WO2018207971A1 - Method for recovering high purity tin and producing hydrogen using methane gas reduction mthod - Google Patents

Abstract

The present invention relates to a method for recovering high purity tin, and at the same time, producing hydrogen from tin oxides using a methane gas, and by using a methane gas reduction method which combines a tin recovery process and a hydrogen producing process, high purity tin may be stably recovered and at the same time, hydrogen which is a novel clean energy source may be produced without generating environmental pollutants such as carbon dioxide, sulfur dioxide and nitrogen oxide from methane gas and tin oxides. In addition, by recycling waste materials including tin oxides, which are generated in various industries, according to the present invention, environmental pollution may be prevented, and by stably recovering high purity tin, which is an expensive metal, and at the same time, by significantly decreasing hydrogen production costs, economic feasibility is increased and so efficient use of resources may be achieved.

Description

High-purity tin recovery and hydrogen production method using methane gas reduction

The present invention relates to a high-purity tin recovery and hydrogen production method using the methane gas reduction method, more specifically by using a methane gas as a reducing agent dry tin reduction of the tin oxide to recover high-purity tin without the generation of environmental pollutants and at the same time a methane reducing agent A method for producing hydrogen from gas as a byproduct.

Tin is a carbon group element belonging to the 5th cycle of group 14 of the periodic table. The element symbol is Sn, and it is widely used after casting because of its excellent malleability, ductility and corrosion resistance and easy melting. In particular, tin plays an important role as a lead-free solder in the electronic components and materials industry.It produces LED TVs, alloy materials, plating materials, contact materials for electrical and electronic products, transparent electrodes, flat glass and LCD panel glass materials. It is used as a core material in processes, and its usage is increasing.

However, tin resources are concentrated in some countries, such as Southeast Asia, and strategically refining only in these countries, resulting in unstable international supply and demand and high price fluctuations. Currently, tin's international trading price is $ 21,000 / ton, three times that of copper and ten times that of aluminum. Therefore, in recent years, the importance of techniques for recovering tin from waste materials containing tin has been highlighted, and related technologies have attracted attention. Until now, methods such as melting, dry reduction, solvent extraction, and wet reduction have been studied and applied for tin reduction.

Although the technique of recovering metal tin from tin oxide by dry reduction method or wet reduction method is commercially available, the recovery of tin from waste solder, scrap or sludge having a relatively high tin content is most common. Since large amounts of slag, chemical solution wastewater and carbon dioxide are generated to cause environmental pollution, there is a need for a more environmentally friendly clean technology-based tin recovery method.

Regarding the dry reduction method, Korean Patent No. 10-1619340 discloses a method for recovering tin from tin-containing dross using a carbon-based material and a dry reduction process, but also due to slag and a large amount of carbon dioxide emission. Not free from environmental pollution

Regarding the wet reduction method, Korean Patent No. 10-1431532 relates to a method for separating and recovering useful metals in a wasteless lead-free solder. The waste lead-free solder is added to a solvent containing a solubility enhancer to leach tin to recover tin. Although the method is proposed, in addition to the generation of a large amount of chemical solution waste water, there is a problem in that the treatment cost is high, the purification time is long, and the consumption of reagents used is large.

In addition to researches to improve the recovery rate of tin, high-purity tin recovery technology is currently being researched at home and abroad, but in addition to the above-mentioned problems of dry reduction method or wet reduction method such as pollutant emissions and waste residues generated during the process, thermal efficiency, economical efficiency and expansion Due to the low performance, there is a demand for technology development to sufficiently improve this.

On the other hand, in recent years, new energy technologies have attracted attention due to environmental pollution and depletion of petroleum resources. As one of such new energy technologies, a fuel cell converts chemical energy into electrical energy by electrochemically reacting hydrogen and oxygen, and has been actively researched for practical use as a civil, industrial, or automobile because of its high energy use efficiency. .

As the hydrogen source of the fuel cell, petroleum hydrocarbons such as liquefied natural gas, city gas, synthetic liquid fuel, petroleum naphtha, kerosene, etc., mainly composed of methanol and methane, are used. As a manufacturing method, there is a method of using a steam reforming treatment or a self thermal reforming treatment, a partial oxidation reforming treatment, or the like in the presence of a catalyst.

