99.5%? Is it possible?

[HAuCl4]

Maybe I didn't put my idea across correctly Barren:

A fiberglass cloth filter (that can be leached). Pass the liquid once, and the coarse particles stay, the fines some stay some get through. Pass it again, and the previously trapped particles act like a filter now, etc.

Maybe waiting is better. I do not know. What's the typical waiting time?.

A vibrating tank is another alternative, a centrifugal filter yet another, but trying to keep it simple.

 

[Barren Realms 007]

Maybe I didn't put my idea across correctly Barren:

A fiberglass cloth filter (that can be leached). Pass the liquid once, and the coarse particles stay, the fines some stay some get through. Pass it again, and the previously trapped particles act like a filter now, etc.

Maybe waiting is better. I do not know. What's the typical waiting time?.

A vibrating tank is another alternative, a centrifugal filter yet another, but trying to keep it simple.

That sounds better to use a fiberglass filter rather than a sand/rock filter.

There is no typical waiting time, it all depends on your solution and what you have in it. And how much paitence you have.

A vibration system does help. I had 3 gals or solution at 10:00 and added SMB to it. It had some floaters in it at 12:00 and I put it on my vibrating table(my outside A/c unit) and at 2:00 No more floaters and it is siphoned off with about 1/2 oz of solids. I will let this set for a while and siphone it off again later.

 

[HAuCl4]

I have a question about settling time and any losses from colloidal gold suspended in the water. One time bottleneck I see, is the Gold settling time. If it takes a day or more for the fines to settle out, that would be a significant bottleneck it the process. You can filter the water with a sub-micron filter but if you do it too soon, the filter will clog and the process will slow to a crawl again. It could take weeks or months for the finest particles to settle out. I've found that a few drops of acid in 4 liters of water speeds things up a lot, but it still takes time, and time is money.

If one could manage to use little enough water for the atomization (recirculate it?), there would be no need to filter at all, just put in the reactor as is, add the hot HCL , start to stir and feed the NaClO3 as solid. :idea:

Or just atomize into the cold HCL and heat it up at the same time!. I.e.: Use the HCL instead of water, to atomize :idea: :idea:

 

[4metals]

Most of the metal settles within 15 minutes, in a 3000 ounce pour about 2 ounce of fine are adrift in the water. For tight production schedules, process the 2998 ounces which have settled and the balance has settled within 24 hours so it can go in the next lot.

As far as letting the HCl heat up from the reaction, bad move. The sodium chlorate would gas off the Cl2 and not do as much work as if the acid was warm. Remember the molecules are dancin' and jigglin' when they are warm so they're more reactive.

 

[Irons]

Most of the metal settles within 15 minutes, in a 3000 ounce pour about 2 ounce of fine are adrift in the water. For tight production schedules, process the 2998 ounces which have settled and the balance has settled within 24 hours so it can go in the next lot.

As far as letting the HCl heat up from the reaction, bad move. The sodium chlorate would gas off the Cl2 and not do as much work as if the acid was warm. Remember the molecules are dancin' and jigglin' when they are warm so they're more reactive.

The Cl2 may be dancin' right out of the leach if it gets too warm. :mrgreen:

 

[goldenchild]

I think the purity and volume of the container also have alot to do with the settling time. If you look at my "gold buds" in the post "so pretty" you will see that there are 43 grams of high purity gold there. I precipitated it after twice refining in a maxwell house coffee container(the kind with the ez grip rubber coated top). No exageration... I added 45 grams of SMB dry, it foamed vigorously and all the gold was settled in about 30 secs.

 

[Barren Realms 007]

I think the purity and volume of the container also have alot to do with the settling time. If you look at my "gold buds" in the post "so pretty" you will see that there are 43 grams of high purity gold there. I precipitated it after twice refining in a maxwell house coffee container(the kind with the ez grip rubber coated top). No exageration... I added 45 grams of SMB dry, it foamed vigorously and all the gold was settled in about 30 secs.

