First time electrolyzer de-plating

[FrugalEE]

I've given this some more thought and realized that any attempt to duty cycle the current will almost certainly result in more heating than a steady current. I say this based on experience with power supply design. I'm talking about a simple a 60 Hz supply where you have a transformer driving a full wave rectifier followed by a large bank of capacitors. If your transformer is designed for good regulation with tight coupling from primary to secondary your transformer currents will be in short bursts of high current. This causes excessive losses (I squared R) in the copper wire and excess heating. In my case I had to meet a Military specification that the copper winding temperatures would not exceed 40 degree C rise and that is pretty tough to do. I remember an early attempt to reduce heating by beefing up the transformer actually back fired and got hotter than the smaller version. What we had to do was to specify an amount of leakage reactance to be designed into the transformer which was done by winding it in a way that reduced coupling from primary to secondary windings. That reduced the current peaks and spread the currrent out over a longer duty cycle and the transformer then ran a lot cooler.

Unless for some strange reason your fluid resistance is not constant during the duration of a pulse you will produce less heating if you use the longest possible duty cycle. Note that I am only talking about heating effect here and not what happens chemically.

Another unrelated thought was to weigh your pins before and after deplating to get some idea of how much metal you put into solution. Someone earlier suggested cementing out copper from a sample.

Hope this helps,

FrugalEE



FrugalEE

 

[goldenchild]

The power source that I use is a simple old and I mean old Dayton battery charger. 120 AMP max load, 6V Hi/Low, 12V Hi/Low, Boost. The container I did use held about 3/4 of a liter or solution and I ran it on 12V Low with just a hot and ground. It has a built in amp meter and when the load drops I know the material is finished. It will deplate a pentium pro gold top in around 1 min. This container set in another container the held an ice bath. If I remember right around 75 pentiums could be done with a round of solution. Very simple setup.

Barren. Thanks for the tip on the copper tubing for the other thread. I will try it tonight. What you wrote here makes me wonder. Is there a hard and fast rule of when to empty your cell? I have a 1 liter cell that I have already deplated 5 pounds of well plated jewelry and its still working. I have noticed that it efficiently deplates for a shorter amount of time each time I use it. Im guessing thats because of all the gold and base metals floating around. But then I eventually add fresh acid and it gets going again. I guess as long as it keeps working and as long as the gold doesnt reach the cathode you are fine. I have a video of the starting cell that I will post tonight. Nothing special but has some excellent music :lol:

 

[adam_mizer]

Some changes of setup are due.
I have been in the garage with doors open for ventilations.
The wife came in and said she smelled some chemical in the air which for purposes of health I'm moving it all outside until the home made scrubber is devised. That may take me more time than I think to build a plastic encolsure and make the plastic ducting system and the water enclosure.
Outside seems the easiest for right now to complete the work that was started.

The auric chloride sat all night hopefully the chlorine gases of the mixture have diminished and I can do the SMB which leads me to devising a small vaccuum chamber to utilize my hvac pump.
This auric chloride is evident copper is present but not by doing a ammonia test on my wash which I would have liked to do but there is a slight green tint not very much and while washing the electrode water rinse and filtering it I viewed a nice heavenly light blue tint in the water.

Okay a couple of processes to go, brings me to: drop the gold but then wash it 2-3 times in luke-warm hcl I'm thinking to get the small amount of copper out.

I did happen to run 2 test batches last night of much larger pins, the pin size also allowed me to put 150 grams in for each batch.
1st batch at 14.5vdc, selected this voltage because I am guessing a 12v battery charger puts out more voltage to charge as an alternator would charge your battery in a vehicle system.
500hz was chosen at 5.1amp setting and the duty cycle of the 500hz set on automatic to maintain this 5.1amp current, well I'm going to forget this test fast as this caused the bath a very quick heating to run the single batch, time completed 17min. The CCPWM drops to actually 0.2a current on the display. Inspection of pins terrible as there was plating still left to be removed everywhere through-out this batch. Also note this is the first time I saw discolored or brown bubbles from the lead.

2nd batch 4khz at 6ampere, 10vdc, 16min run time 150grams large pins. No brown bubbles. Also all previous batches were done at 4khz with no brown bubbles or barely noticable. Temp rise was much slower, and the finished product was very good deplated pins unlike the previous batch. Duty started at 50% and rose to 100% as the current starts dropping before the batch is finished de-electroplating.

