KR101101755B1 - Method for recycling waste cemented carbide sludge - Google Patents

Abstract

The present invention, the waste cemented carbide sludge containing tungsten carbide and cobalt as a main component in hexane or ethanol and stirred to remove the cutting oil components contained in the waste cemented carbide sludge, impurities contained in the waste cemented carbide sludge from which the cutting oil components are removed Primary acid treatment is performed to dissolve and remove tungsten carbide powder or tungsten oxide powder, and the tungsten carbide powder or tungsten oxide powder agglomerated by the remaining impurity components is pulverized to increase the surface area and then pulverized to increase the surface area. The present invention relates to a method of regenerating waste cemented carbide sludge which is made by tungsten carbide powder or tungsten oxide powder by secondary acid treatment to dissolve and remove impurities present or separated by the grinding process. According to the regeneration method of the cemented carbide according to the present invention, since no oxidation process or reduction process is required, impurities such as particle growth inhibitors are less introduced, resulting in high purity, low energy consumption, and no grain growth during the process. Obtainable and the process is relatively simple and reproducible.

Waste cemented carbide sludge, scrap, recycle, tungsten carbide, tungsten oxide

Description

Method for recycling waste cemented carbide sludge

The present invention relates to a method for regenerating waste cemented carbide sludge mainly composed of tungsten carbide (WC) and cobalt (Co), and more particularly, cemented carbide waste scrap sludge composed mainly of tungsten carbide (WC) and cobalt (Co). From a high purity tungsten carbide (WC) and tungsten oxide.

As cutting tools requiring high hardness, alloys of carbon steel, tungsten steel, and a mixture of chromium and cobalt have been used since early. In 1923, German chemist Schrotter discovered a method of mixing and sintering tungsten carbide powder and cobalt powder. In 1927, German Krupp developed an ultrahard alloy mainly made of tungsten carbide by this method.

Cemented carbide is an alloying material made of high melting point and high strength material mainly composed of expensive tungsten carbide (WC) and cobalt (Co) due to its small reserves.

Such cemented carbide is currently composed of three series alloys of WC-Co, WC-TiC-Co, and WC-TiC-TaC-Co, which are the mainstream of cemented carbide tools, and tungsten carbide (WC) for the production of cemented carbide with high toughness and high strength. The research to refine the particle size has been extensively performed. In order to suppress grain growth of tungsten carbide (WC), chromium (Cr) and vanadium (V) are used as particle growth inhibitors.

As such, although tungsten carbide is widely used as a main raw material for cemented carbide, it is very expensive due to its low resource reserves.

However, since the cemented carbide is a high melting point and a high strength sintered body, it is known that it is difficult to recycle even though it is an industrial waste with sufficient added value when it is recycled due to problems of regeneration, environmental problems, and economics by physical and chemical methods.

Regarding the regeneration of waste cemented carbide, Korean Patent No. 10-0537430 proposes a method for preparing a metal carbide carbide cemented powder using waste cemented scrap. Patent No. 10-0537430 discloses the steps of oxidizing the waste cemented carbide scrap in the air, pulverizing and oxidizing the oxidized waste cemented carbide scrap, and supplying a carbon source to the pulverized oxidized waste carbide scrap powder to reduce / It comprises a carbonization step, the reduction / carbonization step is a metal-carbide cemented carbide powder using waste cemented carbide scraps, characterized in that the mixed / solid carbon powder as a carbon source to reduce / carbonize in an inert atmosphere The preparation method of the present is shown.

However, since the metal-carbide cemented carbide powder has a reduction process after the oxidation process, it has impurities such as cobalt and grain growth inhibitors in the recycling process, and thus, purity is lowered, and high energy is required in this process. have.

In addition, the Republic of Korea Patent No. 10-0321520 is a process for mixing the content of the bar stone powder scrap with 1 equivalent of Na ₂ CO ₃ , adding a hard scrap to the mixed powder and heating to 600 ~ 800 ℃, Na after heating The process of melting a hard stone scrap comprising the steps of dissolving hard scrap by adding 0.1-1.5 equivalents of NaNO ₃ and 0.5 equivalents of NaOH, followed by promoting the reaction by adding 0.5-2.0 equivalents of NaNO ₂ . Here's how.

