JPH101728A - Reduction treatment of tin oxide and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to efficiency and cost effectively execute the reduction treatment of tin oxide while preventing the evaporation loss of tin as far as possible. SOLUTION: The inside of a furnace body 2 is segmented by a partition wall 6 which is a refractory wall to a reduction treating chamber 7 and a heating chamber 8. The mixture 16 composed of the tin oxide and carbonaceous reducing agent supplied into the reduction treating chamber 7 is indirectly heated via the partition wall 6 by the high-temp. gas introduced into the heating chamber 8. As a result, the tin oxide is subjected to the reduction treatment and the molten metal thereof is taken outside the furnace body 2 from a tap hole 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tin oxide reduction treatment method for purifying or regenerating metallic tin from a raw material containing tin oxide, and a tin oxide reduction treatment apparatus for performing the method.

[0002]

2. Description of the Related Art The most common technique for purifying metallic tin from a raw material containing tin oxide (a mixture of tin oxide and tin oxide SnO ₂ as a main component) is a tin stone or the like. This is a reduction treatment of tin oxide in a tin raw material ore, and is performed by a process as shown in FIG. First, a tin oxide raw ore from which impurities such as S, Sb, As, W, Cu, and Pb have been removed by preliminary treatment is smelted using an electric furnace or a reflection furnace. That is, 10 to 15% by weight of coal,
A carbonaceous reducing agent such as charcoal or coke is mixed and heated in a furnace, and SnO ₂ is reduced by the following reaction.

[0003] SnO ₂ + 2C → Sn + 2CO (1) SnO ₂ + 2CO → Sn + 2CO ₂ (2) The reaction gradually starts at about 600 ° C., but is still inactive, and becomes suddenly active at 900 ° C. or higher. However, considering the temperature at which the fluidity of the slag can be obtained at 1200 ° C., the above reduction reaction is usually performed at around 1200 ° C. 1
When the temperature exceeds 200 ° C., the rate of evaporation of tin itself (vaporization loss) increases. This ore smelting produces crude tin (about 90% Sn) and slag (10-15% Sn). The crude tin is sent directly to the next purification step. Meanwhile, the slag is sent to the entanglement smelting process. Here, in order to collect Sn in the slag (also called entangling), it is strongly reduced in an electric furnace. Due to this strong reduction, an excess amount of iron (F
e) as a hard head (FeSn). Thereafter, silica sand is added and reduction smelting is performed at about 1500 ° C., and the remaining Fe is removed as an Fe—Si alloy. The crude tin (Sn 90%) thus obtained is sent to a purification step. In the refining step, impurities (most of Fe, C
u, As) is eluted. Alternatively, the impurities are oxidized and removed and separated as suspended solids containing Fe, Zn, Pb, As, and the like. Thereby, Sn content 99.8-99.
9% of metallic tin is obtained. If necessary, this metal tin is further sent to an electrolytic refining step, cast on an anode and electrolyzed to obtain Sn99.99% metal tin.

In the above-mentioned tin oxide reduction process, an electric furnace or a reverberatory furnace is widely used as a furnace for reduction. Tin ore and its refining process become electrically conductive at relatively low temperatures. For example, in the case of an electric furnace, when a tin oxide-containing ore is first charged into the furnace and three-phase alternating current is applied, the tin ore becomes a resistor and immediately generates heat and starts melting. If coal is added to the molten tin ore to cause a reduction reaction, metal tin can be easily obtained.
In the case of a reverberatory furnace, a mixture of a tin oxide-containing raw material and a reducing agent such as coke is charged into a refractory furnace. The mixture is heated and melted to reduce tin oxide by a direct fire method in which a fuel gas such as LPG is directly injected into a furnace by a burner and burned.

[0005] On the other hand, reduction treatment of tin oxide has been carried out for non-tin ore such as common tin stone. For example, Japanese Patent Publication No. 46528/1986 discloses that tin oxide is contained in plating sludge. A method of recovering metallic tin by reducing hydrogenated tin oxide with hydrogen is disclosed. This is a technique for recovering metallic tin by hydrogen-reducing plating sludge containing an organic substance generated in, for example, ferrostan type electric tin plating. First, the plating sludge is burned before hydrogen reduction to thermally decompose and remove the organic substance. . Next, the product from which the organic substances have been removed is placed in a mesh container and subjected to hydrogen reduction to recover high-grade metallic tin.

[0006]

However, when an electric furnace is used as a furnace for reducing tin oxide, the power supply is expensive. In addition, since the raw material is heated and melted by the plasma arc, a high temperature of several thousand degrees Celsius is actually generated in the vicinity of the starting point and the landing point of the microscopically small arc. This local high temperature has a problem in that tin evaporates and evaporates, resulting in a vaporization loss of 20 to 30%.

[0007] In order to reduce the loss of vaporization of tin, it is common practice to cover the mixture of the tin oxide raw material and coal with a slag layer and to operate in a so-called submerged manner. It is desirable that the slag has as low a melting point as possible. For example, FeO-CaO-Si having the lowest melting point
O ₂ slag has a melting point of 1100 ° C. However, the difficulty in refining tin is the separation of Fe.
Is separated and removed to reduce the purified tin oxide, the above F which may cause Fe to be redissolved in the reduced metal tin.
The use of e-containing slag is very disadvantageous. Therefore, as a low melting point slag containing no Fe, CaF or Na is used.
The use of fluoride slags such as F and KF may be considered, but these are economically disadvantageous because they may accelerate the wear of refractories in the furnace.

After all, CaO—SiO ₂ containing no FeO
In this case, the slag melting point is as high as 1475 ° C. Therefore, in order to ensure the fluidity of the slag, the heating temperature is increased more than necessary, and not only the amount of input power increases,
This leads to a vicious cycle in which the vaporization loss of tin increases.

[0009] When a direct-fired burner heating type reflection furnace is used as a furnace for reducing tin oxide, a large amount of CO ₂ gas is present in the combustion exhaust gas. The reduction equilibrium condition of CO ₂ (11.2%) and CO in a reducing atmosphere is CO / CO ₂ =
In order to satisfy 0.24 (1000 ° C.), the total amount of CO emissions inevitably increases. Therefore, carbon monoxide gas poisoning and explosion may occur, and there is a problem that exhaust gas treatment becomes difficult.

[0010] Further, since the reverberatory furnace is a shallow furnace having a large cross-sectional area in order to secure a heat transfer area, there is a problem that the surface area of the hot water becomes extremely large and the vaporization loss of tin increases. On the other hand, in the case of the hydrogen reduction method of tin oxide in plating sludge disclosed in Japanese Patent Publication No. 61-46528, there is a risk of explosion due to leakage of hydrogen gas as a reducing gas and difficulty in obtaining a large amount of hydrogen gas. There is such a problem.

Accordingly, the present invention has been made in view of such conventional problems, and does not contain Fe (high purity), has a small vaporization loss of tin (high yield), and Low cost of exhaust gas treatment, low furnace wear (low cost), low CO gas emission (safe), no slag, no need to separate auxiliary materials such as silica stone and lime (easy to handle) oxidation An object of the present invention is to provide a method and apparatus for reducing tin.

[0012]

Means for Solving the Problems The present inventors can efficiently and economically carry out a reduction treatment of tin oxide while minimizing the loss of tin vaporization from a raw material containing tin oxide. In order to develop a method and an apparatus for reducing tin oxide, as a result of intensive research while repeating various experiments, indirect heating of a raw material containing tin oxide together with a carbonaceous solid such as coke or under a reducing gas atmosphere. As a result, they have found that the intended purpose can be achieved, and have completed the present invention.

