DIY Cone Mold (w/pics and questions)

[Yukon99669]

So I was looking for a smallish cast iron cone mold to smelt several small batches of cons from different locations using GPK Premium Gold Flux.
I kind of needed it tomorrow, not in 2 weeks, so I cobbled together what I could with some scraps I had around here.
The only chunk of metal that had enough meat on it was an old hitch ball. I heard about people using angle iron for makeshift cone molds so I figured this should work at least as good….hopefully.
For The bulk of the cavity I used a step bit through the middle, I wallowed out the top w/ a 1/2” bit and bottomed it out with a 1/2” countersink bit.

I intend to heat it up to 500 or so and spray some graphite on it for release.

….so my questions:
-Is it going to work?
-should I smooth out the walls more?
-should I heat it cherry red before using it initially?
-would it be possible to use as a crucible and mold w/out having to pour?
-am I overlooking anything?

Here’s a cpl. Pics, and thanks for any advice!

 

[Martijn]

Welcome to the forum. New season starting? Love the yukon gold rush series!! Have you ever melted gold or any metal before?
Looking at the size of your mold, you could just leave the gold to solidify in the crucible and pick it out before the flux solidifies.

If you use a lot of flux, the mold will be too small for the pour.

So are you going to melt concentrated gold in a small crucible or smelt away base metals from cons with a lot of black sands in a big crucible? The latter requires a collector metal like lead or silver and a lot of flux which will not fit in that tiny mold. Some sulfur and an iron rod may help as well with the molten chemistry.

Clean gold does not need flux to melt. You can just pick that out of a crucible after melting. Just glaze it with borax first, if it's not a graphite crucible.

So pan it out better and melt in stead of smelting?

Jason from Mount baker mining machines has a good video on smelting black sands after the shaker table. Look on you tube for his channel.

Graphite will be blown away, soot the mold with a reducing flame. Like with a candle. Yellow flame.
Smoother mold means better release of the button.
Try it to find out.

 

[Yukon99669]

Thanks for the reply Martijn!

I have melted down some of my nearly pure gold using borax. I haven’t smelted before though.
What I am doing here is smelting quite a few really small batches of cons from several different spots on my claim. The samples are cons are all -100 and about 50/50 gold and non magnetic black sand….quite a bit of the BS is garnet.
I was under the impression that smelting with the GPK flux, that I wouldn’t need anything additional, as it tends to treat everything non-gold as a impurity’s.
Here is a link:
http://www.gpkcompany.com/GPK-Premium-Gold-Flux-black-1-lb_p_73.html

 

[Martijn]

Ok. I have read the description.

According to what's promised, you will loose some silver, but will end up with a pure gold button, that needs to be enough to collect all the tiny gold buttons floating in the flux.

What is the recommended ratio of cons/flux? How long does it need to stay molten at which temp? How pure do your cons need to be for proper smelting?

I'm missing a manual on how this product has to be used to work effective and info on how effective it can be under perfect conditions. It sounds great, but does it actually work?

Promises make for good sales, not for satisfied customers. If the manufacturer can not provide these details, do not buy the product.

Martijn.

 

[kurtak]

I was under the impression that smelting with the GPK flux,

Are you planning to do this with a torch - or in a furnace ?

I ask because in order for the flux to dissolve the black sand & slag it off it takes "time" once everything is molten for that to happen

Also - the black sand needs to be ground very fine for the above to really be effective (like 100 minus mess fine or "finer" - the finer the better)

So - although torch smelting can be done (on VERY small samples) it is at best VERY difficult

The samples are cons are all -100 and about 50/50 gold and non magnetic black sand

I assume you mean 100 grams of 50/50 gold/sand

To dissolve that much black sand with that flux will need at least 200 grams of flux

So that is 300 grams flux/black sand/gold - that is going to be VERY hard to do with a torch

You really need a furnace

Kurt

 

[kurtak]

Ok. I have read the description.

According to what's promised, you will loose some silver, but will end up with a pure gold button, that needs to be enough to collect all the tiny gold buttons floating in the flux.

What is the recommended ratio of cons/flux? How long does it need to stay molten at which temp? How pure do your cons need to be for proper smelting?

I'm missing a manual on how this product has to be used to work effective and info on how effective it can be under perfect conditions. It sounds great, but does it actually work?

Promises make for good sales, not for satisfied customers. If the manufacturer can not provide these details, do not buy the product.

