The M44 Test Run & Process Details

[kurtak]

Ok I have done my test run on Jerrys process (from here on referred to as the M44 process or just M44) along with comparative testing of 3 other process (all run at the same time)

I was actually done on Wednesday but needed time to compile it into a format to present to the forum (as suggested by Lou) & as well wanted Jerry to run the process for the purpose of doing a full discloser video --- he needed to get some material together & then had some weather delays --- also I wanted run the process one more time in & of its self & I also encountered some weather delay

I was not really able to take notes because of having 4 processes going at once & as well I had Jerry on the phone for the full run so he could walk me though it - with Jerry on the phone I also could not take pictures while running the processes - however I got a pic of the starting set up as well as pics after

Before Jerry decided on the name M44 he had referred to it as "his version of reverse AR" --- though it is not really a version of reverse AR - it does have somethings in common with it - first & foremost of which is that it works with having both chlorides & nitrates in solution at the same time --- the difference being that instead of dissolving the gold but not the base metal - you want to dissolve the base metal but not the gold --- so - like reverse AR it is "important" that a balance be maintained between the nitrates & chlorides - if you flop (up set) the balance you will have a mess - meaning just like reverse AR if the balance is up set you will dissolve both gold & base metal

The Claim

The claim is that the M44 process is near to as fast (meaning with a narrow plus/minus factor) as nitric for dissolving base metals in order to recover the foils from gold plated material for refining - with copper/brass pins being the most discussed - So I was originally going to run the test with just the M44 process & nitric --- however then it was brought up that "hot" ferric Chloride (alone) could be used &/or ferric chloride with an oxidizer to do the job near as fast as nitric --- so I decided to include each of those in my testing

Note; - I have never used anything other then nitric for my foil recovery of copper/brass pins simply because I get my nitric cheap & in bulk - that includes that I have never run the AP/CuCl2 process

Therefore the claim is that if you want to recover your foils with the speed of nitric - but ether can't get nitric &/or have to pay a outrageous high price for nitric - then the M44 process is an alternative to nitric

Objective

So my objective in my testing was to run each (all 4) of these methods "at the same time" as a comparative test of each process to the speed of nitric to see if it (they) actually meet/met the above claim(s)

Setting Up & Equipment

I set up outside as the project was larger then I could run in my lab/fume hood (see pic)

Nitric process; - I used a stainless steel 2 gallon pot (left side of work table in the pic) & single burner hot pate - this got moved over to its own table (before actually starting) so I didn't have Nox fumes at the table I was working the M44 process on

Hot ferric chloride & ferric chloride with oxidizer; - two 4 liter beakers (1 for each process) & a griddle type hot pate (to hold both beakers)

M44 process; - 1 gallon Vision glassware pot & single burner hot plate, 4 liter beaker (used to prep ferric chloride)

Other equipment; - scale, smaller beakers for measuring chem, 3ml pipets, large plastic spoons (like used for cooking) 1/2 teaspoon measuring spoon, 2 liter vacuum flask & filter funnel, 3 plastic colanders & 3 plastic buckets (for filtering)

Chemicals

68% nitric, D-water, ferric chloride, sodium nitrate (this is 16% [or 16-0-0] Hi Yield brand nitrate fertilizer) HCl, 3% H2O2

Material

The only material I had on hand was 4 lbs of a mix of low grade & very low grade pins that had been incinerated (to relieve them from there plastic housing) & leftover from being used as my collector metal for smelting - so weighed out four 1 lb batches

Note; - its to bad the discussion of the M44 process didn't come up a couple weeks earlier because I had just processed about 10 lbs of high grade pins from which I got a nice 31.4 gram bar --- it would have been nice to have had those pins for this project

Running The Test

The first thing Jerry wanted me to do was concentrate/saturate/load the ferric with more iron for the M44 process - so the night before I put 1 liter of ferric in a 4 liter beaker tossed in some iron laminates from a transformer casing turned the heat on & actually boiled it - this took about 1&1/2 hour - turned the heat off & let set over night (this was done in my fume hood)

Next morning the ferric (brown) had turned to ferrous (green) with green ferrous crystals in the bottom & about an inch of heavy kind of gooey foam on top - so I called to tell him what I had - he said not to worry - just turn the heat on to about medium heat & when the crystals start to get soft & mushy turn the heat up on high & let it boil for a while & the crystals & foam will dissolve back into solution & it will go back to brown (this was done in my fume hood)

