ISSN 0036�0295, Russian Metallurgy (Metally), Vol. 2010, No. 12, pp. 1145–1147. © Pleiades Publishing, Ltd., 2010.Original Russian Text © V.V. Pavlov, A.G. Pomeshchikov, I.A. Bezrukov, S.N. Malyshev, 2010, published in Elektrometallurgiya, 2010, No. 1, pp. 13–17.

1145

Russian metallurgical enterprises are supplied byRussian manganese alloys in an amount of 200 ths tper year, and other 700 ths t are supplied fromUkraine, Kazakhstan, and the Republic of SouthAfrica. The explored reserves of manganese ores inRussia are at least 148 mln t; however, most of themare poor ores, which are complex for extraction andprocessing. Therefore, the manufacture of commer�cial ferroalloys from these ores using classical pro�cesses can be at the boundary of profitability. A wideuse of the ores of the new deposits requires new tech�nologies, one of which is a process that applies plasmashaft ore smelting furnaces with recirculation of a hotfurnace gas.

Researchers at ZAO NPP EPOC actively developplasma technologies and equipment. Full�scalemockups of plasma furnaces are used to develop newtechnologies of high�efficiency reduction smeltingprocesses, which support technical and economicadvantages and high indices of plasma furnaces in effi�ciency, the metal yield, and the capability of operationwith raw materials. As a result, they designed a shopfor the production of silicomanganese in a plasma fur�nace for the SGMK Corporation in 2006–2008. In2006–2007, they designed and produced a pilotRShPP�1.5I1 plasma shaft ore smelting furnace with apower of 1.5 MW, a capacity of 1.0 t silicomanganese(about 4.5 t melt) per hour, and the first melt producedfrom an ore. This furnace was implemented in 2009. InRussian metallurgy, such a furnace design and a pro�cess of silicomanganese production were used for thefirst time, and they still have no analogs.

We were the first to effect this process and a furnacewith a plasma generator operating under a charge layerin contact with it and cascade arcing on an ore andwithout a bottom electrode. We applied the scheme ofclosed recirculation of a dust hot nonpurified gas sup�plied to the plasma generator by smoke exhausters;this generator has no resource limitations and has agraphite consumable part and a plasma flame shapecontrolled during a heat. The furnace design provides

full use of the chemical and physical energy of a reduc�ing agent during a heat and small gas and dust releaseinto a gas�cleaning system.

The electric furnace is shown in the figure.

The estimated annual output of the SGMK�Feros�plavy enterprise, where the furnace is installed, is45 ths t silicomanganese, and the designed furnace isthe first phase of the project. The entire technologicalsystem, beginning from the extraction of manganeseore (Selezen’ deposit) to its preliminary preparationfor remelting and silicomanganese production, islocated in the south of the Kemerovo region. This out�put is sufficient to fully meet the silicomanganesedemands of the Novokuznetsk and Western Siberiametallurgical works.

Such a miniworks can successfully solve the prob�lem of ferroalloy production for any large metallurgi�cal enterprise. The miniworks will be substantiallysmaller and more efficient than a conventional fer�roalloy enterprise.

The leading world technological companies in thefield of metallurgy study the processes and plants thatcan reduce metals from ores using metallurgical pro�cesses in a furnace. The well�known processes are theOxiCap process in a shaft furnace using briquettes andgas burners, the Midrex process, reduction in an openor closed electric arc ore smelting furnace, and others[1–5].

Reduction in most processes is performed usingcarbon�containing materials, e.g., coke and coal(including monocharge, briquettes, or siner), as areducing agent. Hydrogen produced from water ornatural gas is often used in the reduction.

Some technological processes are carried out in asolid phase without a melt (Midrex process). In someprocesses (e.g., OxiCap), solid�phase reduction is per�formed with subsequent melting of the forming materi�als and other metallurgical processes in a liquid phase(reduction, fragmentation of carbides, and so on).

