RU2468109C2 - Method for aluminothermal production of ferromolybdenum - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method includes the following: staged loading and fusion penetration of a charge, containing a molybdenum concentrate, ferrous scale, ferrous punching, lime, ferromolybdenum slag, aluminium and separation of metal and slag. At the first stage the charge is loaded with the speed of 680-850 kg/m²·min., containing the molybdenum concentrate, ferromolybdenum slag, ferrous punching, 90-95% of lime from its mass for melting, 65-75% of ferrous scale from its weight for melting and aluminium in the amount of 0.98-1.0 of ferromolybdenum stoichiometrically required for recovery of alloy elements. At the second stage the charge is loaded with the speed of 105-125 kg/m²·min., containing 25-35% of ferrous scale from its weight for melting, 5-10% of lime from its weight for melting and aluminium in the amount of 2.6-3.0 of ferromolybdenum stoichiometrically required for recovery of alloy elements, and the melt is heated under arcs of an electric furnace of 3-5 times of charge melting.

EFFECT: invention makes it possible to increase extraction of molybdenum in an alloy and alloy quality.

6 ex, 1 tbl

Description

The invention relates to the field of metallurgy, and in particular to a method for aluminothermic production of ferromolybdenum, which includes the stepwise loading and melting of a mixture containing molybdenum concentrate, iron oxide, iron sheathing, lime, ferromolybdenum slag, aluminum and separation of metal and slag.

The technical result of the invention is to increase the extraction of molybdenum into metal and improve the quality of the alloy.

SUMMARY OF THE INVENTION

In the first stage

Download and melt the mixture at a speed of 680-850 kg / m ² · min, containing molybdenum concentrate, iron sheathing, ferromolybdenum slag, 65-75% of iron oxide from its mass for smelting, 90-95% of lime from its mass for smelting and aluminum in the amount of 0.98-1.0 of the stoichiometrically necessary for the restoration of ferromolybdenum alloy elements.

In the second stage

Download and melt the mixture at a speed of 105-125 kg / m ² · min, containing 25-35% of iron scale from its mass for smelting, 5-10% of lime from its mass for smelting and aluminum in an amount of 2.6-3.0 % of stoichiometrically necessary for the restoration of ferromolybdenum alloy elements and melt is heated in an electric furnace 3-5 times of charge melting.

Known carbon reduction process of smelting ferromolybdenum per block. Briquettes of molybdenum concentrate, coal powder, lime and iron chips are melted in electric furnaces. The process is characterized by high energy consumption, increased losses of molybdenum and a high carbon content in the alloy.

The closest technical solution to the invention is a silicoaluminothermic method for producing ferromolybdenum (prototype), including preparation, melting of the charge, separation of metal and slag containing 4200 kg of molybdenum concentrate, 756 kg of iron ore, 966 kg of iron sheathing, 1260 kg of 75% ferrosilicon, 294 kg secondary aluminum, 126 kg of lime and 126 kg of fluorspar. The mixture is loaded into a crucible lined with fireclay bricks, compacted and melted with the upper fuse for 25-40 minutes.

After the melting is completed, the melt is aged 40-50 minutes and partially slag is released from the crucible ice.

The disadvantage of this method

The technology does not provide the extraction of molybdenum into metal more than 95%.

The technical result of this invention is to increase the extraction of molybdenum into metal and improve the quality of the alloy.

The technical result is achieved by the proposed aluminothermic method for producing ferromolybdenum, which includes the stepwise loading and smelting of a mixture containing molybdenum concentrate, iron oxide, iron sheathing, lime, ferromolybdenum slag, aluminum and separation of metal and slag.

In the first stage

The mixture is loaded and melted out of the furnace by an aluminothermic method at a speed of 680-850 kg / m ² · min, containing molybdenum concentrate, ferromolybdenum slag, iron sheathing, 65-75% of iron oxide from its weight for melting, 90-95% of its weight smelting and aluminum in the amount of 0.98-1.0 of the stoichiometrically necessary for the restoration of ferromolybdenum alloy elements.

In the second stage

Download and melt the mixture in an out-of-furnace aluminothermic method with a speed of 105-125 kg / m ² · min, containing 25-35% of iron scale from its mass for melting, 5-10% of lime from its mass for melting and aluminum in an amount of 2.6- 3.0% of the stoichiometrically necessary for the restoration of ferromolybdenum alloy elements and the melt is heated in an electric furnace for 3-5 times the charge is melted.

