New Technology for Copper Removal from Lead by …
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Table 3 Chemical composition of Al–Cu drosses during the exemplary industrial test
Chemical composition of Al–Cu drosses (%)
Al
S
Cu
Sb
Pb
4.90
0.20
4.16
4.86
85.88
• The amount of the Cu drosses generated by the technology that uses sulfur is
approx. 2–3% of the lead mass,
• For the aluminum technology, the amount of by-products in case of Al–Cu dross
formation is 1.1, and 0.86% of lead mass for Al–Cu alloy production, that is
approx. 50% less by-products, therefore this technology is more efficient and also
more cost-effective.
The decoppering technology with sulfur causes the fact that the operation is often
repeated due to the oxidation of sulfur during batching. Each additional decoppering
with sulfur causes the formation of additional amount of Cu drosses that increase
the lead losses. The technology that uses aluminum eliminates this problem because
after a single batching of aluminum, low copper content (below 5 ppm) as well as a
constant amount of generated by-products is guaranteed.
Due to the utilization of the final temperature of the previous operation (lead oxidation), no additional heating of the refining kettle is required to process aluminum.
Therefore, the energy efficiency increases.
Practical Problems of Lead Decoppering
with the Application of Aluminum
The lead decoppering technology with the application of aluminum has been functioning in the industry since 2011, without any significant issues. This technology
has been constantly improved and was easily incorporated into lead refining process.
In 2016, after 5 years of utilization of this technology, a problem of ignition of Al–Cu
drosses, which were a huge problem due to the safety standards, was reported. The
incandescent Al–Cu drosses in the refining kettle are presented in Fig. 4.
Both laboratory and industrial scale tests have been performed in order to eliminate this problem. The factors that could cause these problems were analyzed. The
Al–Cu drosses have a powdery form and contain fine metallic particles. The reaction between aluminum and oxygen is a strong exothermic reaction. The very fine
particles are characterized with a large specific surface area; therefore, the oxidation proceeds rapidly and generates a large amount of heat that can be manifested
with incandescence or even explosions. The additional factor that may influence the
ignition of drosses is the application of aluminum scrap, that contains flammable
components, i.e. magnesium and sulfur, which have a greater affinity to oxygen than
aluminum, and the reaction is even more rapid and generates larger amounts of heat.
Another factor which may initiate the ignition of drosses is the substance used to dry
733
Table 3 Chemical composition of Al–Cu drosses during the exemplary industrial test
Chemical composition of Al–Cu drosses (%)
Al
S
Cu
Sb
Pb
4.90
0.20
4.16
4.86
85.88
• The amount of the Cu drosses generated by the technology that uses sulfur is
approx. 2–3% of the lead mass,
• For the aluminum technology, the amount of by-products in case of Al–Cu dross
formation is 1.1, and 0.86% of lead mass for Al–Cu alloy production, that is
approx. 50% less by-products, therefore this technology is more efficient and also
more cost-effective.
The decoppering technology with sulfur causes the fact that the operation is often
repeated due to the oxidation of sulfur during batching. Each additional decoppering
with sulfur causes the formation of additional amount of Cu drosses that increase
the lead losses. The technology that uses aluminum eliminates this problem because
after a single batching of aluminum, low copper content (below 5 ppm) as well as a
constant amount of generated by-products is guaranteed.
Due to the utilization of the final temperature of the previous operation (lead oxidation), no additional heating of the refining kettle is required to process aluminum.
Therefore, the energy efficiency increases.
Practical Problems of Lead Decoppering
with the Application of Aluminum
The lead decoppering technology with the application of aluminum has been functioning in the industry since 2011, without any significant issues. This technology
has been constantly improved and was easily incorporated into lead refining process.
In 2016, after 5 years of utilization of this technology, a problem of ignition of Al–Cu
drosses, which were a huge problem due to the safety standards, was reported. The
incandescent Al–Cu drosses in the refining kettle are presented in Fig. 4.
Both laboratory and industrial scale tests have been performed in order to eliminate this problem. The factors that could cause these problems were analyzed. The
Al–Cu drosses have a powdery form and contain fine metallic particles. The reaction between aluminum and oxygen is a strong exothermic reaction. The very fine
particles are characterized with a large specific surface area; therefore, the oxidation proceeds rapidly and generates a large amount of heat that can be manifested
with incandescence or even explosions. The additional factor that may influence the
ignition of drosses is the application of aluminum scrap, that contains flammable
components, i.e. magnesium and sulfur, which have a greater affinity to oxygen than
aluminum, and the reaction is even more rapid and generates larger amounts of heat.
Another factor which may initiate the ignition of drosses is the substance used to dry