However, the method of using water vapor as a catalyst has a disadvantage in that the process is very complicated and carbon dioxide is generated together with hydrogen as a reaction result. In addition, due to the nature of the reaction, even in the presence of the catalyst is an endothermic reaction that must be made at a high temperature of about 700 to 1,200 ℃ need a special reforming furnace, there is a problem of the additional cost comes from the life and durability of the catalyst exposed to high temperature. In the partial oxidation reforming of hydrocarbons, a special partial oxidation furnace is required, and a large amount of soot is generated in accordance with the reaction, so that not only its treatment but also a problem that the catalyst is easily deteriorated occurs. The high temperature pyrolysis process using plasma has the advantage that carbon dioxide is not generated during the methane pyrolysis process, but the hydrogen production cost increases because a large amount of energy is required for the pyrolysis of methane.

Therefore, in order to utilize hydrogen as an energy source, an innovative method is needed to compensate for the disadvantages of existing hydrogen production processes.

Therefore, the inventors of the present invention, while studying a method for recovering high-purity tin from tin oxide and a method for increasing the productivity of hydrogen, a new clean energy resource, invented a methane gas reduction method combining a tin recovery process and a hydrogen production process. By using this method, it is possible to stably recover high-purity tin without generating environmental pollutants such as carbon dioxide, sulfur dioxide, and nitrogen oxide from tin oxide, and at the same time, to construct a process capable of efficiently producing hydrogen, a new clean energy resource, to complete the present invention. It became.

One object of the present invention is to provide a method for recovering high purity tin from tin oxide using methane gas and simultaneously producing hydrogen.

In order to solve the above technical problem, the present invention provides a method for recovering high-purity tin and producing hydrogen as a byproduct by injecting methane gas into the reactor to which tin oxide is added and then reducing.

Specifically, after the methane gas is injected into a reactor into which tin oxide is added and the reduction reaction is performed at 600 to 1,500 ° C., methane gas is obtained by obtaining tin and hydrogen gas generated through a reduction reaction. It provides a high-purity tin recovery and hydrogen production method using.

The reaction scheme used for the high purity tin recovery and hydrogen production is represented by the following Chemical Formula 1.

Injecting methane gas into the reactor into which tin oxide is added and mixing them to reduce the reaction (reaction process) by using gaseous methane gas rather than a solid reducing agent to increase the efficiency of the reduction reaction, carbon and hydrogen By utilizing the characteristics of methane consisting of multi-stage reduction of carbon and hydrogen to effectively reduce the tin oxide to recover tin efficiently and at the same time to produce hydrogen by the decomposition of methane gas as a by-product.

In the present invention, the tin oxide is not particularly limited thereto, but may occur in LED TV, alloy materials, plating materials, contact materials of electrical and electronic products, transparent electrodes, flat glass, and LCD panel glass materials production or disposal processes. Waste containing tin oxide and tin oxide salt, and the like, and any of those containing tin oxide (tin oxide) or tin oxide salt in this oxidized form may be used.

In one specific embodiment, in the case of using the waste containing tin oxide or tin oxide salt, a pretreatment process such as pulverization, crushing, calcination of organic materials, filtration and separation of impurities is performed to increase the efficiency of the process. can do.

In one specific embodiment, when the waste is a process sludge, wastewater sludge, or waste liquid, the pretreatment process is not particularly limited thereto, but impurities such as sand, soil, plastic, and waste residues are removed using a filtration membrane, a separator, or a screen. This can be done by.

The methane gas of the present invention contains 80 to 99% of methane. It is preferably 85 to 98.5%, more preferably 90 to 98%. When the content of methane is less than 80%, the efficiency of the reduction reaction in the tin oxide and the reactor is reduced to significantly reduce the recovery rate and hydrogen production rate of tin, and when exceeding 99%, excessive costs and processes are consumed in the manufacturing process. This reduces efficiency.