That is, according to the first aspect of the present invention, there is provided a method for reducing tin oxide according to the present invention, wherein a raw material containing tin oxide and a reducing agent are indirectly heated by a heating means in a reduction processing chamber having a fire-resistant wall. And reducing tin oxide to a metal.

According to a ninth aspect of the present invention, there is provided a method for reducing tin oxide according to the present invention, wherein a raw material containing tin oxide is heated to a high temperature in a reducing chamber having a refractory wall under a reducing gas atmosphere. The above-mentioned tin oxide is reduced by supplying the above-mentioned inert gas or indirectly heating the mixture using a high-temperature inert gas and another heating means.

In the tin oxide reduction treatment method of the present invention,
Using an inexpensive and easily available reducing agent, the tin oxide-containing raw material is reduced by an indirect heating method under a reducing atmosphere. Therefore, there is an advantage that the amount of CO emission due to exhaust gas is extremely small. On the other hand, when the raw material and the reducing agent are directly heated by a heating burner, for example, as in a direct fire burner heating method using LPG gas, as described above, the CO contained in the exhaust gas of the heating burner is used. _{Since 2} exists in the reduction chamber, the reduction equilibrium condition (Pco / Pco ₂ )
CO emissions will also increase.

For example, when tin oxide is reduced at a reaction temperature of 1100 ° C., the amount of CO emitted by indirect heating is very small, about 1/40 that of direct heating. Therefore, exhaust gas treatment is easy and inexpensive. In addition, the safety is high without risk of carbon monoxide gas poisoning or explosion.

Further, according to the indirect heating method of the present invention, unlike in the case of the arc heating method in which the raw material is directly energized, which is one type of electric heating, a local high temperature does not occur due to the generation of an arc. Therefore, when the reduction temperature of both the indirect heating method and the arc heating method is set to the same 1200 ° C., the vaporization loss of tin is significantly reduced in the indirect heating method. If there is no vaporization loss, it is not necessary to use a slag having a high melting temperature to prevent this, so that the reduction reaction can be performed at a lower temperature, and the vaporization loss is further reduced.

In addition, since the heating and the reduction reaction are completely separated by using the indirect heating method, the heating can be controlled irrespective of the atmosphere of the reduction reaction. Therefore, there is an advantage that the air-fuel ratio of the heating burner can be freely set. Further, since the reduction reaction proceeds in a substantially closed reduction chamber, it does not come into contact with oxygen in the air. For this reason, there is also an advantage that if the temperature is raised to a temperature at which the reducing agent and the raw material containing tin oxide as a main component react, the reducing atmosphere is automatically established.

Hereinafter, the reduction treatment of tin oxide according to the present invention will be described in detail. First, the concept of the indirect heating method in the present invention will be described with reference to the drawings. The indirect heating method referred to in the present invention refers to a heating method in which a heating source used for performing a reduction reaction at a high temperature does not have any influence on a reducing atmosphere, and is isolated from oxygen in the atmosphere. It is performed in a state where it is held.

Typical examples of the indirect heating method include an electric heating method and a high-temperature gas heating method.
Electric heating methods include resistance heating, induction heating, infrared heating,
Electron beam heating and the like are included. However, the arc heating of the type in which electric current is directly applied to the raw material, which is one form of the electric heating method, is not included in the electric heating method of the present invention because the local high temperature of the generated arc causes loss of tin vaporization. .
In the following description, the heat sources used in these electric heating systems may be collectively referred to as electric heaters. In addition, a direct-fired system such as a general reverberatory furnace, which is one form of a high-temperature gas heating system, uses CO ₂ ,
Since the reducing atmosphere (CO / CO ₂ ) is affected by H ₂ O, it is not included in the indirect heating method of the present invention. Also, in the blast furnace, the coke is burned with air and heated to reduce the coke, thereby affecting the reducing atmosphere. Therefore, it is not included in the indirect heating method of the present invention.

When the indirect heating in the present invention is carried out by using a heating burner which is a high-temperature gas heating method, as shown in FIG. 1, a raw material tin oxide and a reducing agent (for example, solid (A carbonaceous reducing agent) and heated by a heating burner (gas burner, petroleum burner, pulverized coal burner, etc.) not shown. At that time, the reaction chamber A is isolated by a partition wall C made of a refractory or the like so that a burner exhaust gas component and oxygen in the atmosphere do not affect the atmosphere in the reaction chamber A,
Heat is applied through the partition wall C. At this time, the gas D generated by the reduction reaction is discharged out of the system. When combustion components such as CO and H ₂ remain in the generated gas D, they are burned in a combustor E outside the system and then released into the atmosphere. In practice, the reaction chamber A is provided with a charging port for charging the raw material tin oxide and the reducing agent, and a tap hole for discharging metal tin Sn obtained by reduction. Both the charging port and the tap are of a structure that can be hermetically closed.

In the case where the indirect heating in the present invention is carried out by using an electric heater which is an electric heating system, as shown in FIG. 2, the reaction chamber A in which the raw material tin oxide and the reducing agent are charged is sealed. And an electric heater F ₁ disposed on the outer side of the partition C.
To heat through the partition C. Alternatively, the reaction chamber A, is heated through the partition wall C by an electric heater F ₂ which is arranged inside the partition wall C.

As the electric heater F ₃ , for example, a sheathed wire heater insulated and sealed with a heating wire is used, and the sealed electric heater is disposed on the inner side of the partition wall C to form a reaction chamber A 3.
The case where the raw material is heated inside is also included in the indirect heating in the present invention. Also in this case, the raw material is indirectly heated by the heat generated from the heating wire and dissipated through the closed tube, so that the heating source does not directly affect the reducing atmosphere in the return reaction chamber A.

The above electric heaters F ₁ , F ₂ , F ₃
May be used in combination. When an induction heating method is used as the electric heating method, a graphite crucible or a silicon carbide crucible may be used as the reaction chamber A. The graphite crucible or silicon carbide crucible itself that has generated heat by induction heating becomes the heating source,
The raw material is heated indirectly without affecting the reducing atmosphere.

In the indirect heating method of the present invention, a reducing gas may be used as a reducing agent. As the reducing gas, a gas containing CO such as a blast furnace gas, a mixed gas, a generating furnace gas, or the like can be used. When using a reducing gas as a reducing agent, as shown in FIG. 3, a raw material tin oxide is charged into a closed reaction chamber A, and the reaction chamber A is partitioned by a heating burner or electric heating not shown. Indirect heating is performed via the wall C, and at the same time, the amount of reducing gas G required for reduction is introduced into the reaction chamber A to perform reduction. Reducing gas G
May be introduced by spraying or flowing on the upper surface of tin oxide, or a method of introducing from the bottom and side walls of the reaction chamber A and passing through the tin oxide particle layer.

