dreamers?

[arthur kierski]

a guy send me a piece of copper(180grams) and says:by x-ray this piece has --5,8%rh---7,8%pd---12%ag----and smallpercentage of au and ir----what i dout this piece in 42%nitric and heat it----after dissolving the piece it becomes 7grams and to the liquid i add nacl----result no ag,them my standard pd test---result no pd---i am already frustrated and the guy fones me and ask if i have some results-----i take the 7grams left and do an ap attack__it dissolves and go with hidrazine and form a brown powder which i suspect is gold ---add hcl and it dissapears----it is not gold but iron----things like these happens often to me-------
question:am i incompetent---doing some wrong chemistry or are these guys dreamers who think(dreams) that they have mines full of pm and in their dreams involves suckers like me???

 

[goldsilverpro]

Sounds like you did things OK, chemically. However, what do you tell him about what happened to his $3000 worth of rhodium? For this reason, I don't think you should have done the whole bar. A 5 gram drilling sample (that you drill yourself) would have been enough to give you the same information. You must cover your butt. This could be a con. Also, if he is mad, it could hurt your reputation.

Mark Twain defined a gold mine as a hole in the ground owned by a liar. The problem is, most don't lie intentionally. They really believe in their stuff. And, over time, it gets bigger and bigger. And, they never believe it when you tell them their stuff is worthless.

I spent 2 years, in Oregon, dealing with amateur miners and prospectors on almost a daily basis. I evaluated their material, helped them with processes, and listened to their long stories. It was fun for awhile, but at least 98% of them had nothing, although they all thought they were rich. Nice people, but I vowed to never deal with them again.

 

[Platdigger]

I have two questions.

1. Wouldn't all of the (or any) iron have been taken up by the nitric?

and

2. Wouldn't something (even a precious metal) you just reduced out of a HCL solution with hydrazine (especially if the PH was adjusted to cause this drop).........be easy to put back into solution with more HCL?

Randy

 

[arthur kierski]

gold pro, today talking with my brother in law i made the same promise that you did--i vowed not to help any one who cames to me with ore saying that the ore has these or that percentage of pm---the guy does not no the diference of rh from silver---

 

[arthur kierski]

randi,usually nitric acid passivates iron and because of this it remains as a metal---------hidrazine at 80centigrate with a drop of naoh precipitates metals----whem the metal ( Black powder =pgm or brown gold ) is precious it does not dissolve with hcl or h2so4 when added,but iron copper ,nickel which precipitates with hidrazine as oxides or hidroxides solubilize instantly when these acids are added

 

[Harold_V]

I spent 2 years, in Oregon, dealing with amateur miners and prospectors on almost a daily basis. I evaluated their material, helped them with processes, and listened to their long stories. It was fun for awhile, but at least 98% of them had nothing, although they all thought they were rich. Nice people, but I vowed to never deal with them again.

People that you described were the worst I ever encountered, and very commonly very poorly informed. I also found them to be very untrusting and having expectations that were far beyond reason. There were few exceptions.

A good example is one demanding that his placer gold contained no silver or copper, doing his best to explain to me that it had no need to be refined. In his mind, he had pure gold-----it just needed to be melted------which, to him, apparently, was refining.

Heavy sigh!

VERY heavy sigh!

Harold

 

[sags]

I'm late to this topic, but just reading through some old ones to learn.

Arthur, I don't think Nitric will passivate Iron or steel, it will dissolve it and release a very toxic fume of Nitric Oxide.

 

[goldsilverpro]

Nitric, of course, will passivate most forms of stainless steel. Undiluted nitric will tend to passivate some forms of regular steel. With the addition of water and/or heat, it will attach the steel. An addition of potassium dichromate to a more dilute nitric will tend to prevent attack on the steel.

A story. In the late '60s, I consulted for a large, 200 employee, plating shop in L.A. At the time, many of the gas stations gave away gold plated 410 stainless flatware (knives, forks, spoons, etc.) with gas purchases. This plater was plating about 250,000 pieces per week. Once, he shipped about a million pieces to Hawaii. They became exposed to a salty atmosphere on the boat ride over and corroded. Thin plating is porous and the corrosion appeared as about 1/8" brown rings around the pores. The customer demanded that, after the parts were repaired, they be 100% subjected to standard salt spray testing before shipping. The only way (or, so it seemed) to repair the situation was to strip and replate the parts with thicker gold, which would have cost the plating shop owner a fortune and could have bankrupted him. I did some experiments and came up with a dilute nitric/dichromate dip instead. It dissolved the brown ring (rust) and, at the same time, it passivated the stainless exposed by the pores. It passed the salt spray test 100%. I got a nice bonus.

 

[sags]

nice job on the save and bonus!!

Be carful of concentrated Nitric, it will absorb moisture from the air and eventually attack the steel, resulting in corrosion of your part. I don't believe concentrated Nitric Acid however can passivate any Steels, even some of the high hardned, low chrome alloys will rust fairly fast after removing from concentrated Nitric. Even some of the 400 series Stainless Steels will corode in any conditions of Nitric.

 

[scwiers]

Isn't that why most tech grade nitric sold in North America treated with a trace amount of Hydrofluoric--so that they can ship it down the highway in shiny SS tankers?

And, while on the halides: in doing a halide extraction, it helps to create a solution of brine, right, even before adding HCl and oxidizer? Since pretty much any intuition I've ever had about the chemical realm gets turned inside out at this site, it only stands to reason, that brine *must* make metals more soluble under HCl (aq) and oxidizing conditions.

--Sam

 

[goldsilverpro]

I'm not convinced that Tech. grade or reagent grade nitric will absorb water. If it does, it must be very minor - nearly unmeasurable. Sulfuric is another story. I used to use conc. sulfuric in a desiccator to dry precipitates in Gooch crucibles for gravimetric analysis.