So while I was waiting on that I went around & double checked that I had everything in place for the rest of the testing - when the crystals in the ferrous chloride got to a point of being mushy I went out & put 1&1/2 liter (1500 ml) of ferric chloride in each of the 4 liter beakers on the griddle hot plate for the hot ferric test & the ferric w/oxidizer test & turned the heat on medium/high to pre heat this ferric (the SS nitric pot had its 1 lb metal & 2 liters D-water waiting to add the nitric)

When the ferric/ferrous (for the M44 process) had re-dissolved the crystals & foam & gone back to brown (remember - this was boiling) I turned it off - called Jerry - went out & turned the ferric testing griddle up on high - went back in to the lab & brought the ferric/ferrous (1 liter) out - poured it in the Vision glassware pot & turned on its hot plate

Note; - my phone is now turned on to speaker phone mode & setting on the table so Jerry can walk me through the M44 process

I then went over to the nitric pot & poured in 1 liter 68% nitric - went to the ferric griddle & put 1 lb metal in each beaker & then went to the M44 pot & added its 1 lb metal - then added six 1/2 tea spoons of the 16% sodium nitrate - I then added about 10 ml 3% H2O2 to the ferric w/oxidizer beaker

When the sodium nitrate started to react in the M44 process - about a minute or 2 (the reaction is like the fizzing you get when you "slowly" pour a coke into a glass - so "small" fizzing bubbles) I added 15 ml HCL - this changed the reaction a bit - the bubbles got a bit larger & it started to roll a bit - I added another 15 ml HCl & the reaction started to roll a bit more (Jerry is on the phone asking me what I see & telling me what to do)

Note; - I should add that I have all my metal pulled to one side of the pot & I am making my chem additions to the other side of the pot & the above reactions are taking place on the side of the chem additions

So I added another 15 ml HCl - this started the reaction to start to work more on the edge of the metal near the center of the pot - I added another 15 ml HCl - this started the reaction working even more on the metal side which also started a flow back across the top to the nonmetal side

When this reaction started to die down I added another 30 ml HCl - this really kicked off the reaction working on the metal side with the flow to the nonmetal side

So I went over to the nitric pot & added another 500 ml nitric

Note; - not much going on in the ferric beakers so I add another 15 ml H2O2 to that beaker

The M44 reaction was slowing down so I added another 30 ml HCl - this time the HCl addition did not kick start the reaction again (it did a bit - but not like it should) this is the indicator that you are about to flop (up set) the chem balance (which you don't want to do or it will start to dissolve gold) so "right away" I added another 6 spoons (1/2 tea spoons) of sodium nitrate which got the reaction going again - when that started to die I added another 40 ml HCl - then went & put the last 500 ml nitric in the nitric test (now 2 liters total & this is not on the hot plate yet as its not needed at this point)

The ferric griddle beakers are still not doing much (remember I did start these with the ferric preheated & hot) so I added another 30 ml H2O2 to that beaker

The M44 reaction was slowing again so I added another 40 ml HCl & each time the reaction would start to slow I would add another 40 ml HCl - so like another 2 or 3 HCl addition --- like before when the HCl addition didn't kick the reaction off I "right away" added more sodium nitrate

Checking on the nitric test regularly between chem addition at the M44 pot at about 1 hour into the test the nitric reaction still had a vigorous reaction going but was no longer foaming heavy so I put the pot on the hot plate & turned it on high

Still not much happening at the ferric griddle (some reaction but not much) so I added more H2O2 to that beaker - this time just poured from the bottle - I would say another 50 - 60 ml

About 15 - 20 minutes after turning on nitric test hot plate on - I was working the M44 process (following chem additions as described above) when a HCl addition didn't kick off a dying reaction so added more sodium nitrate thinking I had reached that point of flopping the chem balance again - still no kick start of the reaction - hmmm - what the heck - ohhh dam the hot plate is not working - did it come unplugged - no - hmmm - well dam the griddle & nitric hot plate are not working ether - did I kick & unplug main extension cord - no - did I trip circuit breaker - no none tripped - ahhh that outlet must go to fuss box in lower part of barn not to breaker box in upper barn - ok plug into outlet I know is wired 20 amp circuit breaker circuit --- ok - good to go - wait a bit for all to come back up to temp & reactions to start again

 

[modtheworld44]

M44 PROCESS

Objective:

The goal is to be able to strip 1 or more pounds lots of gold plated material.This will be achieved by dissolving the base metals and leaving the gold foil behind.To achieve this goal the user must keep the solution balanced and not allowed to flop(flop-allowed to convert to AR).

