The Mine Cycle

hello I'm Lila we're here at Barrett Cortez in northeastern Nevada and we're here to find out how modern gold mining works we've been granted full access here and we're going to take you around and talk to the men and women who make this mine work we chose Cortez because of its size it's got two surface operations a big processing facility and an underground mine I've never been to anywhere like this why don't you join me and we'll find out how modern gold mining really works what strikes you first here is the size and scale of this operation from the 400 ton all trucks to the massive PNH shovels it's really quite impressive you take a look into that open pit and you'll see what I mean think of the design and the engineering that go into creating something like this these people really know what they're doing and then you go thousands of feet deep into the earth to the underground operation and you realize that this is not the good old days of panning for gold in fact the gold that they mined here isn't even visible to the naked eye it's called micro gold and they mined thousands of ounces of it each year so let's begin our journey of Cortez here at the underground operations though underground mining is way more expensive to do than surface mining the extra costs associated with this method are offset by the much higher number of ounces per ton of gold retrieved mining methods vary with each underground operation and are dictated by the characteristics of the ore body itself and the most cost effective means to extract it here at Cortez the underground operation is accessed by twin declines portal din the old Cortez Gold F Canyon pit these parallel declines each measure 16 feet wide by 18 feet tall and extend for nearly two miles into the earth to access the rich gold deposit there used to haul or out and back fill in provide ventilation to the mine plus they aid in the dewatering of the Cortez Hills open pit mine which is directly overhead of where the underground mining is taking place in fact the top cut of the underground operations will eventually be the bottom bench of the surface pit but before any of this can happen it takes a highly skilled team of geologists and engineers to come up with the mining plan their plan maximizes both the safety and the profitability of this mine before we go underground let's go talk to some of them Cortez Hills on the ground is what we call cut and film mining it's an entirely mechanical method and we go through and we drive a tunnel and we backfill it with a cemented backfill which is looks a lot like the concrete that you drive on every day or your house or your office is constructed out of and once we've gone through and mined it and backfilled we then go back underneath that fill again and drive another tunnel kind of get a bit of an animation here and you can see we're at right now is we're working on one of the undercuts and you can see where we've got three levels above us that we've mined out and where we've gone back in underneath and here's another level developing here and so the orange is the access that we drive and the green is when we start mining underneath the backfill and you can see how the green bars line up with the green bars above so that we always have that cemented rock above our head and that's what we're worth the hot one way to think about it is it's essentially like playing Jenga with a vise where each one of these cuts is the individual block and the Jenga game and the vise is simply the the pressure from the rock the mine itself holding everything together and we're going through and we're knocking out individual blocks and then we're pushing another one back in and then we just work our way down through the mine that way pushing out a block and filling it back in the geology is kind of put together where it is and what's going on the engineers put together the roadmap on how we're going to get there what we're going to do and survey issues the driving directions and they actually go down and set up the control the lasers we actually have a laser this survey puts and and shows the guys where to go with the directions to mine and all together there's about 40 people at Cortez that that's their role between the geologists the engineers and surveyors you know as a technical services group our goal at the end of the day is to design the safest most economical mind possible welcome to the beginning of the minds cycle that's crazy-looking the seat behind me it's called a jumbo it's job is to drill one and 7/8 inch hole 6 to 10 feet deep into the face of the headache this used to be done by a jack leg drill and a lot of sweat and a lot of muscle now the Jumbo takes care of that it's a lot faster and a heck of a lot safer so this is a DD 422 boom drill after they come in and bolt up put up all the ground support I'll come into the heading I use a park back out by the beginning of the heading walk down and check for any substandard conditions and get all those fixed then I'll bring the Jumbo down after I paint up my grid and start to drill so we got a lot of different patterns we don't drill anything more than three foot centers so I'll go off the cut sheet it'll have left right down and up and a grade percentage up or down I'll paint all that up and then I'll come in and drill right on the cross line all the way across there inch and 7/8 holes