Читать книгу Encyclopedia of Glass Science, Technology, History, and Culture - Группа авторов - Страница 59

The particle (or grain) size distribution (PSD) is a crucial parameter of individual raw materials. The required PSD may be costly to achieve. It primarily depends on the hardness of the bulk material, which in turn roughly correlates with its melting temperature [5]. As examples, K‐feldspar has a hardness of 6 (out of a maximum of 10) on the Mohs scale and melts at about 1200 °C, quartz has a hardness of 7 and melts above 1700 °C (in the form of cristobalite), whereas corundum (α‐Al₂O₃) has a hardness of 9 and melts above 2000 °C. Hence, the glassmaker determines the final PSD of the raw material as a compromise between meltability, furnace technology, and price (cost) while also limiting the unnecessary fines that generate dust and furnace carryovers. For specific applications, the glassmaker may in addition request the supplier of raw material to cut the lower end of the PSD to get totally rid of dust from fines.

The sieve PSD curves of a variety of important raw materials are compared in Figure 2 to illustrate their variations with composition and overall batch meltability. The median diameter representing 50% of a sieved raw material is termed D50. For quartz, it ranges from 200 to 300 μm when sand is used for standard window or bottle glass but is much lower at 50–100 μm for the flour, for instance, used as SiO₂‐carrier for E‐glass fiber, a peraluminous, boron‐bearing, alkaline earth silicate (Chapter 1.5). At the other end, the D50 of limestone and dolomite may exceed 1 mm and that of basalt for insulating glass applications may even be 10 times larger because chemical heterogeneities are in this case much smaller than within a mixture of raw materials.

Table 1 Natural and synthetic raw materials compositions and prices.