When the indirect heating in the present invention is performed by using a heating burner B as shown in FIG.
Utilizing the heat of the exhaust gas discharged out of the furnace, it can be used for drying and preheating of the raw material tin oxide and / or reducing agent. As the equipment I for the drying or preheating, if a raw material charging equipment is used, heat loss and dust generation can be prevented. Alternatively, a dryer and a preheater can be separately installed and used. In any case, if the raw material or the reducing agent containing tin oxide is preheated and / or dried using the heat of the exhaust gas,
Next, the time required to raise the temperature of these materials to a predetermined temperature or evaporate moisture in the reduction treatment chamber is reduced, thereby reducing the reduction reaction time and improving the thermal efficiency of the reduction treatment. There is. In particular, when a graphite-based refractory or a silicon carbide-based refractory as described later is used as a material for the refractory partition of the reduction treatment chamber, these refractories are easily oxidized and damaged by water vapor. By drying the raw material containing tin oxide and the reducing agent in advance, there is an effect that damage to the refractory material can be prevented beforehand. Further, by preheating the raw material containing tin oxide and the reducing agent in advance, there is also an effect of reducing damage to the refractory material due to heat shock or thermal stress when the materials are charged into the reduction treatment chamber.

Further, the heat of the exhaust gas can be used in a metal tin melting facility J for holding the molten metal tin in a molten state or remelting the solidified metal tin. It is.

As the raw material containing tin oxide used in the present invention, a raw material free from impurities such as iron oxide is basically suitable. However, by performing a pretreatment for removing impurities such as iron oxide in advance, tin ores containing iron, such as natural sand tin and tin stone, can also be targeted. Further, tin scrap or the like generated in the tin plating step can also be used. In particular, in the case of tin and iron-containing sludge generated in a tin electroplating line, white sludge obtained by chemically treating the same is high-purity tin oxide containing tin oxide as a main component and removing iron as much as possible. is there. Therefore, if the white sludge is used as a raw material containing tin oxide (claim 10), the pretreatment and entanglement smelting process as in the case of tin ore is not necessary, and the tin oxide reduction treatment method of the present invention is directly performed. It can be suitably applied.

The reducing agent used in the present invention includes, for example, a solid carbonaceous reducing agent or a gas reducing agent (claims 2 and 5). In the former, coke, coal, charcoal and the like can be mentioned, and among them, coke is preferable. The form of the solid carbonaceous reducing agent is usually granular or powdery, and the reactivity differs depending on the particle size. Generally, the smaller the particle size, the better the reactivity. On the other hand, the larger the particle size, the better the separation between the metallic tin eluted from the tin oxide raw material and the solid carbonaceous reducing agent. In the present invention, it is desirable to use a reducing agent having an average particle size of 50 mm or less in consideration of the balance between reactivity and separability.

The solid carbonaceous reducing agent may be charged into the reduction chamber alternately with the raw material containing tin oxide in a layered manner (claim 3), or may be charged in a state where both are mixed in advance (claim 3). Item 4). When loading in layers, it may be a plurality of layers stacked horizontally in the vertical direction, or a plurality of layers stacked obliquely in the vertical direction, or as a layer arranged vertically in the left and right direction Is also good. In layered charging, the larger the number of divisions, the larger the contact area between the raw material and the reducing agent, and the faster the reduction reaction proceeds. In the case of the layered charging and the mixed charging, the reduction reaction proceeds faster because the mixed charging has a larger contact area. However, in the case of layered charging, there is no need for a mixer which is a mixing device for previously mixing the solid carbonaceous reducing agent and the raw material containing tin oxide, and there is an advantage that the equipment is simplified.

As the latter gas reducing agent, a gaseous carbonaceous reducing agent such as CO gas can be suitably used.
Among them, blast furnace gas, mixed gas, generator gas and the like containing carbon monoxide CO are easily available at steel works and can be used as a representative gas carbonaceous reducing agent. Generally the hydrogen gas H ₂ which is widely used as a gas reducing agent, the difficulty standpoint of mass obtained, in the present invention is excluded. By performing the heat treatment while blowing the gas reducing agent into the raw material containing tin oxide in the reduction processing chamber, the tin oxide in the processing chamber can be reduced under a favorable reducing atmosphere.

The ratio (mass ratio) of the amount of tin oxide in the raw material containing tin oxide of the present invention and carbon in the carbonaceous reducing agent charged into the reduction chamber is tin oxide: carbon = 100: 4. To 30 (mass ratio) (claim 7). Preferably it is 100: 8-23. When the mixing ratio of carbon is less than 4, the theoretical carbon amount required for reduction of tin oxide SnO ₂ is considerably lower, and as a result, the recovery of metallic tin Sn is greatly reduced.
On the other hand, if the mixing ratio of carbon exceeds 30, the amount of generated CO becomes very large, and it becomes difficult to treat the exhaust gas. In addition, the residue of the unreacted carbonaceous reducing agent (for example, coke) increases, and Subsequent processing becomes somewhat difficult, for example, separation becomes difficult.

The temperature of the reduction reaction of the tin oxide of the present invention is 600
To 1300 ° C. (claim 8). Preferably it is 900-1200 degreeC. When tin oxide is heated to 400 ° C. or higher in a reducing atmosphere, the tin oxide becomes unstable and reduction starts. However, when the temperature is lower than 600 ° C., the reaction speed is low and not practical. On the other hand, if the temperature exceeds 1300 ° C., the vaporization loss of Sn increases, the tin recovery rate sharply decreases, and the economic efficiency deteriorates. In particular, from the viewpoint of reducing the evaporation loss, it is preferable that the temperature does not exceed 1200 ° C.

According to a ninth aspect of the present invention, there is provided a method for reducing tin oxide according to the present invention. The tin oxide is reduced by heating with a gas. That is,
A raw material containing tin oxide and a reducing agent (for example, a solid carbonaceous reducing agent or a gaseous carbonaceous reducing agent) are charged into the reduction treatment chamber, and a gas such as nitrogen gas which has been heated to a high temperature by heat exchange or the like outside in advance The inert gas is heated while being fed into the reduction processing chamber. More specifically, when the reducing agent is a solid carbonaceous reducing agent, the reducing agent is charged into the reduction treatment chamber together with the tin oxide raw material, and the reduction treatment is performed while supplying a high-temperature inert gas into the reduction treatment chamber. The reducing treatment chamber is maintained in a reducing atmosphere by a reducing gas generated by thermal decomposition of the solid carbonaceous reducing agent.

On the other hand, if the reducing agent is a gaseous carbonaceous reducing agent, the tin oxide raw material is charged in the reduction treatment chamber in advance, and the high-temperature inert gas and the gaseous carbonaceous reduction agent are simultaneously or separately separated. While reducing. The reducing chamber is kept in a reducing atmosphere by a gaseous carbonaceous reducing agent mixed with an inert gas.

In any case, when the tin oxide raw material is heated by the above-mentioned high-temperature inert gas, the heating efficiency is higher than when the tin oxide raw material is heated through the refractory wall. Heating with a high-temperature inert gas and heating through a refractory wall can be used together, in which case there is an effect that the reduction treatment time is shortened.

According to a tenth aspect of the present invention, in the method for reducing tin oxide of the present invention, as a tin oxide raw material, a sludge mainly composed of tin oxide produced in an electroplating step is used. Since this sludge has an extremely low iron content, it can be used as a raw material containing tin oxide of the present invention without removing iron in advance, and tin resources can be easily recovered.

The apparatus for reducing tin oxide according to the present invention is a furnace used for reducing tin oxide. The furnace body is divided into a reduction chamber and a heating chamber by a refractory partition wall. The reduction processing chamber is provided with an exhaust port, a hot water outlet, a supply port for tin oxide and a carbonaceous reducing agent, and a heating means for indirectly heating the tin oxide and the carbonaceous reducing agent in the reduction processing chamber. Features (claim 11).

