Secondary zinc with known impurities is loaded into the Swing Zinc Furnace where it dissolves.
SHG zinc offers the highest purity, doesn't require reprocessing, is convenient to work with, and can be used for production of all types of ZnO, but it comes at a higher cost. Some industries typically require SHG zinc as source material for production of zinc oxide:
- Electronics
- Pharmaceutical
- Cosmetics
Also known as Hard Zinc, Scrap Zinc, or Zinc Residues. Most available secondary zinc can be used by the BURNS process to produce high quality zinc oxide for the following industries:
- Tyres & Rubber (55% of ZnO market)
- Glass & Ceramics (20%)
- Chemicals (8%)
- Nutrition (7%)
- Paints & Coatings (3%)
Important secondary zinc buying tips!
1) Verify the amount of metallic zinc in the secondary material you are purchasing, to ensure that the discounted cost justifies the extra processing cost.
2) Total zinc numbers may be misleading as they may include zinc ash. Zinc ash cannot be converted into pure zinc by the BURNS process. Make sure the zinc numbers specify the quantity of metallic zinc.
3) High iron content materials are more expensive to process as they require more reagent and labor to purify.
4) High Lead content materials may be suitable feeds; however it is recommended that they be processed in the BURNS Retort Vaporizer designed specifically for this purpose. Typically, production rates will be 90% of the SHG zinc production rate due to the additional downtime for lead removal and recovery.
Secondary zinc with known impurities is loaded into the Swing Zinc Furnace where it dissolves.
Most impurities in the zinc react with the reagent to form a floating precipitate in the Swing Furnace.
The precipitate is removed from the Swing Furnace leaving 99.9% pure liquid zinc (from low Pb feed)
Precipitate is transferred to the Zinc Squeezer where any remaining metallic zinc is recovered and transferred back to the Swing Furnace.
Zinc with less than 0.06% iron is transferred to one of the BURNS vaporizing furnaces.
Remaining Contaminants: Although trace amounts of iron and other contaminants may reach the vaporizing furnace, their very high boiling points and very low partial pressures at the zinc boiling temperature ensure that their concentration in the product is of the order of ppb. See our Webinar for details.
Lead is not removed in the swing furnace and is handled at the vaporizing furnace by removal and liquation. Lead levels are easily managed in the 2-retort horizontal vaporizing furnace.