Recommended setup to process 350oz of scrap jewery per week

[4metals]

There are 2 sides to every argument, until I became active on this forum I never imagined how hard it can be to get nitric acid in some locations. I've always ordered it in multiple 55 gallon drums. Then I come here and read how guys are making their own because they can't get it.
That was a surprise to me.

So to be fair to both sides, and to help our refining friend in Costa Rica make a better decision, inquarting with copper uses up a lot more nitric so if that is an issue in his neck of the woods then silver inquarting makes sense. If it is plentiful then copper makes sense. (With the understanding that life will get easier and chemical costs will go down when he accumulates enough silver to inquart with his own silver.)

If a few members who process gold filled scrap would speak up here we would hear that their feedstock is pre diluted with copper and zinc and they have no choice but to use nitric.

But the current price of gold seems to heal all wounds.

 

[Oz]

I was typing this (slow as I am) and noticed that 4metals has replied similarly. My reply is enough different that I still thought it worthwhile to post. I apologize for my slow typing skills.

OK, this thread has become about being right and petty arguments. There is seldom only one “right” answer.

Right. Or start with scrap copper or zinc or brass as the added metal for inquartation till he accumulates enough silver from the karat scrap. Silver is currently too expensive (IMO) to be buying it just for inquartation purposes.

Perhaps I read this wrong but HAuCl4 was suggesting only to start with base metals other than silver until the required silver was accumulated through processing, not as a permanent solution.

I've seen low karat without high silver. If the karat was lowered with CuZn alloy inquarting may not be required. As is so important in running batch lots in this business, you have to know what you are starting with, for that reason a small fire assay capability will pay off.

Now if 4metals is correct here little if any added metal may be required for inquartation.

I would stay away from zinc or zinc alloys in inquarting for toxicity reasons. Copper is a heavy consumer of nitric (3.4 times greater than silver) so I prefer silver for inquartation. However I can see circumstances where the cost of buying silver for inquartation is greater than the cost of consuming excess nitric by using copper. As soon as you have accumulated enough silver from processing, of course it would be expedient to switch to using the silver instead.

Having said that, if 4metals speculation is correct that this may be a low silver karat gold alloyed with Cu and or Zn, you cannot avoid the need to remove them. I would do my best not to add to that problem though.

Just one man's opinion.

 

[Oz]

If a few members who process gold filled scrap would speak up here we would hear that their feedstock is pre diluted with copper and zinc and they have no choice but to use nitric.

If accountability on lots was not an issue, then using gold fill scrap for inquartation is ideal! You get twice the work done for the same nitric consumption.

 

[goldenchild]

Couldn't xenfasa simply start out by melting all the gold, shotting it and then going straight to AR? This was suggested to me by a reputable member. With all the lower karats in the mix this will be plenty of copper to offset the silver. You WILL get some undigested corn flakes but... you can then either A. take the silver chloride produced, reduce it back to metallic silver and then use that to inquart the undigested material obviously digesting with nitric again or B. use the recovered gold to inquart the undigested material to make it a high karat for AR digestion. Either way you would use minimal nitric and build up the silver hoard everyone is fighting about.

 

[HAuCl4]

It requires a lot more skill and care in processing, but what you say goldenchild is doable. I prefer the speed and simplicity of inquarting and fluxing, and I'm sticking with that judgment unless extreme fineness is a requisite. The amount of acids and volumes used is similar though for the OP's material.

 

[xenfasa]

I think I am getting closer to a direction based on reading your comments.. plus have more details that may help.

I have a single seller with sufficient scrap 300-350oz
I have a single buyer wanting to buy 150oz per week

So the plans was/is to batch once a week and save a ton of labor.

I understand that inquarting is an easier process using less corrosive acids? Is that correct?
Are there other good reasons I should go that direction rather than AR?

I know buying extra silver is not in the budget but I also did not mention that I have at least 2 100oz bars I bought for about $600 each several years back for investment purposes.... Maybe it is time to dig them up and put them to use.

I have other junk silver and possibly other bars.. .but not sure how much I actually would want to melt.

Simple, efficient, less, labor, less chemicals and less equipment is better.. if it means me having to melt more of my silver. I can live with that.

So here is a math question for you inquarting gurus out there.
How much silver would I need to inquart 350oz of 10k scrap. Average maybe closer to 12k but I think 10k is a worse case scenario.

Next question... what would you guess is the average amount of silver in 100oz of 10k scrap... Just wondering since collecting the silver would be a nice bonus income at this production level. Could I expect 5% or 8% or more of 10k scrap to be silver?
That would mean maybe around 17oz-25oz of silver per batch per week I get to keep.

