[0001] The present invention relates to mineral wool and particularly to advantageous combinations of raw materials for manufacturing mineral wool.

[0002] Manufacturing mineral wool requires simultaneously satisfying a plurality of often conflicting requirements. The chemical composition of mineral wool fibers must satisfy requirements including physical strength, resistance to humidity, bio- solubility, compatibility with manufacturing techniques and insusceptibility to variations in manufacturing tolerances whilst the raw materials used for producing the mineral fibers must satisfy requirements including availability in a form compatible with manufacturing techniques, security of supply and consistency of composition. Raw materials used for the manufacture of stone wool fibers may be selected from basalt, gabbro, dolomite, calcined alumina and recycled materials including stone wool fibers and slag. Raw material used for the manufacture of glass wool fibers may be selected from silica sand, feldspar, nepheline syenite, aplite, calcined alumina, hydrated alumina, soda-ash, limestone, dolomite, magnesite, recycled glass bottles, recycled glass sheets, borax pentahydrate, borax decahydrate and anhydrous borax.

[0003] According to one aspect, the present invention provides a method of making mineral wool fibers as defined in claim 1. The dependent claims define preferred or alternative embodiments.

[0004] The inventors have determined that mineral wool fibers having a chemical composition comprising:

55 to 75 wt%; SiO ₂ , and

5 to 20 wt% of the combination of CaO and MgO, and

5 to 20 wt% of the combination of Na2O and K2O, and

0 to 2 wt% total iron expressed as Fe2O3, and

an alkali/alkaline-earth ratio which is > 1

may be manufactured using raw materials which comprise a first batch material as described herein whilst satisfying the complex combination of requirements for manufacture of the mineral wool fibers and their raw materials.

[0005] The term wt% as used herein signifies weight %. [0006] The quantity of S1O2 in the mineral wool fibers may be > 60 wt% or > 62 wt% and/or < 72 wt%, or < 70 wt%. The quantity of AI2O3 in the mineral wool fibers may be > 1 wt% or > 2 wt% and/or < 7 wt% or < 5 wt%. The quantity of the combination of CaO and MgO in the mineral wool fibers may be >1 1 wt% or >13 wt% and/or < 22 wt% or < 20 wt%. The quantity of the combination of Na2O and K2O in the mineral wool fibers may be > 7 wt% and/or < 15 wt%, or < 12 wt% or < 10 wt%. The total iron content expressed as Fe2O3 in the mineral wool fibers may be < 1 wt% or < 0.8 wt%. The ratio of alkali/alkaline-earth, which as is conventional is expressed in terms of wt% of the oxides eg (Na2O + K2O)/(CaO and MgO) is >1 . [0007] The mineral wool fibers are preferably bio-soluble; in particular, the mineral wool fibers preferably satisfy the requirements under Note Q of EU Directive 67/548/EEC for exemption from the classification, packaging and labelling provisions of that Directive.

[0008] The method of manufacturing mineral wool fibers comprises introducing mineral batch material(s) in to a melter, melting the mineral batch material(s) to provide a melt and fiberizing the melt to form the mineral wool fibers.

[0009] The first batch material may comprise:

52 to 62 wt% S1O2, notably 52 to 56 wt% S1O2, and

16 to 25 wt% CaO, and

0 to 5 wt% MgO, and

0 to 10 wt% B2O3, notably 5 to 10 wt% B2O3, and

0 to 2 wt% of the combination of U2O + Na2O + K2O, and

0 to 1 .5 wt% TiO ₂ , and

0.005 to 1 wt% total iron expressed as Fe2O3, and

0 to 1 wt% fluoride.

[0010] The quantity of S1O2 in the first batch material may be > 52 wt% and < 56 wt%. The quantity of S1O2 in the first batch material may be > 54 wt%, > 55 wt% or > 56 wt% and/or < 61 wt%, < 60 wt%, or < 58wt%. The quantity of AI2O3 in the first batch material may be > 12.5 wt% or > 13wt% and/or < 15 wt% or < 14wt%. The quantity of CaO in the first batch material may be > 20 wt% or > 21 wt% and/or < 24.5 wt% or < 23 wt%. The quantity of MgO in the first batch material may be > 0.5 wt% or > 1 wt% and/or < 5 wt% or < 3 wt%. The quantity of total iron expressed as Fe ₂ O ₃ in the first batch material may be > 0.001 wt% or > 0.05 wt% or > 0.1 wt% and/or < 0.6 wt%, or < 0.5 wt%. The quantity of B2O3 in the first batch material may be: > 5 wt% and < 10 wt%; > 4.5 wt% and < 7.5 wt%; or > 0.25 wt% and < 3.5 wt%; or < 0.05 wt%. [001 1 ] In one embodiment, the first batch material comprises

