Mine Water Management: Treatment, Tracer Tests, and Geochemistry

[00:14:55]foreign thank you all right welcome everybody thank you for joining us for this Geo talk especially those people in the room I know it's a busy time of the year with your first draft it's due for honors and many people in the field there's a great audience online so thank you very much for joining us uh for two special guests from China University of Technology and they're standing behind me so Professor Chris blockersdorfer and Elka we'll go over thank you for joining us um and I'm not going to take a lot of time reading these very extensive biography which is very impressive um you can check that out on the on the mail there when you've got it but Professor is Versace research chair in acid mine water treatment at tswana University of Technology the president of the international mine Waters Association and a member of the Academy of Sciences in South Africa and he has 33 years of experience in hydrogeology mind water geochemistry in related fields but has also worked in many other applied geology fields and there's a long list that I weren't that I won't mention here um he got his PhD in Germany he was debilitated in Germany as well and has got many projects all over the world and a large research team and has over I think 200 papers that's a very impressive record so thank you for joining us and then his PhD student [Music] interesting he did a bachelor's degree in Geo ecology that might be something that some students in the audience are interested in finding more about and then went on to do a masters in hydrogeology and Engineering geology in Freiburg in Germany and now she's obviously working in the saichi chair for mine water specialization together with Chris so thank you both for joining us and there is an incredible range of very interesting things on this table so hopefully everyone on Zoom can see that and um we'll get started over to you guys thank you okay thank you very much for your introduction thank you very much for being here in the audience thank you very much here's the camera thank you very much for for being online with us uh for those who are online I'm sorry I cannot directly participate in the experiments that we prepared for you because we want to make mine water I mean everyone knows that we have mind water around us but how do we make mine water that's interesting deny this thing tonight yeah perfect so that's what we are going to do here so how can I we brought a couple of things that we want to show you and we will start with making line water before we start the presentation what I brought for you here and I will pass that around is where everything starts with our mind water problems and that is a very beautiful mineral and that mineral is called pyrite I will just leave it with Pyrite you know there are three that's pyrite that's smarter side and protide always when I say pyrite I mean the three Oak so not just one of them so the mineralogists here I'm sorry I know they are different but to make it simple we'll do it like that and that's from the which water sand so most of them we see it but let's go Bridge that's very gold Rich here um that's where we start but I also brought you just one uh pyrite Crystal here you know that's uh pyrite I won't let it go around the last time when I did it I had to search for it someone wanted someone wanted to take it with her though not really um so when when you expose that to oxygen what happens it starts to weather and when it starts to weather it means that a lot of chemical reactions that I will show you a little bit later will occur and after a couple of weeks months or years we have something like that it disintegrates yeah that's what you can hear here and one of those disintegrating products that is coming from that weathering is what we call efflorescent salts and these efflorescent salts they are storing for us the asset which then causes low PH values and acidity and what we are doing now is we will use just normal tap water that I brought from uh Pretoria and one of you can measure the pH rase and then we will see what is the pH of the water entry and those who are from Pretoria I know we have two different Waters in Pretoria uh the hydrogeologists here this is the mind this is the Mind water this is the water from where the campus is that means it comes from the dolomite which means we should have a pH of Alaska sorry online audience that I'm always away so we verify that this has a pH of seven with these pH sticks here that's what we are expecting and um I know I hope no one from health and safety CI should use gloves now but let's make it simple so I have here those efflorescent salts in uh in that container and what I will simply do is the American speed um so what we will simply do is I will take a little bit of those efflorescent salts and one of you will just put them into brass full name um when that happens in nature then we get something like that you see here this is really acidic mine water I don't call it acid mine drainage because when I took that sample when we took that sample it was not acid but it's acidic two different things a lot of people don't see the difference and if you look to the screen here on the left side and the audience on the video looks to that that sample that I have here that orange sample was taken exactly here and you see that water here is crystal clear and then after a couple of weeks when the iron starts to oxidize you get that huh so what we are working about in our team is on one side that water that comes out crystal clear as you can see it here but then also the water that gets reddish after a while and that's also a trick no it's not a trick It's Tricky when we're working with mine water we have to take a lot of parameters immediately in the field when we take it a couple of weeks later the water is not the same anymore and a lot of people don't know that they they are sending the cheapest the cheapest employee that they have into the field to take a water sample then it stands for a couple of days somewhere in the lab then they analyze that and the results have nothing to do with the reality anymore don't send your cheapest employees into the field send those into the field who know what they are doing okay let's see Peter what you did hello here a small Webster let's stir it first so we're just increasing the the chemical reaction speed a little bit here uh in the stera okay that's done and now I need someone