KR101089375B1 - Method and apparatus for preventing dust accretion during bath smelting process - Google Patents

Abstract

The present invention provides a method and apparatus for the purpose of preventing dust accumulated and fixed in the waste heat boiler in the non-ferrous metal smelting by the bath smelting method, the method of the present invention is the oxidation by oxygen enriched air supplied through the lance As the concentration of the desired nonferrous metal increases, the non-ferrous metal by the bath smelting method comprising a smelting furnace in which slag is generated by impurities and a waste heat boiler in which shear is communicated with an uptake flow path formed behind the lance of the smelting furnace. A smelting apparatus comprising the steps of: supplying an oxygen-containing gas in front of the waste heat boiler behind the lance of the smelting furnace and mixing it with the smelting gas.

Bath Smelting, Non-Smelting

Description

Method and apparatus for preventing dust accumulation in bath smelting method {Method and apparatus for preventing dust accretion during bath smelting process}

The present invention relates to a method and apparatus for preventing the dust contained in the smelting gas generated in the bath smelting method of non-ferrous metals such as copper, nickel, zinc, and lead to accumulate and adhere to the surface of a waste heat boiler.

Applicant smelts copper and manufactures sulfuric acid from the by-product of copper smelting. Applicant's smelting plant 2 has been operating since 1998 by adopting the Mitsubishi process, a type of bath smelting process. The bath smelting method is generally a method of top blowing through a lance installed at the upper side of a smelting furnace during smelting of nonferrous metal so that the oxidation reaction of ore occurs in the molten metal at the bottom of the smelting furnace.

The Mitsubishi process, a type of bath smelting process, is a copper smelting process developed and commercialized by Mitsubishi Materials of Japan, and it can be produced continuously by treating copper concentrate to produce blister copper. It is differentiated from copper smelting method and is recognized for its advantages in terms of productivity, energy efficiency and space utilization. In addition, each of the smelting furnaces constituting the method is connected to the covered tangs, and the molten metal moves through these tangs so that less smelting gas or dust is scattered, which is a great method in terms of environment.

The main equipment implementing the Mitsubishi continuous smelting method in the applicant's smelting plant 2 consists of smelting furnace, separation furnace, conversion furnace, refinery furnace, and each furnace is connected to the water furnace, so that the molten metal is molten. It is configured to continuously flow and continuously react by gravity from the furnace to the refinery.

Melting Furnace is a furnace that concentrates Cu ~ 40 ~ 40% copper concentrate with oxygen to concentrate the Cu 68% Matt. When copper concentrate is continuously introduced into the furnace through the lance installed through the upper side of the furnace with oxygen-enriched air and flux, iron and sulfur in the copper concentrate react with oxygen and are removed to concentrate copper. At this time, the heat generated by the oxidation of the copper, and a copper slag (Slag) is the main component of the copper oxide is removed is produced in the molten state. The resulting mat and slag enter the separation furnace continuously through the runway.

Separation furnace is a furnace for separating the slag and mat produced in the smelting furnace. The mat and the slag are separated by the difference in specific gravity, and the mat is charged to the conversion furnace continuously through siphon and runway. Slag is continuously tapped and water granulated.

The converter is a furnace that makes Cu 99% copper by reacting 68% of the Cu separated from the separator with oxygen. The mat inside the converter is continuously converted to metallic copper (Blister Copper) by reacting with oxygen-enriched air and flux supplied through a lance installed through the converter. The produced copper (Blister Copper) is continuously charged into the refinery furnace, which is the next process, through siphon and tapping. The slag produced in the converter is also continuously crushed and reloaded into the furnace and the separation furnace.

Blister copper produced in the conversion furnace is cast in the form of a copper anode (Copper Anode, Cu 99.5%) to remove the residual sulfur and oxygen from the refinery and then electrolyze.

The smelting by the bath smelting method inevitably involves the generation of dust. The dust is mixed with a high-temperature smelting gas containing sulfur dioxide, which is generated during the oxidation of copper concentrate and passes through the waste heat boiler. The smelting gas passes through the radiant and convective zones of the waste heat boiler and is cooled by transferring waste heat. In this process, the dust is mixed with the smelting gas and settles under the waste heat boiler by gravity, and the remaining dust passes through the electrostatic precipitator. The filtered and dust filtered smelting gas is fed to the sulfuric acid plant and used for the production of sulfuric acid.

