The metals I selected are from the RCRA 8 list and the 13 “metallic pollutants of concern” as well as gold.  Can’t evaluate metals recovery without thinking about gold!Source: 1996 Handbook of Chemistry and Physics Student Edition or listed websites when no information was in the Handbook.Pgs 8-60 to 8-62 and 5-4 to 5-23. A little background, the numbers I am giving are “Gibbs Free Energy” values at 25 C, 1 atm pressure which is considered “standard conditions”.  A larger negative value suggests that that specific compound will be more common under standard conditions (because more energy is released during formation versus being absorbed).The list of soluble metal salts doesn’t have many Gibbs Free Energy values because I suspect that either they are 1. too insignificant or 2. the values for GFE are only given for naturally occurring metal salts. All metals are provided with a list of the anions they combine with to form salts and the corresponding GFE values and notes of importance.   Robert, the CC’d email addresses are for Karen Frye, my CFO and Dr.Randall Tagg, my Science and Technology Consultant who is also the Chair of the CU Denver Physics Department. The list: Arsenic  Considered a heavy metal and fairly insoluble, but becomes much less toxic in waters with pH >8http://www.webelements.com/arsenic/compounds.html Antimony   Insoluble in waters above pH 7 when combined with the following anions: Arsenate AsO4, Arsenite AsO3, Oxide O3, Sulfate SO4, Sulfide S3.                          Antimony Sulfide is the most common form per environmentalchemistry.com/yogi/periodic/Sb.html Barium     Insoluble in waters above pH 7 when combined with the following anions:  Arsenate, Carbonate CO3, Chromate CrO4, Citrate (C6H5O7)2, Ferric (Fe(CN)6)2, Flouride F2 (-1156.8 – second most common form), Oxalate C2O4, Phosphate (PO4)2, Sulfate SO4 (-1362.2 – most common form), Tartrate C4H4O6. Cadmium   Insoluble in waters above pH 7 when combined with the following anions:  Arsenate, Carbonate, Chromate, Citrate, Ferric, Ferrous Fe(CN)6, Hydroxide (OH)2 (-897.5 – 4th most common), Oxalate C2O4, Oxide O (-603.3), Phosphate (-3884.7, most common by a value of 200%), Sulfide (-477.4), Tartrate. Beryllium   not evaluated for solubility, however magnesium is in the same group and should have similar properties               Magnesium  Insoluble in waters above pH 7 when combined with the following anions:  Arsenate, Carbonate, Flouride (BeF2, -979.4 second most common by 100 kJ/mol), Hydroxide, Oxalate , Oxide (-580.1, Phosphate, Silicate SO4 (-2055.1, lowest value by 100% meaning by far the most common), Tartrate Chromium   Insoluble in waters above pH 7 when combined with the following anions:  Bromide Br3, Chloride Cl3, Flouride (-1088.0), Oxide (Cr2O3) (-1058.1), Phosphate, Sulfate SO4, Ferrous Chromate FeCr2O4 (-1343.8).  These values are the three lowest and therefore the most common. Copper   Insoluble in waters above pH 7 when combined with the following anions:  Arsenate, Arsenite, Benzoate (C7H5O6), Cyanide, Ferric, Ferrous, Flouride F2, Hydroxide, Iodide (-69.5),

Oxalate, Oxide (-129.7 as CuO, third most common, -146.0 as Cu2O, second most common), Phosphate, Silicate, Sulfate, Sulfide (-53.6 as CuS, -86.2 as Cu2S), Tartrate  Lead   Insoluble in waters above pH 7 when combined with the following anions:  Arsenate, Benzoate, Carbonate, Chromate, Cyanide, Ferric, Ferrous, Flouride, Hydroxide, Oxalate, Oxide (-129.7 as CuO, third most common, -146.0, second most common), Phosphate, Silicate, Sulfate, Sulfide (-98.7, second most common), Tartrate, Thiocyanate Mercury I    Insoluble in waters above pH 7 when combined with the following anions:  Acetate (C2H3)2), Arsenate, Benzoate, Bromide, Chloride, Carbonate, Chromate, Citrate, Cyanide, Formate, Iodide (-101.7), Oxalate, Oxide (-58.5), Phosphate, Sulfate, Sulfide (-50.6), Tartrate,   Mercury II    Insoluble in waters above pH 7 when combined with the following anions:  Acetate, Arsenate, Benzoate, Chromate, Cyanide, Ferric, Ferrous, Flouride, Hydroxide, Iodide (-111.0), Oxalate, Oxide, Phosphate, Silicate, Sulfate (-625.8, lowest value by %600, by far the most common), Sulfide, Tartrate,  Nickel   Insoluble in waters above pH 7 when combined with the following anions:  Arsenate, Arsenite, Benzoate, Carbonate, Chromate, Cyanide, Ferric, Ferrous, Flouride, Hydroxide, Oxalate, Oxide, Iodide, Oxalate, Oxide, Phosphate, Sulfide (-79.5, second most common), Tartrate Selenium   The various forms of selenium behave differently in the environment. Heavy metal selenides, selenium sulphides, selenites, and selenates all vary in solubility (that is, their ability to dissolve in water). Selenates (salts containing one Se atom and four atoms of oxygen) are among the most mobile Se compounds due to their high solubility and inability to cling onto soil particles. Thus, they are readily taken up by microorganisms in the soil or leached through the soil. Selenites (salts containing one Se atom and three atoms of oxygen) are less soluble than selenates. Elemental Se is common in some soils, but does not dissolve much in water and therefore is not likely to be taken up by living organisms. http://www.ec.gc.ca/ceqg-rcqe/English/Html/GAAG_Selenium.cfm Zinc Selenide ( -163.0), Thallium (-59.0) only two compounds provided. Silver    Insoluble in waters above pH 7 when combined with the following anions:  Acetate, Arsenate, Arsenite, Benzoate, Bromide (-96.9), Carbonate, Chloride (-109.8), Chromate (-641.8 lowest value, most common), Citrate, Cyanide, Ferric, Ferrous, Iodide (-66.2), Oxalate, Oxide (-11.2), Oxalate, Oxide, Phosphate, Sulfate (-618.4  second most common), Sulfide (-40.7), Tartrate, Thiocyanate   Thallium  little solubility information  Selenium Thallide (-59.0) Gold I    Insoluble in waters above pH 7 when combined with the following anions:  Bromide (-53.3), Chloride (-117.6), Cyanide, Iodide, Oxide, Sulfide Gold II   Insoluble in waters above pH 7 when combined with the following anions:  Bromide, Chloride, Hydroxide, Iodide, Oxide, Sulfide