Jack, until the expert give us an answer to your question, I'll attempt one in a much less than perfect English.
When they dissolve the goodies from the ore the solution is very dilute in the goodies and very rich in garbage. Some of that garbage is hopefully left in the solution after precipitation of the goodies, but a lot of garbage is in the precipitate as well (after all we have about 18 to 30 lbs of the precipitates and these contain only 65 grams of goodies per ton). So now we smelt it, the garbage goes as oxides into the slag while the goodies dissolve in the copper. Than the copper is dissolved again and that is "resinated". If you assume a ratio of 30 to 1 for the solution relative to its solids' content, if you used the leaching solution from the ore, you would have to treat on resins about 30,000 liters per ton of ore, but when you go through the smelting process, you have to treat only about 500 liters of solution per tons (these numbers are arbitrary, but the ratio between the two is more or less right).
Furthermore, the original leaching solution probably contains a bunch of ions (iron, calcium, magnesium, etc.) which could easily poison the resin, the smelting process removes these in the form of oxides in the slag.
I hope that explains more or less the rationale.
Zeev |