53 to 56 wt% SiO ₂ , and

20 to 24 wt% CaO, and

0 to 2 wt% MgO, and

0.5 to 1 .8 wt% of the combination of U2O + Na2O + K2O, and

0 to 0.5 wt% TiO ₂ , and

0.005 to 0.75 wt% total iron expressed as Fe2O3.

[0012] In another embodiment, the first batch material comprises

55 to 57 wt% SiO ₂ , and

23 to 26 wt% CaO, and

1 to 4.5 wt% MgO, and

0.5 to 1 .8 wt% of the combination of U2O + Na2O + K2O, and

0.01 to 1 .5 wt% TiO ₂ , and

0.005 to 0.75 wt% total iron expressed as Fe2O3.

[0013] In a further embodiment, the first batch material comprises

58 to 62 wt% SiO ₂ , and

1 1 .5 to 14.5 wt% AI ₂ O ₃ , and

20 to 24 wt% CaO, and

1 .5 to 5 wt% MgO, and

0.5 to 1 .8 wt% of the combination of U2O + Na2O + K2O, and

0.01 to 1 .5 wt% ΤΊΟ2, and

0.005 to 0.75 wt% total iron expressed as Fe2O3. [0014] The first batch material may comprise

61 to 74 wt%, notably 63 to 72 wt% SiO ₂ , and

0 to 8 wt%, notably 0 to 6 wt% AI ₂ O ₃ , and

4 to 12 wt%, notably 6 to 10 wt% CaO, and

0 to 6 wt%, notably 0 to 4 wt% MgO, and

0 to 8 wt%, notably 0 to 6 wt% B ₂ O ₃ and

12 to 18 wt%, notably 14 to 16 wt% of the combination of Na ₂ O + K ₂ O, and 0 to 2 wt%, notably 0 to 1 wt% TiO ₂ , and

0 to 1 wt%, notably 0 to 0.5 wt% total iron expressed as Fe ₂ 03, and 0 to 1 wt%, notably 0 to 0.4 wt% fluoride.

[0015] The first batch material may comprise

70 to 77 wt%, notably 72 to 75 wt% SiO ₂₎ and

0 to 2 wt%, notably 0 to 1 wt% AI ₂ O ₃ , and

0 to 2 wt%, notably 0 to 1 wt% CaO, and

19 to 26 wt%, notably 21 to 24 wt% B ₂ O ₃ and

0 to 6 wt%, notably 0 to 4 wt% of the combination of Na ₂ O + K ₂ O, and 0 to 1 wt%, notably 0 to 0.3 wt% total iron expressed as Fe ₂ O ₃ .

[0016] The first batch material may comprise

53 to 77 wt%, notably 55 to 75 wt% SiO ₂ , and

0 to 7 wt%, notably 0 to 5 wt% AI ₂ O ₃ , and

0 to 12 wt%, notably 1 to 10 wt% CaO, and

0 to 3 wt%, notably 0 to 1 .5 wt% LiO ₂ , and

0 to 10 wt%, notably 0 to 8 wt% B ₂ O ₃ and

9 to 23 wt%, notably 1 1 to 21 wt% of the combination of Na ₂ O + K ₂ O, and 0 to 14 wt%, notably 0 to 12 wt% TiO ₂ , and

0 to 20 wt%, notably 1 to 18 wt% ZrO ₂ ,

0 to 7 wt%, notably 0 to 5 wt% total iron expressed as Fe ₂ O ₃ , and

0 to 7 wt%, notably 0 to 5 wt% fluoride.

[0017] The first batch material may comprise

52 to 62 wt%, notably 55 to 60 wt% SiO ₂₎ and

21 to 30 wt%, notably 23 to 28 wt% AI ₂ O ₃ , and

6 to 17 wt%, notably 8 to 15 wt% CaO, and 2 to 9 wt%, notably 4 to 7 wt% MgO, and

0 to 1 wt%, notably 0 to 0.35 wt% B ₂ O ₃ and

0 to 2 wt%, notably 0 to 1 wt% of the combination of Na2O + K2O, and

0 to 1 wt%, notably 0 to 0.5 wt% total iron expressed as Fe2O3, and

0 to 1 wt%, notably 0 to 0.3 wt% fluoride.