The main constituents of the dust are sulfides such as copper sulfide (Cu ₂ S) and iron sulfide (FeS). Some of these dusts settle to the bottom of the waste heat boiler and are not easily cleaned and accumulated and stuck to dust accumulation. Forming water deteriorates the efficiency of the waste heat boiler and hinders the flow of smelting gas, and in serious cases, there is a problem that causes the waste heat boiler to leak.

In addition, when the dust is not sedimented smoothly in the waste heat boiler can not be removed, the remaining amount until the electrostatic precipitator, there was also a problem that the quality or yield of sulfuric acid produced in the subsequent sulfuric acid manufacturing process is reduced.

This was not limited to copper smelting by the applicant's bath smelting method, but was a common problem with the bath smelting method of general nonferrous metals with dust generation and equipped with a waste heat boiler.

Accordingly, an object of the present invention created by recognizing the above problems is to prevent dust accumulation in the bath smelting method, which can prevent the dust generated in the bath smelting method of the nonferrous metal from being accumulated and fixed in the waste heat boiler. It is an object of the present invention to provide a method and apparatus.

In addition, the present invention is to provide a method and apparatus for preventing dust accumulation in a bath smelting method, which can prevent dust accumulation and improve the quality and productivity of sulfuric acid produced in a subsequent sulfuric acid production process.

In order to achieve the object of the present invention as described above, as the oxidation of the oxygen enriched air supplied through the lance proceeds to increase the concentration of the target non-ferrous metal while producing slag by impurities, In the non-ferrous metal smelting apparatus according to the bath smelting method having a waste heat boiler in which shear is communicated to the uptake flow path formed in the rear of the lance,

It provides a dust accumulation prevention method in the bath smelting method comprising the step of supplying oxygen-containing gas in front of the waste heat boiler behind the lance of the smelting furnace and mixing with the smelting gas.

In addition, the oxygen-containing gas provides a dust accumulation prevention method in the bath smelting method, characterized in that supplied from the rear of the lance of the smelting furnace, the front of the uptake flow path.

In addition, the oxygen content of the oxygen-containing gas provides a dust accumulation prevention method in the bath smelting method characterized in that more than the sum of the oxide reaction to the dust mixed in the smelting gas and the theoretical amount of oxygen required for the sulfate reaction of the oxide. .

In addition, the present invention provides a method for preventing dust accumulation in a bath smelting method further comprising the step of supplying an oxygen-containing gas from the front end of the waste heat boiler and mixing with the smelting gas.

In addition, the oxygen content of the oxygen-containing gas supplied from the front of the waste heat boiler is more than the theoretical oxygen amount required for the oxide reaction for the dust mixed in the smelting gas passing through the uptake flow path, the oxygen-containing gas supplied from the inner shear of the waste heat boiler The amount of oxygen in the present invention provides a method for preventing dust accumulation in the bath smelting method, characterized in that more than the theoretical amount of oxygen required for the sulfate reaction of the oxide formed in the uptake passage.

In addition, in order to achieve the object of the present invention as described above, as the oxidation of the oxygen enriched air supplied through the lance progresses the concentration of the target nonferrous metal while the slag is generated by the impurities and the smelting, In the non-ferrous metal smelting apparatus according to the bath smelting method having a waste heat boiler in which shear is communicated to the uptake flow path formed behind the lance of the furnace,

Provided is a dust accumulation preventing device in the bath smelting method, characterized in that at least one nozzle for supplying an oxygen-containing gas in front of the waste heat boiler behind the lance of the smelting furnace.

In addition, the nozzle provides a dust accumulation preventing device in the bath smelting method characterized in that the nozzle is installed in front of the uptake flow path behind the lance of the smelting furnace.

In addition, the nozzles are provided with a dust accumulation prevention device in the bath smelting method characterized in that arranged side by side or more in a row so as to be the full width or more than the inlet width of the uptake flow path.

In addition, there is provided a dust accumulation prevention in the bath smelting method characterized in that at least one nozzle for supplying the oxygen-containing gas to the front end of the waste heat boiler to be mixed with the smelting gas is additionally installed.

