RU2374350C1 - Method of combined processing of oxided and carbonate ferromanganese ores - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to the ferrous metallurgy field, particularly to manufacturing of ferroalloys, particularly to creation of methods of combined processing of oxided and carbonate ferromanganese ores with receiving of manganese ferroalloys. Method includes separate preliminary enrichment of mentioned ores with receiving of oxide and carbonate concentrates, fractionating, separation of large and agglomerating of undersize particles, smelting from them low-phosphorus dross (LPD), received from carbonate concentrates, and low-phosphorus dross (LPD), received from oxide concentrate, usage of the latter at smelting of carbonaceous ferro- and silicon manganese, herewith smelting of carbonaceous ferromanganese is implemented by flux-free process with usage in the capacity of crude ore of carbonate concentrates and low-phosphorus dross (LPD) with receiving of charge manganese slag, and melting of silicon manganese is implemented from charge, consisting of charge manganese slag from smelting of carbonaceous ferromanganese, low-phosphorus dross (LPD), quartzite and carbonaceous reducer.

EFFECT: invention provides increasing of through extraction of manganese ensured by sharing of low-phosphorus dross, received from oxide and carbonate manganese concentrates and improvement of ferroalloy quality.

15 tbl, 3 dwg, 2 ex

Description

The invention relates to the field of ferrous metallurgy, in particular to the production of ferroalloys, and in particular to the creation of methods for the joint processing of oxidized and carbonate ferromanganese ores to produce manganese ferroalloys that meet the requirements of current GOSTs and TUs.

Manganese ores of most Russian deposits are poor and phosphorous. They usually require sophisticated enrichment methods, and the presence of a high phosphorus content in them significantly limits the scope of their consumption due to the stringent requirements for the quality of manganese ferroalloys according to this indicator.

Several methods are known from the technical literature related to the search for optimal processing options for poor manganese ores, in particular, ores from the Usinsky and Porozhinsky deposits, which contain elevated concentrations of iron and phosphorus and the use of which does not allow to directly produce standard manganese ferroalloys in one step. Table 1 presents the chemical compositions of manganese ores of the most attractive Russian deposits.

Table 1 Field Content% Mn Fe ₂ O ₃ SiO ₂ CaO MgO P Loss on ignition Usinsk
oxidized ores 24.37 11.8 25.71 2.54 1.15 0.235 13.03 Usinsk
carbonate ores 19.24 7.03 12.70 20.7 0.58 0.152 31.36 Porozhinsky 18,20 6.86 33.1 8.00 1.42 0.57 9.93 Parnock 24.01 3.14 14.5 14.0 2.41 0.05 29.40

When these ores are deeply enriched with gravity and a number of other methods in order to increase the concentration of the leading element, a significant amount of fine-grained concentrates with a particle size of 0 to 5 mm is obtained, which are unsuitable for existing technology for direct use in the production of manganese ferroalloys in electric arc furnaces. They must first be subjected to agglomeration. At the same time, with an increase in the manganese content, a high specific concentration of phosphorus (P / Mn> 0.005) is retained and their dephosphorization is required before smelting manganese ferroalloys. At the same time, high concentrations of silica (above 10%) are present in oxidized manganese ores, and a high basicity (CaO / SiO ₂ ratio> 1) is present in carbonate ores, which also does not allow efficient use of already developed methods for processing these ores (concentrates) . For flux-free melting, it is necessary to have a ratio of phosphorus to manganese in a concentrate of less than 0.0031, and a ratio of iron to manganese less than 0.125.