[0018] Alternatively, the first batch material may comprise

62 to 68 wt%, notably 64 to 66 wt% SiO ₂ , and

22 to 27 wt%, notably 24 to 25 wt% AI2O3, and

8 to 12 wt%, notably 9.5 to 10 wt% MgO, and

0 to 1 wt%, notably 0 to 0.2 wt% CaO, and

0 to 1 wt%, notably 0 to 0.2 wt% of the combination of Na ₂ O + K ₂ O, and

0 to 0.5 wt%, notably 0 to 0.1 wt% total iron expressed as Fe2O3.

[0019] The first batch material preferably has a composition which is significantly different from the composition of the mineral wool fibres. The first batch material may comprise:

- a quantity of S1O2 which is less than that of the mineral wool fibers, notably by at least 5 percentage points; and/or

- a quantity of AI2O3 which is greater than that of the mineral wool fibers, notably by at least 5 percentage points; and/or

- a quantity of Na2O + K2O which is less than that of the mineral wool fibers, notably by at least 4 percentage points.

[0020] The first batch material may comprise fibers, notably fibers having: an average diameter which is > 5 μιτι, > 9 μητι, > 10 μιτι or > 12 and/or < 25 μητι, < 20 μιτι or < 18 μιτι; and/or an average length which is > 2 mm, > 5 mm or > 8 mm and/or < 100 mm, < 80 mm, < 60 mm or < 50 mm. Such fibers may be produced by crushing, chopping or milling fibers having a greater length, for example fibers having a length > 30 cm or > 50 cm. The length of such fibers may be reduced for example in a wheel mill or in a hammer mill. Such lengths of fibers facilitate handling and processing. Preferably, when introduced in to the melter such fibers have an average length which is > 2mm and/or < 10 mm. Alternatively or additionally the first batch material may comprise cullet; the cullet may have a particle size such that at least 90 wt% of the cullet, preferably at least 95 wt% of the cullet has a maximum dimension < 20 mm, preferably < 15 mm and more preferably < 10 mm.

[0021 ] The first batch material may comprise, consist essentially of, or consist of scrap, notably scrap from the manufacture of mineral fibers, and particularly scrap from the manufacture of mineral fibers having a different composition and/or purpose than the mineral wool fibers being manufactured. For example, the first batch material may comprise, consist essentially of, or consist of scrap fibers, notably non woven scrap fibers, resulting from manufacture of continuous fibers. Particularly in this case, the first batch material may comprise, consist essentially of, or consist of: fibers which have broken, for example at a bushing producing continuous fibers, and/or which are unsuitable for incorporation into their originally intended product. The use of such scrap as a batch material as described herein avoids complex recycling processes and/or disposal of such scrap in landfills.

[0022] As used herein, the term "consist or consist essentially of is intended to limit the scope of a statement or claim to the specified materials or steps and those that do not materially affect the basic and novel characteristic(s) of the invention.

[0023] Particularly when in the form of fibers, the first batch material may comprise an organic coating, size or binder, for example in the form of an aqueous solution or suspension, notably comprising a starch, an oil, an emulsion, polyvinyl acetate(s), polyester(s), epoxy(s), polyurethane(s), polyvinyl pyrrolidone(s), polyvinyl alcohol(s), silane(s), organo-functional silane(s) and combinations thereof. Such an organic coating, size or binder may be present in a quantity which is > 0.5 wt% or > 1 wt% and/or < 10 wt% or 8 wt% with respect to the total weight of the first batch material. [0024] Particularly when the melter is a submerged combustion melter, the water or moisture content in the first batch material when introduced in to the melter may be > 2wt%, > 5 wt%, or > 10 wt%; and/or < 35 wt%, < 25 wt%, < 20 wt%, or < 15wt% based on the total weight of the first batch material; it may be between 10 and 25 wt%. The ability to use a batch material having a relatively high water or moisture content, notably > 10 wt% allows the use of certain available materials notable without pre-treatment to reduce water content. [0025] The first batch material may constitute: > 5 wt%, > 10 wt%, > 15 wt% or > 20 wt% and/or < 70 wt%, < 60 wt%, < 50 wt%, < 40 wt%, < 30 wt% or < 25 wt% of the total batch materials introduced in to the melter. The term "batch materials" as used herein comprises all materials, notably minerals, introduced in to the melter which provide any of the elements that will form part of the melt; the term excludes, notably: a) water (other than water of crystallization); b) organic compounds, for examples binders, which will decompose in the melter; and c) fuel and combustion gasses which serve to release energy to provide melting. It is particularly advantageous for the first batch material to constitute a significant portion of the total batch materials, notably at least 10 wt%.

