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

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Sheet, 7% Die Casting, 17% Miscellaneous, 4% Chemicals, 7% Brass, 18% Galvanizing, 47% FIGURE 1: End-Use Zinc Consumption Distribution [Ref. 1] Over the past fifty years the production of metallic zinc has increased by over three times [Ref. 2] with consumption levels now exceeding 7 million tonnes annually [Ref. 3]. However, due to this increasing demand as well as numerous other economic issues, the production supply of primary zinc has been unable to keep pace with required zinc tonnage. As shown in Figure 2, the demand for primary zinc has steadily grown over the past five years, but the zinc supply has been both erratic and diminishing. In addition it is widely accepted that this deficit in zinc production will not subside until mid-2007 or beyond [Refs. 1, 3-6]. At present the scarcity of zinc is making many zinc consumers invest in secured zinc supply just to avoid a potential interruption in raw material. Western Market Zinc Supply and Demand (Mt/yr) 8.0 7.5 7.0 6.5 6.0 5.5 5.0 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Demand Supply FIGURE 2: Zinc Supply and Demand Trends with Projections for 2007 [Ref. 3]
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
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The advantages of recycling metallic zinc from the ... - Pyrotek

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