Question about the resources needed in mining

[Evanish]

Hello,
I was wondering if the resources needed to extract some amount of a mineral from ore goes up in way proportional to the percentage that mineral makes up of the ore.

I'm not sure I'm expressing things clearly so I'll give an example. Let's say you have three ores. The only major difference between them is the percentage of Uranium in them. Ore A has 300 parts per million uranium, Ore B has 30 parts per million Uranium and Ore C has 3 Parts per Million Uranium. You have the same amount of resources to extract Uranium from each ore which we will call X.

If X could be used to extract 300 pound of uranium from ore A, then does that mean it could extract 30 pounds of Uranium from ore B and 3 pound of Uranium from ore C?

Somehow it seems to me that this might not be the case when what you are trying to extract only makes up a very small percentage of the ore, but I don't know much about mining to feel any certainty, and I can't seem to find the answer using Google.

 

[jim mcnamara]

There isn't a simple answer, mainly because the cost of extracting some elements is overridden by the need for it. So a few grams costs a lot of money. Other elements are tagalongs (if that is a word). Example: copper ores may contain small amount of silver, so while they are "at it" smelters extract silver, too. Other mineral resources like anthracite coal do not require smelting, maybe just some crushing and sieving. Gravel extraction and cleaning is a big deal near where I live. Most of the cleaning involves sand removal, so the final product after sieving is huge buckets each with a different "particle size". Sand, fines, base coarse, channers are some of the very old English names for these grades used for construction and landscaping.

You can get 'designer gravel' - different colors and types (alluvial -- called "river stones", crushed) of gravels. Which I think is interesting. Plus 'red lava rock' which is crushed volcanic tufa with iron oxide $Fe_2O_3$ in it, is also used extensively for sanding icy roads in winter. Obviously, designer anything immediately means the consumer pays more. It used to be sold by the yard (cubic yard) now it comes in small bags ~30lbs or at cement/gravel yard by the hundred weight. Your truck is weighed coming in and going out. Given the cost of extracting this stuff and the colossal markup I would seriously consider, if I were purely profit motivated, going into extraction, grading, and selling gravel.

Petroleum exploration and extraction, and refining is hugely expensive. The opposite end of the spectrum from gravel. And the resulting product, given the resources required, is not that expensive. Compared to gravel, anyway.

The point is that there is no one one perfect model. Pick a mineral resource, then you are "automagically" stuck with extraction, smelting/refining, and distribution costs you usually cannot avoid.

 

[256bits]

If X could be used to extract 300 pound of uranium from ore A, then does that mean it could extract 30 pounds of Uranium from ore B and 3 pound of Uranium from ore C?

Depends upon the resource - time, capital, labour, energy, finance, maintenance, processing, land.
Mine C would require more land for the greater volume of tailing so your supposition does not hold.
Processing of the ore of different quality - can't say. For example, if using chemicals, are the impurities dissolved/separated leaving the product, or is the product dissolved/separated leaving the impurities. Not sure am I how they do uranium.
Picking at the ore in the ground, let's use pick axes. One man can mine as much from mine A, B, or C in the same amount of time using his pick axe. same for a machine, so the supposition seems to hold. Except again, Mine A, B, C can wear out pick axes at different rates, so maintenance costs vary between the mines.
Canaries in a coal mine. If mining underground coal, would we need different numbers of canaries or the same for each mine?

Good question though as it sheds light on what mining companies must go through to analyze the profitability of a mine, and whether to proceed forward or not.

 

[Bystander]

See "clarke of an element."

 

[sr-latch]

Isn't Clarke of an element just the average concentration of an "element found in rock formations" ("Methods and Models for Assessing Energy Resources")? (Alternatively, the USGS defines it as the concentration as compared to the surface, rather than within the content you're extracting.)

Jim's right that petroleum exploration is pretty expensive. Long before you make a dollar of income (much less profit) you're going to first construct geological models, then have someone go out in the field with to perform initial exploration/surveying (initial coring equipment + 2 or 3 guys, maybe 500k?), to feasibility studies to see what your deposit is going to yield, followed by getting the mineral rights from the holders, all of the municipal permits... Then the cost of actually outfitting derricks, pumps, casing, drill strings, carbide rock bits if you're penetrating any rock with a Mohs > 6ish, maintenance on all the equipment, labor, insurance. You'll sell it to an oil trader (say, Vitol), they'll make 10% to sell it to someone like Marathon who will refine it and finally get it off to Chevron.

256bits is on the mark. There's going to be a lot of variance no matter what. You can definitely do it for 'cheap'. I.e., oil theft in Nigeria is commonplace. They'll hot-tap a live pipe, jack a ton of crude and create a make-shift 'refinery' hidden deep on the Delta, fraction off the gasoline and toss out the remaining 80% (what do they care, it's all profit essentially).

For your example (uranium), the method of obtaining yellowcake (~3.5-5% u235) from ore (~.7%) is to do the standard mine uranium ore -> ball mill crush -> slurry extraction with an acid. You then enrich (toss out the u238 junk!) just by using the mass differential between isotopes in centerfuges to hit your necessary u235 concentration s.t. you have a viable fuel source.

The yield I've read is somewhere between 25-30% by mass. I'd imagine as you try to refine further and further your yields go down monotonically (which is why when you saw those press pictures of the Iran centrifuges, they were processing insane amounts!). This doesn't really answer your question directly (you were asking if there was a linear yield co-efficient, I think?) the answer is "nope, and the general rule of thumb is the higher of a yield you want to get, the harder you have to try [in the case of uranium]". (More generally, it depends on the natural composition of your diggings, the processes you use to extract and refine (them tailings got some good stuff in em!), your marginal opex costs for the region (which will wildly fluxuate) and your capex (which is a bit more stable)).

 

[Evanish]

Thanks for the replies everyone. I learned a lot.

This doesn't really answer your question directly (you were asking if there was a linear yield co-efficient, I think?) the answer is "nope, and the general rule of thumb is the higher of a yield you want to get, the harder you have to try [in the case of uranium]". (More generally, it depends on the natural composition of your diggings, the processes you use to extract and refine (them tailings got some good stuff in em!), your marginal opex costs for the region (which will wildly fluxuate) and your capex (which is a bit more stable)).

That was what I was asking, thanks. What got me thinking about this topic in the beginning was my interesting in nuclear power, and my trying to understand how much energy that source could supply to people if we used fast breeder reactors, and how many years that energy might last us for. To do that I was trying to understand if there would be a positive long term EROEI (Energy returned on energy invested) for nuclear power if fast breeder reactors were used and normal (Clarke of Uranium?) parts of the Earth crust were mined to supply them with fuel. It seems like if that is the case the energy from nuclear power is practically limitless. If found some information about the energy use for mining Uranium in one instance, and was wonder if that could be used to to extrapolate the energy need to mine uranium from the average material forming the Earth's crust. From what I've read here I guess not.