RU2238995C2 - Method of preparing ferroniobium by out-of furnace reductive smelting - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: preparation of ferroniobium from niobium pentoxide involves preparation of charge, loading of charge, smelting, and reduction of niobium and iron oxides with aluminum powder. Charge is loaded layerwise into crucible alternatively with loading of slag from preceding smeltings ground to the same particle size as that of the charge and used in amount 6-8% on the weight of the charge.

EFFECT: improved ferroniobium preparation technology.

3 cl, 2 ex

Description

The invention relates to the field of metallurgy of rare metals and alloys, in particular to the production of ferroniobium from niobium pentoxide.

A known method of producing ferroniobium grades NBOF-0, NBOF-1, NBOF-2, having a low content of sulfur (0.03-0.1%) and phosphorus (0.08-0.12%), which consists in carefully mixed batch consisting of niobium pentoxide, aluminum powder, iron ore (in the form of crushed pellets or dross) and lime, taken in the amount of 55-65% of the required niobium content in ferroniobium, is loaded into a cast-iron split shaft with a diameter of 1.6 m, lined magnesite brick. To initiate the beginning of recovery, a mine is used with both the upper and lower fuses. Melting is carried out at a temperature of about 2000 ° C for 6-8 minutes. The resulting alloy is poured into a mold, consisting of a cast-iron ring and a block of metallic chromium 200-300 mm thick (M. A. Ryss “Production of Ferroalloys”).

The disadvantage of this method is the lack of a method for additional purification of the recoverable charge with a high content of sulfur and phosphorus in niobium pentoxide, which pollute the resulting ferroniobium. Another disadvantage of the prototype is the low productivity associated with the time spent on the lining and refining of the cast-iron mine with magnesite brick. It should also take into account the consumption of expensive materials: magnesite brick and metallic chrome for the mold.

The objective of the present invention is to develop a method for producing ferroniobium with a low content of sulfur and phosphorus from niobium pentoxide with a high content of sulfur and phosphorus.

The technical result of the proposed method is to reduce in the resulting ferroniobium sulfur content by about 50%, phosphorus by 20-30%.

The essence of the invention lies in the fact that, in contrast to the known method for producing ferroniobium by secondary furnace smelting, including the preparation of a charge, its loading, smelting and reduction of niobium and iron oxides with aluminum powder, according to the proposed method, the charge is loaded layer by layer into a crucible, alternating it with crushed particles charge slag from previous heats in an amount of up to 6-8% of the weight of the charge.

In contrast to the prototype, the extra-furnace recovery of niobium pentoxide is proposed to be carried out in thick-walled collapsible copper crucibles, consisting of 4 parts: 3 rings and a massive bottom; or in a thin-walled copper collapsible water-cooled crucible. In contrast to the cast iron mine, there is no need to lining the crucibles with magnesite bricks and to use metal chrome for the molds, since a stainless steel tray is used to receive ferroniobium and slag.

EXAMPLE 1

There are niobium-containing materials having a high content of sulfur and phosphorus (> 0.1% and> 0.12%, respectively) that are not removed by conventional hydrometallurgical methods in further process chains. Therefore, at the batch preparation site, a mixture of the following composition was prepared: Nb ₂ O ₅ —39.6%; P ₂ O ₅ - 0.25%; S - 0.32%; Al (powder) 23.3%; Fe ₂ O ₃ - 22% (crushed iron ore pellets), CaO - 11.8%; CaF ₂ - 3.2%. The mixture, thoroughly mixed in a body mixer, was loaded into a thick-walled collapsible copper crucible. The mixture was interspersed with layers of crushed slag from previous heats in the amount of 6-8% of the weight of the mixture. The excess of the reducing agent was 5% of the theoretically necessary for the reduction of oxides of niobium, tantalum, iron, etc. Melting in a crucible was carried out at a temperature of about 2000 ° C for 0.8-1.5 min. The obtained ferroniobium contained Nb - 63%, S - 0.007%, P - 0.088%.

EXAMPLE 2

At the batch preparation site, a mixture of the following composition was prepared: Nb ₂ O ₅ —39.6%; P ₂ O ₅ - 0.25%; S - 0.32%; Al (powder) - 23.3%; Fe ₂ O ₃ - 22%; CaO - 11.8%; CaF ₂ - 3.2%. The mixture, thoroughly mixed in a body mixer, was fed into a thin-walled copper water-cooled crucible. The mixture was interspersed with layers of crushed slag of the previous heat in the amount of 6-8% of the weight of the mixture. The obtained ferroniobium contained Nb - 64%; S - 0.02%; P - 0.074%. Thus, the use of slag from previous melts in an amount of 6-8% of the weight of the charge significantly improves the purification of ferroniobium from sulfur and phosphorus.

Sources of information

1. N.P. Lyakishev, Yu.L. Pliner, G.F. Ignatenko, S.I. Lappo. Aluminothermy.

2. M.A. Ryss. Ferroalloy production.

Claims (3)

1. A method of producing ferroniobium out-of-furnace reduction smelting, including the preparation of a charge, its loading, smelting and reduction of niobium and iron oxides with aluminum powder, characterized in that the charge is loaded layer by layer into a crucible, alternating it with crushed to the size of the charge slag from previous melts in an amount up to 6-8% of the weight of the charge. 2. The method according to claim 1, characterized in that the smelting is carried out in massive thick-walled collapsible copper crucibles, consisting of 4 parts. 3. The method according to claim 1, characterized in that the melting is carried out in a copper thin-walled collapsible water-cooled crucible.