I'll drill from six foot to ten foot and then we'll put a burn in it which could be six to nine holes it's just to start the round to initiate it this one's 25 wide with both boobs take about hour and 45 minutes to 2 hours spinning on the rock and it's hard or soft buggy or not this one's pretty soft so it'll take a little longer about two and a half hours so this is all cut and fuel in here so we got backfill up in the back and on the Left rib we're going next to the last cut and under the last level back feels really safe it's stronger than the rock itself I'm in an enclosed cab with air conditioning and keeps me out of the dust and the heat away from the elements I love the job I take a lot of pride in what I do at every round that I shoot I like to come look at it make sure it come out nice and see the kind of changes I can make I've learned a lot everywhere I've been okay so the Jumbo comes in and drills the hole in the rock and then the powder crew comes in and they put the explosives into the holes that have been drilled amazing process they do it in a pattern so whole blows and then others glow around it and then it blows down and then it blows up this way the muck trucks can come in and scoop it up and drive right out the thing you got to know about the powder room is that they're highly trained they think about safety first and then they think about safety some more let's go talk to them when you come in you time out the round it starts with the caps and they start at one and then they go up to 19 and then you start with the bird you time out the bird real slow so you can break the burn and then you break everything to it so you like sandwich it in you bring it all down to shoot the round out you break it slow you break from the middle and then you break it in from the middle in and then you hit your lifters and it fluffs up the nut pile and sets it down we load with emulsion so to set emulsion off you got to put a booster on the end of your cap then we stick it into a hose shove it in the face fill up the hole leave a 2 foot collar tie it all in with det cord then the det cord gets tied in to the icon and the icon reads to our computer system and bang so after the blast is detonated electronically from the surface when the mine is evacuated its shift-change the next phase of the underground mine cycle is ready to begin this process is referred to as the mucking and trucking cycle it was a little bit too loud to talk on camera at the time so let me now explain how this all works it's like a well choreographed dance routine the six-yard mucker scoops up the fractured or from the headings and carefully loads a fleet of 30 tonne haul trucks all within this very tight area the men and women who operate this equipment are very skilled operators who safely jockey this very large equipment around with precision so as not to damage the ventilation electrical and water systems which run over hit throughout the mine numerous headings are being worked on simultaneously providing a steady stream of or on a daily basis once loaded the trucks wind their way to the surface following miles of tunnels to the main decline as they head for the ore stockpiles let's meet some of the operators who do this on a daily basis what I'm doing right now I'm mucking out a heading mucking up at 45 35 down here and just in preparation for cycling the round after the blasts after the shots taken mucker comes in Luck's out the muck next piece of equipment in will be the boulder then the jumbo they'll drill it load it shoot it again and just keep mining our way on back into the end of the ore body a day we can load between 50 and 70 loads of muck out for shift this one's probably going to take like an hour and a half to get it mucked out and get it loaded out maybe two hours between the six-yard muckers we run an 80 30 haul truck we're hauling between 25 and 30 tons out per load we run a nine typically between six and nine trucks for rotation each trucks probably getting between 15 and 20 loads per rotation out it's a lot of muck gets hauled out plus our back feel that comes back into the headings after their mind out for our ground support so yeah it's there's a lot of material being moved it's not it's not like the old days that's pretty cool yeah this thing's pretty awesome you can it's a big mean machine you know but it little flat do the job this is your underground haul truck it's a cat ad 30 and 30 ton truck hauling the ore out take it straight up the surface and depending on whether we're hauling out or or for hauling out waste we take it to whatever designated pile up there on surface turn around and come back down to get more ore or if we run that filling we'll stop at the back drill plant and pick up some backfill from there and bring it down it might be only 15 a day or so but sometimes we can get up to 21 22 loads a day lots of going in circles a definite learning experience it's always something going on so it's a constant watching your surroundings and making sure what what your fellow coworkers are doing and it's interesting it's it's a whole new world so but fun I like it proper ground control is the key to underground mining machine behind me is called a bolter the side of this is called the rib the top is called the back now what these guys do is they come in and they put a sheet of steel mesh across the rib and then they take a