COPPER SLAG

For around 800 years, a polymineral ore has been mined at a depth of up to 1000 m and a seam thickness of between 35 and 40 cm in the Mansfeld region, which is one of the oldest copper slate mines in the world.

With a copper content of between 0.23 and 2.9 %, the copper was distributed in the form of sulphide ore minerals in the microscopic area with the surrounding rock in varying degrees.

This meant that processing the ore using conventional flotation processes was completely out of the question. The extraction of copper and all metals contained in the ore could only be achieved metallurgically, in the shaft furnace process of the copper smelter using coke as a reducing agent and a considerable amount of energy. After being blown in the Bessemer converter with a copper content of approx. 96 %, the raw stone produced in this process with a copper content of approx. 40 % was further processed in the Mansfeld process (copper refining in the flame furnace and subsequent use in copper electrolysis) into saleable copper with a purity of 99.95 % Cu.

The metallurgical process was associated with the production of enormous quantities of copper slag, which was stockpiled in liquid form in the immediate vicinity of the smelters. Small quantities were used for the production of road construction and dyke construction formats

In the vicinity of the three largest smelters, Eckardt-Hütte Vatterode, Karl-Liebknecht-Hütte Eisleben and August-Bebel-Hütte Helbra, the amount of copper slag stockpiled is estimated at around 66 million tons.

Their chemical composition and presumably also their mechanical properties differ due to the different smelting technologies over time and should be evaluated accordingly.

The planned projects for investigating the possible uses and utilization of the mineral raw material Mansfeld copper slag are defined as a key task of the RBFK on the basis of comparable tests and processes researched worldwide.

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