Preferably, the refractory partition wall is made of a basic refractory or a non-oxide refractory. In the former, S is a basic oxide for various basic refractories.
In consideration of the penetrating power of nO, a magnesium oxide MgO-based material having a moderate penetrating power is particularly preferable.
As the latter non-oxide type refractory, for example, a silicon nitride type refractory, a silicon carbide type refractory, a graphite type refractory or the like is preferable. When a carbon-based refractory such as silicon carbide or graphite-based refractory is used, the partition wall itself can be used as a heating source by heating the refractory with an induction heating method.

In the tin oxide reduction treatment apparatus according to the present invention, a plurality of reduction treatment chambers may be provided in the furnace body. When a plurality of reduction processing chambers are provided, the ratio of the area of the outer wall in contact with the outside air is reduced, and the thermal efficiency is improved. Furthermore, the time axes of the three steps of (A) raw material charging, (B) reduction, and (C) tapping, which are performed in each room, are slightly shifted, so that (A) raw material charging and (C) tapping Since the work steps can be arranged in order so that the work does not overlap, there is an advantage that continuous production without waste is enabled.

In the apparatus for reducing tin oxide according to the present invention, a heating burner can be used as means for heating the raw material containing tin oxide and the reducing agent. However, in this case, heating is performed from outside the refractory wall of the reduction treatment chamber and indirect heating is performed through the refractory wall, instead of directly heating the direct heat of the heating burner into the reduction treatment chamber and heating.

Further, an electric heater can be used as the heating means. In this case, the electric heater may be disposed on the outer surface side of the refractory wall of the reduction processing chamber, may be disposed inside the refractory wall of the reduction processing chamber, or may be disposed on the inner surface of the refractory wall of the reduction processing chamber. It may be arranged on the side. Alternatively, these arrangements may be used in combination.

In any case, since the indirect heating method using the heating means is employed, the atmosphere of the reduction processing chamber in which the reduction reaction is performed is not affected. For example, even in the case of a heating burner, the air-fuel ratio can be freely set regardless of the atmosphere of the reduction reaction, so that the heating can be easily controlled. Further, since the reduction reaction proceeds in the reduction chamber, contact with oxygen in the air can be easily prevented.

Further, in the apparatus for reducing tin oxide according to the present invention, a means for preheating and / or drying tin oxide and / or a reducing agent that exchanges heat with exhaust gas discharged from the heating chamber can be added. Item 14). This not only improves the thermal efficiency by effectively utilizing waste heat, but also removes the adverse effect of moisture on the furnace body material as described later.

In the reduction treatment of tin oxide of the present invention, an acid
As a raw material containing tin oxide, chemical
White sludge (high-purity tin oxide)
Wear. White sludge is tin tin made by the halogen method
Generated by plating line (hereinafter referred to as ETL)
It is obtained by chemically treating sludge. Its representative
An example of a typical composition is, for example, a dehydrated and dried solid
SnO in white sludge _TwoThe content is 78% and the Fe content is 0.1%.
4% or less.

The sludge generated by the halogen method ETL is N
a_TwoSnF₆, Na_ThreeFeF₆And the like as a main component. this
In a first reaction vessel with hot water and H_TwoO_TwoAnd add hydrothermal reaction
After that, the solution is filtered, and the solution is sent to the second reaction tank.
Mixed with NaOH _TwoSnF₆+ 4NaOH →
6NaF + SnO_Two↓ + H_TwoAcid precipitated by O reaction
Filtering tin oxide through a filter to obtain slurry-like white sludge
You. This is dewatered to dry white sludge.

According to the tin oxide reduction treatment method of the present invention,
From the tin oxide in the white sludge, it is possible to preferably recover the metallic tin. In addition, ferrostein method ETL
(Electric tin plating line) Even if the plating sludge is generated from a tin sludge mainly containing tin oxide as small as 5% or less, for example, the tin oxide in the plating sludge is reduced, It is possible to preferably recover the metal tin.

[0048]

Embodiments of the present invention will be described below with reference to the drawings. 5 and 6 show a tin oxide reduction treatment apparatus 1 according to the present invention, which includes a furnace main body 2, a raw material supply apparatus 3, and a heat source supply apparatus 4 as indirect heating means. In the following description, "front and rear" means left and right in FIG. 5, and "left and right" means left and right in FIG. 6, respectively.

The furnace body 2 has a box shape in which the bottom 5a of the furnace wall 5 is inclined downward toward the rear as shown in the figure. It is divided into a heating chamber 8. Each reduction processing chamber 7 and heating chamber 8
Each is surrounded by a furnace wall 5 and a partition wall 6 which are outer walls of the furnace main body 2. That is, each reduction processing chamber 7 includes front and rear walls 6 a and 6 b, a left and right side wall 6 which are a furnace wall ceiling 5 b and a partition wall 6.
c, 6c, and a bottom wall 6d, which is a rectangular box shape that is long before and after, and the bottom wall 6d is inclined downward and backward in parallel with the furnace wall bottom 5a. The heating chamber 8 includes a partition wall 6 around each reduction processing chamber 7 and a furnace wall 5 (excluding the furnace wall bottom 5a).
And between the opposing walls of the two reduction processing chambers 7, 7, and are entirely surrounded except for the upper surfaces of the two reduction processing chambers 7, 7. In addition, the distance between the partition wall 6 around each reduction processing chamber 7 and the furnace wall 5 (excluding the furnace wall bottom 5a) and the distance between the opposing walls of the two reduction processing chambers 7 and 7 are set to be substantially the same. The distance between the bottom wall 6d of each reduction processing chamber 7 and the furnace wall bottom 5a is set slightly larger.

Further, an exhaust port 9 and a supply port 10 are provided in the ceiling wall 5c of each reduction processing chamber 7, and a lower part of the rear wall 6b penetrates through the heating chamber 8 and the furnace wall rear part 5e to form a downward slope. A tap hole 11 extending inclining is provided. Supply port 10
Is openable and closable, so that the tap hole 11 is closed except when tapping. Note that the exhaust port 9 is connected to an exhaust system 9a provided with appropriate exhaust gas treatment means and the like.

Although the furnace wall 5 and the partition wall 6 are made of a refractory material having excellent heat resistance, the furnace wall 5 needs to have sufficient heat insulating properties as in the case of a furnace wall of a general heating furnace or the like. Therefore, it is made of a refractory material having excellent heat insulating properties in consideration of the wall thickness. On the other hand, as for the partition wall 6, since the inside of the reduction processing chamber 7 must be effectively heated by a heat source supplied to the heating chamber 8 as described later, the physical and thermal strengths must be sufficiently secured. The wall thickness is made as thin as possible, the heat conductivity is excellent, and tin oxide SnO ₂
Is a basic oxide produced during the reduction reaction of SnO
It is made of a basic refractory material (for example, a magnesium oxide refractory material or the like) which is hardly corroded by a metal or a carbon refractory material (for example, a graphite refractory material, a silicon carbide refractory material or the like) which is a non-oxide refractory material. Specifically, the inner surface of the partition wall 6 on the reduction processing chamber 7 side is lined with a magnesia-based basic refractory. However, as the magnesium oxide-based refractory material, magnesia alone is not good in spalling resistance, so magnesia chrome brick, magnesia carbon brick and the like are preferable.

