KR101835708B1 - Method for recovering valuable metals from stainless steelmaking converter slag by Submerged Arc Furnace - Google Patents

Abstract

A method for recovering valuable metals in stainless steel making slag using a melting reduction electric furnace (SAF) is provided.
The method of the present invention, by using a (SAF) a smelting reduction electricity, a method for recovering valuable metals from CaO, SiO _2, Al ₂ O _3, MgO, and stainless steelmaking converter also chromium slag containing Cr ₂ O ₃ (SAF), adding FeO in the range of 2.5 to 50 wt% per 1 tonne of the chromium slag to the above-mentioned Ham Cr-containing slag, Reducing the chromium slag using the amount of carbon in the range satisfying the relationship (3); And the basicity [CaO + MgO) / SiO ₂ ] of the produced slag is controlled in the range of 0.7 to 1.5 after the melting and reduction of the chromium slag.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for recovering valuable metals from stainless steelmaking converter slag by submerged arc furnace using a melt-reduced electric furnace (SAF)

The present invention relates to a method for recovering valuable metals (Cr, Fe) from a chromium-containing stainless steel making steel slag using a submerged arc furnace (SAF).

The oxides containing chromium oxide (Cr ₂ O ₃ ) include chromium (Cr Cr) slag, chromium sludge, and chromium dust, and are produced in the process of producing chromium-containing steels, particularly steelmaking processes. In this specification, this oxide is simply referred to as slag.

If such a slag does not contain chromium, it can be used as a byproduct of steel production, such as roadbed material and concrete aggregate. However, in general, when chromium is in the form of chromium oxide (Cr ₂ O ₃ ) in a condition of 4 wt% or more, the state of chromium in the slag or the state of the chrome eluting to the periphery is changed due to the environmental conditions, Do. That is, the chromium contained in the slag is solidified as an oxide such as chromium oxide or exists as a spinel oxide such as magnesium oxide (MgCr ₂ O ₄ ), etc. In this state, in contact with moisture in the treatment environment Chromium is eluted.

At this time, chromium is eluted into trivalent chromium or hexavalent chromium depending on the form contained in the slag. The hexavalent chromium is a component that should be inhibited from diffusing into the surrounding environment and is designated as a specific harmful substance and strictly controlled. The reason for this is that slag containing 4 wt% or more of chromium oxide is a major reason for recycling. The chrome oxide in the slag monoxide, chromium (CrO), chromium dioxide (Cr ₂ O ₃₎ to exist, wherein chromium is chromium concentration levels obtained by the chemical analysis, that the chromium oxide T.Cr concentration (Cr ₂ O _3, etc. ) In terms of mass percentage (wt%).

Chromium stainless steel contains more than 10% chromium in its constituent characteristics. Since chromium has stronger affinity with oxygen than iron (Fe), chromium oxidation is inevitably involved in a steelmaking process which proceeds at a temperature higher than 1500 ° C. Also, in the case of an arc electric furnace, since oxygen is essentially taken in order to promote dissolution of scrap, a large amount of chromium is inevitably oxidized and slagged when stainless steel is manufactured.

The amount of chromium oxide in the slag produced as a byproduct in the production of stainless steels using electric furnaces is as high as about 5% to 30%. Therefore, it is general to reduce the chromium oxide in the slag to molten steel by adding a reducing agent such as iron (Fe-Si) or aluminum to the heat-up period after the ferroalloy and scrap are dissolved in terms of manufacturing cost and effective utilization of resources. However, in the case of silicon iron or aluminum used as the reducing agent, the amount thereof is limited due to its high price, and rather it causes a rise in cost. Therefore, attempts have been made to suppress chromium oxidation during oxygen blowing.

Korean Unexamined Patent Publication No. 2005-0109763 relates to a method for maintaining a high temperature liquid phase advantageous for reduction reaction of a valuable metal by raising the slag temperature by using a coarse burner in recovering valuable metals among the stainless steel slag. Chromium oxidation can be suppressed, but the effect is not significant because of the extra fuel required.

Japanese Unexamined Patent Application Publication No. 2001-316712 discloses a method in which at least one of electric arc furnace electrodes is a hollow electrode and a reducing agent such as aluminum, aluminum dross, carbon or the like is blown through a hollow electrode together with an inert gas to reduce chromium oxide in the slag The method is limited to a general application because a hollow electrode is used. Korean Unexamined Patent Application Publication No. 2000-0021329 discloses a method for recovering valuable metals and slag forming by blowing powdered carbon into an arc furnace. However, the reaction between chromium oxide and carbon is difficult to occur at a low temperature and the reduction rate is low.

