KR20250041217A - Manufacturing method of Ti briquettes for melting for Ti scrap recycling - Google Patents

Abstract

In recycling titanium scrap, the most important oxygen refining is implemented simultaneously in a briquette shape to facilitate recycling, and a method for manufacturing Ti briquettes capable of manufacturing titanium ingots or titanium powders using the briquettes is provided, comprising the steps of (a) providing titanium scrap as a by-product generated after titanium processing, (b) washing the titanium scrap provided in the step (a), (c) performing a hydrogenation heat treatment on the titanium scrap washed in the step (b), and (d) dehydrogenating the titanium hydrogenated in the step (c) to remove oxygen present inside the titanium, wherein the steps (c) and (d) are configured to be performed continuously, so that oxygen refining for recycling titanium scrap can be implemented simultaneously in a briquette shape.

Description

{Manufacturing method of Ti briquettes for melting for Ti scrap recycling}

The present invention relates to a method for manufacturing a Ti briquette for melting titanium (Ti) scrap recycling, and more particularly, to a method for manufacturing a Ti briquette which simultaneously implements oxygen refining, which is the most important process in recycling titanium scrap, in a briquette shape to facilitate recycling, and which can manufacture a titanium ingot or titanium powder using the briquette.

In general, titanium has an atomic number of 22 and an atomic symbol of 'Ti', and is also called 'titanium' or 'titanium'. It has the characteristics of high strength, high lightness, and whale-eating, so it has been mainly used in the aerospace industry, petrochemical equipment industry, etc.

In addition, its use as a structural material is expanding. That is, as a corrosion-resistant material, it is used in synthetic towers, various valves and pipes, measuring instruments, heat exchangers, etc. in fertilizer plants, and because titanium has excellent biocompatibility, it is light and strong, so its use is rapidly expanding to medical parts, eyeglass frames, wristwatches, golf clubs, etc. In terms of cost, it was also recognized as an expensive metal, but since titanium can maintain a long lifespan after application, it is currently recognized as an economical material when ultimately judged.

In the case of titanium, the process of extracting and processing it from ore requires a lot of cost, so there is a disadvantage in that the material is expensive. Therefore, recently, in order to solve the disadvantages of this titanium material, a technology is being developed to refine and recycle titanium raw materials such as titanium scrap or sponge.

In other words, titanium is a typical difficult-to-form material, and a large amount of scrap is generated when manufacturing parts. Therefore, recycling titanium scrap is essential to secure product price competitiveness. In fact, in advanced countries such as the US and EU that can produce titanium materials, about 60-70% of scrap is used when manufacturing titanium materials. Since titanium scrap is a material generated after product manufacturing, it is more likely to be contaminated than raw materials, and in particular, titanium reacts very highly with oxygen, so an oxygen refining method is very important in recycling titanium scrap.

Commercial pure titanium materials are classified into Grade 1 to Grade 4 according to the content of nitrogen, carbon, hydrogen, oxygen, and iron. In addition, recycling of titanium scrap is mainly done through melting, and in order to facilitate the melting process, it is recommended that titanium scrap be manufactured in the form of briquettes of a certain size.

The basic treatment for recycling titanium scrap is to remove titanium surface contamination through pretreatment processes such as washing and acid treatment. This method is effective in removing contamination from titanium scrap, but has the disadvantage of not being able to remove oxygen contained within the scrap.

In addition, titanium scrap recycling is mainly done through the melting method, and in this case, in order to use titanium scrap as a raw material, it is common to process it into a specific size, such as briquettes, and then input it. That is, when recycling Ti scrap, a mechanical process and time were required to prepare briquettes of a specific size along with chemical pretreatment during melting.

Examples of technologies for recycling titanium scrap as described above are disclosed in patent documents 1 to 3, etc.

