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Gold/Mining/Energy : Global Platinum & Gold (GPGI) -- Ignore unavailable to you. Want to Upgrade?

To: JACK R. SMITH JR. who wrote (6417)	6/26/1998 11:02:00 PM
From: Zeev Hed	Read Replies (2) \| Respond to of 14226

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

To: JACK R. SMITH JR. who wrote (6417)	6/27/1998 1:10:00 AM
From: Carlton E. Wheeler	Read Replies (3) \| Respond to of 14226

Jack, The following is some general information about exchange resins which while it may be years out of date, will help you and others understand what they are and how they are used. The resins are synthetic polymers which have the ability to exchange ions which are chemically bonded to them for other ions which are either more strongly attracted or are in such concentration in the solution to which they are exposed that the original ion is displaced. There are both cation exchange resins and anion exchange resins. Since all metal ions are cations, the resins in this case are cation exchange resins. The resins are fabricated to a close size fraction either by crushing the solid polymer and screening to separate a closely sized portion or by producing them as beads of uniform size, usually about like coarse sand. In use the resins are contained in columns which can be from inches to feet in diameter. The column is constructed so that the solutions added to them will flow through uniformly without channeling. Resins of the same type are used in water softeners. Some water softeners have salt tanks where the home owner places salt to make a salt solution. The salt solution is passed through the resin column and charges it with sodium ions. When hard water is subsequently passed through the column, the Na ions are replaced by the Ca and Mg ions which are the culprits that cause soap scum and the effluent water contains only Na ions which do not cause soap scum and is thus "softened". Others use resin tanks which are recharged elsewhere and are changed by the supplier such as Culligan. In the case of metal recovery, the resin column is charged with Hydrogen ions by passing a solution of acid through the tank, usually HCl or H2SO4. When the metal containing solution is passed though the column, the H ions are displaced and the metal ions are retained. Conductivity measurements of the effluent indicates when the column is exhausted of H ions and can hold no more metal ions. The concentration of the metal ions in the solution does not have much to do with the amount of metal that is retained on the column. If it is dilute, a lot will pass through before the H ions are used up. It it is more concentrated, less solution will be required to "fill" the column with metal ions. While it is unlikely that the resin columns would be used to separate the metal ions from each other it is possible to obtain very complete separation due to the fact that each different metal, be it Au, Pt, Rd, Os, Ag, Rb, Cu or whatever, will be "held" by the resin to a different degree. If a solution containing a mixture of different metals ions, say a mixture of metal chlorides and nitrates, is poured onto the column to establish a metal ion containing zone at the top of the column and then a dilute acid solution is added to the column with the liquid level controlled so that it stays constant, the different metal ions will appear in the effluent at different times, the less tightly held first and the most tightly held last with each of the others appearing according to how tightly they are held by the resin. (Using some non-chemical terminology). This phenomenon was used about 55 years ago during the Manhattan project to separate isotopes of uranium. There was sufficient difference in the attraction to the resin between U235 and U238 to make the separation possible. Another use of exchange resins is to make de-ionized water. In this case the cation column is charged with acid to place on it Hydrogen ions and the anion column is charged with a hydroxide such as NaOH, KOH, or NH4OH to charge it with OH ions. When water containing dissolved substances is passed through first one column and then the other, the unwanted cations (Ca, Mg, etc.)are replaced by H ions and in the anion column the CO3 and Cl, etc are replaced by OH ions and the result is pure water. Huge amounts are produced for chemical processing, drug production and even in electrical discharge machining which must take place in a non conductive bath. (Very pure water does not conduct electricity easily. Its resistivity approaches 600,000 ohms/sq cm). Carl Wheeler