The raw material supply device 3 includes a pair of left and right raw material hoppers 15 and 15 fixedly mounted on a frame 13 via a support base 14 at a position above the furnace body 2. Each raw material hopper 15 has a raw material / reducing agent mixture 1 in which tin oxide as a raw material and a carbonaceous reducing agent are mixed at a predetermined ratio.
6 are accommodated. In addition, a supply pipe 15a is provided below each raw material hopper 15, so that the raw material / reducing agent mixture 16 is uniformly distributed and supplied from the supply port 10 into each reduction processing chamber 7. .

The heat source supply device 4 is a heating burner,
As shown in FIG. 5, the heat source supply port 1 provided in the furnace wall bottom 5a
7, a combustor 18 installed outside the furnace body 2, and a heat source supply port 17, 17 from a combustion chamber 18a of the combustor 18.
And a combustion gas supply pipe 19 led to the combustion chamber 18.
As a heat source for indirectly heating the inside of the reduction processing chambers 7 and 7 through the partition wall 6, the combustion gas generated in a is supplied from the heat source supply ports 17 and 17 into the heating chamber 8. I have. The combustor 18 only needs to generate a combustion gas capable of heating the inside of the reduction processing chamber 7 to a temperature at which a reduction reaction (reaction between tin oxide and the carbonaceous reducing agent) occurs or higher (generally, 600 ° C. or higher). The combustion method is arbitrary. In this example, a burner combustion type using gas fuel is used as the combustor 18. In addition, exhaust ports 20 and 2 are provided above the furnace wall front part 5d and the furnace wall rear part 5e which are the front and rear walls of the heating chamber 8.
0 is provided. These exhaust ports 20,
Exhaust system 20 provided with exhaust gas utilization means such as equipment I for drying and preheating a raw material containing tin oxide or a reducing agent I or equipment J for dissolving metallic tin
a. The metal tin melting facility J is used to heat the collected metal tin to maintain it in a molten state, or to re-melt the once solidified metal tin as needed.

Next, an embodiment of the tin oxide reduction treatment method according to the present invention, which is carried out using the above-described reduction treatment apparatus 1, will be described. A raw material / reducing agent mixture 16 in which a raw material containing tin oxide and a reducing agent such as coke (solid carbonaceous reducing agent) are uniformly mixed at a predetermined ratio is stored in each raw material hopper 15. As a raw material containing tin oxide, tin oxide obtained by treating tin-plated sludge can be used in addition to the natural ore, sand tin and tin stone, which are obtained by removing impurities (particularly iron) in advance. (For example, Sn: 50
% Or more, and Fe: 5% or less).

Before supplying the raw material / reducing agent mixture 16,
First, the inner wall of the reduction processing chamber 7 is heated to about 1100 ° C. In this heating, the combustion gas generated in the combustion chamber 18a of the combustor 18 is introduced into the heating chamber 8 through the introduction pipe 19, and
By heating indirectly via When the inner wall temperature of the reduction processing chamber 7 reaches a predetermined value, the raw material / reducing agent mixture 16 in the raw material hopper 15 is supplied into each reduction processing chamber 7. The supply of the raw material / reducing agent mixture 16 is performed from the plurality of supply ports 10 in an equal distribution as described above. Therefore, the raw material / reducing agent mixture 16
Is supplied substantially uniformly.

After the supply ports 10 are closed, the temperature in the reduction chamber 7 is maintained at, for example, 1100 ° C. (steady operation). Usually, the temperature at which the tin oxide and the carbonaceous reducing agent undergo a reduction reaction is 400 ° C. or higher. Temperature of 400 ° C. or higher (for example, 6
(00 ° C.), the reduction treatment chamber 7 is generated by the reduction reaction represented by the above-described equations (1) and (2), in combination with the fact that the air (oxygen) does not enter the closed space. The reduction processing chamber 7 is maintained in a reducing atmosphere by carbon monoxide CO. Therefore, the reduction reaction is promoted in the reduction processing chamber 7 which is already preheated to 1100 ° C., and the tin oxide is reduced. To promote the above reduction reaction, the temperature of the reduction treatment chamber is in the range of 600 to 1300 ° C. However, from about 900 ° C., the solution loss reaction becomes active and the reaction becomes faster, while if it exceeds 1200 ° C., the vaporization loss of tin increases.
It is in the range of 00 to 1200 ° C. From the viewpoints of both the reaction rate and the loss of vaporization, more preferable are 1000 to 11
It is in the range of 50 ° C. Incidentally, to calculate the Sn-SnO ₂ reduction at the CO and CO ₂ equilibrium constant _{(Pco / Pco 2) sn-} sno 2 from the difference .DELTA.G ° Gibbs free energy by the following equation,
FIG. 7 is a plot of the relationship between the equilibrium constant (Pco / Pco ₂ ) and the temperature. (2ΔG ° co-co ₂ −ΔG ° sn-sno ₂ ) = − 19.14 × T ×
log (Pco ₂ / Pco) sn-sno ₂ ² where 2ΔG ° co-co ₂ = −564840 + 173.3 × T ΔG ° sn-sno ₂ = −584090 + 212.55 × T SnO ₂ is (Pco / Pco ₂ ) It can be seen that reduction can be achieved at 1000 ° C. with a low CO concentration of 0.24. That is, Sn
It can be said that the reduction of O ₂ can be performed in a relatively weak reducing atmosphere with a small (Pco / Pco ₂ ).

Thus, in the case of the present embodiment, by introducing the combustion gas into the heating chamber 8, the raw material / reducing agent mixture 16 in the reduction processing chamber 7 is indirectly heated via the partition wall 6. That is, unlike the prior art, the combustion gas from the combustor 18 is not directly introduced into the reduction processing chamber 7 and heated by direct fire. Therefore, the conditions of the reduction equilibrium are not affected by the properties of the combustion gas (particularly, the concentration of carbon dioxide). Therefore, carbon monoxide and carbon dioxide generated by the reduction reaction reach the reduction equilibrium quickly, and a good reducing atmosphere can be formed and maintained. Therefore, a reducing atmosphere required for the reducing reaction can be quickly formed, and the reducing process can be performed efficiently. In addition, the concentration of carbon monoxide in the exhaust gas discharged from the exhaust port 9 becomes extremely low, whereby the exhaust gas can be easily treated and there is no risk of air pollution or the like.

A reduction processing chamber 7 which is long in the front-rear direction is
Since the indirect heating is performed from substantially the entire surface, the heat transfer surface is extremely large, and the inside of the reduction processing chamber 7 is uniformly heated. As a result, the inside of the reduction chamber 7 is prevented from being locally heated to a high temperature, so that the tin oxide can be satisfactorily reduced with almost no loss of vaporization of tin.

In addition, since the vaporization loss of tin is well suppressed, it is not necessary to perform submerging with slag (if impurities such as iron are removed from the raw material in advance,
No slag for refining is required.) Therefore, it is not necessary to raise the temperature in the reduction treatment chamber 7 to a temperature (about 1200 ° C.) at which the fluidity of the slag can be secured, and as a result, a virtuous circulation is realized in which the loss of vaporization of tin is further prevented.

Further, since the reduction processing chamber 7 is indirectly heated by the combustion gas introduced into the heating chamber 8,
The combustion gas component does not affect the reducing atmosphere in the reduction processing chamber 7. That is, it is possible to control the heating temperature independently of the combustion gas component. Therefore, it is possible to control the heating temperature to an optimum temperature for the reduction reaction while maintaining a predetermined reducing atmosphere, and it is possible to efficiently perform the tin oxide reduction treatment. The heating temperature can be easily controlled by setting the heating burner air-fuel ratio in the combustor 18 or the like.