Korean Patent Laid-Open Publication No. 1998-047211 relates to a method of recovering chromium from ladle after electric arc tumbling by gas agitation, which is disadvantageous in that the loss of chrome in slag discharged in the tumbling is large. Japanese Unexamined Patent Application Publication No. 2001-234226 discloses a method in which a slag generated in a decarburization refining process of stainless steel is put into a separate ladle in a state of being maintained in a liquid state or a liquid state, Wherein the chromium oxide is reduced. In this method, stainless steel molten steel is decarburized in a refining furnace, and chromium oxide in the slag is reduced to lower the chromium oxide concentration to 4 wt% or less, followed by disposal. Next, an aluminum dross is added as a reducing agent to the discharged slag, and the arc is heated to reduce and recover the chromium. However, this method is difficult to handle due to the use of hot slag, and there is no countermeasure against the MgO component in the slag which makes slag reduction difficult, and furthermore, Al ₂ O ₃ , MgAl ₂ O ₄ , Their chromium solid solution hinders the reduction of chromium oxide, which leads to an increase in the cost of aluminum by deteriorating the unit of aluminum used.

Domestic patent document 10-2006-0136918 is also very similar to the features of the Japanese patent application. Korean Patent Laid-Open No. 10-2006-0136918 discloses a method of recovering chromium from a chromium slag by keeping the slag in a liquid state while injecting a predetermined amount of powdered aluminum dross into the molten steel or satisfying a separate formula. In this method, however, there is no countermeasure against the MgO component in the slag, and Al ₂ O ₃ or MgAl ₂ O ₄ produced by aluminum reduction and the chromium solid solution thereof inhibit chromium reduction, none.

Japanese Unexamined Patent Application, First Publication No. 2003-502504 discloses a method in which chromium slag is charged into an arc furnace and iron scrap or residual dust is used as a charging material to additionally add carbon or silicon, And the chromium oxide is directly reduced to chromium metal by carbon or silicon. However, this method is merely a concept of the known melting process of the chromium slag, and does not provide adequate operating conditions for the treatment of slag containing chromium oxide stably.

In Japanese Laid-Open Patent Application No. 2015-193938, molten metal is put into a dedicated arc electric furnace for melting and reducing treatment, and chromium slag is charged into the furnace. Wherein the carbon (C) and silicon (Si) of the molten metal as a reducing agent, and lowering the viscosity of the slag and the chromium oxide are employed on aluminum oxide using an alkaline metal oxide is Na ₂ O ingredient as a basic oxide to suppress the spinel produced . However, this method was more efficient hagieneun commercial use due to occur preferentially react only with the surface of the liquid slag is very low due to the use of Na ₂ O in the powder-form low density, reduction of the chromium oxide according to the Na ₂ O In basic unit There is a problem that the efficiency is unclear. In addition, since the MgCr ₂ O ₄ -MgAl ₂ O ₄ solid solution, which is generated when the content of MgCr ₂ O ₄ and Al ₂ O ₃ is high, is not available when the content of MgO is high in the slag, usability restriction is accompanied by the slag composition.

Recently, a technique for making chromium stainless steel using a converter instead of an arc furnace for scrap melting has been developed in order to use surplus charcoal generated from an integrated steelworks. However, in the case of manufacturing chromium-molybdenum stainless steel using a converter, ferrochromium is easily oxidized as it dissolves. Therefore, the time required for reduction of chromium oxide is excessive, resulting in a decrease in productivity. In order to reduce the amount of chromium lost by chromium slag, For example, it is necessary to increase the amount of iron (FeSi) and aluminum. In addition, the rate of refractory wear on converter is also higher than that of existing processes, which will inevitably lead to an increase in manufacturing cost.

Accordingly, the present invention has been made to overcome the limitations of the prior art for recovering chrome from the chromium slag produced in the production of chromium stainless steel using the above-described converter, and it is an object of the present invention to provide a method for controlling chromium oxide The present invention also provides a method for recovering valuable metals in stainless steel making slag using a melt-reduced electric furnace (SAF) capable of effectively recovering valuable metals in ham chromium converter slag by optimizing the coke content of the reducing agent.

