SU1281550A1 - Method of manufacturing magnesia articles - Google Patents

Abstract

The invention relates to the refractory industry and can be used in the manufacture of sintered refractories for lining thermal units of ferrous and non-ferrous metallurgy. The aim of the invention is to reduce heat consumption while reducing the firing temperature of products to 1300 1400 ° C while maintaining high strength. The method includes the operations of mixing the ground component with the main refractory material, pressing and firing. A new method is the mechanical activation of a fine-milled component in a high-speed flow created by a vortex or planetary mill for 30-45 MHHj, resulting in a high degree of sintering of refractory products at lower firing temperatures. The mechanical activation of the particles can be carried out both after grinding to a finely ground component in the vibratory mill, and simultaneously with the grinding, if it is produced in a vortex or planetary mill. 1 hp f-ly, 1 tab. i (L

Description

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IE; Britning refers to the refractory industry and can be used in the manufacture of calcined refractories for lining thermal units of ferrous or non-ferrous metallurgy.

The purpose of the invention is to reduce the heat consumption for firing.

The activation effect is based on the fact that with a large dynamic load on the grains, significant physicochemical changes occur in their surface structure, the concentration of point defects increases, the dislocation density increases, the crystal lattice undergoes large deformations and loosens. As a result, -chemical properties of such periclase, in particular, the degree of hydration increases. The activation effect can be established by broadening the diffraction maxima of the X-ray reflection. Mechanical activation reduces the sintering temperature of refractory products.

The mechanically activated periclase loses its active properties with time, since the air is undergoing enhanced hydration of fine-grained activated material; therefore, activation is performed immediately before the components are mixed. Storage of activated mat-. Riala can be carried out in a closed container 12-20 hours

The activation can be carried out simultaneously with the grinding, if the grinding is carried out in the specified energy-stressed grinding, as they provide grinding to the ir fraction of 0.063 mm, adopted in ceramic technology for the fine component.

The particle movement speed should be at least 70 m / s, since at lower speeds the activation is weak and the activation time must be increased to 5-7 hours, which is technologically unjustified. The upper limit of 200 m / s is established from the capabilities of the existing equipment.

When using existing milling equipment for activation of particles, for example, a vortex mill, reliably operating at linear speeds of movement of organs of 70-100 m / s, the grinding time must be at least 30 minutes. With less time effect

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activation is weak and the strength of the products is low. With an increase in activation time in excess of 45 minutes, the activity of the powder for sintering does not increase and there is no longer any increase in strength, and the productivity of the equipment decreases and the cost of its operation increases.

When the firing temperature of products is less than 1300 s, the strength of the products is low, with an increase in the firing temperature, it almost does not increase, and the heat consumption for firing of products increases unreasonably.

The use of activated periclase fine milled component is effective for improving sintering not only for purely periclase masses, but also for the masses of chromitopericlase and periclase-carbon compositions. The method of manufacturing refractory products is carried out as follows.

To obtain the masses of the periclase composition, the melted periclase is ground and dispersed into fractions of 3-1 and 1-0 mm. A portion of the fused periclase of the 1-0 mm fraction is crushed in a vibrating mill to a fraction of 0.063 mm, and then further subjected to mechanical activation for 30-45 minutes in a vortex-type mill. To obtain a mass with a finely ground component activated during the grinding process, the melted periclase of a fraction of 1-0 mm is fed into a vortex mill and crushed for 30-45 minutes.

Granular powders are loaded into the mixer and a sulphite-yeast brewing solution (BDS) is poured with a density of at least 1.2 g / cm at 30-35 ° C to a moisture content of 3-5%, the mixture is stirred for 4-5 minutes, then the activated fine grinder is fed Add 45 to the SDB to a moisture content of 5–8%, and stirring continues for another 5–6 minutes.

