SU1525213A1 - Slag-forming mixture for processing cast iron of working layer of double-pour rolls - Google Patents

Abstract

The invention relates to metallurgy, in particular to slag-forming mixtures, and is intended for the treatment of cast iron of a working layer of bilayer rolls produced in an open-hearth or flame furnace. The aim of the invention is to reduce the duration of smelting and increase the bleachability of cast iron with increasing yield and reducing the cost of cast iron. Slag-forming mixture for the treatment of cast iron of the working layer of two-layer rolling rolls contains, in wt%: slag production of silico-manganese 10-25

coking 25-40, sludge abrasive processing mill rolls the rest. The use of the mixture allows to reduce the duration of melting by 10.2%, to increase the bleachability of cast iron by 39.8% with an increase in yield of 6% and decrease in the cost of cast iron by 6.22%. 1 tab.

Description

one

(21) 4429634 / 31-02

(22) 05.23.88

(46) 11/30/89. Bul No. 44

(71) Dnipropetrovsk Metallurgical Institute

(72) N.A. Budag nts, V.A. P mov,

O.V. Bubbles-Uvarov, A.V. Vikhrov, V.N. Komlkov, A.A. Orphan, V.P. Saushin, R.Kh. Gimaletdinov, S.P. Pavlov and V.Ya. Gapotchenko

(53) 669.15-198 (088.8)

(56) USSR inventor's certificate K 1089137, cl. From 21 to 1/00, 1984.

Author's certificate of the USSR 1447863, cl. From 21 to 1/00, 1986.

(54) SLAG MIXTURE FOR PROCESSING THE IRON OF THE WORKING LAYER OF DOUBLE-WALL ROLLING ROLLS

(57) The invention relates to metallurgy, in particular to packaged mixtures, and is intended to process cast iron of a working layer of double-layer rolls produced in an open-hearth or flame furnace. The purpose of the invention is to reduce the duration of smelting and the bleaching of pig iron while increasing the yield and reducing the cost of pig iron. Slag-forming mixture. For treating cast iron of working layer, bilayer mill rolls contains, in wt%: spackle made from silicomanganese 10-25; coking 25-40, sludge abrasive processing mill rolls the rest. The use of the mixture makes it possible to reduce the duration of smelting by 10.2%, increase the bleaching capacity of cast iron by 39.8% with an increase in yield of 6% and a decrease in the cost of cast iron by 6.22%. 1 tab.

i

(L

The invention relates to metal. Lurgia, in particular to ishakoobrazuyuschih mixtures, and is intended for the treatment of cast iron working layer of two-layer rolling rolls produced in an open-hearth or flame furnace.

The aim of the invention is to reduce the duration of smelting and improve the iron bleachability while increasing the yield and reducing the cost of iron.

Spack forming mixture for working cast iron of working layer of double-layer, mill rolls contains pshak of silicomarg production, coking and cutting abrasives of mill rolls

10-25 25-40

with the following ratio to onentoB, May. %:

Slag of production of silicomanganese Koksik Slime of abrasive processing of rolling

rolls Else Due to their very high hardness, the surface treatment of the barrels of double-layer rolled rollers is not done with a blade tool, but with abrasive electro-corundum wheels (24A-PP-99.5% Alg.0z). In this region

 l

:with

A large amount of sludge containing 10-15% of particles and 85-90% of iron particles of the following chemical composition, May, is produced. %: C 2.65-2.95; Si 0.42-0.55; Mp Q, 45-0.60; Cg 0.55-0.80; Ni 2.70-3.95; Mo 0.05-0.5. This psham was previously disposed of and dumped. The high content in the waste sludge of all the alloying elements included in the cast iron of the working layer of double-layer rolls predetermines the high technical and economic feasibility of its use in the smelting of alloyed iron as a substitute for the corresponding expensive ferroalloys.

The main quality characteristic of liquid iron for rolling rolls is its high bleachability, i.e. the ability to harden with the formation in the casting of a large-size macrostructural zone of pure chill (with the structure of cementite + perlite) with a short transitional macrostructural zone (with the structure of cementite + perlite + graphite). In valtseleyteynom production it is evaluated by the criterion of quality.