Example 1 (prototype)

Ferromolybdenum was smelted under industrial conditions by a silicoaluminothermic process with an upper fuse in a replaceable melting crucible lined with fireclay brick.

A mixture of the composition was loaded and melted into the crucible at a speed of 198 kg / m ² · min: molybdenum concentrate - 4200 kg, iron ore - 756 kg, iron sheathing - 966 kg, 75% ferrosilicon - 1260 kg, secondary aluminum - 294 kg, lime - 126 kg and fluorspar - 126 kg. After the charge was melted, the melt was held in the crucible for 45 minutes and the slag was partially drained from the crucible into the mold.

Extraction of molybdenum into the metal was 94.98%; ferromolybdenum grade FeMo 58 (n.c.) was obtained.

The proposed method of aluminothermic production of ferromolybdenum was tested under industrial conditions in a melting crucible lined with chamotte and magnesite brick according to the described technology. The results of the heats of the known method (prototype 1) and the proposed (examples 2-6) are shown in table 1.

Example 2

In the melting crucible, the stage loading and melting of the charge by an out-of-furnace aluminothermic method was carried out.

In the first stage

The charge was loaded and melted at a loading speed of 800 kg / m ² · min of composition: molybdenum oxide - 1000 kg, iron oxide - 168 kg, iron sheathing - 230 kg, lime - 190 kg, primary aluminum - 446 kg and ferromolybdenum slag - 817 kg .

In the second stage

The charge was loaded and melted at a loading speed of 110 kg / m ² · min of composition: iron oxide - 60 kg, lime - 10 kg and primary aluminum - 47 kg.

After the charge was melted, the melt was heated under the arcs of the electric furnace for 14 minutes.

The extraction of molybdenum into the metal was 99.1%; ferromolybdenum of the FeMo 60 grade was obtained (n.a.).

Example 3

In the melting crucible, the stage loading and melting of the charge by an out-of-furnace aluminothermic method was carried out.

In the first stage

The charge was loaded and melted with a loading speed of 780 kg / m ² · min of composition: molybdenum concentrate - 1000 kg, iron oxide - 168 kg, iron sheathing - 146 kg, lime - 190 kg, primary aluminum - 415 kg, ferromolybdenum slag - 744 kg .

In the second stage

The charge was loaded and melted with a loading speed of 120 kg / m ² · min of composition: iron oxide - 60 kg, lime - 10 kg and primary aluminum - 45 kg.

After the charge was melted, the melt was heated under the arcs of the electric furnace for 15 minutes.

Extraction of molybdenum into the metal was 99.0%; ferromolybdenum grade FeMo 60 (n.c.) was obtained.

Example 4

In the melting crucible, the stage loading and melting of the charge by an out-of-furnace aluminothermic method was carried out.

In the first stage

The charge was loaded and melted at a loading speed of 785 kg / m ² · min of composition: molybdenum concentrate - 1000 kg, iron oxide - 168 kg, iron sheathing - 125 kg, lime - 190 kg, primary aluminum - 390 kg and ferromolybdenum slag - 635 kg .

In the second stage

The charge was loaded and melted with a loading speed of 125 kg / m ² · min of composition: iron oxide - 60 kg, lime - 10 kg and primary aluminum - 45 kg.

After the charge was melted, the melt was heated under the arcs of an electric furnace for 12 minutes.

Extraction of molybdenum into the metal was 98.6%; ferromolybdenum grade FeMo 60 was obtained.

Example 5

In the melting crucible, the stage loading and melting of the charge by an out-of-furnace aluminothermic method was carried out.

In the first stage

The charge was loaded and melted at a loading speed of 880 kg / m ² · min of composition: molybdenum concentrate - 1000 kg, iron oxide - 168 kg, iron sheathing - 169 kg, lime - 190 kg, primary aluminum - 384 kg and ferromolybdenum slag - 442 kg .

In the second stage

The charge was loaded and melted with a loading speed of 123 kg / m ² · min of composition: iron oxide - 60 kg, lime - 10 kg and primary aluminum - 45 kg.

After the charge was melted, the melt was heated under the arcs of an electric furnace for 11 minutes.

Extraction of molybdenum to metal amounted to 97.3%. The decrease in extraction is associated with the rapid course of the process and emissions of the melt. Received ferromolybdenum grade FeMo 58 (NK).