high-tech bolt call the swell X bolt and they drive it into the side of the rib to hold the mesh on it then they take water that's highly pressurized and they drive it into that bolt the bolt expands and holds these bolts are so strong that they can go up to 12 times per square foot simple way of explaining it is if you took an apple and you chopped it up into chunks and you set it on table and you let go of that Apple it just fall apart if you took that Apple chopped it up into chunks but then you drove toothpicks or skewers through the Apple and set it on the table that would hold the Apple together so essentially that's very simplified that's what we're doing with our ground support we're pinning the rock together using the friction bolts creating a ring of compression so that as the stress flows through the rock it goes around the tunnel keeps the tunnel open keeps the drift open and safe for the minor shock readings kind of dual purpose does a few things for us one of the first things it does is its added ground support so is the shotcrete which is just another concrete mixture sets up it makes a hard shell that stops any of the littler stuff that might fall through the wire and come down and injure anybody the next thing that it does is it creates a seal so as you're mining through the rock and you seal it with shotcrete it keeps the rock from drying out and fracturing any further what we call air slacking and then another thing that the shotcrete does for us is it gives us a visual aid if any of the ground starts to move we can see the shotcrete crack and it gives us a an indication of what the ground is doing or if we even come back and install work on support obtaining the proper ventilation underground is truly a science unto itself maintaining a safe work environment thousands of feet below the surface is further complicated when you operate massive diesel-powered mining equipment in very confined spaces to address these issues a team of engineers and safety and health specialists design and constantly monitor the climate created deep within the earth so mining can move forward this is considered hardrock mining coal mining often they admit gases such as methane and that's why they have readers at their cutters and everything underground here though we at this mine we don't have any gases that come from the rock so our main concerns are from blasting fumes which happened at the end of shift to mitigate those and also we don't even allow the miners back underground until 30 minutes after a blast so right now all our equipment underground is diesel and we use a red dye biodiesel and that's because when it'll it emits lower DPM but the other reason why we only use diesel underground is gasoline has a lot more toxic gases that it can emit so currently with the way our ventilation is set up and our mind is set up we have twin declines the west and the east on the West there is two main fans that are capable of flowing hundreds of thousands of CFM underground that would be considered the primary ventilation so from there would be the secondary and that would be from vent raises and then to get into the levels right here connected to these the ends of the two hard lines our two 200-horsepower fans and that provides enough air to not only enter the heading safely but also to run equipment safely there are various ways to monitor one thing is the ventilation engineer we'll come down and take vent readings of headings levels main accesses and create a ventilation model on the computer and that way they can calculate differences in pressures what certain vents which would happen and what the results would be you have to have a certain amount to be able to run certain pieces of equipment once that's established what the safety and health industrial health people will do is there's actually monitors that they'll give to various miners and personnel underground that will take values of different you know DPM dust and other elemental vapors that could be encountered underground and they'll measure that against a baseline to not only monitor how the air is underground but also monitor the health of the employees like I said at the top of the show these are not the good old days of panning for gold and the horror stories that we've all heard of old-time mining techniques and worker safety are a thing of the past as well today the safety and well-being of all the employees and contractors who work at Cortez takes priority over production and it was very cool to find out that anyone even me could shut down a job if they felt it was unsafe trust me these folks definitely take safety seriously oh it's totally totally different from when I started back in the 70s safety now is so prevalent and you know with the companies where years ago it was MUC drill blasting you better make that round every day otherwise you weren't in those headings anymore they brought somebody in that could cycle them now you know we they're our main issue is is safety you know and then production follows that of course now it's all mechanized you're not having to use the jackleg losing like we did years ago it's not near as physical as what it used to be that it you know in the ventilation is by far by far superior to what it used to be I mean used to go in and you'd muck out and you couldn't even hardly see the face by the time you get done mucking out it's