Pre-treatment before incineration

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mjgraham

Well-known member
Joined
Feb 11, 2012
Messages
217
Location
Pennington Gap, VA
Hi, I have been working with the left over pieces of metal from burnt ICs, the legs and innards, my first step was to put them in HCl to remove all but copper and above and do an incineration then do a nitric leach then to AR. My question is what is the best way to go from HCl to incineration? I rinse it all well with hot water but when things get incinerated (small test) seems like I get some material that nitric doesn’t touch, I know it should mostly be copper but I get a green solution kind of like copper in AR. I keep it all at red heat for a little while but other than melting it to make sure, I want to think that someone mentioned rinsing it with NaOH to get the ph back toward the middle before incineration but I wanted to ask and see.
Thanks
Jarrid
 
Jarrid,
I am the guilty one, who mentions washing in sodium hydroxide NaOH, after using HCl before incinerating the material.

Just so others understand what we are talking about,some times we use HCl to remove a metal, like tin Sn solder, and then later we wish to use nitric acid HNO3 to remove other metals like copper Cu, but we do not want to dissolve gold Au yet, so in order to not dissolve gold we will have to incinerate the material to remove traces of HCl or the chloride salts in the material(remember a metal and an acid will make salts of that metal and acid), these salts which if left would create a form of aqua regia that would dissolve some of our gold with base metals when we used nitric acid next, to keep from doing this and losing gold in this step we incinerate the material before moving from HCl to nitric acid, the incineration and high heat drives off liquids and salts, the chlorides as gases, bringing the material up to the red hot roast in air, and stirring, and good exposure to air for a period of time, can also help to oxidize the base metals making acid treatments a little easier to dissolve those metals and metal oxides in later acid treatments.

Now back to the question of washing In a solution of water and sodium hydroxide NaOH, my reasoning here comes from a simple thing, gold or silver if roasted with chlorides even table salt, some of the gold or silver can be made volatile, at high temperatures, (remember when things are heated strongly or melted chemistry is going on inside and acids or salts can become stronger gases can form which also can have have effects on the chemistry in the process), the chlorine formed at high temperature will dissolve gold, and a little of the gold can be carried off as these gases escape, as the volatile gold chloride at these temperature, so my reasoning here for the NaOH wash is this when HCl and NaOH come together they form NaCl and water, NaCl (table salt) sodium chloride is water soluble and can be washed from the powders, this also neutralizes the HCl acidic nature, and can also help with some metal powders like silver chloride to form silver oxides, which can be roasted with out lose, as opposed to silver chloride which can be lost in the smoke when heated strongly, so after the NaOH wash it is also important to give the material several water washes to dissolve and wash out the NaCl salts that form (HCl + NaOH --> NaCl + H2O).


I will normally do this treatment in a casserole dish on a hot plate, leaving the material in the dish and decanting washes from the material only after it has settled well, to decant I use a suction bulb tool and a pipette, the washes are heated and stirred well, to help with conversion and dissolving, the material can be dried and incinerated in the dish, then we could do another water wash after the incineration and cooling, and move on to later treatments like nitric acid...

I will treat my material many times in the corning casserole dish, almost from beginning to end of the process, without hardly ever removing the material from the dish (except for maybe steps like screening or filtering, leaving undissolved material in the dish, and decanting the liquids of dissolved metals or rinses throughout the process, also giving the insoluble powders time to settle before decanting solutions, many times these decanted solutions are moved to settling jars where insoluble material in the wash or solution can settle theses powders may also contain traces of value, other times the solutions are decanted with the suction bulb and are either screened or filtered into a clean jar for settling and or re-filtering again later.

powers are also crushed in this dish I have a large piece of boiler sight glass (Pyrex) that works good as a glass pestle, the casserole dish acts as my mortar.


On an unrelated topic of tin removal, incineration of powders which had tin involved, the incineration process, helps to convert tin chlorides, or other tin salts, to tin oxides, which are more easily dissolved in a boiling wash of HCl, and then rinsed in boiling hot washes to help remove lead chlorides,.
The incineration process, also helps to remove organic material,that can cause problems,filter paper, glue, oils, John's sandwich...
 

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butcher said:
Jarrid,
I am the guilty one, who mentions washing in sodium hydroxide NaOH, after using HCl before incinerating the material.



Now back to the question of washing In a solution of water and sodium hydroxide NaOH, my reasoning here comes from a simple thing, gold or silver if roasted with chlorides even table salt, some of the gold or silver can be made volatile, at high temperatures, (remember when things are heated strongly or melted chemistry is going on inside and acids or salts can become stronger gases can form which also can have have effects on the chemistry in the process), the chlorine formed at high temperature will dissolve gold, and a little of the gold can be carried off as these gases escape, as the volatile gold chloride at these temperature, so my reasoning here for the NaOH wash is this when HCl and NaOH come together they form NaCl and water, NaCl (table salt) sodium chloride is water soluble and can be washed from the powders, this also neutralizes the HCl acidic nature, and can also help with some metal powders like silver chloride to form silver oxides, which can be roasted with out lose, as opposed to silver chloride which can be lost in the smoke when heated strongly, so after the NaOH wash it is also important to give the material several water washes to dissolve and wash out the NaCl salts that form (HCl + NaOH --> NaCl + H2O).


