Electrochemistry Sulfuric acid stripping cell PSU

[BAMGOLD]

I'm new to this so bare with me here..

I have 4 ways of applying power, and am wanting to know what has been tested to work the most efficient.

1 - Phase Angle control of AC Voltage ran through a Bridge Rectifier, or Single Diode depending on amount of current needed
2 - Burst Fire control of AC Voltage ran through a Bridge Rectifier, or Single Diode depending on amount of current needed
3 - PWM DC Voltage
4 - Straight DC Voltage


Now you may be saying, well what's the difference between 1-3, well they are all different in that the amount of current and how it "hits" and duration are all different, and the difference could be miniscule, but as I haven't done this I don't know. Also 1 & 2 will be 60hz, but I can go higher with more work, these will be partial sign waves, so it's not just ON and OFF. PWM can be *basically* any hertz, but it's ON and OFF, ON and OFF, not gradual. And of course Straight DC Voltage can be any Voltage and it's just ON all the time, examples are *DUMB* Battery Chargers, Battery, Cell Phone Charger *I haven't look with my Oscope at a cell phone charger, but if it's not straight DC a simple Capacitor will overcome this, this would also work to change any sign waves we would be dealing with if needed to tweak them in the other applications.*

Thoughts?

 

[Lino1406]

Any one of these has the 25A capacity, which
looks basic?

 

[BAMGOLD]

Any one of these has the 25A capacity, which
looks basic?

I can make any of the handle 25amps.

Basic would be Straight Direct Current, I will keep reading as to which Voltage to use.

 

[Dlog Renim]

i do not know if that can help you..

most people use car battery charger (the non-intelligent one with s needle gauge)

i did a cell with a computer power supply.. mine say: Max 30amp on 12v ... so that is what i use..

 

[butcher]

Here are my thoughts,
A normally full wave rectified DC current would be my choice for most operations, with the ability to control voltage and current will normally be all that is needed, the power supply should be large enough to handle the load, and not overheat, also short circuit protection should be used, meters are nice to be able to monitor cells and power supply condition.

For some special applications a direct current with short burst of reverse polarity, can come in handy, like for removing silver chloride crust on an anode.

Or for some special applications a Pulse width modulated direct current, I use this for making my colloidal silver.

Power supply can easily be built with a just a little knowledge in electronics, from scrap materials most of us part out, many of the electronic scrap may already have a power supply that can easily be used with a little modification, or a variac (variable transformer) and a battery charger some meters and a series light bulb can make a decent power supply for most applications we use.

 

[BAMGOLD]

Here are my thoughts,
A normally full wave rectified DC current would be my choice for most operations, with the ability to control voltage and current will normally be all that is needed, the power supply should be large enough to handle the load, and not overheat, also short circuit protection should be used, meters are nice to be able to monitor cells and power supply condition.

For some special applications a direct current with short burst of reverse polarity, can come in handy, like for removing silver chloride crust on an anode.

Or for some special applications a Pulse width modulated direct current, I use this for making my colloidal silver.

Power supply can easily be built with a just a little knowledge in electronics, from scrap materials most of us part out, many of the electronic scrap may already have a power supply that can easily be used with a little modification, or a variac (variable transformer) and a battery charger some meters and a series light bulb can make a decent power supply for most applications we use.

Full Wave Rectified DC Current looks like this MMMMMMM, not ----------, if you want ------ you will need a Capacitor in the circuit. So which waveform would you like best I guess is my question more than anything...?

I own one of these to monitor everything (from my old wind turbine/solar setup I sold) http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10080

I don't have any issues with electronics or electricity, I'm just trying to figure out what is best as I have many options on what to build.

I want the best of the best for this, and if people haven't played with it enough to know, or are just happy with what they have, then I guess i have alot of experimenting to do.

 

[FrugalRefiner]

BAMGOLD,
I have to adit when I read your initial post it was totally over my head. I have always struggled with electronics. So I read your post with interest and have been following this thread to see if I could learn something.

But as I look back over it now, maybe the members who do understand this better than I aren't sure what you're asking about.

The title of the thread is "Gold Cell Power Supply". This can mean a number of things. There are gold deplating cells (sulfuric acid stripping cell), Wohlwill parting cells, karat gold cells (fizzer cell), etc. Each has its own requirements.

Perhaps if you can provide a little more detail about the material you want to refine and the process you're considering other members can provide a little more guidance. I suspect I'm not the only one who can't tell my "MMMMMMM" from my "----------" , but I also know of a few members who can.