Next�Generation Plasma Shaft Ore Smelting FurnaceV. V. Pavlov, A. G. Pomeshchikov, I. A. Bezrukov, and S. N. Malyshev

SGMK�GruppNGTU

ZAO NPP EPOC

Abstract—A 1.5�W plasma shaft ore smelting furnace designed at NPP EPOS and intended for the produc�tion of silicomanganese in the SGMK�ferrosplavy enterprise is described.

DOI: 10.1134/S0036029510120153

CASTING AND SOLIDIFICATION OF METAL

1146

RUSSIAN METALLURGY (METALLY) Vol. 2010 No. 12

PAVLOV et al.

When comparing various furnace design versions,we conclude that shaft furnaces have substantialadvantages as prototypes of future powerful electricthermal plants for reduction processes.

The advantages of shaft furnaces consist in creatingconditions for reduction processes in a solid phase.This results in additional possibilities of energy savingby regenerating the heat of waste gases in heating ofsupplied raw materials, saving of the initial raw mate�rials, decreasing the losses with dust and gases, and fullusing of the chemical energy of gases. It was experi�mentally supported that plasma operating in a properfurnace zone can increase the extraction of usefulcomponents from ore up to 90–95% of the initial con�tent. This makes the shaft process of reduction prom�ising in the field of processing of ores and the utiliza�tion of industrial wastes.

As compared to furnaces of other types (blast fur�nace, conventional ore smelting furnace, etc.), thedesign of a shaft furnace is characterized by the follow�ing features:

(i) Hydrogen (produced from the vapor and waterof ore materials) and carbon oxide (produced fromcoke during the process) are used as basic reducingagents.

(ii) An “all�sufficient” briquettes, which containan ore material and carbon reducing agent in the pro�portion balanced for full reduction of the ore compo�nents, and possible slag�forming elements are used.The chosen components are in contact with eachother.

(iii) Hot furnace gases are recirculated along theshortest contour and are supplied to a plasma genera�tor and installed gas conduits.

(iv) A high shaft in which drying, preliminary heat�ing, and solid�phase reduction processes take place isused.

(v) A reaction zone of special�purpose geometry isused; a metal and slags melt in it and chemical reac�tions are completed in it.

(vi) The processes occur in the absence of an addi�tional excess oxidizing agent, and a reducing agent isrequired only for reducing reactions and compensat�ing for the losses. The furnace gas at the exit from thefurnace should contain CO2 and H2O.

Problems in the work of plasma furnaces can becaused by an insufficient resource and the technicaldifficulty and relatively low efficiency of metallurgicalplasma generators. Therefore, these problems havereceived most study. We designed simple and reliableplasma units, including coaxial units with a controlledplasma flame shape and graphite electrodes. Theyhave an efficiency more than 97%, have no resourcelimitations, are not afraid of contact with a charge, donot contaminate a melt with copper and other materi�als, and provide a continuous operation of a furnaceover the entire campaign up to preventive mainte�nance [6].

To perform a successful technological process inany furnace unit, metallurgists should properly pre�pare charge materials [7–9]. This means accurate dos�age of charge components, the repeatability of a frac�tion composition, good mixing of charge components,

RShPP�15I1 electric furnace plant designed at ZAO NPP EPOS.

RUSSIAN METALLURGY (METALLY) Vol. 2010 No. 12

NEXT�GENERATION PLASMA SHAFT ORE SMELTING FURNACE 1147

homogeneous chemical composition, sintering, bri�quetting, high (cold and hot) strength of briquettedcharge components, gas permeability, open and closeporosity, and some other measures required for aproper charge preparation.

Insufficient attention to this problem makes theprocess impossible or, at least, inefficient.

When developing the process of a heat, prominencewas given to the quality of applied briquettes. A bri�quette must have a mechanical strength, be resistant tocracking in the cold and hot states (by choosing chargecomponents and production conditions), and retain itsstrength to reaching the required position in a furnace.Our experiments performed on mockups of shaftplasma furnaces demonstrate that the residence time ofbriquettes from charging to melting is 90–100 min,which agrees with the data in [1–4, 10]. The residencetime of briquettes in the working zone with the temper�ature range 1000–1450°C should be 20 min.

