SU1560570A1 - Method of refining ferrosicilium from aluminium - Google Patents

Abstract

The invention relates to ferrous metallurgy, specifically to the production of ferrosilicon used for the manufacture of iron casting modifiers characterized by a reduced content of aluminum, calcium. The purpose of the invention is to reduce the loss of the alloy. It is proposed to granulate ferrosilicon in an oxidizing atmosphere, and when the melt is heated to a temperature of 50-150 ° C above the liquidus temperature, slag is removed. Compared with the known method, the proposed method allows reducing the loss of the alloy by 3-4 times while obtaining the residual aluminum content not exceeding 0.45% and calcium to traces. 1 tab.

Description

The invention relates to ferrous metallurgy, specifically to the production of ferrosilicon used to manufacture cast iron modifiers characterized by a reduced content of aluminum and calcium.

The aim of the invention is to reduce the loss of the alloy.

The method consists in the fact that the granulation of ferrosilicon is carried out in an oxidizing atmosphere, then melted and after heating the melt at 50-150 ° C above the liquidus temperature, slag is charged, after which the heating is continued.

When granulating ferrosilicon in an oxidizing atmosphere, for example, in air, impurities Al, Ca, Ba, Mg, which are in the melt, are actively oxidized by atmospheric oxygen, forming a film on the surface of the granules containing oxides A1A03, CaO, BaO, MgO. The minimum amount of impurities remains inside the granule. Oxidation is promoted by the diffusion of impurity atoms onto the surface of the granule with a sharp decrease in the temperature of the metal during granulation. When the melt is heated to a temperature higher than the liquidus temperature by less than 50 ° C, the metal and slag are not completely separated, which increases the metal loss during slag removal and contaminates the melt with impurities recovered from the slag during subsequent heating. Three heated to a temperature exceeding the liquidus temperature by more than J50 ° C, the alloy is contaminated with impurities that pass from the slag.

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After the slag layer has been formed, it is removed by known methods, for example scrapers. The amount of slag is small and amounts to only 0.5-1.5% of the mass of the melt, i.e. 10-20 times less than in a known way, which reduces the loss of metal from the slag. In addition, there is no need to melt and heat a large amount of slag, for the preparation of which additional special materials with a low content of alumina are necessary.

Example. The melt of the 65% ferrosilicon composition, wt.%: Si 66.3, A1 1.9, Ca 0.6 - was released from the ore-thermal furnace into a ladle mounted on a granulation unit.

The melt through the hopper and the chute was directed to the water nozzles, where it broke up in an atmosphere of air into pellets that fell into the tank with running water. From the tank, the tray ferrous pellets were loaded into jars with gaps in the bottom for draining water and drying.

The chemical composition of the obtained granules, wt.%: Si 65.9, A1 1.3, Ca 0.3.

The obtained granules in the amount of 1.5 tons were loaded into a bath of an electric furnace with a capacity of 3200 kW, the furnace was turned on and the electrodes were lowered before the arc was ignited. As the wells were melted, the granules were scooped up to the electrodes, not allowing the melt to overheat. The melt temperature was measured with an immersion thermocouple.

The liquidus temperature of 65% ferrosilicon is 1250 ° C, therefore, at a melt temperature of 1300-1400 ° C, which is 50-150 ° C higher, the furnace was turned off and the resulting viscous slag was scraped off and removed from the furnace. , the melt overheated to a temperature of 1420-J500 ° C, which provided the conditions for metal casting, and released the melt through the furnace log into the cast-iron mold.

When refining by a known method, 0.2 tons of silicate slag (50% SiO, 34% CaO, 13% MgO) were pre-melted in the furnace bath, after which 65% ferrosilicon granules obtained in the atmosphere nitrogen to the experimental granulation

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Noah installation. Simultaneously, silicon carbide was introduced into the slag in the range of 1-10% (25 kg, i.e. 5% silicon carbide) were introduced per 500 kg of granules. The metal melt was released through a tap hole with a slag cut-off.

The results of the experimental heats are shown in the table.

As can be seen from the data in the table, a reduction in alloy loss compared with the prototype method is achieved with the recommended parameters. In addition, when the melt is subsequently heated (after slag removal) to a temperature of less than 170 ° C above the liquidus temperature, metal losses in the form of buildup on the furnace walls sharply increase, and heating to a temperature exceeding more than 250 ° C, the liquidus temperature is impractical as the specific energy consumption increases, and the metal loss does not decrease. When smelting without removing schlack (test 12), even at the recommended temperature conditions, 1 impurity content in the alloy increases.

The use of the proposed method allows to reduce the cost of producing refined metapp {increase the yield, simplify the process, eliminate granulation in a nitrogen atmosphere, and slag processing.

In addition, the resulting metal is characterized by a reduced (to trace) content of calcium, barium, magnesium.

Claims (1)

Invention Formula The method of refining Ferrosilicon from aluminum, including granulation of a liquid alloy, subsequent melting of the obtained granules, overheating the Raishava to a temperature of 170-250 ° C above the liquidus temperature, characterized in that, in order to reduce the loss of the alloy, granulation of the liquid alloy is conducted in an oxidizing atmosphere, when the granules melt, the metal is heated to a temperature of 50-150 ° C above the liquidus temperature, slag is removed at this temperature, after which heating is continued.