Example 6

In the melting crucible, the stage loading and melting of the charge by an out-of-furnace aluminothermic method was carried out.

In the first stage

The charge was loaded and melted at a loading speed of 650 kg / m ² · min of composition: molybdenum concentrate - 1000 kg, iron oxide - 130 kg, iron sheathing - 150 kg, lime - 180 kg, primary aluminum - 362 kg and ferromolybdenum slag - 649 kg .

In the second stage

The charge was loaded and melted with a loading speed of 105 kg / m ² · min of composition: iron oxide - 68 kg, lime - 18 kg, primary aluminum - 49 kg.

After the charge was melted, the melt was heated under the arcs of an electric furnace for 10 minutes.

Extraction of molybdenum into the metal amounted to 97.7%. The reduction in recovery is associated with a slower process of smelting and an increased escape of the charge and evaporation of molybdenum oxide. Received ferromolybdenum grade FeMo 58.

Swimming trunks (examples 2-4 and 6) proceeded calmly. After the second stage of the charge was melted and heated on the surface of the melt in the crucible, “KIP” was observed as a result of the deep reduction of the residual molybdenum oxides in the slag melt and the deposition of metal kings from the slag. The obtained standard ferromolybdenum grades: FeMo 60, FeMo 60 (n.k.), FeMo 58, FeMo 58 (n.k.).

Extraction of molybdenum in swimming trunks was 97.3-99.1%.

The technological difference of the proposed method from the known one lies in the fact that the use of aluminum as a reducing agent increased the completeness of the flow of the smelting reduction processes and the rate of charge penetration, while the molybdenum-containing charge (dust) and molybdenum oxide fumes decreased.

The rational distribution of the charge components by the melting stages in the first stage ensured the optimal specific heat of the process 17-19 kcal / g-at and a high charge penetration rate of 650-850 kg / m ² · min without melt emissions with minimal heat loss due to the introduction of the charge into the composition ferromolybdenum slag as a ballast additive, which was decisive for maintaining the optimum temperature of aluminothermic smelting of ferromolybdenum and conditions for the reduction of molybdenum. When using ferromolybdenum slag with a high content of molybdenum oxides, molybdenum oxides are re-reduced when the charge is melted at the second stage of melting and further heating of the slag melt. The use of aluminum in the charge in the amount of 0.98-1.0 of the stoichiometrically necessary for the reduction of ferromolybdenum alloy elements reduces the transition of silicon into the alloy. In this case, silicon oxides bind with calcium oxides present in the charge, in a strong connection. An excessive concentration of reduced oxides with respect to the reducing agent increases the conditions for the efficient use of aluminum in the first stage of smelting.

At the second stage, the melting of a charge with an amount of aluminum of 2.6-3.0 from the stoichiometrically necessary for the reduction of alloy elements and subsequent heating of the slag melt provides a deep re-reduction of molybdenum oxides in the slag melt, the deposition of metal kings and increases the conditions for the efficient use of aluminum.

When using a number of technological methods in the proposed method of aluminothermic production of ferromolybdenum, a complete separation of metal from slag was achieved and a pure metal ingot was obtained, which made it possible to sharply reduce metal losses with crumb, marked skull plates and the bottom of the melting crucible.

According to the proposed method, the extraction of molybdenum into the metal was 97.3-99.1%, which is 2.3-4.1% higher than the extraction by the known method.

Claims (1)

A method for aluminothermally producing ferromolybdenum, comprising the stepwise loading and melting of a mixture containing molybdenum concentrate, iron oxide, iron sheathing, lime, ferromolybdenum slag, aluminum and separation of metal and slag, characterized in that at the first stage the charge is loaded at a speed of 680-850 kg / m ² min, containing molybdenum concentrate, ferromolybdenum slag, iron sheathing, 90-95% lime from its mass for melting, 65-75% iron oxide from its mass for melting, and aluminum in the amount of 0.98-1.0 from stoichiometrically necessary required to restore the elements of the ferromolybdenum alloy, and in the second stage load the mixture at a speed of 105-125 kg / m ² min, containing 25-35% of iron oxide from its mass for smelting, 5-10% of lime from its mass for smelting and aluminum in the amount of 2.6-3.0 from the stoichiometrically necessary for the restoration of the elements of the ferromolybdenum alloy and melt is heated in an electric furnace for 3-5 times the charge is melted.