[0026] Preferably, the batch materials also include a second batch material. The second batch material may comprise mineral wool fibers. Such mineral fibers may comprise

55 to 75 wt% SiO ₂ , and

5 to 20 wt% of the combination of CaO and MgO, and

5 to 20 wt% of the combination of Na2O and K2O, and

0 to 2 wt% total iron expressed as Fe2O3, and

an alkali/alkaline-earth ratio which is > 1

The quantity of S1O2 in the second batch material may be > 60 wt% or > 62 wt% and/or < 72 wt%, or < 70 wt%. The quantity of AI2O3 in the second batch material may be > 1 wt% or > 2 wt% and/or < 7 wt% or < 5 wt%. The quantity of the combination of CaO and MgO in the second batch material may be >1 1 wt% or >13 wt% and/or < 22 wt% or < 20 wt%. The quantity of the combination of Na2O and K2O in the second batch material may be > 7 wt% and/or < 15 wt%, or < 12 wt% or < 10 wt%. The total iron content expressed as Fe2O3 in the second batch material may be < 1 wt% or < 0.8 wt%.

Advantageously, the second batch material comprises a portion of the mineral wool fibers previously manufactured and recycled in the manufacturing process. Such fibers may comprise scrap, off-cuts and/or edge cuts of mineral wool insulation manufactured using the mineral wool fibers.

[0027] Particularly when in the form of fibers, the second batch material may comprise an organic coating, size or binder, for example in the form of an aqueous solution or suspension, notably comprising phenol formaldehyde, polyester(s), epoxy(s), silane(s), Maillard reactants, Maillard reactant products, organo-functional silane(s) and combinations thereof. Such an organic coating, size or binder may be present in a quantity which is > 0.5 wt% or > 0.1 wt% and/or < 10 wt% or 8 wt% with respect to the total weight of the second batch material.

[0028] The second batch material may be processed before being introduced in to the melter, for example by crushing, chopping, milling, opening out or combinations thereof. The second batch material may be processed together with the first batch material. The second batch material may be introduced in to the melter as a component of one or more briquettes, notably briquettes having one of more of the features described above other than either a) the substitution of the second batch material for the first batch material in the briquettes or b) the substitution of a combination of the first and second batch materials for the first batch material in the briquettes. The second batch material may constitute: > 5 wt%, > 10 wt%, > 15 wt%, or > 20wt% and/or < 70 wt%, < 60 wt%, < 50 wt%, < 40 wt% < 30 wt% < 25 wt% of the total batch materials introduced in to the melter.

[0029] The combination of the first and second batch materials may constitute: > 40 wt%, > 50 wt%, > 60 wt%, or > 70-% and/or < 90 wt% or < 80 wt% of the total batch materials introduced in to the melter. [0030] One or more additional batch materials may be included, notably selected from silica sand, feldspar, nepheline syenite, aplite, calcined alumina, hydrated alumina, soda-ash, limestone, dolomite, magnesite, recycled glass bottles, recycled glass sheets, borax pentahydrate, borax decahydrate and anhydrous borax and combinations thereof. [0031 ] Melting of the mineral batch materials may be carried out in a melter selected from a submerged combustion melter, a tank furnace, an electric arc furnace and a circulating furnace.

[0032] Where the melter is an electric arc furnace the mineral batch materials may be directly exposed to an electric arc so that electrical current from electrodes passes through the batch material to provoke melting.

[0033] Where the melter is a circulating furnace the method may comprise injecting particulate fuel, particulate mineral batch material(s) and primary combustion gas in to a combustion chamber which contains circulating chamber gases, thereby melting the particulate mineral batch materials to form a mineral melt and generating exhaust gases, and separating the mineral melt from the hot exhaust gases so that the hot exhaust gases pass through an outlet in the circulating combustion chamber and the mineral melt collects in a base zone.