Was your solution warm whn you added the SMB to it. Cooling it down seems to help. Not as much gas goes poof up in mid air. Who is to say you are not loosing gold in those bubbles? 8)

 

[4metals]

There is a world of difference between being warm when the metal is being digested and being warm when it is being dropped. I always drop gold from cold acid, the colder the better, the cold acid drops all of its silver so it can be filtered out before dropping.

The only digestion I can think of that is better with cold acid is to separate gold from platinum, the gold will digest but the platinum will be much less soluble.

The settling I spoke of above is strictly due to the small size of the atomized karat material which is in water, not even digested yet.

 

[Oz]

I put my gold chloride solutions in the freezer to precipitate my silver chloride, as the double dilution with water creates so much unnecessary waste. The added benefit is that if I filter quickly the solution is still cold when I go to precipitate, greatly increasing the solubility of SO2. This may be more important to me than some as I add my SMB dry. If you are lacking dedicated freezer space or are just in a hurry, ice cubes do wonders.

Empirically it seems that 32F or lower is every bit as effective as dilution with water X2 at room temperature. Does anyone have access to solubility charts for silver chloride that could confirm my observations?

For those that have never chilled auric chloride, when your solution is cold, dry SMB just drops to the bottom of your beaker before it reacts and gives off no wasted SO2 bubbles for you to breath until near the endpoint of the reaction. If you keep it cool (the reaction is exothermic) you can reach the endpoint without dispelling noxious SO2 gas and still have complete precipitations as long as you do not add SMB/SO2 gas too rapidly.

 

[HAuCl4]

Most of the metal settles within 15 minutes, in a 3000 ounce pour about 2 ounce of fine are adrift in the water. For tight production schedules, process the 2998 ounces which have settled and the balance has settled within 24 hours so it can go in the next lot.

As far as letting the HCl heat up from the reaction, bad move. The sodium chlorate would gas off the Cl2 and not do as much work as if the acid was warm. Remember the molecules are dancin' and jigglin' when they are warm so they're more reactive.

People would be better served if they heed the words of 4metals as the guy actually DOING it, as opposed to my wild speculative ideas POSTING on how it COULD be done differently. 8)

I keep thinking that properly washing and filtering the AgCl is the lengthiest and hardest part. How long does it actually take 4metals?.

 

[4metals]

Silver chlorides from a 3000 oz batch, about 240 ounces of silver expected, do not slow things down much. The chlorides settle quickly in the acid and the liquid is siphoned into a filter with strong vacuum, the chlorides / insolubles are the last to hit the filter as they have settled to the bottom. They are soft white fluffy chlorides and rinse easily with cold water.

Later they are removed from the filter and washed / soaked in hot water to remove any lead chloride. Overall they do not slow down the procedure other than requiring filtration to remove them. But that's normal with aqua regia as well if there is no nitric pre-treat of an inquart.

 

[HAuCl4]

So, for the record:

How long does it take to get all the bars/fine shot of 9999 fine gold from the moment you put the 3,000 Oz of scrap in the induction furnace?.

Melt- 5 minutes?
Gold mud atomized - 5 minutes?
Mud settled - 15 minutes.
Digestion in hot HCL-NaClO3 - 20 minutes ?.
AgCl filtering and washing - 20 minutes ?.
NH4Cl drop of Pt, Pd salts and filtering- 15 minutes ?
Gold drop and wash- 35 minutes?
Melt and pour of fine gold- 15 minutes ?.

 

[4metals]

Melt- 5 minutes?
Gold mud atomized - 5 minutes?
Mud settled - 15 minutes.
Digestion in hot HCL-NaClO3 - 20 minutes ?.
AgCl filtering and washing - 20 minutes ?.
NH4Cl drop of Pt, Pd salts and filtering- 15 minutes ?
Gold drop and wash- 35 minutes?
Melt and pour of fine gold- 15 minutes ?.

melt time to get from bars to molten 5 - 10 minutes
atomizing 2 t.o/second
settling, majority 15 minutes, balance 24 hours
digestion 30 minutes
filtering chlorides (about 85 gallons acid) 30 - 45 minutes
PGM Drop 5 minutes*
filtering again same as before
gold gassing 45 minutes
filtering again
washing gold 15 minutes
melt and pour 400 oz bars 30 minutes


total time around 6 hours


* if Pt , Pd is low in concentration it takes longer to re-settle and filter than its worth, most want to ship their gold and be paid for it within 24 hours so cementation and collecting when it accumulates is a better use of time.

