DD237434A3 - METHOD FOR PRODUCING TEMPERATURE-RESISTANT ROCK FIBERS - Google Patents

Abstract

The invention relates to a process for the production of inorganic fiber products for thermal insulation purposes, usable up to application limit temperatures (AGT) of min. 750C to about max. 900C or for the substitution of asbestos in certain asbestos-containing products, preferably with thermal stress. The aim of the invention is to produce inorganic fiber products cost-effectively, which under continuous use in the o. A. AGT does not show a deterioration in the performance characteristics - in particular the thermal insulation - by sintering / softening or crumbling. According to the invention, the high temperature stability of this fiber product is achieved by using raw materials containing principally the mineral "chlorite" to produce the melt and the fibers to be produced therefrom. These guarantee an extremely high dispersion of the Fe2 and Fe3 ions in the melt and in the fiberglass. The statistical distribution and coordination of the Fe2, Fe3, Mg2 and Al3 ions in the chlorite-containing raw materials, in the melt and in the fiberglass, which is obviously extremely favorable for nucleation, leads to a regular, very fine re-heating of the fibers early on Volume crystallization with the effect of stiffening and elevation through the crystal reinforcement and increase in temperature stability.

Description

Field of application of the invention

The invention relates to a process for the production of inorganic fiber products for thermal insulation purposes, usable up to application limit temperatures (AGT) of at least 750 to about max. 900 ° C, depending on their assembly, the type of installation and their complex thermal / chemical / mechanical stress during the furnace journey or for the substitution of asbestos in certain asbestos-containing products, preferably with thermal stress.

Characteristic of the known technical solutions

For energy-intensive Wärmeaniageh of all kinds come next to conventional heavy refractory construction and thermal insulation materials for highly effective modern partial or full-fiber applications increasingly the following fiber products are used:

- Refractory fibers of various types with AGT a 1 100 ⁰ C, which are limited because of their high price, ie can be used on the fire side.

- Mineral or slag or rock fibers, which are produced cheaply as mass fibers with productive processes and because of their poor properties (fluctuating stock, heterogeneous microstructure and .ungsten sintering / crystallization behavior of the fiber glass) only up to AGT of about 200 to max. about 550 ⁰ C can be used.

Due to the lack of low-cost fiber insulation for the medium temperature range, modern all-fiber applications have hitherto been the case. on the combination refractory fibers / mineral wool with AGT max. about 55O ⁰ C instructed, which made the increased use of very expensive refractory fiber products for the medium temperature range up to about Schichtganztemperaturen of about 550 ⁰ C required. For economic reasons, therefore, the aim is to develop low-cost fiber products for medium Temperatürbereich to about 800 ⁰ C AGT to reduce the use of expensive refractory products or combinations of Faserdämmstofferi: refractory fibers / temperature resistant rock fibers with AGT about 800 ° C / mineral wool to use and to reduce the delivery costs to economically justifiable relations with the extensive application of state-of-the-art, highly effective full-fiber delivery systems.

- Rock fibers with AGT of about 800 ⁰ C.

, There are z. Z. international only a few fiber products known for the said medium temperature range, which are usually made of conventional melt raw materials and conventional processes for the production of bulk fibers for sound and thermal insulation purposes.

The reasons for the relatively favorable temperature stability of a few of these fiber products are presumably given by the lower FeO, higher CaO + MgO or .AI ₂ O ₃ contents and / or a more homogeneous fiber glass with a relatively favorable microstructure. The current level of knowledge is insufficient.

Object of the invention

The aim of the invention is to produce inorganic fiber products cost-effective, which are temperature resistant during installation behind refractory construction or thermal insulation or Direktkbntakt with the hot gases of thermal systems of various kinds to about 800 ⁰ C AGT, ie no unreasonable sintering or softening and no Zerrieseln by thermal aging or oxidation of FeO or by inappropriate crystallization of fiberglass show. This means that in continuous use form and existing fiber structure of the thermal insulation material must be largely retained, so that no deterioration of the performance characteristics - in particular the thermal insulation - can occur.

The application of loose fibers can be done directly for stuffing or spray insulation without further packaging. When used as plates, mats or module a corresponding assembly using suitable binders according to known methods is required.

Furthermore, it is the object of the invention to replace the proposed fibers asbestos in certain asbestos-containing products with preferably thermal stress up to about 800 ⁰ C but also with combined thermal / chemical / mechanical stress except in extremely alkaline matrix.

the essence of the invention

According to the invention, the high temperature resistance of this fiber product is achieved by mainly using the raw material containing minerals to produce the melt and fibers to be produced therefrom Depending on the atmosphere of the fines, iron-rich rock glasses with FeO / FeO + Fe ₂ O ₃ contents are formed in the ratios of about 80% 0%.

The principle of the invention is based on the structure of the chlorite minerals. In these, 3-layer packets (talc or phyllite layers) and additional octahedral layers (brucite or hydrargillite) alternate. The chlorites form highly lorhous mixtures, whereby in the brucite layer a part of the Mg is replaced by Fe ²⁺ (and Al) and in the phyllite layers a part of the Al is isomorphously replaced by Fe and Mg. Accordingly, the proposed chlorite raw materials guarantee your extremely high dispersion of Fe ² * - and Fe ³⁺ ions in the melt and in the fiber glass and in conjunction sinem suitable oxidizing melting regime also an optimum ratio of Fe ²⁺ / Fe ^3+. The extremely favorable statistical distribution and coordination of the abovementioned ions in the chlorite-containing raw materials, in the melt and in the fiberglass, is probably due to mixed crystals (spinels) as an intermediate, during the reheating of the fibers to an early onset even before the start of sintering , finest volume crystallization. This has the effect of blocking and delaying fiber sintering and, among other things, by the stiffening effect of the crystal reinforcement, the 3Strebte increase the temperature resistance of the fiber products. The formation of extremely fine crystals with nm diameter is particularly important, since coarser crystal diameters in the μΓΤΐ range would destroy the fibers of a few knives.