Other Objectives:

To give a viable alternative to other processes based on,time,chemical costs,and chemical availability.

Reagents & Equipment Used:

Reagents:

Hydrochloric acid 31.45%
Sodium Nitrate 16% (HY-YIELD 16-0-0)
Ferrous Chloride or Ferric Chloride(This is the catalyst and needs to be Highly Concentrated to the point where crystals will form on cooling.)
Spay bottle with tap or distilled water

Equipment Used:

Hotplate(must be able to boil solution)
Pipette or syringe(3ml+)
Graduated measuring vessel (for tracking HCl additions)
1/2 Tsp measuring spoon(for nitrates)
Thermal shock resistant and acid resistant glass vessel(3+liters in size and has to have straight sides and enough head space left over to allow for the HCl additions.)
Acid and heat resistant Spoon
And all normally required safety gear.

Experiment Details:

This is a small list of things that I have successfully run with my process.

Pins(all kinds,copper,brass,IC legs kovar kind,fiber cpu pins)
gold filled jewelery
T05 transistors
gold plated switch parts
gold plated boxes

Here's a video I made right before I got rained out,I had to stop the batch in the middle of the process.It's still sitting covered outside and When the weather clears out,I will take some pictures of the end results.Thanks in advance for your patience and understanding.

https://www.youtube.com/watch?v=oI8jMrMY_18



modtheworld44

 

[kurtak]

Part 2

When I blew the fuse on the first outlet plug in we were into the test about 1 hour 15 minutes & then there was about 30 minutes to figure out the problem & wait for everything to heat back up

At this point I just had to work the M44 process because the nitric was doing its own thing & didn't need any real attention & nether did the 2 ferric beakers - other then I made a few more addition of H2O2 to that beaker

I should add that it was just before the power outage problem that I first started to see any real kind of reaction going on in the hot ferric beaker - but not what I would call aggressive - what was interesting was the ferric w/oxidizer seemed to have less reaction going then the hot ferric & I had actually made a couple more additions of H2O2 (I was at about half of new 32 oz H2O2 bottle added to this beaker - so about 16 oz)

I should also add that about 45 (or a bit more) minutes in is when I started seeing foils in both the nitric & M44 process

Once it was all going back on track I proceeded with the chem additions to the M44 process as already described (nitrate followed by HCl followed by nitrate when HC doesn't kick the reaction followed by HCl

You know you are nearing the end when after a nitrate addition you still get a reaction with your HCl addition but its not as aggressive - this means you have depleted the amount of metal so there is not enough metal to keep a vigorous reaction going - start checking how much metal you have with the large plastic cooking spoon

Also - you should still have nitrate in the pot from your last addition of it - so start cutting back on your HC addition & give it a bit more time to let the chem work on the now depleting metal

I need to note that al during this process a crust builds up on the sides of the pot & as well on the surface of the solution --- this crust is caused by the nitrates - from time to time scrape the crust on the sides of the pot down into the solution - this crust also works as an indicator that you are about to up set the chem balance because as the nitrates are used up by the HCl additions the crust on top of the solution becomes less with less building up on the walls of the pot

So - unlike when you have a lot of metal in the pot & the reaction is more vigorous as part of your indicator - when you near the end with less metal for the chems to react on - you use this crust as your indicator - if it starts getting thin when adding HCl - add some nitrate to keep from flopping the balance & the just let it go --- check on the metal using your cooking spoon to feel for it &/or pull it up on the side of the pot to check it --- you can make some more small HCl additions as long as you still have metal - just keep a good crust on top of the solution

Note; - when you reach this end part of the process you want reduce the heat to medium (maybe a bit less depending on your hot plate) so that the heat is not causing a heat action of boiling & or simmering that fools you to thinking there is a chem reaction when it actually a heat action --- in other words you still want heat but not so much the action from heat fools you think you still have a reaction going

When you have no more reaction you are done & you should have a good nitrate crust on top - turn off the hot plate

Filter right away while still hot & add some water to keep the nitrates from crystalizing & setting up - if they do they will dissolve with more water during your filter/washing

I had to stop mine a bit short of have all the metals dissolved because it was approaching time for me to go in & start doing things I need to do to take care of my mom (87) & my dad (93) so I needed to get the solutions poured to there filters