The addition of HF to tech grade nitric sounds a little phony to me. When you buy nitric, you buy nitric. A little fluoride ion could screw up a lot of industrial processes. It also might damage the passive metallic oxide film created on the SS by the nitric.

 

[arthur kierski]

take a piece of iron and put in a nitric solution and then tell me the results--if you dissolve all the piece , i apologise for my reply to platdigger-- if you do not dissolve it--i will call you one of the dreamers that i described in this thread

 

[Harold_V]

Isn't that why most tech grade nitric sold in North America treated with a trace amount of Hydrofluoric--so that they can ship it down the highway in shiny SS tankers?

I know nothing about chemistry, but having worked as a machinist for the bulk of my life, with considerable time spent in defense work, I know that 300 series stainless is passivated with heated dilute nitric and potassium dichromate. There is no need for HFl as far as I know.

Harold

 

[Harold_V]

take a piece of iron and put in a nitric solution and then tell me the results--if you dissolve all the piece , i apologise for my reply to platdigger-- if you do not dissolve it--i will call you one of the dreamers that i described in this thread

Many years ago I was a collector of insulators. Included in my collection were sections from high voltage insulators, seen hung in strings from distribution lines. They are made, typically, with a steel attachment knob that is cemented to the top of the saucer shaped insulator. The projection on top formed a cavity on the bottom, which allowed for the installation of the hook that was used to assemble the insulator strings. To remove the heavily galvanized steel components, these saucers were soaked in dilute nitric acid, which dissolved them totally within a few days. even with cold acid. I know now that HCl would likely have been a better choice.

Harold

 

[goldsilverpro]

Once we had many, many drums of aircraft bearings made of mild steel. The bearing surface was silver about 1/16" thick. If I remember right, there was a layer of lead or tin on top of the silver. I was trying to develop a chemical method to strip the silver without attacking the steel.

The first thing I tried was an electrolytic cell using sodium nitrate. It was OK but too slow.

Next I tried soaking in technical grade nitric. It was also pretty slow and, at full strength and room temp, the steel wasn't attacked. To speed it up, I added a little water. After adding about 3 or 4 percent, the acid vigorously attacked the steel. The nitric sort of worked but it was very touchy.

We ended up buying a lathe, chucking a pair of bearings into it, and cutting off the silver.

 

[AuMINIMayhem]

as far as I know, HF is predominantly used for etching glass. Nasty, nasty stuff and the thought of it being in any concentration in anything marked other than HF scares the sh__ outta me.. :shock: (ie: brake dust cleaner.. yup, some has HF in it.. also the "spot free rinse" at a LOT.. I mean A LOT of self service car washes also has dilute HF in the water..)

In the optics place I worked in we had a hatchet that was pleasantly mounted above a shelf in the room we did the etching in.. I asked about it one time and was told (I'm sure it was somewhat tongue-in-cheek) it was the best way to "treat" an HF exposure.. of course, naturally the shelf below contained all the Calcium Gluconate gels, etc..



Derek

 

[Shecker]

HF is series death if a mistake happens. One drop on the skin creates a reaction with calcium in the tissues and bones. The more calcium encountered the worse the reaction becomes and once it eats into the flesh and finds bone the reaction can cause the loss of an arm (as an example).
I considered using fluoroboric acid once (a mixture of hydrofuoric and boric acids) as a pgm leach, read the MSDS on HF, and dropped the idea right there. I know when to leave potential death alone. I don't play with rattlesnakes either, although I didn't see that Black Widow spider that one time that had a home in a leach tank. When I went to use the tank it got me.

Randy in Gunnison

 

[AuMINIMayhem]

:shock: yikes... black widows...


yeah I got tagged on the knee by a brown recluse when I was a kid, got a decent scar from that one.

I had an HF related exposure a couple years back, so I'm reallllllly familiar with the stuff.. LOL!.. that's why I throw up the red flag when I hear it being mentioned..

luckily what I was exposed to was Alodine (1401?) it has like 0.01% HF in it.. something like that, which is still enough to make them panic at the ER :shock: :lol: but the stuff we have here and the previous optics place I worked at is 100% HF.. scary stuff to say the least..

the problem is, it doesn't burn the skin, it migrates straight past the soft tissues and takes out the calcium in your bones and yes the calcium in your blood which is one of those nifty little electrolytes your body needs to conduct the proper charge to pulse your heart.. good stuff.. glad I'm not the only one wary of that stuff.

Like I said in my last post.. you want to read something really scary? Google "Hydrofluoric Acid and car washes" :shock:

http://www.carwash.com/article.asp?IndexID=4230101

great stuff for cleaning glass at the right solution tho..

 

[Lou]

100% HF?! That seems a bit high! Most etching solutions never run above 40%, even for quartz. 100% HF and 40% concentration are night and day difference. One will fume profusely in air and is very easily spilled (a mobile liquid, doesn't stick to things), the other is just a very dangerous water

FYI Randy, Fluoroboric acid is a better substitute for HF, at least in terms of safety (much less volatility, less danger of action on the skin).

HF is very useful, if it is used correctly. It has some applications in refining.

 

[AuMINIMayhem]

Lou... we do a bit more than etching here

Plus what we're etching is pretty hard stuff SiC (Silicon Carbide).. they don't use it at 100% they mix it down, but it's still more than 40% by the time all is said and done.. we make precision optics and mirrors for satellites, so everything is very tightly spec'ed out.

On a side note.. our chemical guy is SCARY..LOL! The one person who has access to the HF here is ummm... well, let's put it this way, I'm no the most sure-footed guy around town, but this guy makes me look graceful :lol: :lol: :lol: