Iron-zinc separation

Iron-zinc separation fix)m solutions has always presented a challenge to the hydrometallurgist, b industrial practice, iron and zinc are separated by selective precipitation of an iron (III) precipitate from zinc. Various processes are or have been practised commercially depending on the form of the final iron precipitate (jarosite, goethite, para-goethite and hematite). Apart fix)m the inherent difficulties of each of these processes, iron is lost in those systems it cannot be recycled and therefore becomes a consumable, and this is likely cost prohibitive in the process considered here. 

The challenge for the hydrometalliugist resides now in effecting a x)d iron-zinc separation from the leach solution. Several solvent extraction options appear feasible but need to be demonstrated and integrated within the global process. 

The acidity of the aqueous strip solution is a very strong variable whose value should be carefully selected in order to effect a compromise among the iron removal, the zinc concentration in the iron product, the stoichiometry of the process, the process rate and the iron-zinc separation index. As demonstrated, it is possible to separate iron from zinc sulfate electrolyte and recover a concentrated, potentially usable form of iron. It is interesting to contemplate the use of galvanic stripping for the removal of other less concentrated impurities or valuable by-products from zinc processing solutions or from other hydrometallurgical streams, eith in conjunction with iron removal or separately. 

Iron titanates, 25 46 47 Iron titanium brown spinel, formula and DCMA number, 7 348t Iron trimer, 16 62 Ironworks, early American, 14 492 Iron/Zinc/Magnesium Oxide Tan pigment for plastics, 7 369t Irradiated uranium, plutonium separation and purification from, 19 674-675 Irradiation... 

A major zinc ore is ZnS (sphalerite) which frequently occurs with the major lead ore PbS (galena). The lead-zinc ores usually contain recoverable quantities of copper, silver, antimony, and bismnth as well, Major deposits of Ihis type are worked in Australia, the United States, Canada, Mexico, Peru, the former Yugoslav Republics, and the former Soviet Union. Two other important zinc ores are ZnCC>3 (smithsonite) and iron-zinc-manganese oxide (franklinite). Several of these minerals are described under separate alphabetical entries. 

H2 ANTAGONISTS COPPER AND IRON 1 plasma and body concentrations of copper, iron, zinc and calcium As a class, H2 antagonists act as free radical scavengers and cause depletion of calcium, iron and zinc. Cimetidine in particular binds to copper and iron, and these minerals are not made available for free radical production Be aware and separate oral intake by 2 hours... 

CIPROFLOXACIN MINERALS-CALCIUM, MAGNESIUM, IRON, ZINC, COPPER 4 plasma/body levels of calcium, magnesium, iron and zinc 4 absorption due to formation of unabsorbable chelates Separate oral intake by at least 2 hours... 

Salts.—The salts of succinic acid are not of especial importance The basic ferric succinate is used in the analytical separation of iron, zinc, manganese, cobalt and nickel. As stated above when succinic, acid is heated rapidly to 235° it loses water and forms an anhydride. 

Detection and Estimation. — Beryllium is detected in qualitative analysis by the reactions which distinguish it from aluminium, zinc, and iron. (See Separation.)... 

Iron or zinc separate the element from solutions of its salts. 

The most economically important zinc mineral is the zinc blende (ZnS). Zinc blendes are contaminated by iron, and separating this contaminant is considered as the central metallurgical problem. Usually, pure zinc is produced by the following technical... 

Analytical Characters.—(1.) Hydrogen sulfid, in acid solution a black ppt. insoluble in alkaline sulfids, and in cold, dilute acids. (2.) Ammonium sulfhydrate black ppt. insoluble in excess. (3.) Hydrochloric acid white ppt. in not too dilute solution soluble in boiling HaO. (4.) Aiumoniuiu hy-droxid white ppt. insoluble in excess. (5.) Potash white ppt. soluble in excess, especially when heated. (6.) Sulfuric acid white ppt. insoluble in weak acids, soluble in solution of ammonium tartrate. (7.) Potassium iodid yellow ppt. sparingly soluble in boiling HaO soluble in large excess. (8.) Potassium chromate yellow ppt. soluble in KHO solution. (9.) Iron or zinc separate the element from solution of its salts. 

The interesting combination of capillary electrophoresis-X-ray fluorescence detection was recently described as an element-specific detector [136]. A special plastic cell, which was both X-ray transparent and did not produce any interfering emission, was used. Vitamin B-12 (cyanocobalamin) and the cyclohexanediaminotetraacetic acid complexes of iron, zinc, cobalt, and copper were separated. Although the detection limits found were in the nanogram range, the authors estimate that with optimization that 2 or 3 orders of magnitude more sensitivity is likely. 

On the other hand, in the case of zinc coatings on iron, zinc usually is anodic with respect to the substrate. If the corrosion products are the result of the interaction between the anodic and the cathodic products, as the anodic area (zinc) and cathodic area (iron) are separated, the corrosion products are formed within the solution and do not hinder the electrode processes. This is the case, for example, in the formation of zinc hydrate in aerated solutions of sodium chloride. The cathodic process that occurs on the iron supports the anodic dissolution of zinc and lead quickly to the increase in the size of the defects. If the corrosion problem was the rate of penetration into the substrate, the coating would be safe but of short duration. 

---