However, the treatment method by melting the barite-containing scrap is tungsten oxide rather than tungsten carbide because the tungsten is oxidized when Na ₂ CO ₃ is added to the barite-scrap and heated to 600-800 ° C., followed by NaNO ₃ and NaOH. (Tungsten oxide) is obtained. Therefore, this method also requires a reduction process for reducing tungsten oxide, there are limitations in obtaining high purity tungsten carbide by adding impurities in the reduction process, and there is a disadvantage in that high energy is required in the reduction process.

In addition, Korean Patent Application No. 10-2007-0059108 discloses a method for recovering high-purity tungsten powder from sludge generated during the processing of cemented carbide tools. The present invention relates to the treatment of sludge containing tungsten, and to recovering tungsten and valuable metals in the sludge with a high yield through a simple process using inorganic acids (nitric acid, hydrochloric acid, sulfuric acid). A tungsten recovery method comprising an acid treatment step of separating tungsten from other components by drying the sludge containing tungsten to obtain a dry powder to remove impurities and acidifying the powder with an inorganic acid. In this invention, nitric acid was mainly used.

According to the Republic of Korea Patent Application No. 10-2007-0059108, to obtain here is a tungsten powder, further comprising a reduction step of reducing the tungsten powder after the acid treatment, if the temperature is low in the reduction process is not completely reduced When the temperature is high, there is a problem that the particles are coarse, there is a limit in obtaining high purity tungsten by the addition of impurities in the reduction process, there is a disadvantage that high energy is required in the reduction process.

The present invention has been made to solve the above problems, the present invention does not require an oxidation process or a reduction process, so the inflow of impurities, such as particle growth inhibitors are small, high purity, low energy consumption, and grain growth during the process Not only does not occur to obtain a fine tungsten carbide or tungsten oxide powder, but also to provide a method for regenerating waste cemented carbide sludge with a relatively simple and reproducible process.

The present invention comprises the steps of (a) immersing the waste cemented carbide sludge containing tungsten carbide and cobalt in hexane or ethanol and stirring to remove the cutting oil component contained in the waste cemented carbide sludge, and (b) the cutting oil component is removed Primary acid treatment with hydrochloric acid to dissolve and remove impurities contained in the waste cemented carbide sludge, (c) washing the tungsten carbide powder obtained by the primary acid treatment with a cleaning solution, and (d) remaining impurity components. Pulverizing the cleaned tungsten carbide powder using tungsten carbide carbide balls or steel balls to increase the surface area by micronizing the tungsten carbide powder agglomerated by (e) present on the surface of the pulverized tungsten carbide powder or by crushing Secondary with hydrochloric acid to dissolve and remove impurities released from tungsten carbide It provides the step of processing and (f) 2 primary acid and then washing the treated tungsten carbide powder obtained by the reproduction method with a washing solution of the lung cemented carbide sludge, comprising the step of drying.

In the steps (b) and (e), the acid treatment is carried out at room temperature for 30 minutes to 48 hours, it is preferable to use a hydrochloric acid solution having a concentration of hydrochloric acid higher than 20%.

In the acid treatment of steps (b) and (e), the content of the waste cemented carbide sludge and hydrochloric acid is preferably in the range of 1: 1 to 10 by weight.

The grinding may be performed using a ball mill using tungsten carbide carbide balls made of the same material as tungsten carbide powder, and the rotational speed of the ball mill is set in a range of 100 to 400 rpm for 12 to 48 hours.

In addition, the present invention, (a) dipping the waste cemented carbide sludge containing tungsten carbide and cobalt as a main component in hexane or ethanol and stirring to remove the cutting oil components contained in the waste cemented carbide sludge, and (b) the cutting oil component Primary acid treatment with aqua regia or nitric acid, which is a mixture of nitric acid and hydrochloric acid, to dissolve and remove impurities contained in the removed waste cemented carbide sludge; and (c) tungsten oxide powder obtained by primary acid treatment as a washing solution. (D) pulverizing the cleaned tungsten oxide powder using tungsten carbide carbide balls or steel balls to increase the surface area by micronizing the tungsten oxide powder agglomerated by the remaining impurity components; and (e) grinding Present on the surface of tungsten oxide powder or released from tungsten oxide by a grinding process Secondary acid treatment with aqua regia or nitric acid, which is a solution of nitric acid and hydrochloric acid in order to dissolve and remove impurities, and (f) washing the tungsten oxide powder obtained by the secondary acid treatment with a washing solution and then drying. Provided is a method for regeneration of waste cemented carbide sludge.

