Description: technologyComment of fluorspar production, 97% purity (GLO): Open cast mining of resource. Separation by crushing, grinding and flotation. technologyComment of scandium oxide production, from rare earth tailings (CN-NM): See general comment.
Types:
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text_type: Report,
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Comment: This is a market activity. Each market represents the consumption mix of a product in a given geography, connecting suppliers with consumers of the same product in the same geographical area. Markets group the producers and also the imports of the product (if relevant) within the same geographical area. They also account for transport to the consumer and for the losses during that process, when relevant. This is the market for 'fluorspar, 97% purity', in the Global geography. Transport from producers to consumers of this product in the geography covered by the market is included. This market is supplied by the following activities with the given share: fluorspar production, 97% purity, GLO: 0.978553836696021 scandium oxide production, from rare earth tailings, CN-NM: 0.021446163303979 generalComment of fluorspar production, 97% purity (GLO): Basic inventory based on old literature information. [This dataset was already contained in the ecoinvent database version 2. It was not individually updated during the transfer to ecoinvent version 3. Life Cycle Impact Assessment results may still have changed, as they are affected by changes in the supply chain, i.e. in other datasets. This dataset was generated following the ecoinvent quality guidelines for version 2. It may have been subject to central changes described in the ecoinvent version 3 change report (http://www.ecoinvent.org/database/ecoinvent-version-3/reports-of-changes/), and the results of the central updates were reviewed extensively. The changes added e.g. consistent water flows and other information throughout the database. The documentation of this dataset can be found in the ecoinvent reports of version 2, which are still available via the ecoinvent website. The change report linked above covers all central changes that were made during the conversion process.] generalComment of scandium oxide production, from rare earth tailings (CN-NM): This dataset refers to the beneficiation and smelting activities in order to produce 1 kg of Scandium oxide (Sc2O3), with purity greater than 99.9% from rare earth tailings in the Bayan obo mines in the Baotou region of China. The rare earth tailings are produced as a byproduct from the mining and beneficiation activities of the REE-Nb-Fe ore at the same location. China is top producer of Scandium, being responsible for 90% of the global scandium production (Source: https://www.scandiummining.com/site/assets/files/5740/scandium-white-paperemc-website-june-2014-.pdf). Today, scandium is produced either as a co-product of other primary metal projects or is extracted out of old tailings from depleted mining projects where the specific process happened to concentrate scandium levels. (Source: https://www.scandiummining.com/scandium/scandium-faq/). This dataset is based on the publication of Wang et al (2020) (reference 1). The boundaries of the system have been expanded in order to include the processing of fluorite coarse ore that is produced as a byproduct during the scandium oxide production, due to the fact that there was no available proxy for the ore in Ecoinvent, The processing produces fluorite concentrate which was represented as fluorspar which exists in Ecoinvent. The data for the processing of fluorite was taken from Wang et al 2019 (reference 2 – consult the respective exchange comment). Due to lack of data regarding the data acquisition time, the dataset generator has relied on the previous work of the same author that dealt with the production of scandium concentrate from the Bayan Obo tailings (see reference 2 –data coverage until the beneficiation stage). Wang et al 2019 mentions that the data were acquired during 2014-2018. Therefore, because the data is recent, the dataset is assumed valid from 2018 until 2022 (5 years). Furthermore, the electricity is taken from the grid, meaning that all upstream inputs and outputs are already taken into account. Finally, the steam is generated from coal burning. For further information, consult the sampling procedure and the individual exchange comments. Reference 1: Wang, L., Wang, P., Chen, W.-Q., Wang, Q.-Q., & Lu, H.