JoeyJoystick
Well-known member
Hi All,
So I spend a year reading Hoke's, GRF and a whole bunch of documents I found on-line. But similar to getting your drivers licence, you only learn until you practice and practice and practice. Or so I figured. I felt confident I could do it. But I was equally confident that Murphy was just around the corner and waiting for a chance to screw things up for me. lol.
I had ordered some kit. Some glassware, chemicals, hotplate, filter set-up and a whole bunch of other things. Not quite everything yet, but enough to get me started I figured.
I had some old (late 1800s) jewellery made from Indonesian gold. I knew from a jeweller, who told me that it was beyond repair, that this gold contained a lot of copper.
Anyways, I decided to remove the base metals with Nitric Acid 68%. I buy a liter for 2.5USD so I do not feel the need to be careful using this for monetary considerations. I added the gold into a beaker and covered it with Nitric Acid. I think this was too much acid though, but I do not think that this would cause problems down the line. No major issues anyway. I was impressed at how quickly the base metals dissolved and the colour changed from clear to a very dark greenish liquid. Kind of clear, but still dark-green. The reaction must have stopped within 30 minutes but I left it for 2 days standing. (I have plenty of time...) Surprise! The next day it was clear blue. Almost like aqua-marine-blue with very slight haze of green over it. I believe I have read about this in the past somewhere, but now that I am looking for it, I can obviously not find this. (Any Ideas?)
So now I pulled out my newly purchased vacuum pump. Set up my filter unit consisting of a 1l Erlenmeyer flask and a glass Buchner funnel with a pore plate. I used the slow filters that I had. Because I have time and it is my first time; I figured I should do it properly. Ok, in hind side that may not have been the best idea though. The filter got clogged relatively quickly and it took 1.5 hour to drain it through the filter. Carefully removed the filter with a small bunch of gold in it (admittedly, a very small bunch...) Rinsed all and cleaned all after having put the filters and the gold in a separate jar. Now filtered it again and again with a slow filter. After having used a slow filter I felt it was a really stupid idea to now use a faster filter. But, this time the filtering went very quickly, as in less then 5 minutes. Done this 3 times over. And the blue liquid left over was very clear by now.
Due to the washing and rinsing the 150ml Nitric Acid had now increased in volume to about 500ml. I guess I need to be more cautious next time I rinse with water. Anyways, I figured I should boil off some of the water. And now I noticed somethings strange. Just before it started boiling, I noticed a white powder precipitating to the bottom of the beaker. I am specifically saying 'just before it started boiling' because I can not see inside once it actually starts boiling. This does not mean that it is not there anymore though. Does any of you have a clue what this may be? Could there be silver in it as well? By the looks of it this should be a very small amount though. In comparison, I guestimate this to be about 10% of the total gold I got in the filter. But me guesstimating on my first run is not a very scientific approach of course. I will keep all the liquids for later and treat further.
Now some reporting on the kit. I know I can be a bit of a snob when it comes to buying tools. However, I had already decided that this was going to be a hobby thing and not (not for now anyways) a money making thing. And when I saw the price difference between proper German kit and some cheap stuff from China I decided to go for the latter anyway. I bought everything online from platforms such as AliExpress. Interesting experience... Got things which arrived broken and encountered some obvious quality issues. I am gonna summarize this in a bulleted list with some questions here and there.
- Since the amount of glassware I am dealing with at this stage a small I figured I should make sure that all joints are the same and I have chosen for 24/29 joints. I noticed that glassware from different manufacturers have a slightly different fit. Not to the point where the joint is compromised, but I can feel it is not a perfect fit. Is this normal? Is this reason for concern?
- On most glassware I can see that it Is a relatively cheap kind of glass. Not like my crystal glasses in the kitchen if you know what I mean. I am a little worried about the glas breaking when heated. Is this concern justified? Are there other concerns I should consider? Safety Concerns I am most worried about, but there may well be other practical issues I have not considered .
- The glass Buchner funnel with pore plate and 1 set of filter paper came together in the kit. I bought some additional filter papers of different grades. Surprise; all filters are slightly too big for the poor plate and consequently creep up on the side wall of the Buchner filter for 2-3mm on one side while the other side is flat down all the way to the edge. I guess this is what happens when you go the cheap way.
- p.s. Filter kit came with 1l erlenmeyer flask, 500ml Buchner funnel, filters and a vacuum hose. All for about 33USD. So that is not too bad I figured.
