A lot of the discussion on the board here seems to center on the really big iron--dozers, excavators, haul trucks, that are used in mining operations. I've spent most of my career doing residential work, with some time doing utilities like water and sewer. I know mining involves moving a lot of material, but I don't really have a handle on what the nuts and bolts of it are. Does anybody want to take a shot at writing a description of what goes on in a mine operation, from the time the first bladeful of dirt is moved, to the time the last piece of equipment moves on to the next site? I'm sure it would be interesting...
I'll second this.
Me too. Don't know much about it.
A real real quick one would be, Dozer,pans scrape the durt off, haul it away (pry to landscapers, houses). Then Usually rock is blasted. Loader or excavator loads it on a haul truck. Haul truck runs it to a crusher. (Crusher is just one plate"bouncing" up and down, crushes rock, it goes trhough screans depending on sizes goes down different conveyors to different piles where a loader laods it onto a truck and off to the job. Some stone is washed. Then usually stuff is backfilled into the hole (depending on epa, city etc). in the past (and still some of it), shingles, rail road ties (again no no but it is still done), broken up concrete, trees,asphalt etc is dumped back in the hole.
I watched a show about open pit mining on the history channel and before anydirt gets moved there can be 10-15 years of planning, testing, and permiting.
Although my mining experience is somewhat limited ( one in particular is a long and funny story ) I believe that most mines ( well , open pit mines ) operate somewhat the same . One of the largest mining projects in my neck of the woods is the mining for oil in the ' tar sands ' . Basically , it's a huge ( second only to the Saudi's reserve ) deposit of oil that blended in with sand that failed to be ' capped ' , meaning that instead of the oil pooling under a great layer of material deep in the earth , it instead mixed with the sand and stayed somewhat close to the surface . The way they extract the oil or work this deposit would be the same as for how they extract other minerals like coal , or even gravel . After all the studies are done measuring things like quality , quantity , locations , etc , engineers decide the best way to tackle the seam , and begin by removing the top layers of materials referred to as overburden . In the case of the oil sands , everything from scrapers to large shovels and trucks are used to strip a area of overburden , and when enough of a area is deemed ready , they load and haul the tar sands using some of the biggest shovels and trucks money can buy . The trucks haul it to a dump area that usually consists of a large chute that goes directly to a breaker or grinding tub , like those found in gravel pits used to make gravel products , then the broken up material is conveyored to the oil processing plant , where the oil is seperated from the sand and then off to the refinery to be more thoroughly processed . When a seam or area is exhausted of useable material , the overburden is either dozed or hauled back in and the land is reclaimed , meaning the ' crappier ' material is dumped in first , followed by the organics like loam , on top so as to replant tress or vegitation . Now , this is a rough and basic explanation of the open pit mining technique used for the Tar sands and although it seems very simplistic , because of the scale of the projects it's actually a more complex and difficult thing to do , especially when taking into consideration the extreme temperature fluxuations of the zone the area is located in ( from plus 30 degree celcius in the summer to minus 40 or even 50 degrees below zero in the winters ) , and the abrasiveness of the sands itself , etc . I guess to some degree , its done in the same fashion as how your local gravel pit is mined , just on a larger scale . Hope this helps , or even makes sense , lol . Rob
Thanks for the info Blademan. I have always wondered exactly what was an tar sands operation. (I thought it had something to do with making asphalt:beatsme ) From what guys have said on this forum about these operations, it seems to be a pretty harsh place for equipment and operators.
I'm guessing that digger was thinking about large ore mines that we've seen the huge mining equipment pics from, but I can reference the quarry I use for aggregate, the entire operation is visible from where I get loaded. The operation is very similar to what thejdman04 described. This quarry has been in operation for nearly 100 years so most of the topsoil has already been scraped off. Starting at the rim, they drill the rock in steps to the bottom of the pit. They hire an outside firm to do this plus the blasting. They use the fertilizer/fuel oil type blasting agent and mix it going in to the holes. Once the rock is shot, they use an old Cat 992 with a concave rock bucket to load Euclid quarry trucks. I think they've got 16V71s in them, they sure do scream! It's quite a climb out of the pit to where the crusher is, they dump into the crusher. I'm about 10 to 12 miles from the quarry and if the wind is right I can hear those trucks climbing the hill! At the crusher, there is a stationary excavator with a hammer on it to break up the rock that's too big for the crusher. After it goes through the crusher, various conveyors take the stone to piles depending on the size. Some goes through a second crusher to get reduced further. This quarry has both an asphalt plant and concrete plant on premises. There's a Michigan 275 loader that keeps both plants fed and a second antique 275 that loads customer trucks. I don't know what the plans are for when the rock is exhausted, but I suspect a portion of the quarry will become a lake. There are pumps running constantly to keep the pit dry.
What specifically brought the question to mind was the mention of using a certain dozer as a "tailings dozer", and I realized that I wasn't well enough aquianted with what goes on to know exactly what that meant. The kind of things I was wondering about are how the whole operation is managed logistically--do they push up a big pile of material in one spot and then push it back once the product has been removed, or do they start at point A and work toward point B, depositing the overburden behind them as they go? How far do they go with the dozers before they start with the shovels or loaders? Do the trucks haul overburden around, or are they only used for the product? I imagine with coal or ore mining, or quarrying, they're simply sending most of it offsite, but with oilsands they've probably got to put the "sand" part back, right? Those are the sorts of things I was wondering about.
The coal operations I have been involved in 'simply' moved Mountain A to a new location. That is, the rock was shot to reveal the coal seam, that rock was then hauled out via rigid frame truck (same as used for the coal) to a tailings pile, which was then worked via dozer into a rough mountain shape. Once the engineers deemed it too large, a new pile was started. The material was not moved back to it's original position, but these mines operated several pits at the same time so it wasn't exactly possible. Essentially, that Mountain A became Mountain B; same material (minus coal), different location.
Basically around here (the company I work for) the pit is shaped lieka U, the bottom of the U is where we are done quarried. The bottom of the U is a deep hole, and we are always working towards the upper part of the u going in a "northern direction. There is high ground (normal grade surrounding the pit, and then a hole where material has been removed. At our pit you can drive full circle around the pit on the high ground. What we do is when trucks (usually dump trucks or semis) come in w/fill(clay, old ashpalt, railroad tiles if no ones looking and we can get it covered up quickly:ban , will dump as close to the edge as possible w/o backing over the edge, dumping the fill on the high ground and then when somone gets a chance will take the loader, or dozer and go up and push the fill over the edge filling in the hole. Hope that makes sense.
in the pit where i work overburden is stripped with loaders and our dozer. (overburden being black dirt and material we would later screen for fill sand.) we scrape the black dirt and pile it first, we dont screen the black dirt from our pit because we will use it to reclaim our pit after mining is completed. after stripping is finished we will conduct tests to see what is in the bank, we do this by drilling the top of the bank, and visually looking at the bank once we have opened up the face with a loader. once we know what the bank will yeild we pull in the correct plant either a screener or a crusher, depending on the material we need to process. this summary is pretty vague but i hope it helps. - komatsukid.
OK, where to start? Every operation is different to some degree or another. I work in the oilsands and that's where most of my mining experience lies. For us, when we have mined and processed the sand to get the bitumen out, the sand is pumped through pipelines out to the old pits or large dykes that have been built to contain the sand...or "Tailings". The specially modified dozers we use work in the slurry that comes out of the pipelines. The slurry is very abrasive and full of clay and silt as well as the sand. If we don't work the sand and such, it forms soft pockets and is useless as land in the long run. When we work it, it dries up, settles,and we have useable land again. Since the dozers run in slop and sink frequently...we sunk two today...actually, the same one twice....we have them modified so they will last longer and run a bit more reliably. We basically do as you said and move the overburden to the area we have just mined out right behind us. As I mentioned, the sand gets deposited elsewhere since it can't be poured into a pit until the mining is done...or we would have to build a very large and expensive containment dam. Our trucks are used to haul ore or overburden as they are needed. For us, as long as the ground is good enough, we haul everything by truck. Dozers are very expensive to run up here since the oilsand is so abrasive, plus we move all of the overburden too far to push with dozers. If you have any questions, feel free to ask, I'd be more than happy to answer. Brian
Kennecott Utah Copper ( www.kennecott.com ) will reopen their mine for tours in another month or so. When they do, I'll definitely be up there to take some pictures to post. I'll make sure to take pictures that show the steps of their mining process from beginning to end. And it's just cool to be able to look down into a pit 2 1/2 miles across and 1 mile deep and watch a couple dozen 797B's and 122 793B's hauling rock to the crusher.