For example, the following Patent Document 1 discloses a method for producing high-purity titanium powder, including the steps of collecting titanium for powder production, acid-washing and washing the collected titanium for powder production, performing hydrogenation heat treatment on the acid-washed and washed titanium for powder production in a hydrogen atmosphere, pulverizing the titanium for powder production that has undergone the hydrogenation heat treatment, classifying and selecting titanium powder having a desired particle size among the titanium powders, and dehydrogenating the titanium powder for powder production by heat-treating it in a hydrogen atmosphere, in order to improve the removal efficiency of oxides on the surface of the titanium powder.

In addition, the following patent document 2 discloses a method for recycling titanium scrap, including the steps of removing organic substances and sulfides in titanium scrap, oxidizing the titanium scrap to produce titanium oxide (step 1), pulverizing the produced titanium oxide and mixing it with carbon powder (step 2), and performing a carbonitriding reaction on the mixed titanium oxide to form titanium carbonitride (step 3), wherein the oxidation in step 1 is performed through heat treatment at a temperature of 750°C to 1600°C, and the mixing of the carbon powder in step 2 is performed in an amount of 43 to 47 parts by weight of carbon powder relative to 100 parts by weight of the produced titanium oxide.

Meanwhile, the following patent document 3 discloses a method for manufacturing a high-purity titanium material, including a first step of supplying a titanium raw material to a crucible accommodated inside a main chamber, a second step of supplying an inert gas and hydrogen to a plasma heating unit installed at an upper portion of the crucible unit to generate high-temperature hydrogen plasma to melt the titanium raw material and form a molten metal, a third step of detecting a hydrogen concentration and a water vapor concentration inside the main chamber, and a fourth step of controlling at least one of the amount of hydrogen supplied to the plasma heating unit or the amount of exhaust by an exhaust device unit that exhausts the inside of the main chamber based on the detected concentrations of hydrogen and water vapor.

Republic of Korea Patent Publication No. 10-2246722 (registered on April 26, 2021) Republic of Korea Patent Publication No. 10-1705174 (registered on February 3, 2017) Republic of Korea Patent Publication No. 10-2282577 (registered on July 22, 2021)

The technology disclosed in Patent Document 1, as described above, has a structure in which hydrogenation heat treatment is performed, a dehydrogenation process is performed on titanium powder after mechanical pulverization, and there is a problem in that the manufacturing process is complicated, and thus the manufacturing cost increases.

In addition, since Patent Document 2 crushes scrap by a physical method, there was a problem that it was difficult to form briquettes of a desired size for producing high-purity titanium ingots or titanium powder, and Patent Document 3 did not disclose a technology for processing waste Ti scrap into a desired size.

The purpose of the present invention is to solve the problems described above, and to provide a method for manufacturing Ti briquettes for dissolution for recycling Ti scrap, which can be processed into a desired size by utilizing the brittleness that occurs during hydrogenation of Ti, and then oxygen can be removed during dehydrogenation.

Another object of the present invention is to provide a method for manufacturing Ti briquettes for melting Ti scrap recycling, which can reduce manufacturing costs by simultaneously implementing oxygen refining for recycling titanium scrap into a briquette shape.

Another object of the present invention is to provide a method for producing Ti briquettes for melting for recycling Ti scrap, which can provide Ti material industry, i.e. Ti raw material and Ti metal products, by recycling waste Ti scrap.

In order to achieve the above object, the present invention provides a method for manufacturing a Ti briquette for melting for recycling titanium (Ti) scrap, which method comprises the steps of: (a) providing titanium scrap as a by-product generated after titanium processing; (b) washing the titanium scrap provided in the step (a); (c) performing a hydrogenation heat treatment on the titanium scrap washed in the step (b); and (d) dehydrogenating the titanium hydrogenated in the step (c) to remove oxygen present inside the titanium. The method comprises the steps of: (a) and (d) being performed sequentially.

In addition, in the method for manufacturing a Ti briquette for melting according to the present invention, the heat treatment in step (c) is characterized in that it is performed at a temperature of 550 to 650°C for 10 to 120 minutes under a hydrogen atmosphere in the chamber.

