RU2714561C1 - Method of producing ferrosilicon in closed ore-thermal furnaces - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, particularly to an electrothermal method of producing ferrosilicon. Ferrosilicon in closed ore-reducing electric furnaces is obtained by reducing quartzite with the help of carbon reducing agents in the presence of steel chips. Directly under furnace roof between electrodes charge is additionally consisting of quartzite, steel chips with carbonaceous reducing agent exceeding stoichiometric amount by 2–8 wt%, with periodicity of single loading in 16–24 hours, at that amount of charged charge into furnace with increased excess of carbon reducing agent makes 4–10 % of total amount of loaded charge.

EFFECT: invention reduces downtime for cleaning sub-water space and gas intake branch pipes.

1 cl, 1 tbl, 4 ex

Description

Technical field

The invention relates to the field of metallurgy, in particular to an electrothermal method for producing ferrosilicon.

State of the art

Ferrosilicon in closed furnaces of ore-reducing electric furnaces is obtained by reducing quartzite using carbonaceous reducing agents (Rozhikhina I.D., Nokhrina O.I. Fundamentals of the theory and technology of production of ferroalloys, SibGIU, Novokuznetsk, 2017, P. 85-89). The disadvantages of this technology is the insufficient productivity of the furnaces.

The prior art method for smelting ferrosilicon (patent RU 2112071, C22C 33/04, publ. 1998.05.27), comprising continuously feeding a metered charge formed in the form of cones around electrodes containing ore part and as a reducing agent coke, melting the charge and periodic metal production, characterized in that, before the next metal production, the charge cone is melted and the silicon-containing pellets of the spent contact mass of chemical production are set in portions 10-15 minutes before the next metal production. Disadvantage

A known method of smelting ferrosilicon alloys (patent RU 2294977 C22C 33/04, publ. 1997.03.10) with a silicon content of 60-70% in a three-phase ore-thermal electric furnace with coal lining of the walls, including loading into the furnace of the original charge materials containing silica, steel shavings and carbon reducing agents, characterized in that the charge is loaded into the furnace differentially, while in three zones of the top, located radially in areas corresponding to the minimum gap between the electrodes and the lining of the walls and a width of 0.7-1.2 diameters of electro and fed batch with silica content of 70-100% by weight. Disadvantage

A known method of smelting fecrosilicon (patent RU 2059013, C22C 33/04, publ. 1996.04.27), including continuous loading around the electrodes of the mixture, consisting of quartzite, coke, reducing agent and iron shavings, its melting and periodic release from the furnace alloy into the bucket, characterized in that around the electrodes load part of the charge containing iron chips 0.5 0.6 stoichiometric flow rate and 2.5 times higher than the flow rate of the Central zone of the furnace, and the other part of the charge containing iron chips 2 to 3 times more stoichiometric flow rate load the central zone of the furnace. Disadvantage

The prior art method for smelting ferrosilicon in closed ore-thermal furnaces (patent RU 2059011, С22С 33/00, publ. 1996.04.27), including loading into the furnace through the arch of a mixture consisting of quartzite, coke, iron shavings and a reducing agent around the electrodes, its continuous penetration and release of the alloy into the ladle, while part of the charge is loaded through the arch into the central zone of the furnace at a stoichiometric ratio of the flow rate of quartzite and coke, it contains an excess of iron shavings, and part of the charge loaded around the electrodes with a stoichiometric ratio In relation to the consumption of quartzite and a reducing agent, it has a lack of iron chips. In this case, the stoichiometric charge of quartzite and coke loaded around the electrodes contains iron chips of 0.5 to 0.6 stoichiometric flow, and the charge loaded under the arch into the central zone of the furnace contains a 2-3-fold excess of iron chips from stoichiometric flow; and the charge consumption around the electrodes in the amount of 2-4 times the consumption of the charge supplied directly under the arch in the Central zone of the furnace.

By technical nature, by the presence of common features, this technical solution was adopted as the closest analogue of the declared

method of smelting ferrosilicon. The disadvantage of this method is not a sufficiently high degree of extraction of silicon. In addition, increasing the productivity of the furnace due to the implementation of the method does not solve the problem of a closed furnace, periodic sintering of the charge and the formation of condensate under the roof of the ore-thermal furnace. Condensation occurs due to the fact that silicon monoxide, which does not come into contact with the charge carbon, disproportionately reacts

2SiO = Si + SiO ₂ ,

which leads to sintering of the charge on the top surface under the umbrella of the furnace (MA Ryss. Production of ferroalloys, M., Metallurgy 1985, S. 75-77).

