Waste treatment system at Gold Refinery

[Gold.refinery]

I took a few pieces of blue hydroxide, crushed them and mixed them.
I tested with XRF, in some places it averaged 17/1000 to 28/1000 gold, and it also had about 4/1000 platinum.

I know the standard for testing powders varies, but some color changes were visible on the XRF lens, which also varied in Numerical values.

These values may have passed to the last station due to the presence of ammonia in the solution.???

 

[silver1]

I took a few pieces of blue hydroxide, crushed them and mixed them.
I tested with XRF, in some places it averaged 17/1000 to 28/1000 gold, and it also had about 4/1000 platinum.

I know the standard for testing powders varies, but some color changes were visible on the XRF lens, which also varied in Numerical values.

These values may have passed to the last station due to the presence of ammonia in the solution.???

Could be a whole lot of reasons. No answer for that right now as your still trying to work out the kinks in your process and system. Once 4metals and these guys gets you hooked up this problem will solve itself. It's like death from a thousand cuts when your chasing the answer to a problem. It's a combination of problems and not just a specific one. Maybe someone can help you with the hydroxide issue you are facing now though.

 

[Gold.refinery]

It's like death from a thousand cuts when your chasing the answer to a problem.

Exactly …

 

[4metals]

What is the volume of the tank you will be cementing the waste solutions in? And do you expect to refine 1 lot of 20-25kg per day? This will help work out your wastes retention time in the tank. The speed may not be an issue. And you need to get it out of your head that you are going to recover a few grams of gold from your cemented waste on a lot by lot basis. After the cemented waste sits in the tank agitated and exposed to copper metal the values will drop. You will empty the tank to the next treatment step and preferably pump through a canister filter to catch any values before the waste tank. You empty the tank, leaving what has settled on the bottom and refill the tank with fresh spent solution for cementation. The tank is emptied and cleaned out on a schedule that likely approaches once a month. You cannot afford the labor or the chemistry to chase after small amounts from each lot.

 

[Gold.refinery]

What is the volume of the tank you will be cementing the waste solutions in?

4 cubic Tank= 4*500 liter

2 cylindrical Tank = 2*300 liter
(Except for the gold settling tank)

And do you expect to refine 1 lot of 20-25kg per day?

Maybe 15 kg daily

And you need to get it out of your head that you are going to recover a few grams of gold from your cemented waste on a lot by lot basis

Why?
Can not workshop that recycle by non-chemical methods recover low values(Smelting)?

After the cemented waste sits in the tank agitated and exposed to copper metal the values will drop. You will empty the tank to the next treatment step and preferably pump through a canister filter to catch any values before the waste tank. You empty the tank, leaving what has settled on the bottom and refill the tank with fresh spent solution for cementation. The tank is emptied and cleaned out on a schedule that likely approaches once a month. You cannot afford the labor or the chemistry to chase after small amounts from each lot.

Can you explain a little more and more clearly. I'm confused

 

[Yggdrasil]

4 cubic Tank= 4*500 liter

2 cylindrical Tank = 2*300 liter
(Except for the gold settling tank)


Maybe 15 kg daily

4metals said:

And you need to get it out of your head that you are going to recover a few grams of gold from your cemented waste on a lot by lot basis

Why?
Can not workshop that recycle by non-chemical methods recover low values(Smelting)?
Because it is not practical to cement then settle and so clean out the tank after each lot.
It is labor intensive and takes time.
Better cement and let settle, filter out what is there and the tank is ready for a new batch.

4metals said:
After the cemented waste sits in the tank agitated and exposed to copper metal the values will drop. You will empty the tank to the next treatment step and preferably pump through a canister filter to catch any values before the waste tank. You empty the tank, leaving what has settled on the bottom and refill the tank with fresh spent solution for cementation. The tank is emptied and cleaned out on a schedule that likely approaches once a month. You cannot afford the labor or the chemistry to chase after small amounts from each lot.

Can you explain a little more and more clearly. I'm confused
Here 4metals explain why you should not do it lot by lot.

 

[Shark]

Chasing .25% has the potential to cost more than the values recovered. “Spending dollars to chase dimes” is a saying we use fairly often to describe those situations.

 

[Yggdrasil]

If you read the "Cementing it out" thread you will se a description on a device one of our members made, to increase the agitation around the copper.
It basically is a piece of plastic tube within which the copper are placed/hung.
Inside this, a piece of plastic hose to the bottom, bubbles air, this will create a strong turbulent flow around the copper and also circulate the whole tank.
For a large tank it may be better with more than one, or even have a smaller temporary tank on top of the main tank and a small pump circulating the liquid through copper scrap and then back into the main tank. There are many ways to do it.

 

[Gold.refinery]

Before the hydroxide tank, we have 4 tanks.

Two 300 liter tanks without mixer, one tank with mixer and blade, one tank with air injection for stirring. How to use these tanks to maximize copper cementation to obtain residual values?

 

[Yggdrasil]

Before the hydroxide tank, we have 4 tanks.

Two 300 liter tanks without mixer, one tank with mixer and blade, one tank with air injection for stirring. How to use these tanks to maximize copper cementation to obtain residual values?

Do you read the links and threads we give you?

 

[Yggdrasil]

Do you have a layout drawing/Sketch?

