Talk:Gold extraction

Mercury

My understanding is that a good deal of the mercury in gold ores today actually is from amalgamation. It's not that amalgamation is used today, it's the fact that the old miners left a lot of mercury behind when they were going after the free gold 100+ years ago. This article needs a lot of work! BSMet94 06:54, 18 January 2007 (UTC)

Another thing about mercury: the article states that it's removed from electrowinning cathode material or Merill-Krowe precipitates by retorting. I'm not aware of any examples of retorting the steel wool cathodes prior to smelting. Retorting was the process used when mercury was intentionally used to recover gold by amalgamation. I'm not sure that mercury contamination of electrowinning and Merrill-Krowe intermediate materials is a problem at all (I doubt it). Someone enlighten us. Definitely, mercury contamination of tailings and gaseous emissions from gold ore roasters is a real concern that is dealt with in operating gold plants. I have limited knowledge on Hg disposition in gold recovery. Can someone please clarify this section of the article with some better technical details?BSMet94 20:26, 22 January 2007 (UTC)

Concentration section

I clarified the information that was already in the Concentration section. Some of what is covered has nothing to do with concentration, such as the references to cyanidation, electrowinning, etc. But I left it in until a wider clarification of the whole article is made. Feel free to help out on this...BSMet94 03:55, 20 June 2007 (UTC)

And I got rid of the little hidden comment in there asking why the gold doesn't electroplate out too during electrorefining. Well, that's why it's called electrorefining. The solution conditions and electric potential across the cell are precisely controlled such that only copper (for instance) plates out on the cathode.BSMet94 04:04, 20 June 2007 (UTC)

Enectration?

In the section on extration from scrap electronics, the word "enectration" is used. I don't believe this is an actual word since the only search result is for this page. I would change it, but I'm not sure what is exactly meant by "enectration". CrinklyCrunk 14:50, 7 November 2007 (UTC)

I've never heard the word "enectration" before. Recovery of gold from electronic scrap has a lot of issues. First, there's the obvious materials handling problems. Circuit boards are difficult to move around my automated equipment, and shredding and separation are tricky. The resins present in the circuit board present a lot of emissions (chlorinated hydrocarbons, VOCs, etc.) problems if the recovery method is pyrometallurgical. There's a lot of other metals there too, particularly lead, tin, and copper, mostly in greater amounts than the gold. The gold recovered from e-scrap requires quite a bit of further separation and refining. Just some thoughts. I don't have time these days to edit Wikipedia articles. Hopefully things will slow down at work, and I'll get back to work on this fun stuff.BSMet94 20:41, 13 November 2007 (UTC)

Hopefully I too will have more time to edit. But for now, I was curious and found http://www.finishing.com/336/16.shtml while searching for ways to recover gold from e-scrap. Looks hard to to safely. 166.70.62.200 (talk) 22:23, 27 January 2008 (UTC)

I don't think it's hard to recover gold from e-scrap safely, just hard to do it economically AND safely.BSMet94 (talk) 20:24, 21 February 2008 (UTC)

I came to Wikipedia to read up on gold exraction from e-waste and was happy to find a section about it. There is a big market of gold scrap cpu, memory and connector edges on eBay. Several 'home kits' are also sold. And a lot of the waste dumped in third world countries are burned and refined to extract precious metals.

Types of ore

This article seemed to say almost nothing about what types of gold ore actually found, and which of the processes mentioned apply to which ores. I added a stub section about ores, which I'm hoping is roughly correct, but this needs expanding and it also needs tying in with the rest of the article. Presumably different processes are used for different ores? Anyway, I know almost nothing about this so I'll have to leave it to someone else! Matt 23:58, 8 January 2008 (UTC)