The current processes in copper pyrometallurgy are partially operated with fuels and reducing agents based on fossil sources producing climate-relevant emissions such as CO2. Nut coke represents the main energy carrier and reducing agent within the classical shaft furnace process. The coke is charged via the furnace top, whereas a uniform distribution for the reduction processes is not always guaranteed inducing a certain amount of time, until charging adaptions have an impact on the furnace process. Therefore, a precise process control is hardly to realize. The injection of reactive and reducing gases via lances can control the metallurgical reactions immediately; however, the corresponding reducing reactions during the secondary copper refining process are not completely clear yet.

The processing of complex fine-grained materials is still challenging, since not all kinds of fine-grained materials can be agglomerated efficiently for a subsequent use in the shaft furnace. Furthermore, agglomeration induces high costs. The injection of complex secondary copper materials as an alternative to the rather expensive agglomeration is therefore attractive. However, the behavior of these secondary raw materials during pneumatic conveying as well as the accompanied metallurgical reactions are not completely known yet.

Recycling materials containing Nickel, Zinc, Lead, Tin, Copper, Bismuth and other elements complicate the metallurgical raffination and require process adaptions, on the one hand to guarantee certain product qualities and on the other hand, to reach a certain output of valuable materials. Complex materials cause problems in the standard shaft furnace process and can therefore not be recovered. In addition to this, increased energy demand and subsequently the CO2 emission are a consequence of the complex material mix. To reach the climate goals, utilization of hydrogen as reducing agents and the use of feed components with reducing properties are necessary.



Objectives and Motivation

  • Partial coke substitution during the copper refining process via injection of alternative gaseous reducing agents
  • Raffination methods for complex copper secondary raw materials for the separation of impurities
  • Reduced loss of valuable materials in the process slag


Profound literature studies and accompanied thermodynamic calculations represent the basis of the planned methodology. Regarding injection of gaseous reducing agents and fine-grained materials during copper shaft furnace pyrometallurgy, state-of-the-art as well as the knowledge from other research group represent the basis to further develop the raffination process at the site of our industrial project partner. The results from the thermodynamic calculations should reveal the expected reaction equilibria and kinetics.

Bases on the theoretical knowledge gained during the project, experimental trials and campaigns are planned in lab-scale and at the real shaft furnace plant. These tests should evaluate the feasibility of the developed concepts and the thermodynamic calculations respectively. During the experiments, off-gas analysis (CO, CO2, CH4, O2, NOX, H2) should be done.

Results and application

At the end of the project, adaptions of existing lance systems for the injection of alternative reducing agent such as hydrogen should be suggested, and the optimum operating parameters should be defined respectively. Regarding the raffination of copper containing secondary raw materials and circulating materials, suitable recipes of fine-grained materials as well as an industrially applicable injection system should be provided at the end of the project. Based on the obtained results, comprehensive knowledge is expected regarding the composition of the product phases as well as the element distribution (valuable metals) within these phases. This information should be used to evaluate the further product utilization.