Table 2 shows the chemical compositions of manganese concentrates obtained by the enrichment of ferromanganese ores of the Usinsky deposit by the X-ray radiometric method.

table 2 Grade of concentrate Content% Mn Fe ₂ O ₃ SiO ₂ CaO MgO P Loss on ignition Carbonate, 1 grade 36.0 4,57 9.49 7.44 1.76 0.16 26.58 Carbonate, grade 2 25,2 4.71 13.32 14.95 2.85 0.15 27,2 Carbonate, grade 3 23.5 7.14 14.17 16.03 3.05 0.14 25.95 Oxide 35.0 15,57 13,20 2,36 1.51 0.22 9.49

(I. Rozhikhina and others. Problems of the use of Kuzbass manganese ores, report at the international conference of ferro-smelters, September 2008, Moscow).

With regard to the compositions of the concentrates presented in table 2, the above relations are not maintained, therefore, new technological approaches are required for their processing.

Various methods (chemical, hydrometallurgical) for dephosphorization and reduction of the iron content in these concentrates are being intensively developed at present, however, their wide involvement in production continues to be a problem that needs to be solved.

From the practice of processing pyrometallurgical methods for their processing that are similar in composition to manganese concentrates, there are two stages:

the first is the removal of phosphorus by melting in an electric furnace with a limited consumption of reducing agent to obtain low-phosphorous manganese slag;

the second is the smelting of ferro- and silicomanganese using the low-phosphorous manganese slag obtained in the first stage.

For example, the Strategic Udi process, in which the production of liquid metal is carried out by two-stage reduction of dusty ferromanganese ores, as well as complex ores with selective extraction of nickel, cobalt, chromium, manganese, phosphorus, iron and titanium. With regard to the processing of poor ferromanganese ores, the known method includes:

- reduction of iron and phosphorus oxides with coal at a temperature of 1100-1250 ° C in a rotary tube furnace;

- receiving container;

- loading the hot charge into a reflective, and then into an arc furnace, where the charge is melted and iron oxides and phosphorus are reduced;

- refinement of liquid low-phosphorous manganese slag to ferro- or silicomanganese in the second electric furnace.

For 1 ton of dry ore (lump size <12.5 mm, manganese content 12-13% and iron 15-20%), 300 kg of limestone and some coal are loaded. During firing, crystallization water and CO _{2 are} removed, and most of the iron is reduced to iron oxide. Hot ore (1000-1200 ° С) is loaded into a reflective furnace, in which the ore-flux mixture is melted at 1350 ° С. The melt is poured into the first electric furnace, in which at 1350 ° C the metallurgical concentration of ore-flux melt is carried out. Slag discharged from the furnace contains 16-17% Mn and 1-2% Fe. Phosphorous cast iron contains 2% C, 0.1% Mn and 3.5% P. In the second electric furnace, carbon ferromanganese or silicomanganese are obtained. In both cases, liquid manganese slag from the first electric furnace is poured into the furnace and a carbonaceous reducing agent is produced with lime in the first case or with quartzite in the second.

The method was proposed by the American engineer M. Yudi in 1955, developed by the companies Statedgic materials corp USA and Anakonda Canada, investigated in Niagara Falls (Canada) at a plant with a capacity of 50 tons per day, including a rotary kiln 24.4 m long and 1.37 m in diameter, reflective and two electric furnaces of 1 mV · A each. Industrial testing of the method was carried out at a plant in Matanzas (Venezuela).

(US patent No. 2342564, priority of 08/15/1957, publ. Volume. 1007, p. 66).

The disadvantages of this method are:

- the complexity of the hardware technology;

- low specific productivity of units;

- difficulties in maintenance associated with the continuous sticking of fine fractions of ore on the walls of a rotary kiln;

- high losses of manganese at each stage of the technological scheme.

There is also known a method of processing poor oxidized manganese ores, including their concentration, fractionation, agglomeration of fine fractions, smelting with a lack of a carbon reducing agent in the mixture to produce low-phosphorous slag and the release of smelting products. Subsequently, the low-phosphorus manganese-containing slag is used for smelting silicomanganese or carbon ferromanganese by the flux process, and the associated alloy is sent to the dump. Malophosphorous manganese slag (IMSF) obtained from oxide concentrates (Table 3), which contains more than 30% silica with a low CaO / SiO ₂ ratio, is usually used in the smelting of silicomanganese (Fig. 1).