 

[4metals]

4 cubic Tank= 4*500 liter

2 cylindrical Tank = 2*300 liter
(Except for the gold settling tank)

You didn't mention the cylindrical tanks or the gold settling tank. Where in the line of tanks do these fit in. Is one of the cylindrical tanks where you precipitate the gold? What is the other one for? and which one is the gold settling tank. (if you filter it properly you have no need for a tank where it settles out) You cannot keep adding tanks and expect us to know what you are doing. You sent us photo's of 4 cubic tanks prominently numbered 1,2,3,4. now 2 or 3 more spring up?

Can you explain a little more and more clearly. I'm confused
Here 4metals explain why you should not do it lot by lot.

If you do it lot by lot we will see you post your equipment up for sale because you cannot make any money. Someone who knows how to do this will use your equipment (purchased at auction rather inexpensively) and produce good saleable gold and handle the wastes and values collected from the process hang-ups (that 0.25%) If you get your filters working properly and pump the solutions to the proper tanks for processing you will not need to do it lot by lot. And if you feel you must do it lot by lot, you are in the wrong business. Most of your gold will be in the chlorides anyway.

Assuming the first of the 4 tanks (the square ones) are 500 liters and you process 15kg a day. You will use about 65 liters of acid. Generally you will use about the same quantity of water rinsing everything down and cooling it. So daily you will generate 130 liters of waste. That gives you 500/130= 3.84 days before the tank is full. Earlier I suggested when the first tank is full start adding to the second (500 liter) tank. When tank 2 is half full check tank 1 with stannous for values. All the while tank 1 is mixing to keep the solution in motion and keep new solution contacting copper metal. If you detect any values on stannous, add fine powdered (atomized copper) do not add a lot and keep it mixing because if it settles to the bottom it is not as effective. The next morning the PM's should be out of solution and the solution can be pumped, after it settles, to waste treatment. Pump it through a canister filter to trap any values that are still suspended. The solution you are now pumping out will not hold payable quantities of precious metal and are, as the name implies, waste acid. This is what you drop with caustic to form hydroxides. If you use the 2 tanks alternatively, you will be able to hold solution for 3 or 4 days to allow the copper slabs to work and if needed some fine atomized copper metal can finish the job.

 

[Yggdrasil]

Just to visualize the cementing contraption, I made this sketch so it may be easier to understand.
At lest this is close to how I do it.
It has been made transparent to emphasize function.

 

[Gold.refinery]

You didn't mention the cylindrical tanks or the gold settling tank. Where in the line of tanks do these fit in. Is one of the cylindrical tanks where you precipitate the gold? What is the other one for? and which one is the gold settling tank. (if you filter it properly you have no need for a tank where it settles out) You cannot keep adding tanks and expect us to know what you are doing. You sent us photo's of 4 cubic tanks prominently numbered 1,2,3,4. now 2 or 3 more spring up?

You can see all the cylindrical tanks with filters and waste water stations in the two photos below.

Now you recommend the best route.
You will probably skip some tanks.
We can skip. Or use them for more time to Contact with copper.

 

[orvi]

Chasing .25% has the potential to cost more than the values recovered. “Spending dollars to chase dimes” is a saying we use fairly often to describe those situations.

28/1000 is 2.8 % if I calculated it correctly. If true, that is very concerning number. At least as I see it - obtaining solid hydroxide cake with more than 2% gold. Maybe the readout of the XRF isn´t correct.

 

[Yggdrasil]

I asked for a layout or if not possible for a sketch so we can make a plan for the flow.
Since the OP have not reacted I made one from the pictures.
But it is highly inaccurate since I don't know the shape/size of the room and so on.
So please give some input to this.


Edit: Swapped Sketch to one with text.

 

[orvi]

We can skip. Or use them for more time to Contact with copper.

Speed of cementation is proportional to active surface area of copper plate/bar. If the solution only sit in the tank, only mixing force is diffusion, and that is very very slow for you purposes. You need to move the solution. Either by mixing or with air bubbler. Not just a small stream of bubbles, you need it to bubble quite a lot - of course, not that violent it spits the solution everywhere

If any gold is present in soluble form as Au3+, it will fall off on the surface of the copper as brown precipitate. More contact time surely help to assure you, that all values were precipitated. But on the other hand, in acidic solution, and in presence of air, copper is dissolved even in HCL. So it is a balance act of necessity and certainty If you want to speed the cementation, use multiple pieces of copper sheet metal or casted flat bars to increase surface area. Don´t forget to brush the surface of the copper after cementation - some gold can be still attached to the surface of the copper, but gentle brushing will take it off. The quickest way how to dross off the gold powder from copper is to use ultrasonic cleaner. But considering the size of copper bars, it will probably be impractical.

As 4metals told you, stannous test will tell you if there is a soluble gold in solution.
If you want to be completely sure, you can take small portion of the solution (say 200 mL) and use aluminium or zinc to completely cement all of the metals to the sludge. Filter the sludge and measure with XRF. But I think that with stannous and trained eye, you will be fine.

 

[Gold.refinery]

I asked for a layout or if not possible for a sketch so we can make a plan for the flow.
Since the OP have not reacted I made one from the pictures.

 

[Yggdrasil]

Thanks, it is much easier to see the flow when you know how things are placed.

 

[4metals]

I'm a bit busy today but if you provide one more photo of the inside of the tank so we can see the drainage of the gold precipitation tank it will be helpful. From the image you just posted it appears the entire tank will not drain into the filter.

This evening I will list every step and where it is done and issues you may face.