not that way anymore our contracts are mind wide have X amount of footage for the month that's planned out that we could achieve and everything without you know having to cut corners to achieve our goals and everybody can work safe and everything else you don't have to be on it did run from the start to the finish of the day you know so it's it's a lot more it's a lot more control than it used to be where you know you just the more you broke the more you made here we have X amount of footage per month that we need to get out and that's what we strive to do now that we know how the underground operation works let's go topside to explore the massive open pit operations at Cortez and meet the people who make it all happen welcome to the open pit operations at Cortez currently there are two very large surface operations underway the original pipeline pit complex and on the other side of the Crescent Valley is the new Cortez Hills operation each one of these open pit mines employs the same basic method of ore extraction as the underground operation drilling blasting then mucking and trucking but the size and scale to which it is carried out is really impressive they utilize some of the largest earth moving equipment in the world and move an average of 500,000 tons of material per day and similar to underground mining ground control is also very important the massive open pits are designed and constantly monitored to ensure the stability of the high walls and the safety and well-being of those who work here the way we make the high wall safe starts from the beginning before mining when we drill a couple of holes and we analyze the rock coming from those drill holes depending of the rock mass the type of structure we intersect we're going to design the outer pit basically with a certain angle a certain angle compared to the North Center certain width of the benches and height of the benches once we start the mining we're gonna install on each benches a couple of instrument for us to monitor the movement of that wall basically it's prisms so that they are mirror that a laser is going to shoot and basically depending on the distance of from the radar of that mirror the radars going to send in an alarm saying the wall is moving or not the one I have behind me is basically scanning the entire wall every 10 20 minute it gives us a movement of the high wall in real time and we can connect to it in our office and see it right away and we also walk all around the wall to make sure we visually have a monitoring so with the mind plan in place and the safety concerns addressed let's see what it takes to mine this micro gold on such a large scale welcome to the first phase of the mine cycle this is where it all begins drilling pit is designed we have geologists and modelers that take exploration drill holes and they model the ore body to figure out where the ore is spatially and it's somewhat of an estimate pretty good but when we get into mining we have to drill to blast the rock and that's on a much tighter spacing than the exploration holes so we take the cuttings from the drill holes for the blast holes and we have mass aid and sampled for the gold and do you guys have an on-site lab that you do that yes we do it on-site I believe we do somewhere in the neighborhood of 400 assays a day and it gives us much better definition of the ore body just before we mine it this is the next phase of the mining cycle we're with the blasting crew what they do is take this and turn it into this I would just suppose that using explosive it's it's all about the control and the safety and the finesse of finding the right amount of blasting material how far do you punch the the hole in we dig 40 foot benches we do on occasion we've done some odd odd number benches but generally a 40 foot bench is what we go after we have four foot of sub drill what's sub drill the drill will go out on the pattern and he knows he needs a 40 foot bench if it's high it'll tell him to jail like 46 foot hole because they're two foot high so he's gonna always have extra footage from the sub drill and then he's always going to know his location you know say he's above grade or below grade it'll tell him and he'll drill it to grade plus four foot of sub drill and that's something we use to help achieve the proper fragmentation so the show will can dig it so then get the floor out and everything goes smooth now when we see the explosion go off it doesn't go up it goes it goes across right well I'm not gonna say it never goes up that you know where does energy want to go it's going to take the path least resistance and up is generally something but we try to control that so we don't want that we want that to be completely confined in the ground so if you watch a shot that we are proud of they just roll just it'll actually just roll and there's nothing ejected out the top and that's what we want to achieve every time and that's breaking up the material right we're watching it blow the material in and it's not just the explosion that breaks there's a lot of gas and a lot of pressure in that rolling heaving process is shearing and breaking the rock to not just the actual bang that breaks the rock it's that he even roll now what is it what's the material that you use as the explosive we use a Kappa booster for initiation and then we use ANFO which is ammonium nitrate and fuel oil and