In addition, in the method for manufacturing a Ti briquette for melting according to the present invention, the dehydrogenation in step (d) is characterized in that it is performed at a temperature of 600 to 650°C under a vacuum atmosphere in the chamber.

In addition, in the method for manufacturing a Ti briquette for melting according to the present invention, the heat treatment in step (c) is characterized in that it is performed at a temperature of 650°C for 60 minutes under a hydrogen atmosphere in the chamber.

In addition, in the method for manufacturing a Ti briquette for melting according to the present invention, the removal of oxygen in step (d) is characterized in that it is performed by hydrogen atoms (H) dissociated from hydrogen molecules from oxidized titanium.

In addition, the titanium ingot of the present invention for achieving the above purpose is characterized in that it is manufactured by melting a briquette manufactured by the above-described method for manufacturing a Ti briquette for melting.

In addition, the titanium powder of the present invention for achieving the above purpose is characterized in that it is manufactured by melting briquettes manufactured by the above-described method for manufacturing Ti briquettes for melting.

As described above, according to the method for manufacturing a Ti briquette for melting for recycling Ti scrap according to the present invention, the effect of simplifying the manufacturing process of a high-purity titanium ingot or titanium powder can be obtained by simultaneously implementing oxygen refining for recycling titanium scrap into a briquette shape.

In addition, according to the method for manufacturing Ti briquettes for melting Ti scrap recycling according to the present invention, not only is briquettes manufactured more easily as a method for recycling Ti scrap, but also oxygen reduction during the refining process is possible.

In addition, according to the method for manufacturing a Ti briquette for melting for recycling Ti scrap according to the present invention, it is possible to obtain the effect of providing a method for recycling Ti scrap that is not recycled domestically.

Figure 1 is a process diagram for explaining the manufacturing process of Ti briquettes for melting Ti scrap recycling according to the present invention.
Figure 2 is a graph showing the hydrogen absorption behavior of titanium according to the hydrogenation heat treatment illustrated in Figure 1.
Figure 3 is a photograph to explain the self-fractured appearance of titanium after hydrogenation.
Figure 4 is a graph to explain the reducibility of titanium according to the hydrogen state.
Figure 5 is a drawing for explaining the behavior of hydrogen atoms and molecules during dehydrogenation.
Figure 6 is a graph for confirming the oxygen removal behavior during dehydrogenation through TG-MS measurement.
FIG. 7 is a drawing showing an example of a manufacturing device for manufacturing a titanium ingot by applying a Ti briquette manufactured according to the present invention.
FIG. 8 is a drawing showing an example of a manufacturing device for manufacturing titanium powder by applying Ti briquettes manufactured according to the present invention.

The above and other objects and novel features of the present invention will become more apparent from the description of this specification and the accompanying drawings.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Figure 1 is a process diagram for explaining a process for manufacturing Ti briquettes for melting Ti scrap recycling according to the present invention.

The Ti briquette for melting manufactured according to the present invention is provided for melting in order to recycle titanium (Ti) scrap, and in order to manufacture the Ti briquette, first, as shown in Fig. 1, titanium scrap after product manufacturing is prepared (S10). The titanium scrap is a by-product generated after titanium processing, and may include one or more metals selected from the group consisting of Ti, Ti-6Al-4V, Ti-Mo, and Ti-Ni. In addition, the titanium scrap may use a titanium sponge, or may be formed in the form of chips. In addition, the titanium scrap may include organic substances, oxides, and sulfides, such as lubricants, used during titanium processing.

Next, the titanium scrap prepared in the step S10 is washed (S20). The washing in the step S20 may be performed using an acid solution to remove impurities such as organic substances such as oil, oxides, and sulfides attached to the surface of the titanium scrap.

Next, the titanium scrap washed in step S20 is subjected to hydrogenation heat treatment (S30).