Further, the technical problems to be solved by the present invention are not limited to the technical problems mentioned above, and other technical problems which are not mentioned can be understood from the following description in order to clearly understand those skilled in the art to which the present invention belongs .

A method for recovering valuable metals from chrome slag made of stainless steel, which comprises CaO, SiO ₂ , Al ₂ O ₃ , MgO and Cr ₂ O ₃ using a melt reduction furnace (SAF)

When operating a melting reduction electric furnace (SAF)

Adding FeO, which satisfies the following relational expression 1-2, to the above-mentioned ham chromium slag in the range of 2.5 to 50 wt% per 1 ton of the chromium slag;

Reducing the chromium slag using the amount of carbon in the range satisfying the following formula 3; And

The present invention relates to a method for recovering valuable metals from chrome slag produced from stainless steel making furnaces, characterized in that the basicity [CaO + MgO) / SiO ₂ ] of the resulting slag is controlled in the range of 0.7 to 1.5 after the melting and reduction of the chromium slag will be.

[Relation 1]

_{FeO = (MgO + Cr 2 O} 3) × 0.15

[Relation 2]

2.5? (MgO + Cr ₂ O ₃ ) x 0.15? 50

[Relation 3]

Where α and β are the proportions of Fe and chromium in the metallic state, respectively, incorporated in the chromium slag, and α and β are in the range of 0.5 to 1.0, respectively. Input T.Fe, Input T.Cr and Input T.Si refer to the total amount of each component per ton of raw slag.

In the present invention, the steelmaking furnace chrome slag contains 5 to 25% of CaO, 15 to 35% of SiO ₂ , 0 to 20% of Al ₂ O ₃ , 5 to 40% of MgO, and Cr ₂ O ₃ : 4 to 40%.

In addition to the coke, at least one of aluminum, silicon, and silicon carbide (SiC) may be used as a reducing agent to reduce the chromium slag.

Further, in the present invention, it is preferable that the completion of the melting and re-casting of the chromium slag is performed at a time point of 30 to 50% of the total capacity of the SAF transformer.

The present invention having the above-mentioned constitution is a slag melting reduction method using SAF for the chromium slag produced in the converter, particularly, the chromium slag generated in the steelmaking process, ) Can be recovered, and the risk of leaching of hexavalent chromium can be effectively removed while the oil-rich component is recycled.

Figure 1 shows a CaO-SiO ₂ -MgO ternary phase diagram.
2 shows a (CaO + MgO) -SiO ₂ -FeO slag melting point lowering of the FeO ratio used in the ternary.

Hereinafter, the present invention will be described.

Existing converter slag is easy to 2CaOSiO ₂ generated due to high basicity (CaO / SiO ₂₎ and 2CaOSiO ₂ is to be accompanied by a volume change in accordance with the phase transformation during the cooling process are easily differentiated as Scheme 1

[Reaction Scheme 1]

However, in order to use converter slag in SAF, it is important to ensure ventilation so that the gas generated during the reduction process is easily discharged, so the amount of powder is limited. For this purpose, in the present invention, the MgO component is increased as compared with the conventional MgO component so that the converter slag is not differentiated. On the other hand, the increase of MgO contributes to the extension of the life of the refractory by controlling the flowability of the converter slag

An example of the main components of the converter slag used in the production of the present invention is shown in Table 1 below in comparison with the conventional slag component.

CaO (wt%) SiO ₂ (wt%) Al ₂ O ₃ (wt%) MgO (wt%) Cr ₂ O ₃ (wt%) FeO (wt%) existing 40 to 60% 15 to 30% 2 to 20% 5 to 20% ~ 3% ~ 5% change 5 to 25% 10 to 35% 0 to 20% 5 to 40% 4 to 40% ~ 5%

More preferably, the steelmaking furnace chrome slag contains 5 to 25% of CaO, 15 to 35% of SiO ₂ , 0 to 20% of Al ₂ O ₃ , 5 to 40% of MgO, Cr ₂ O ₃ : 4 to 40%.

As shown in Table 1, the chromium slag used in the present invention contains Cr in a range of 4 to 40 wt%. In particular, the reason for the target of Cr ₂ O ₃ ≥ 4 wt% is consistent with the minimum level requiring reduction of chromium oxide. As a result, the slag having 4 wt% or more of chromium oxide has a high possibility of eluting hexavalent chromium in contact with water, and when diluting with a chromium-free antistatic agent, the content of Cr ₂ O ₃ in the slag is set to 2 wt% The amount of the slag is excessively increased, which is not economical. On the other hand, the reason why Cr ₂ O ₃ ≤ 40 wt% is 40 wt% is the usual upper limit concentration of the chromium oxide in the slag generated in the steelmaking process, and when it exceeds this, the solid phase rate of the slag increases sharply, As well.