 X + Z

where X is the value of hona pure chill, mm; Z - the size of the transition zone, mm.

High bleaching smudge of liquid iron for rolls is provided only at low concentrations of ferrous oxide in the furnace putty, and therefore the proposed mixture, in addition to alloying the iron, should also ensure that the process of reducing iron oxide in the furnace slag is effective.

The quality of double-layer rolls is greatly influenced by the duration of melting, with an increase in which non-metallic inclusions with a size of 8–10 µm appear in the non-graphite white working layer, which leads to a 30–40% decrease in the durability of the rolls, and therefore the proposed mixture should also reduce duration of melting.

When optimizing the proposed composition of the alloying-reduction mixture for the treatment of cast iron of the working layer of double-layer rolls, experimental melting was carried out in a 30-ton open-hearth furnace with an acid lining. The yield of the metal is determined by the material balance of the results of the bottoms:

(um

dm

About ml

100%

- five

0

five

0

five

0

five

where Q, is the amount of liquid metal in the ladle, kg;

mz the amount of metal introduced into the furnace with metal-roll, kg.

In this case, metal loss in the form of crowns with a putty was determined by magnetization of the calculated weights of the ground final slag. The chemical composition of the slag was determined by a known method. The whiteness of roll melts was assessed by the criterion of the quality of ac according to the ratio of macrostructural zones in the roll-up technological sample.

The results of the analysis of comparative heats are given in the table.

The absence in the composition of the mixture of a component that functions as a reducing agent for ferrous oxide of shpak leads to a lengthening of the smelting process and an increase in the carbon loss of the metal. Therefore, in the proposed composition, iron oxide in the putty was used as an effective deoxidizing agent by direct contact with it, the necessary amount of which was determined according to the results of the experimental strips (see table). When the content of coke in the mixture is less than 25%, the metal waste increases, the yield decreases, cast iron bleachability deteriorates (smelting 2 and 7), and an increase in its content of more than 40% is accompanied by the formation of heterogeneous viscous putters, which reduces the efficiency of its use (smelting 10) or leads to an increase in cost, as it reduces the proportion of the alloying component in the mixture (smelting 6).

The use of the proposed shaker mixture produced by silicomanganese is justified by the high concentration of manganese oxide in it (18.6-23.8%), which liquefies acidic slags well, reducing their viscosity, which improves the kinetics of the reduction processes in shpak. Ensuring that the concentration of manganese oxide in the smelting slag increases, the slag of silicomanganese also contributes to the reduction of manganese intoxication.

51

A decrease in the amount of the silicone manganese donkey in the mixture of less than 10% (smelting 11) due to an increase in the amount of abrasive sludge leads to an increase in the oxidation of the metal, as a result of which the yield and whitening decrease. Reducing the amount of silicon man's pork due to an increase in the amount of coke (smelting 10) leads to an increase in the viscosity of the smelting pelt, a deterioration in its assimilating ability over nonmetallic inclusions, which leads to a decrease in bleaching, as well as to a decrease in yield due to increased metal losses wrenches with putty. An increase in the amount of silicomanganese spat in a mixture of more than 25% (melting 7 and 14) is accompanied by both a decrease in the viscosity effect of the slag on the rate and completeness of the reduction of ferrous oxide, and an increase in the corrosive effect of slag on the hearth and on the acid lining slopes of the open-hearth furnace. Since this reduces the amount of coke or abrasive sludge, the yield is reduced due to increased metal loss (smelting 7) or the cost increases due to a decrease in the proportion of metal alloyed fraction in the mixture (smelting 14)

When the amount of abrasive slag decreases below 35% (smelting 15), the amount of slag in the furnace increases, which leads to an increase in the duration of smelting, as well as the cost, as the amount of alloying elements introduced by metal decreases. part of the mixture. With an increase in the amount of abrasive sludge above 65% (smelting 16), the oxidation of metal and slag increases, which leads to a deterioration in the whiteness of cast iron.

