SK6895A3 - Refractory periclase-forsterite-spinel building material - Google Patents

Abstract

In the present invention there is disclosed a refractory periclase-forsterite-spinel building material formed by a mixture containing 2 to 11 percent by weight of Ali2Oi3, further 2 to 13 percent by weight of SiOi2 and the balance being MgO, whereby this mixture is defined by a mutual ratio of the two basic materials ensuring a desired composition of the mixture, and namely 5 to 40 percent by weight of a sintered material containing 19 to 27 percent by weight of Ali2Oi3, 22 to 32 percent by weight of SiOi2, 44 to 55 percent by weight of MgO and 60 to 95 percent by weight of sintered magnesia of extreme purity containing at least 97 percent by weight of MgO.

Description

Disadvantages of the current state and increased performance properties of refractory pcriclas-forsterito-spinelitic building materials are solved by the invention, which is concerned with the formation of a chemical composition of 2 to 11 percent by weight of Al2O3 and 2 to 13 percent by weight of SiO2. MyO content, which is given by the ratio of two basic materials, which ensure the desired composition of the mixture, namely the sintered material of approximately eutectic composition of the minerals forsterite-spinel-periclase of the ternary diagram of Al2O3-SiOg-MgO and clinker-free iron magnesite.

Production of sintered material of eutectic composition for example, from high purity kaolinite having an AlgO? content of from 30.5 to 42 percent by weight, SiO? Qd 43.0 to 47.0 weight percent and with very low alkali content, up to 1.5 weight percent.

The kaolinite of said composition is ground to a fineness of at least 90 weight percent below 0.06 min and mixed with either caustic pure magnesite or pure sintered magnesite clinker containing MgO of at least 97 weight percent ground to a fineness of C below 0.06 mm at least 90 weight percent. The most preferred mixing ratio of kaolinite and magnesium material is 1.2: 1 and 1: 1. This ratio ensures the approximately eutectic composition of the mixture, with the said chemical composition of the mixed components. Mixing is carried out in a high-speed countercurrent mixer with the addition of 1 to 2% by weight of anhydrous substance in the case of the use of caustic magnesite and 1 to 2% by weight of a 20 ° 0e suifite liquor. When mixed with sintered magnesite clinker, only the sulphite liquor is added. Stirring takes 15 to 20 minutes. The material rejected in this way is pressed into several pieces for firing by means of several pressings and venting at 60 to 00 MPa. The firing is carried out, for example, in tunnel or car-chambers as well as heat of 1700 ° C for 3 hours. The growth temperature is 70 to 90 C ^for one hour in a continuous curve. The thus obtained fired compacts are crushed to a grain size below 3 inm.

The obtained sintered material. has the following properties:

density min. 2.5 g / cm 2 absorbency max. 13% apparent porosity max. 25 h

Spinelitic-fursteritic double-clinker, with a low periclase content, can be used in admixture with pure inorganic clinker for the production of special refractory building materials or ramming and inserting materials and mortars. In these materials it is used as the binding material of the forming composition. By using this special dual-clinker, high-quality building materials are obtained, the advantage of which is low thermal conductivity, high resistance to temperature changes, resistance to cement clinker and therefore can be used in cement rotary kilns. Furthermore, they are characterized by high density and low porosity, which allows their use in steel aggregates and laboratory stoves.

Example

Model building materials from base materials according to Table 1 were produced.

Chemical composition and properties of basic materials used

Table 1

unit. N The KM SFDS SiO ₂ % 0.04 44.3 0.02 21.2 ^A1 ° 2 % - 39.15 0.01 19:45 ^Fe 2 ° 3 % 0.12 0.15 0.03 - CaO % 0.15 0.35 0.09 - MgO % 99.5 0.00 90.6 54.6 loss on ignition % - 14.0 0.63 - bulk density g.cm “ ⁵ 3.45 - - 2.50

N - low iron ferrous magnesium

K - kaolinite

KM - low-ferrous caustic magnesite SFDS - spinolithic-forsterite double sinter prepared from kaolinite and caustic magnesite

The forming mixtures were prepared in the kits according to Table 2. 1-2% by weight of liquid sulite leachate of density 23 ^u 0e was used as an additive. The moisture of the molding composition was 1.3 to 2.0 weight percent. The mixture was stirred in a countercurrent mixer after oak for 15 minutes.

Composition of curing mixtures / masses. % /

Table 2

granularity SFDS model building material model building II The 50 - - KM 50 - - N 1-3 mm - 35 45 N 0-1 mm - 10 10 N -0.09 mm - 30 30 SFDS 0-3 mm - 25 15

N - low iron ferrous magnesium

K - kaolinite

KM - low-ferrous caustic magnesite SFDS - spinelitic-forsterite double sinter prepared from kaolinite and caustic magnesite

The building materials were pressed under pressure of 100 MPa to moldings of dimensions 250x125x65 mm. The compacts were fired in a box furnace at 1700 C and hold ^for 3 hours at this temperature. The properties of model building materials are shown in Table 3.

Physical and mechanical properties of periclase-forsteritospinelitic building materials

T a b u t k a 3

unit. SPDF model building material model building II bulk density g.cm ” ³ 2.50 2.07 2.84 apparent porosity% 22.9 11.97 15.44 compressive strength MPa - min. 45 min. 38 thermal conductivity W / m / kJ at 1100 ° C - 1.2536 1.5300 absorbability % M 4.15 5.45 Spaling cycles - 100 100 MgO flocking. ^ 51,03 35.36 86.67 λι ₂ ο ₃ hmôt Λ 21.6 6.49 5.82 SiO ₂ wt.% of 24.45 6.87 6.24 CaO wt.% - 0.21 0.22 ^Fe 2 ° 3 hmôt Λ - 0.27 0.25

Industrial usability

The refractory periclase-forsterito-aggregate construction material according to the invention is intended for use in cement kilns, steel aggregates and laboratory ovens. Using the appropriate granulometric composition and known additives, it is envisaged to use a molding composition for the production of ramming, gunning or casting compositions and mortars.

Claims (1)

Refractory periclase-forsterito-spinelite construction material, characterized in that the chemical composition of the forming mixture is 2 to 11% by weight Al 2 O 3, 2 to 13% by weight SiO 2, the rest being MgO, the mixture being a ratio of two basic materials providing the desired composition of the mixture, namely 5 to 40 weight percent sintered material containing 19 to 27 weight percent AlgOp 22 to 32 weight percent SiOgj 44 to 55 weight percent MgO and 60 to 95 weight percent sintered high purity magnesia content of at least 97% MgO by weight.