The mixing ratio of the tin oxide and methane gas is 1: 1 to 6 mol. When the ratio of methane gas is less than 1 mol in the mixing ratio, it is possible to recover pure tin and produce hydrogen, but a large amount of carbon dioxide (CO ₂ ) is generated, and when the ratio of methane gas exceeds 6 mol, carbon dioxide (CO ₂ The amount of) is very low, but a large amount of unreacted methane gas is present, which reduces the efficiency of the process.

The reaction process of the present invention is carried out at 600 to 1,500 ℃. Preferably proceeds to 700 to 1,400 ℃, more preferably to 800 to 1,000 ℃. When the temperature is less than 600 ℃, the reduction reaction of the mixed reactant tin oxide and methane gas does not occur well, and the recovery rate of tin and the productivity of hydrogen decreases, and when the temperature exceeds 1,500 ℃, the increase in tin recovery due to the temperature increase is almost This reduces efficiency in terms of process time and cost, and leads to carbon deposition problems due to the direct decomposition of methane, thereby reducing the purity of recovered tin.

After the reaction process is completed, high-purity tin and hydrogen gas may be obtained by separating each from the reactor.

The method of recovering high-purity tin from tin oxide and simultaneously producing hydrogen using methane gas of the present invention is invented by fusing tin recovery process and hydrogen production process, which are different fields, and methane gas using methane gas reduction method. It is possible to stably recover high-purity tin from hydrogen and tin oxide without generating environmental pollutants such as carbon dioxide, sulfur dioxide, and nitrogen oxide, and to produce hydrogen, a new clean energy resource. In addition, by recycling the waste containing tin oxide generated in various industries according to the present invention to prevent environmental pollution, to recover the tin as a high value metal with high purity and stable and at the same time significantly lower the cost of hydrogen production to increase the economic efficiency Efficient use of resources can be achieved.

Figure 1 shows the chemical reaction of tin recovery and hydrogen production technology of the present invention fused methane gas reforming and reduction of tin oxide.

Figure 2 schematically shows a high purity tin recovery and hydrogen production method using a methane gas reduction method according to an embodiment of the present invention.

Hereinafter, examples and the like will be described in detail to help understand the present invention. However, embodiments according to the present invention can be modified in many different forms, the scope of the invention should not be construed as limited to the following examples. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art.

Example  1: High purity tin recovery and hydrogen production using methane gas reduction

The tin oxide ingot was pulverized into powder, and 25 g of tin oxide powder was put in an alumina boat and placed in a quartz tube of a reduction furnace, as shown in FIG. 2, and both sides of the quartz tube were sealed with jig for injection and collection of gas. After sealing, the temperature of the reduction furnace was raised to 1000 ° C, and methane gas was injected into one of the quartz tubes. At this time, the methane gas was controlled using a mass flow controller (MFC), and in the first embodiment, methane gas was injected into the reactor in an amount of 250 sccm (standard cubic centimeter per minute). The mixing ratio (mole fraction) of tin oxide (SnO ₂ ) and methane (CH ₄ ) was 1: 3.7 mol under methane gas injection conditions of 250 sccm. In order to capture carbon monoxide, carbon dioxide, and unreacted methane gas, which may be generated during the reaction, gas was collected by installing a gas bag opposite the methane gas inlet of the quartz tube. The tin reduction reaction by methane gas was carried out for 1 hour, and methane gas remaining in the reactor after the reaction was discharged out of the reactor and burned.

Test Example  1: Component Analysis of Reduced Tin

The reduced tin of Example 1 was subjected to component analysis based on KS D 1720 and the results are shown in Table 1 below.

element	Furtherance(%)	Test Methods
Sn	99.34	KS D 1720: 1994
Pb	Not detected	KS D 1720: 1994
Sb	0.13	KS D 1720: 1994
As	0.001	KS D 1720: 1994
Cu	0.49	KS D 1720: 1994
Fe	0.04	KS D 1720: 1994

As shown in Table 1, the elements to be detected were Pb, Sb, As, Cu, Fe, including Sn, and were analyzed to be 99.34% of Sn and 0.13%, 0.001%, and 0.49 of Sb, As, Cu, and Fe as impurities, respectively. %, 0.04% was present. That is, it was confirmed that 99.34% of high purity tin can be recovered by the reduction process of tin oxide by methane gas.

Test Example  2: exhaust gas composition and concentration analysis

Components and concentrations of the exhaust gas collected in the gas collection bag of Example 1 were analyzed using gas chromatography (GC-TCD) and mass spectrometry (QMS), and the results are shown in Table 2 below.

ingredient	density( % )
H 2	83.5
CO	14.0
CH 4	1.7
CO 2	0.4

As shown in Table 2, the concentrations of hydrogen, carbon monoxide, methane, and carbon dioxide were 83.9%, 14.0%, 1.7%, and 0.4%, respectively. In other words, when the reduction process of the tin oxide by methane proceeds, it was confirmed that a hydrogen mixture gas having a hydrogen concentration of 83.9% was obtained as a byproduct.

Comparative example  1: High purity tin recovery and hydrogen production using excess methane

Tin oxide powder was reduced by the same method and process as in Example 1. However, methane gas was injected at 416 sccm so that the mixing ratio (mole fraction) of tin oxide (SnO ₂ ) and methane (CH ₄ ) was 1: 6.1 mol.

Test Example  3: Component Analysis of Reduced Tin

The reduced tin of Comparative Example 1 was analyzed on the basis of KS D 1720 and the results are shown in Table 3 below.

element	Furtherance(%)	Test Methods
Sn	99.88	KS D 1720: 1994
Pb	0.013	KS D 1720: 1994
Sb	Not detected	KS D 1720: 1994
As	Not detected	KS D 1720: 1994
Cu	0.11	KS D 1720: 1994
Fe	Not detected	KS D 1720: 1994

As shown in Table 3, the elements to be detected were Sn, Pb, Sb, As, Cu, Fe, and Sn was analyzed as 99.88%, and Pb, Cu 0.013%, and 0.11% were present as impurities. That is, it was confirmed that 99.88% of high purity tin can be recovered by the reduction process of tin oxide with methane gas.

Test Example  4: Exhaust gas composition and concentration analysis

The exhaust gas collected in the gas collecting bag of Comparative Example 1 was analyzed by gas chromatography (GC-TCD) and mass spectrometry (QMS) to analyze the composition and concentration of the gas, and the analysis results are shown in Table 4 below.

ingredient	density( % )
H 2	43.8
CO	6.7
CH 4	0.2
CO 2	46.4

As shown in Table 4, it can be seen that the concentrations of hydrogen, carbon monoxide, methane, and carbon dioxide are 43.8%, 6.7%, 0.2%, and 46.4, respectively. That is, the injection amount of methane gas was increased to 416 sccm so that the mixing ratio (mole fraction) of tin oxide (SnO ₂ ) and methane (CH ₄ ) was 1: 6.1 mole. Appeared to increase. This result is due to the excessive supply of methane gas, which does not participate in the reduction reaction of tin oxide and increases the amount of methane gas discharged as it is in unreacted state.

Claims (5)

1. (S1) injecting and mixing methane gas (CH ₄ ) to the reactor in which tin oxide (tin oxide) is added;

   (S2) reducing the mixture of tin oxide and methane gas of the step (S1); And

   (S3) obtaining tin and hydrogen gas generated after the reduction reaction of step (S2);

   High purity tin recovery and hydrogen production method using a methane gas reduction method comprising a.
2. The method of claim 1,

   The tin oxide is tin, tin oxide salt of the oxidized form or a high purity tin recovery and hydrogen production method using a methane gas reduction method characterized in that the waste containing them.
3. The method of claim 1,

   The mixing ratio of the tin oxide and methane gas is 1: 1 to 6 mol high purity tin recovery and hydrogen production method using the methane gas reduction method.
4. The method of claim 1,

   Reduction of the step (S2) is a high purity tin recovery and hydrogen production method using the methane gas reduction method, characterized in that carried out at 600 to 1,500 ℃.
5. The method according to any one of claims 1 to 5,

   The methane gas is a high-purity tin recovery and hydrogen production method using a methane gas reduction method characterized in that the methane is contained 80 to 99%.

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