Table 3 Product of swimming trunks Content% Mn SiO ₂ CaO MgO P Fe IFFS *. 43.20 30.80 7.60 1,50 0.011 0.23 * - low phosphorus oxide slag.

(M.I. Gasik. Electrometallurgy of manganese. Kiev, publishing house "Technique", 1979, p. 58-68; 119-132).

Silicomanganese is smelted continuously on a charge containing, in addition to low-phosphorus slag, manganese concentrates (their amount in the charge is determined by the requirements for the final phosphorus content in silicomanganese), quartzite and a carbon reducing agent. Analysis of the material balance data for smelting of silicomanganese of the mass grade СМn17 shows that the extraction of manganese from slag into the alloy does not exceed 70%, and that of silicon 35-40% with almost complete (up to 90%) phosphorus transition. The dump slag of silicomanganese has the following chemical composition: 49-52% SiO ₂ ; 12.2-14.5% CaO; 2.9-3.2% MgO; 13.4-15.3% Mn; 0.002-0.003% P; 0.5-0.6% S u 7.2-8.0% Al ₂ O ₃ . The slag ratio is 1.3-1.35. Almost the entire amount of slag from the production of silicomanganese goes to the dump.

It is not economically feasible to use low-phosphorous slag obtained from oxide manganese concentrates for smelting carbon ferromanganese with a flux process because of the need to introduce a significant amount of lime into the charge to bind silica to strong calcium silicates

(2CaO-SiO ₂ ), which additionally leads to an increase in the multiplicity of slag and, as a result, to large losses of manganese with it (up to 30-35%), lower productivity of the electric furnace and increased energy consumption.

The disadvantages of this method are:

- large losses of manganese with final slags due to their high multiplicity and the impossibility of their targeted use in the future;

- low productivity of the electric furnace.

A known method of processing carbonate ores into phosphoric manganese slag, followed by its use for smelting ferromanganese.

(Proceedings of higher educational institutions. Ferrous metallurgy, No. 4, 1967, pp. 55-59).

A method of processing carbonate manganese concentrates to obtain carbon ferromanganese is presented in figure 2.

Smelting of carbon ferromanganese is carried out by a continuous process with a closed top on a mixture of malophosphorous slag (table 4) and calcined carbonate concentrate (34.8% Mn; 9.25% Fe; 0.314% P; 17.0% SiO ₂ ; 12.2% CaO ) Coxic was used as a reducing agent, and limestone was used as a flux. Additionally, wood shavings were introduced into the mixture.

Table 4 Product of swimming trunks Content% Mn SiO ₂ CaO MgO P Fe IFSC * 36.8 23.5 15.17 5.7 0,03 0.33 * - low phosphorus carbonate slag.

The ratio between the low-phosphorus slag carbonate concentrate in the charge was maintained at 50:50.

The obtained metal composition: 77-79% Mn; 0.3-0.6% Si; 0.33-0.36% P; 6.5-7.0% C. Extraction of manganese - 67-77%. The slag ratio is 1.9-2.05.

Raw material consumption per 1 ton (base), kg:

carbonate concentrate 1295 low phosphorus slag 1420 coke 430 limestone 580 dolomite 200 wood shavings 105

This information was taken by us as the closest prototype source.

The disadvantages of the prototype method of processing carbonate manganese concentrates to obtain carbon ferromanganese are:

- low through extraction of manganese in the metal;

- high slag ratio;

- low productivity.

The technical result of the invention is to increase the through extraction of manganese due to the joint use of low-phosphorous slag obtained from oxide and carbonate manganese concentrates, and improving the quality of ferroalloys.