okay [Music] so the net of the department I think head of department is working forward here or is that correct head of school sorry um she's now going to measure the pH for us and if I did everything correctly we should now have acid mine drainage put it on okay so what you could see so we have a pH of five to five point five now uh it always depends a little bit on how how much of the accurate insults goes in the into that container so you saw that with those efflorescent salts that come from the pyrite weather right we make our acidic mine water I'm saying acidic mine water because it's not acid mine drainage yet why is it not necess migraines you will see in a couple of slides okay so let's start with the presentation so two years ago three years ago just before Corona started okay a colleague of us and and I we we asked in three German mining areas what do you think what is mind water and what you can see on the workload behind you is of course water ground water that were the words that we had most often that we also had toxic uh the water will be will there be forever it's a problem it pollutes the environment we need to pump it um it will cause damage it will cause items so these are words that you heard from the people so it's not different from what we you know drainage most of the news is bad we want to bring the good news because it's much better of course it's our work it gives us money how do we see mine water we see mine what a little bit different we see it uh in different costs we say something that we do research not to mind what the Tracer test this is here in the West Front you see the water is coming up Crystal Clear after a couple of days after a couple of meters it looks like that this one here is a place that I'm not allowed to speak about because oceans are every kind it has a pH of two so very low PH a couple of hundred milligrams of liters a couple of milligrams 100 milligrams per liter of iron sulfate in the thousands so that's what you typically would call acid mind range this one here is in pumalanga that is in Sabi sabi is one of the only places that I know in South Africa that gets drinking water from mine water this is mine water it's coming from a gold mine so gold mine water does not always mean that it's highly polluted it can also be drinking foreign this one is in Germany now it looks very bad but the water quality is not that bad it's directly flowing into a stream where they are fishing Edgar what is that Ah that's in uh Carolina now that's carrot that's Puma langa it is Carolina yeah so that's where the councils for geoscience constructed uh passive mine water treatment system now so the water here is quite bad but it comes out again very nice color so that's how we see mine water a wide range of colors a wide range of chemical compositions so from pH of two in that case to a pH of 7.5 in that case this one also in Germany has a pH of 7.5 so wide range of pH values we'll come to the th values a little bit later no what do we consider when we speak about wine water and some of you might think I in my future career will never have to do something with mine water well do you know that we need to know something about the geochemistry so if you're doing something with uh geochemistry now it does not mean that you are not ending up in mind water one day we need um microbiologists because they help us to understand the chemical reactions that are catalyzed by microorganisms we need to speak about mind water treatment that's a book that you see here in front of me that's the latest book about mine water treatment that I wrote we need to understand something about the hydrodynamics so if you are studying physics for example if you're interested in physics these are the people that understand hydrodynamics hydrogeologists also understand hydrodynamics but we need to understand also the effects of the Mind water so effects we mean when you're a normal person living directly near a mine and you are affected in any way by mine water these people we also have to address we also have to speak to them so this is the broad range of subjects we need to consider in mind water research now let's clarify a couple of terms what is mind water so you can read much faster than I can speak so while you're reading it I can go ahead speaking we have a definition for wind water you probably asked yourself why did I not use a single time well I used it twice the term AMD or acid mind drainage that will come shortly our team does not use that word because it has a clear definition and in most cases we don't have asset mind values so our team uses another word we will come to that so mind water is usually used without saying anything about the pH value it's just a general term for everything and I wished a lot more people in in this country would use just the normal term mining water yeah instead of saying something that has a clear definition which is wrong when they use it in many cases so our team always writes now mining influenced water this is a word that was introduced 1997 it's clearly defined what it means it's nearly every water that somehow was in contact with mining mining influenced water this is the proper word here in South Africa you very often read mining impacted water that's wrong it has not been defined that child yeah we should make sure that we are using terminology that has clearly been defined if you want to come up with something new Define it for us so that we know what it is and now we come to that one acid mine drainage an asset mind range has also a clear definition and as the Mind range is only mine water with a pH below 5.6 so that means the mine water that we made here now because it's 5.5 to 6 so it could be acid mind drainage but we don't know it uh when mine water has a pH above 5.6 it's not acid mine drainage anymore so for example we have the acid mine drainage water treatment plant in the East rank the pH of the water is 6.5 whereas the acid mine drainage in the whole wheat Waters Trend we don't have acid mine drainage anymore huh but people speak everywhere that has nine drainage is polluting the environment from there there is no acid mine drainage and therefore acid Monitor and it cannot pollute the environment that acid migraine at that mind range there it's acidic but that's something completely different you know acidity means protons does the acid plus metal acidity that comes when the metals precipitate protons are released and when the protons are released