However, as shown in FIG. 1, the slag having the above composition has a high melting point of 2,000 DEG C or more because MgO is high, so it is very difficult to dissolve the slag in the melting reduction furnace (SAF). Therefore, in order to lower the melting point of the slag, the SiO ₂ content in the slag must be increased. However, this increases the amount of slag in the SAF, which hinders the operation efficiency. Also, since the content of chromium oxide is high, there is a high risk of elution of hexavalent chromium in the chromium slag treatment, and therefore, it is necessary to reduce chromium oxide to 4 wt% or less by efficiently reducing it.

On the other hand, slag (chromium slag) containing chromium oxide in terms of chromium oxide in terms of chromium oxide in an amount of 4 wt% or more is particularly preferable as a solid solution of MgCr ₂ O ₄ (hereinafter referred to as chromium Spinel). Therefore, in the case of this type of oxide, it is necessary to control the hexavalent chromium leaching together with efficient recovery of chromium.

If the chromium spinel which is chemically stable in the steelmaking temperature range can secure a sufficient reduction rate, that is, a decomposition rate, the liquid slag may be formed, so that the viscosity of the liquid slag should be low and the movement of the material generated after decomposition must be sufficiently fast. In general, in order to make such a state, CaO ₂ O ₃ slag is controlled to have a proper amount of MgO to make a multi-component liquid phase. However, in slag containing chromium slag, ie, chrome spinel, an increase of MgO promotes the formation of MgCr ₂ O ₄ .

As a means for preventing the formation of hexavalent chromium which is in a peroxidized state while securing the reduction rate of chromium spinel under the above-mentioned conditions, in the present invention, in order to control the viscosity of the slag in the liquid phase and control the solid- The inventors have devised a method of adding available FeO.

As shown in FIG. 2, it can be seen that as the FeO concentration increases in the (CaO + MgO) -SiO ₂ -FeO based slag, the melting point of the slag decreases. This is because MgCr ₂ O ₄ is replaced with FeCr ₂ O ₄ having a lower melting point and viscosity depending on the amount of FeO added depending on the content of MgO, and FeCr ₂ O ₄ is decomposed and reduced at a relatively low temperature. Since Fe is easily reduced, it is possible to recover metal Fe by addition of FeO.

Since the slag produced after SAF is produced for a certain period of time produces MgCr ₂ O ₄ according to the MgO component of the parent slag (ham chrome slag charged as raw material), the amount of MgO charged into the SAF through the slag It is necessary to add the FeO amount corresponding to the amount of FeO.

Specifically, in the present invention, it is preferable to add FeO in the range of 2.5 to 50 wt% satisfying the following relational expression 1-2.

[Relation 1]

_{FeO = (MgO + Cr 2 O} 3) × 0.15

[Relation 2]

2.5? (MgO + Cr ₂ O ₃ ) x 0.15? 50

 In the present invention, the reason why the FeO addition concentration is 2.5 wt% or more is that the effect of lowering the slag melting point and the recovery of the metal component due to the addition of FeO is insignificant in the case of 2.5 wt% or less and 50 wt% , The recovery rate of chromium does not change much, but the cost to produce unit chrome is increased, the Cr is diluted in the product and the quality is low and Fe is high, which is not economical in the steelmaking process.

Further, in the present invention, a commercially available wheat scale may be used instead of FeO. In this case, a value obtained by converting T. Fe contained in the mill scale into FeO can be applied.

Further, in the SAF operation, energy is required for heating, reducing, and melting metal oxides in order to reduce metal oxides by using coke and to obtain a molten metal at a certain temperature or higher. And about 60% of the required energy is the resistance heat of the electric energy supplied through the electrode, and about 40% is the oxidation reaction energy of the coke supplied as the reducing agent.

In the present invention, coke containing 86% of fixed carbon and 12.5% of ash or less can be used as the coke used in SAF.