Filtering

I turned the M44 hot plate off & took it in the lab to filter it with my vacuum filter - when I did that I forgot to turn off the nitric hot plate & the ferric griddle so they actually got to run about another 20 minutes & yes there was a bit of reaction still going in the nitric pot - so I turned these off & poured the solutions to there filters to let them gravity filter

I should also note that the hot ferric did not really get much of a reaction going until about 20 - 30 minutes before I shut the M44 process down & what was a real surprise was that the ferric w/oxidize seemed to have even less reaction going & they both still had quit a bit of metal in them

Because my starting material was such low grade material there was a lot of solids in the solutions so I just poured them to the filters (instead of letting them settle over night) & et them gravity filter over night - I poured just the solutions of leaving any solids that did not pour of in the vessels until the next day

This concludes the actual test run

I still have a bit more writing to do to "finish" the Results, Conclusion/Comments & & Further Work Planed part of this report (which will include more pics)

I will post that tomorrow so would like to ask that you please wait on that (the finished report) before posting any comments on this part of the report as doing so will do nothing but detract from the final (& most important part) of the complete report

Kurt

 

[Barren Realms 007]

First question I would ask is if you tested the M44 solution with stannous?

 

[Geo]

Thank you for posting. You did a good job Kurt, well done. Since I have never done a side by side, I only have my own experience to go by. I measure the difference in speed compared to AP. Anything that slashes the time needed for a process from a week to a couple of days is fast by my standards. There is also a question of safety. Any NOx is dangerous and so we figure out ways to protect ourselves. A fume hood or a stiff outside breeze. Best and next best, respectively. Ferric chloride will produce chlorine gas. Still very bad but considered slightly less harmful than NOx. Also, I watched the video. You must stay in close proximity of the reaction. A large pot of fuming NOx is hard to stand beside of without fume control. This is not something you can set and walk away to attend something else which makes it very self involved, which kind of detracts from the time saving part. You must dedicate 100% of your attention to this one process, which isn't so bad if you have nothing else to do. If it is some type of toll refine with time constraints, it may be a good alternative to nitric acid for those that nitric acid is hard to obtain or price prohibitive. Of coarse I will try and reproduce the process myself. Since there are many ways of doing the same thing, like what was said before, not better but just different.

Jerry, thank you for your time. I appreciate your willingness to share. Very smart thinking using saturated chloride and sodium nitrate to dissolve base metal.

 

[richard2013]

Question, when the M44 is on a hot plate with the presence of sodium nitrate is there possible foaming of NOx on these?

 

[solar_plasma]

Cl^- , NO3^- and acid protons in the same hot soup is nothing else [stt]then[/stt] but (a weak) AR to me. Sorry. Also only using dill. HCl and small additions of HNO3 leaves thick gold foils from TO-5 intact until the basemetals that work as sacrifical anodes are mostly dissolved. Much Ado about nothing.

Nevertheless as a good description of a well-developed variation of poor man's AR it might have its applications. Thanks for sharing.

The conclusion and moral of the story is, there is still only one sledge hammer, only one last line of defense, if nothing else works, straight AR, in all its variations. If used with wisdom also a sledge hammer can be handled with sensivity.

 

[kurtak]

Results

The total time to run the test with the clock starting at the point where the reagents were put to work on the metals & the clock stop time at the point I had to shut it down to start filtering (so filtering not included) was about 2 hours & 50 minutes --- however some time (about 30 minutes) was lost due to the blown fuse & loss of power ( that is factoring in that reactions started slowing down once the power got cut & not realizing it - the time to fix it - & the time for it all to come back up to speed)

However I also had to cut it a tad bit short of full completion as I was approaching the time of day where I have responsibilities of taking care of my mom & dad - so the 2:50 is probably a close ball park of time it would have taken for completion

Though there was still some metal in both the nitric & M44 when I shut it down they seemed to very much run nose to nose in the work they did - foils started to appear on the surface at about the same time - base metals seemed to dissolve at about the same rate - & when shut down it would be a hard call to say which still had more metal