- Vacuum pump. I was really surprised to be able to buy a small vacuum pump for only 50USD. Obviously I wondered if, and how well, this would work. So when I started the first filtering I noticed the pump was getting seriously hot. So I turned it off and every few minutes or so I turned it back on for 10 seconds. Sure enough after a while the pump did not want to start anymore, but once I let it cool down a bit, it started to work a little better again. Again, quality comes at a price. No bad feelings. It works like that. You get what you pay for I believe. But still annoying. lol.
- During the boiling off of the water I noticed that it only started to boil at about 115-120C. Is this due to the mixture of Nitric with water and a consequently increased boiling point or may this come down to a really bad quality Chinese thermometer? I also notice that once the level was reduced to a little less that the initial amount of Nitric Acid which I had used, it kept fuming. Even when it cooled down. Any suggestions here? I want to keep this for later when I have what I need to analyse it. But it is obvious that I can not keep it in a closed storage container. This will likely blow-up in time when pressure builds up and this is not the kind of stuff I want happening on my watch.
- One more comment on the Blueish liquid. After boiling off the water, it was not the pretty clear blue I described earlier. The colour was kind of the same, but just not clear anymore. It had like a whitish haze over it. Presumably this is the white precipitate I was talking about earlier, but I am not sure. And then, of course, after letting this settle for several hours, the liquid is all clear again and the white precipitate has settled on the bottom. Filtered this 2 times and I clearly caught a lot of precipitate in the filters, but there is still a white haze over the liquid, which than slowly settles to the bottom. But only a very small amount. I don't think I can clear this with filtering, because it is quite obvious that it passes the filter fairly easily. Maybe a separating funnel? I will give that some thought.
p.s. Let me be clear about the colour. It is called aquacyan in Wikipedia. https://en.wikipedia.org/wiki/Aquamarine_(color) when you go to the bottom and on the right of 'Shade of Cyan' click on 'Show' and you will see a colour called 'Aqua/Cyan'. This is the colour of the blueish liquid I was talking about. Describing a colour is difficult, but remembering all these colour names is equally difficult... Who oh who came up with all those names and colours? lmao.
Anyway, this was a lot of fun. I will update next time when I continue, but this will take a little while.
Joey
So I spend a year reading Hoke's, GRF and a whole bunch of documents I found on-line. But similar to getting your drivers licence, you only learn until you practice and practice and practice. Or so I figured. I felt confident I could do it. But I was equally confident that Murphy was just around the corner and waiting for a chance to screw things up for me. lol.
I had ordered some kit. Some glassware, chemicals, hotplate, filter set-up and a whole bunch of other things. Not quite everything yet, but enough to get me started I figured.
I had some old (late 1800s) jewellery made from Indonesian gold. I knew from a jeweller, who told me that it was beyond repair, that this gold contained a lot of copper.
Anyways, I decided to remove the base metals with Nitric Acid 68%. I buy a liter for 2.5USD so I do not feel the need to be careful using this for monetary considerations. I added the gold into a beaker and covered it with Nitric Acid. I think this was too much acid though, but I do not think that this would cause problems down the line. No major issues anyway. I was impressed at how quickly the base metals dissolved and the colour changed from clear to a very dark greenish liquid. Kind of clear, but still dark-green. The reaction must have stopped within 30 minutes but I left it for 2 days standing. (I have plenty of time...) Surprise! The next day it was clear blue. Almost like aqua-marine-blue with very slight haze of green over it. I believe I have read about this in the past somewhere, but now that I am looking for it, I can obviously not find this. (Any Ideas?)
So now I pulled out my newly purchased vacuum pump. Set up my filter unit consisting of a 1l Erlenmeyer flask and a glass Buchner funnel with a pore plate. I used the slow filters that I had. Because I have time and it is my first time; I figured I should do it properly. Ok, in hind side that may not have been the best idea though. The filter got clogged relatively quickly and it took 1.5 hour to drain it through the filter. Carefully removed the filter with a small bunch of gold in it (admittedly, a very small bunch...) Rinsed all and cleaned all after having put the filters and the gold in a separate jar. Now filtered it again and again with a slow filter. After having used a slow filter I felt it was a really stupid idea to now use a faster filter. But, this time the filtering went very quickly, as in less then 5 minutes. Done this 3 times over. And the blue liquid left over was very clear by now.