In the present invention, instead of expensive aluminum and iron (FeSi) as a reducing agent for the chromium slag used in the SAF, a coke which can be industrially abundantly used is used as a carbon source. However, in order to reduce the chromium slag, at least one of aluminum, silicon and silicon carbide (SiC) may be used as a reducing agent in addition to the coke.

Energy required for heating, reduction and melting of the metal components contained in the chromium slag must be sufficiently supplied from the resistance heat and coke through the electrode. The chromium slag is melted and reduced to form the molten metal and the slag. At this time, the amount of carbone (kg / tonne-slag) required in the present invention can be determined by the following relation (3).

[Relation 3]

Where α and β are the proportions of Fe and chromium in the metallic state, respectively, incorporated in the chromium slag, and α and β are in the range of 0.5 to 1.0, respectively. Input T.Fe, Input T.Cr and Input T.Si refer to the total amount of each component per ton of raw slag.

If the required amount of carbon is calculated without reflecting Fe and Cr in the metal chrome slag mixed with metal, excessive increase of Si and C in the product due to excessive carbon loading, decrease in operating efficiency due to rise of electrode, And the like.

On the other hand, the CaO increase is a condition in which the slag composition becomes a 2CaOSiO ₂ saturated region, which is a stable compound at a high temperature, and such a solid phase increase is a condition to be avoided from the viewpoint of viscosity deterioration of the liquid phase. As a substitute for such a basic and positive oxide, fluoride such as fluorite (CaF ₂ ) may be added. However, CaF ₂ addition reacts with SiO ₂ to generate CaO, and therefore the melting point of the liquid slag Higher results can result. There is a possibility of elution of fluorine from the slag, and there is a restriction on the use of the SAF electrode and the noble carbon refractory because of high possibility of erosion.

[Reaction Scheme 2]

The rate of {CaO + MgO) / SiO ₂ } in the slag was estimated to be 0.7 ~ ₂ % in order to smoothly discharge slag after the melt reduction in SAF, since the slag composition is a 2CaOSiO ₂ saturated region, It is necessary to compensate for the insufficient SiO ₂ with silica so as to be added to the electric furnace. In this case it is necessary that the basicity is less than 0.7 or greater than 1.5 when in the solid phase as the liquid component and having a melting point of the slag viscosity produced because proper SiO ₂ component is added up.

Meanwhile, in the present invention, the cumulative power amount required for one tapping needs to be determined at a level of 30 to 50% of the SAF transformer capacity in order to generate sufficient resistance heat in the SAF. When the cumulative electric power at the time of one tapping is less than 30% of the capacity of the transformer, the energy required for melting the chromium slag is not sufficiently supplied and is not melted. When the cumulative electric power is over 50%, excess energy is supplied, Thereby reducing the reduction efficiency.

As described above, the present invention _{CaO 5 ~ 25wt%, SiO 2} 10 ~ 35wt%, Al 2 O 3 0 ~ 20wt%, MgO 5 ~ 40wt%, Cr 2 O 3 4 ~ 40wt% resulting from stainless steelmaking converter (SAF) is used as a reducing agent, and when electric energy is supplied from 30% to 50% of the transformer capacity, By judging that the chromium slag has been completely melted and reduced, the valuable metal in the chromium slag can be effectively recovered.

Hereinafter, the present invention will be described in detail by way of examples.

(Example)

division
Slag composition (wt%) CaO SiO ₂ MgO Al ₂ O ₃ Cr ₂ O ₃ FeO Inventory 1 10.1 25.4 4.8 3.7 10.3 5.0 Inventory 2 10.6 24.9 11.2 4.1 18.5 8.0 Inventory 3 10.3 25.2 22.7 3.8 24.4 10.0 Honorable 4 11.6 25.0 29.8 4.0 28.9 15.0

Stainless steel steel making furnace slag as shown in Table 2 below was prepared. In Table 2, FeO added together with the chromium slag was determined to be in the operating condition within the range of 2.5 to 50 wt% per 1 ton of chromium slag by using the above-mentioned relational expression 1-2 according to the content of MgO and Cr ₂ O ₃ of the chromium slag It is the result of adding and subtracting.

Coke was used as a reducing agent for the chromium slag, and the chromium slag was melted and reduced by SAF with a capacity of 10 MVA. At this time, the amount of coke used is divided into FC (fixed carbon) calculated by applying the above-mentioned Relation Formula 3 so as not to be excess or underexposed, and then the amount converted into dry base is applied, 200kg depending on the operating conditions.