In the above step S30, the hydrogenation heat treatment can be performed at a temperature of 550 to 650° C. under a hydrogen atmosphere in the chamber for 10 to 120 minutes. Such hydrogenation heat treatment is described with reference to Fig. 2. Fig. 2 is a graph showing the hydrogen absorption behavior of titanium according to the hydrogenation heat treatment illustrated in Fig. 1.

As illustrated in Fig. 2, titanium absorbs hydrogen at around 420 to 510°C when the temperature is raised in a hydrogen atmosphere and is hydrogenated (Ti → TiH ₂ ). When titanium is hydrogenated, its brittleness increases and its volume expands during hydrogenation, causing it to fracture on its own. In other words, if the hydrogenation process is well utilized, titanium in a metallic state can be processed into briquettes, which requires a lot of work, without any special process addition. At this time, the process conditions are such that the hydrogenation heat treatment is performed at around 550 to 650°C, which is higher than 510°C, the temperature at which hydrogenation is completed, and the holding time at the highest temperature is within 10 to 120 minutes. Preferably, as illustrated in Fig. 2, the heating rate is 5°C/min, and the heat treatment can be performed at a temperature of 650°C in a hydrogen atmosphere in the chamber for 60 minutes. However, it is not limited to the process conditions described above, and can be determined depending on the size of the titanium scrap and the crushed size after final hydrogenation.

Figure 3 is a photograph to explain the self-crushed appearance of titanium after hydrogenation. Figure 3 (a) is a photograph showing the state of titanium before hydrogenation, and Figure 3 (b) is a photograph showing the state of crushed titanium after hydrogenation.

The hydrogenation heat treatment of titanium as described above affects not only physical crushing but also oxygen refining inside the titanium. When the hydrogenated titanium scrap is placed in a vacuum atmosphere, hydrogen escapes. Thermodynamically, hydrogen molecules (H ₂ ) in the external environment cannot remove oxygen from oxidized titanium (TiO ₂ ). That is, hydrogen can thermodynamically reduce oxidized iron (Fe ₂ O ₃ ), but cannot reduce oxidized titanium. However, it was confirmed thermodynamically that hydrogen atoms (H) dissociated from hydrogen molecules can remove oxygen from oxidized titanium, as shown in Fig. 4. Fig. 4 is a graph explaining the reducibility of titanium according to the hydrogen state.

Next, in the step S30, the hydrogenated titanium is dehydrogenated to remove oxygen present inside the titanium (S40). The step S40 is described with reference to FIG. 5. FIG. 5 is a drawing for explaining the behavior of hydrogen atoms and molecules during dehydrogenation. The above-described steps S30 and S40 can be performed sequentially.

In the hydrogenation of titanium in the step S30 described above, as shown in FIG. 5, hydrogen molecules (H ₂ ) are adsorbed from the outside onto the titanium surface, then dissociate into hydrogen atoms (H) and enter the titanium. On the contrary, when hydrogen comes out of titanium in the dehydrogenation such as in the step S40, the hydrogen atoms inside the titanium diffuse to the surface, become molecules on the surface, and then come out. In other words, the oxygen existing inside can be removed due to the hydrogen atoms inside during the dehydrogenation. At this time, the temperature at which hydrogen and oxygen actually react to generate the reactant water (H ₂ O) was approximately 600°C, as can be seen in FIG. 6. In other words, when hydrogen is removed from the titanium hydrogenated according to the step S30 at a temperature of 600 to 650°C under a vacuum atmosphere of the chamber during the dehydrogenation, the oxygen existing inside can be removed. Figure 6 is a graph for confirming the oxygen removal behavior during dehydrogenation using TG-MS (Thermo Gravimetry-Mass Spectrometer) measurement.

In the above step S40, since oxygen is not completely removed at once during dehydrogenation but progresses gradually as dehydrogenation proceeds, it is necessary to repeatedly perform hydrogenation-dehydrogenation as necessary. At this time, the temperature condition for performing the hydrogenation and dehydrogenation processes without temperature change is appropriately 600 to 650°C.