-S. (2020). Environmental Impacts of Scandium Oxide Production from Rare Earths Tailings of Bayan Obo Mine. Journal of Cleaner Produc-tion, 122464. doi:https://doi.org/10.1016/j.jclepro.2020.122464 Reference 2: Wang, L., Jiao, G., Lu, H., & Wang, Q. (2019). Life cycle assessment of integrated exploitation technology for tailings in Bayan Obo Mine, China. Applied Ecology and Environmental Research, 17, 4343-4359. doi:10.15666/aeer/1702_43434359 This dataset includes the beneficiation stage and the smelting stage, including 5 major processes and 22 sub-processes. The first stage consists of 3 separation steps (i.e first separation, secondary separation, and final separation), during which scandium is separated and concentrated to produce Scandium (Sc) concentrate for the smelting stage. During the smelting stage – consisting of metallurgy and purification processes – Sc oxide is extracted from the concentrate to produce high-purity (>99.9%) Sc2O3. Beneficiation stage: The beneficiation stage is comprised of the first, secondary and final separation. During the first separation, the remaining iron and rare earth elements (REEs) are separated from the REE tailings, through the sub-processes of iron separation, REE separation). Afterwards, bulk flotation is applied to the remaining tailings, dividing them into mixed foam and mixed grit, in order to separate easily flotating and iron-silicate minerals and reduce the difficulty of the next recycling. The mixed foam separates fluorite and the mixed grit, containing approximately 0.02-0.03% scandium. Then the mix grit goes to the secondary separation (including the sub-processes of sulfur flotation (I), iron separation (II), gravity concentration, sulfur flotation (II), and Fe separation (III) in order to separate the sulfur and the remaining iron (byproducts) and thus further enrich the scandium. Sulfur flotation (I) and further iron separation is necessary in order to decrease the difficulty of Niobium (Nb) separation. Then gravity separation is performed in order to isolate the gangue materials from the grit, and simplify the Nb separation. At this point, the original tailings have been reduced to concentrates and Scandium-enriched remaining tailings (with 0.02-0.03% Sc content). The concentrates undergo again sulfur flotation (I) and iron separation (II) to further separate iron and sulfur and -as a result- further enrich the scandium in the remaining tailings, reaching a content of 0.03-0.04% Sc. After the first and secondary separation, iron, sulfur and REEs have been completely separated and the remaining valuable elements to be extracted from the tailings contain Nb and Sc. Nb separation is performed first, because of the Sc existence in silicate materials. Pyroxene and amphibole (silicate minerals) are recycled by a strong magnetic separation process and divided from the Nb tailings and gravity concentration tailings, producing high-quality Sc concentrates (approximately 0.05% Sc content). The concentrates are then fed to the smelting stage for the production of high purity Sc2O3. Smelting stage: The smelting stage consists of the metallurgy and the purification process. The metallurgy step incorporates the processes of concentration, ore grinding, and pressure filtration (physical extraction), normal acid leaching, pressure acid leaching, and extraction. The Sc concentrates produced from the beneficiation step are further concentrated and the residues are grinded (particle size reach 200-325 mesh) to the output rate. Pressure filtration separates the solid and liquid containing Scandium. After that, (normal and pressurized) acid leaching is applied to extract the Scandium-containing substance (20-30% Sc content) from the acid leaching solution, which goes to the purification process, which includes 6 sub-processes: Ti cleaning, Fe cleaning, back extraction, purification, oxalic acid precipitation, and calcination. At first, residual titanium and iron are removed first to avoid impacting the further purification sub-processes. The ideal cleaning rate can be attained by applying high number of washing steps (i.e. 20). However too much washing can potentially lead to significant scandium losses. Then, the addition of sodium hydroxide within the Sc-containing solution produces a soda cake, containing Nb and Sc. Subsequently, niobium and scandium oxide are produced from filter cake and filtrate respectively, which are created through purification of the soda cake, after the addition of hydrochloric acid solution. Excessive addition of oxalic acid to the filtrate produces scandium oxalate precipitates, which are later burned at a temperature of 800°C in order to produce high-purity (>99.9%) scandium oxide (Sc2O3).
Origin: /Bund/UBA/ProBas
Tags: Scandium ? Seltene Erden ? Tagebau ? Bergematerial ? Flotation ? Flussspat ? Ressource ? Mining and quarrying ? Mining and quarrying n.e.c. ? Mining of chemical and fertilizer minerals ? Other mining and quarrying ?
License: unbekannt
Language: Deutsch
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