SU1013095A1 - Flux for continuous casting of cadmium bronze - Google Patents

Abstract

1. FLUSH FOR CONTINUOUS CASTING OF CADMIUM BRONZE Including sodium oxide, silica and brr oxide, characterized in that in order to improve the surface quality of the ingots, reduce irrecoverable metal losses and toxic precipitates of cadmium oxide, the flux additionally contains cryolite and carbon-containing material in the following relation, as follows, the following correlation of cryolite and carbonaceous material in the following correlation of the relevant ratio of the following correlation of the corresponding ratio of the corresponding information of the corresponding ratio of the corresponding ratio of cryolite and carbon-containing materials, the flux of bluing material; , wt.%: Sodium oxide 30-35 Silica 10-15 Cryolite 10-20 Carbonaceous. Material1-5 Boron oxide Remaining 2. Flux according to claim 1, characterized in that it contains as carbonaceous material containing charcoal, 3. Flux according to claim 1, characterized by the fact that it contains calcined charcoal powder as a carbon-containing material.

Description

The invention relates to metal, in particular, to the development of coating flux for continuous casting and melting of copper and its alloys, for example cadmium bronze. Known coating for continuous casting of copper alloys to melt dehydrated borax 1. The use of dehydrated borax cannot be recommended when smelting and casting copper and copper low-alloyed alloys, as the film of dehydrated borax does not hold on the meniscus surface of the metal of the crystallizer in connection with a significantly different character solidification of these alloys in comparison with highly 1-HINK brass. Known flux for continuous casting of steel, including cryolite, crust, boron oxide, cement, coal type 2. However, this flux is unfit for continuous casting of copper alloys due to possible saturation of the melt with sulfur, moreover, it does not provide satisfactory of ingot surface quality. A series of flux coatings is also known, containing borax, cryolite, sodium silicate 3, soda, cryolite, sodium chloride 4, intended for smelting copper alloys. However, these coatings do not meet the requirements of fluxes, because poor coating ability of these compositions of low-alloyed copper alloys. The closest to the invention to the technical essence and the achieved result is a flux for casting copper-based alloys, including sodium oxide, silica and boric anhydride 15. However, using the known method for continuous casting of nadium bronze does not provide quality surface ingots., Because no lubrication of the surfaces of the hardened ingot and the mold in the zone of the solid crust formed, as well as rupture of the flux cover on the meniscus surface Ferrous materials. This leads to an increase in toxic cadash oxide deposits and to an increase in irretrievable metal losses. The aim of the invention is to improve the surface quality of the ingots, reduce the irretrievable metal losses and toxic emissions of cadmium. The goal is achieved by the flux for continuous casting of cadmium bronze, including sodium oxide. , silica and boron oxide, additionally contains cryo .-. lit. and carbon-containing material with the following content of ingredients, weight,%; Sodium oxide 30-35 Silica 10-15 Cryolite 10-20 Carbonaceous material 1-5 Boron oxideOther The flux may contain charcoal or calcined charcoal powder as a carbon-containing material. The proposed flux provides good wetting between carbon and the melt of the other components in the temperature range of the coating (. Due to this coating property, carbon easily penetrates into the zone of the ingot surface forming through the liquid contact zone of the molten metal with the crystallizer wall, and reducing the coefficient -. rubbing surfaces, provides a high-quality surface of ingots (without cracks and tears). The presence of carbon in the flux (wetted base) makes the flux two-phase, which determines the satisfactory covering ability of the flux, the exothermic nature of the interaction of the carbon flux with the oxygen of the air leads to the heating of the flux cover from above, while the specific flux consumption (kg / cm) increases without loss of processability. This also leads to an improvement in the covering power of the flux and reducing the amount of cadmium oxide emissions. Sodium oxide present in the composition of the flux at the melting and casting temperatures of the alloy, entering into an exchange reaction with the carbon of the flux, decomposes to pure sodium . Plastic sodium, which has a high thermal conductivity, deposited on the walls of the mold, serves as an additional lubricant to carbon for carbon. during the casting of surfaces, which, without deteriorating the process of heat transfer from the ingot to the walls of the mold, also improves the state of the ingot surface. The simultaneous presence of an unstable complex compound, cryolite and sodium oxide, in the flux at temperatures allows them to react with each other to form solid-phase products alumina oxide type reactions. This also leads to an improvement in the covering power of the flux, since it forms a two-phase mixture, where the liquid component is cemented by a wettable

solid base, well kept on the surface of the intensively stirred metal in the mold cavity. .