The reduced molten metal tin drops between the particles of the raw material / reducing agent mixture 16 in the reduction processing chamber 7 and accumulates at the bottom of the reduction processing chamber 7. When the reduction treatment for a plurality of batches is completed, the tapping port 11 is opened to melt the molten tin, and the molten tin is poured into the mold and collected by the ladle 22 or the like.

The exhaust gas discharged from the heating chamber 8 to the exhaust system 20a through the exhaust port 20 is heat-exchanged in the raw material tin oxide and / or reducing agent drying / preheating equipment I, so that the tin oxide raw material and the reducing agent are removed. Used for preheating or drying. Also,
The exhaust gas can be guided to the metal tin melting facility J and the heat can be used for heating. If the raw material containing tin oxide or the reducing agent is preheated or dried using the heat of the exhaust gas, and these materials are used in the next reduction treatment, the reduction reaction time can be reduced. In particular, when a graphite-based refractory material or a silicon carbide-based refractory material which is easily oxidized and damaged by water vapor is used as a material of the refractory partition wall 6 of the reduction treatment chamber 7, the raw material containing tin oxide and the By preheating and drying the agent, a remarkable effect of preventing damage to the refractory material can be obtained. Further, there is an effect that damage to the refractory material due to heat shock or thermal stress when these materials are charged into the reduction treatment chamber 7 can be reduced.

If the start and end of the reduction processing in the two reduction processing chambers 7 and 7 are shifted with an appropriate time difference, the supply operation of the raw material / reducing agent mixture 16 and the tapping operation need not be performed at the same time. Therefore, there is a merit that the work can be efficiently performed by fewer workers. For example, as shown in FIG. 8, during the reduction processing step B by one reduction processing chamber 7A after the raw material feeding step A is completed, the raw material feeding step A to the other reduction processing chamber 7B is performed.
In addition, during the reduction process B by the other reduction processing chamber 7B, the setting is made such that the tapping work C from the one reduction processing chamber 7A is performed. While maintaining such a relationship, the reduction process is continuously performed without interruption.

It should be noted that the present invention is not limited to the above-described embodiment, and can be appropriately improved and changed without departing from the basic principle of the present invention. For example, in the above embodiment, a pair of independent reduction processing chambers 7 and 7 are installed in the furnace main body 2, but the number of reduction processing chambers 7 to be installed depends on the size and shape of the furnace main body 2. Can be set. However, in order to improve the heating efficiency and the reduction treatment efficiency while securing the reduction treatment amount of tin oxide, it is preferable to set the number of the reduction treatment chambers 7 to two or more. By doing so, the amount of reduction processing shared by each reduction processing chamber 7 is reduced, so that the thermal efficiency of indirect heating from the heating chamber 8 is improved, and the raw material / reducing agent mixture 1 is reduced as described above.
The supply operation 6 and the tapping operation 6 can be performed separately for each reduction processing chamber 7 without duplication, and the reduction processing efficiency can be improved. When a plurality of reduction processing chambers 7 are provided, each reduction processing chamber 7 may be connected to each other without being independent.

Further, the shapes of the furnace body 2 and the reduction processing chamber 7 are not limited to the rectangular box shape in the above embodiment, but may be, for example, a crucible shape having a circular cross section or a cylindrical shape. Such a circular cross section has the advantage that the heat efficiency can be improved by passing the heating gas while spirally turning it along the outer periphery of the reduction processing chamber 7.

The structure of the heating chamber 8 is also optional, and can be appropriately designed according to the shape and the number of the reduction processing chambers 7 to be installed. However, in order to improve the heat transfer area, it is preferable to surround the entire or substantially entire surface of the reduction processing chamber 7. Of course, when a plurality of reduction processing chambers 7 are provided, the heating chambers 8 may be divided into a plurality of heating chambers instead of a series.

Further, the raw material supply device 3 which is a means for supplying the raw material and the reducing agent to the reduction processing chamber 7 is not limited to the above embodiment. For example, when a raw material containing tin oxide and a reducing agent are mixed and supplied to the reduction processing chamber 7, as shown in FIG. 9, the tin oxide raw material storage hopper 50 and the reducing agent (for example, coke) storage hopper 51 are used. After taking out necessary amounts into the respective weighing hoppers 52 and 53 and weighing them, they are put into a mixer (mixer) 54 and uniformly mixed in advance. Then, it is also conceivable to carry the raw material to the raw material hopper 15 immediately above the reduction processing chamber 7 and charge it into the reduction processing chamber 7. Of course, it is also possible to omit the transport bag 55 and the raw material hopper 15 to make the mixture continuous, and to directly charge the mixture in the mixer 54 into the reduction treatment chamber 7.

For example, FIGS. 5 and 6 show a case where the raw material hopper 15 is of a fixed type.
It is also possible to employ a movable hopper in which a rail is laid on the base 3 and wheels are provided on the support base 14 to form a movable base. When the movable type is used, each hopper 15 in which the tin oxide raw material and the reducing agent are separately stored is moved, so that the tin oxide raw material and the reducing agent are alternately layered and mounted in the reduction processing chamber 7. It can be easily inserted.

Further, as described above, the heat source supply device 4 serving as a means for supplying a heat source to the heating chamber 8 is configured to supply the combustion gas generated in the dedicated combustor 18 as described above, In order to supply waste heat or surplus heat such as exhaust gas generated in other equipment to the heating chamber 8 directly or by heating, provided that the inside of the furnace 7 can be indirectly heated to a temperature higher than the temperature at which the reduction reaction occurs. Is also good. Alternatively, the partition wall 6 and thus the inside of the reduction chamber 7 may be heated by directly bringing the electric heater into the heating chamber 8 as a heat source. Further, the main body of the partition wall 6 may be formed of a carbon-based refractory material such as graphite or silicon carbide, and may be heated by induction heating means. In this case, for example, the partition wall 6 made of a carbon-based refractory material is caused to generate heat by an alternating current by induction heating means, and the inside of the reduction treatment chamber 7 is indirectly heated by using the heat as a heat source to cause a reduction reaction.

In the following, the present invention was carried out to examine the processing conditions in the reduction treatment of tin oxide of the present invention, for example, the ratio of the amount of tin oxide to the raw material in the raw material, the effect of the reduction reaction temperature, the effect of the mixed state of the raw materials, and the like. The experiment will be described. (Example 1) [About ratio of tin oxide and amount of reducing agent in raw material] (1) Raw material: White sludge having a water content of 10% was used as a raw material containing tin oxide. As a reducing agent, coke (a carbon C content ratio of 90%) which is a typical solid carbonaceous reducing agent is used.
Was used. The water content of this white sludge was removed, and the content of tin oxide SnO ₂ obtained by quantitative analysis was 77.5% (that is,
(Moisture 0%, tin oxide Sn02 ₂ about 78%). In addition,
All ratios represent% by weight (hereinafter the same).

(2) Processing apparatus: a reduction processing chamber having a fire-resistant wall, having a diameter of 65 mm, a height of 150 mm, and an internal volume of 49
A 7 cc magnesium oxide crucible was used. A test furnace as shown in FIG. 10 was used as means for externally heating the crucible as the reduction processing chamber. This furnace is provided with a reaction tube T with a lid made of stainless steel for accommodating the crucible R and a heating element F for heating the reaction tube T from outside in a furnace.