you're producing uh acid and it comes from the humic acids and if you add all the three together that water is acidic but it's not acid mine drainage so when I'm confusing you here at the beginning and you're hearing that the first time that important is that we are using correct terminology and it's not my terminology that has been defined Years Ago by Specialists that are working with mine water regularly curved Nordstrom for example he wrote a very nice paper about that when the peach is above eight we speak about alkaline mine water and when it's between roughly six and eight it's circum neutral so the mine water in the wheat water surround and all the three basins when it discharges that's the proper term when it discharges not decants decant is when I pull that into something now that not when something is free flowing out better discharge so when the water discharges it's circum neutral so we have Circle neutral line water which is easy to treat now there's absolutely no problem okay that was a little bit about terminology now we oh there's someone in the chat and I heard that I shall try to answer uh in the chat oh yeah we can answer that later can't we that question but yes of course everything that LK and I or our team is doing is always freely available we are coming from a group of people that think we are not patenting anything we are tied by the state and we give it back to the people that pay us therefore no patenting everything can be freely used okay when you said I need to do that so how does the Mind water evolve we have an underground Mark so the miners just decided to get bankrupt the miners decided that all the or has been taken out from the mine and um then we had just the empty Mark so they stopped pumping now and Peter just said that his son has to pump a lot of water in his mind in Honduras that he said in Honduras so if he stops running those pumps that's what we see in the with Waters Rand now or a couple of years ago then the water will come up then we have a stage where it looks like that the water that is flowing into the mind this normal groundwater that's usually not contaminated only when it gets into contact with those efflorescent salts yeah then it becomes acidic as we added here find this groundwater which is in case it's not contaminated unless it comes from a contaminated stream here of course that's something different and that at one state the mind is completely flooded that means water flooded the Mind completely and then it's discharging somewhere you know as we saw it I think it was in August 2008 in in the Westland and the autograph of how it would look like um here I climbed down in that mine your internet connection is unstable that's nice um so here I climbed down to the water level in that mine that mine was 100 meters deep because the discharge added was um um but I think 1.1 kilometers away from there and here you can see that bluish Crystal Clear Market pH of that water was 7.5 but we cannot drink it for two reasons it has elevated arsenic concentrations and asbestos so we don't want to drink that water foreign process but in that case we can see how the water is filling up and then at the end we have a mining Lake in many many cases leaflets really have acid mine drainage you see that in mpumalanga in the open pit mines and when you look to Google Map or Google Earth you see all those red dots there from the acid mine drain and also a nice red color as we would see it here but now let's go to the asset generation process how do we start to make mine water that's how we did it manually but how does Earth do it how does nature do it everything starts with these two really beautiful looking minerals the upper one here is the marker side that's fvs2 so one iron to sulfur and that one is the pyrite it's exactly the same one iron two sulfur just two different Crystal systems and what happens next is we let that react with water with oxygen and someone who helps us in the process water oxygen and then microorganisms the microorganism that we see here is a series and for those of you who are working in Mayan water theobacillus steel oxidants does not exist anymore it has been renamed in 2000 but I still read it in Publications that people write favorites enzymes you know two thousand just and the result is that and I'm showing specifically these two photographs the upper one is in Germany 10 000 kilometers away from here and the lower one is in South Africa about 200 kilometers away from here and in both cases we get the same end product we get iron we see here the iron in that case here as well and um in that case it's well buffered so the pH here is seven but in that case the pH is two no but the process is that lead to there on the right side are exactly the same no matter where you are on Earth well that's that's a key thing so sometimes when I came 10 years ago I read that the situation in South Africa is special specific different no it's not different the chemical processes are the same everywhere in the world you know therefore it's it's not different from a chemical point of view the knowledge is there the knowledge is there how to treat my Buddha and South Africa had the very first zero discharge mind water treatment plant in Imam before others did it so the knowledge is in the country you know but you know the louder you cry the more money you get know that all of us hey chemical reaction you know every equal sign that you show allows one third of the group to fall asleep I will show you five equal signs so at the end you and me we will be there the rest will fall asleep but that's okay you read the wrongful anyway already okay so oh they're more than four you know I might fall asleep let's start here that is our pyrite the pyrite reacts with the water now we have two different reaction Pathways and that's uh that's important for for the understanding of the processes one is uh the normal oxidation process with water you always have to add the water of course and what we get is the sulfate that is here and please ladies and gentlemen wherever you are it's sulfate it's not sulfates there are no sulfates in the water it's one sulfate it's one nitrate it's one phosphate forget the s for the rest of your life not when you are a mineralogist huh they have sulfates because they are different minerals that can be sulfates yeah and we get iron too Iron II is the ferrous iron the third sign and protons and protons is acid so you can clearly see that reaction here it