Cyanide/Cyanate leaching using Brackish Water?

[Punterr]

Hi Punterr,

You're right.

I'm sorry, I didn't mean to blame you.

In my fantasy, I saw a remote little bay with a little cabin. Fresh water is rare (maybe collected rain water) and the next sewerage is miles away.

In reality, mabe your shop is located in a harbor city with a harbor basin right in front of and you just want to safe fresh water.

Sorry, peace brother!
With best regards.

No Problem Brother, you are half right, we are in the bay, 30m from the beach (with the coconut palms), with our cabins/buildings, however, we do have fresh water from a deep well maybe 160 feet down, not much sewage here, water is relatively clean.

This is essentially a very small, one man (ish) operation, values are tested at around +50g Au/ton, but proving very difficult to get the values out..

Any solid waste is neutralised and converted to concrete blocks for building, liquid waste is filtered and water reused.

We dont need much production, maybe 1m3 per week (around 60g Au), that is enough for me.. not to be greedy..

 

[BlackLabel]

If I think about a beach with palms, I see bright sand from ground sea shells…
I wouldn't expect gold bearing ore that close to the shore. Or do you work river gravel?

I guess you are from south east Asia, Indonesia? I'm from Germany, never been in Asia so I'm curious.

 

[Punterr]

If I think about a beach with palms, I see bright sand from ground sea shells…
I wouldn't expect gold bearing ore that close to the shore. Or do you work river gravel?

I guess you are from south east Asia, Indonesia? I'm from Germany, never been in Asia so I'm curious.

Our place is between 2 estuaries which are fed from an old volcano around 8-12km away. Gery/Black volcanic sand. When it rains 'stuff' is washed down the tributaries into our area and accumulates on the beach. I am British, and now located in Philippines.

 

[BlackLabel]

Many thanks for these information.
This material sounds interesting.
Gold particles just visible?

I've to quit now, have to get up in four hours… bye.

 

[Punterr]

Some of the particles look like gold flakes, however they are not directly, but are made of thousands of particles of gold (and other Precious Metals in different flakes), smaller than #2000 mesh and encapsulated in some sort of a resin, which is impervious to most things except heat of around 1200C or more.

 

[BlackLabel]

Wow - so much mega-micro nuggets! ;-)

Two days ago, I panned out some material from a gravel pit. I have it laying around for years. The gold was about the size like you show with the ruler.

 

[Deano]

In commercial applications cyanide works perfectly well in brackish water.
The greatest problem caused by brackish water is the buffering action of the water which means that it often becomes extremely difficult, and expensive, to raise the solution pH into a safe working range for cyanide.
Some operators modified their leach tanks to run at pH 7 with recirculating extractor fans and caustic adsorption sections for the HCN.
Expensive to do but cheaper than shovelling in huge amounts of alkali, not recommended for small operations.
Deano

 

[Ultrax]

In commercial applications cyanide works perfectly well in brackish water.
The greatest problem caused by brackish water is the buffering action of the water which means that it often becomes extremely difficult, and expensive, to raise the solution pH into a safe working range for cyanide.
Some operators modified their leach tanks to run at pH 7 with recirculating extractor fans and caustic adsorption sections for the HCN.
Expensive to do but cheaper than shovelling in huge amounts of alkali, not recommended for small operations.
Deano

Yes, but with sodium salts in small amounts (due to buffering of the solution, yes). But the author of the topic asked about seawater. Magnesium chloride should be removed from the water, for the reasons that I indicated above. I certainly wouldn't agree to work with cyanide near neutral pH, even with an ultra-reliable extractor of possible amounts of free HCN, for any money. Accidents are always possible due to inattentiveness or negligence (human factor). Working in such conditions is a very significant risk to life and health.
Even if the owner of the enterprise convinces their employees of 100% compliance with safety requirements For small businesses, cyanidation is generally unprofitable and dangerous

 

[Punterr]

In commercial applications cyanide works perfectly well in brackish water.
The greatest problem caused by brackish water is the buffering action of the water which means that it often becomes extremely difficult, and expensive, to raise the solution pH into a safe working range for cyanide.
Some operators modified their leach tanks to run at pH 7 with recirculating extractor fans and caustic adsorption sections for the HCN.
Expensive to do but cheaper than shovelling in huge amounts of alkali, not recommended for small operations.
Deano

Hi Deano, thanks for the input. Is it safe to assume the same applies to Cyanate (OCN) type leach solutions (JinChan, etc), or is it different somehow?