(3) Processing Method The crucible R charged with the raw materials is housed in the reaction tube T, and the crucible R is closed.
The reduction reaction is performed by heating with the heating element F while passing nitrogen gas through the inside of the reaction tube T. At predetermined time intervals, the gas in the reaction tube T is sampled and subjected to gas analysis, and CO in nitrogen gas (N ₂ ) is analyzed.
% And CO ₂ % as well as the recovery of tin Sn from white sludge. In addition, the experiment is performed separately by charging the raw materials into the crucible R, and comparing the results.

(4) Reduction treatment conditions Raw material charging state: As shown in FIG. 10, raw white sludge S and coke C were charged alternately in a crucible R in layers. Total amount of white sludge / total coke = 300 g / 10-
The range was 120 g.

(5) Processing Result FIG. 11 shows the relationship between the coke amount and the Sn recovery rate as the processing result. From this experiment, it was found that as the amount of coke increases, the amount of unreacted coke residue increases, so that post-treatment such as exhaust treatment and residue treatment becomes difficult. As for the Sn recovery rate, as is clear from FIG. 11, the recovery rate increases in a range where the coke amount is small,
It was found that as the amount of coke increases beyond a certain amount, the Sn recovery rate conversely decreases. This is presumably because the more coke residue, the more difficult it is to separate metallic tin Sn from the residue and the residue.

Here, when the ratio of the total amount of white sludge / the total amount of coke is converted into the ratio of the amount of tin oxide to the amount of carbon, the content of tin oxide in white sludge is 78%, and the content of carbon in coke is 90%. As%, it is as follows.

Tin oxide: carbon = 100: 3.8-46.2 Therefore, based on the above results, the mixing ratio between the amount of tin oxide in the raw material and the amount of carbon in the reducing agent was determined based on FIG. This will be discussed with reference to FIG.

From the above experiment, when the amount of tin oxide is set to 1, the amount of carbon required to recover at least 85% of tin Sn in the tin oxide is in the range of 0.08 to 0.23. The amount of carbon required for recovering 70% or more of the tin Sn is 0.0% or less.
It is in the range of 4-0.3.

That is, in the present invention, the mixing ratio of tin oxide SnO ₂ in the raw material and carbon C in the reducing agent mixed therein is tin oxide: carbon = 100: 8 or more when the recovery rate of tin is 85% or more. 23 (mass ratio).

However, in practice, it may be acceptable for the tin recovery to fall below 85%. Therefore, from a practical point of view, the ratio of tin oxide of the present invention to carbon as a reducing agent is set to be tin oxide: carbon = 100: 4 to 30 at which a tin recovery rate is 70% or more. When the carbon ratio is out of the range of 4 to 30, the recovery rate of tin is too low or the coke residue treatment becomes difficult, which is uneconomical.

(Example 2) [Reduction reaction temperature and loss of vaporization of tin] (1) Raw material: Same as in Example 1.

(2) Processing device: Same as in the first embodiment. (3) Processing method This is almost the same as in the first embodiment.

However, the raw material charging state in the crucible R is the same as in Example 1, the furnace temperature is set in the range of 600 to 1200 ° C., and the results are compared. (4) Reduction treatment conditions 1) Raw material charged state: Same as in Example 1.

2) Atmosphere: N ₂ (10 Nl / min) 3) Temperature: 600 to 1200 ° C. (5) Treatment result FIG. 13 shows a plot of measured values of reaction temperature and Sn recovery as treatment results. Show. FIG. 14 shows the reduction reaction rate at each processing temperature calculated from the gas analysis result (deoxygenation amount per unit time, g / min).

From these results, it was found that the processing temperature was 600.degree.
In the range of 00 ° C., the reduction reaction time is insufficient, and the Sn recovery rate is less than 70%, which is a low value. Processing temperature is 900
It is understood that when the temperature exceeds ℃, the reduction reaction proceeds promptly. In general, at 900 ° C. or higher, the reduction reaction is accelerated by a solution loss reaction. That is, if there is a necessary and sufficient coke in the temperature range where the solution loss reaction occurs, CO generated by the reduction reaction
₂ becomes CO, and the CO gas causes a reduction reaction again.

In particular, in FIG. 13, the Sn recovery rate sharply rises in the processing temperature range of 1000 to 1100 ° C., but thereafter, the recovery rate starts to decrease and 1200
After that, the Sn recovery rate decreases rather than the case of 1100 ° C., although the reduction reaction rate sharply increases as shown in FIG. The cause may be a loss of vaporization of the tin component.

The present inventors have determined that the ratio of the theoretical vaporization loss of the tin component in the reduction reaction of tin oxide SnO ₂ is as follows:
The temperature was calculated based on the vapor pressure and plotted on the graph of FIG. Incidentally, for example, regarding the vapor pressure at each temperature of SnO, the following equation (page 134) described in the literature: "Metal oxides and composite oxides" by Kozo Tabe and others (Kodansha, April 20, 1978, p. 134). It can be calculated in 1).

LogP (mmHg) = 10.775− (13161 / T (K)) (1) On the other hand, regarding the amount of vaporization loss, Sn in 1 kg of SnO ₂
Since the amount is 788 g and the O amount is 212 g, the amount of CO ₂ generated by carbon reduction is 290 g.

Therefore, the tin component (Sn or SnO)
Assuming that the vapor pressure of ₂ ) is x (atm), that of CO ₂ is 1-x (atm), so that the molar fraction of both vapors is 1-x: x. Therefore, the evaporation loss of the tin component can be obtained by the following equation (2).

{290/44 (mol) / (1−vapor pressure)} × vapor pressure × 119 (g / mol) (2) FIG. 15 shows the theoretical tin component loss ratio calculated from the above equation ( %)
2 is a plot of the relationship between the temperature and the reaction temperature. FIG.
When the reaction temperature exceeds 1000 ° C., the theoretical tin component loss ratio starts to increase, and at 1200 ° C. or higher, it rapidly increases. From this, the upper limit of the treatment temperature in the tin oxide reduction treatment of the present invention is 1300.
C., but 1200 C. is preferable. If the aim is to reduce the vaporization loss, the temperature is desirably 1150 ° C. or lower. (Example 3) [Comparison between mixed charging and layered charging of raw material tin oxide and reducing agent] (1) Raw material: Same as in Example 1.

(2) Processing apparatus: Same as in the first embodiment. (3) Processing method This is almost the same as in the first embodiment.

However, the raw material charged state in the crucible R was such that white sludge and coke were completely mixed in advance and charged in the crucible, and white sludge and coke were alternately charged in three layers in layers. There are two types of things.

This is reduced at a furnace temperature of 1100 ° C., and the results are compared. (4) Reduction treatment conditions 1) Raw material charged state: For mixing, layered means that white sludge has three layers of 100 g for each layer, and coke has one layer for each layer.
0 g is made into three layers, and alternately into a total of six layers.

2) Atmosphere: N ₂ (10 Nl / min) 3) Temperature: 1100 ° C. (5) Treatment results FIG. 16 shows a comparison of reduction reaction rates for each charged state of raw materials calculated from the results of gas analysis.

From these results, it can be seen that the reduction reaction proceeds faster in the mixed charging than in the layered charging. This is because the contact area with the reducing gas is large. On the other hand, the amount of Sn recovered is better in layered charging, but the difference between them is small.