The hot ferric & ferric w/oxidizer just can't really be compared to nitric - even though I started the ferric hot before adding the metal it took a plus/minus factor of about an hour before I saw any real reaction that indicated metal was being dissolved with any speed & it was not till near the end that it showed signs of being somewhat more aggressive - when I decanted these beakers (which was actually about 20 minutes after stopping the M44 process because I forgot to turn the griddle off when I went to filter the M44) I would say that only about half the metal had been dissolved --- I can only assume that like other reactions of dissolving metals that as the reagent loads with metal the reaction would hit a point of slowing down - so not only a slow reaction start time but a slow reaction finish time

also the ferric with oxidizer did not seem to do any better then the hot ferric - maybe a different oxidize - I did a fair amount of research but couldn't find anything other then it being said that an oxidizer could be used to further drive the ferric

As stated earlier my starting material was very low grade stuff (which is why I normally use it as my smelting collector metal) so nothing impressive to show in the way of foils - but they are there - most of them are more a ultra fine foil dust tied up in the solids (plastic ash/carbon, CB fiber glass & stannic tin) & the ferric testing also seems to have added an iron based sludge to the mix of solids - meaning the nitric & M44 washed & filtered cleaner then both of the ferric tests & the ferric w/oxidized seemed to filter cleaner then the hot ferric

The bottom line being that when considering the low grade/yield material both the nitric & M44 did yield foils & by appearance very near equal

Pics are ; - starting material, nitric filter, M44 filter

Kurt

 

[kurtak]

More pics; - the sludge filtered from decanting the ferric & the metals that were left in the bottom of the ferric beakers

 

[kurtak]

Conclusion & Further Work Planned

My conclusion is that the M44 process is in fact very comparable to nitric when it comes to the speed for removing base metals to recover foils

However - it does have some drawbacks one being that unlike nitric you can't just start it & walk away to go do other things - it requires your full attention to work it

Also there is the chance of flopping (up setting) the chem balance in which case you will dissolve your gold - so this is not a process for the beginner refiner - you have to have a good deal of time under your belt working with reactions & a good understanding of what is going on with reactions that are taking place - there is a learning curve even for the experienced refiner - I would want to run it several times on small batches to fully grasp it before employing it on any large scale/batch

Its a bit messy due to spattering from the fizzing - ware your gloves & a long sleeve shirt & you might consider using a face shield - though I didn't find it necessary as you can make your additions & then step back to keep an eye on it between additions

Some advantages I see are that if you can't get nitric &/or have to pay an outrageous price for nitric - but have work you want to get done with the speed of nitric - then this is a possible alternative

The HCl & the sodium nitrate can both be gotten from your local hardware store - if they carry the Hi Yield brand fertilizer but don't have the sodium nitrate on the shelf they can order it for you - the ferric/ferrous chloride can be had from some of your own waste product so you can actually recycle some of your waste back into your processing system

Concerning fumes I did not see any noticeable Nox fumes - at least they were not detectable - certainly less then AR or nitric its self - mostly HCl fuming - nothing evident beyond that which we deal with in other processing - so normal safety procedure concerning fumes

Then there is the question of other material it can/could be used on besides just copper/brass pins - Jerry has posted a list of some other types of material he has used it on - the question being how well it works

Further Work To Be Done

I want to run this at least one more time on a better grade of foil yielding material

Also I want to try it on kovar - in particular I want to try it on the kovar removed from IC chip ash (which always drags bonding wire with it when removing it from the ash) --- in fact I "think" this might just be where this process has a real purpose to serve in the (home) refiners tool box

Also TO5's would be a good one to test it on but that one is low on the list as I normally don't even save them for processing so maybe only have a hand full hanging around the shop - will have to see what I might get out of the gaylord of CBs I just got in - but that's down :arrow: the road

Personal Comment

All in all I have to say that this was a very interesting & learning experience for me & I want to thank Jerry personally for sharing it with me in the first place & then I want to thank the forum for the opportunity to run it & present it as I did (you all kinda made it a challenge) --- I think this was one of the most fun projects I have worked on since becoming a member of this forum & maybe even ranks up in the top 10 of fun/challenging projects worked on in my life :mrgreen:

So thanks again to all of you - I have a great deal of respect for each & every one of you :!:

Kurt

 

[Anonymous]

Thanks Kurt and Jerry.

I've followed this through from the beginning and whether it's of use or not the best part of it all for me personally was the fact that it was suggested and tried.

Dismissing things out of hand without even realistically attempting them is at best counter-productive. Everything we already do was once untried and untested or has that little nugget of information been forgotten? 8) 8)

Thanks again.

ps - like Kurt I can already see another possible use for this and I'll do my own testing on it once my lab is commissioned.