at the blast pattern they are mixed but not before that when they're in transportation or storage they're always separated and then when we come out to the pattern it mixes on the truck as it's feeding the hole right on site and it's a and it's a pre described percentage of fuel that we use it mixes with it you get too much fuel or too little fuel you can have problems too so we want to you know there's like it doesn't sound like rocket science but there is a fine line to make sure everything's done right there's a lot there's a lot of detail that you have to cover so you fill the hole and then you put you put something on top of it so it doesn't blow straight up what is that stemming material that's around the hole call for stemming material if we need to but it goes in and fills the hole up all the way to the top of the collar and what that does is it gives it basically a plug so when that from the confinement the a.n the ANFO initiates and it just doesn't it doesn't eject out the top in that way it allows it to all that energy to go out and break everything there's a lot of size seismic activity that occurs when a shot goes off and you want to try to achieve the least amount of disturbance as possible and the right amount of you know you're going to have some regardless but you want to control it again here everything's about control everything's about control you know you don't wanna let it get away from you super barn shots one two and three and South gap okay now now it's you okay checking firing up yeah now watch this yeah that's amazing shots one two and three have fired yeah awesome good job and you get all the credit oh yeah all of the credit so you thought the blast was cool that we just did we're standing now in the open pit and we're over with the 400 ton trucks this is one of them right here each one of these 400 Trent trucks they get about four or five buckets dumped in them and then they go to give you an idea of the weight of the ore in that one bucket that's going right now a semi-truck that you pass on the highways the weight of three of those is in one of those buckets the guy named cauri that sitting in that cab is responsible for digging out the ore and moving it toward these 400 ton trucks the amount of soil that this bucket moves is incredible when you're in there you're right up next to it and and the sensation of it is incredible why don't we go meet Cory we should go stand in that cab let's go the technology has gotten better yeah and trucks are bigger shovels are bigger yeah so you're able to produce more tons moved at the end of the day and how many tons in a scoop we just scooped up how much um this bucket I think is uh I'm gonna say 5000 for more I remember right the bigger ones I think they're 70 plus yeah you can hit 200 loads with this shovel and we'll 12-hour shift yes it's doable big shovels think one of our guys he got 290 loads so far on that that's a lot of that's a lot of loads for the day right off that's just one digging and I'm sure for you guys it's not about how fast you go but how how safe and how effective and how efficiently you scoop yeah I know you're getting all these loads and then towards the end you hurt somebody or damage right with a nice counter Patel yeah right yeah a good save shift and for me it's it's it's not going fast it's just being efficient right so if I'm feeling this bucket every time I don't have to go fast and right you don't have to be speed yeah fill the bucket every time and you're being efficient the just the sheer volume of or to the yeah John yeah I'll just pretend and it blew my mind how much is made and I understood fairly quickly why the investment because the return on it is amazing that's why that's where the computers come in for that's the part I like because if you need to make sure that or goes to the right area right everything right and with the GC the assignments it's a it's a for-sure thing that that that or gets to the right spot as you can imagine the proper training of the employees who operate this huge earth-moving equipment is vital to the safety and success of this operation when you have a three-story tall shovel feeding a two-story high truck everyone needs to be on the same page and know exactly what they're doing we were invited into one of the simulators used to train the truck drivers who operate this equipment in all kinds of weather and conditions so this is actually you're you're in constant physical contact even though even though it doesn't feel like you're moving very quickly you have to be really physically aware of what you're doing correct about a three-story house yeah yeah okay so what's going on with me now so as we get to this intersection uh-huh we'll make a right we'll go up to that show okay this way a little bit keep going and we want to now make return we want to put this little are right on our bedroom see that logo so let's go ahead and put it in reverse and that's back and then as we back up we'll try to get this bed rail right on that arm they do that right for you at the home three times to go back when we're production you best the correct of course a whole but in production you don't have to go ahead an backwards it tells me in Reverse what's in once again it's going to take a little bit to get rollin tightly roll and stay after control to this top notch good angle your your bedrail over to them