Oxide	Raw material	Bulk chemistry	Overall mineralogy	Sp – Fr – It – De	Price €/T*
SiO2	Quartz‐sand	>95 % SiO2; H2O, Al2O3, RO, R2O, Fe2O3	Quartz, free‐water, mica, feldspars	Arena – Sable – Sabbia – Sand	20–200€/T
Sandstone	>95 % SiO2; H2O, Al2O3, RO, R2O, Fe2O3	Quartz, mica, feldspars, FeTi‐oxides, free‐water	Arenisca – Grès – Arenaria – Sandstein
Quartzite	>95 % SiO2; H2O, Al2O3, RO, R2O, Fe2O3	Quartz, mica, feldspars, FeTi‐oxides	Cuarcita – Quartzite – Quarzite – Quarzit
Al2O3, R2O	Feldspar (concentrates from greywacke, arkose, pegmatite, granite, etc.)	17–20 % Al2O3; 11–15 % R2O; <65 % SiO2; H2O; Fe2O3, TiO2, CaO	Alkali‐feldspars [(K,Na)AlSi3O8: orthoclase, microcline, sanidine, albite, and their solid solutions], quartz (15–20%), micas. Li‐rich (up to 1.5 wt %) contain spodumene, petalite, or lepidolite (Li‐mica), mainly.	Feldespato – Feldspath – Feldspato – Feldspat	80–150€/T
Nepheline(−syenite)	20–26 % Al2O3; 15–18 % R2O; <56 % SiO2; H2O; Fe2O3, TiO2, CaO	Alkali‐feldspars [(K,Na)AlSi3O8: microcline, sanidine, albite, and their solid solutions], alkali‐feldspatoids [(K,Na)AlSiO4: nepheline, kalsilite, and their solid solutions], micas, titanite, perovskite, garnet, zircon, apatite, REE‐silicates. Silica undersaturated = no quartz	Nefelina – Néphéline – Nefelina – Nephelin	100–130€/T
Phonolite	20–26 % Al2O3; 15–18 % R2O; <56 % SiO2; H2O; Fe2O3, TiO2, CaO	Alkali‐feldspars [(K,Na)AlSi3O8: sanidine, albite, and their solid,solutions], alkali‐feldspatoids [(K,Na)AlSiO4: nepheline, kalsilite, and their solid,solutions], leucite KAlSi2O6, sodalite, haüyne, carnegeite, micas, amphibole, pyroxene, titanite, ilmenite, perovskite. Silica undersaturated = no quartz	Fonolita – Phonolite – Fonolite – Phonolith	60–70€/T
Anorthosite	<30 % Al2O3, <15 % CaO, <45 % SiO2, Fe2O3, R2O, MgO	Anorthite CaAl2Si2O8, pyroxene, amphibole
Al2O3	Bauxite (raw or calcined)	40 % < Al2O3 < 80 %; 10–15 % Fe2O3; H2O; SiO2	Gibbsite Al(OH)3, diaspore α‐AlO(OH), boehmite y‐AlO(OH), bayerite, corundum, goethite, hematite, kaolin, anatase	Bauxita – Bauxite – Bauxite – Bauxit	250–400€/T
Hydrated alumina	>60 % Al2 O3 , H2 O, Fe2 O3 , SiO2	Al(OH)3 polymorphs		250–300€/T
Calcined alumina	99 % Al2 O3 , Fe2 O3 , SiO2	Corundum		500–600€/T
Kaoline	>45 % SiO2, >35 % Al2O3, 13–14 % H2O, Fe2O3	Kaolinite Al2Si2O5(OH)4, quartz	Caolín – Kaolin – Caolino – Kaolin	100–300 €/T
Pyrophyllite	>65 % SiO2, >25 % Al2O3, H2O	Pyrophyllite Al2Si4O10(OH)2, quartz
Na2O	Na‐carbonate (soda ash)	58 % Na2 O, 42 % CO2	Natrite Na2 CO3 , natron Na2 (CO3 ) · 10 H2 O, trona Na2 CO3 · NaHCO3 · 2 H2 O	Soda – Na‐carbonate (Soude) – Soda – Soda	150–300 €/T
Albite	67 % SiO2, 20 % Al2O3, 11 % Na2O, K2O	Albite NaAlSi3O8
K2O	K‐carbonate	58 % K2 O, 42 % CO2	K2 CO3	Potasa – Potasse – Potassio – Pottasche	500–1500 €/T
CaO	Limestone	56 % CaO, 44 % CO2, MgO, SiO2	Calcite CaCO3, dolomite, quartz	Caliza – Calcaire – Calcare – Kalkstein	20–40 €/T
Burnt lime	>98 % CaO, H2 O	CaO, Ca(OH) 2	Cal – Chaux – Calce – gebranntes Kalk
Marble	56 % CaO, 44 % CO2, MgO, SiO2	Calcite CaCO3, dolomite, quartz	Marmol – Marbre – Marmo – Marmor
Wollastonite	48 % CaO, 52 % SiO2	Wollastonite CaSiO3		80–450 €/T
MgO	Dolomite	30 % CaO, 22 % MgO, 47 % CO2, SiO2	Dolomite CaMg(CO3)2	Dolomie – Dolomie – Dolomia – Dolomit	20–40 €/T
Magnesite	48 % MgO, 52 % CO2, CaO	Magnesite MgCO3		250–400 €/T
