New perspectives on quantitative textural analysis

Process mineralogy provides the mineralogical information required by geometallurgists to address the inherent variation of geological data. The successful benefitiation of ores mostly depends on the ability of mineral processing to be efficiently adapted to the ore characteristics, being liberation one of the most relevant mineralogical parameters. The liberation characteristics of ores are intimately related to mineral texture. Therefore, the characterization of liberation necessarily requieres the identification and quantification of those textural features with a major bearing on mineral liberation. From this point of view grain size, bonding between mineral grains and intergrowth types are considered as the most influential textural attributes. While the quantification of grain size is a usual output of automated current technologies, information about grain boundaries and intergrowth types is usually descriptive and difficult to quantify to be included in the geometallurgical model. Aiming at the systematic and quantitative analysis of the intergrowth type within mineral particles, a new methodology based on digital image analysis has been developed. In this work, the ability of this methodology to achieve a more complete characterization of liberation is explored by the analysis of chalcopyrite in the rougher concentrate of the Kansanshi copper-gold mine (Zambia). Results obtained show that the method provides valuable textural information to achieve a better understanding of mineral behaviour during concentration processes. The potential of this method is enhanced by the fact that it provides data unavailable by current technologies. This opens up new perspectives on the quantitative analysis of mineral processing performance based on textural attributes.

Composition of bottom sediments from the anoxic Mogil'noe Lake, Kil'din Island (Barents Sea)

In summer 2006 integrated geological, geochemical, hydrological, and hydrochemical studies were carried out in the relict anoxic Mogil'noe Lake (down to 16 m depths) located in the Kil'din Island in the Barents Sea. Chemical and grain size compositions of bottom sediments from the lake (permanently anoxic basin) and from the Baltic Sea deeps (periodically anoxic basins) were compared. Vertical location of the hydrogen sulfide layer boundary in the lake (9-11 m depths) was practically the same from 1974 up to now. Concentrations of suspended matter in the lake in June and July 2006 appeared to be close to its summer concentrations in seawater of the open Baltic Sea. Muds from the Mogil'noe Lake compared to those of the Baltic Sea deeps are characterized by fluid and flake consistency and by pronounced admixtures of sandy and silty fractions (probably of eolic origin). Lacustrine mud contains much plant remains; iron sulfides and vivianite were also found. Concentrations of 22 elements determined in lacustrine bottom sediments were of the same levels as those found here 33 years ago. Concentrations also appeared to be close to those in corresponding grain size types of bottom sediments in the Baltic Sea. Low C_org/N values (aver. 5.0) in muds of the Mogil'noe Lake compared to ones for muds of the Baltic Sea deeps (aver. 10) evidence considerable planktogenic component in organic matter composition of the lacustrine muds. No indications were reveled for anthropogenic contaminations of the lacustrine bottom sediments with toxic metals.