So far I have noticed that maintaining 4khz, voltage 10 or less, amperage 5-6 is giving good deplating results and keeps the heat down.

FrugalEE I can understand your heating issue but we are not talking about wire coils, we are talking about the effect of heat between the electrodes in an electrolyte. I have run and built hydrogen celles for 8 years and the last 3 spent very much of my spare time doing it and finally in the last year I started taking data measurements. Heating was a concern of mine since I started using PVC piping. Cell number, cell spacing, cell flow, CCPWM setting and voltage, all had an effect on the temperature curve.
In this case the CCPWM slowed down the heating of the electrolyte issue enough to notice that the cell could be driven for much longer periods of time before you would have to cool it.
From my long experiences with cell control and design I can see that this single cell deplating acid bath is of simalar design. There is an ionic exchange in the hydrogen cell of the electrolye and the more you understand how this exchange takes effect with all the controlling issues you start to zone into the quality of gas produced. Its this quality in the gas that is basically realigning the electrons of the atoms of the H and O particles in their groups.

The gray powder is interesting that maybe one day it will be figured out. It should be a metal residual salt wouldn't you think? Which one though!

 

[goldenchild]

Here's the vid. I decided to take the music out as it could be distracting. Good but distracting.

[youtube]http://www.youtube.com/watch?v=cCro6V_RsTo&feature=player_profilepage[/youtube]

 

[lazersteve]

Great video, thanks for the website plug also!

As promised here's the reply I typed up a few nights ago:

Yes thats it home made scrubber. A vacuum scrubber in my case.

I'm not experienced yet but by the looks of the material that was unplated it appears perfectly sound less the gold plating.
Will inspect it and try to siphon it off later this evening.
I'm curious to see what 610 grams of board edge pins, DB sockets, cable connectors etc... will produce in the end.

Adam,

The following comments are not meant to detract from what you are doing, I'm merely trying to give you a better understanding of what factors are important when using the cell verses which ones are more trivial. Please accept them in this light.

I admire your attention to detail as far as the temperature and electrical parameters of the stripping cell reaction is concerned, but frankly a few degrees Celsius or Fahrenheit and/or minor dc volts or amps variations of your cell will not go to drastically affect the final outcome. If it makes you feel better about getting the reaction 'just right', you can continuously monitor your cell temperature, amps, and volts parameters, but all of it will vary with each and every unique type of scrap you are running.

Think of the gold plated part(s) you are stripping as another unknown (perhaps the biggest) and you will see where I'm coming from. In your quote above you mentioned a particular weight of 'board edge pins, DB sockets, cable connectors, etc...', but you do not specify the manufacturer, year of manufacture, application, base metal, etc. These factors all will affect the yields as well as the results of the observations you are charting, maybe even more so than the temperature, voltage, and amperage. In fact the physical characteristics of the gold plated part may be the biggest contributing factor to the variations you measure and for this reason your values will always be different for each and every unique type of scrap.

In short the generic terms like cold, hot, and 12 v 10 A battery charger are more than accurate enough to get a cell operational and producing gold. If you need a more accurate assessment of the temperatures, then let me suggest these operating conditions for the hobbyist cell set up:

1. Wear goggles, protective gloves, and a good acid resistant apron. Start with your sulfuric acid at room temperature (20C). The sulfuric acid should be of 95% concentration or higher.

2. Use a standard 'manual' automotive charger with a built in analog amp meter (one with a moving needle) that is capable of delivering 12v DC @ 10 amps on a continuous basis. The automatic variety of chargers (with led bar graph amp meters) should not be used. The automatic types contain electronic circuits used to sense the battery condition and control the charging of batteries while protecting them and you from harm. These extra circuits don't 'play nice' (new technical term :lol: ) with the cell set up.

3. Attach a piece of lead to the negative lead of the charger and hang it from one side of your cell set up.

4. Attach the positive lead (copper alligator clip) of the charger to the part to be stripped, or to a copper basket arranged to hold smaller items in bulk. The size of your cell and consequently the basket size will limit the mass of small items you can strip in one run. Be sure the negative lead has an uninterrupted path to the items to be stripped. Imagine a line of sight (LOS) between the part(s) to be stripped and the negative lead. If this LOS is broken by the copper metal from the front edge of the basket, the basket will act as a shield (aka: farady shield) to the pins and slow the strip time and heat the acid. Once the gold is stripped, remove the part as soon as possible.

