The advantages of recycling metallic zinc from the ... - Pyrotek

Consequently, the negative impact that has developed as a result of the depleted zinc production
has been a sharp rise in primary zinc prices. Over a twelve month period from May 2005 to May
2006 (Figure 3), zinc prices rose at an unprecedented pace from US$0.565/lb. to US$1.625/lb.
In addition, these LME cash prices did not reflect surcharges, delivery fees and other “extras”
imposed by the zinc producers.
LME Cash Price (US$/Tonne)
$4,000
$3,500
$3,000
$2,500
$2,000
$1,500
$1,000
$500
$0
January-05
March-05
May-05
July-05
September-05
November-05
FIGURE 3: LME Cash Price for Zinc and Hot-Dipped Galvanized Steel (HDG) [Ref. 7 & 8]
Meanwhile, as the costs of zinc were rising rapidly, galvanized steel producers tried to maintain
analogous price increases for the finished hot-dip galvanized sheet steel (Figure 3), however, the
cost differential still impacted the bottom line for many producers. “Zinc is now reported to
account for 25% to 30% of the cost of HDG steel, as compared to around 5% before the price of
zinc headed skywards [Ref. 5].” Hence, steel companies must now start to consider alternative
technologies for minimizing their zinc consumption such as tighter coating weight control and
recycling of metallic zinc waste materials.
January-06
March-06
Zinc Recycling
Zinc, like most other metals, is easily recycled and approximately 30% of the overall zinc
consumption is currently from secondary sources [Ref. 2]. Many zinc-based products can
reintroduce scrap components back into the production process with little variation. Brass scrap
and zinc die castings can be directly remelted and recast as new parts much in the same manner
as aluminum and iron castings. However, zinc-coated steel scrap and galvanizing process wastes
are not as readily returned to the manufacturing process flow. In 1996, it was reported [Ref. 2]
that the utilization of secondary zinc ingot by galvanizing facilities equated to less than 40% of
the tonnage of the zinc scrap, drosses, residues and wastes produced by the coating process.
May-06
July-06
September-06
Zinc
HDG