I will normally do this treatment in a casserole dish on a hot plate, leaving the material in the dish and decanting washes from the material only after it has settled well, to decant I use a suction bulb tool and a pipette, the washes are heated and stirred well, to help with conversion and dissolving, the material can be dried and incinerated in the dish, then we could do another water wash after the incineration and cooling, and move on to later treatments like nitric acid...

I will treat my material many times in the corning casserole dish, almost from beginning to end of the process, without hardly ever removing the material from the dish (except for maybe steps like screening or filtering, leaving undissolved material in the dish, and decanting the liquids of dissolved metals or rinses throughout the process, also giving the insoluble powders time to settle before decanting solutions, many times these decanted solutions are moved to settling jars where insoluble material in the wash or solution can settle theses powders may also contain traces of value, other times the solutions are decanted with the suction bulb and are either screened or filtered into a clean jar for settling and or re-filtering again later.

powers are also crushed in this dish I have a large piece of boiler sight glass (Pyrex) that works good as a glass pestle, the casserole dish acts as my mortar.


On an unrelated topic of tin removal, incineration of powders which had tin involved, the incineration process, helps to convert tin chlorides, or other tin salts, to tin oxides, which are more easily dissolved in a boiling wash of HCl, and then rinsed in boiling hot washes to help remove lead chlorides,.
The incineration process, also helps to remove organic material,that can cause problems,filter paper, glue, oils, John's sandwich...
Click to expand...


That's exactly how i intend to do my stock pot residues. Right down to the Pyroceram dish.
I haven't had the pleasure of stock pot processing yet so this should be interesting.

On a side note I've also been thinking about building a small filter press that could be used for a small refiner like myself. I think it would be a good project and i'm going to build it with off the stock items from Lowes so it's easily replicated. Not really that complicated i'm thinking. Maybe a piece of 3 in pvc pipe about a foot long with some kind of couplings and attachments where off the shelf filter papers can be used. The plate for the filter paper and then an air coupling on top of the tube where an air compressor could be hooked up to apply air pressure. You wouldn't need anything bigger than a small air compressor to pressurize the vessel and that's it. It's an idea anyway.
 
I thought about a plunger type system where it could be inverted and the solids settle on the bottom or plunger as it rises up a column. The benefit would be that the filter plate would be at the top and be less likely to clog as quick. The down fall is the seals to pressurize the cylinder without leakage. Plus a plunger or cylinder like that can only compress the solids so far leaving them still substantially wet. With the upright cylinder using air pumped into a pressurized column the air builds above the column forcing down on the liquid like a plunger would but able to extract near complete liquid removal. Simple design with no moving parts. Basically a reverse buchner funnel operated on air instead of vacuum. Not sure of the design yet.
 
Teflon "O" rings are very acid resistant. you can get them in any size at where ever rubber seals are sold.
 
It's hard to get a good seal against the inner walls of PVC pipe because it's not smooth on the inside like it is on the outside. The outside diameter of PVC pipe is made to close tolerances so it can be properly glued into the various fittings. For it's designed purpose in plumbing, the inside dimensions and finish aren't as critical. So the outside is smooth and consistant, but the inside is kind of lumpy and bumpy - not enough to affect the waste that drains through it, but not the nice, smooth bore you need for the inside of a close fitting piston cylinder.

But if the material you want to press were contained in a bag of filter material, and the piston head made just small enough to fit into the pipe - not a tight seal to the inside surface of the pipe, but close enough to not let the filter bag squeeze between the pipe wall and the head of the piston, you might enjoy some success.

I would model it on the old-fashioned fruit presses. The fruit is crushed and the pulp loaded into a fabric bag. The bag sits inside a "cage" made of wooden slats with space between each slats. The top of the bag is closed and the "piston" presses down on it. The juice flows out between the slats. It doesn't depend on a close tolerance between the piston and the inside of the cylinder. The bag is the key to keeping the pulp contained.

Dave
 
a spring loaded automotive cylinder bore would smooth the walls. i would call it a trial and error process until you get a finished piece that would work.
 
Well that all makes sense to me, thanks for the detailed information, I thought it might have been you butcher but I didn't want to call anyone out on it. As per normal it seems I read a bit of info and when I try to go back and find it I never can, and it looks like a side development may be going on to.
Thanks again
Jarrid
 
I built something like this out of 4" pvc pipe. I used rubber fitting with band clamps to hold caps on the ends, with a schrader valve on the top cap. The valve was band clamped in a pvc hose which was poked through a tight, clean hole in the cap. The bottom cap was perforated with many 1/8" holes. For filtering I would take the bottom perforated cap, make a bed of toilet paper in it and prewet it so it would stay in place. Then I would invert the apparatus, and fill through the open filtering end of the 4" pipe, place the filtering cap back on, tighten the clamps and quikly invert the apparatus. That way there wasn't any pouring dislodging the filtering toilet paper. Then pressurize. The rubber clamps don't hold a lot of pressure, i would only put in enough to bulge the rubber fittings slightly. Too much and the end would shoot off (I always applied the pressure in a bucket in case of this).
Anyways it could use some tweaking, but it worked quite well and fairly rapidly for filtering any haze out of my cat converter solution. Some better fittings would be nice, but this was off the shelf and working quickly. I made mine 6' tall and it held a couple gallons, but it could be any size. I hope someone can use some of this and improve it!
 

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