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To obtain the masses of the chromite-periclase composition, it is prepared melted

50 l of romitoperiklaz of a fraction of 1–0 mm, periclazochromite of a fraction of 3–1 mm, and a fine grind component of combining grinding and particle activation. The mixture of powders is carried out similarly

55 previous.

In order to obtain masses of periclase-carbonaceous composition, periclase powders of fractions 3-1 mm and 1-0 mm are loaded into the mixer, 30 are mixed, to prepare masses of chromite-periclase composition, fused

50 l of romitoperiklaz of a fraction of 1–0 mm, periclazochromite of a fraction of 3–1 mm, and a fine grind component of combining grinding and particle activation. The mixture of powders is carried out similarly

55 previous.

In order to obtain masses of periclase-carbon composition, periclase powders of fractions 3-1 mm and 1-0 mm are loaded into the mixer, 3031281550 are mixed

40 seconds, the SDB is poured to a moisture content of 3-5%, the mixture is stirred for 2-3 minutes, then flake graphite, silicon carbide of a fraction of 0.5 mm, finely ground activated periclase is added, the mixture is stirred, the moisture content is adjusted to 6-7% by adding SDB, and mixing continues for 3 more. 5 minutes.

From the obtained masses, the products are pressed at a pressure of 100-150 MPa, dried at 140-160 ° C and burned at 1300-1400 C with a shutter speed of at least 2 hours.

According to the proposed method, samples with a diameter of 36 mm and a height of 40 mm of periclase, chromite-periclase and periclase-carbon composition are prepared. Mechanical activation is carried out in a vortex type mill.

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The table shows the composition and properties of the manufactured products.

Analysis of the table shows that the optimal firing temperature, which ensures a sufficiently high strength of the products, is 1300-1 400 s with an activation time of particles of 30-45 minutes.

The decrease in the firing temperature of refractories, achieved due to the mechanical activation of the fine-milled component, reduces the heat energy consumption during the operation of tunnel kilns by 20-30%, at which the firing temperature is 1730-1750 C.

Claims (2)

1. A method of making magnesia products by mixing finely. For comparison, they are also prepared with a ground component of 20% with a main fire. -five ten 15 the samples from the non-activated fine-grained component (fraction 0.063 mm) obtained by a known technology. The products are subjected to tests for strength, heat resistance by the heating-to-cooling cycle in water, and their porosity is also determined. The main benchmark for the degree of sintering is the compressive strength. The proposed method has no significant effect on other physico-ceramic characteristics of refractories and can be considered identical for the proposed and known methods. Composition 1 1. Periclase fractions, mm 3-1 1-0 Periclase activated with a fraction of 0.063 mm resistant material, pressing and firing products, characterized in that, in order to reduce heat consumption in firing, finely ground component is subjected to mechanical activation prior to mixing by impacting particles in a high-speed flow for 30-45 minutes, and firing products at 1300 -1400 C. 2. The method of claim 1, wherein the mechanical activation is carried out in a vortex or planetary mill at the same time as grinding. 1300 16-18 42.0- 43.0 4-5 55 thirty Activation time i 30 min . , , Composition 1 1 40 min Composition 1 1 45 min Periclase fractions, mm 3-115 1.0, 55 0.063 .30 (not activated) Periclazochromite fraction 3-1 mm15 Hromitoper.iklaz fraction 1-0 mm55 Periclase activated fraction of 0.063 mm30  v 30 min Periclazochromite fractions 1-O mm15 Chromitopericlase fractions 1-0 mm55 Periclase fraction 0.063 mm 30 (non-activated) Periclase fractions 3-1 mm 15 1-0 mm 40 Flake graphite5 Silicon Carbide Fractions 0.5 - O mm5 Periclase activated fraction 0,063 mm35  v 30 min BUT Table continuation 16-18 44.0 /; 16-18 45.0 4-5 4-5 1200 27 11.0 1400 17 41.0 7-8 1400 nineteen 24.0 7-f 1300 20 35.0 ten