Martijn.

What Martijn said

Kurt

 

[4metals]

As Kurt pointed out, the finer the grind the better the contact between the flux and the material. Note this flux will hold silver so be aware.
The only issue with a trailer hitch ball cone mold is it isn’t very big.
My suggestion is fine grind, mix with generous portions of the flux and have a reasonable soak time.
Most of the flux will overspill the cone so place a tray under it but all of the molten metal will pool and fall to the bottom of the cone.
Small cone molds are used used for fire assays but even those have more volume than your bumper hitch mold!

 

[Yukon99669]

Not 100 grams.
All the material is classified to -100, actually -70. I’ve panned out everything above that.

I’m only working this material in batches about the size of a teaspoon, by volume…I haven’t weighed it so not sure gram wise what it is.

I do have an electric furnace, as well as a cpl. Propane torches and forges if necessary.

 

[Yukon99669]

I just requested MSDS and instructions from the manufacturer. I’ll post what they send over.

…also ordered a bigger cast iron cone mold from Legend and grabbed a 3/4” countersink bit to open this one up a bit more.

I’ll post some pics and details as soon as I get this finished up.

 

[Yukon99669]

Ok, here is the 4 pages if “tips” that they sent over….I haven’t read the though it yet, but figured I’d throw it you way ASAP:

• these pages we’re going to pass on any tips or suggestions on how to make your smelting experience
  successful, easier and help keep it fun rather than frustrating.
  
  
  FLUX: Understanding how the GPK Premium Black Flux works can help everyone with their smelting experience. You cannot
  smelt readily without flux. The objective of the flux is to suspend and trap the impurities contained in the concentrates during
  the smelting process - thus allowing the precious metals to separate from them – whereby they can then be poured into your
  mold. We designed a non-lead based flux for home use due to the health and environmental concerns raised when using the
  conventional lead based fluxes. The lead based fluxes with litharge can be successfully used with any GPK Kiln, however,
  litharge is only necessary when doing a fire assay or fine gold.
  GPK Premium Black Flux is recommended for melting pure gold, or smelting gold ore concentrates. The black flux is
  designed to help remove impurities from gold, including copper, silver, etc. It will treat them as a base metal and oxidize them.
  Crucibles Note: Since the manganese dioxide in the black flux oxidizes base metals into silicate, it attacks graphite or clay
  graphite crucibles, which are neutral. Black flux works better with clay or fused silica crucibles.
  GPK White Flux is best for melting pure silver, copper, brass, etc., or smelting silver ore. OR: for gold ore with silver or copper
  that you wish to retain, however; you will end up with an amalgam, since our kilns cannot separate the different precious
  metals. Crucibles Note: White flux has no manganese dioxide, therefore; there is no conflict between the flux and a graphite
  crucible – if there is not much black sand in your concentrates. Clay or fused silica crucibles are susceptible to being eroded
  by the borax in both fluxes and last fewer pours than graphite or clay graphite crucibles. Clear as mud? Light crucibles for
  dark flux / dark crucibles for light flux!
  
  THE PROCESS: When your concentrate is thoroughly mixed with the flux and put into the crucible and set inside the kiln, the
  flux and precious metals melt and the impurities are taken up by the flux and suspended so that you can pour the smelted
  precious metals from the mixture after sufficient temperatures are reached inside of the crucible. Note: The flux must be
  absolutely dry, or it can cause boiling over in the crucible. If it gets moisture in it, try warming it to 300°F or 400°F in a pan on
  the stove – look for steam – until it is thoroughly dry and there is no steam.
  
  CONCENTRATES TO FLUX RATIOS: Generally, you want to use 3 to 4 parts flux for 1 part ore concentrates. However; this
  is a guideline only, for everyone to work with, not absolutes. The more pure the precious metal you are melting, or the ore
  concentrate you are smelting, the less flux is needed. An easy mistake to make is to start out with an excessive amount of
  black sand concentrate to flux. Now, if we overload the flux9s ability to suspend and take up the impurities contained within in
  the crucible by adding too much black sand concentrates or jewelry, we won9t get a good recovery of our precious metals.
  Rather, some of the precious metal will be bound up within the remaining sands or concentrates in the crucible. So as a
  remedy, add less of the concentrates or more flux to the crucible to get the correct ratios. If you start with small amounts of
  your concentrate and provide an excess amount of flux, the process is much easier to get a handle on. You can then ramp
  up the amount of concentrate to flux as your successful experiences allow and, within a few smelts, you will have arrived at a
  ratio that provides both good recovery and a small amount of excess flux in the smelt to deal with the impurities. The good
  thing about this smelting process is that you can always crush your flux after it9s cooled and do it over when things go bad.
  So here9s a simple rule of thumb; Start small and ramp up as your smelting experience grows. Once you get a handle on
  things, the 1 part concentrate to 3 or 4 parts flux is going to be pretty close and works well with concentrates. Again, remember:
  the fewer impurities contained in the concentrates to begin with, the more concentrates can be added to a given amount of
  flux and still get a good precious metal recovery.
  
