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New ecological technology to remove copper from lead with the application of aluminium and its alloys.

Country of Origin: Poland
Reference Number: TOPL20171130001
Publication Date: 6 December 2017

Summary

A Polish research institute has developed a new ecological technology to remove copper from lead, which is the alternative for the sulfur method which is currently used in the non-ferrous metallurgy. Other technologies incorporating sulfur for lead decoppering have several disadvantages that can be eliminated by this new technology. 
The institute is looking for partners who are interested in  cooperation based on licence agreement or commercial agreement with technical assistance.

Description

The Research Institute in Poland conducting research in the field of: minerals treatment and waste utilization, metallurgy, hydrometallurgy, material science, electrochemical power sources and more.

Lead decoppering with the application of sulphur is a commonly known process used worldwide, however it does not necessarily successfully remove copper due to the oxidation of the part of sulphur. Often, the process needs to be repeated, what increases the costs, the amount of byproducts, lead losses and prolongs the operation time. Application of sulphur for lead decoppering and melting the Cu drosses has the negative influence on the netural environment due to the SO2 emission to the atmosphere.

The new lead decoppering process which involves the application of aluminium is based on the formation of copper and aluminium intermetallic compounds. With decreasing temperature those compounds form the Al-Cu foam (containing 5-10% Cu), which can be collected in the metallic form or it can be dried to powdery Al-Cu drosses. By introducing aluminium to lead in the form of Al-Zn alloy we can decrease the initial process temperature. Other option is to melt aluminium on the lead surface and slowly stirr. The liquid Al phase formed on the lead surface absorbs Cu from lead as a result of the decreasing solubility of this compound with decreasing temperature.

Liquid alloy freezes at the eutectic point and can be collected from the lead Surface. The microstructure pictures of the Al-Cu drosses show that the intermetallic compounds which are formed are mostly the compounds with higher copper proportion, i.e. Al2Cu3, and for Al-Cu alloy it’s mostly Al2Cu.

The experimental results also confirm that aluminum cleans lead from other contaminants, i.e. Sb, As or Ni. The developed technology provides the copper reduction from lead to the concentration lower than 5 ppm. It is preferable to use the decoppering technology directly after lead oxidation and to use the high temperature on the end of that process in order to provide the higher energy efficiency of the technology.

Lead decoppering technology with the application of aluminum and its alloys can be characterized with:
- Elimination of sulfur compounds from the formed byproducts,
- Small amount of the byproducts:
• 1,1% lead mass for Al-Cu drosses,
• 0,86% lead mass for Al-Cu alloy.
- Repeatability of the results,
- Guarantees copper reduction to the concentration lower than 5 ppm for each case,
- Removes other contaminants such as Sb, As and Ni,
- Easy to implement,
- Less labor-intensive process,
- Increased operational safety.

The institute is searching a partners, mainly industrial companies operating in the field of non-ferrous industry who are interested in implementation of the presented technology in the industrial conditions in the plants involved in the production of refined lead or lead alloys (licence agreement or commercial agreement with technical assistance).
Institute offers the possibility to test the material processing in laboratory and pilot scale as well as to implement this technology in the industry.

Advantages and Innovations

The new lead decoppering technology with the application of aluminum leads to the complete elimination of sulfur compounds from the generated byproducts, making it an ecological technology.

Comparing the amounds of generated byproducts:
- the technology that uses sulfur, the amount of produced Cu drosses is approx. 2-3% lead mass per batch,
- the amount of the generated byproducts is 1,1% for Al-Cu dross, and 0,86% lead mass for Al-Cu alloy. The amount of generated byproducts is approximately 50% lower - the technology is more effective and economical.

During lead decoppering with sulfur, the part of the sulfur is partially oxidized during feeding to the furnace, and therefore the operation often needs to be repeated. Each additional decoppering with sulfur leads to the formation of the additional amount of Cu drosses and thus the lead losses increase. The technology that uses aluminum eliminates this problem because each single batching guarantees low copper content less than 5 ppm and constant amount of formed byproducts.

Utilization of the high temperature of the end of the previous process (lead oxidation) is favorable since no additional heating is required and therefore the technology is more energy efficient. Easy implementation of the technology is also associated with the lower labor consumption. The new technology is based on melting the aluminum into lead and then cooling it to the low temperature.

In case of the technology that uses sulfur, the employee is involved throughout the whole operation because this technology requires constant dosing of small portions of sulfur due to the sulfur flammability. This is also the reason why this technology is less safe. In case of the aluminum technology, the employee only needs to feed the aluminum in one portion and mix it with the mechanical mixer. The next stage, where lead is cooled, requires only temperature control at the end of the process, so that the employee can perform other tasks.

Stage Of Development

Already on the market

Requested partner

The potential partners coluld be any industrial enterprises active in the field of non-ferrous industry interested in a licence agreement or commercial agreement with technical assistance so as to use the new method for the decoppering technology with the application of aluminium during refining of lead both from primary and secondary sources. Any partner interested in cooperation can count on the possibility of testing the material processing in laboratory and pilot scale as well on Institute support in technology implementation.

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