Sciencemadness Discussion Board

Check out this video on melting lead - is this "dross" or oxide?

RogueRose - 3-11-2018 at 01:17

So this guy goes through all kinds of steps trying to purify his lead, placing candle wax into the molten lead (to release the "dross") and then he keeps scraping the surface (like 40 times) to remove the very thin layer of "dross" (I think it's normal oxide).


Go to about 27:30 in the video, once he removes the obvious dross he then starts dropping in candles and such.
https://www.youtube.com/watch?v=fTRwfyvIbkc


1.5 million views and I'm thinking this wax doesn't remove dross but helps with the oxidation layer which he is calling dross. IIRC, somthing like sawdust would work as well and would burn slower. Sawdust would work especially if pouring from the bottom of the pan through a spout.

Ubya - 3-11-2018 at 04:02

i've heard of people using wax, oil, sawdust and even car tires, just anything that stops oxygen from reaching the molten lead

i have maybe 10kg of "dross" and corroded lead batteries electrodes, i'm planning on turning everything back to lead metal by real smelting (i don't know why people say "smelting" lead when they are just melting it)

Tsjerk - 3-11-2018 at 05:46

Quote: Originally posted by Ubya  


i have maybe 10kg of "dross" and corroded lead batteries electrodes, i'm planning on turning everything back to lead metal by real smelting (i don't know why people say "smelting" lead when they are just melting it)


In dutch "smelting" sounds like "smelten", which literally means melting. I don't know why people use the term smelting in English but it might be because it means something else in other languages.

fusso - 3-11-2018 at 06:25

I'm very sure dross is mixture of Pb oxide+other impurities. He obviously can't distinguish between dirt and oxide. He kept scraping the shiny surface to make more oxide thus wasting lead and creating more waste just drove me crazy:mad::mad::mad:

[Edited on 181103 by fusso]

Fulmen - 3-11-2018 at 07:22

Wax does separate dross from the metal quite effectively. The oxides sticks to the metal, allowing quite large particles to be caught below the surface. The wax absorbs into the oxides, breaking the wetting effect.

RogueRose - 3-11-2018 at 22:28

Quote: Originally posted by fusso  
I'm very sure dross is mixture of Pb oxide+other impurities. He obviously can't distinguish between dirt and oxide. He kept scraping the shiny surface to make more oxide thus wasting lead and creating more waste just drove me crazy:mad::mad::mad:

[Edited on 181103 by fusso]


Ok, that is what I thought as well. I didn't know if I had misunderstood what the surface layer was or not. I thought it was oxide but wasn't sure.

Melgar - 4-11-2018 at 14:05

Wax protects the surface from oxygen, but also can reduce lead oxide to metallic lead at high enough temperatures. It's also probably the best thing you can use since it would float on the surface, doesn't catch fire very easily, and is made entirely of hydrogen and carbon. It's also pretty cheap and easy to remove any residues. Sawdust would leave ash behind, which is mostly silicates and carbonates from groups I and II.

[Edited on 11/4/18 by Melgar]

fusso - 5-11-2018 at 09:09

Quote: Originally posted by Melgar  
Sawdust would leave ash behind, which is mostly silicates and carbonates from groups I and II.[Edited on 11/4/18 by Melgar]
Why's there silicate in woodash?!

kulep - 5-11-2018 at 10:14

Quote: Originally posted by fusso  
Quote: Originally posted by Melgar  
Sawdust would leave ash behind, which is mostly silicates and carbonates from groups I and II.[Edited on 11/4/18 by Melgar]
Why's there silicate in woodash?!


stronger and more abrasive plants aren't eaten that easily by pesky animals, grasses usually have high silicates contents tho, I don't know so much about wood.

rice hulls for example have a veeery high silicate content

"Rice husk was found to have lower extractives content and higher ash content, in comparison with other residues. The high ash content is associated with a large amount of silica (SiO 2 ); the analysis detected 8.32% of silica."
CHARACTERIZATION OF RESIDUES FROM PLANT BIOMASS FOR
USE IN ENERGY GENERATION

[Edited on 5-11-2018 by kulep]

Fulmen - 5-11-2018 at 10:20

Iirc the bark is usually rich in silicates, I suspect it's part of it's fire resistance.