I was not thinking inquarting as a serious option before because of having to melt hundreds if not thousands of ounces of metal...
I guess with the right furnace it should not be too much of an issue?
What kinda furnace would I need for such? Preferably gas. Is propane an option for such furnaces?

I agree with other posts here about doing my own assays. Any real serious biz person I feel would do such.
I was looking at this assay kit here.... Beginners Assay Kit for $1500.
http://www.actionmining.com/bak.html
Is this enough to get me started? I think and hope it would be. Once the profits start rolling in, I can afford to invest in something better if necessary.
I will have 3rd parties verify my assays as well... if seller or buyer want. The main purpose would be to protect myself from getting ripped off by either side....... knowing what I have.. having assayed it myself.

thinking... of the assay process... I would melt a batch down. Do an assay to assess gold content of the batch before inquarting.
Then inquart, ... purify a gold sample and assay the purified gold. In a perfect world the gold contents before and after would jive... doing calculations from the first melt... to arrive at what the pure sample should be and actually is.

I am getting more excited as your feedback is helping me a lot....
any more comments with this new info I have provided?

Thanks again,
Xen

 

[4metals]

Action mining starter assay kit is for assaying ore, what you need is simpler. You will need a furnace, they sell Vncella Kilns, I've used them and they are excellent. You will need a good analytical balance, this will cost the most unless your association with university chemists can find you a balance to use. Today the balances are digital but the old analog balances were accurate and most universities had them and possibly they can be had cheap.

A good thread to read to set up a lab is on this forum. http://goldrefiningforum.com/phpBB3/viewtopic.php?f=41&t=4789

A gas melter can be made or had for a reasonable price, Action Mining has one which uses propane. There are inquartation calculators on the forum if you use the search function. Basically inquartation (the word) means to make in quarters. You want the gold to be 25% of the metal in the melt, or close. So you would add silver so the gold is 25%, in 12 karat gold the metals other than gold are another 25% so you will only have to add 50% in fine silver (or sterling if you have it)

Inquartation uses nitric acid. It is an easier process to clean up the gold but it will not produce .9995 gold by itself. It will provide a clean feedstock which aqua regia can easily clean up to make .9995 gold. It is a pre treatment which when followed by aqua regia equates to refining the gold twice. If you assay your gold and it is under 8% silver you can get similar results using one step as aqua regia. The silver and up to 1% by assay of the silver bar will be retained gold which is easily recovered in a small silver cell.

You are correct, batching into 1 process lot a week will save a lot of labor and only settling on 1 assay is even easier. You should run multiple cups and run a proof assay as well.

Read up on the previous forum threads and you will have a better idea of what you need to do. Then come back and ask more questions.

 

[xenfasa]

I just watched the mentioned videos and came back to the thread and it says to watch the videos...

A premature question if you do not mind me asking and to clarify.
For the inquarting process... only the silver is dissolved in the Nitric Acid, correct?
Other base metals including the gold are still left after the silver solution is filtered out.

How do you then refine the residue metal and gold grains/powder to gold? You still need to use the regular Aqua Regia process?
Or is there another recommended way to do things?

 

[4metals]

When you inquart with silver, all of the base metals and the silver and any palladium and some platinum will dissolve in the nitric solution. What remains will be 99% pure gold with some entrapped silver and some platinum if any was present. Additional treatment in nitric acid will clean it up a bit and it is possible using some fluxing techniques to get the purity to approach .999.

This is why you were asked what purity the gold you will sell has to be. If the gold is to be re-cast into jewelry it can be alloyed as it is providing the platinum is low or non existent.

It would be my guess that your client will want a minimum of .9995 fine gold. In that case, the sponge dissolves easily in aqua regia (and quickly) and the aqua regia refine step will upgrade the gold to what you need.

I suggest you inquart some gold, dissolve it in half nitric acid and half distilled water, and filter and wash the solids (gold) then you can melt this metal and just add a few granules of potassium nitrate which will flux off some, if not all, of the impurities. When you see the purity you have attained by inquarting, you can show it to your buyer and see if it passes muster.

It is not easy to assay pure gold. It is assayed by difference meaning the parts per million of all of the impurities are analyzed by instrumentation and subtracted from 100%. Generally if the gold bar has the pipe on the surface exposing beautiful gold crystals in the bar, it is purchased as pure. Try it, you may save yourself an entire step. This is easier to do with 10 to 20 ounces of gold rather than 1 ounce.

 

[xenfasa]

more details.
The buyer is wanting the gold to make jewelry for his well establish jewelry business.