Then, tapping was carried out when SAF was charged with ham chromium slag, coke, quartz, FeO, etc., and the cumulative power added to the SAF was 30% to 50% of the transformer capacity. At this time, SiO ₂ was compensated with SiO ₂ so as to maintain the ratio of basicity {(CaO + MgO) / SiO ₂ } at 0.7 to 1.5 so that tapping slag could be smoothly discharged.

Table 3 shows the compositional components of the chromium slag component obtained from the SAF operation results described above using the slag components shown in Table 2. [

division
Slag composition (wt%) * Slag
basicity CaO SiO ₂ MgO Al ₂ O ₃ Cr ₂ O ₃ FeO Inventory 1 25.7 34.5 9.2 6.7 0.9 1.2 1.01 Inventory 2 25.6 37.2 10.9 10.3 1.1 0.9 0.98 Bill Honor 3 25.6 38.3 22.7 10.5 1.4 1.4 1.26 Honorable 4 23.5 39.5 27.7 9.8 0.9 1.1 1.30

* In Table 3, the basicity is (CaO + MgO) / SiO ₂

As can be seen from Table 1-2, it can be confirmed that chromium oxide is efficiently reduced even when Cr ₂ O ₃ and MgO are high in the chrome slag of the stainless steel making furnace.

Meanwhile, Table 4 shows the Cr and Fe recovery rates according to the FeO use ratio of the present invention.

FeO usage wt%) 2.5 10 20 30 40 50 Cr recovery (%) 45 88 89 90 91 91 Fe recovery (%) 80 96 97 97 97 97 Cr component (wt%) 26 33 29 25 23 21 Fe component (wt%) 53 52 58 62 65 68

* In Table 4, the Cr recovery (%) is [T.Cr content of product / T. Cr content in crude chrome slag before SAF operation] and Fe recovery rate (%) [Product T.Fe content / T.Fe content in the slag], and Cr and Fe components (wt%) indicate the Cr and Fe contents of the products in the slag after the SAF operation.

As shown in Table 4, when the FeO was added in the range of 2.5 to 50 wt% to the ham chromium converter slag in the SAF operation, the Cr and Fe recovery rates were excellent.

While the present invention has been particularly shown and described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of course, this is possible. Accordingly, the scope of the present invention should not be limited to the described embodiments, but should be defined by the following claims as well as equivalents thereof

Claims (4)

A method for recovering valuable metals from chrome slag made of stainless steel, which comprises CaO, SiO ₂ , Al ₂ O ₃ , MgO and Cr ₂ O ₃ using a melt reduction furnace (SAF)
When operating a melting reduction electric furnace (SAF)
Adding FeO, which satisfies the following relational expression 1-2, to the above-mentioned ham chromium slag in the range of 2.5 to 50 wt% per 1 ton of the chromium slag;
Reducing the chromium slag using the amount of carbon in the range satisfying the following formula 3; And
A method for recovering valuable metals from chrome slag of a stainless steel making machine, characterized in that the basicity [CaO + MgO) / SiO ₂ ] of the resulting slag is controlled in the range of 0.7 to 1.5 after the melting and reduction of the chromium slag.
[Relation 1]
_{FeO = (MgO + Cr 2 O} 3) × 0.15
[Relation 2]
2.5? (MgO + Cr ₂ O ₃ ) x 0.15? 50
[Relation 3]

Where α and β are the proportions of Fe and chromium in the metallic state, respectively, incorporated in the chromium slag, and α and β are in the range of 0.5 to 1.0, respectively. Input T.Fe, Input T.Cr and Input T.Si refer to the total amount of each component per ton of raw slag.
The steel slab of claim 1, wherein the steelmaking furnace chrome slag contains 5 to 25% of CaO, 15 to 35% of SiO ₂ , 0 to 20% of Al ₂ O ₃ , 5 to 40% of MgO, And Cr ₂ O ₃ : 4 to 40%. A method for recovering valuable metals from chrome slag.
The method of claim 1, wherein the coke is used as the carbon source, and at least one of aluminum, silicon, and silicon carbide (SiC) is used as a reducing agent in addition to the coke to reduce the chromium slag. A method for recovering valuable metals from steelmaking furnace chrome slag.
The method as claimed in claim 1, wherein the operation is performed such that the completion of the melting and reduction of the chromium-containing slag is carried out at a time point of 30 to 50% of the capacity of the SAF transformer, How to recover.

Images