that's the right my dad would stop right so we drifted a little bit listen pull up just a hair we want this so we're looking straight down the button over there look at that that's pretty good all right so is your position under the show oh okay that's actually very very good last time you do sites tours and take them out and four will do walk arounds we got training grounds out there that we like to take them to the training grounds let's let them drive around out of production and then at least a week of stuff inside the simulator Wow things inside the simulator will be an introduction just kind of what you just got yeah just to make sure they feel okay here sometimes this makes people a little bit queasy yeah and then we'll go right straight to spotting at the shovel at the dump and then emergency procedures right which is kind of our final test right we just set em on fire at time and time and time beginning what full picture now you're on fire ah thank you so much really appreciate it that was great fun so what does it take to operate one of these supersize trucks it takes women and men with the right attitude and skill set to respect the capabilities of their equipment and each other this deep-rooted safety culture in place at these facilities is paramount to ensure everyone goes home safe and healthy every day well every day is I want to be better than the next guy and and and and that keeps a lot I was going oh he just made that load I got to get in and get that load but loans you do it safe right is it's not a recent thing but it's a keeping a thing you know we call ourselves the Thundercats the Rolling Thunder cash you know and we be rolling but we stay in safe I think that the training got a lot to do with it yeah they can see what you're gonna be in your training right and if you keep something up then it's an issue then they take it just by tell what's going to happen by the habits that you have and messing up you know you can track it in your training you develop another aspect of driving you take on the seriousness you take on a sense of caring and everything like that because that's what they put into their training I've never seen safety like they have here I've never seen it because they have you to take it home yes sir I like to safety culture because every morning they act the anybody have a safety share you know and that's that's really awesome and sometime I'd say some things and when something happens you put it down on your FLRA card and things like that and you can talk it over with with anyone and safety and anything like that they give you so many hours of safety and things about every little thing and that that you can think of because it's needed because once you start sliding and didn't act about it then you out of control you're no longer in control but when you're in control is when you're head of it and you want to be ahead of those things you know and that's that's what I've learned in driving being used to driving that that you have to do you have to stay in control so now that we understand how they mind here let's step back and take a look at why they mine here once again the goal throughout much of Northern Nevada is micro goal that is not even visible to the naked eye so how do they know where to find it to answer this question we spoke with one of the many geologists on staff whose job it is to not only discover new resources but maximize the production from those being mined so we're standing almost at the bottom of a pit that was mined right this isn't active any longer correct yeah we just finished this a couple months ago and how long were people working down here on this pit started about in 2008 we're looking at about five or seven years here yep it'll be active again couple more probably next year's the next phase comes down could you tell me how this was formed what kind of rock were looking at oh yeah alright so very long story of course and I'll try and sum it up so basically all the rocks you're seeing here the background excluding the the white ones that you see going up those were all formed at a continental slope under the ocean so there are primarily lime stones siltstones sometimes you find some fossils of ancient life-forms that lived in this ocean and those were all formed and then they were folded and faulted through a series of mountain building events and then later we had these much younger rocks which are the white ones and those are a type of magma that actually came up and squirted through fractures or faults in the rocks and they make our dikes that you see on the walls when you are looking for gold and in the mountain what do you look for what kind of a kind of formations are you looking for or colors I mean how do you find it well that's really tricky actually and that's kind of a million-dollar question a lot of times do you you know you do a lot of drill testing you do some chemical tests with the soil that's more the exploration area and then once you actually get into it it's a matter of drill testing and a saying and then doing a geologic model to try and find any trends in the deposit because each deposits a little bit different so there's no set key of how to find gold for us our main deposit in this pit is actually seen in this wall and it's the Brecher pipe and so that was something that once they found it it was a matter of actually just tracing