Accordingly, the present invention manufactures titanium scrap in the form of briquettes through hydrogenation, then, when melting through a vacuum melting method, charges the hydrogenated titanium scrap briquettes, and, before melting, removes oxygen through dehydrogenation at a temperature of 600 to 650° C. in a vacuum atmosphere, thereby producing a high-purity recycled titanium ingot or titanium powder from the titanium scrap through the final melting and production of the ingot.

As described above, the Ti briquette for melting prepared by the step S40 can be manufactured from a titanium ingot or titanium powder. In addition, it can be simultaneously implemented in a briquette shape together with oxygen refining for recycling titanium scrap.

The production of the above-described titanium ingot or titanium powder is described with reference to FIGS. 7 and 8.

FIG. 7 is a drawing showing an example of a manufacturing device for manufacturing a titanium ingot by applying a Ti briquette manufactured according to the present invention, and FIG. 8 is a drawing showing an example of a manufacturing device for manufacturing a titanium powder by applying a Ti briquette manufactured according to the present invention. In addition, since the configuration shown in FIGS. 7 and 8 is a configuration of a manufacturing device applied for and registered by the inventor of the present invention and is disclosed in the above-mentioned patent document 3, only the features of the configuration will be roughly described.

The Ti briquettes manufactured according to the present invention can be supplied into the interior of the crucible part (10) through the raw material supply part (70) illustrated in FIG. 7. The crucible part (10) is accommodated in the main chamber (20), and the manufacturing device is configured to include a plasma heating part (40) that generates high-temperature hydrogen plasma. The crucible part (10) can be equipped with a crucible (11) made of a conventional copper material to melt the Ti briquettes filled therein to form a molten metal (13). A tubular opening is formed on the lower surface of the crucible part (10) so that the molten metal (13) can be withdrawn to the outside, and a high-purity titanium seed ingot (12) is placed in this opening to close the opening.

The plasma heating unit (40) is installed on the upper part of the crucible unit (10) to generate high-temperature hydrogen plasma to melt the titanium raw material and form the molten metal (13), and an inert gas and hydrogen gas are supplied to the plasma heating unit (40) through gas supply units (50, 60). The first gas supply unit (50) includes an argon storage tank (51), a first gas supply pipe (52) connecting the argon storage tank (51) and the plasma heating unit, and a first supply control valve (53) installed in the middle of the first gas supply pipe (52), and the second gas supply unit (60) includes a hydrogen storage tank (61), a second gas supply pipe (62) connecting the hydrogen storage tank (61) and the plasma heating unit, and a second supply control valve (63) installed in the middle of the second gas supply pipe (62).

In addition, a hydrogen sensor unit (14) for detecting hydrogen concentration and a steam sensor unit (15) for detecting steam concentration are provided inside the main chamber (20), and a raw material supply unit (70) is provided to supply Ti briquettes (72) according to the present invention into the interior of the crucible (11) through a raw material supply pipe (71) connected to one side of the main chamber (20), and is configured to include an exhaust device unit (80) for exhausting the interior of the main chamber (20). The exhaust device unit (80) is configured to include an exhaust pump (81) configured as a rotary pump or the like, an exhaust pipe (82) connecting the exhaust pump (81) and the interior of the main chamber (20), and an exhaust control valve (83) installed in the middle of the exhaust pipe (82).

The high-purity titanium material manufacturing device illustrated in Fig. 8 includes an ingot puller (91) of a molten metal withdrawal section, and according to the operation of the ingot puller (91), the molten metal (13) can be withdrawn from the lower part of the crucible section (10) to manufacture a high-purity titanium ingot (12').