causes um acid and the sulfate plus that iron that we have so this is the end uh that's uh the non-biter biologically activated reaction and the other one is microorganisms here and that reacts with the Iron II and the sulfide uh plus the oxygen with the same result here so here were microorganisms in between involved in that process and they're really those microorganisms because could be that as a biologist here on on one side they're directly feeding on the crystal they're sitting on the crystal if you look to attempt photograph you can see how in others they don't like that they're a little bit further away the weight answers also already sulfate now that's easier for them to digest um so they're a little bit further way but what happens next is a slow and a fast process we are adding oxygen to that reduced form of iron here and um what happens next is that we get iron three it's a fairy diamond and we have another reaction uh with the chloride you see the pyrite was here but it's here as well and that will also read the iron too we I read that sometimes from some people here in South Africa oh we just need to go deep down in the mines there is no pyrite oxidation anymore Foundation happens in two ways the oxygen and the ferrous iron the ferrous iron also oxidizes the pyrite it's lower and the oxygen with oxygen but it's not true that there is no parietal oxidation anymore in the deeper parts of the minds it's slow yeah that's that's true and what we get at the end is what we call for example yellow boy and in two slides I will show you how it looks like the iron oxide you know that's the red color that we see here and here you can see I'll let it go you see here the sediment at the bottom so now what happens I told you that that water that is just going around there when we took the sample it had a pH of roughly 6.5 so it was circum neutral if you measure the pH of that one very likely it will be about five or six so what happens is exactly what you can see here once the iron oxidizes you're producing Pro this is the metal acidity now that that contributes to the acidity of the water but not to the acid of the water yeah the acid only is the protons here that's what happens okay two more for me and then Elka will type over um good and bad that are relative terms now we read that we have good wine water Bad Mind water it really depends on what you want to do with the water it really depends on where you are with your water so what we read quite often mine water is bad it causes pollution with heavy metals when I read that sentence my students have to leave the room immediately because who of you can Define what is a heavy metal no one that's what I was hoping for uh there are four zero forty different definitions for the term heavy metal and because we don't know what you mean we don't use it and the U part U part is the international Union of pure and applied chemistry this is the Bible sorry when I use that word the Bible for geochemistry for for chemistry they clearly say we must not use the word heavy metals so please don't use this I don't know what you mean with heavy metals do you know what a heavy metal star is I like you because you're sitting in the first part it's a musician of course but what is it up there a heavy metal star is a star that has more helium than hydrogen because for the astrophysicists helium is a heavy metal so if you're writing about the heavy metals in your water do you mean that you had a lot of helium it does not I know that I'm aware of that but please let's use correct terminology and let's avoid the word heavy metals in the future because there are simply no heavy metals if you know what you have if you have cadmium if you have lead if you have mercury or zinc write it down yeah do you know how many Publications we have in our journals and books that start with heavy metal analysis the first element is arsenic sorry arsenic is not a metal at all so how can it be a heavy Network the next one is aluminum are we flying in planes with aluminum yes we are because it's not heavy so um it's really a confusing word the key problem is and that's what we are using it's the semi metal semi-metal and metal contamination of the water and that causes that our streams Lakes are contaminated with the okra that you see here you know and because the OK is sitting on the stream bed the microorganisms cannot feed in the Stream bed anymore and when there are no mitral organisms you don't get other uh organisms in the water and then you don't have fish so it's not the water that is negatively affecting the fish in most cases it's they don't have anything to feed because the okra is there and the microorganisms and soul Plankton that cannot start to grow um that's what I just said um so we have a lot of negative effects on all aquatic ecosystems you know that means oceans that means lakes or that means streams we see the change in the visual ellipse appearance which you will see in the next slide and uh we cannot use it anymore for drinking or irrigation water but not all mine water is problematic and with that slide I hand over to alter that is in Wales we took it last month you see here a nice stream and here you see it's a contaminated water and elky wrote it down somewhere a couple of hundred tons per year of cadmium and Lead and that's a problem for the people there okay and now I hand over to Elke I don't know how you can do that but I'm glad he's done with the chemistry inside it's just quickly check the chat okay we can check this later because we talk now about what can be done because we're here to find Solutions so let's see what can be done with the mine water best of all we need to understand the situation and the problems so we need to investigate the main water situation we have how can this be done first of all and most commonly with geochemical to investigate the geochemical composition so we take water samples and we analyze them usually your on-site parameters so we go out there to the mining side and we measure temperature Electro conductivity redox potential oxygen concentration handful of parameters and you measure them in the field because we want to have the the direct data from the field and not what the lab analyzes because then obviously for example the temperature is not correct anymore then main ions and Trace elements sometimes isotopes and Organics also sometimes for example in Germany we had a project where we analyzed the mine water for pcbs so this is one column for