Description: technologyComment of cryolite production (RER, RoW): Production by the hydrofluoric acid technique. In a first step, alumina trihydrate is leached by hydrofluoric acid - in the second step cryolite is precipitated by adding sodium hydroxide. The overall process yield is of 98%. Inventory bases on stoechiometric calculations. The emissions to air (0.2 wt.% of HF input) and water were estimated using mass balance. technologyComment of cryolite production, from fluosilicic acid (GLO): The main production of cryolite involves hydrofluoric acid or fluosilicic acid. In both cases, the reactants can be combined with a variety of materials, such as Al2O3 · 3 H2O, Al2O3 · x NaOH, NaOH, NaCl, and Na2SO4. During the present reaction, fluosilicic acid is neutralised with sodium hydroxide. Then it reacts with Al2O3 to produce cryolite and silica. The reaction process is shown below: Al2O3 + 2H2SiF6 + 6 NaOH --> 2 Na3AlF6 + 2 SiO2 + 5 H2O It is difficult to predict how much of the cryolite is produced with the present reaction, since many production routes exist. The present inventory serves as an illustration of the cryolite production from fluosilicic acid. The alternative production route with HF is still considered to be the main production route (source: Ullmann encyclopedia, Cryolite, 2005).
Types:
Text { text_type: Report, }
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 'cryolite', in the Global geography. Transport from producers to consumers of this product in the geography covered by the market is included. cryolite' is an inorganic substance with a CAS no. : 015096-52-3. It is called 'trisodium;hexafluoroaluminum(3-)' under IUPAC naming and its molecular formula is: AlF6Na3. It is solid under normal conditions of temperature and pressure and appears as a colourless to white crystall, which is insoluble in water. It is modelled as a pure substance. On a consumer level, is used in the following products: explosives and welding & soldering products. There is no publicly available information about the consumption of this substance on industrial sites. This market is supplied by the following activities with the given share: cryolite production, from fluosilicic acid, GLO: 0.25 cryolite production, RER: 0.225903614457831 cryolite production, RoW: 0.524096385542169 generalComment of cryolite production (RER, RoW): The functional unit represent 1 kg of solid cryolite. Large uncertainty of the process data due to weak data on the production process and missing data on process emissions. [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 cryolite production, from fluosilicic acid (GLO): The dataset represents the production of cryolite from fluosilicic acid. The reaction yield is assumed to be 95% since no specific data is available. Water produced in the reaction is not considered as a byproduct, but assumed to be recovered and recycled internally. The reaction process is shown below: Al2O3 + 2H2SiF6 + 6 NaOH --> 2 Na3AlF6 + 2 SiO2 + 5 H2O
Origin: /Bund/UBA/ProBas
Tags: Aluminiumoxid ? Natriumhydroxid ? Siliziumdioxid ? Flusssäure ? Main ? Produktionstechnik ? Stoffbilanz ? Wasser ? Manufacture of basic chemicals ? Manufacture of basic chemicals, fertilizers and nitrogen compounds, plastics and synthetic rubber in primary forms ? Manufacture of chemicals and chemical products ? Manufacturing ?
License: unbekannt
Language: Deutsch
Accessed 1 times.