 

[Punterr]

Yes, but with sodium salts in small amounts (due to buffering of the solution, yes). But the author of the topic asked about seawater. Magnesium chloride should be removed from the water, for the reasons that I indicated above. I certainly wouldn't agree to work with cyanide near neutral pH, even with an ultra-reliable extractor of possible amounts of free HCN, for any money. Accidents are always possible due to inattentiveness or negligence (human factor). Working in such conditions is a very significant risk to life and health.
Even if the owner of the enterprise convinces their employees of 100% compliance with safety requirements For small businesses, cyanidation is generally unprofitable and dangerous

Hi Ultrax,
There are no employees, only myself , very small operation, maybe 1m3 production per week is all that is intended, this "should" give me around 2 ozt if all goes well. Our available leaching solutions are:
1. Cyanide (NaCN),
2. JinChan (Eco-Goldex)
3. Or Hypo type leaching (NaCl+Ca(OCL)2 )

Any advice will be graciously recieved

 

[Ultrax]

Judging by the photo, you have fine flakes of gold - usually, it contains quite a lot of silver. Have you checked the quantitative % composition for silver? The applicability of different types of technologies may depend on this. Also, have you tried gravitational methods, perhaps concentrating table is the best solution for your volume near 1m3 per week?

 

[Punterr]

Judging by the photo, you have fine flakes of gold - usually, it contains quite a lot of silver. Have you checked the quantitative % composition for silver? The applicability of different types of technologies may depend on this. Also, have you tried gravitational methods, perhaps concentrating table is the best solution for your volume near 1m3 per week?

Yes, there is quite a lot of silver. been down this road since 2016... it is not gold directly and it is not possible to separate with gravity (unfortunately). What it is has confused the labs in UK and USA/Canada.

After much confusion, what we have here is gold micro/nano particles (and silver) embedded in some sort of (best described as) encapsulating 'resin'. The particles are smaller than 2000mesh. The resin melts at around 1250C, the resin is impervious to strong alkaline and acid. Fire assay shows (conservatively) 50g Au and 2500g Ag per ton of ore, I have personally achieved 42g Au per ton in testing but the testing is inconsistent to say the least. I have never managed to recover any silver except one time using Hypo leaching under pressure.. the ore is very annoying stuff to say the least.. what is also hampering things is access to a suitable lab here in Philippines. Before i used to send the samples around the world but that is not possible now.

 

[Deano]

When I said brackish water I meant water with dissolved salts to a level greater than sea water, there used to be a lot of operations in Australia using these types of water.
If a source of purer water was also available then shandying the two types often gave a product which, while not as good as commercial water, was a vast improvement on the brackish water on its own.
Straight cyanide, ferro/ferri cyanides, ecogoldex are all cyanide leaches and require pH above 11 for safe operation.
Only the straight cyanide and ferro/ferri cyanides are capable of loading the gold onto carbon and have that carbon stripped with high gold recovery levels.
The neutral pH chlorine leach will load and strip using carbon, the downside is that all wetted surfaces must be resistant to the leach solution.
Thiocyanate leaching using ferric chloride at pH 2 will also load and strip well, the downside is as above.
All other leaching agents are too expensive for commercial usage.
Deano

 

[Punterr]

I do have fresh water which I can mix with the sea water maybe 1:1. The leaching is done in non metalic vessels, all pipework is PE. I am seeing dissolved iron in the leach for some reason (maybe from magnetite?), if i use Hydrazine Sulphate as an indicator the initial PH will be around 2 (pale green in the spoon test), if i then increase the PH with NaOH, the precipitate changes to light brown. My starting ph is general around 11 and leaching cycle is around 24hrs, if left unaltered, the ph drops to between 8.5 and 9.5 depending on the temp.