Search Results (8)

This article examines the impact of artisanal and small-scale mining (ASM) on livelihood in mining communities in Rwanda (Rutsiro) where wolframite and coltan are mined. The paper discusses the development of ASM and other entrepreneur activities, in particular agriculture. With ASM activities, there is environmental degradation on the one hand but also an improvement in the well-being of the local population on the other. The 3T (tin, tungsten, tantalum) minerals extracted by ASM are used in the electronics industry for products such as smartphones, tablets, and laptops, which are mainly consumed in the developed world. Based on questionnaires and structured research with miners, it was determined how ASM affects their lives, or whether there is a deterioration or improvement in their well-being. The research builds on previous field research in Rwanda. Because of mining, communities in the mining areas have access to health care, they can pay tuition fees, insurance, etc. On the other hand, the lives of miners are endangered by respiratory diseases, accidents in mines, landslides in mining areas, and other negative environmental impacts. The extraction of these minerals, however, may lead to a worse quality of life for the miners responsible for the extraction in developing countries. This different view is also illustrated by the fact that miners themselves often do not know what 3T minerals are used for. ASM benefits miners from an economic perspective but may worsen their quality of life due to unsuitable working conditions. This study covers a broader understanding of socioeconomic impacts of ASM and tries to point out the lack of awareness about the mining of minerals important for the daily use of modern technologies. This article would like to contribute to the larger debate about the lack of awareness of the origin of 3T minerals. Full article

The Mesoproterozoic Kibaran belts host large amounts of mineral resources such as cassiterite, wolframite, gold, and columbite-group minerals (“coltan”), all of them in high demand for new technologies and related industries. Most of these mineral occurrences are linked to the latest Mesoproterozoic to early Neoproterozoic G4 granitoid intrusions, also termed “tin(-bearing) granites”. Three main parts constitute the Kibaran belts: the Kibaride Belt (KIB) in the south, the Karagwe-Ankole Belt (KAB) in the east, and the Kivu Belt (KVB) in the west. Geological detail concerning the metallogeny of the KVB, which hosts large parts of these mineral resources, is very sparse. Previously, there was an assumed time gap of about 200 Ma between the formation of the last Kibaran terranes (1250 to 1200 Ma) and the emplacement of the G4 granites (ca. 1050 to 970 Ma), which generated the main mineralizations. Recent studies dated the last Kibaran tectono-thermal events younger than 1120 to 1110 Ma, which gave evidence for a drastic reduction in this time gap. Thus, the two newly recognized tectono-thermal events have likely contributed to the remobilization of older mineralized granites. These new data allow us to link the G4 granitoids and the associated mineralizations with the terminal Kibaran orogeny. However, the G4 emplacement and its relationships with older granites, with their host rocks and associated mineralizations, are not yet understood. Here, the main occurrences of the KVB are reviewed, and comparisons with similar mineralizations in the adjacent KAB are undertaken to improve our understanding on these complex relationships. Full article

Niobium and tantalum are mainly produced from columbite–tantalite ores, and 60% of their production is nowadays located in the Democratic Republic of Congo and Rwanda. The concentration of supply, the scarcity, the wide range of use in all electronic devices, and the expected future demand boosted by the clean and digital transition means that Nb and Ta have high supply risks. In this context, extraction from rich Ta and Nb tailings from abandoned mines could partly offset such risks. This study analyzes the energy cost that the reprocessing of both elements from tailings would have. To that end, we simulate with HSC Chemistry software the different processes needed to beneficiate and refine both metals from zinc tailings as a function of Nb and Ta concentration. At current energy and metal prices, tantalum recovery from rich Ta-Nb tailings would be cost-effective if ore-handling costs were allocated to a paying metal. By way of contrast, niobium recovery would not be favored unless market prices increase. Full article

A novel approach for Ta and Nb extraction consisting of the pre-treatment of a coltan-bearing ore with an ammonium bifluoride sub-molten salt and subsequent acid leaching has been studied. The effects from ore granulometry, ammonium bifluoride (ABF) to ore mass ratio, temperature and duration of fluorination on the degree of Ta and Nb extraction were examined. The ABF to ore ratio and process temperature were found to have the most pronounced impact on extraction efficiency. The following optimal process conditions were determined: ore granulometric fraction (−75 + 45 µm), ABF-ore (5/1), fluorination temperature (200 °C) and fluorination time (2.5 h). Maintaining these parameters enabled about 94% of Ta and 95% of Nb to be brought into solution during the sulfuric-acid-leaching stage. A comparison of the proposed method with previously reported studies suggests that due to the effects of mechanical agitation and the recirculation of the HF-containing gaseous phase back into the process, the dosage rate of ABF at the fluorination stage could be reduced significantly without sacrificing the overall recovery of Ta and Nb. In such a way, the approach could offer added environmental benefits since release of fluoride-containing effluents into the environment could be limited. Full article

Demand for niobium and tantalum is increasing exponentially as these are essential ingredients for the manufacture of, among others, capacitors in technological devices and ferroniobium. Mine tailings rich in such elements could constitute an important source of Nb and Ta in the future and alleviate potential supply risks. This paper evaluates the possibility of recovering niobium and tantalum from the slags generated during the tin beneficiation process of mine tailings from the old Penouta mine, located in Spain. To do so, a simulation of the processes required to beneficiate and refine both elements is carried out. After carbothermic tin reduction, the slags are sent to a hydrometallurgical process where niobium oxide and tantalum oxide are obtained at the end. Reagents, water, and energy consumption, in addition to emissions, effluents, and product yields, are assessed. Certain factors were identified as critical, and recirculation was encouraged in the model to maximise production and minimise reagents’ use and wastes. With this simulation, considering 3000 production hours per year, the metal output from the tailings of the old mine could cover around 1% and 7.4% of the world annual Nb and Ta demand, respectively. Full article

Within due diligence concepts for raw material supply chains, the traceability of a shipment is a major aspect that has to be taken into account. Cassiterite and coltan are two so-called conflict minerals for which traceability systems have been established. To provide additional credibility to document-based traceability systems the German Federal Institute for Geosciences and Natural Resources (BGR) has developed the analytical fingerprint (AFP) for the minerals coltan, cassiterite, and wolframite. AFP is based on the analysis of a sample from a shipment with a declared origin and evaluates whether the declared origin is plausible or not. This is done by comparison to reference samples previously taken at the declared mine site. In addition to the generation of the analytical data, the data evaluation step, with the aim to state whether the declared origin is plausible or not, is of special importance. Two data evaluation approaches named “Kolmogorov–Smirnov distance (KS-D) approach” and “areas ratio approach” are applied to coltan and cassiterite and result in very low rates of false negative results, which is desired for AFP. The areas ratio approach based on hypothesis testing and a more sophisticated evaluation of the multivariate data structure has some advantages in terms of producing lower rates of false positive results compared to the KS-D approach. Full article

Conflict minerals are those mined in politically unstable regions of the world and are then sold to finance war or other illegal activities. Industrial manufacturers are required to show that minerals used in their applications are not derived from conflict areas. Several geochemical and geochronological methods have been suggested to fingerprint conflict minerals; however, all these methods require sophisticated and extensive laboratory procedures. Portable X-ray fluorescence data of 108 samples from various location in Democratic Republic of the Congo shows that cassiterite and wolframite ores from all studied regions can be fingerprinted using various discrimination diagrams. Coltan ore samples from several regions can also be discriminated using major and trace elements of these samples. In addition, patterns in chondrite-normalized spider diagrams for each region are unique and can be used as fingerprinting tools. Full article