I am not sure of the purity he wants/needs yet but hope to have that answer soon.

If he can settle for what I am left with after one run of inquarting and no AR than that would be great

I also have questions into a local environmental attorney with experience in such that will make sure we comply with the laws on using such chemicals I will update when I have that info as well. (want the green frogs to stay green)

Once I have a basic list of major supplies I THINK I will need. I will post back to this list as well as where I think I might be getting them.

I will also be checking with my chemistry professor friends at the largest University here in Costa Rica to see what equipment they can either provide or let me rent/borrow/use or break They will be involved in the project as well.

I think we have a great opportunity here.. with the scrap sellers sending to the US and the buyers importing from the US....
We save all that extra shipping and insurance and just process it all local.

I hope to start buying up some things in January and to have most all by the end of February. I may get quiet for a while here with the holidays coming up and traveling but I will be working on this and reading lots as I continue to create the perfect starter setup for this project.

Thanks again,
Xen

 

[EDI Refining]

Xen
reading your post, I highly suggest you start walking prior to running (refining 350oz per week)
Do what 4metals suggested in the post right above mine.


My question for you is. What accountability must you be at to be able to purchase the 350oz of scrap ?
What is your fine gold outlet, willing to pay you over spot for your finished product?

 

[4metals]

One thing you can definitely do is take one pass inquarted gold and alloy it up to return 14k and 10k alloys. Alloys sell for a premium and are easy to make, here in the states you can buy casting grain sized alloy which contains all of the required metals except the gold, in the proper proportions to make alloy. Just weigh out the alloy, add your gold, and melt it into bars. Assay to assure quality, and roll into flat stock, wire or whatever your buyer can use.

The cost of the rolling mills will be offset by steps and associated costs saved in the refining process. An in house assay lab can assure its quality.

Another benefit of only having to inquart and digest in nitric is you can make an effective fume scrubber which operates in an oxygen atmosphere and converts the nitric fumes which pass off as red fume into nitric acid which you can reuse.

This process cuts down on NO_x and recycles your chemistry. (Gold chloride will be very happy!)

 

[4metals]

If your buyer uses the gold in jewelry manufacture he also has other types of precious metal containing scrap such as polishing sweeps, bench filings, sprues from casting and possibly bombing liquid. If he uses 150 ounces of fine a week, the quantity of these wastes generated will be considerable.

These materials are also valuable and your buyer will need to have them refined as well. Considering the material you will be getting is the cream of the scrap, other refiners who may be doing the other wastes may offer better rates to get what you have plans to process. Considering you are starting out with one source, it would be wise for you to plan on processing these other materials as well. Just to keep the competition down.

Fortunately for you, all of these scrap-types have been discussed and are documented on this forum as well.

 

[xenfasa]

Xen
reading your post, I highly suggest you start walking prior to running (refining 350oz per week)
Do what 4metals suggested in the post right above mine.

Right but the 150oz/week buyer says all or nothing and wants a contract.
I am looking for ways to walk and will test things on a smaller scale to make sure we have no hiccups.

My question for you is. What accountability must you be at to be able to purchase the 350oz of scrap ?
What is your fine gold outlet, willing to pay you over spot for your finished product?

Buyer is paying just a small bit over spot with shipping and insurance. They do not NEED us but would be willing to do business locally with us if we can provide what they need for a similar price. They would buy at spot from us and be buying local.
We have verbal agreements with seller and buyer now but am working on getting at Letter of Intent from both.
All parties involved have great banking relationships including our side so we are exploring letters of credit or credit line with a mutual bank.
Worse case we do know others that can come up with hard cash to jump start things if we needed to do such.
In my perfect world the bank would give us a temporary credit line that would appease the seller and things will be settled when the buyer gets delivery. Only need $150,000 to float for a couple days or a week most. The first deal is the hardest until all parties are comfortable with it.
If we could pickup scrap in the morning refine in a day and deliver the next morning. There might not be a need to float anything if there is enough trust involved.

I also wonder if we could work it out so the buyer actually pays the seller for the gold then pays us the refining cut upon delivery...

But then the problem is security. Who ever possesses the gold is the one that should be taking the risk ideally and should have put up the cash sense gold is near cash. If stolen it can not be replaced.

All things we have been thinking about and trying to work out. Refining is only a part of the whole deal and big deals do not come without a lot of negotiating and planning.

I am hoping to get a lot of these details worked out on the biz side before I do any major purchasing on refining equipment.