 

[HAuCl4]

8) :shock: 8)

 

[goldenchild]

Was your solution warm whn you added the SMB to it. Cooling it down seems to help. Not as much gas goes poof up in mid air. Who is to say you are not loosing gold in those bubbles? 8)

I've only chilled my solution once and it didnt seem to make much of a difference to be honest. I think it may have the one time I dropped 7+ ounces (container got hot and foamed vigorously) but I usally only deal in 2 ounces or less. As far as the bubbles... I only recenly started using SMB dry. I used to dissolve it in water and then add to solution. It had much less of a reaction this way. Either way I choose to do it however, I always use a container with a lid. I dont close it but just rest it on the opening. This way the effervescence just accumulates on the lid/stopper and falls back into solution. Thats the beauty of the maxwell house container. The lid is plastic so I dont have to worry about contamination. Maybe I will record my next drop.

 

[4metals]

Oz wrote;

I put my gold chloride solutions in the freezer to precipitate my silver chloride, as the double dilution with water creates so much unnecessary waste.

In the late 80's I worked on a flow through refining machine in Ecuador that processed the placer ore from the local streams and rivers. The gold was digested in warm HCl and chlorine gas was bubbled through to dissolve the gold. To make it a continuous flow system we couldn't dilute the flow to remove chlorides so we used a cold trap to separate the liquid (gold chloride) from the insoluble silver chloride. The acid flowed into a 22 liter sealed flask with a drain on the bottom which could be opened to draw off accumulated chlorides while the acid proceeded to flow back into the system to be heated for oxalic precipitation. The flow was slow enough that silver settled in the large flask and the cold acid flowed on not needing any further filtration.

The machine had its share of problems due mostly to the size of the feedstock, we didn't have access to an atomizer then, but the freezing out of the chlorides worked perfectly.

 

[HAuCl4]

Oz wrote;

I put my gold chloride solutions in the freezer to precipitate my silver chloride, as the double dilution with water creates so much unnecessary waste.

In the late 80's I worked on a flow through refining machine in Ecuador that processed the placer ore from the local streams and rivers. The gold was digested in warm HCl and chlorine gas was bubbled through to dissolve the gold. To make it a continuous flow system we couldn't dilute the flow to remove chlorides so we used a cold trap to separate the liquid (gold chloride) from the insoluble silver chloride. The acid flowed into a 22 liter sealed flask with a drain on the bottom which could be opened to draw off accumulated chlorides while the acid proceeded to flow back into the system to be heated for oxalic precipitation. The flow was slow enough that silver settled in the large flask and the cold acid flowed on not needing any further filtration.

The machine had its share of problems due mostly to the size of the feedstock, we didn't have access to an atomizer then, but the freezing out of the chlorides worked perfectly.

How did they do the accounting?.

 

[4metals]

When we fed a weeks worth of alloy, we what knew came out and the gold solution in the lines and trap were drained and precipitated classically and all of the totals were added up.

During the cycle you only knew how much fine gold was coming out but the volume of the cold trap was a constant so the metal hung up in the volume could be estimated but it required draining to quantify it.

 

[HAuCl4]

Interesting. What were the advantages of making the process continuous instead of batch?. Man... you've been around!. 8)

 

[4metals]

I didn't design the device, I was hired because it wouldn't work continuously as a flow through continuous system. The best we could get it to do was for about 3 days production of 10 to 15 kilos a day before we had problems. The reason the owner wanted a continuous system was he felt he could set the thing in motion and fill the reservoirs and not have anyone with their fingers in his gold.

After about 4 weeks of processing and tweaking I suggested he break the system into pieces and process batches. When I left him that is what he was doing, I don't know if he ever found someone he could trust. Actually having known him, I wonder if there was ever a person created whom he could trust.

The one thing that remained in the circuit was the cold trap to eliminate the filtration by settling out the insoluble lead and silver chlorides.