The introduction of cryolite to the flux composition makes this compound universal, since the cryolite inertness to the chamotte lining of the furnace shaft prevents the lining silica from dissolving in the sodium oxide – boron oxide melt, and this composition can be used as a coating flux in the furnace and pouring box when melting cadmium bronze. The presence of carbon improves the coating capacity of the flux, when melting the alloy in induction channel furnaces, leads to an increase in the viscosity of the composition and the durability of the chamotte lining, the exothermic nature of the interaction of the carbon of the flux with the oxygen of the air also appears. All this also leads to a decrease in the amount of cadmium oxide emitted, a reduction in irrecoverable metal losses for waste and slag, and an improvement in the sanitary and hygienic working conditions of the plant. Flux is prepared as follows.

Boric anhydride (B jJrOC T 1006875 is mixed in a certain proportion with sodium oxide (obtained by high-temperature decomposition of caustic soda MAON GOST 4328-77 oxide

0 - silicon (SiOi) rOCT 9428-73 Sprayed quartz) and remelted and crushed technical cryolite GOST 10561-73 in ball melt for 0.5 h to obtain a homogeneous composition, Carbonaceous additive in the form of GOST charcoal 7657-74 or calcined charcoal charcoal powder, GOST 7657-74 is added to the mixture immediately, immediately before feeding the flux

0 melt meniscus,.

Tables 1-3 show the technological and physicomechanical characteristics of the proposed flux,

Table

Silica

Sodium oxide cryolite

coals

100

The ratio of the initial and final concentration is 1.05 1.05 1.60 С Cp / C, weight, 0.65 0.55 1.40

ten

50

15

13

thirty

32

ten

15

1 49

25

35

37

6

Table 2

1.20

1.60 1.50 1.10 Constant mass1, 9.10-3.3-10-4 transfer about, cm / s

The amount of cadmium oxide released into the atmosphere of the workshop from the metal surface per unit of time, g / s

The total length of defects, per unit of ingot surface, vsM mm

The average depth of surface defects, determined with a needle probe, mm

To search for the optimal composition of the flux, comparative studies of cadmium carbon from melts under various covers were carried out by changing the concentration of cadmium in samples taken from the melt before and after an hour exposure in an alundum crucible (L Co / s).

 The intensity of the burn was characterized by mass transfer constant 6 (cm / s

The weight of the sample is 220 g, the surface of the metal meniscus is 13.8 cm in the crucible, the exposure time is 1 hour, the thickness of the coal cover is 3 cm, the thickness of the flux cover and the cover of soot is 0.5 cm, The values of Co / s given are averaged over a series of experiments.

On the basis of the data obtained, the intensity of cadmium deposits from the metal surface was calculated. The calculations took into account the total surface of 5p 0.95 precipitates of the crystallizer 0 200 mm and the furnace with a casting box), as well as the fact that 1./5 of the total flow of Ksmmi oxide in the atmosphere 2

0,0670,0330,0330,033

Table 3

0,250

0.0530.090

0.069

1.50

1.50 2.00

4.00

ru. shop. The cadmium oxide emissions were in the corresponding molar fractions by the reaction of 2 Cd f 02. 2CdO,

The wettability of the graphite lining with the flux melt was carried out by visual determination of wetting angles. As a result of research, it was found that the wettability of graphite with fluxes of compositions 4-6 is much higher than the similar parameter for the flux of composition 3. The wetting angle is increased by about 4 times.

Thus, as follows from the table, 2 and 3, the flux of composition 5 has the best technological properties in continuous casting of cadmium bronze,

The introduction of flux components below the lower limits increases the evaporation of cadmium, and above the upper limits degrades the quality of the surface of the ingot

The use of the invention allows to obtain ingots of cadmium bronze without internal defects with a crushed macrostructure and high-quality 0.71LO 0.35., 35-, 35-th state of the surface, to ensure the safe operation of the staff at the plant during smelting and LKT. Thie of the designated alloy, as well as reduce the irretrievable loss of metal on. waste, and slag 1.5–2 times with simultaneous use of flux as a covering of the mechsl in the mold, furnace and in the bottling box. The technical and economic effect of the introduction of flux consists of reducing the irretrievable metal losses in waste and slag and saving on the construction of special air-cleaning facilities. The expected economic effect from the introduction of this invention will be 11 rubles. per ton of suitable products

Claims (3)

1. FLUX FOR CONTINUOUS CASTING OF CADMIUM BRONZE, including sodium oxide, silica and boron oxide, characterized in that in order to improve the surface quality of the ingots, reduce the irreversible loss of metal and toxic emissions of cadmium oxide, the flux additionally contains cryolite and carbon containing material in the following ratio ingredients, wt.%: Sodium oxide Silica Cryolite Carbon-containing material Boron oxide 30-35 10-15 10-20 1-5 Else 2, Flux pop. 1, characterized by the fact that it contains charcoal as a carbon-containing material. 3. Flux according to π. 1, the fact that, as a carbon-containing material, it contains calcined charcoal powder. SU „„ 1013095>