Types of material I would refine

[4metals]

Mod,

I made up a spreadsheet to crunch these numbers and if you take the small cell up to 120 g/l copper running .925 sterling, you should be able to pump out 2000 ounces of silver with under 1% copper in it as a contaminant. Less in the beginning and more at the end. Rinsing electrolyte from harvested cells is your friend. What is nice is 10 gallons of cell solution is easy to handle for cementing and waste treating, and depending on how fast you can push the 2000 ounces through you may need a few running.

The "high grade" cell starting with the silver you made in the smaller cell will process 15 times as much silver of high purity before the 1% copper fouls the electrolyte. The foul electrolyte from the high grade cell will still function in the smaller cell to further raise the copper before changing it out. Less waste = more profit.

Remember the second cell will function better if you add some copper to start as the feed silver will provide little.

 

[goldsilverpro]

I most certainly would not make a silver cell from stainless or any other metal.

 

[4metals]

My first choice would be PVC and a stainless cathode.

Interestingly there are members here who have had good luck using the 1 gallon stainless bowls though. But for a production deal, I would agree.

 

[Lou]

I used plywood and titanium sheet as the cathode and made the boxes out of polypropylene and fiberglass rod for support.

I folded up the cathode and punched a hole in it and bolted the 000 wire lead in between some 1/2" copper bus bar. They ran well.

Lou

 

[Barren Realms 007]

I used plywood and titanium sheet as the cathode and made the boxes out of polypropylene and fiberglass rod for support.

I folded up the cathode and punched a hole in it and bolted the 000 wire lead in between some 1/2" copper bus bar. They ran well.

Lou

If you know someone whit the experience they can weld the poly tanks up for you.

 

[Lou]

We have heat and ultrasonic welder at the plant for welds CPVC (our exhaust), PVDF (socket welds for nitric or Aqua Regia duty valves), and the polyolefins (low temp tanks, <50 C).

I made the box from plywood and marine epoxy. Works as well as any poly tank at much less of a price.

Our Mob cells are polypropylene.

 

[Barren Realms 007]

We have heat and ultrasonic welder at the plant for welds CPVC (our exhaust), PVDF (socket welds for nitric or Aqua Regia duty valves), and the polyolefins (low temp tanks, <50 C).

I made the box from plywood and marine epoxy. Works as well as any poly tank at much less of a price.

Our Mob cells are polypropylene.

Marine epoxy. I need to do some searching on that unless you wold be willing to supply some link'sto some information on this.

 

[4metals]

I believe he means fiberglass resin, the vinyl ester resin holds up well in fabrication of hoods and scrubbers and large tanks.

Here is a comparison of epoxy resins and vinyl ester resins.
Advantages and Disadvantages

On a broad scale of viscosity, vinyl esters are midway between polyesters and epoxy resins, before adding styrene. Thinning affects workability and strength - 'thinning' reduced strength but makes it easier to brush or spray.

Vinyl esters are more tolerant of stretching than polyesters. This makes them more able to absorb impact without damage. They are also less likely to show stress cracking.

Vinyl ester has fewer open sites in its molecular chain. This makes it much more resistant to water penetration ('hydrolysis') which can cause osmotic blistering.

Vinyl esters shrink less on curing, which means that 'pre-release' of a laminate from a mold is less significant.

The cross bonding of vinyl esters is superior to that of polyesters. This means that vinyl esters bond to core materials much more effectively than polyesters and delamination is less of an issue.

Vinyl esters are less sensitive to ambient conditions (temperature and humidity) than are polyesters.

Vinyl esters are more expensive than polyesters though careful calculations are required to assess the cost impact for a significant build project such as a luxury yacht. This is because the relative strengths need to be factored in - you can use less vinyl ester to achieve a given strength.

PLus I like it from my surfboard building days!

 

[Barren Realms 007]

I believe he means fiberglass resin, the vinyl ester resin holds up well in fabrication of hoods and scrubbers and large tanks.

Here is a comparison of epoxy resins and vinyl ester resins.
Advantages and Disadvantages

On a broad scale of viscosity, vinyl esters are midway between polyesters and epoxy resins, before adding styrene. Thinning affects workability and strength - 'thinning' reduced strength but makes it easier to brush or spray.

Vinyl esters are more tolerant of stretching than polyesters. This makes them more able to absorb impact without damage. They are also less likely to show stress cracking.

Vinyl ester has fewer open sites in its molecular chain. This makes it much more resistant to water penetration ('hydrolysis') which can cause osmotic blistering.

Vinyl esters shrink less on curing, which means that 'pre-release' of a laminate from a mold is less significant.

The cross bonding of vinyl esters is superior to that of polyesters. This means that vinyl esters bond to core materials much more effectively than polyesters and delamination is less of an issue.

Vinyl esters are less sensitive to ambient conditions (temperature and humidity) than are polyesters.

Vinyl esters are more expensive than polyesters though careful calculations are required to assess the cost impact for a significant build project such as a luxury yacht. This is because the relative strengths need to be factored in - you can use less vinyl ester to achieve a given strength.

PLus I like it from my surfboard building days!

Yea that would make sense now that he was talking about fiberglass resins.

Fiberglass held up good for the majority of the time and operations at our chemical plant. When heat is added to the fluids it seems to break down the resins faster though. so this would be one of the areas to consider when using fiberglass.

 

[Lou]

No, both of you. I meant an actual epoxy not a polyester or vinyl ester (kind of a hybrid between the two really, so I see the confusion).

This should answer some questions:

http://www.masepoxies.com/file/About%20Epoxies%20.pdf

Not saying that either wouldn't work, which they would. Fluoridated "novolac" epoxies are perhaps the best in terms of corrosion resistance.