The basis of the invention is the task of increasing the technological stability of the furnace.

The technical result is to increase the productivity of the furnace.

Disclosure of Invention

The technical result is achieved due to the fact that a charge consisting of quartzite, reducing agents and steel chips with a reducing agent exceeding the stoichiometric amount by 2-8 masses is periodically loaded under the furnace arch. %; the amount of charge loaded into the furnace with an increased excess of carbon is 4-10% of the total amount of charge loaded, with a periodicity of a single charge loading with a high carbon content of 16-24 hours.

The implementation of the invention

Testing of the method was carried out in an industrial closed ore-thermal furnace with a capacity of 18 MB, operating on smelting ferrosilicon grade FS 65. During the tests, the excess carbon in the charge additionally charged under the arch was changed, the amount of charge periodically charged under the arch of the furnace, the frequency of loading of the additional charge according to arch one times per shift (8 hours). An additional charge was loaded in equal amounts between the electrodes. The test results are summarized in table 1.

According to the achieved best indicator (Example 14), the charge was loaded with an increased excess of carbon with a different frequency: 12, 16, 24, 32 hours.

Experience 1. The frequency of loading once every 12 hours: produced the loading of the mixture with an excess of carbon 6 wt. % in the amount of 10% of the stoichiometric composition of the mixture; the furnace productivity amounted to 2358 kg / h., the specific energy consumption was 7634 kWh / t;

Experience 2. The next test was carried out with a frequency of loading the mixture with an excess of carbon 6 wt. % in the amount of 10% once every 16 hours: the furnace productivity was 2376 kg / h., specific electricity consumption was 7576 kWh / t;

Experience 3. Conducted tests with a frequency of loading the mixture with an excess of carbon 6 wt. % in the amount of 10% once every 24 hours: the furnace productivity was 2368 kg / h, the specific energy consumption was 7600 kWh / t.

Experience 4. Conducted tests with a frequency of loading the mixture with an excess of carbon 6 wt. % in the amount of 10% once every 32 hours: the furnace productivity was 2360 kg / h, the specific energy consumption was 7627 kWh / t.

According to the test results, we can conclude: the best option for changing the excess carbon in the mixture is 2-8 wt. % (examples 2-7, 9-11, 13-15), the amount of charge loaded into the furnace with an increased excess of carbon is 4-10% (examples 4-7, 9-11, 13-15), the optimal frequency of charge loading is one every 16-24 hours (experiments 2-3). When loading an additional charge with an excess of carbon 2 wt. % (examples 2-3), 10-12 wt. % (examples 8,10-12, 20) are not optimal, since a slight increase in excess carbon does not change the technological mode of operation of the furnace; an increase in excess carbon more than 10 wt. %, leads to violations of the technological regime and the productivity of the furnace is reduced. When loading a mixture with an increased excess of carbon, the optimal frequency of loading the mixture is 16-24 hours. With a frequency of loading a charge with an excess of carbon less than 16 hours, the productivity of the furnace changes slightly, with a frequency of more than 24 hours, the productivity of the furnace decreases.

An additional effect due to the reduction of downtime for cleaning the underwater space and gas inlets.

Information:

1. Rozhikhina I.D., Nokhrina O.I. Fundamentals of the theory and technology of production of ferroalloys, SibGIU, Novokuznetsk, 2017, P.85-89;

2. Patent RU 2112071, publ. 1998.05.27;

3. Patent RU 2294977, publ. 1997.03.10;

4. Patent RU 2059013, publ. 1996.04.27;

5. Patent RU 2059011, publ. 1996.04.27.

Claims (1)

A method for smelting ferrosilicon in closed ore-thermal furnaces, including loading a charge consisting of quartzite, a carbon reducing agent and steel shavings taken in a stoichiometric ratio into the furnace through the arch around the electrodes, continuously melting it and releasing the alloy into the ladle, characterized in that it is directly under the furnace arch between the electrodes additionally load a mixture consisting of quartzite, steel shavings with a carbon reducing agent, which exceeds the stoichiometric amount by 2-8 wt.%, with a frequency of howling download additional charge in 16-24 hours, and the amount of the charge loaded into the furnace with a high excess carbon reducing agent is 4-10% of the total amount of the charge loaded.