  GRINDING BLACK SANDS: Often the very fine gold contained in black sand can be literally locked up inside the sand
  particles, called <micro-encapsulation=, or simply stuck to the sand particle itself. A user suggested this tip to use prior to
  roasting and it seems to work really well: Take a trip to the thrift store and pick up a used blender. Put your black sand into
  the blender and grind the heck out of it. This can help liberate the <micro-encapsulated= particles and free up the stuck gold
  particles so they can be smelted more readily. Use small amounts, so you don9t overload the blender with your black sand.
  You want it to flow around and contact the blender blades as much as possible. The finer your black sand is, the better it is
  for smelting. Another benefit of the <grinding= process is that it will help increase the homogenous mixture of your black sand
• 
  with the flux that is necessary prior to smelting it. If your mixture is not homogenous and there is an excess of black sand
  contacting your crucible during smelting, a phenomenon I call a <thermite type= reaction can take place and burn a hole in the
  side of your crucible. Not a good situation to say the least; the finer your black sand is the better. Caution: Do not use the
  kitchen blender - you will be found out.
  
  ROASTING YOUR CONCENTRATES: Here9s a suggestion from us and a couple of GPK users that can help with some
  types of concentrate and is absolutely necessary for sulfide and partially oxidized ore concentrates. Remember: the less junk
  in your crucible, the easier it is to smelt out your precious metals from the concentrates and the better your flux will work
  during the smelting process. You need a metal gold pan and a propane fired type stove burner to accomplish this roasting
  step: Put your metal gold pan on your propane burner and turn the burner up on high. Spread a thin layer of your black sand
  concentrates in the metal gold pan and heat it up. Stir it occasionally and keep roasting it until it stops smoking and smelling.
  Obviously, this needs to be accomplished outside in good ventilation and you need to stay the heck out of the way of the
  smoke and fumes coming off the roasting concentrates. Don9t worry; your gold is not going anywhere - unless the wind is
  blowing about 40 miles an hour - then everything is going away. Once the concentrates are roasted, let the gold pan cool off
  and put your roasted concentrates in a suitable container. When you have enough of the roasted concentrates, you can then
  smelt them as outlined in the instructions. These steps can really enhance the effectiveness of the smelting process. Even if
  you don9t <grind= your concentrates, the roasting step will definitely help your recovery.
  
  ROASTING SULFIDES: Roasting your sulfide and partially oxidized ores prior to smelting is pretty much the same as roasting
  black sands, with some exceptions. Obviously, your concentrates need to be concentrated. Panning your crushed ore, or
  using some other method of removing as much of the gangue material prior to smelting or roasting, is absolutely necessary.
  The next step is to take your propane burner and metal gold pan out somewhere where there are no neighbors or your wife
  to call the police or 911 on you, thinking you9re creating some kind of a bomb. Roasting a sulfide ore and driving the sulfur off
  to oxidize the ore smells really bad - ten times worse than the morning after any card playing, beer drinking, pickle egg eating
  party we used to attend (or still do). Spread them out in your metal gold pan, turn the burner on high and stir them occasionally
  until they reach 800°F to 1000°F and stop smoking and smelling like brimstone and hell itself. Again: stay the heck out of the
  fumes and smoke – very toxic. Roasting sulfide ore prior to smelting is absolutely necessary. Sulfides not thoroughly roasted
  will steam and spit and mess everything up when you go to smelt them; the driving off of the sulfur causes acidic reactions in
  the smelting process, raising heck with the crucible and the ph of the flux itself. Separate the magnetics out and use the non-
  magnetics and start off with ½ shot glass instead of a full shot. Note: This process works with free milling gold – complex
  (chemically bound) sulfides need to be oxidized for reduction to metal.
  
