Lithology and mineralisation types of the Rockliden Zn–Cu massive sulphide deposit, north-central Sweden: Implications for ore processing

Abstract

The Rockliden Zn-Cu volcanic-hosted massive sulphide deposit is located approximately 150 km south of the Skellefte ore district, north-central Sweden. Most of the mineralisation is found at the altered stratigraphic top of the felsic volcanic rocks, which are intercalated in the metamorphosed siliciclastic sedimentary rocks of the Bothnian Basin. Mafic dykes cross-cut all lithological units, including the massive sulphides, at the Rockliden deposit. The relatively high Sb grade of some parts of the mineralisation results in challenges in handling of the Cu-Pb concentrate in the smelting process. The aim of this study is to characterise different host rock units and ore types by their main mineralogy, as well as by their trace mineralogy with focus on the Sb-bearing minerals. Ore types are distinguished largely on the basis of their main base-metal bearing sulphide minerals, which are chalcopyrite and sphalerite. Several Sb-bearing minerals are documented and differences in the trace mineralogy between rock and ore types are highlighted. Based on the qualitative ore characterisation, rock-and ore-intrinsic parameters, such as the pyrite, pyrrhotite and magnetite content of the massive sulphides, the trace mineralogy and its association with base-metal sulphide minerals, are outlined and discussed in terms of relevance to the ore processing.

Particle-based Sb distribution model for Cu–Pb flotation as part of geometallurgical modelling at the polymetallic Rockliden deposit, north-central Sweden

“…However, it should be noted that the mineralogy of tested composite samples represents, by intention, extreme cases both in the main mineralogy and in the Sb trace mineralogy in respect to ore from the Rockliden deposit (Minz, Lasskogen, Wanhainen and Lamberg 2014;Minz et al 2015b). Holding experimental conditions constant in the flotation test does not mean that 5 Recovery-grade curves comparing results from the simulation with the experimental data (EPX).…”

“…The low number of samples (four) tested in the Rockliden case study, does not permit a model forecasting the recovery based on sound statistics connecting geological and processing parameters. Variations in the mineralogy within the Rockliden massive sulphide deposit were identified, in particular concerning the Sb mineralogy (Minz et al 2014). Thus, it is not recommended to base a model on a direct relation between drill core assays and processing parameters since the chemical assays might not accurately reflect the mineralogical variability potentially influencing processing parameters.…”

Distribution of Sb minerals in the Cu and Zn flotation of Rockliden massive sulphide ore in north-central Sweden

“…These samples represent two massive sulphide types outlined in qualitative studies on the Sb mineralogy of the Rockliden mineralisation . Additionally, Sb-rich ore types were described by qualitative ore characterisation of Rockliden (Minz et al, 2014). Testing of different ore types might allow linking the behaviour of Sb minerals in the flotation test with the 3D distribution of ore types in a geological model.…”

“…Testing of different ore types might allow linking the behaviour of Sb minerals in the flotation test with the 3D distribution of ore types in a geological model. A geological model of the deposit would then allow to evaluate the impact of Sb-rich ore types on the processing of the Rockliden mineralisation, but such model has been found difficult to implement (Minz et al, 2014). Further, ore-intrinsic parameters, i.e.…”

“…Rockliden is a polymetallic copper-zinc (Cu-Zn) massive sulphide deposit located in north-central Sweden (Minz et al, 2014). The inferred mineral resource is 9.2 Mt with 4.0 wt% Zn, 1.8 wt% Cu, 0.4 wt% Pb and 48 g/t Ag (New Boliden, 2014).…”