removing casting investment

[abazabazoom]

Hi all,
im trying to get into refining for my small casting house.
alot of gold and silver waste are incorporated with casting investment,
does anyone know how the investment removing is done chemicaly or otherwise ?
ive done a test using an investment remover for 24 hours and had no results.

thanks in advance

Mosses

 

[rusty]

Hi all,
im trying to get into refining for my small casting house.
alot of gold and silver waste are incorporated with casting investment,
does anyone know how the investment removing is done chemicaly or otherwise ?
ive done a test using an investment remover for 24 hours and had no results.

thanks in advance

Mosses

What exactly did you expect the investment remover to accomplish after 24 hours in the ultrasonic cleaner. There will be no gold or silver values in your investment only in the casing sprue's, trees and polishing dust.

Regards
Rusty

 

[nickvc]

The investment powder will have some values in it but the cost of recovery can be more than they are worth, it might pay if you can concentrate the values, look at the mining section for ideas on how to do that,the only other way is to use hydrofloric which is highly dangerous and which I avoid.

 

[rusty]

The investment powder will have some values in it but the cost of recovery can be more than they are worth, it might pay if you can concentrate the values, look at the mining section for ideas on how to do that,the only other way is to use hydrofloric which is highly dangerous and which I avoid.

Assay first, this will determine if there are enough values to chase versus cost of extraction.

Regards
Rusty

 

[abazabazoom]

HI again,

thanks for repling,
It seems that my question was misunderstood.

i wasnt refering to refining casting investment but washing it from gold filings.

thanks again

moses

 

[seawolf]

If you have gold filings mixed in with investment powder HCL if I remember right should digest the powder without digesting the gold. To test I would put a few grams in a small beaker or test tube and add a little HCL then swirl to mix. Take care it might foam or have other reaction. If it does digest the powder then just good rinsing should concentrate the gold for refining.
Mark

 

[goldsilverpro]

This may help

 

[seawolf]

goldsilverpro You must have one whale of a library.
Mark

 

[rspearse]

I believe he is asking how to remove the investment from the casting. Of course, it depends on what investment compound you use. If it's something like Doc's from PM West or Talladium, they are rock hard and very difficult to remove. Hydrofluoric acid is one way to do it, but as the others will attest to, it's very dangerous. There is another, safer way that uses peroxide (I think), but I'll have to check into that.
Tell me, please, are you casting polymers from a 3d printer? And casting higher temp metals (like platinum)?

 

[nickvc]

It really depends on what exactly you describe as filings, if it's literally from a file i would just melt it with a little flux but if it's come from a wheel it will probably have carburundam dust included and that is extremely difficult to melt successfully, if that is the case then the best method is total dissolution using the methods outlined here on the forum.

 

[qst42know]

The document GSP provided a method on page 22 to mostly dissolve investment plaster. Overnight in ammonium carbonate, water wash, and then HCL.