In addition, the nozzle is a dust accumulation prevention device in the bath smelting method characterized in that the air curtain by the oxygen-containing gas injected through the nozzle is composed of the number and diameter so as not to touch the molten surface of the bottom of the smelting furnace to provide.

In addition, the nozzle is composed of a number and aperture so that the air curtain by the oxygen-containing gas injected through the nozzle is formed directly up to the molten surface of the bottom of the smelting furnace, dust accumulation prevention in the bath smelting method Provide a device.

In addition, the nozzle provides a dust accumulation preventing device in the bath smelting method, characterized in that formed to have a selected angle in the range from vertical to 45 degrees with respect to the smelting gas flow.

The method and apparatus of the present invention, by preventing the accumulation and fixation of dust in the waste heat boiler by solving the problems such as deterioration of the efficiency of the waste heat boiler due to the dust accumulation, obstruction of smelting gas flow, leakage of waste heat boiler, etc. by the bath smelting method It is effective to smoothly smelt nonferrous metals.

In addition, since dust can be smoothly settled and removed in the waste heat boiler, the quality and yield of sulfuric acid produced in a subsequent sulfuric acid manufacturing process are improved.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 schematically shows the configuration of the smelting furnace to which the present invention is applied and the waste heat boiler connected thereto.

Here, the smelting furnace may be a smelting furnace for concentrating copper concentrate to a mat, for example, copper smelting, or a conversion furnace for increasing the copper concentration of the mat to produce a highly concentrated mat. The same applies to the smelting of other nonferrous metals. Hereinafter, for convenience of description, a melting furnace for concentrating copper concentrate into a mat will be described as an example.

A lance 11 is penetrated through the ceiling of the molten metal furnace 10. When copper concentrate is continuously introduced into the smelting furnace 10 together with the oxygen-enriched air and the material through the lance 11, iron and sulfur in the copper concentrate react with oxygen to be removed, and copper is concentrated to produce a mat. Slag, the main component of the removed iron oxide, is produced in the molten state. In addition, in this process, smelting gas including dust is generated, and smelting gas including dust is supplied through the uptake passage 12 in front of the waste heat boiler 20 to be supplied into the waste heat boiler 20.

In the waste heat boiler 20, dust contained in the smelting gas is settled and sinks into the waste heat boiler, while some are accumulated and fixed on the wall of the waste heat boiler 20 to form a dust aggregate. As a result of the operation of the smelting system, these dust deposits were mainly caused at the front end of the waste heat boiler indicated by 'a', causing great damage.

On the other hand, the inventors investigated the components of the dust accumulation accumulated and fixed inside the waste heat boiler 20, most of the components were sulfides (Sulfide). In view of this relationship between the sulfide and the dust accumulation, it was considered that the high viscosity and sticky nature of the sulfide was a cause of easy accumulation and fixation on the wall of the uptake passage 12 or the waste heat boiler 20. On the other hand, unlike the sulfide, sulfate (Sulfate) has been found to maintain the soft state inside the waste heat boiler 20, even if attached to the wall has a property that easily falls by gravity.

Accordingly, the study has been conducted on a method and apparatus for making the sulfide smoothly converted to sulfate by taking appropriate measures in consideration of the internal temperature conditions of the molten furnace 10 and the waste heat boiler 20.

As a result of the measurement, the temperature around the lance 11 was 1,300 degreeC, the temperature in the uptake flow path 12 was 1,250 degreeC, and the temperature of the front end of waste heat boiler 20 (near b point) was about 600-700 degreeC.

Figure 2a, b shows the balance composition of the dust according to the oxygen concentration of the smelting gas, Figure 2a shows the balance composition at 1,200 ℃ of the smelting gas (Off-Gas) containing 40% by weight of sulfur dioxide (SO ₂ ), Figure 2b shows the equilibrium composition at 600 ℃.

As shown, as the oxygen concentration in the smelting gas increases, oxides form a stable phase at a wide range at 1,200 ° C, and sulfates form a stable phase at a wide range at 600 ° C. These results apply almost the same to the region near the temperature even if not necessarily 1,200 ° C and 600 ° C.