In the steps (b) and (e), the acid treatment is carried out for 30 minutes to 48 hours at a temperature of 60 to 100 ℃, the aqua regia is mixed with nitric acid and hydrochloric acid in a volume ratio of 1-3: 1 It is preferable to use a solution.

In the acid treatment of steps (b) and (e), the content of the waste cemented carbide sludge and aqua regia or nitric acid is preferably in a weight ratio of 1: 1 to 10.

The grinding may be performed using a ball mill using tungsten carbide carbide balls made of the same material as tungsten carbide powder, and the rotational speed of the ball mill is set in a range of 100 to 400 rpm for 12 to 48 hours.

According to the present invention, tungsten carbide (WC) having a purity of 99% or more can be recovered from waste cemented carbide sludge containing tungsten carbide and cobalt as a main component using a simple process.

In addition, tungsten oxide (WO ₃ ) having a purity of 99% or more can be produced from waste cemented carbide sludge mainly composed of tungsten carbide and cobalt using a simple process.

In the conventional case, a complex process of reducing after acid treatment is required. However, in the present invention, high purity tungsten carbide (WC) or tungsten oxide (WO ₃ ) may be obtained using only an acid treatment process without the need for a reduction process.

In addition, since a chemical process rather than an oxidation process is used, particle growth does not occur, thereby preparing fine tungsten carbide (WC) or tungsten oxide (WO ₃ ).

Fine milling of tungsten carbide (WC) and tungsten oxide (WO ₃ ) through a ball milling process using cemented carbide or steel balls to increase the surface area, and then purifying the purity of tungsten carbide and tungsten oxide by removing impurities through a secondary acid treatment process Can be increased to 99% or more.

According to the present invention, expensive tungsten carbide, the main raw material for cemented carbide tools and electronic components, is in short supply due to a surge in global demand, but it is economically advantageous because it can be recycled and reused.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the following embodiments are provided to those skilled in the art to fully understand the present invention, and may be modified in various forms, and the scope of the present invention is limited to the embodiments described below. It doesn't happen. Like numbers refer to like elements in the figures.

Prepare waste cemented carbide sludge. The waste cemented carbide is a waste scrap of a cemented carbide tool containing tungsten carbide (WC) and cobalt (Co) as main components. 1 is an X-ray diffraction (XRD) photograph of waste cemented carbide sludge. It can be seen that small sized diffraction peaks appear as shown in FIG. 1, which is due to impurities such as cobalt (Co), iron (Fe), and the like. In Figure 1 'W' represents the diffraction peak of tungsten carbide (WC).

Table 1 below shows the results of Inductively Coupled Plasma (ICP) analysis for waste cemented carbide sludge.

Component content(%) Al 0.32 Ni 2.12 C 12.09 Co 7.13 W 74.87 Fe 1.12 Si 1.27 Cr 0.45 V 0.63

Waste cemented carbide sludge is an industrial waste that is already used and disposed of, and contains cutting oil (oil) components used for processing metals and the like. This coolant component surrounds the waste cemented carbide sludge particles. If not removed, the coolant component interferes with dissolution of impurities due to acid treatment in the subsequent acid treatment process, and therefore, high purity tungsten carbide (WC) and tungsten oxide ( There may be limitations in obtaining WO ₃ ). Therefore, in order to remove the cutting oil component present in the waste cemented carbide sludge, the waste cemented carbide sludge is immersed in hexane (Hexane) or ethanol and stirred for a predetermined time. Since the cutting oil component is dissolved in hexane or ethanol, the cutting oil component can be removed from the waste cemented carbide sludge by filtering the waste cemented carbide sludge. Removal of oil components using hexane (Hexane) or ethanol can be carried out at a temperature of about 10 ~ 40 ℃.

Hereinafter, acid-treated waste cemented carbide sludge from which the coolant component is removed is obtained by hydrochloric acid (HCl) to obtain tungsten carbide (WC) powder of high purity, or nitric acid and hydrochloric acid are mixed at a predetermined ratio. The process of acid treatment with a solution (aqua regia) to obtain a high purity tungsten oxide (WO ₃ ) powder will be described.