  SEPARATING PRECIOUS METALS: Our kilns are a tool for smelting only. There is no method for separating gold from
  silver, or other precious metals, when smelting. The ore containing the metal when melted will form an amalgam – an alloy of
  gold and silver, or whatever precious metals are in your concentrates. Let the refinery separate precious metals – it9s really
  the easiest and cheapest in the long run. You still need to have your buttons assayed to determine their purity and content.
  
  CARBON: Can gold be smelted out of carbon from a leach pad? The short answer is 8no9. If nano particles of gold are
  coated/bound up in carbon, you cannot leach it you cannot burn it, you cannot fire it.
  
  PC BOARDS: Yes, you can smelt precious metals from computer parts. Get rid of as much base metals as possible first. Cut
  the pins off the plated parts, then, do a nitric acid or hydrochloric acid digest to dissolve and get rid of as much of the base
  metals as possible before smelting.
  
  PLATINUM: Our kilns are not designed to melt platinum, as it requires temperatures in excess of 3000° Fahrenheit. However;
  you can use silver to 8catch9 platinum. Silver, which melts at a lower temperature (1700° Fahrenheit), acts as a collector metal
  and will amalgamate with platinum during microwaving. You can then do a nitric acid digest, since platinum is not susceptible
  to the acid. The silver can be precipitated from the nitric acid after recovering the platinum by adding salt to the nitric solution.
  Add salt and stir the nitric solution vigorously, then allow the solution to sit overnight. The silver will precipitate as silver chloride
  and will grow crystals in the bottom of your vessel, or a white cottage cheese looking precipitate. Better left to the refinery to
  do this.
  
  
• 
  
  SCRAP GOLD & SILVER JEWELRY: Ok guys, if you want to pour a big button and your concentrates just aren9t doing it for
  you, go out and scrounge up some scrap gold or silver and pour a really big button. The GPK kiln and flux work great for that.
  The biggest gold buttons I9ve poured have been with scrap jewelry. I take a pair of wire cutters and cut the jewelry up into
  pieces to about ¼ of an inch, add 3 shot glass measures of the flux and smelt it. I9ve poured buttons over 5 ounces using this
  method with great success. There9s not nearly the amount of impurities contained in the jewelry as when smelting
  concentrates, so the flux doesn9t get loaded up with them. The gold buttons come out with a mirror finish on them and they9re
  just amazing.
  
  STERLING SILVER: So you want to gather up and smelt silver out of old silverware? You can do that. Our white flux works
  great for that. Just be aware that sterling silver is only .925 pure. To go to .999 pure is an involved refining process beyond
  smelting. While flux will remove some of the impurities and increase the purity of the metal, you will still need to have it tested
  to determine the exact percentage of purity.
  
  STERLING SILVER PLATED: Don't even do there. Until silver reaches the price of gold, there is not enough silver on a silver
  plated fork to even begin to be worth messing with - trust me on this.
  
  POURING MOLDS: We recommend graphite molds. Heat the graphite mold to between 482°F -932°F (250°C-500°C), for a
  higher quality result. Graphite molds will last from several pours to indefinitely, depending upon temperatures and types of
  metals you are casting. (Iron, nickel and silicon are one pour only.) In event of difficulty releasing the casting from the mold,
  freeze it.
  
  PROBLEMATIC THICK AND VICOUS FLUX: Occasionally, you may get to experience having good precious metal recovery
  from your concentrates; however the flux has become overly thick and viscous and won9t pour readily into the mold, trapping
  the smelted precious metal within the flux in the mold and along the side of the crucible poured from. You can thin the flux
  slightly by adding a small amount of sodium tetra borate (Borax) to the flux prior to charging the crucible. Start slowly, dilute
  no more than 25% by volume of the flux with Borax and do so prior to charging the crucible. A better solution is to reduce
  slightly the amount of concentrates used when charging the crucible. Don’t try to add Borax to the melt when it’s hot.
  There are commercial thinners available as well.
  