the investigation the second one is to understand the hydrodynamic situation in the mind and I will talk about all these points in the next slides a bit more in detail just for you now even overview so first of all we can conduct Tracer tests then we can do a depth profile measurements in the flooded mine even inside a mining Lake but usually inside the flooded shaft flow measurement with surface water but also inside the mine and analog and numerical modeling okay just an overview I will come to all of these in the next slides but there is a third column that we need to look at if we want to understand the Mind water situation and the problems that come with it and this is the longevity longevity of the Mind water quality he called his first flush have a look at this curve you can see here's the mouse on the y-axis is the total acidity but this could also be concentration iron concentration sulphate concentration and then the x-axis is the time and you can see that this point is times zero and this is when the mine water is first discharging out of the mind and then usually the concentration or the acidity the mind or the quality gets a bit worse and then the quality improves over time in a more or less exponential curve in this process the change of the Mind water quality over time is called first Flash and it's very important to consider the first Flash and yeah the change of the mind with the quality because it really depends how you manage the mine water because you handle this quality different to this quality so just keep this in mind but now let's come to the hypergeological investigation methods Tracer tests treasure tests SSH can be done with surface mining influence water also inside underground mines and we use the Tracer tests to determine the Flawless velocity but also flow paths so where the water is Flowing inside the mine or for example also if dams are properly sealed or if mine water is seeping through the den possible traces of fluorescent Dice and I brought a few for you here just for the online people beautiful colors will be yes in one and sodium then another possible Tracer are sports but they are not really used anymore and then microspheres and you can see in this picture here on the top this is under the UV light so the microspheres are injected at one side of the mine and then you measure the concentration at different points in time on another location and you can count out how many of these microspheres are inside the water a few pictures for you this is profit injecting um fluorescent dye I think the green one the uranine and inside the mine in Germany directly into the shaft via a pipe so it's possible to inject the Tracer on the water surface but we also have a device that we can lower down inside the mine and then check the Tracer at a certain depth so for example we have an on setting station in 200 meter step and you want to check the Tracer there we can open this device in the trace is inject it exactly where we want to have it then another application here is an increase investigation this is the place box part and yeah we injected also uranium sodium fluorescene to see how the water increases into the mine and another example question showed it before this is a settlement point from a coal mine and they want the iron to participate and for this the water needs to flow as long as possible through through the settlement Pond but what happens the water is taking a shortcut and you can nicely see this with the green color that it's not evenly distributed and that it's just flowing there on the side so we could give the mining company advice to um yeah in barriers to have a more even distribution of the water in the settlement pond just a few applications there are many more for Tracer tests but this is what we mainly use traces for in mind water research and if you want to know more about traces you can participate on the 12th of September in the webinar diet tracing in practice and one of the topics in this webinar with different speakers will be about floors and Tracer dies and Mining influence water just send us an email and then I think it's a two hours webinar next week okay the next investigation method it's depth profile measurement you see one of our colleagues here he is holding the device and be a bit more in detail this is a probe from the company C and sun and this is the one we have at our lab and um so of course this is the the metal device and the actual probes are on the bottom and we can measure temperature electrical conductivity in the pH value and just for reference to see how big this device is so the probe is lower down into the flooded shaft and then over the depth we can measure different parameters and yeah I have an example for you from mine in Portugal which a retirement the former uranium mine and we measured temperature and electrical conductivity you can see this on the x-axis and the density is calculated from temperature and electrical conductivity with the units formula and yes on the y-axis is the depth of the mind so what do you see here what catches your attention there is a big jump in the jump it's a jump between two water bodies and we call this stratification so the Mind water body is stratified into an upper water body with a lower temperature and just a kind of electrical conductivity of 800 micro Siemens per centimeter and then we have a lower water body with a higher temperature I mean the difference is for Kelvin which is quite a lot in the very high electrical conductivity to explain this in create a detail you need to look at a cross section the Santa Barbara Russia is in the middle this is where we measured and remember in 200 meters depth was the jump and this shows us that there is a warm mineralized layer or water body and a cold fresh water body another interesting thing is that HR P4 you see on the side the water is discharging from the mine but the water that is discharging there is only the water from the cold fresh water body and because of this this homo uranium mind can treat the Mind water just with a relatively small passive treatment plant and they don't need a big active treatment plant and because it's just this water of relatively good quality that discharges from the mind so imagine the stratification would not be there there would be a much bigger problem okay next investigation method discharge measurement you probably all know the impeller method where you go inside the stream and you measure with an impeller but