The specified technical result is achieved by that. that in a method for the joint processing of oxidized and carbonate ferromanganese ores with a high phosphorus content, including separate preliminary enrichment of the said ores with the production of oxide and carbonate concentrates, fractionation, separation of coarse and fine-graining, smelting of low-phosphorous slag (MFC) obtained from carbonate concentrates , and low-phosphorus slag (IFSO) obtained from oxide concentrate, the use of the latter in the smelting of carbon ferro- and silicomanganese, The taste of carbon ferromanganese is carried out by a flux-free process using carbonate concentrates and low-phosphorous slag (MFSO) as ore raw materials to produce redistributed manganese slag, and silicomanganese is smelted from a mixture consisting of redistributed manganese slag from smelting of carbon-ferromanganese-ferrous manganese and carbon reducing agent.

The essence of the invention lies in the fact that the smelting of carbon ferromanganese is carried out not by a flux process, as is traditionally done on low-quality raw materials using low-phosphorous manganese slag, but by flux-free to produce tail slag. To obtain a manganese content in the conversion slag within the range of 27-30%, it is proposed to smelter carbon ferromanganese using flux-free technology to produce low-phosphorous slag (MSCF) with 47-49% Mn, which can only be obtained using manganese oxide concentrate.

Figure 3 presents the proposed scheme of a method for the joint processing of oxidized and carbonate ores, including the operations of enrichment, fractionation, sintering with obtaining from them with the help of an electric redistributor first two compositions of low-phosphorous slags (MFShO and MFShK), and then using them at the end of the method of two commodity products:

- carbon ferromanganese;

- commodity silicomanganese.

Oxide and carbonate manganese concentrates without preliminary drying and roasting were used as ore raw materials for smelting low phosphorus slag. Chemical analysis of the concentrates is presented in table 2.

During the smelting of low-phosphorous slag, a small amount of quartzite was additionally introduced into the mixture (to ensure good slag liquid mobility and improve its phosphorus quality). For IMSF - 6.5%, for IMSF - 14.5% of the weight of the ore part. Coke was used as a carbon reducing agent.

Tables 5 and 6 show the chemical compositions of low-phosphorous slag and the resulting alloy. Slag was used in the smelting of manganese ferroalloys. Associated alloy was stockpiled.

Table 5 Product of swimming trunks Content% Mn SiO ₂ CaO MgO P Fe IFES 47.76 27.5 4.8 2.45 0.02 0.63 Content% Mn Si P FROM Fe S Associated alloy 21.8 1,0 1.46 4.0 66.5 0,03

Table 6 Product of swimming trunks Content% Mn SiO ₂ CaO MgO P Fe IFSHK 29.36 34,20 20.72 4.0 0.02 0.43 Content% Mn Si P FROM Fe S Associated alloy 20.38 1,0 2,34 4.0 72.59 0,03

Carbon ferromanganese (figure 3)

In the smelting of carbon ferromanganese, the following concentrates were used as ore materials: carbonate concentrate of the first grade; grade 2 carbonate concentrate; IFSHO.

The composition of the charge, kg:

 grade 1 carbonate concentrate 1000

 grade 2 carbonate concentrate 921

 IFES 679

 coke 349

 cast iron shavings 25

The prepared mixture through the tubing enters the furnace top. Every 2 hours and 40 minutes, melting products are released into the lined ladle and two slag pans installed in a row.

As a result of melting, two products are obtained:

- carbon ferromanganese;

- Converted manganese slag.

The casting of the alloy is carried out in layers in the floor molds and, after cooling, is sent to the finished product warehouse.

Converted manganese slag (PMSh) after cooling is sent to the slag processing department, where it is crushed to the desired fraction and transferred to the storage hopper for subsequent use in the smelting of silicomanganese.

Specific consumption of materials, kg per 1 base ton:

grade 1 carbonate concentrate (36% Mn) 1383 grade 2 carbonate concentrate (25% Mn) 1273 IFES (47.76% Mn) 938 coke 482 cast iron shavings 40

The yield of manganese slag (28% Mn) is 1649 kg.

Electricity consumption - 5132 kWh / t (determined by calculation).