First, a process of obtaining tungsten carbide (WC) powder will be described.

Waste cemented carbide sludge from which coolant is removed is acid treated with hydrochloric acid (HCl) solution. Acid treatment with hydrochloric acid (HCl) solution dissolves cobalt (Co) in waste cemented carbide sludge, and trace amounts of V, Cr, Ti, Fe, etc. contained in waste cemented carbide sludge are also dissolved in hydrochloric acid (HCl). Will be dissolved in and removed. The acid treatment process using the hydrochloric acid (HCl) solution is preferably carried out for 30 minutes to 48 hours at room temperature (for example 15 to 25 ℃). As the hydrochloric acid solution, it is preferable to use a solution having a concentration of hydrochloric acid (HCl) higher than 20%. This is because the type and amount of impurities removed may vary depending on the concentration of hydrochloric acid. For example, when the concentration of hydrochloric acid is high, cobalt (Co) component is dissolved, but when the concentration of hydrochloric acid is low, cobalt (Co) component is not dissolved and only impurities such as iron (Fe) may be dissolved. Waste cemented carbide sludge and hydrochloric acid are preferably 1: 1 to 10 by weight. If the amount of hydrochloric acid is too small, impurities such as cobalt (Co) and iron (Fe) cannot be sufficiently removed, and if the amount of hydrochloric acid is too high, it may be difficult to expect further impurities removal effects and waste of raw materials. As not economical.

After the acid treatment step, a tungsten carbide (WC) powder is obtained by washing several times (eg, three times) with a washing solution such as ethanol and then drying. The tungsten carbide (WC) powder thus obtained may have a purity of 95% or more.

However, since trace impurities such as cobalt (Co) still remain in the tungsten carbide (WC) powder thus obtained, such residual impurities may act as a binder to aggregate the tungsten carbide (WC) powder. Therefore, in order to further micronize the obtained tungsten carbide (WC) powder, a grinding process can be used. However, the aggregated tungsten carbide (WC) powder is also a high-strength material, so it is difficult to atomize it by a simple grinding method to obtain it in powder form.

Tungsten carbide (WC) powder is charged to a ball milling machine (ball milling machine) to micronize and wet mixed with a solvent such as ethanol. The tungsten carbide (WC) powder is mechanically ground by rotating at a constant speed using a ball mill. The ball used for ball milling uses carbide balls or steel balls made of tungsten carbide, the same material as tungsten carbide powder, to suppress the generation of impurities. The balls may be of the same size or may have two or more sizes. Can also be used together. Grind to the size of the target particle by adjusting the size of the ball, milling time, rotation speed per minute of the ball mill. For example, in consideration of the particle size, the size of the ball can be set in the range of about 1 mm to 50 mm, and the rotational speed of the ball mill can be set in the range of about 100 to 400 rpm. Ball milling is performed for 12 to 48 hours in consideration of the target particle size and the like. Impurity components such as cobalt (Co), which bind tungsten carbide (WC) powder by ball milling, are released away from the tungsten carbide (WC) particles, thus tungsten carbide (WC) is crushed into finely sized particles and uniform It has a particle size distribution.

A secondary acid treatment process is performed on tungsten carbide (WC) powder that has been micronized through the grinding process to increase its surface area. Hereinafter, a process of obtaining a high purity tungsten carbide (WC) powder by secondary acid treatment of the ground tungsten carbide (WC) powder with hydrochloric acid (HCl) will be described.

Tungsten carbide (WC) powder is acid treated with hydrochloric acid (HCl) solution. By secondary acid treatment with hydrochloric acid (HCl) solution, cobalt (Co) present on the surface of tungsten carbide (WC) or released from the tungsten carbide (WC) by the grinding process is dissolved. In addition, impurities such as V, Cr, Ti, and Fe contained in a small amount in tungsten carbide (WC) powder may be removed by a secondary acid treatment process using the hydrochloric acid (HCl) solution. Since the surface area of the tungsten carbide (WC) powder is large by the grinding process, hydrochloric acid may act on the powder particles more effectively than the primary acid treatment. The secondary acid treatment process using the hydrochloric acid (HCl) solution is preferably carried out for 30 minutes to 48 hours at room temperature (for example 15 to 25 ℃).