Due to the washing and rinsing the 150ml Nitric Acid had now increased in volume to about 500ml. I guess I need to be more cautious next time I rinse with water. Anyways, I figured I should boil off some of the water. And now I noticed somethings strange. Just before it started boiling, I noticed a white powder precipitating to the bottom of the beaker. I am specifically saying 'just before it started boiling' because I can not see inside once it actually starts boiling. This does not mean that it is not there anymore though. Does any of you have a clue what this may be? Could there be silver in it as well? By the looks of it this should be a very small amount though. In comparison, I guestimate this to be about 10% of the total gold I got in the filter. But me guesstimating on my first run is not a very scientific approach of course. I will keep all the liquids for later and treat further.
Now some reporting on the kit. I know I can be a bit of a snob when it comes to buying tools. However, I had already decided that this was going to be a hobby thing and not (not for now anyways) a money making thing. And when I saw the price difference between proper German kit and some cheap stuff from China I decided to go for the latter anyway. I bought everything online from platforms such as AliExpress. Interesting experience... Got things which arrived broken and encountered some obvious quality issues. I am gonna summarize this in a bulleted list with some questions here and there.
- Since the amount of glassware I am dealing with at this stage a small I figured I should make sure that all joints are the same and I have chosen for 24/29 joints. I noticed that glassware from different manufacturers have a slightly different fit. Not to the point where the joint is compromised, but I can feel it is not a perfect fit. Is this normal? Is this reason for concern?
- On most glassware I can see that it Is a relatively cheap kind of glass. Not like my crystal glasses in the kitchen if you know what I mean. I am a little worried about the glas breaking when heated. Is this concern justified? Are there other concerns I should consider? Safety Concerns I am most worried about, but there may well be other practical issues I have not considered .
- The glass Buchner funnel with pore plate and 1 set of filter paper came together in the kit. I bought some additional filter papers of different grades. Surprise; all filters are slightly too big for the poor plate and consequently creep up on the side wall of the Buchner filter for 2-3mm on one side while the other side is flat down all the way to the edge. I guess this is what happens when you go the cheap way.
- p.s. Filter kit came with 1l erlenmeyer flask, 500ml Buchner funnel, filters and a vacuum hose. All for about 33USD. So that is not too bad I figured.
- Vacuum pump. I was really surprised to be able to buy a small vacuum pump for only 50USD. Obviously I wondered if, and how well, this would work. So when I started the first filtering I noticed the pump was getting seriously hot. So I turned it off and every few minutes or so I turned it back on for 10 seconds. Sure enough after a while the pump did not want to start anymore, but once I let it cool down a bit, it started to work a little better again. Again, quality comes at a price. No bad feelings. It works like that. You get what you pay for I believe. But still annoying. lol.
- During the boiling off of the water I noticed that it only started to boil at about 115-120C. Is this due to the mixture of Nitric with water and a consequently increased boiling point or may this come down to a really bad quality Chinese thermometer? I also notice that once the level was reduced to a little less that the initial amount of Nitric Acid which I had used, it kept fuming. Even when it cooled down. Any suggestions here? I want to keep this for later when I have what I need to analyse it. But it is obvious that I can not keep it in a closed storage container. This will likely blow-up in time when pressure builds up and this is not the kind of stuff I want happening on my watch.
- One more comment on the Blueish liquid. After boiling off the water, it was not the pretty clear blue I described earlier. The colour was kind of the same, but just not clear anymore. It had like a whitish haze over it. Presumably this is the white precipitate I was talking about earlier, but I am not sure. And then, of course, after letting this settle for several hours, the liquid is all clear again and the white precipitate has settled on the bottom. Filtered this 2 times and I clearly caught a lot of precipitate in the filters, but there is still a white haze over the liquid, which than slowly settles to the bottom. But only a very small amount. I don't think I can clear this with filtering, because it is quite obvious that it passes the filter fairly easily. Maybe a separating funnel? I will give that some thought.
p.s. Let me be clear about the colour. It is called aquacyan in Wikipedia. https://en.wikipedia.org/wiki/Aquamarine_(color) when you go to the bottom and on the right of 'Shade of Cyan' click on 'Show' and you will see a colour called 'Aqua/Cyan'. This is the colour of the blueish liquid I was talking about. Describing a colour is difficult, but remembering all these colour names is equally difficult... Who oh who came up with all those names and colours? lmao.
Anyway, this was a lot of fun. I will update next time when I continue, but this will take a little while.
Joey