Dave

 

[publius]

Dave,

What he is referring to is the conversion of the (AC) sine wave that starts at O Volts, rises to its highest + voltage (say 120 Volts) drops through 0 Volts then descends to its lowest - voltage the returns to 0 Volts to repeat the cycle to DC. One way is to clip the negative side of the sine wave. Hence the MMMM. That is DC rectified (if I recall correctly). Another way is to Flip the negative side of the sine wave. The capacitor stores the power from the first clipped portion of the sine wave (multiplying by -1) and puts it in between the two positive peaks making _____, in theory. In practice there are still sections of cycle that drop to 0 Volts however briefly.

That is one reason why I was asking about setting up cells with a battery rather than a power supply...

 

[BAMGOLD]

Can a Mod change the title to - "sulfuric acid stripping cell PSU" - Thanks for the suggestion, and thanks to the Mod who changes it.

 

[publius]

Can a Mod change the title to - "sulfuric acid stripping cell PSU" - Thanks for the suggestion, and thanks to the Mod who changes it.

I think if you click the edit button, you can also edit the title... (I think you can...)

 

[BAMGOLD]

Dave,

What he is referring to is the conversion of the (AC) sine wave that starts at O Volts, rises to its highest + voltage (say 120 Volts) drops through 0 Volts then descends to its lowest - voltage the returns to 0 Volts to repeat the cycle to DC. One way is to clip the negative side of the sine wave. Hence the MMMM. That is DC rectified (if I recall correctly). Another way is to Flip the negative side of the sine wave. The capacitor stores the power from the first clipped portion of the sine wave (multiplying by -1) and puts it in between the two positive peaks making _____, in theory. In practice there are still sections of cycle that drop to 0 Volts however briefly.

That is one reason why I was asking about setting up cells with a battery rather than a power supply...

Correct.. kind of.

AC in your wall (in the USA) is actually up to around 160volts, but a "usable" voltage is 120-110VAC. (usable voltage is known as RMS "root mean squared")
Clipping the top side only is just a single diode, well depends on the way you put the diode... you now make... n n n n n n (see the spaces, they use to be negative, but no longer "exist")
If you flip the negative side to the positive side, you now have mmmmm or nnnnn either/or same thing, the "SPACE" from before is now Positive, doubling your useable voltage.
The capacitor is used to fill in the gaps between the mmm or nnnn however you want to look at it. which in turn makes a straight line.. _________ (I used ---- before, I didn't hit the shift key on my keyboard, sorry)
As you describe the voltage dropping to zero for a split second, well... that all depends on the capacitance used.. 1uF or 1F... depending on what you all choose to be the best method I have any capacitor needed to create any sign wave needed...


To simplify this...

Do you want to take off 60% gold, then add 40% gold
Do you want to take off "some" gold in a split second, let the acid cool for 2? split seconds, then take off for another split second, repeat...
Do you want to take of "some" gold for a "little bit" then let the acid cool for a "split second" (notice less cooling) then repeat..
Do you want to take off 100%gold, then... nothing, just keep taking gold off

If this makes sense, great, if not, that's cool, learn with "us"

If I'm over thinking this, let me know, I'm almost certianly sure I am, but really... you never know... depending on the answer found at the end of this thread, we may be at just putting a single 10amp diode on the HOT wire of a power cord we stole off an old alarm clock and shoving it in our solution. (If you follow this, that would make a "n n n n" wave form, basically depleting extremely fast (as we are using utility voltage) for 50% of the time, and cooling for 50% of the time.

:?:

 

[BAMGOLD]

Can a Mod change the title to - "sulfuric acid stripping cell PSU" - Thanks for the suggestion, and thanks to the Mod who changes it.

I think if you click the edit button, you can also edit the title... (I think you can...)

You were right, every other forum I'm on, it will only change the "title of my reply" and not the actual "thread title"... cool... good to know! :mrgreen:

 

[publius]

Bamgold,

I am drawing off my high school (1973 grad) science class and a calculus class I had 10 years ago. Thank you for correcting me. I learned something! 8)

 

[BAMGOLD]

I think I can shorten this even more...

