Copper is widely used not only in electronic devices, but also for water lines, electrical circuits and transport systems. Chile is the most important copper ore producing country but also in Europe copper ore is extracted in Russia, Poland, Portugal, and Sweden. However, Germany possesses also significant copper ore deposits. In the Mansfelder Land, coppershale (Kupferschiefer, see information box for further information) was mined until 1990, and many waste dumps remind of its mining history of this region. Other areas with significant Kupferschiefer deposits are the region of Spremberg and the region of Weißwasser, Lausitz.
Kupferschiefer is a calciferous, carbon rich marly clay with finely dispersed sulfidic copper minerals, mainly chalcocite, bornite, and chalcopyrite. The ores also contain up to 20 other metallic and metalloid elements. Further, Kupferschiefer shaly facies are known to contain significant amounts of kerogen (up to 20%), enriched in metals such as uranium and precious metals . However, conventional ore treatment methods usually fail in the recovery of valuable metals from this organic material.
The actual role of the organic matter in the formation of ore deposits is questioned since its chemical and physical properties are very different from that of the mineral phases. Such consideration may be relevant in the case of black shale processing and will be further investigated in the project.
In France, copper production was quite limited compared to other countries (< 100,000 t). Significant reserves have, however, been identified in the Massif Central, in Brittany which could be an interesting and feasible target to restart French mining activities. Those deposits are polymetallic with Cu being found mostly in the form of chalcopyrite. In addition to French primary ore, historical mining activities also generated significant volumes of tailings characterized by various mineral assemblages, including valuable (Cu, Pb, Zn, Ag, Au…) and toxic (As, Cd,…) metals.