I have noticed that the longer a stripped (ie: gold is all removed) part stays in the electrolyte with voltage applied, the more the cell will heat. The energy of the charger is no longer being used to strip gold, instead it is being conducted to the negative lead and generating heat very quickly once the gold is removed. In a perfect world we could calculate the gold yielded from a stripped part by the amount of time required to strip the part in the cell and recording the amount of amps used. In the real world the electrons are conducted along various side paths in addition to being used to strip the gold and we as humans don't remove the part at the exact moment all of the gold is stripped, so the real number of amps consumed is a sum of all of the losses, plus the amps required to strip the gold.

5. Rinse the stripped part in water (or baking soda water) over a container sized as needed for your cell set up. I like to use a spray bottle of straight water, it's quick, conserves water, and the rinse water is always clean that touches the part(s). The rinse pot eventually accumulates a layer of black gold powder on the bottom after extended use followed by a settling period. This black powder is combined with the cell yields.

6. Dab the rinsed part onto a dry paper towel. I like paper towels because they can be burnt to recover any traces of gold in them. One paper towel goes a long way if folded properly and allowed to dry between cell runs. This step is very important to the life of your copper clips and basket. Be sure your clip/basket has most of the water removed from it before placing it back in the cell.

7. Repeat steps 4 through 6 until the cell gets hot to the touch. If you are using a thermometer to determine when your cell is hot, stop when the cell reaches 90C. A cell gets hot for several reasons:

A. Normal stripping of gold.
B. Leaving stripped parts in the electrolyte with the power applied after they have been stripped.
C. Adding water to the cell. Either via air, intentionally, or unintentionally.
D. Your cell is too small for the batch sizes you are running.
E. Shorting of the positive and negative electrodes.
F. Higher amperage flowing per second in a given volume of sulfuric acid.
G. Other factors

Notes:

A. Diluted sulfuric acid, especially when 'hot' (ie > 60C) will eat copper (and many other metals) quickly. Dilution can occur via rinse water trapped on the surface of the anode lead or from absorption through the air.

B. If you rinse your copper clips or basket and do not remove the excess rinse water from the copper before adding it back into the sulfuric acid cell, you are in effect placing your copper into diluted sulfuric acid and will experience a much shorter life cycle for these items. Drying your leads/basket between 'dip and rinse' cycles will greatly extend the life of these parts.

C. Parts must be fully exposed to the sulfuric acid in order for them to strip. Sounds obvious, but a large mass of pins will mechanically shield one another from exposure to the sulfuric acid and the pins on the bottom and inside of the pile will not strip completely or at all.

D. A cell is full and should be cleaned out when the sulfuric acid is saturated with black powder to the point where the powder short circuits the negative and positive leads of the cell when in normal operation. This shorting can occur on the bottom (most common) or on top of the electrolyte as floating blobs of gold and bubbles. Try to sink any floaters with a glass rod to prevent the build up of top floaters. Proper placement of the positive and negative leads can extend the time required between clean outs. The leads should be mounted so that they do not rest directly on the bottom of the cell. Let everything settle for 24 hours before you clean out the cell. You may find the sulfuric acid clears (straw colored to green brown) after the cell settles. This upper layer of acid can be carefully siphoned off for use in the next cell without any further treatment. The black sludge is treated as described in my Black Powder from the Cell post.

You may want to clean out your cell sooner if you want to determine yield data for the scrap in question or you are out of material to process and want to store the cell.

E. The greater the flow of amps in a cell, the greater the number of gold plated parts the cell can strip in the same amount of time. This heats the cell faster as well. The larger the volume of acid in the cell the longer it takes to heat up.


I'm interested in you CCPWM results, but I'm going to predict it will take longer to strip the same parts than with pure DC. The off cycles do not supply the electrons that do the work of stripping the gold atoms off of the part(s). Less electrons in a given time equals less gold stripped in that time.

Steve

 

[adam_mizer]

Great video Goldenchild, I really like the visual on the white bubbles and reaction real clean.

Excellent description Steve particularly where you point out 90c as the high point temperature and here I am worrying about 85-90f huge difference, 90c is a 194degree's farenhiet.
So you say at greater than 60c the cell acid can eat copper pretty good. Thats very good to know as 60c is 140f and gives a large temp span for cooking a lot of material.
That changes everything and here I am spinning my wheels.
Last batch I did with regular charger and current and it works just fine.