where that fell and that was kind of our high-grade body that we could follow and I mean to set the conditions right for this type of deposit it takes billions of years and many different episodes and no one's really sure the exact combination so we had starting about a billion years ago some really old structures and faults just happen to set up condition this area to then be a good candidate for holding gold and Plus you know folding and more faulting and you have to have the right rocks to trap the fluids in and concentrate the gold so it's it's a long and complicated process that we're still you know studying it every day trying to figure out why exactly this spot do we have gold now I have a question the we were talking about veins of gold that's a different thing than what we see here right yeah that's that's not something you're going to see in this mine so all the gold in this mine is disseminated gold unfortunately so it's all distributed within actual rocks themselves and so you actually have to dissolve the rocks to get the gold out in the Beretta body itself I mean you can get upwards we had a very small hit of 8 ounces per ton so but that's really unusual so a lot of times you get a lot lower than that you know couple ounces per gold and that's still that's considered pretty high-grade for an open pit with the ore now mined from both the underground operation and the larger open pits the process of retrieving the micro gold can begin at Cortez this process is dictated by the ounces per tonne contained in the ore they mined the lower grade ore is hauled directly to a heap leach pad facility this process works by stacking the ore on an engineered pad that is lined with the thick impermeable plastic liner a dilute cyanide solution is then applied to the ore by a series of drip lines as the cyanide trickles down through the material it dissolves the gold and carries it to a lined collection pond from here it's pumped through a series of carbon columns that captures the gold as it bonds to the carbon for further processing for the higher grade or they mine the process is much more complex now we're at the crusher this is where the open pit operation ends and the processing begins over here stockpiles of or they're selectively graded and then fed into the crusher let's go inside and see how it all works the crusher circuit at Cortez is really amazing this huge gyro can reduce a large boulder down to football sized rocks in a matter of seconds and this entire facility is computer controlled by just one Operator the selection of the stockpiled or are being fed into the crusher is based upon what grade and/or type is being called for by the mill for processing down below this is the conveyor the crusher crushes the ore and drops it onto that and takes it seven miles across the valley this is an amazing engineering feat that can take a thousand tonnes of ore across that Valley in one hour seven miles later and about an hour the ore is traveled all the way across the valley and so of we behind me is the mill and that's where the ore goes next I'm standing here with less less what do you do here well I'm a male supervisor here and behind us is our final transfer tower from across the valley the order drops into there onto our stacker belt travels to our course or crushed ore stockpile and from there it feeds out the bottom on apron feeders to our number three belt which you see going into the mill I see so what happens to the or after it goes into the mill it runs into a sag mill well a sag mill a sag mill is a semi autonomous grind yeah a semi autonomous grind I love it we have five inch steel balls inside the sag mill that break the ore down and release it about three-inch - and from there it goes into our ball mill a secondary mill and when it comes out of there it's about 70 percent passing 200 mesh it's a very fine just a fine powder and it goes into a grain thickener after that and we lower this the slurry the heavies is the ore to the bottom and your clear water comes to the top I see from there we separate it the slurry goes out the bottom and comes up to our CIL tanks which you'll see here we add cyanide in our search tank to start the reaction of dissolving gold right and from there goes into our CIL tanks carbon and leach and there's carbon in there and the gold gets absorbed into the carbon you put the gold into the solution and then you run the solution through carbon what how does the carbon grab it and what's the carbon on I I want to see it in my mind well if you if you've seen the carbon in a microscope it looks like a sponge I'll carry porous right and with gold dissolve into solution it gets absorbed into the pores of carbon so as it goes through the CIL tanks the first three tanks we've picked up almost all the gold into into carbon and then where does the carbon go with that's loaded with the gold the carbon gets if you look at the tanks we rotate our carbon gets moved up the train as it goes or Baron carbon is in the lower train or preg carbon is in the higher train we pull the carbon out pump it out over a screen and separate it from the slurry right from there it goes down into our Aleutian circuit okay what's an Aleutian circuit our Aleutian circuit is our strip circuit uh-huh from there we'll put the carbon in strip vessels and we heat the vessels up with a Barren solution to about 275 degrees at 80 