there's another method that we preferably use with mining influenced water and this is the salt dilution method also called slack injection method and I would like to explain this to you as well the S stands for Salt Lake because we just use normal um NaCl normal table salt you can see me there and the picture with a big package mixing and this salt to dilute it with the stream water so I took a packet with Sweet Water put salt inside and then mixed it and this is the salt we will inject into the stream which you can see here this is otherwise it's called slug injection because it's be quite fast and then on the other side this is here and with the other side I mean this is a certain distance that we um choose from the widths of the Stream So if the stream is two meter wide we need about 80 to 100 meters of length just to give you an idea between the injection point and the measuring point so when we measure we install usually two probes inside the water and the probes measure the electrical conductivity but because the electrical conductivity is proportional to the concentration of the salt they get a nice curve of the concentration and so there was no choice injected and then this tray is a cloud that is flowing through the stream is arriving and we see this nice Peak and then obviously the stream is flashing the Tracer out and the curve goes back down here and with the area under the Curve we can calculate the discharge of the Stream and this can be done with an extra spreadsheet and a normal electrical conductivity probe but our team has a set it's called TQ Tracer from the company summer and with the software it shows us directly why we are still in the field very accurate data of the discharge of the Stream last one about hydrogeological investigation methods is modeling character modeling you get nice colorful pictures for example with feed flow or spring or we also use chromosome motor physics but there's also analog modeling for example with the Agricola model mine this is an analog model that we have at our research chair and here you can see a picture of the model so it's the mine the four shafts and four horizontal levels and we can conduct very different kind of experiments in this analog mind so at the moment we are running a tracer test you can see here Tracer and the syringes and their sampling ports everywhere in the model and I take samples after we injected the trailer to see where is the Tracer flowing which flow patterns do we have how long does it take to flush the Tracer out why do we do this because we prepare a tracer test for a coal mine and we want to see what is the best setup for such a tracer test because in the field you have one chance and it's very expensive but here we can repeat and experiment every few weeks with different setups with different Tracer concentrations with different injection points so it's very nice and it's quite unique it's the only one in the world and if you want to come and see it you can come and visit us at our mind water lab and we can give you a tour okay back to the um actual presentation what can be done because investigation doesn't stop there because we need to have intervention in different phases of the Mind life cycle this can be for example in situ remediation so we can use the stratification and take care if the stratification exists not to destroy the stratification for example by pumping or we don't pump it all so that the stratification can develop because we figured out that in almost every mind worldwide where there is no pumping stratification develops so mind water and mine water hydrodynamics need to be understood by the responsible people to make clever decisions to see when can we pump when can we not pump should we let stratification develop because then we have this nice cool or more water bodies it's an option but then what is usually done with mine water just remove this jet here yeah but it's usually done is treatment and there are two main ways for treatment the first one is active mind water treatment and this is just now very short explanation if you want to read more I can recommend this book um active mind water treatment is a physical or chemical process in Human Action is required and usually the pH value is adjusted to reduce the metal solubility or for acid water there's neutralization and then in PH increase for the metal precipitation the other option to treat mind water usually mine was a that is not so strongly contaminated or polluted um is passive mind water treatment and this one relies on natural chemical or biological reactions and there is no addition of chemicals energy or both okay just to give your a few examples because it's always nice to see pictures this is and this is the HDs searching Point HTS stands for high density sludge and what you can see here is the process that comes after the neutralization with lime and after the pH increase to participate in the metals so the sludge is pumped inside here and then the sludge settles and then the more or less clearer cleaner water is decenting and in this case you can say a decant it's decanting outside for further treatment okay so this is HTS and this is one of the most common ones the next one is resverse osmosis and this is a type of filtration with extremely small pore sizes and then freeze crystallization freeze crystallization for mind water treatment is very unique for South Africa it was invented here and I think this is something South Africans can be proud of and that we have this very unique treatment method here for mine water and it uses one third less energy than distillation for example and the method is that the pollutants do not incorporate into the ice crystals so you have the pollutants on the one side and then the ice crystals on the other side this was active now we talk about pace of Mind water treatment and I showed you the profiles and the cross section of the smile in Portugal and I said a shaft P4 there's a passive mind water treatment plant and this is this relatively small passive mine Water Treatment Plant so there are settling points here where the water is Flowing out then there is a reed bed here this is um also for precipitation and then there are floating mats here and this is that the iron reduce anticipate further and then the water is the water quality is good and it can just be discharged in the next stream so passive mind water treatment is very interesting it's not so common in South Africa but for example in the UK it's