At least I took notes and tried a variety of settings with a duty pulse and had a bit of fun learning a bit on the way.
Right now I'm ready to trash-can the duty test but one thing I trully believe I was able to keep the temperature down. It seemed 50-60% duty pulse and 5.0-5.5 ampere's current and less than 12volts worked the best to keep the temperature curve down, but it appears the stripping time took much longer.

Now on my next batch after this one will be done on the straight charger.

Again I say "Steve excellent description", I bet many people were waiting to have such a good description of the cell and usage detail. It would be a very good idea for you to make that DVD.
I would like to ask one more thing:
I'm going to settle the gold powder out of the auric chloride but will have a tiny amount of copper to deal with. Guessing I will use HCl to remove this copper and to get a timely responce of the HCl it should be warmed up. Right now my ambient garage temp is in the mid 40's. Question is how far to warm the HCl in order for it not to eat the gold powder?
Wow another temperature detail.

Thanks very much I just love those detailed posts you guys are great in my book.

 

[goldenchild]

Great video, thanks for the website plug also!
Steve

Thanks

Great video Goldenchild, I really like the visual on the white bubbles and reaction real clean.

Theres nothing like a fresh cell with pure white bubbles. I almost hate to get all that black sludge in there. Almost. :lol:

I'm going to settle the gold powder out of the auric chloride but will have a tiny amount of copper to deal with. Guessing I will use HCl to remove this copper and to get a timely responce of the HCl it should be warmed up. Right now my ambient garage temp is in the mid 40's. Question is how far to warm the HCl in order for it not to eat the gold powder?

No need to worry about HCL dissolving the gold. It cant on its own. Heat the HCL as much as needed but try not to boil it. In a finely divided state it wont take much heat at all to get rid of the copper.

 

[adam_mizer]

Thanks GC for the HCl info really needed it as it helps in understanding the temperatures which I worry about for some dumbfounded reason.

Anyways I don't know if I need worry about the copper but I will rinse in HCl regardless but for some reason the Auric Chloride I processed, took the powder out of it and the remainder has the light green tint still in it. Tested with stanous and its blank for gold.
I'm confounded, the beginner I am at the fact there is still a tint in the processed auric chloride. On top of that I added more SMB just to be sure, but notta thing happened.

 

[lazersteve]

Looks like you got it all to me.

Lots of metals will give a light green tint, notably some valences of nickel, zinc, and iron.

You did very well from the looks of the gold powder.

Steve

 

[goldenchild]

Yes. If this was your first processing of cell recovered gold with AR you will almost certainly not get a perfectly yellow gold chloride or end up with a crystal clear waste. I bet you would if you refined your resulting powders again :mrgreen:

 

[adam_mizer]

Okay here are 2 products, not finished yet because I need to further process the powder if possible.
2nd auric chloride was washed/rinsed better than first time.
2nd auric chloride, dried powder on left.
1st run dry powder on right.
Now there are differences and I'm thinking the first run could take a warm acid bath. Does Warm/hot hcl remove some stuff maybe copper/tin/lead?

Thanks I appreciate your feedback.

 

[Barren Realms 007]

A warm or hot acid bath will do better than a cold one.

 

[adam_mizer]

Okay thanks Barren, on my third batch I did a hot HCl rinse this time and I'll see what color that is soon.

Looking at Steve's melt video his powder is like the one I have on the left with a little red tint.
Here'sthe funny thing the powder on the right although looks like maybe 1/2 the volume of the one on left is only 0.4 gram less in weight.
The powder on the right actually weighs more if it had the same volume.
On right was 1970's-90's mixed pins. On left was card edge foils.
Will see what color the rest of my pin stock will look like with the HCl hot/rinse.

 

[adam_mizer]

Well here's my 3rd run and some summary for beginners.

First off let me say thank you to this forum and its members, without the help and instruction I couldn't get started to do this.
This is no easy task, safety and amount of carefull work with acids, chemicals, wash/rinse and filter. Then deal with wastes!

Here's a direct run down, I have posted types of pins although in my first pictures you did not see the large pins and tiny spring and contact pin. The test pins were gorgeous from pretty large to very small. Even 1/2LB of tiny gold springs and counter sink pin very small beutifully plated like looking at very bright pure yellow/gold. The pins totalled approximately 4LB's material.
The card edge fingers were cut very tight meaning to the actual edge of gold finger, no waste left behind and totalled 20oz's of material.