• found that the o. G. uniform and very fine volume crystallization only occurs in the nm range if the fiberglass has high nucleation concentration (formation rate), which could only be achieved with the higher-chlorite raw materials.

Furthermore, it has been found that a FeO / FeO + Fe ₂ O ₃ ratio of 20 to 50% in the fiber grade leads to optimum crystallization in the. Meaning, ie leads to particularly high Keimkonzentration- or -bildungsgeschwindigkeit and to particularly small crystals. 3 always resulted in a remarkably gentle stress on the fiberglass during reheating or in the oxidation of the FeO to D ₃ . The described optimal crystallization always occurred with neutral to oxidizing melt. It was also possible to establish that under these conditions of melting no thermal aging occurred which, like the above causes, could contribute to the crumbling of the fiber products even in the temperature range of about 200-500 ° C., owing to the considerable hardness differences in diabase rocks occurring minerals, it comes during the breaking process in ikorn (crushed sand) and especially in the finest grain or dusts that occur in the dedusting of basschotter / 'split production, to a significant enrichment of minerals of low hardness - especially of orit with hardness about 2, 5 - and on the other hand to a rigorous reduction of minerals of greater hardness such as quartz, feldspar

Therefore crushing sand and especially the dusts not only have a qualitatively and ntitatively fundamentally different mineral structure compared to diabase rocks, but are also characterized by much smaller variations of the mineral contents, especially of the chiorite. On the other hand, in the case of basalt rocks - for example, in gravel size - genetically determined from the most diverse deposits with large fluctuations in the mineral content can be said.

Grain fineness of the dusts (about> 70% g 0.063 mm) also promotes the formation of an extremely honiogenen fiberglass and ar optimal crystallization during reheating, which is likely to explain the always maximum experimental results of the fibers preferably made of dusts.

From the above, it can be deduced that the higher chlorite contents of the proposed grain fineness and consistency of the diabase dust preferably used in the invention in conjunction with a prescribed imelzverfahren to achieve optimum FeO / FeO + Fe ₂ O ₃ ratios and ultra-fine volume crystallization in nm range represent the most important principles and prerequisites for the technically exploitable active principle for the production of temperature-resistant stone fibers.

¹ with a chemical composition of

sfiihrungsbeispiel Kornfeinl becomes diabase dust ( 38.2% SiO ₂ 14.2% Al ₂ O ₃ 14.5% 'Fe ₂ O _3ges 3.7% TiO ₂ 8.5% CaO 7.5% MgO 2.9% KjO + Na ₂ O 0.2% ·· MnO 0.4% S as SO ₃ 8.4% GV

a mineral population of

Chiorit approximately 40-45% hornblende approximately 5% quartz 5% plagioclase approximately 10-15% calcite 5%

swellable

Minerals 5%

Pyroxene 10%

and house pellets having a composition of about 38% SiO ₂ , 9.3% Al ₂ O ₃ , 0.5% Fe ₂ O _3g e _S , 37.3% CaO, 8.6% MgO, 1.8% Na ₂ O + K ₂ O in the ratio 80: 20% mixed and pelletized. The pellets with diameters of 15-35 mm were melted in a shaft furnace at temperatures of about 1 430 ° C oxidizing.

The melt-blown fiber products (average fiber diameter about 4-5 μπη) had the following chemical composition:

SiO ₂ 40.9% Al ₂ O ₃ 14.7% FeO 5.3% Fe ₂ O ₃ 8.3% CaO 18.2% MgO 6.8% K ₂ O + Na ₂ O 3.3% MnO 0.2% TiO ₂ 3.0% S as SO ₃ 0.1%

In laborativer and industrial long-term testing of the fiber products (loose fibers and sheets) according to the invention proved resistant to temperatures up to about 800-850 ⁰ C.

Claims (5)

Claim: 1. A process for the production of rock fibers for thermal or thermal / chemical / mechanical stress for use temperatures of 750-900 ⁰ C by melting and shredding chlorite raw materials, characterized in that raw materials are used with chlorite contents of 35-45 wt .-% and the Mass ratio of divalent to trivalent iron is adjusted so that in the fiberglass 20-50 Ma .-% FeO, based on the content of FeO + Fe ₂ O ₃ , are present. 2. The method according to item 1, characterized in that preferably used as fusing raw materials or briquetted dust from the dedusting of the Diabasschotter- and -splittproduktion, but also there incurred crushing sand and rocks from geological formations. - 3. The method according to points 1 and 2, characterized in that the melt of almost neutral, z. B. in electric furnace, until mainly oxidizing, z. B. in the tub or shaft furnace, is performed. 4.Verfahren according to points 1 to 3, characterized in that the basic ingredients are added to the chlorite-containing raw materials in compliance with the lower limit of the chlorite content basic raw materials such as Hüttenbims and cement dust. 5.Verfahren according to the points 1 to 4, characterized in that in the case of the use of Diabasstäuben and basic additives, these substances are mixed before the Stückigmachung.