  NO BUTTON: Why didn9t I get a gold button when I poured the smelted material into the mold? First of all, everyone, you
  must have gold in your concentrates to begin with and the more of it the better. For example: In a standard gravimetric
  fire assay, the lab will place 29.17 grams of the ore in a crucible along with their assay flux. After the fire assay has been
  completed by their method, they will recover the metallic bead and weigh the bead. Once the lab has determined the weight
  of the bead, they use a basic calculation that 1 milligram is representative to approximately 1 oz. of precious metal to a short
  ton of 2000 lbs. We all have a pretty good idea of what the size of a 1 gram gold nugget is - a nice picker in our gold pan - so
  we would need 1000 of the 1 milligram beads to make up that 1 gram nugget in our gold pan. A single 1 milligram bead is
  pretty small, especially when we take into the consideration the specific gravity of gold. If you9re looking at your black sand
  concentrates with a 10 power hand lens or a 30 power pocket microscope and you believe that you can see fine gold in there,
  just keep in perspective how small those gold particles actually are and how many it takes to add up to a gram or even just a
  milligram.
  The photo below on the left is from an extremely rich sample of silver concentrates that fire assayed at 9000 ounces per ton.
  The button is approximately 9 grams and reference to its size is shown by the dime beside it. If that assay button was gold
  rather than silver and the button came from a 29.17 gram sample of our cons, a single ton of our cons would be worth
  approximately $11,000,000 at today9s prices. The photo below on the right is of an assay button that weighs 375 milligrams,
  representative of 375 ounces per ton. If that button came from a 29.17 gram sample of our cons, a single ton of our black
  sand would be worth approximately $450,000 dollars at today9s prices.
• 
  

 

[Yukon99669]

It wouldn’t let me copy any text from pg4, so here’s the screenshot.

 

[Yukon99669]

Thanks for all the input everyone!



I did tidy it up a bit today. I opened up the cavity to 3/4” and went a bit deeper. Smoothed out the inside wall some. Beveled the top rim, and chopped the mounting bolt off the bottom, leaving a real nice flat and level base.


An aspect of this I’m still quite confused about…hopefully someone can explain or point me to a good explanation.

The only thing I really want to do is get the super fine gold out of my mostly panned down cons. (Mostly -100 and maybe some -70 stuff). My understanding is that I can accomplish this with Borax/Silica. This material is down to about 50/50 gold/non-magnetic black sand. A lot of the BS is dark red Garnett…..if that matters.

Somehow I keep ending up in the world of smelting and I really don’t need to get out the silver and copper.

If I go this route do I have to get to the point that everything is fully melted or is there a point where the gold had melted and separated to the bottom of the cone but the rest is still in a solid state?
I’m sure it’s a relatively easy explanation but like I said I seem to be landing in the wrong ring on this.

 

[Martijn]

Really a lot of interesting and valuable info but also somewhat contradictory: they are saying at one point: the silver and copper will be taken from the cons as base metal in the flux, in another part it's saying you can't separate silver from gold while smelting...

Extract:
There is no method for separating gold from
silver, or other precious metals, when smelting. The ore containing the metal when melted will form an amalgam – an alloy of
gold and silver, or whatever precious metals are in your concentrates. Let the refinery separate precious metals – it9s really
the easiest and cheapest in the long run. You still need to have your buttons assayed to determine their purity and content.
Or:
STERLING SILVER: So you want to gather up and smelt silver out of old silverware? You can do that. Our white flux works
great for that. Just be aware that sterling silver is only .925 pure. To go to .999 pure is an involved refining process beyond
smelting. While flux will remove some of the impurities and increase the purity of the metal, you will still need to have it tested
to determine the exact percentage of purity.

So i think it( the black flux) can also take traces of silver and copper from nearly pure gold, but still not all. Leaving you with a product that still has to be refined.

And to melt pure metals, flux is not needed at all. It's a sales thing.

I know you want results fast, but this is quite complex matter.
So if you want to get pm's from 50/50 black sand cons you really need to smelt and use flux. A cone mold will concentrate any metal into a small point when pouring.

Binge watch mbmmllc. It explaines a lot. The guy is almost going scientific on this matter.
https://youtube.com/c/mbmmllc
To get an idea of whats in your cons smelt with an excess of flux as the manual describes, and get it xrf analyzed for the best representation of whats in your test samples.

If this flux is the right one for you, or if you could just mix soda, borax and silica in a certain ratio, not sure and you'll need to figure that out by getting experience.
I would not base a buisiness plan on home made assay results if i wasn't sure it's done properly.
Good results can only mean a GO, with bad results you don't know if it was the sample or your process that that caused it.

Martijn.

 

[Martijn]

Another thing: if you can't get an assay done or perform the steps to extract ultra fine gold, exept by smelting, how will you mine the claim? Will smelting all those cons be profitable?

 

[Martijn]

Like this one