Study of a copper slag from a 13th-century BC tomb at Enkomi, CyprusLéon Brun

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This operation therefore results in a mixture complex of iron sulphide, iron oxide, desulfure de copper and copper oxide. We find in the sample all of these bodies, some in amorphous state, the others in crystallised state.

2 (Fe2S3) + O11 = Fe2O3 + 2 (FeS) + 4SO2

and an iron sulphide into iron oxide:

Cu2S + 2O2 = 2 (CuO) + SO2

In the operation of roasting and smelting a sulphurous ore, one observes a transformation of the sulphide of copper initially into copper oxide:

These analyses show that the sample is rich in iron and poor in copper. Its composition is very sensibly that which would result after roasting and smelting a sulphurous iron and copper mineral such as chalcopyrite for example, from which one would have removed by a metallurgical operation a large part of the copper.

We note that in this slag there does not exist any metals other than iron and copper.

This analysis confirms well enough after the first which should represent the average analysis of the sample.

Loss on ignition ........................ 6,98 Silica SiO2 ........................ 15,60 Alumina Al2O3 ........................ 1,70 Iron oxide Fe2O3 ........................ 64,70 Copper oxide CuO ........................ 5,80 Phosphoric anhydride P2O5 ........................ 0,40 Manganese MnO ........................ Traces non dosables Lime CaO ........................ 1,50 Magnesia MgO ........................ Traces non dosables Sulphur of sulphides ........................ 3,37

Another analysis made on small pieces detached at the moment of fragmentation gave:

Loss on ignition ........................ 5,21 SiO2 ........................ 17,60 Al2O3 ........................ 2,10 Fe2O3 ........................ 69,49 CuO ........................ 1,40 P2O5 ........................ Traces MnO ........................ Traces CaO ........................ 1,50 MgO ........................ Traces Sulphur of sulphides ........................ 2,39

a fragmented material of which one wishes to keep a part important as a witness and for later study.

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