1st run heavily filtered/washed with distilled several several times.
2nd run edge fingers filtered/washed many times.
3rd run filtered/washed in HOT HCl, the black powder and after dropping, hot HCl on the gold powder. This is the color I believe I should try to achieve. Almost pure as I have read here in the forum of Ultra Pure Purity methods.
The Hot HCl wash/rinse is very good as it shows the differences in my powder picture, from water rinse to acid rinse.

I may have just a little not amounting to much black powders in filters saved.
4LB's nice pins = approximately 9grams gold.
20oz's edge fingers = less than 3.2grams gold after I wash/rinse in HCl.

All I can say is its an interesting experience and a fun addicting hobby, learning and using the methods of LazerSteve. I hope to learn more about these and other processes.
The guy's here are great and the help is phenominal.

 

[Barren Realms 007]

I might suggest breaking up the clumps if there are any when you are doing your cleaning. Looking nice tho.

 

[goldenchild]

I see a nice 12 gram button in your future. 8)

 

[adam_mizer]

Cleaned up that one red-tinted powder batch just a little with hot HCl and it was added to the 1st semi-dark batch.
Still a little bit dark-tint though but better as red-tint is reduced and weight reduced 0.2gm.
Cleaned up some left overs from that run and got 0.4gm added in so all is working in the plus.

Also have noticed working the left overs just how much nickel there is in this stuff. It comes out easily and its got to be that white/gray powder residual.

Working on some of my scrap materials, back to doing the AP method.
There's a batch that sat in there for several days plus using old AP and some fresh. Looks like gallon and half now.
Appears very dark now and I have cleaned the batch out and washed off the small cards in seperate container and they still need to sit in the AP to finish up.
Have been adding into the bucket odd cards a couple cpu's and some edge fingers as I go along.
While cleaning I have noticed some full tracings have come off the old scopes and communication test cards but do still have some copper attached to the foils, also many little cards I have the gold plate has been coming off and its funny that some of the copper is still attached to the small card. (Somehow I think some of this is due to the variations of nickel plate).
I figure the AP needs freshening as its filling with copper, its effects have slowed down consideraby.

You guys have stated using a air bubbler device for freshening up.
Trying to use stuff I have here at my disposal, I have come up with a small ozone pump. The kind they would use on a small jacuzzi tub.
I'm wondering what would be the effect on the AP using the ozone pump as it introduces o3 into the mix.

Anybody know if the reaction of AP and o3 bubbling in would be okay?

 

[lazersteve]

Ozone (O3) is a very powerful oxidizer and will surely put some of your gold in solution. Oxygen (O2) is a better choice. I've posted links to several chemical variations of the acid peroxide (copper chloride etchant) reaction.

Here's a link with a reference:

Acid Peroxide and Ozone

and one on copper chloride etchant replenishing:

Replenish Acid Peroxide


Steve

 

[adam_mizer]

Your document "copper chloride etchant" at your site "http://goldrecovery.us/" is very informative for the AP process. Just what the doctor ordered!

Can't believe I didn't read it until now.
But as a begginer there is very much material to read and only a little of it needed to perform the goal of understanding those neccessary processes needed to work the material I have acquired. The choice e-scrap for the "LazerSteve methods" how about that.

I'll have to read all those doc's/pdf's you posted Steve in due time.
Thanks for all that stuff, its amazing what starts sticking in my mind as I am understanding the process.
I didn't take chemistry in school so I have a very hard time grasping at the way it works when a chemical is made into a group of chemicals.
Is there a basic document how this joins together the molecular formulas so a layman could understand?

 

[lazersteve]

Adam,

Unfortunately 'layman's chemistry' is sort of an oxymoron as chemistry has many specialized terms, mathematics, and shorthand to learn, which goes beyond most laymen. Hokes book is the closest thing to a layman's guide to refining that you will find. Chemistry is one of those things that takes time and repetition to learn, but once the light goes off, things become very clear. Math is also a big part of chemistry, this is one of the biggest hurdles people have with learning chemistry, linking the numbers to the symbols.

As you are starting to realize, the chemical processes for gold are basically all the same, it's just a matter of deciding what the best process is for your type of gold scrap.

I feel the key to processing any e-scrap is to know the physical qualities of the scrap you are dealing with. Once you know the composition of your scrap, you can quickly choose the right chemicals and reaction conditions to dissolve the values or base metals.

Steve