The use in the proposed sludge mixture of abrasive treatment of the rolls in the established limits leads to an increase in the iron content of nickel, the transition from the metal part of the sludge, which leads to an increase in the strength and hardness of the cast iron rolls. Therefore, when using charge materials commonly used for smelting iron of the working layer of rolls of the best LPHNd - 62, it is possible to obtain

52

Q 5 0 5 o

.Q

P

five

five

five

136

To cast castings, according to the mechanical conforma tions, the corresponding LPHN rolls are 70 and LPHIMd- 72, with lower alloying costs. Since the metal part of the sludge is 85-90%, the introduction of a mixture with sludge, which is an unutilized production waste, also provides an increase in the volume of metal produced, which is equivalent to a decrease in the unit cost of production (1 ton cast).

Amphoteric window opener in the slurry contributes to reducing the viscosity of acidic slags.

Entering a coke-type reducing agent into the composition allows to increase the speed and completeness of slag deacidification, and using abrasive processing of rollers as an alloying component of the sludge mixture provides a more complete and faster transition of alloying elements from the mixture into liquid iron. pig iron sludge, rather than by reducing the furnace slag oxides). The lower content in the proposed mixture of ballast oxides, which increase the amount of furnace slag, which isolates the metal bath from the torch and makes it difficult to transfer heat to it, reduces the duration of smelting and fuel consumption. Alumina, which is part of the slurry, reduces the viscosity of the furnace slag together with the silicomanganese slag, improves the kinetic conditions of its deoxidation and improves the whiteness of the iron. The low cost of the new component of the mixture - abrasive sludge, which makes expensive alloying elements in the cast iron, ensures high technical and economic feasibility of using the mixture to increase the yield of usable metal in open-hearth smelting due to reduction of its carbon loss and losses with slag in the form of korolkov.

Example. In a 30-ton open-hearth furnace with an acidic lining, cast iron is melted for the working layer of double-layer rolls of the LPHNMd-72 version of the following chemical composition, May. %: C 2.95; Si 0.48; Mp 0.55; Cr 0.65; Ni 3.65; Mo 0.35. The bale rolls and the roll blast furnace cast iron CV-1 used as the charge.

A mixture of slag from the production of silico-manganese (17.5%), coke (32.5%) and cutting mill abrasive cutting (50.0%) in an amount of 12.0% by weight of metal-rolls is loaded into the furnace, the iron is heated to 1470 ± 5 ° and release into the bucket.

When smelting is carried out, the bleaching ability of cast iron is evaluated by the value of criterion A | according to the ratio of the values of the macrostructural zones in the fracture of the vallee technological test.

The yield of metal is evaluated by the material balance of the melt by the difference in the amount of metal loaded into the furnace and obtained from the furnace.

The loss of metal in the form of crusts with slag is estimated by the amount of magnetized metal in the calculated weights of the crushed slag.

Thus, the application of the proposed mixture for the treatment of cast iron of the working layer of double-layer rolling rolls reduces the duration of smelting by 10.2% and increases the bleachability of cast iron by 39.8% while increasing the yield of the metal by 6% and reducing the cost of casting.

In addition, the application of the proposed mixture reduces the consumption of gray iron for the operation of washing the casting molds of the two-layer rolls, and also significantly reduces the scrap cast on the gas shells in the working layer of rolls, provides not only a significant effect in the production of mill rolls due to improving smelting performance, eco-homiih charge materials and ferroalloys, reducing the cost of casting

but also in the area of their consumption at metallurgical plants by increasing the operational durability of the rolls, increasing the productivity of rolling mills by reducing their unscheduled stops for the handling of rolls.

An additional effect is provided due to the involvement in the production of a new product, which is currently not utilized waste of valtseitny production, which will allow not only expanding the raw material base for expensive alloying elements, but also solving the environmental plan - eliminating dumps of valtiteyny production, freeing land from them.

Claims (1)

Invention Formula Slag-forming mixture for the treatment of cast iron of the working layer of two-layer rolling rolls, containing slag from the production of silico-manganese, characterized in that, in order to reduce the duration of smelting and increase the bleachability of the pig iron with increasing yield and reducing the cost of pig iron, it additionally contains coking and abrasive machining slurry in the following ratio, wt.%: 0 Elak production of silicomanganese Koksik Slurry abrasive treatment of mill rolls 10-25 25-40 Rest . Preparation of cast iron using a mixture of the prototype. Preparation of cast iron using the proposed mixture, 1525213 ten Table continuation