Jon

 

[FrugalRefiner]

Thank you for following through and sharing your process Mod! Now that people know what it is, more members can test it and report their results. It might help them to know what problems may come up and how to avoid / control them. I'm sure you ran into some while you were developing the process.

Dave

 

[g_axelsson]

First question I would ask is if you tested the M44 solution with stannous?

Haven't seen any answer to this yet. I would suspect at least some gold to be dissolved.

Cathodic protection only works when the metals are in electrical contact. As soon as foils drop off the base metal the dissolving should start. This should be more intense at the end as there are less base metals left and when finished there should be no more base metals left to protect the gold.

Kurt, did you run the process to the end? How much gold did you recover in each beaker? Did the process complicate the final refining?

Göran

 

[Lou]

As long as some base metals are left behind and the surface is not passivated, the end result will be gold collecting on the base metals or else displacing them per EM series.

Lou

 

[g_axelsson]

There is a time while gold chloride is in solution between dissolving from suspended gold (foils, cemented mud) and cementing onto base metals. The gold ions have to get close enough to the base metal to cement onto the surface.
If the solution is filtered off while actively dissolving metals some gold should end up in the filtered off solution.

Göran

 

[Barren Realms 007]

First question I would ask is if you tested the M44 solution with stannous?

Haven't seen any answer to this yet. I would suspect at least some gold to be dissolved.

Cathodic protection only works when the metals are in electrical contact. As soon as foils drop off the base metal the dissolving should start. This should be more intense at the end as there are less base metals left and when finished there should be no more base metals left to protect the gold.

Kurt, did you run the process to the end? How much gold did you recover in each beaker? Did the process complicate the final refining?

Göran

Just as Lou said as long as there are base metals left there is not a problem because the gold will cement back out of the solution.


https://www.youtube.com/watch?v=w4W6PjEwRwQ

If you look at this other video of Mods you can see what happens when you have the solution saturated. When it cools down it clumps up and has to be reheated to get the base metals back into the solution. That's really not a problem if you want to run it this way because by this time the nitrates have been used up in the solution and you can heat the solution back up and thin it out by adding HCL. If you try to dilute it with water it creates another set of problems you have to deal with. But it does create filtering problems in the long run.

As Kurt said it is labor intensive the way they are documinting it to be done. They can eliminate some of that by doing their calculations on how much sodium nitrate they will need to dissolve the base metals and put in 90% of what is needed on the front end. Then they can let the solution run and have a set time frame on when they need to go look at the solution between additions of HCL, and having a set amount of HCL to add each time. They will need to be careful on the additions of HCL because the gold that cements out and settles can cause a boil over when they add their HCL, especially with the heat turned up so high on their solutions.

And of course tin creates it own nightmares when trying to filter the solutions. When he gets finished with a process and has it filtered if he would then take the solution and cement out the copper and wash it down clean and melt it and then set the copper up to be run in a copper sulfate cell he can recover any gold that may have been lost during the process.

I have found that it is just a better use of time to take a plastic 5 gallon bucket and process 1-3 lbs. of pins at a time using poor mans AR. Start it off in the afternoon and let it run it's course then go out the next morning and heat the solution up and denox it with sulfamic acid if necessary. You can set up 1,2,10 or 20 buckets like this and then deal with it the next day. And if you find a solution that will not filter well just don't filter it and go ahead and drop the gold out of the solution with copperas and deal with the contaminates on the second refine.

If you pay attention to what GSP has written in the past you will see where he says that he has had up to 20 buckets filtering at one time. You can get and WHOLE lot done when you are working with these amounts of solution at one time.

Kurt and Jerry I commend you for documenting this process so well and working so hard to bring it to the forefront of processing. However IMHO it is not a new process, and especially not one that someone new to refining should be trying to attempt.

Goran, It's really not a good idea to be trying to filter your solutions while they are still actively still dissolving base metals as you are well aware of. And as concentrated with base metals as they are running their solutions the gold is probably all going to cement out. The trick is collecting all of the gold that cements out in the bottom of your bucket or hoping that it is caught in your filter. But IMHO I hate dealing with cemented gold in filters, it just means that more solution you have to use to cover the filters to dissolve your gold on the second refine unless you incinerate them before you process it.