In view of this, the present inventors first convert the sulfide to sulphate, and in the equilibrium and kinematic view, the process of converting the sulfide to the oxide in the high temperature region first, followed by the conversion of the oxide to the sulfate in the low temperature region By going through the process, the present invention has been completed so that problems due to the presence of sulfides do not occur over the entire area, while conversion of sulfides to sulfates occurs more completely and easily.

Taking copper smelting carried out by the applicant as an example, the high temperature region, the low temperature region and the entire reaction in the present invention are represented by the following chemical reaction formulas, respectively.

[Sulfide → Oxide]

Cu ₂ S + 1.5 O ₂ → Cu ₂ O + SO ₂

FeS + 1.5O ₂ → FeO + SO ₂

[Oxide → Sulfate]

Cu ₂ O + 2SO ₂ + 1.5 O ₂ → 2CuSO ₄

2FeO + 3SO ₂ + 2O ₂ → Fe ₂ (SO ₄ ) ₃

[Overall reaction]

Cu ₂ S + SO ₂ + ₃ O ₂ → 2CuSO ₄

2FeS + 5O ₂ + SO ₂ → Fe ₂ (SO ₄ ) ₃

Formula 1 is a reaction that changes from sulfide to oxide, which occurs stably at a relatively high temperature as shown in FIG. 2a, and Formula 2 is a reaction that occurs stably at a relatively low temperature, as shown in FIG. to be. As shown in Equation 3 showing the total reaction of the above two reactions, the reaction of sulfide to sulfate is completed by the total reaction of the reaction at high temperature and the reaction at low temperature.

Ore throughput and dust incidence vary between operating conditions and smelters, but in general, the amount of oxygen to be added can be calculated by considering the composition of the dust in the amount of dust generated (= concentrate supply * dust generation rate).

For example, in the applicant's smelting plant 2,

Continuous supply of copper concentrate: 120 t / h

Dust generation rate: 2% (ie 2% of the continuous supply of copper concentrate is generated as dust)

Dust composition: Cu ₂ S + FeS

In this condition, the amount of oxygen required for the reaction of Chemical Formula 1 is 4.7 Nm ³ /conc.t (conc.t means 1 ton fed continuously), which is necessary for the reaction of Chemical Formula 2 The amount of oxygen is 4.4 Nm ³ /conc.t and the amount of oxygen required for the entire reaction is 9.1 Nm ³ /conc.t. In terms of air volume, it is 22.4 Nm ³ /conc.t, 21.0 Nm ³ /conc.t, and 43.4 Nm ³ /conc.t, respectively. When using oxygen enriched air, the amount of oxygen enriched air varies depending on the oxygen enrichment degree. .

According to the calculation result, first, 100% of the total theoretical oxygen amount (9.1 Nm ³ /conc.t) is required to change the amount of theoretical oxygen (4.7 Nm ³ /conc.t) in order to change the sulfide into the oxide in the high temperature region near the uptake flow path. ), And experiments (Example 1) of dividing the theoretical oxygen amount (4.4 Nm ³ /conc.t) required for the conversion of oxides to sulfates in the low temperature region of the waste heat boiler were performed. An experiment (Example 2) in which all of 14 Nm ³ /conc.t, which is 150% of 9.1 Nm ³ /conc.t), was supplied in a high temperature range was performed.

The supply in the high temperature region was performed by one or more nozzles 13 installed in the rear of the lance 11 of the smelting furnace 10 and in front of the uptake flow passage 12, as shown in FIG. Was supplied through the nozzle 21 provided on the front end side of the waste heat boiler 20.

The nozzle 13 for supplying the oxygen-containing gas in the high temperature region may be formed perpendicular to the ceiling of the smelting furnace 10 as shown in the drawing, or alternatively, the smelting gas distributed from the ceiling of the smelting furnace 10 to the molten surface. It is also preferable to install inclined so that mixing is performed over a large area, that is, the area of the air curtain formed by the nozzle 13 is large.

On the other hand, the nozzle 13 in the high temperature region is arranged to have a total width or more than the inlet width of the uptake flow passage 12 as shown in FIG. It is arranged side by side more. This is to supply oxygen evenly to the smelting gas flowing into the uptake passage 12.

