
214 Aluminum Recycling
Figures 12.6 through 12.8, from the results of Hopkins et al. (1995), show the
results achievable in a casting furnace using a rotary gas injection pump. Figure 12.6
shows the hydrogen content of molten aluminum (~2.5% Mg) under different ren-
ing conditions. As previously mentioned, the use of chlorine in the purge gas makes
no difference in the reduction of hydrogen content. Figure 12.7 shows the inclusion
content of the melt as a function of time; here, the impact of adding 5% Cl
2
to the
gas is obvious. Figure 12.8 shows the reduction of alkali content achievable when
0.5
0.4
0.3
0.2
0.1
0
0
60 120
Hydrogen content (cc/100g ...