ZnO for most applications

Burns Energy Systems equipment can produce White grade zinc oxide suitable for just about any industry, using preprocessed secondary zinc. ZnO average purity is 99.8% from top-dross. About 93% of the ZnO market can be supplied with White grade zinc oxide. Platinum and Gold grades are possible. See our Webinar for details.

Special High Grade Zinc (SHG)

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  

Secondary Zinc

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%)

Secondary Zinc Sources

Although there are various types of secondary zinc available on the market, some are easier to process than others. Check the "Financial Case" page to see which source material would be most suitable and profitable in your particular situation. 

  • Top Dross - One of the best sources of secondary zinc due to its typically low lead and consistent iron levels.  Top dross can be as high as 98% zinc, and is usually uniformly shaped making handling and assay testing easier. BURNS furnace equipment is designed to process large irregular blocks.
  • Die Caster Dross - Typically a good quality source of secondary dross generated from Aluminum and Zinc operations. Zinc content is usually lower, but some alloy additions are beneficial for the process.  
  • Bottom Dross - Although it can be processed, it tends to be a poor source of secondary zinc due to its varying quality. Bottom dross can contain solid iron and high quantities of lead. It is often supplied as irregular shapes making it difficult to handle. High iron levels require greater quantities of reagent metal increasing processing costs and lowering yields.
  • Zinc Blow-off Fines - Very poor source of zinc due to its potentially high contamination and its usually low metallic zinc content. Fines have a high surface area making them more prone to oxidation during melting. Look at subducted immersion technology for a better method of preprocessing. 
  • Zinc Ash & Skimmings  - Not recommended. Very low metallic zinc content. Already oxidized zinc will not yield metallic zinc in this process.

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 Processing

BURNS process for removal of Fe, Ni, Al, Cu, Ti, Sn, etc. from Secondary Zinc

Using secondary hard zinc to produce zinc oxide ZnO

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.

  • The BURNS process can be operated as a continuous process 
  • Can deliver high quality zinc to the vaporizer even when not all the zinc is dissolved
  • Provides a very compelling financial case for switching to secondary zinc feed 

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.


A. H. Burns Energy Systems Ltd.
1-1370 Sandhill Drive,
Ancaster, ON, Canada  L9G 4V5


Email:           Phone:  905.525.6321