the substrate holding them in place burns away during usage, and the tiny diamonds are simply dispersed with the dust. This process constantly reveals new levels of substrate which reveals new diamonds and so on until it has all be used up.