The flow rate of the oxygen-containing gas injected through the nozzle 13 is not good, but should be limited. First, a kind of air curtain formed by the oxygen-containing gas injected by the nozzle 13 should not touch the molten surface of the bottom of the smelting furnace 10. This is because excessive oxygen supply in the bath smelting method, such as when oxidation occurs by reaction with a substance in the molten metal, does not maintain a desired non-ferrous metal concentration in the smelting furnace 10, results in undesirable results. Therefore, the nozzle 13 should be configured with a number and diameter so that the air curtain by the oxygen-containing gas injected through the nozzle 13 does not touch the molten surface of the bottom of the smelting furnace 10.

In addition, the nozzle 13 is preferably composed of a number and aperture so that the air curtain by the oxygen-containing gas injected through the nozzle 13 is formed directly above the molten surface of the bottom of the smelting furnace 10. . This is because the smelting gas and oxygen flowing into the uptake flow passage 12 are smoothly mixed as long as the air curtain is lowered to the extent that it does not touch the molten surface.

As described above, the nozzle 13 may be installed to be inclined to increase the mixing area. However, when the nozzle 13 is installed to be excessively inclined, the total length of the air curtain should be increased, and for this purpose, the flow rate should be increased. As described above, excessive gas inflow is not desirable due to the nature of the bath smelting method. As a result, it was found that it may be inclined up to about 45 degrees from the vertical with respect to the smelting gas.

In FIGS. 1 and 3, the nozzle is installed on the ceiling of the smelting furnace 10 and in front of the uptake flow path 12 behind the lance 11, but is not limited thereto, and the rear waste heat boiler 20 is not limited thereto. Since it is good if it is a high temperature area | region of the front, it may be provided, for example in the beginning of an uptake flow path 12, or about intermediate.

In the input amount indicated by the red dotted line with respect to the theoretical amount 9.1 Nm ³ /conc.t indicated by the blue dotted line in FIG. Oxygen-containing gas was introduced at the first position (position of the nozzle 13), which is a high temperature region, and the second position (position of the nozzle 21), which is a low temperature region in front of the waste heat boiler 20.

1. Changes in oxygen concentration in the uptake flow path

In the uptake flow passage 12, shown in FIG. 1, under the oxygen injection conditions of Example 1, in which the amount of oxygen of 4.7 Nm ³ /conc.t in the first position and 4.4 Nm ³ /conc.t in the second position is introduced. Oxygen concentration was measured at point a, and the result is shown in FIG. 3.

As can be seen in Figure 4, if the supply of theoretical oxygen for the conversion of sulfide to oxide, if the reaction does not occur, the oxygen concentration of 2.5% increased from 0.6% to 1.9% before the input, but the actual measurement results The concentration is 1.0%. It can be seen from this that oxygen is consumed and the reaction of Formula 1 occurs.

Here, the theoretical concentration at the reaction efficiency of 100% is 1.2%, while the measured concentration is 1.0% and 0.2% more oxygen is consumed.There is some unreacted ore in the dust, which increases the oxygen consumption, It is possible to estimate that the dust incidence is slightly higher than the 2% that was originally identified.

2. Changes in the sulfate ratio of dust

Sulfide, oxide and sulfate ratio analysis and phase analysis by collecting dust from point b at the front end of the waste heat boiler 20, point c at the end of the radiant area of the waste heat boiler 20, and point d at the end of the radiant area of the waste heat boiler 20. Was carried out. The particle size of particles at b, c, and d in the waste heat boiler radiant area decreased in the order of b, c, d, and accordingly, the residence time of the dust was short in the order of d, c, b.

In the past, the accumulation and fixation of dust occurred mainly at the front end of the waste heat boiler 20, and the change in the composition of dust at point b according to the oxygen supply is illustrated in FIG.

As shown in Fig. 5, when the ratio of sulfides remaining in the first 20% range is to inject oxygen close to the theoretical amount of oxygen (Example 1), the amount of oxygen close to 150% of the theoretical amount of oxygen is added as in 50% (Example 2) can be seen to increase by 90%.