[0095]

As described above, according to the method for reducing tin oxide of the present invention, the raw material containing tin oxide and the reducing agent are indirectly heated in the reduction processing chamber, so that Fe is mixed. High purity, low loss of tin vaporization, high yield, low cost with no waste gas treatment and low furnace wear, low CO gas emission, safe and There is an effect that metal tin can be easily recovered without using slag.

According to the tin oxide reduction treatment apparatus of the present invention, a reduction treatment chamber and a heating chamber divided by a refractory partition wall are provided, and an exhaust port, a tap hole, tin oxide and carbon are provided in the reduction treatment chamber. And a means for indirectly heating the tin oxide raw material and the reducing agent in the reduction processing chamber, so that the above-described method for reducing tin oxide of the present invention is efficiently implemented. The effect that it can do is obtained.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating a method for reducing tin oxide according to the present invention.

FIG. 2 is a conceptual diagram illustrating a method for reducing tin oxide according to the present invention.

FIG. 3 is a conceptual diagram illustrating a method for reducing tin oxide according to the present invention.

FIG. 4 is a conceptual diagram illustrating a method for reducing tin oxide according to the present invention.

FIG. 5 is a cross-sectional view of one embodiment of a tin oxide reduction treatment apparatus according to the present invention.

6 is a sectional view taken along line VI-VI of FIG.

[7] the equilibrium constant for the carbothermic reduction of SnO ₂ (Pco /
Pco ₂₎ and a diagram showing the relationship between the temperature.

FIG. 8 is a view for explaining an aspect of a tin oxide reduction treatment operation by the apparatus shown in FIG. 5;

FIG. 9 is a schematic diagram illustrating another embodiment of charging raw materials.

FIG. 10 is a schematic view of a test furnace used for a tin oxide reduction treatment.

FIG. 11: Sn by coke amount in tin oxide reduction treatment
It is a figure showing the recovery.

FIG. 12 is a diagram showing the relationship between the ratio of the amount of carbon / tin oxide in the tin oxide reduction treatment and the Sn recovery rate.

FIG. 13 is a diagram showing a relationship between a reaction temperature and a Sn recovery rate in a tin oxide reduction treatment.

FIG. 14 is a diagram showing a transition of a treatment temperature and a reduction reaction rate in a tin oxide reduction treatment.

FIG. 15 is a diagram showing the relationship between the ratio of the theoretical vaporization loss of the tin component and the reaction temperature in the tin oxide reduction treatment.

FIG. 16 is a diagram showing a relationship between a raw material charging state and a reduction reaction rate in a tin oxide reduction treatment.

FIG. 17 is a diagram illustrating an example of a conventional tin oxide reduction treatment process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reduction processing apparatus 4 Heating means (heat source supply apparatus) 6 Partition wall (fireproof wall) 7 Reduction processing chamber 8 Heating chamber 9 Exhaust port 10 Supply port 11 Hot water outlet

[Procedure amendment]

[Submission date] May 15, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 12

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction contents]

When the indirect heating in the present invention is performed by using a heating burner B as shown in FIG.
Utilizing the heat of the exhaust gas discharged out of the furnace, it can be used for drying and preheating of the raw material tin oxide and / or reducing agent. As the equipment I for the drying or preheating, if a raw material charging equipment is used, heat loss and dust generation can be prevented. Alternatively, a dryer and a preheater can be separately installed and used. In any case, if the raw material or the reducing agent containing tin oxide is preheated and / or dried using the heat of the exhaust gas,
Next, the time required to raise the temperature of these materials to a predetermined temperature or evaporate moisture in the reduction treatment chamber is reduced, thereby reducing the reduction reaction time and improving the thermal efficiency of the reduction treatment. there Ru. Also, by previously preheating the raw materials and reducing agents, including tin oxide, an effect of reducing the damage to the refractory material by heat shock or thermal stress at the time of charging these materials to reduction treatment chamber.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0039

[Correction method] Change

[Correction contents]

[0039] The refractory of the partition walls is good to basic refractories (claim 12). The refractories that make up the furnace provide insulation
The target is acid refractory such as SiO ₂ or Al ₂ O
General oxides including neutral refractories such as ₃ , CrO ₃
Although refractory may be used, Sn, SnO, SnO ₂ such as a partition wall may be used.
It is desirable to use a basic refractory for the contacting parts.
No. In consideration of SnO penetration force is a basic oxide to various basic refractories, among others, we have to <br/> preferred those magnesium oxide MgO system with a penetration moderate.

Claims (14)

[Claims] 1. An oxidation method, wherein a tin oxide-containing raw material and a reducing agent are indirectly heated by a heating means in a reduction treatment chamber having a fire-resistant wall to reduce the tin oxide to a metal. Tin reduction treatment method. 2. The method for reducing tin oxide according to claim 1, wherein the reducing agent is a solid carbonaceous reducing agent. 3. The tin oxide according to claim 2, wherein the raw material containing tin oxide and the solid carbonaceous reducing agent are charged alternately in layers in the reduction processing chamber and heated. Reduction treatment method. 4. The tin oxide according to claim 2, wherein the raw material containing tin oxide and the solid carbonaceous reducing agent are mixed in advance and charged into the reduction treatment chamber and heated. Reduction treatment method. 5. The reducing gas atmosphere according to claim 1, wherein the reducing agent is a gas reducing agent, and the gas reducing agent is blown into a raw material containing tin oxide in the reduction processing chamber to form a reducing gas atmosphere. A method for reducing tin oxide. 6. The method according to claim 5, wherein the gas reducing agent is a gas carbonaceous reducing agent. 7. The ratio of the amount of tin oxide in the raw material containing tin oxide and the amount of carbon in the reducing agent charged into the reduction treatment chamber is tin oxide: carbon = 100: 4 to 30 (mass ratio). 7. The method for reducing tin oxide according to any one of claims 1 to 6. 8. The reduction of tin oxide according to claim 1, wherein the temperature of the reduction reaction of tin oxide in the raw material containing tin oxide is set to 600 to 1300 ° C. Processing method. 9. A high-temperature inert gas is supplied to a reduction processing chamber having a refractory wall and a raw material containing tin oxide is supplied to the reduction processing chamber under a reducing gas atmosphere. Wherein the tin oxide is reduced by indirectly heating in combination with the heating means. 10. The tin oxide according to claim 1, wherein the tin oxide-containing raw material is a sludge mainly composed of tin oxide generated in an electroplating step. Reduction treatment method. 11. A furnace used for reduction treatment of tin oxide, wherein the inside of a furnace body is divided into a reduction treatment chamber and a heating chamber by a refractory partition wall, and an exhaust port, a tap hole, and a discharge port are provided in the reduction treatment chamber. A tin oxide reduction treatment apparatus comprising: a supply port for tin oxide and a reducing agent; and a heating unit for indirectly heating the tin oxide and the reducing agent in the reduction treatment chamber. 12. The tin oxide reduction treatment apparatus according to claim 11, wherein the refractory partition wall is a basic refractory or a non-oxide refractory. 13. The tin oxide reduction treatment apparatus according to claim 11, wherein a plurality of the reduction treatment chambers are provided in the furnace body. 14. The tin oxide reduction treatment apparatus according to claim 11, wherein pretreatment of tin oxide and / or a reducing agent that exchanges heat with exhaust gas discharged from the heating chamber is performed. Or a tin oxide reduction treatment apparatus characterized by adding a drying means.