Description: 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). technologyComment of silica sand production (DE, RoW): Generally there are no differences in the quarrying process of silica sand compared to the “normal” sand process. An important difference is that silica sand is dried. It is assumed that the content of moisture before drying is about 5% and afterwards around 1%. Another difference is based on the high content of SiO2, which makes the raw material rarer. Losses in the conveyor belt transportation are taken into account.
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 'silica sand', 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: cryolite production, from fluosilicic acid, GLO: 0.000275161844289697 silica sand production, DE: 0.0661972972575346 silica sand production, RoW: 0.933527540898176 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 generalComment of silica sand production (DE, RoW): This dataset represents the production of 1 kg of silica sand obtained by the drying of sand. Silica sand is a special sand with a SiO2 (Quartz)-content of more than 85% (w/w). If the SiO2-content is higher than 98%, the silica sand is called pure silica sand or industrial sand. Pure silica sand with a SiO2-content over 99% and heavy metal content (especially iron compounds) under 0.05% is called “vitreous“ sand. Important silica sand deposits are found in Germany: Niedersachsen, Westfalen and Niederrhein (Bach et al. (1999)). The use of silica sand is subdivided in two categories (Bach et al. (1999)): 1. Building sand: used as aggregate for concrete, mortar, plaster, dumping, non-freezing, used for the production of sand-lime bricks and as paring and brake sand. 2. Industrial sand: glass-, grinding-, enamel-, oil-, moulding- and filter sand Apart from the use in the building sector, silica sand is also used in the beverage industry, as a raw material for the chemical industry, for the production of refractories, as filling material or for the covering of playing fields. References: Bach M., Rohlf U. and Frunder B. (1999) Römpp Lexikon Chemie. Georg Thieme Verlag, Stuttgart. Kellenberger D., Althaus H.-J., Jungbluth N., Künniger T., Lehmann M. and Thalmann P. (2007) Life Cycle Inventories of Building Products. Final report ecoinvent Data v2.0 No. 7. EMPA Dübendorf, Swiss Centre for Life Cycle Inventories, Dübendorf, CH.
Origin: /Bund/UBA/ProBas
Tags: Natriumhydroxid ? Siliziumdioxid ? Flusssäure ? Main ? Feuchtigkeitsmessung ? Sand ? Abgrabung ? Rohstoff ? Verkehr ? Mining and quarrying ? Other mining and quarrying ? Quarrying of stone, sand and clay ?
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Language: Deutsch
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