As a result of the experiment, rather than dividing the amount of oxygen introduced into the first position and the second position into the respective theoretical oxygen amounts, it is not necessary to put the oxygen in the second position and to inject excess oxygen amount more than the total theoretical oxygen amount. It can be seen that this results in better results in increasing the percentage of sulfate in the waste heat boiler. In other words, even if the entire amount of oxygen supply is supplied from the first position, it is used for the oxide reaction at high temperature and the remaining oxygen is used for the sulfate reaction by moving to the waste heat boiler in a state mixed with the smelting gas. There seems to be no.

Although a significant portion of the specific details for carrying out the invention have been described in connection with the copper smelting that the applicant is running, this is only for the sake of understanding, and those skilled in the art of non-ferrous smelting have a smelting furnace having a lance and a It will be readily understood that the present invention can be applied to a non-ferrous smelting method and apparatus by a general bath smelting method having a rear waste heat boiler.

Figure 1 schematically shows the configuration of the smelting furnace to which the present invention is applied and the waste heat boiler connected thereto.

2a and 2b show the equilibrium composition of dust according to the oxygen concentration of the smelting gas.

Figure 3 schematically shows the configuration seen from the top of the smelting furnace.

4 is a graph showing the amount of oxygen-containing gas in accordance with an embodiment of the present invention.

5 is a graph showing a change in the composition of the dust according to an embodiment of the present invention.

Claims (12)

As the oxidation of the oxygen enriched air supplied through the lance progresses, the concentration of the desired nonferrous metal increases, while the shear is in communication with the uptake flow path formed behind the lance of the smelting furnace and the slag generated by the impurities. In the non-ferrous metal smelting apparatus by the bath smelting method having a waste heat boiler, The method of preventing dust accumulation in a bath smelting method comprising the step of supplying an oxygen-containing gas in front of the waste heat boiler behind the lance of the smelting furnace and mixing with the smelting gas. The method of claim 1, And the oxygen-containing gas is supplied from the rear of the lance of the smelting furnace and from the front of the uptake flow path. The method according to claim 1 or 2, The oxygen content of the oxygen-containing gas is a dust accumulation prevention method in the bath smelting method, characterized in that more than the sum of the oxide reaction to the dust mixed in the smelting gas and the theoretical amount of oxygen required for the sulfate reaction of the oxide. The method of claim 1, And supplying an oxygen-containing gas from the front end of the waste heat boiler and mixing the smelting gas. The method of claim 4, wherein The oxygen content of the oxygen-containing gas supplied from the front of the waste heat boiler is equal to or more than the theoretical oxygen amount required for the oxide reaction with respect to the dust mixed in the smelting gas passing through the uptake flow passage, and the oxygen content of the oxygen-containing gas supplied from the inside shear of the waste heat boiler. A method for preventing dust accumulation in a bath smelting method, characterized in that it is more than the theoretical amount of oxygen required for the sulfate reaction of the oxide formed in the silver uptake flow path. As the oxidation of the oxygen enriched air supplied through the lance progresses, the concentration of the desired nonferrous metal increases, while the shear is in communication with the uptake flow path formed behind the lance of the smelting furnace and the slag generated by the impurities. In the non-ferrous metal smelting apparatus by the bath smelting method having a waste heat boiler, And at least one nozzle for supplying an oxygen-containing gas in front of the waste heat boiler behind the lance of the smelting furnace. The method of claim 6, And said nozzle is installed in front of said uptake flow path behind said lance of said smelting furnace. The method of claim 6, And the nozzles are arranged side by side or more in parallel so as to have a total width equal to or greater than an inlet width of the uptake flow path. The method of claim 6, At least one nozzle for supplying an oxygen-containing gas to the front end of the waste heat boiler and mixing with the smelting gas is additionally installed in the bath smelting method. The method of claim 6, The nozzle is dust accumulation prevention device in the bath smelting method characterized in that the air curtain by the oxygen-containing gas injected through the nozzle is formed of a number and aperture so as not to touch the molten surface of the bottom of the smelting furnace. The method of claim 6, The nozzle is dust accumulation prevention device in the bath smelting method characterized in that the air curtain by the oxygen-containing gas injected through the nozzle is formed of a number and aperture so as to be formed directly above the molten surface of the bottom of the smelting furnace. The method of claim 6, And the nozzle is formed to have a selected angle in a range from vertical to 45 degrees with respect to the smelting gas flow.

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