Copper cementation

[ajohnston]

Some geolgists have told me that cementation is not dead after all, and that there is a company commercializing a copper cementation process using iron prills.

Is this true? If so, please put me in touch. We need to squeeze a little more out of a tank house and she dont have the amps...

Adam

[barr]

Copper cementation is historical. It was the process that brought the (re) discovery of bioleaching, at Rio Tinto in the 18th century, when blue vitriol leachate was observed to cement onto iron tools. Forward to the future and Rio Tinto's Kennecott operation is still treating a copper seep of 0.1g Cu/L by cementation.

Kennecott developed cementation's state of the art when it replaced its launders with cones, all now dismantled and removed. However, Production wise, Kennecott cones are still being used (or have been very recently) in Australia, by Adelaide Chemical to cement Cu from oxide heap leach at Mt Gunson, S Australia, by Mt Leyshon in Queensland to demonstrate bacterial/CN heap leach for Cu/Au with Cu being cemented, and in 2005 there was discussion of using cementation in the treatment of historical ARD at Mt Leyell in Tasmania. These operations are the best places to check on the state of the cementation art.

Cementation certainly has low capital and low power requirements. It also has low PLS requirements. Which is where the question gets interesting. SX works best at ~3 g Cu/L. Kennecott demonstrated in a bioheap leach/SX/EW trial in the 1990's that maintaining 1g/L would still do. Next, ElectroMetals have built two demonstration plants using their EMEW cell ie direct EW with no SX, that is claimed to work at 0.5 g/L (this was also trialled on Freeport’s ARD). Further, Phelps Dodge have a JV with BioteQ where they have built a demonstration bio-precipitation plant in Arizona, working on 0.35 g/L (most of BioteQ’s other plants are to treat ARD). With bio-precipitation there are cost and complexity implications, but in terms of sustainability it means that recoverable Cu concentration is closing the gap between "PLS" and "ARD" and that has to be good, noting eg the Kennecott example above of cementation at 0.1 g/L. There is more than just amps at stake here.

Finally, an interesting thing to note re cementation is that Kennecott has been the major demonstration site for the US Mine Waste Technology Program's catalysed cementation, using zero valent iron (ZVI) to drop out contaminants such as As and Se. Applications elsewhere of ZVI for organic contaminants have looked at 100 nm scale particles. These are much more reactive and it could be speculated as to what difference this could make to Cu recovery, if it could be integrated into cementation, cost effectively. The twist is that 100 nm particles would make this a nanotechnology, and in the UK at least, there is a moratorium on deploying nanotechnologies. Implications of this definition to the use of ZVI in remediation (or possibly recovery) are as yet untested – unless someone can tell me otherwise?

[ngoviky]

With current sulphur prices going through the roof, we have received a number of inquiries from potential clients for roasting of pyrite concentrates to produce sulphuric acid. One of these concentrates comes from an existing copper concentrator.

We are investigating the possibility of leaching the copper in the calcine using the weak acid bleed from the acid plant and a small proportion of concentrated sulphuric acid.

We were then going to recover the copper by cementation using Kennecott cones (provided we can find a cheap and abundant source of scrap iron, which isn't all that obvious!!)

Now I have a few questions:
1) Is there a company that designs and fabricates these cones?
2) Are there used/decommissioned cones that could be purchased? (Mr.Google has not given me a satisfactory answer...)
3) Apart from cones, are there other types of equipment that would be suitable?

I welcome any insights and info you may have on the subject.

Regards,

Kim Ngoviky
Senior Process Engineer
Vector Engineering Inc.

[ravijain03]

EMEW can be an option to use against cementation process. The reason is EMEW has two types of electrolysers viz cathode and powder type. The powder electrolyzers work best for low copper tenure solutions. You can go to their website www.electrometals.com.au and check out online technical papers.

Regards,

Ravi Jain
EMEW