psi and it it presses the gold out of the carbon into it back into a solution nice and where does the gold go after that the solution goes into a pregnant in our refinery from there we pump it through electrowinning cells electric winning cells are basically a positive negative charge the gold gets collected onto the anodes and from there it's a sludge Gold sludge from there we press it down to a cake and melt it down to gold now you say cyanide which for for me and people who don't know about how chemicals are used and and and how you use them so they're not toxic that that's like cyanide what what can you tell us about that process so so we know that you're safe and that we're safe well cyanide can be deadly and you have to respect it we run about a quarter pound per ton of solution of cyanide to put that in perspective you'd have to drink about three gallons of the solution to really see any effects I don't think it can hurt you that way right but we do have it in a higher concentrate around here yeah absolutely you have to respect it we have a cyanide code now here that barrack adheres to its an international code and they're very strict on on your uses of cyanide how you handle cyanide and how it looks throughout the industry signage warnings the way everything about cyanide is handled through that code and we're very proud that we've we've accomplished that passing the cyanide code terrific a gold pour is just about ready to happen let's go check out the final step in the gold extraction process the furnace here in the Cortes refinery is a hot one it's cooking this gold to 2,000 degrees Fahrenheit to remove any impurities once this is completed the unwanted slag is removed from the top of the molten gold and then they take a sample for a saying purposes the molten gold is poured into bars and may contain about 90 to 94 percent gold and three to six percent silver the bars are then cooled down and are sandblasted to remove the slag the bars are then assigned a number and then they're weighed and logged the gold bars are now ready for storage in the safe until they're transported off site for further refining down to 99.99% pure gold the refinery at the Barrett Cortes gold mine pours an average total of 1 million ounces of gold per year so after all the hard work we've seen the engineering the digging the hauling the crushing the refining this is the final product this is called a door a bar and it's about 700 ounces of gold it weighs it weighs about 65 pounds you're looking at about 6 million dollars worth of gold right here but before we wrap up the show we have one question left unanswered what do they do with all the dirt they move that wasn't or that's where the environmental department jumps in their role in the world of modern mining is of great importance since the protection of the land air and water where mining takes place is more important than the gold they produce everything from reclamation to the dewatering activities that take place are carefully planned and monitored the engineers design all of the waste dumps which is what we're standing on right now and we try to contour the waste rock dumps in a native topography so that it looks natural right right now it doesn't look natural because we're dumping on it but after they're done dumping we come back in with growth media which leaves media it can either be a loom that's harvested during the mining process or it could be topsoil it was scraped before we started digging we spread that and then we plant over it and do you shoot it with fertilizer or water or anything or does it usually do okay without all of that it depends some sometimes we hydro seed which you know we mix the seed and the mulch and spray it on with water or we a lot of what we do is broadcast and Harrow and it's especially useful on the waste drug dumps because they're a lot steeper and what does that mean so we'll come out and we'll rip the ground and we'll broadcast the seed and then we'll drag over it to get that seed soil contact we do concurrent reclamation so we reclaim areas as they are finished a lot of the waste drugs done through reclaim within a week yeah after it's all said and done usually mine ops gets the growth media on the surface and then the seeding and ripping usually they can get done in about a week it helps with soil stability and it keeps noxious weeds out of the area also and you know benefits wildlife and insects and all the critters out here this has been an amazing trip the best thing about this week has been the people I've met here at Cortez there's absolutely no doubt they are friendly they are professional they are funny they are concerned with my safety they were knocked out by how interested I was and what they were doing and I was knocked out by the scope and the enormity of what they were doing but the absolute humanity and safety that went into everything that happened on the ground there I had a great week you

Channel: nevadamining

Views: 193,200

Rating: 4.7039323 out of 5

Keywords: Gold mining, Cortez mine, Barrick North America, Nevada mINING, Nevada mining association, Modern Mining, Mining Cycle, Mining Phases, Active gold mine, Modern Gold Mining, Nevada Mining Industry, How gold is mined, What is mining?, NvMA, NV Mining, Reclamation, Mine Blast, Mine Blasts

Id: nmAVtQ7MU4Y

Length: 53min 44sec (3224 seconds)

Published: Mon Apr 21 2014