[HN Gopher] Mponeng Gold Mine
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Mponeng Gold Mine
Author : marcinreal
Score : 67 points
Date : 2022-07-01 06:35 UTC (1 days ago)
(HTM) web link (en.wikipedia.org)
(TXT) w3m dump (en.wikipedia.org)
| Havoc wrote:
| If you ever get a chance to go down a shaft definitely do so. The
| really deep ones aren't open to the public generally but smaller
| ones sometimes do
| diego_moita wrote:
| This seems to be a place that words can't capture fully but
| images can.
|
| A documentary team went down there:
| https://www.youtube.com/watch?v=Lh8qecv7qbs
| roenxi wrote:
| The Wikipedia page doesn't mention the annual production of the
| mine - but a linked website suggests around 5.5t/annum.
|
| If you do the maths on that it is an absurdly small volume by the
| way. You could hide it under a blanket.
| mdorazio wrote:
| And yet if I did the math right, the gold mined each year still
| has a market value around $350M. Gold is really expensive.
| Havoc wrote:
| Those shafts are somewhat old & running out of steam. The next
| door shaft is still producing a bit more but you can see the
| same trend in the numbers
|
| https://en.wikipedia.org/wiki/TauTona_Mine
| loufe wrote:
| Mponeng is a mine of extremes. 4km of depth means immense
| pressures (just think maximum depth people can dive, static
| pressure increases lineraly with depth as the rock above needs to
| be supported (and rock bursts). The amount of engineering and
| resources poured in to support the tunnels and openings gets
| crazy.
|
| Not only that, but heat is a problem. Here in Quebec the mine
| Laronde is famous for its air problem. The typical pattern of
| ventilating mines is to bring air down these tall vertical
| passages (raises) to just about the bottom of the mine then let
| it pass to the surface through workings. Cold air in the winter
| at high speeds means ice build up on the raise wall, which risks
| decreasing airflow in winter (smaller passage) or
| flooding/falling ice in summer. So the mine Burns propane in the
| stream of incoming air. However, the mine is more than 3km deep,
| so the ambient temperature of the rock grows as that same air
| continues down, and at some point you reach greater than safe
| working temperatures, so that exact same air is AC'd further down
| on a massive scale so the humans and machines can work safely at
| the bottom. What a headache.
|
| I don't know many specifics about Mponeng but I did was a doc on
| Youtube about it a couple years ago which miners following very
| narrow gold seams, reinforcing the opening with blocks of wood,
| which even they felt weren't safe (wood would only last a short
| bit of time). Travel time also becomes a big consideration.
| Workers in most mines travel from the surface to their workplace
| and back during work hours. If you have 3 or more hoists
| (elevators) to take, many KMs to get to your workplace after,
| before/after shift meetings, time to change, etc. you don't get
| many productive hours from your people. I think Mponeng has at
| least experimented with having guys sleep underground close to
| the face for short periods (kinda like on-off rotations in remote
| mines) to get more effort out of them.
| scrappyjoe wrote:
| I've packed those wooden jenga blocks during a visit to
| Kusasalethu mine, which is similar to Mponeng. You can see the
| older blocks slowly collapsing under the persistent pressure of
| the hanging rock. Took about 20 minutes working with two
| miners, squatting in the 120cm high cut of rock leading up to
| the seam face. By the end of it I was soaked and exhausted.
|
| Even more crazy when you learn that the average age on a South
| African hard rock mine is approaching 50. I don't know how the
| drillers keep at it for a full 4 hour shift (2 hour shaft-
| underground train-3km hike commute to and from the main shaft
| entrance).
| jl6 wrote:
| Sounds like a great opportunity to get some telepresence robots
| down there doing the mining by remote control.
| mkl wrote:
| The entrance is at about 1560m altitude, so the mine goes way
| below sea level. It's nowhere near as deep as the Kola Superdeep
| Borehole though [1], which has been on HN a number of times [2],
| and is only a narrow bore that people can't go down. The
| temperature at the bottom of that one got to 180degC, preventing
| further drilling.
|
| [1] https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole
|
| [2]
| https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...
| cinntaile wrote:
| https://opentextbc.ca/geology/chapter/9-2-the-temperature-of...
|
| This contains some graphs (the 2nd graph is most relevant) that
| show how the temperature changes as a function of depth. It
| increases much faster than I thought.
| zeristor wrote:
| Assuming that air can equalise and the bottom of the mine is
| 2.5km below sea level, from air pressure calculations air
| pressure would be about 1/3 more, 1 1/3 atm.
|
| I had an idea to see if plants would grow faster in a denser
| atmosphere. I've found one small study, I think the air
| pressure was thought to be denser when dinosaurs were about.
| aaron695 wrote:
| loufe wrote:
| This story was posted on HN a couple months ago, there is a
| push right now for use of a somewhat novel technique to drill
| extremely deep holes, producing geothermal power anywhere on
| the planet, with several commercial ventures in their early
| phases:
|
| https://newatlas.com/energy/quaise-deep-geothermal-drilling-...
| tibbydudeza wrote:
| One of the reasons why I never studied Geology and instead did
| Computer Science.
|
| I collected rocks - had books on rocks - orientation day at the
| Geology Dept and the dude told me I am not going to be driving a
| Landrover but will be working in a mine.
|
| I looked up the deepest mine in the world - recalled a childhood
| memory of spelunking in the Cango Caves.
|
| Decision made.
| sgt wrote:
| If you look up Itchy Boots on YouTube, you could be riding a
| Honda motorcycle around the world. Probably more profitable
| than being a geologist, too.
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