Michael J. Strelbisky, General Manager, A.H. Tallman Bronze Co. Ltd.
The A.H. Tallman Bronze Company Limited has been conducting extensive research
and development work into improving the service life of copper lance tips.
The new design permits incremental increases in the number of heats achieved
per lance tip without altering other operating parameters. Trials indicate
that the design improvements in the lance tips have beneficial effects on
furnace operating conditions.
The development work has achieved two of the most desirable results. Part one
involved improving the cast structure of the lance tip. Part two involved
optimising the heat transfer between the cooling water and the interior
face of the lance tip.
LANCE TIP STRUCTURE
Copper lance tips using a process proprietary to A.H. Tallman Bronze Company
Limited are cast using a centrifugal casting method. A newly developed grain
refinement process allows Tallman Bronze to selectively refine the grain size
of the copper in critical contact areas. The bottom of the lance tip (fig. 1.)
shows the typical grain size of a cast lance tip.
The same view of a lance tip
cast in the new process (fig. 2.) shows a change in the grain size.
grain size is significantly reduced. This macrograph shows the product of the
newly developed grain refinement process. Reducing the grain size improves
the erosion resistance of the copper and thus contributes to improved lance
The patented lance tip design builds on all existing knowledge of lance tip
cooling and erosion. Figure 3. shows the heat transfer along the inside
bottom face of a typical four (4) hole lance tip. Note the areas of low
heat transfer. These areas are directly opposite the areas where high
erosion usually occurs. Figure 4. is a graphic representation of heat
transfer in a new design lance tip and is evidence of significant
improvement in the heat transfer properties along the entire inside
bottom face of the lance tip. A modification in the geometry of the
internal water passages results in the improvement in the heat
transfer properties. Improved heat transfer increases the erosion
resistance of the lance tip and reduces the softening tendency of
copper. Corresponding increases in the strength of the lance tip
are also expected. The combination of refined grain structure and
improved heat transfer will lead to improved lance tip efficiency
and lance tip life.