Extraction of manganese to ferromanganese - 60%.

The conversion of manganese to slag (PMSh) is 36.46%.

The compositions of carbon ferromanganese and smelter are presented in tables 7 and 8.

Table 7 The chemical composition of ferromanganese,% Mn Si FROM R Fe 78.0 1.20 6.47 0.42 13.97

Table 8 The chemical composition of the conversion manganese slag (PMSh),% Mn SiO ₂ CaO MgO Al ₂ O ₃ R 28.0 33.88 20.51 5.07 3.8 0.02

The through extraction of manganese (its useful use) was 96.46% instead of 60-65% according to known technology.

The entire volume of smelted conversion manganese slag (PMSH) was used in the smelting of commercial silicomanganese.

Silicomanganese (figure 3)

In the smelting of silicomanganese, the following carbonate concentrates were used as ore raw materials: carbonate concentrate of the 2nd grade; 3rd grade carbonate concentrate; Converted Manganese Slag (PMSh); IFSHK.

Quartzite was used as a silica-containing raw material, and coke was used as a reducing agent.

The composition of the charge, kg:

 grade 2 carbonate concentrate  1000  grade 3 carbonate concentrate   269  Converted Manganese Slag (PMSh)   598  IFSHK   254  quartzite   362  coke   324

The preparation of the charge, the melting mode, the release and casting of the melting products remained the same as on carbon ferromanganese.

As a result of swimming trunks we get two products: silicomanganese and dump slag.

Molded and chilled silicomanganese poured into the molds is transferred to the finished goods warehouse, where it is crushed, sorted and sent to the consumer.

The waste slag is transferred to the slag processing department and, after crushing and fractionation, is sold to construction organizations.

Specific consumption of materials, kg per 1 base ton:

 grade 2 carbonate concentrate  1580  grade 3 carbonate concentrate   425  Converted Manganese Slag (PMSh)   944  IFSHK   449  quartzite   571  coke   512

Electricity consumption - 6318 kWh / t (determined by calculation);

Manganese extraction - 73.79%.

The chemical compositions of silicomanganese and waste slag are presented in tables 9 and 10, respectively.

Table 9 The chemical composition of silicomanganese,% Mn Si R C Fe 70.97 17.0 0.33 1,62 10.06

Table 10 The chemical composition of waste slag,% Mn SiO ₂ CaO MgO Al ₂ O ₃ Fe 10.0 46.0 29.47 6.18 2.54 0.61

The following are examples of the invention, not excluding others in the scope of the claims.

Example 1

On a two-electrode furnace, experiments were carried out to obtain carbon ferromanganese with a flux-free process from low-phosphorous manganese slag, previously smelted from oxide manganese concentrates (the claimed version) and smelting carbon ferromanganese from the same slag using a flux process (known option). Table 11 shows the averaged chemical compositions of manganese ore from which ferromanganese was smelted.

The experiments were carried out in an ore-thermal electric furnace (100 kVA) in order to obtain indicators of smelting carbon ferromanganese from a new type of raw material.

Table 11 Grade of concentrate Content% Mn Fe ₂ O ₃ SiO ₂ CaO MgO P nnn Carbonate, 1 grade 36.0 4,57 9.49 7.44 1.76 0.16 26.58 Carbonate, grade 2 25,2 4.71 13.32 14.95 2.85 0.15 27,2 IFES 47.50 0.68 28.12 4,55 3.00 0.014 -

As ore materials, a mixture of carbonate concentrates of the first and second grades and malophosphorous slag (IMSF) was used, and coke was used as a reducing agent.

The composition of the charge, kg:

 grade 1 carbonate concentrate  13.8  grade 2 carbonate concentrate  12.7  IFES   9,4  shavings   0.4  coke   4.8

The furnace worked smoothly, the gas distribution along the top was uniform, and the melting electric mode was stable. The weight of the metal from each heat varied from 9.5 to 10.3 kg, and the slag from 15.8 to 17.0 kg. The weighted average chemical composition of metal and slag is presented in table 12 (ferromanganese) and 13 (redistributable manganese slag).