[0034] Where the melter is a submerged combustion melter the method may comprise introducing mineral batch material(s) into a melting chamber having one or more submerged combustion burners mounted in its floor and/or wall, the submerged combustion burners melting the batch material(s) by discharging combustion products under a level of material being melted in the melter and preferably creating turbulent conditions in the melt. The melter may be a submerged combustion melter as described in any of WO 2015/014921 , WO 2015/014919, WO 2015/014920, WO 2016/120351 or WO 2016/120353, each of which is hereby incorporated by reference. [0035] Fiberizing the melt to form the mineral wool fibers may comprise fiberizing the melt using an internal spinner. When using an internal spinner, the melt is introduced into the interior of an internal spinner rotating about a substantially vertical axis, travels towards the interior surface of a peripheral wall of the spinner, passes through orifices in the peripheral wall of the spinner to form melt streams which are attenuated by blast air passing along or adjacent to the external side of the peripheral wall of the spinner to form mineral fibers.

[0036] According to a further aspect the present invention provides a method of manufacturing a mineral fiber thermal insulation product comprising the sequential steps of:

a) making mineral wool fibers from a melt, notably according to one or more of the aspects described herein;

b) spraying a binder solution, notably an aqueous binder solution, on to the mineral fibers;

c) collecting the mineral fibers to which the binder solution has been applied to form a blanket of mineral fibers; and

d) curing the binder by passing the blanket of mineral fibers through a curing oven. [0037] Prior to curing, the mineral fibers to which the binder solution has been applied may be collected to form a primary blanket of mineral fibers which is subsequently folded over itself, for example using a pendulum mechanism, to produce a secondary blanket comprising superimposed layers of the primary blanket.

[0038] Wash water may be sprayed on to mineral fibers between their formation and their collection to form a blanket, at least a part of the wash water having been sprayed on mineral fibers and subsequently returned to a wash water system to be reused as wash water. The binder solution may comprise wash water. The solids content of the binder solution applied to the mineral fibers may be > 10 wt% or > 12 wt% and/or < 20 wt% or < 18 wt%. The term "dry weight of the binder solution" as used herein means the weight of all components of the binder solution other than any water that is present (whether in the form of liquid water or in the form of water of crystallization). [0039] Preferably the binder solution does not comprise any added formaldehyde. It may be "substantially formaldehyde free", that is to say that it liberates less than 5 ppm formaldehyde as a result of drying and/or curing (or appropriate tests simulating drying and/or curing); more preferably it is "formaldehyde free", that is to say that it liberates less than 1 ppm formaldehyde in such conditions. [0040] Alternatively, the binder solution may be a phenol formaldehyde binder solution, notably a urea extended phenol formaldehyde binder solution.

[0041 ] The binder solution may comprise reducing sugar(s), notably in a quantity which is a) > 30%, > 40%, > 50%, > 60%, > 70% or > 80% of the dry weight of the binder solution and/or b) < 97% or < 95 % of the dry weight of the binder solution. The reducing sugar reactant(s) may be selected from one or more: monosaccharide, monosaccharide in aldose or ketose form, disaccharide, polysaccharide, triose, tetrose, pentose, xylose, hexose, dextrose, fructose, heptose, high fructose corn syrup (HFCS), molasses, starch hydrolysate, cellulose hydrolysates, and mixtures thereof. The reducing sugar reactant(s) may have a dextrose equivalent of at least about 50, at least about 60, at least about 70, at least about 80 or at least about 90. [0042] The binder solution may comprise nitrogen-containing reactant(s), notably in a quantity which is a) > 2.5%, > 5% or > 10% of the dry weight of the binder solution and/or b) < 50%, < 40%, < 30% or < 25 % of the dry weight of the binder solution. The nitrogen-containing reactant(s) may be selected from one or more of: NH3, inorganic amine, organic amine comprising at least one primary amine group and/or salts thereof, inorganic and organic ammonium salt, ammonium sulfate, ammonium phosphate, diammonium phosphate, ammonium citrate, diamine, polyamine, primary polyamine (ie an organic compound having two or more primary amine groups (-NH2)), 1 ,6-diaminohexane (hexamethylenediamine, HMDA), 1 ,5- diamino-2-methylpentane (2-methyl-pentamethylenediamine).