Kalgoorlie Consolidated Gold Mines, operator of the Kalgoorlie Super Pit, have an excellent website that will provide more info, with top-class enlightening pics, than I could explain here in 2000 words. The site outlines gold production overview, the mining process, mineral processing, underground mining .. as well as providing a photo library, a virtual mine tour with 270° views, plus 4 top-class blasting videos. If the videos open in full screen and are blurry, use 'ALT +2' buttons to shrink the pic, and 'ALT +3' to return to full size. http://www1.superpit.com.au/pages/prod_overview.asp The rock in the Super Pit is Hard, with a capital 'H' .. and abrasive. This stuff is either greenstone, basalt or diorite, and new ripper tips and excavator teeth last around 2-4 hours in the rock, if not properly blasted. Some of this rock is so dense, it runs around 2.5 tonnes to the cu metre, so you won't see any oversize buckets or dump truck bodies in use ..
Excellent site Oz. :drinkup Thanks
With regard to the "tailings dozer" question .. tailings are the finely ground residue of the mining grinding process, and pose a headache for mining companies, as they have to be made environmentally acceptable .. rehabilitated is the word. Thus, tailings rehab work entails the specific use of a dedicated dozer. Tailings dams commence life as a cleared area, well away from any current mining operations, and potential future ore bodies (the ground is 'sterilised' .. i.e. - checked for ore underneath it, by drilling prior to use as tailings dam site) .. then four wide walls are constructed from waste rock, to contain the tailings that are pumped in via a tailings slurry pipeline. The water that drains from the slurry is recovered and pumped back to the mine for re-use. As the tailings reach the wall height, the wall is increased in height, to keep the tailings slurry contained. Once the tailings dump is finished (either by the ore being mined out, or height restriction reached - height restrictions are to avoid visual pollution) .. the tailings are allowed to dry out, then they are covered with waste rock, and the sides of the dump are sometimes pushed down, to about a 25° angle .. and the whole lot covered with topsoil and then seeded with native vegetation. The same is done to waste dumps, for rehabilitation. The economics are not there, to return all the tailings and waste rock to the hole they came from .. so the next best solution is merely to make the dumps visually acceptable by smoothing off, and re-vegetating. In the case of many mines, where sulphides are present in the waste rock and tailings, it is also desirable to contain the sulphides to prevent acid run-off destroying surrounding vegetation. Here is a website that shows minesite and tailings rehab work .. http://www.vetiver.org/AUS_mining.pdf
Attached is some information about the coal strip mining project near where I live. The drag line is dubbed "lady Marion" and when driving to Minto you can see this massive machine from the road. The coal mined is used to run the power station near by http://www.village.minto.nb.ca/NBindustries.html
We have our mining license. We just use for our shale and top soil pit.
cool video
My mining experience I've only been in one mine...it was in Red Lake, Ontario and they mine gold there. It was really interesting how they actually get the gold. Seems that a vein of gold is shaped kinda like a lightening bolt through the earth. They mine around and down to the bottom of this vein and then start mining into the area that has the gold. As they take out an area containing the gold ore, the area is then filled back with a concrete and rock solution. After it hardens they start on the next section. Basically they take all the areas out in sections and fill them back in as they go. They work from the bottom to the top. When they are done there are no open cavities in the earth and they have removed 100% of the gold. We were down approximately 6000 feet and they were still going deeper. Its hard to comprehend just how big the mine really was. While the process was going on at 6000 feet down, the same process was happening at around 4000 feet down. Each level in the mine was separated by approximately 120 feet of earth and some levels were connected by haul roads while you had to get back on the elevator to get to other levels. Hard to believe that there were as many as 300 miles of haul roads and they were created by blasting out about 15 feet of material at a time. I have a few pictures posted under “Weird Grader Applicationsâ€.