Next, referring to FIG. 8, a description will be given of a configuration for manufacturing titanium powder by applying Ti briquettes manufactured according to the present invention. In addition, since the configuration illustrated in FIG. 8 differs from the configuration illustrated in FIG. 7 only in the configuration of the crucible portion (10) and the configuration of the molten metal withdrawal portion (190), only a description of these will be given, and the same drawing reference numerals will be given to the same configuration as that illustrated in FIG. 7, and duplicate descriptions will be omitted.

In the configuration for manufacturing titanium powder illustrated in FIG. 8, a nozzle (16) for discharging molten metal (13) is formed on the lower surface of a crucible part (10), a hollow portion (17) is formed that surrounds the outer surface of the nozzle (16) and is opened toward the outlet of the nozzle (16), and an induction heating part (30) for heating the interior of the crucible part (10) by an induction heating method is provided on the outer surface of the crucible part (10). The induction heating part (30) may include an induction coil installed on the outer wall of the crucible part (10) and a power supply part for applying high-frequency AC power to the induction coil.

The above induction heating unit (30) is operated for the purpose of controlling the initial melting of the seed ingot (12) or the discharge temperature of the molten metal (13), and the molten metal withdrawal unit (190) may include a gas injection device that injects high-pressure gas into the hollow portion (17) and a powder collection device (194) that collects spherical titanium powder (13') that is drawn to the lower portion of the crucible portion (10) by the gas injection device.

The above gas injection device includes a gas storage tank (191) filled with high-pressure gas, a connecting pipe (192) connecting the gas storage tank (191) and the hollow portion (17), and an injection control valve (193) installed in the middle of the connecting pipe (192). When the temperature of the molten metal (13) is higher than the melting point of titanium, the control unit operates the gas injection device so that the molten metal (13) can be extracted in the form of a spherical powder as illustrated in FIG. 8 by the injection force of the high-pressure gas.

As described above, a high-purity titanium ingot or titanium powder can be manufactured by applying the Ti briquette for melting manufactured according to the present invention.

Although the invention made by the present inventor has been specifically described according to the above embodiments, the present invention is not limited to the above embodiments and can be modified in various ways without departing from the spirit thereof.

By using the method for manufacturing a Ti briquette for melting for recycling Ti scrap according to the present invention, it is possible to simultaneously implement oxygen refining for recycling titanium scrap into a briquette shape.

Claims (7)

A method for manufacturing Ti briquettes for melting to recycle titanium (Ti) scrap,
(a) a step for preparing titanium scrap as a by-product generated after titanium processing;
(b) a step of washing the titanium scrap prepared in step (a);
(c) a step of hydrogenating and heat treating the titanium scrap washed in the above step (b);
(d) a step of dehydrogenating the hydrogenated titanium in the step (c) to remove oxygen present inside the titanium;
A method for manufacturing Ti briquettes for melting, characterized in that the above steps (c) and (d) are performed sequentially. In paragraph 1,
A method for manufacturing Ti briquettes for melting, characterized in that the heat treatment in the above step (c) is performed at a temperature of 550 to 650°C for 10 to 120 minutes under a hydrogen atmosphere in a chamber. In paragraph 1,
A method for manufacturing Ti briquettes for melting, characterized in that the dehydrogenation in the above step (d) is performed at a temperature of 600 to 650°C under a vacuum atmosphere in a chamber. In paragraph 2,
A method for manufacturing Ti briquettes for melting, characterized in that the heat treatment in the above step (c) is performed at a temperature of 650°C for 60 minutes under a hydrogen atmosphere in a chamber. In paragraph 3,
A method for producing Ti briquettes for melting, characterized in that in the above step (d), the removal of oxygen is performed by hydrogen atoms (H) dissociated from hydrogen molecules from oxidized titanium. A titanium ingot characterized in that it is manufactured by melting a briquette manufactured by the method for manufacturing a Ti briquette for melting according to any one of claims 1 to 5. A titanium powder characterized in that it is manufactured by melting a briquette manufactured by the method for manufacturing a Ti briquette for melting according to any one of claims 1 to 5.