CS268296B1 - Lining, hearth furnace transitions · - Google Patents

Abstract

The linings of the transitions of the blast furnaces are made of two structurally different types of fused magnesite-chromium stones with porosity of 11 and 16% by volume, respectively 16 and 21% by volume. Both types of stones contain 8 and 20.5% by weight of chromium oxide and have a ratio of calcium oxide to silicon dioxide content in the range of 0.1 and 2.

Description

The invention also relates to the lining of the hearth furnace transitions, in particular the tilting tandem furnace, and seeks to ensure the operational safety and reliability of these transitions during the operation of the furnace.

The transitions of tandem furnaces are part of the refractory lining of the furnace, which forms the transition of the vault to the side walls of the furnace. Due to their geometric arrangement and orientation to the furnace nozzles, the most exposed and stressed places are refractory linings, so their durability determines the length of the campaign and thus the work cycle of individual tandem furnaces. The transitions are still made, for example, of chemically bonded magnesium chromium. Its disadvantage is that it is relatively less resistant to erosion. The transitions are also made of fired and fused magnesite. Their disadvantage is that they are relatively less resistant to temperature changes. Transitions from sta-. viv based on alumina or silica are not coexisting with the slag order of the tandem process, and transitions from carbon-containing structures burn in the kiln atmosphere. The transitions are also made of conventional fired magnesitchrome, which is, however, unsatisfactory due to its low durability. Operational reliability of transitions during operation can be ensured by making them from sophisticated refractory stones made on the basis of fused magnesium oxide with the addition of chromium ore. However, their disadvantage is the high energy intensity and the relatively high price. Also, too dense or, on the contrary, too porous basic transitions ee did not prove successful. The first for low resistance to temperature changes, the second for low corrosion resistance.

According to the invention, the above-mentioned disadvantages are eliminated by the lining of hearth furnace transitions made of fired magnesitchrome stones, characterized in that the magnesitchrome stones have a different porous structure, so that part of the magnesitchrome stones (1) has a porosity of 11 to 16 vol. 2 / has a porosity of 16 to 2Í 4 · vol., Where the proportion of stones / 1 / in the lining is 1/3 to 4/5 and the proportion of stones / 2 / in the lining is 1/5 to 2/3. It is a further object of the invention that the calcined magnesitchrome stones (1), (2) contain from 8.0 to 20.5% by weight of chromium oxide and the ratio of calcium oxide content to silica content is 0.1 to 2.0.

The advantage of the lining of the hearth furnace transitions according to the invention is that the lining of the transitions as a whole has balanced properties mainly in terms of porosity, which determines its wear not only in terms of corrosion but also in terms of resistance of the lining against temperature changes. Thus, by superposition of fired magnesitchrome stones (1), (2) in the lining of the transitions, a substantial increase in the durability and reliability of the transitions of the tandem furnaces is achieved, as can be seen from the following comparison (Table 1). The advantage is also the relatively low price of the lining.

Table I

Comparison of operational reliability of transitions of tandem furnaces made of different types of constructions

TYPE CONSTRUCTION RELIABILITY chemically bonded magnesitchrome 0 ea internal reinforced magnesitchrome 0 EI commonly fired magnesitchrome 41.5 Ei magnesitchrome according to the invention 95 to 100 4

As an exemplary embodiment of the lining of the transitions according to the invention, there are mentioned transitions which have been produced in the following way:

1. 80 4 · fired magnesitchrome stones with a porosity of 13 to 16 vol. Both groups of stones had a calcium to silica ratio of 1.08 and a chromium oxide content of 12.6% by weight. With the transition made in this way, 100% reliability was achieved during the operation of the tandem furnace campaign, so that this node did not have to be repaired at all during operation.

-2CS 268 296 Bl

2. In the lining of the tandem kiln transitions le, 50 .s. Stones with a mastery of 11 to 15.9 vol. 20.3% by weight and a ratio of calcium oxide content to silica content in the range of 1.1 to 1.6. The transitions walled in this way showed 98% reliability in the operation of tandem furnaces, i.e. out of 100 bricked-out crossings, only two crossings had to be repaired during hot repairs in the difficult working conditions to which the white masonry crew is exposed.

Claims (2)

OBJECT OF THE INVENTION 1. A lining of a hearth furnace transitions formed of fired magnesitchrome stones, characterized in that the magnesitchrome stones have a different porous structure, so that a part of the magnesitchrome stones (1) has a porosity of 11 to 16% by volume. / has a porosity of 16 to 21% by volume, the proportion of magnesitchrom stones / 1 / in the lining being 1/3 to 4/5 and the proportion of magnesitchrom stones / 2 / in the lining being 1/5 to 2/3, 2. The lining of the hearth furnace transitions according to item 1, characterized in that the magnesium chromium stones (1), (2) contain from 8 to 20.5 [mu] l by weight of chromium oxide and have a ratio of calcium oxide content to silica content of 0.1 to 2 , 0.