Yes, it will only cement the more noble metals.
When In Doubt, Cement It Out _cementation_
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Ag and Au, I'm assuming you're referring to the reactivity series I included in my first post. As I mentioned there, it only contains the more common metals we most often deal with; silver, mercury, palladium, platinum, and gold.
There are of course other noble metals like iridium, rhodium, ruthenium, etc. and some other metals like titanium, tellurium, etc. that could cement if they happen to be in your solution, but most of us don't typically deal with these.
Dave
There are of course other noble metals like iridium, rhodium, ruthenium, etc. and some other metals like titanium, tellurium, etc. that could cement if they happen to be in your solution, but most of us don't typically deal with these.
Dave
Yes and understood. I guess I am foolishly "hung-up" with the word "precipitant" versus the word "cementation". When we use SMB after AR, we selectively precipitate (only the gold) onto "nothing" (lol). I guess what I am asking is: are they both doing the same thing chemically, except that the "copper" is broader in scope?
Martijn
Well-known member
Basically yes, you reduce a lesser reactive element with a more reactive element.
Some are pretty selective some are broader, like you say.
Copper reduces all lesser reactive metals from solution. Those are only a few and regarded as precious, that's why we use copper and not iron, zinc or aluminum for cementing pm's.
It's a game of exchanging electrons.
An element has it's protons and electrons in balance, when there is an electron added or taken away, it becomes an ion, and is in a state of oxidation. This makes bonding to other ions possible, making a compound.
The compound can be broken by a reducing agent which is able to donate an electron.
Some are pretty selective some are broader, like you say.
Copper reduces all lesser reactive metals from solution. Those are only a few and regarded as precious, that's why we use copper and not iron, zinc or aluminum for cementing pm's.
It's a game of exchanging electrons.
An element has it's protons and electrons in balance, when there is an electron added or taken away, it becomes an ion, and is in a state of oxidation. This makes bonding to other ions possible, making a compound.
The compound can be broken by a reducing agent which is able to donate an electron.
Outstanding. Thank you for the High School chemistry refresher.
Martijn
Well-known member
The silver nitrate electrolyte will indeed be made with HNO3.
There is no other acid for this type of cell as far as i know.
Look in the library for processes.
Could you in theory, add an extremely hot, saturated solution of copper dissolved in HCL/H2O2?
(I think) after mixing the solutions, agitation with a magnetic stirrer would cause copper to begin to precipitate out, upon which it would displace anything less reactive than it from the stockpot solution. Somehow I feel like this would be a more efficient reaction, and would allow for cementation of smaller particles.
(I think) after mixing the solutions, agitation with a magnetic stirrer would cause copper to begin to precipitate out, upon which it would displace anything less reactive than it from the stockpot solution. Somehow I feel like this would be a more efficient reaction, and would allow for cementation of smaller particles.
HCl and silver solution like silver nitrate will make silver chlorate , different than cementation , edited for clarity
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But won’t dissolved chlorides of metals of higher solubility come out as crystals?
They wouldn’t be in the metallic state, but since I’m going to redissolve them anyways, they would contain the PGMs, and concentration was my goal of the cementation process. In theory, this process would target smaller particles, since chloride compounds are smaller and more reactive than solid metals.
Regardless, I’m adding this to my list of future experiments. I’ll post results someday
Crystallizing happens when the solution gets too saturated to hold the salts in solution.
And they will crystalize as salts of their respective species.
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Size do not matter, valence and electro reactivity do.They wouldn’t be in the metallic state, but since I’m going to redissolve them anyways, they would contain the PGMs, and concentration was my goal of the cementation process. In theory, this process would target smaller particles, since chloride compounds are smaller and more reactive than solid metals.
Regardless, I’m adding this to my list of future experiments. I’ll post results someday
Right. But the least soluble compounds will crystallize first.
I just learned that fractional crystallization was a thing, like five minutes ago. I was looking for sources trying to explain what I meant, and apparently there’s a real process behind it already. Oh boy
.Valence of compounds in the nanometer range is directly affected by the visible light spectrum. That’s why crystals can grow in the dark, as transparent “glass like” structures.
You can literally change certain compound's valence states, by exposing them to light. And now, we’re entering the theories of quantum physics, where my knowledge hits the wall of a shit brickhouse
From Wikipedia (bad source I know…but Im intrigued, since I love to avoid applying heat to unknown substances)
“Fractional crystallization has various advantages over other separation technologies. First of all, it makes the purification of close boilers possible. This allows for very high purities even for challenging components. Furthermore, because of the lower operating temperature, the thermal stress applied to the product is very low. This is in particular relevant for products that would otherwise oligomerize or degrade. Next, fractional crystallization is usually an inherently safe technology, because it operates at low pressures and low temperatures. Also, it does not use any solvents and is emission-free. Finally, since the latent heat of solidification is 3–6x lower than the heat of evaporation, the energy consumption is – in comparison to distillation – much lower”
This is crazy.
I want to seperate PGMs, which have very high melting points. Check this out…
“The static crystallizer allows crystals to grow from a stagnant melt, making it a versatile and robust technology. It can purify highly challenging products, including those with most challenging properties, such as high viscosities and high or low melting points” -Wikipedia
I know it’s Wikipedia, so albeit, an “unreliable source”. But that’s not always so.
My goal is to seperate metals is extremely high melting points. Why melt at insane temperatures, when in theory…you can freeze at relatively high temperatures?
Crystallization is a way to separate salts, not very efficient outside lab environments and it still will be salts.
Alloys are not separated in metallic state.
You need to dissolve it or parts of it, and then one have the option to separate by any suitable property available.
Crystallisation is one, but takes a long time and are very impractical with respect to sorting out the different crystals.
Edit to add:
Fractional crystallization is not suited where the components are mutually acting as solvents for each others, as metals in alloys do.
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