Talc	32 % MgO, 63 % SiO2, <5 % H2O	Talc Mg3Si4O10(OH)2	Talco – Talc – Talco – Talk	100–300 €/T
Basalt	<10 % MgO, <15 % Al2O3, <12 % Fe2O3, <12 % CaO, <44 % SiO2, TiO2, R2O	Olivine, pyroxene, plagioclase, amphibole	Basalto – Basalte – Basalto – Basalt	10–20 €/T
Li2O	Li‐carbonate	40 % Li2 O, 60 % CO2	Zabuyelite Li2 CO3 , Li(OH)2		5000–5020 k €/T
Spodumene (concentrate from pegmatite)	7 % Li2O, 27 % Al2O3, 65 % SiO2	Spodumene LiAlSi2O6, quartz		900–1000 €/T
Petalite (concentrate from pegmatite)	4 % Li2O, 16 % Al2O3, 78 % SiO2	Petalite LiAlSi4O10		800–900 €/T
B2O3	Colemanite	50 % B2O3, 27 % CaO, 20 % H2O, SiO2	Ca2B6O11·5 H2O, Ca2B6O8(OH)6·2 H2O		400–600 €/T
Ulexite	42 % B2O3, 13 % CaO, 35 % H2O, 7 % Na2O	NaCaB5O6(OH)6·5 H2O		350–450 €/T
Borax	35 % B2O3, 45 % H2O, 15 % Na2O	Na2 B4 O7 ·10 H2 O, Na2 B4 O5 (OH)4 ·8 H2 O	Borax – Borax – Borace – Borax	350–500 €/T
Boric acid	56 % B2 O3 , 44 % H2 O	Sassolite H3 BO3	Acido borico – Acide borique – Acido borico – Borsäure	650–1000 €/T
BaO	Ba‐nitrate	58 % BaO, 42 % NOx	BaNO 3		1200–1300 €/T
Ba‐carbonate	78 % BaO, 22 % CO 2	Witherite BaCO 3		350–800 €/T
F	Fluorspar	49 % F, 72 % CaO equivalent	Fluorite CaF2	Fluorita – Spath Fluor – Fluorite – Flußspath	300 €/T
SO3	Na sulphate	56 % SO3 , 44 % Na2 O	Thenardite Na2 SO4	Sulfato – Solphate – Solfato – Sulfat	100 €/T
Gypsum	46 % SO3, 32 % CaO, 21 % H2O	Gypsum CaSO4·2H2O	Yeso – Gypse – Gesso – Gips	10 €/T
	Anhydrite	59 % SO3 , 41 % CaO	Anhydrite CaSO 4	Anhidrita – Anhydrite – Anidrite – Anhydrit	30 €/T
Fe2O3	Iron‐oxide	>98 % Fe2O3, FeO	Hematite Fe2O3, magnetite	Hierro – Fér – Ferro – Eisen	100–2000 €/T
Cr2O3	Chromite	68 % Cr2O3, 32 % FeO	Chromite FeCr2O4, (Fe,Mg)(Cr,Al,Fe)2O4 magnesio‐chromite – spinel solid solution	Cromita – Chromite – Cromite – Chromit	300–500 €/T
TiO2	Rutile	>98 % TiO2, Fe2O3	Rutile TiO2, anatase, ilmenite, titanite	Rutilo – Rutile – Rutilo – Rutil	1400–1500 €/T
Ilmenite	52 % TiO2, 48 % FeO, SiO2	Ilmenite FeTiO3		150–200 €/T
ZrO2	Zircon	70 % ZrO2, 30 % SiO2, HfO2, REE, Fe2O3, TiO2	Zircon ZrSiO4	Circón – Zircon – Zircone – Zirkon	1100–1200 €/T
P2O5	Ca‐phosphate	35 % < P2O5 < 45 %, 35 % < CaO < 45 %, R2O, H2O, F	Apatite Ca5(PO4)3(OH, F, Cl)	Fosfato – Phosphate – Fosfato – Phosphat	500–1000 €/T
V2 O5	Vanadium‐oxide	>98 % V2 O5			15,500 €/T
C	Coke	>90 % fixed‐C	Coke		100–200 €/T
Reducers	Slag	30–40 % CaO, 30–40 % SiO2 , 10–15 % Al2 O3	Glass		50–200 €/T
O2	Cassiterite	>98 % SnO2	Cassiterite SnO2		16,000 €/T
As‐oxide, As acid	>98 % As2 O5			>2500 €/T
Sb‐oxide	>98 % Sb2 O5
Colorants	Se, Co, Cu, Cd, Mn

Prices only indicative as actual quotations strongly depend on quality (grain size distribution, iron content, and overall impurities), volumes, transportation costs (quarry‐to‐plant distance and transportation mode) and, of course, market‐price fluctuations. RO = CaO and MgO; R₂O = Na₂O + K₂O.

Figure 1 Comparison between the compositions of the main raw materials used in glassmaking and those of some important glass products as projected in the pseudo‐ternary Al₂O₃–R₂O + CaO–SiO₂ diagram.

Figure 2 Sieve particle size distribution (PSD) curves of the main raw materials used in glassmaking (<40 μm laser PSD domain). The D50 is the median diameter representing 50% of a sieved raw material. The steeper the curve, the more homogeneous is the PSD.