Optimizing your copper making process

The demand for copper grows continuously. Thanks to sectors such as electronic products, industrial machinery, transportation equipment, etc. the refined usage of copper has more than tripled in the last 50 years.
To tackle the challenges of the customer, Heraeus Electro-Nite offers some unique solutions specific for the different copper process steps.

The refined copper production can be divided into two main production routes, primary and secondary copper production. Approximately 80% of that refined copper production is primary copper production, where copper is derived from ores.
The other important source of raw material is scrap. Copper scrap, derived from either metals discarded in manufacturing processes or end of life products, contributes to recycling of copper as raw material. This route is the secondary copper production.

Find out which solutions are applicable for your process and how they can help you to optimize your copper process.

Copper production

Copper production begins with the extraction of copper ores through surface (open-pit) or underground mining. Depending on the amount of copper scrap added to the process, the production can be classified as primary or secondary production.

Products:

Two main process routes are followed:

  • A hydro-metallurgical route or SX-EW process, where copper is directly extracted and refined from low grade ores
  • A pyro-metallurgical route where copper is extracted and refined from ores, copper scrap and/or spent anodes

In the pyro-metallurgical process route, raw mined ore is first upgraded to copper concentrate by means of crushing and flotation enrichment processes. This concentrate is subsequently melted and transformed into ‘matte’ containing around 60% pure copper. The liquid ‘matte’ is refined in a converter process where ‘blister’ copper is produced with > 98% copper content. Blister copper is then casted into intermediary anodes which are further refined into copper cathodes (99.99% pure copper) through an electro-refining process. Cathodes are re-melted and processed into final end user products. Blister copper feed can be partially or fully replaced by secondary scrap to recycle end of life copper.

Main challenges of the pyro-metallurgical process

Manage oxygen activity during refining

In the convertor blister copper and/or copper scrap are melted and oxidised at a temperature of around 1150-1250 °C. Ideal refining conditions are reached close to the oxygen saturation point. Substandard oxygen input results in insufficient refining and unacceptable high impurity levels. Excessive oxygen input increases significantly process yield losses.

After the refining treatment the oxygen content of the liquid copper has to be reduced enough to allow casting of 99% pure anodes. This is done by injecting natural gas in a poling furnace.

Using the Heraeus Electro-Nite’s oxygen activity control allows the customer to manage his process by:

  • Optimizing oxygen injection
  • Fine tuning natural gas injection

Oxygen control during copper rod casting

More than half of the worldwide copper demand is for cast and rolled copper wire rod, and used as the starting product for the electrical and electronics industry. World standard are the CONTIROD and HAZELETT concaster systems where copper rod is continuously cast, then shaped to wire. To ensure the overall end product quality, the copper's oxygen content must be controlled at individual steps, at certain check points along the continuous process line. The oxygen content of copper is decisive for internal and external quality of the as-cast rod and as-rolled wire.

Where both, access to the liquid metal is difficult but sufficient immersion depth are given, such as in furnaces and ladles, the Heraeus Electro-Nite's disposable Celox-Cu sensor measures the oxygen content instantly within seconds. Where channnels and launders guide the liquid copper on its way to the crystallizing mould, our continuous oxygen sensor Concelox-Cu may favorably be applied. Concelox-Cu gives an online continuous oxygen measurement. Both sensors, Celox-Cu and Concelox-Cu cover with their precise oxygen measurement the full range of technically prevailing oxygen content in copper, starting from 0 up to 12.000ppm.

Customer benefits from sensor use are almost self-explainable. Whereas a copper sample takes at least 15 minutes to return the analysis result from lab to process line, the Heraeus oxygen sensors do the job either in seconds or continuously thus leaving line operators a much quicker decision to react (to intensify oxydation,or downpole oxygen) when oxygen is getting out of the tolerable oxygen specification. A much tighter oxgen range is thus matchable in the as cast, as -rolled product what is self-evident from the above said control speed. In terms of cost comparison for lab sample and sensor, the disposable sensor meets cost for sample taking and analysis. The continuous Concelox-Cu sensor with its service life of about 1 week beats the comparable cost for lab samples and analysis by far, sensor cost is just 15% of those for samples, as a continuous CONTIROD or Hazelett line would require at least 6 samples per day, minimum 2 samples per shift. In total: Celox-Cu operates cost neutral, Concelox much cheaper compared to sampling/analysis practice of the past. In addition, the amount of savings due to a better quality yield from better process control depend on each and every individual line condition; longer term in-plant statistics will prove.

Needless to say as well, that sensor application eliminates the hazardous sampling practice.