 

[Barren Realms 007]

No, both of you. I meant an actual epoxy not a polyester or vinyl ester (kind of a hybrid between the two really, so I see the confusion).

This should answer some questions:

http://www.masepoxies.com/file/About%20Epoxies%20.pdf

Not saying that either wouldn't work, which they would. Fluoridated "novolac" epoxies are perhaps the best in terms of corrosion resistance.

Clarify the marine epoxy with an example please.

 

[4metals]

Lou,

With the vinyl ester resins I always used fiberglass chopstrand mat or cloth, actually both mat for the flat surfaces and cloth strips for the corners.

Does the novolac epoxy require fabric? Actually the vinyl ester resin doesn't "require" fabric but it is much stronger with it. Novolac epoxies are the self leveling floor coating epoxies I use on refinery floors for containment purposes.

 

[Lou]

https://www.amazon.com/AeroMarine-300-Epoxy-Resin-Gallon/dp/B0047R2C9Y?ie=UTF8&*Version*=1&*entries*=0

That's what I mixed and put over the wood and worked great. I put two or three coats down. Generally speaking, epoxies have more corrosion resistance than vinyl esters which have more corrosion resistance than polyesters (which are really susceptible to base hydrolysis).

None of them require fabric or prepregs but pretty much all of them can be employed with them to make a composite having properties better than the individual components (resin and filler).

Self-leveling has to do with their viscosity when employed (be it from the precursors, as most of these are two or even three part and not UV-catalyzing, or from fillers like alumina), not whether it's a novolac--although you're spot on that all novolac's are quite viscous due to hydrogen bonding of phenol functionalities, steric effects etc. I consider novolac an arcane term mostly related to the precursors, which are aromatics like substituted cresols often made from destructive distillation of I'm guessing, pine lignin. They are quite chemically resistant and are usually very highly cross linked, which act like bridges to the other part of the structure.

The degree of flexibility (along with most of its physical properties) in a coating has much to do with the way the molecules interact with each other, such as bond strength/length, whether or not the material is cross linked, presence of pendant groups that may entangle with one another. While this discussion as to the differences in epoxy resins vs polyester and polyvinyls can be very complicated, I'll try and sum up the main difference:

An epoxy is not a polyester--epoxies form by the ring opening of an epoxide (which is a stressed cycloether) and have entirely different linkages and polymerization mechanism.

A polyester, say Nylon, is by taking a polyol, in this case a diol and reacting it with a di-acid (or acyl/aryl halide) in a polyesterification. This is a condensation reaction and water (or HCl, if an acyl halide as in the case of Nylon) is produced as a product.

While I do work in precious metals, I did go to school for polymer and materials science and my little sister works in the R&D department at Sherwin Williams doing Protective and Marine Coatings as a chemist--she really has a lot more real-world expertise than I do.

 

[4metals]

Interesting Lou, thank you for the link.

The first hood I ever made was plywood with resin painted on, pretty thick actually but no fabric. It lasted until it was moved to a new building and the jostling cracked some of the seams. I would probably have never noticed except for the fact that the seams that cracked were on the bottom perimeter and functioned for spill containment, and the leak was in the front where it dripped, of course, on my shoes, so I noticed it. (Actually the wife noticed it, I always had a knack of burning holes through clothes!)

Since then I always used fabric.

Maybe you could get a recommendation from little sis for a (spray on?) coating to transform relatively inexpensive metal blowers into something that has a fighting chance with refining hood exhaust. Now that is something a lot of our members would benefit from. I mean Sherwin Williams goal is to cover the earth. We can help do it one refining hood at a time!

 

[Lou]

I know what we used for our steam table at work and it's holding up to aqua regia vapor. We put it over SS316L:

Two coats of Sherwin Williams DuraPlate II epoxy. They can even put it over plywood. That was her recommendation.


Anyway, the most important thing of any coating is the surface preparation. Period end of story. Don't have a good surface for it to adhere onto, it's going to spall. Some things are more tolerant than others but substrate preparation is paramount.

 

[Barren Realms 007]

Interesting Lou, thank you for the link.

The first hood I ever made was plywood with resin painted on, pretty thick actually but no fabric. It lasted until it was moved to a new building and the jostling cracked some of the seams. I would probably have never noticed except for the fact that the seams that cracked were on the bottom perimeter and functioned for spill containment, and the leak was in the front where it dripped, of course, on my shoes, so I noticed it. (Actually the wife noticed it, I always had a knack of burning holes through clothes!)

Since then I always used fabric.

Maybe you could get a recommendation from little sis for a (spray on?) coating to transform relatively inexpensive metal blowers into something that has a fighting chance with refining hood exhaust. Now that is something a lot of our members would benefit from. I mean Sherwin Williams goal is to cover the earth. We can help do it one refining hood at a time!

Back many years ago we had a 4" steel pump that we had to keep going till we got a hastaloy pump in for the process circuit if my memory serves me right. We were able to find a ceramic that we were able to pain onto the inside of the pump to make it last till we got the new pump in. That might be an option you could check into.

 

[Lou]

If you went from steel to Hasty B or X I'm guessing it was caustic service. The ceramic was probably zirconia--very base resistant and acid resistant.

 

[Barren Realms 007]

If you went from steel to Hasty B or X I'm guessing it was caustic service. The ceramic was probably zirconia--very base resistant and acid resistant.

It was B that we were waiting to come in to replace the existing pump. And it wasn't caustic. Were were producing zinc chloride and zinc bromide from plating wastes. They were using HCL & HBR acids to leach the zinc out of the plating wastes. It might have been a zirconia base ceramic I'm not sure because at that time I was not involved in the refining field and didn't pay as much attention to the make up of the ceramic coating make up as I would do now days.