[0043] The binder solution may comprise, by dry weight, (i) > 25%, > 40%, > 50% or > 60% of the combination of: (a) reducing sugar reactant(s) and nitrogen- containing reactant(s) and/or (b) curable reaction product(s) of reducing sugar reactant(s) and nitrogen-containing reactant(s). The nitrogen-containing reactant(s) and the reducing sugar reactant(s) (or their reaction product(s)) may be Maillard reactants that react to form Maillard reaction products, notably melanoidins when cured. Curing of the binder composition may comprise or consist essentially of Maillard reaction(s). The cured binder composition may comprise melanoidin- containing and/or nitrogenous-containing polymer(s); The binder composition may comprise a binder composition as described in any of WO 2007/014236, WO 2009/019232, WO 2009/019235, WO 201 1/138458, WO 201 1/138459 or WO 2013/150123, each of which is hereby incorporated by reference. The binder composition may include ester and/or polyester compounds. The cured binder may comprise greater than 2% and/or less than 8% nitrogen by mass as determined by elemental analysis

[0044] The curing temperature and time for the blanket of mineral wool fibers may be selected as a function of the product density and/or thickness. The curing oven may have a plurality of heating zones having temperatures within the range 200 °C to 350 °C (typically 230°C to 300 °C). A thin, low density product (12 kg/m ³ or less) may be cured by passing through the curing oven in as little as 20 seconds; a thick, high density product (80 kg/m ³ or more) may require a passage of 15 minutes or more in the curing oven. The blanket of mineral wool fibers may reach a temperature in the range 180 °C - 220 °C during the curing process. The duration of passage of the blanket through the curing oven may be > 0.5 minutes, > 1 minute, > 2 minutes, > 5 minutes or > 10 minutes and/or < 50 minutes, < 40 minutes or < 30 minutes.

[0045] The quantity of cured binder in the cured blanket of mineral wool fibers may be > 1 %, > 2%, > 2.5%, > 3%, > 3.5% or > 4% and/or < 10% or < 8%. This may be measured by loss on ignition (LOI).

[0046] The cured blanket of mineral wool fibers may have one or more of the following features:

- a density greater than 5, 10, 15, 20 or 25 kg/m ³ and/or less than 120, 100 or 80 kg/m ³ ;

- a thermal conductivity λ measured at 10°C which is < 40 mW/m.K and/or > 20 mW/m.K, notably when measured in accordance with ISO 8301 ;

- comprise less than 99% by weight and/or more than 80% by weight mineral fibers; -a thickness of greater than 10 mm, 15mm or 20 mm and/or less than 400mm, 350 mm or 300 mm;

- a length which is > 90cm, >120 cm, >150 cm and/or < 220 cm or <180 cm;

- a width which is >50 cm, >70 cm and/or <100 cm or <90 cm.

[0047] Embodiments of the invention will now be described by way of example only. The following examples a, b, c, d, e and f show:

i) the composition of a mineral wool fibers that may be produced (Table 1 );

ii) batch materials and their quantities that may be used to make the glass fiber composition of each of examples a to f (Table 2);

iii) the composition of the scrap fibers (Batch material 1 ) used for each example (Table 3); and

iv) the composition of the other batch materials used for each example (Table 4). [0048] Table 1 : Composition of mineral wool fibers manufactured in wt%

[0049] Table 2: batch materials used in wt% Batch Batch Batch Batch Batch

material 1 material 2 material 3 material 4 material 5

Scrap fibers Silica sand Soda ash Borax Dolomite

Ex a 26.53 57.47 9.73 4.42 1.86

Ex b 37.59 42.96 11.82 5.37 2.26

Ex c 33.71 44.94 12.36 1.12 7.87

Ex d 32.26 43.01 11.83 5.38 7.53

Ex e 10.19 55.56 18.52 9.26 6.48

Ex f 11.22 61.22 10.20 10.20 7.14

[0050] The quantity of batch material 1 (scrap fibers) in Table 2 is the quantity of the mineral portion of the fibers once any organic binder has been removed by decomposition.

[0051 ] Table 3: Composition of batch material 1 (Scrap fibers) in wt%

[0052] Table 4: composition of other batch materials in wt%

[0053] The quantities in Table 4 are expressed when fully calcined; the loss represents primarily decarboxylation of calcinates and loss of water of crystallization.

[0054] As can be seen in the tables, the first batch material may have a composition significantly different from the composition of the melt or mineral fibers produced.