Xen

 

[goldsilverpro]

The basic assay kit that Action Mining sells for $1500 lacks one very important thing - an analytical balance. Instead, they give you a comparator, which is a loupe magnifier or small microscope with a measuring scale built into it. In other words, you measure the diameter of the bead, instead of actually weighing it, and then use a funky chart to estimate the weight. Also, you have to estimate the ratio of silver/gold in the bead by color. Terrible system. To me, this is a monetary disaster waiting to happen, especially when dealing with something valuable like karat gold. You would probably be more accurate by going by the markings on the jewelry and eliminating the assay. A .0001g analytical balance would cost an additional $1500, more or less. It's a necessity.

 

[nickvc]

Xen
I think you might have an easier route to financing the deal than you think.
If your seller is sending his scrap to the US for sale then he will have to wait until it arrives before getting payment or even part payment until it's melted and assayed. That should give you 24 - 48 hours of a window to refine his metals and sell to your end user. The same no doubt applies to your buyer no metal until the funds are sent.
If as you say both parties know each other and you can act as the intermediary basically brokering the transaction you can also get them to agree a date of fixing the price so you don't take a risk on the price movements which can quickly erode your margins.
If you set this up properly you should be able to process the gold within the window but bear in mind that you will not get all the gold out that you expect so allow 1% of the metal to be in the system, this is recoverable, it's not lost, but will need concentrating to be economical to recover.

 

[HAuCl4]

4metals: Do you actually use oxygen or compressed air for the NO_x scrubber?. Can you further describe your system?. Mine was a simple series of water tanks where the NO_x and air was bubbled in the first tank and then the bubbles passed through the remaining connected in series tanks. It wasn't 100% efficient, but adequate for those small operations.

IMHO: After rereading this thread and the OP's intended operation and further information he has provided, I now think that the OP has a potential disaster on wheels in his hands, and that he'll do well taking things very slowly and carefully. Remember that you can lose a lot more than the gold or money in this business, especially in Central America. The technical part is the easy part.

The OP has not stated yet on what specific terms/prices he intends to purchase the gold or sell it, so really we do not even know if he has a potential viable operation or a dream in the clouds. At this point I would bet his seller wants to sell at premium over spot and get paid in advance and his buyer wants to buy at discount and pay a week later...sigh. You haven't said either if the buyer is willing to buy at all times and the seller want to sell everyday. Sometimes when prices move one of your sides will not want to fix the price, etc, etc, etc x etc one hundred times more etc. Ideally you want to put yourself in the position of not taking price risk/any risk and just collect your margin. How do you plan to achieve that?.

p.s.: Do you see that pic below my moniker showing several bars of gold?. That is a stash that the Colombian authorities seized from a truck driver that was covering a route between Colombia and Venezuela. Nobody has laid claim to the gold yet. Who knows where the gold is at this very moment. It happened a few weeks ago. Do you think the owner is really thinking about how much nitric acid he's going to use in his next batch?.:lol:

 

[4metals]

gold chloride,

If dissolving silver in nitric, no chlorides, the fume will be NO_x which will convert to HNO₃ if the reaction is carried out in an oxygen environment. The nitric acid builds up in concentration to about 50% acid which can be reused. The nitric strength is measured via hydrometer.

When the acid is drawn off it is replaced with distilled water. The system is purged with oxygen before the reaction is kicked off and the bubbles in the glass cylinder give an indication of flow rate.

Obviously the entire system has to be air tight.

This system was called the Johnson system and more details can be had from Butts & Coxe.

And you thought I didn't recycle anything! :lol:

 

[xenfasa]

Last time we checked with seller, it seemed we would be able to get the gold content at 90% of the value. I have a meeting today and will know more soon

The other thing I/we need to keep in mind is we know old time miners in the countryside that just dig for nuggets. The idea also is to provide them equipment to make their life more easy in return for selling us their gold. They are selling cheap now. So any refining operation for jewelry I hope, could help us process ore to some degree in the future but I realize some of the processing and equipment will be different.

 

[4metals]

The moderators would like to thank all of the members that contributed to the original thread upon which this thread was based, as well as those that asked questions showing what was missing. Because of the extra length and interest in this thread we have created the above consolidated version making for an easier read. We encourage all members to read, comment, and ask questions in the original thread, Recommended setup to process 350 oz of scrap jewelry per week

The Library threads should not be considered to constitute a complete education. Instead, they're more like reading a single book on the subject of recovery and refining. There is so much more information on the forum, and it is impossible to include it all in these condensed threads. Members are strongly encouraged to read the rest of the forum to round out their education.

For those who prefer a printed copy, a pdf file of this thread is provided below.