Do we want to de-plate QUICKLY and HEAT the solution
Do we want to de-plate MEDIUM? lol and Warm the solution
Do we want to de-plate SLOWLY and COOL the solution (we won't cool, but it will stay cool(er))

 

[FrugalRefiner]

Now that I can answer - at least in part. You don't really want to heat a stripping cell unless you have a SAFE way to dissipate the heat. As the temperature of the sulfuric acid rises it begins to attack the base metals more aggressively than when cool. It will contaminate your gold and foul the electrolyte.

By a SAFE way to dissipate heat, I mean something that does not involve ice baths or cold water.

Dave

 

[BAMGOLD]

I've read that about the heat attacking base metals, but also read about ways to cool it.

I'm looking for a scientific window into what is happening and why one method would work better than another, if possible...

If cooler is the way we want to do this (and application of voltage/current doesn't matter *AS MUCH* as temp), I may wire up an Arduino to a SSR with a battery and charger as the line voltage through the SSR, the reason for the Battery AND Charger is to buffer the wave to make sure it's ACTUAL DC Voltage, even tho the Arduino will turn it into PWM, I may end up with a 50% Duty Cycle at first, this should work HALF as fast as a normal battery would, but allow the solution to cool faster/heat slower, and be able to control the temp easier with a water bath, or possibly build some sort of Aluminum Heatsink with a fan?

There are a few ways to do this, but I have an Arduino and SSR's... You could go 555 Timer route, or other ways..

 

[FrugalRefiner]

Once again, I am lost on the electronic discussions, but I will say again, a water bath is NOT a good idea. Sulfuric acid is the poster child for the adage of never adding water to acid. It is highly exothermic. It can boil, sputter, cause steam explosions and otherwise spew sulfuric acid around your work area and on to you. Definitely NOT what we want for you.

Above all, be safe in everything you do. No amount of gold is worth your health, your sight, or your life. Learn how to work safely first, then tweak the details to your heart's content.

Dave

 

[Geo]

another safety concern i dont see mentioned much is to always turn off the current before you disconnect the leads. the two gases produced is hydrogen and oxygen. one spark can make a bubble explode sending drops of sulfuric everywhere. im speaking from experience. it happened to me with the first cell i made. i was actually moving the lead to different parts of the anode basket for a better connection and it sparked. next thing i knew, there was a loud pop like a firecracker went off and acid was every where. of course i lost a good apron on that one, but thank god i was wearing goggles and gloves.

 

[Golddigger Greg]

, or a variac (variable transformer) and a battery charger some meters and a series light bulb can make a decent power supply for most applications we use.

Would a 10amp be adequate? The reason I ask is I found a used pair available for what I think is a reasonable price. My cell is a ways down the road, but I'm always looking to pick up gear that I'll use eventually while I can find it.

 

[butcher]

Golddigger Greg,
If we are discussing a gold stripping cell using concentrated sulfuric acid, 10 amp battery charger will be large enough, as long as you build your cell similar in size to those you will see in the forum.

BAMGOLD,
As far as the rectified DC power supply, half wave rectified or full wave rectified DC current would both work even without filtering the DC output with a filter capacitor to smooth the ripple voltage, (you may or may not notice a very slight difference in time it would take to de-plate an object when using full wave rectified DC (four diode bridge which uses both halves of the AC sine wave to form a direct current voltage), verses the time of de-plating using half wave rectified DC voltage (one diode, using only the positive half of the AC sine wave as your DC source), I also do not think you would notice much temperature difference of the electrolyte in any of these DC sources (it would be very slight in my opinion, the electrolyte solution would not have time to cool down between the current pulses), and as long as the polarity of the DC was only the positive half of the sine wave no gold would plate back at the Anode (as would be the case if we used AC voltage as our power supply), the filter capacitor (A high microfarad capacitor) to smooth the DC output of your full wave rectified DC output to create a relatively smooth flat line DC voltage, is not that important in this application of de-plating gold from the anode materials, (we would not necessarily need a real smooth flat line DC in this application of our power supply), (although I use my power supplies for several other applications so I usually do filter mine), also we do not need anything fancy here like pulse width modulation or burst of reversal of current.
I think you are just over thinking this process.

Now if we were using the power supply for different applications, making colloidial silver or gold solutions, or like trying to grow a certain type or size of crystals in a silver cell, or de-plating gold from karat gold in a saturated salt cell with a membrane, or making a very high purity of gold in a wohlwill cell, then we may choose to get a little fancier with our power supply source.

If you wish to use your electronic skill to cool your gold stripping cell consider useing pelter juctions to cool them, you could then turn this pelter juction over and use it to heat a solution in another process in your lab.