 

[g_axelsson]

Goran, It's really not a good idea to be trying to filter your solutions while they are still actively still dissolving base metals as you are well aware of. And as concentrated with base metals as they are running their solutions the gold is probably all going to cement out. The trick is collecting all of the gold that cements out in the bottom of your bucket or hoping that it is caught in your filter. But IMHO I hate dealing with cemented gold in filters, it just means that more solution you have to use to cover the filters to dissolve your gold on the second refine unless you incinerate them before you process it.

Yeah, I know, but if I'm not mistaken that is exactly what happened in the experiment as Kurt needed to abort before it was completed. It can be hard to notice any slow reaction still going on when the solution is as dark as it was.

As I see it, the experiment hasn't been finished yet. Does it start to put gold in solution when the base metals are used up? How to properly finish a run? Any problems with tin or other hard filtered substances after a completed run? How much gold was recovered with the various methods?

Göran

 

[Geo]

So metaphorically speaking, that the race is not to the swift, nor the battle to the strong.

 

[Barren Realms 007]

Goran, It's really not a good idea to be trying to filter your solutions while they are still actively still dissolving base metals as you are well aware of. And as concentrated with base metals as they are running their solutions the gold is probably all going to cement out. The trick is collecting all of the gold that cements out in the bottom of your bucket or hoping that it is caught in your filter. But IMHO I hate dealing with cemented gold in filters, it just means that more solution you have to use to cover the filters to dissolve your gold on the second refine unless you incinerate them before you process it.

Yeah, I know, but if I'm not mistaken that is exactly what happened in the experiment as Kurt needed to abort before it was completed. It can be hard to notice any slow reaction still going on when the solution is as dark as it was.

As I see it, the experiment hasn't been finished yet.

That looks to be correct. We will just have to wait and see what Kurt comes up with. If Kurt had an analytical scale he would be able to tell better that this process yields a little bit less than the other 3 processes.

Does it start to put gold in solution when the base metals are used up?

It will start to put gold into solution before all of the base metals are dissolved, especially with the high heat it is being run at. A lower heat setting would eliminate some of that possibility but over all some of the gold will start to dissolve into the solution and then it will cement back out on the base metals if left for an extended period of time and you will need to watch for a boil over when you continue to add the next addition of HCL to it. The higher the processing temperature the more of a possibility of a boil over when the next addition of HCL is added.

How to properly finish a run?

That will take some patience and because the solution is so saturated with copper there is the possibility that some of the gold particals will go through the filter until it closes up the pores on the filter and filters out the smaller particals.

Any problems with tin or other hard filtered substances after a completed run?

If there is a significant amount of tin on the material then yes it can cause problems filtering. I have had solutions that had so much tin that they wouldn't filter well and have had to abandon filtering and just drop the gold out of the solution.

How much gold was recovered with the various methods?

8) We shall see soon hopefully.

 

[Lou]

You know, I see a lot of mention here about just using nitric acid on pins.

While nitric often works fine (especially so with Au/Cu systems where tin is not present) and provides pretty much the best accountability, it is not at all acceptable NOR LEGAL IN THE UNITED STATES to just dump 50 lbs of pins in a drum and 20 gallons of nitric acid and let 'er rip.

Bear in mind that the federal limit for NOx, which are a hazardous air pollutant (HAP) is 10 lbs/day. Below that, it's considered a source so minor it is de minimis and therefore not regulated (though stipulations apply--namely that you better have your records together if you claim this). Also, different municipalities have different rules. The federal rules serve as the minimum guide.

So, copper dissolves in nitric acid in one of two ways--a pathway that makes NO which ultimately ends up as NO2 and one that just makes straight NO2:

3 Cu (s) + 8 HNO3 (aq) = 3 Cu(NO3)2 + 2 NO (g) + 4H2O (1)
1 Cu (s) + 4 HNO3 (aq) = 1 Cu(NO3)2 + 2 NO2 (g) + 2 H2O (2)

Reaction 1 occurs in dilute systems, typically below 3.9 M HNO3 (so called reagent, or azeotropic nitric acid is ~15.7-16 M).
Anyway, what does this mean? It means for every pound of copper digested (454 g/lb) / (63.55 g/mol Cu) X 2 mol NOx = 14.3 mol NOx per lb. As it ultimately ends up as NO2, that's how the emission factor should be calculated.
NO2 is 46.01 g/mol so 1.45 lbs of NOx per lb of copper dissolved.

That said, please don't dissolve more than 6.5 lbs of copper/day unless you have a permit to install and operate a fume scrubber or want to risk a fine and/or possible criminal sanctions!