SU870381A1 - Charge for making refractory materials - Google Patents

Description

one

The invention relates to the manufacture of basic refractories.

A known composition for the manufacture of refractories, consisting of grains of periclase, refractory chromite and previously reacted grains of chrome spinelide 1 1. Refractories of this composition have a high chemical resistance, building strength, low shrinkage during firing and increased resistance to thermal shocks.

However, with an increase in the temperature of their use to 1400-1570 ° C, the number of thermal cycles decreases due to the presence of periclase grains in the mixture, which have a high thermal expansion coefficient. When the temperature rises to 1700s, their strength decreases.

The closest to the technical essence of the invention is the charge for the manufacture of refractories, containing components, wt.%: Chromite ore 8-40, binding additive 3-5, magnesite-chromite clinker else Z. The disadvantage of this mixture is low strength at high temperatures (1400-1700 s), destruction at cyclical fluctuations of temperature, tours in the range of 1400-1570 C and high additional shrinkage at a temperature of 1750 s.

These drawbacks are a consequence of the use in the batch of low-active sintering of magnesite-chromite clinker.

The purpose of the invention is to reduce the additional shrinkage of fire stops at a temperature of 1750 ° C, increase the mechanical strength in the range of 1400-1700s and resistance to cyclical temperature fluctuations in the range of 1400-1570 ° C.

15

The goal is achieved by the fact that the charge, including magnesia-chromite clinker of a fraction of 1-3 mm, chromite ore fraction less than 0.06 mm and a binding additive, additionally contains a magnneite-chromite product of pulverion from rotating kilns of a fraction less than 0.06 mm with the following ratio of components, wt.%:

Magnesite Chromite

25

clinker fraction

1-3 mm55-68

Chromite ore

fraction less

0.06 mm 12-25

Binding Supplement 2.5-3

thirty

Magnesite-chromite product of dusting from rotary kilns fraction less than 0.06 mm, 10-20 When calcined, such a mixture is actively sintered with the formation of a solid solution of spinelide in periclase and tumors of secondary magnesian-chromic spinel containing AI.B the resulting material is thermal physical phase constants in granular on the substrate and the product, the interactions of the components of the finely dispersed part of the charge are close, which provides enhanced resistance to cyclic heat changes in the especially dangerous temperature range of 1400-1570s. Mutual distribution of phases of the same type in the dispersed component of the charge and on contact with the granular component, the extensive development of intercrystalline contacts provides an increase in the penetration of products at high temperatures of 1400-1700 C. The addition of a magnesite-chromite product of pulpless in the amount of less than 10% does not provide the specified sintering and leads to a decrease in strength properties (especially at a temperature of 1600 and). The addition of more than 20% leads to a sharp increase in additional shrinkage, as well as to a decrease in the strength properties at high temperatures.

The choice of the grain composition of the charge is determined by the need to obtain the most dense packing of the grains, to obtain a densely baked crock and the required phase composition, which is achieved by using finely dispersed chromite ore in the mixture and the sintering product of rotary kilns active for sintering.

When granular magnesite-chromite clinker with a particle size of more than 3 mm is used in the charge, the interaction area with the finely dispersed part of the charge decreases, and the phase formation processes are less active.

The choice of the particle size of the mill part of the mixture less than 0.06 mm is due to the need for a more complete process of sintering with the formation of a solid solution of spineldi in periclase and secondary magnesia-chromic spinel. s

Three mixtures were prepared for the manufacture of refractories.

Table 1 shows the compositions of the proposed charge.

Table 1

Components

The content of components, wt.%, In the charge

HIE

67

62

57 20

20

20 t

20 3

15 10

3

An aqueous solution of sulfite-alcohol bards with a density of 1.25 g / cm was used as a binding additive. The mixture was thoroughly mixed in runner mixers. The products were pressed on a hydraulic press with a specific pressing pressure of 1300 kgf / cm. Calcination was carried out in a tunnel kiln with aging; oh 4 hours

Table 2 shows the indicators of the properties of the products obtained from the compositions of the proposed and known mixture, after calcination and at.

Claims (2)

Table 2 The use of precursors with the charge for the manufacture of refractories allowed to improve the operational properties of refractories, which determine the stability of products at high temperatures under the action. external loads and cyclical temperature fluctuations. In addition, it was possible to efficiently use both the main and the by-products of the production of baked magnesite-chromite clinker. Claims for the manufacture of refractories, comprising magnesia-chromite clinker of a fraction of 1-3 mm, chromite ore fraction less than 0.06 mm and a binder additive, characterized in that, in order to reduce additional shrinkage at a temperature of increasing mechanical strength in the interval of 1400 -1700 s and resistance to cyclic temperature fluctuations in the range of 1400-1570С, it additionally contains Plesunos magnesite-chromite product from rotary kilns of fraction less than 0.06 mm in the following ratio of components, wt.%: agnesite-chromite clinker fractions 1-3 mm55-68 Chromite ore fraction less than 0.06 mm12-25 Binding additive 2.5-3 Magnesite-chromite product of pulverizer from rotary kilns fraction less than 0.06 mm. 10-20 Sources of information taken into account in the examination 1. US Patent No. 3798042, cl. From 04 to 35/24, 35/42, published. 03/19/74. ; 2. USSR author's certificate number 534441, cl. From 04 To 35/02, 1977.