widely used okay back to what can be done because there's a last point that you have to talk about what can be done and this is monitoring and Aftercare and monitoring Aftercare we should not forget about this because as I said the Mind water changes over time it's not the same water the year the Mind water discharges first from the mind and 10 years later so water samples need to be taken regularly to check to monitor how is the quality of the water changing and what needs to be done to improve the situation or can is it fine now or does it get worse due to any events and peace of mind water treatment is quite nice because you don't need to put in extra energy but obviously after a while the settlement point is full and then somebody needs to come and excavate the sludge and dispose it and then also something people not really think about you put pipes there but there's incarceration so after a while also pipes need to be exchanged just to give you a few ideas about monitoring and aftercare to show it the slide of what people think about mine water at the beginning and almost everybody said nah it's bad and it's it's not good for the environment it's polluted water but we should also consider what can be done with my water because mind water also has potential and I would like to show you a few ideas where mine water is used for example for drinking in irrigation water after after treatment here in South Africa for drinking water geothermal use of mine water usually the water is small that comes out of the mind and it can be used for heating of buildings an example Springfield in Canada and the the length of the arrows should show you how much is it used to our knowledge worldwide so does you just get an idea where or how my note is used in in which extent sorry hydropower there are past examples for example from the hearts or all mountains in Germany but they are also um disability studies for example in Spain then pump hydropower and also visibility studies but with pump table power there's always a big risk of earthquakes just to keep this in mind then green energy micro or mini turbines this is a picture of a micro of more like a mini turbine [Music] and to our knowledge and you also talk to other colleagues just when we met them now at the conference in the UK currently we have no example where micro mini turbines for green energy Productions are used worldwide a good thing mind water as a resource everybody is talking about that we should use mine water for raw Earth elements for lithium but to our knowledge this is just a lab stage nobody really built a plant until now to really get the resource out of the mine water then post-minding use of landscape um for open pit mines but also for underground mines one of my favorite examples because a few weeks ago I was with my kids at Gold Reef City and these guys told me they use the water they pump out of the mine for the water attraction that is there so next time when you float around on this ring to think about it you float on mine water and health and Spa so the radon enriched water just an example in Pakistan in Austria by the end of every Castle we should think what can be done in South Africa because minewood has potential and we can see the potential we can also see the potential in South Africa and just to give you an idea with the yellow goldish um color this is where we are in South Africa so geothermal use is not really used hyperpowers not used green energy not really used so I want to show you that there's a lot of potential and a lot can be done with mine water and Yes mine water is not good for the environment but we need to have new ideas what can be done because it's there the water so yeah just to show you second last slide helpful resources because I know you're all super interested now mind water and you're you want to give up with the normal geology and want to become a mind water expert so let me show you a few helpful resources and we need to make a bit of advertisement for the international mind Water Association because there's the president and I'm the treasurer so if you use the chancellors for the online people there so at the international mind Water Association is an NGO at the moment we have 500 members worldwide from almost every country you can think of and there are the main water experts and they're connected with each other and we have an annual conference this year we were in UK and Wales next year we will go to Morgantown in the US in the year after Portugal Spain so it's always everywhere in the world it was a nice thing to travel and um for you as students we have a which is quite and then you add our own journal mine was in the environment for Tennessee we have a newsletter we will Implement an expert portal now so let's say I have a question about geothermal application for mine water I can check in our expert database and I know I need to call Dave in the UK because he is listed as the expert for this and we will also Implement a young professionals Network then here is Visa mind Water Division then Africa is the Mind water Atlas worldwide especially for asset mind range and as a drug trainer desktop you can take the webpage we just can send a Prof an email because he is 32 33 years now experience and knowledge so please check page a lot of questions are listed that you can doubt and as I said you're all interested now in mind water research and you will run away from here and come to us we're joking and we like to go in the feet to the field but um to have the mountain lab and really if you want to come and visit our mind we'll let you you can come instead we have different rooms and also with the analog models and check it out and we also have possible topics for master of PhD thesis you can see a few here just ideas but you can also come with your own idea and any of you can't talk about now or if you want to participate in the webinar about traces please send us an email all right fantastic thanks to both of you that was nearing something very different and I think everyone's really enjoyed it um right so time for some questions the first audience here if there are any questions uh for our two speaker and if you could come to the front that would be very useful are there any uh questions in the live audience uh for those of you that are online if you do have a question all you have to do is raise your hand and then we'll ask you to unmute and while we are waiting there are some questions um in the chat right so those