Table 12 Product Content% Mn Si FROM P Fe Carbon Ferromanganese 77.66 1.06 6.65 0.42 rest

Table 13 Product Content% Mn SiO ₂ CaO MgO P Converted Manganese Slag (PMSh) * 27.94 33.02 19.88 5.03 0.018 * - average values for five swimming trunks are given

The extraction of manganese into the metal averaged 60.1%; conversion of manganese to slag - 36.5%. The total useful use of manganese was 96.6%.

Control experiments by a known (flux) method were carried out on the same furnace on a mixture containing IMSF, lime, iron shavings and coke. The maximum rate for the extraction of manganese in ferromanganese is shown on a slag basicity of 1.27 and amounted to 69.8%. Slag with a manganese oxide content of 15.1 (11.6 Mn)% does not find further use due to the low manganese content and is sent to the dump, i.e. over 30% of manganese is lost irreversibly.

Example 2

On a charge consisting of redistributed manganese slag of the composition (table 13), carbonate concentrate of the second grade of the composition (table 11), MFSC composition (table 4), quartzite and coke, in the same furnace experiments were carried out on the smelting of CMn17 silicomanganese.

The composition of the charge, kg:

 conversion manganese slag   9.5  grade 2 carbonate concentrate  20,0  IFSHK   4,5  quartzite   5.7  coke   5.2

5 heats were carried out, 51.1 kg of silicomanganese and 94 kg of dump slag were obtained. The weighted average composition of metal and dump slag is presented in table 14 (silicomanganese) and table 15 (dump slag).

Table 14 Thing Content% Mn Si FROM P Fe Silicomanganese 69.97 17.12 1.70 0.34 Ost.

Table 15 Product Content% Mn SiO ₂ CaO MgO Fe Dump slag 11.02 46.00 28.95 6.22 0.13

Extraction of manganese into the metal ranged from 72.5 to 75.0%. The metal composition met the requirements of GOST 4756-91.

The performed calculations showed that from 9.5 kg of converted manganese slag (see the composition of the charge), additionally 2.8 kg of silicomanganese can be additionally obtained.

The proposed method for the joint processing of oxidized and carbonate ores have significant differences from domestic and foreign analogues, in particular:

- smelting of carbon ferromanganese from malophosphorous slag (MFSO) by flux-free process to produce redistributable manganese slag (PMSH);

- obtaining low-phosphorous slag (MFSK) from carbonate concentrates alone.

According to the proposed method, manganese is lost only with the dump slag of silicomanganese, while by the known method it is lost both with the slag of silicomanganese and with the slag of carbon ferromanganese, that is, its losses are from 30 to 40%.

The invention can be implemented at ferroalloy enterprises or individual workshops specializing in the smelting of ferroalloys with manganese.

The implementation of the invention in industry will allow us to solve the problem of rational use of significant reserves of poor manganese ores, in particular ores of the Usinsky deposit, the processing of which by any other methods is currently not cost-effective.

Claims (1)

A method for the joint processing of oxidized and carbonate ferromanganese ores with a high phosphorus content, including separate preliminary enrichment of the mentioned ores to produce oxide and carbonate concentrates, fractionation, separation of coarse and fine particle sintering, smelting of low-phosphorous slag (MFC) obtained from carbonate concentrates, and malophosphorous slag (MFSO) obtained from oxide concentrate, the use of the latter in the smelting of carbon ferro- and silicomanganese, while smelting of carbon ferromanganese is carried out by a flux-free process using carbonate concentrates and low-phosphorous slag (MFSO) as ore raw materials to produce redistributed manganese slag, and smelting of silicomanganese is carried out from a mixture consisting of redistributed manganese slag from smelting of carbon ferrous manganese-ferromanganese and carbon reducing agent.

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