technologyComment of kaolin production (RER, RoW): There exist two different processes for the production of market kaolin - a dry and a wet process. The first one - the dry process - is relatively simple but yields therefore also a lower quality product, reflecting the quality found in the crude kaolin. The wet process on the other hand side is used to produce filler and coating grades. It is this process that is modeled in this dataset. The most important four steps of the wet process are the following: - Mining: Nowadays most of kaolin mining is done in open pit mining. Depending on the composi-tion, either mining with shovels, draglines, motorized scrapers and front-end loaders is done (e.g. Georgia, USA) or mining with high-pressure hydraulic monitors (e.g. Cornwall, UK) is done. In the second case, a stream of water is washing out the fine particle kaolin and is leaving the coarse quartz and mica residues within the soil. - Mineral separation (degritting): Kaolin beeing a mineral, it is obvious that there are always also other minerals (the grit) in the kaolin deposits, which have to be separated. To separate two miner-als, either physical or chemical differences between the two substances are taken as base. In gen-eral, the mined kaolin is mixed therefore with water and a dispersing chemical to form a slurry that is then degritted (by e.g. rake classifiers, hydrocyclones or screens). - Kaolin benefication: When the separated kaolin fullfills not the specification asked a benefication process is added to improve e.g. the brightness (either by magnetic separation or by bleaching with ozone or hydrogen peroxide), the rheology (by blending different kaolins), the purity (either by blending or by magnetic separation) or the grain size distribution (again blending as a possibility). In this step, the producer is also deciding the form of delivery (bulk, powder, slurry). - Storage & transport: The storage is done either in silos (bulk and powder) or in tanks (slurries). Due to the fact that customers more and more apply for the 'just in time' principle, the storage ca-pacities of the producers are increasing and the transports are done more and more by lorry to the customer (more flexible than other means of transport). References: Hischier R. (2007) Life Cycle Inventories of Packagings & Graphical Papers. ecoinvent report No. 11. Swiss Centre for Life Cycle Inventories, Dübendorf, 2007.
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.
technologyComment of bentonite quarry operation (DE, RoW): The technology used in the modelled German mine is probably state-of-art (first mining company in Europe taking part at an eco-audit based on EG-eco-audit requirements). The assumed thickness of the bentonite layer is 3 m. The thickness of overburden material is estimated to be 30 m. Digging and transportation is made by heavy diesel machines. Reference: 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.
technologyComment of gravel and sand quarry operation (CH): The typical technology for swiss gravel and sand mining was assumed.
technologyComment of gravel and sand quarry operation (CH): The typical technology for swiss gravel and sand mining was assumed.
technologyComment of shale quarry operation (RoW): Typical technology for Quebec shale mining
technologyComment of gypsum quarry operation (CH): open pit mining; composition of products: 65% gypsum, 34% anhydrite, 1% others.
technologyComment of pumice quarry operation (DE, RoW): technology unknown
technologyComment of limestone production, crushed, washed (RoW): The company works on a technically high level; heavy machines (excl. building machines) are operated electrically; air recirculated in closed loop to avoid dust emissions; ground water used for washing.
technologyComment of perlite quarry operation (DE, RoW): Technology of vermiculite mining used.