are just more comments from tamiru do we have any questions from the audience yet yes would you mind if it's different thank you very much for a really great presentation my query is if if we have the strategication of mine water and we you mentioned in one of your slides that that you could point that for hypothermal energy truly then you're going to be playing around with the with the transition zone or the the yeah the change from or the switch from the warm water to the the colder water which is healthier and then your healthier Waters gets dropped up and then it's getting good into the Zone where it's going to become warmer and a bit more reactive and So eventually that's not a long-term solution is it yeah so the the people that work with um geothermal applications for mining water we connected with them and um they said to us oh yes stratification this is orthoped new for us and this is a general thing in the mind of the community people don't know about certification they just think it's one big mind with the body which isn't so first of all we need to bring the message out the stratification and we are discussing with them that it might be an option to have a physical system so that you don't actually pump the mine water it's just you send a liquid in a closed pipe through the warm mine water so that you have less mixing or the other idea is that you um that extraction and infiltration well needs to be very far away from each other um but we personally have no experience yet with it just ideas that are floating around and yes it's important to consider the stratification thank you yes yeah so what Erica said about the closed system that um that's uh like a free these are but you put it on it but it's the way around of course you know so the liquid the organic liquid gets heated in the deeper parts of mind it's coming up again and then you can use it for heating it's cooled down and then it goes back there's only one application so far in the world in Germany where they are using that application all the other alternative would be uh use the water that is Flowing out of them because then you don't have to that's also done that's also uh done there worldwide uh roughly 100 applications at them yeah and of course if you use the water that's flowing out then you're not distracting the system but even if you use a water filling do you indeed they know the certifications you know it doesn't the stratification stays stable I mean the longest record we have 35 years okay so it doesn't right do we have any other questions from the audience yes I apprecially a certain idea really how to be fair there are people mining the three bits that you almost understands it's accumulating that it's really accumulated over many years and they reminded of this sick black slowly Roots season to Burger we've got a very good very purpose so as as a nice budget for one of your students find a good read that blacks always maybe you've got a business it's a very good idea a friend of mine she just bought a small gold mine in Finland I will plant uh read that there well I have one question from online it says how do you dispose of the Sledge yeah most of the people are disposing them off at uh waste disposal sites that is the normal way of doing it but the preferred way is how it was done when the first high density sludge my own would the treatment plant was constructed in the world in 1973 in the US they discharged the sludge back into the mine workings and that's what we are doing in the East Rand here so the Eastern wind water treatment plant is distorted the slot back into the line workings and when it's uh far away from the main shark when you don't get the sludge back into the water stream the advantages also that the sludge still contains a little bit of alkalinity which also means that you are increasing the pH uh that's also an advantage sometimes I hear people saying ah yeah but what happens when the metals dissolve again that these people should read a little bit more about chemistry when you have the metal there and around the metal you have the sludge with a high pH value it's like isolating that metal so it does not be solved I did experiments there for a German line many years ago a Canadian colleague did do a lot of experiments at a Canadian mine where they are also discharging the effect underground we don't have a single case where we saw that the sludge negatively affected the water when it was pumped back into the underground when it's far away from the central shark where you're pumping far away means minimum we notice this 500 to 600 meters that's far far away okay Suman would you mind coming to the microphone because otherwise yeah online won't see much oh is it possible to recreationalize the Mind order by decreasing the phase and also what is the effect of pressure and temperature on the Main Motors so what was your favorite part of the question if we increase the uh decrease the pH can you decrease slice them in order okay crystallize can you precipitate Metals in the mind and the the iron will precipitate yeah I can remain can remain that like we can after uh decrease in the periodic agreement that is it is a decrease going down yeah I know when the pH goes down you're dissolving everything again and presumably that's where you could Harvest things like critical metals from them right yeah we have about 20 years research no one did it so far it's only at the lab stage okay and a colleague of mine he nicely says you're spending a lot of money in getting out a little bit of iron um or a little bit of the rare elements if I look into my mind I have a caterpillar like that that gives me two tons an hour and it cost me more or less nothing and you want to spend that much money in getting out that time a little bit from the Mind water so uh we are not there yet it's uh like in the haystack also the uh what is the effect of crystalline temperature in mind not perfect is there any research on whatsoil restaurant in pressure say what please pressure pressure and temperature oh yeah that's what we are doing in our research team okay yeah that's uh what is that yeah thank you okay do we have any more questions from the room nothing online so just once again thank you both very much for coming it's been a great pleasure to have you here and hopefully we can we can visit your institutions all right thanks everyone we'll see you next week yeah thank you as well okay yeah thanks everyone for listening to us next week right