SU1244189A1 - Mixture for treating cast iron melt - Google Patents

Description

 I

The invention relates to metallurgy and can be used in the foundry industry for desulphurization and modification of molten iron in the manufacture of castings for various purposes and nomenclature.

The aim of the invention is to increase the degree of desulfurization and modification of cast iron.

The proposed mixture for the treatment of molten iron contains coke shale ash and calcium carbide in the following ratio, wt.%; calcium carbide 75-90; ash coke shale 10-25.

Shale ash coke (KSZ) is a utilized waste product from the processing of combustible shale from the Baltic deposit in chambers. The chemical composition of the COP is regulated by TU 38.10936-81., Wt.%:

Massowa Dol

carbon C 16-18 Mass fraction of volatile V 18-20 mass fraction of total moisture W 1 3-35 mass fraction of ash A68-74

The chemical composition of the mineral tea KSZ5 wt.%:

CaO29.57,

SiOj15.67

MgO3.48

, 62,

Reg. About ,,. 3.10 K OIs9

soa4.8

ppp36, 89

Mineralogical composition KSZ, masD;

Massowa Dol

carbon With 16jo-l8, p

Massow da CaCO

Mag.sov dol clay substances

1244189

Studies on thermal and electrothermal treatment of CSR showed that the melting point of the CSR is about and the reaction between calcium and carbon entering the PSK into the CSR is more easy, because the reaction starts and passes when the starting materials contact at the molecular level, which predetermines a significant increase in the activity of the carbon introduced into the melt.

Calcium carbide (GOST 1460-81) of the following composition was used for preparation of the pre-mixed mixture, wt%:

CaC5

Sic

Cao

Sio

,

MnO MgO C

67.5-73.5

0.43-5.08

8.0-20.2

0.42-7.85

1.74-3.58

0.17-0.52

0.1-0.63

Oh. 10-0.48

1.57-3.3

0.02-0.06

0

five

P0.04-0.015

The mass ratio of calcium carbide and coke shale ash (75: 25-90G10) was determined experimentally, and: the depletion of the conditions for the most Effective desulfurization and modification of the cupola cast iron.

With a smaller mass ratio of calcium carbide to KSZ in the mixture, i.e. € 74g25e, a large amount of gases is released during decomposition of the CSR, which leads to a strong bubbling of the molten iron and possible metal release from the ladle, while the effectiveness of desulfurum gas is practically not increased. An increase in the content of carbon introduced together with the CZS ,, does not lead to an increase) of the modifying effect 5

With a higher mass ratio of calcium carbide and KSZ, i.e. 90:10 ;, the degree of desulfurization and

the modification of cast iron is reduced due to the insufficient introduction of carbon and the gas-forming component. PRI im p The iron was smelted in an induction furnace, and cast iron billets were used as a charge, the chemical composition of which after melting is as follows, in May.%:

C3.0-3.2

Si2.0-2.2

MP 0.5-0.8.

S0.08-0.1

Р0,08-0,1,

The molten iron was overheated in an induction furnace up to 1380 ° C. The cast iron was desulfurized in a 50 kg bucket with a capacity of 700-800 ° C.

The cast iron was desulfurized in the following manner.

At the bottom of the pouring ladle, a mixture was introduced from the measuring container to the & all for cast iron

2441894

cast iron From the induction furnace, molten iron was poured into the casting ladle, which contained the mixture to process the iron. Melt the iron - on top in a ladle 120-300 s (2-5 min.). Slag was scraped from the surface of the metal and poured on the chill to determine the chemical composition of the pig iron.

JQ Cooking Ingredients

The proposed mixture was crushed to fractions of 0.5-1 mm and mixed without pre-drying before they were introduced into the molten iron.

 A known desulfator was prepared, observing the known ratios of its components.

The treatment efficiency of the molten iron by the known and proposed mixtures was evaluated by the degree of desulphurization of the iron and the tendency of the iron to chill at an equal consumption of mixtures in the amount of 1.5% of the mass of the molten iron melted.

The results of the comparative tests are shown in the table.

The proposed mixture for the treatment of molten iron has advantages over the known mixture. The degree of desulfurization was 15.8-22.0%, and the efficiency of modification was 33.37% (6.7 variant) compared to the known mixture.

The use of the proposed mixture with a ratio of components above or below the specified limits is impractical because the efficiency of desulfurization and modification is worsened.

The effectiveness of the proposed mixture is associated with a special state of carbon, which is in the CSR not as a mechanical mixture with calcium carbonate, but as a chemical compound that is formed when treating combustible shale in chamber furnaces at a temperature of 420-430 C, which is significantly lower. The temperature of liquid iron, in addition, carbon in the CSA is also present as high molecular weight compounds, which decompose when introduced into: molten iron with release of highly active

Editor N.Gorvat Order 3775/28

Compiled by Sorokin Tehred. V. Kadar

Corrector

Circulation 552 Subscription BNIIPI of the State of the USSR Stet

for inventions and discoveries 113035, Moscow, Zh-35 Raushsk, emb. 4/5

. Production and printing company, Uzhgorod, Projecto st., 4

441894

atomic carbon. The gaseous phase, which is formed during the decomposition of coke shale ash, consists of carbon dioxide and volatile substances and contributes not only to additional mixing of the molten iron with the components of the mixture, but also creates a protective atmosphere above the melt mirror, which preserves calcium carbide and the surface is blast, iron from oxidation.

Using the proposed mixture allows an increase in desulfurization efficiency by an average of 20% and modification by an average of 30%. The economic effect of using the invention can be obtained in foundries of engineering plants and in specialized foundries in the production of nodular cast iron by reducing the cost of the components of the mixture, the consumption of spheroidizing codifiers, and the cost per liter of quarts, bleaching of castings for chill.

15

20

25

Proofreader M. Demchik

Claims (1)

MIXTURE FOR CAST IRON MELT PROCESSING, containing calcium carbide, characterized in that, in order to increase the degree of desulfurization and modification of cast iron ’, it additionally contains shale ash coke in the following ratio, wt.%: Calcium Carbide 75-90 Coke shale ash 10-25 Q0 ζ ©