The gas permeability of a briquette should be suffi�cient for reactions to occur throughout the entire vol�ume in the time of going through the reduction zone.Under high plasticity conditions, briquette poresshould not be closed and briquettes should not coa�lesce to form a gas�dense conglomerate in a furnace,thus terminating the gas permeability of the chargeand gas recirculation.

A briquette should have a properly chosen compo�sition with a certain given fraction composition ofcomponents, since it is difficult to correct the compo�sition during a heat.

Unsatisfied requirements, a violation of the processof production, and a deviation from the chemicalcomposition of briquettes can strongly decrease thetechnical�and�economic indices of furnace operationand even make the process impossible in some cases(as was shown experimentally). Therefore, the prob�lem of producing briquettes of the required quality isone of the most important problems, and the solutionto this problem in combination with heat conditions isone of the most important “know�how” in designing atechnology and shaft furnaces.

When developing a heat in mockups of a shaft fur�nace, we used iron–coal briquettes containing up to48% iron and silicomanganese briquettes with up to24% manganese, 20% silicon, and 8% iron. We devel�oped the processes of charging raw materials, reachingsteady�state furnace operation conditions, melting ofa briquette, and pouring of a melt with continuousfeeding of a charge through a dosing charging system.When optimizing the charge composition of materials,we melted briquettes of two types in furnace mockupsand made cast iron and ferroalloys.

Commercial silicomanganese has not been pro�duced from briquettes of the manganese ore from theSelezen’ deposit because of the low initial manganesecontent in the ore; nevertheless, the product made inexperimental heats can be applied as a master alloy forsteelmaking.

In cooperation with the Electric Technology Cen�ter of NGTU, ZAO NPP EPOC used pilot experi�mental plasma shaft ore reduction furnaces to performa series of works to improve the process and to opti�mize the chemical composition of briquettes. As aresult, a technology was developed for a plasma shaftore reduction furnace, and a furnace design wasobtained for a high�efficiency production of silico�manganese and some other alloys.

The results of these works will be used in the pilotexperimental RShPP�15I1 furnace during its imple�mentation.

In 2009, this furnace received a positive report ofcommercial safety examination.

REFERENCES

1. “Recovery of Iron from Wastes Using the OxiCap Pro�cess,” Metallurgicheskoe Proizvodstvo i Tekhnologiya,No. 1, 15–24 (2006).

2. A. N. Tulin et al., Development of Coke�free Metallurgy(Metallurgiya, Moscow, 1987) [in Russian].

3. V. F. Knyazev, Coke�Free Metallurgy of Iron (Metal�lurgiya, Moscow, 1972) [in Russian].

4. O. V. Polokhin and S. A. Kutsenko, “Basic Trends inthe Development of Coke�free Metallurgy,” in Trans�actions of Scientists from the Orlov Region (Orlov, 1998),pp. 286–291.

5. Technology of Semiconductor Silicon. Ed. byE. S. Fal’kevich, E. O. Pul’ner, I. F. Chervonyi, et al.(Metallurgiya, Moscow, 1992) [in Russian].

6. “Method of a Heat and Related Plant,” RF Patent2361375, 2007.

7. S. I. Popov, Metallurgy of Silicon in Three�Phase OreSmelting Furnaces (IPO BRUEP, Irkutsk, 2004)[in Russian].

8. N. V. Tolstoguzov, Theoretical Foundations of theReduction of Manganese, Silicon, and Impurities duringMaking of Ferromanganese and Silicomanganese:A Tutorial (SMI, Novokuznetsk, 1991).

9. I. A. Bezrukov and A. G. Pomeshchikov, “NewDesigned Projects of NPP EPOS,” Elektrometal�lurgiya, No. 7, 46 (2008).

10. V. P. Vorob’ev, V. I. Lapchenkov, and A. V. Igant’ev,“Methods for an Efficient Use of the Energy of GasesReleased from Shaft Ferroalloy Furnaces,” Elektro�metallurgiya, No. 6, 39–43 (2008).