After the secondary acid treatment process, a tungsten carbide (WC) powder is obtained by washing several times (eg, three times) with a cleaning solution such as ethanol and then drying.

The tungsten carbide (WC) powder thus obtained may have a purity of 99% or more, and the powder particle size may be about 0.5 to 3 μm.

Next, a process of obtaining tungsten oxide (WO ₃ ) powder will be described.

Waste cemented carbide sludge from which coolant is removed is acid treated with aqua regia or nitric acid. The aqua regia is a solution in which nitric acid (HNO ₃ ) and hydrochloric acid (HCl) are mixed at a predetermined ratio (eg, 1 to 3: 1) by volume ratio. Acid treatment with aqua regia or nitric acid (HNO ₃ ) dissolves cobalt (Co) contained in waste cemented carbide sludge, and trace amounts of V, Cr, Ti, Fe, etc. contained in waste cemented carbide sludge are also found in aqua regia or It is dissolved in nitric acid and removed, and the bonding of tungsten (W) and carbide (C) is broken so that tungsten (W) is oxidized. The acid treatment step using aqua regia or nitric acid is preferably carried out for 30 minutes to 48 hours at a temperature of 60 ~ 100 ℃. Acid treatment process using aqua regia or nitric acid is preferably carried out at a temperature of 60 ~ 100 ℃, when the temperature is less than the above range, the oxidation rate of tungsten carbide (WC) is slow.

The waste cemented carbide sludge and the acid treatment solution (aqua regia or nitric acid) are preferably 1: 1 to 10 by weight. If the content of aqua regia or nitric acid is too small, impurities such as cobalt (Co) and iron (Fe) may not be sufficiently removed, and there may be a limit to oxidizing tungsten by breaking tungsten and carbide (C) bonds. Alternatively, if the content of nitric acid is too high, it may be difficult to expect further impurities removal effect and oxidation effect of tungsten and it is not economical as waste of raw materials.

After the acid treatment step, a tungsten oxide (WO ₃ ) powder is obtained by washing several times (eg, three times) with a washing solution such as ethanol and water, followed by drying. The drying is preferably carried out at a temperature of about 50 ~ 200 ℃. The tungsten oxide (WO ₃ ) powder after drying is yellow or green, and the tungsten oxide (WO ₃ ) powder thus obtained may have a purity of 95% or more.

However, since a small amount of impurities such as cobalt (Co) still remain in the tungsten oxide (WO ₃ ) powder thus obtained, the remaining impurities may act as a binder to aggregate the tungsten oxide (WO ₃ ) powder. Therefore, in order to further micronize the obtained tungsten oxide (WO ₃ ) powder, a grinding process can be used. However, the aggregated tungsten oxide (WO ₃ ) powder is also a high-strength material, so it is difficult to obtain it in powder form by atomizing by a simple grinding method. Therefore, it is preferable to use the following grinding process.

To tungsten tungsten oxide (WO ₃ ) powder is charged into a ball milling machine (ball milling machine) and wet mixed with a solvent such as water and ethanol. The tungsten oxide (WO ₃ ) powder is mechanically ground by rotating at a constant speed using a ball mill. Balls used in ball milling use carbide balls or steel balls made of tungsten carbide to suppress the generation of impurities, and the balls may be all the same size or may have balls of two or more sizes together. Grind to the size of the target particle by adjusting the size of the ball, milling time, rotation speed per minute of the ball mill. For example, in consideration of the particle size, the size of the ball can be set in the range of about 1 mm to 50 mm, and the rotational speed of the ball mill can be set in the range of about 100 to 400 rpm. Ball milling is performed for 12 to 48 hours in consideration of the target particle size and the like. Impurity components such as cobalt (Co), which bind tungsten oxide (WO ₃ ) powder by ball milling, are released away from the tungsten oxide (WO ₃ ) particles, thus tungsten oxide (WO ₃ ) is crushed into fine-sized particles This results in a uniform particle size distribution.

The secondary acid treatment is performed on the tungsten oxide (WO ₃ ) powder which is micronized through the crushing process to increase the surface area. Hereinafter, a process of obtaining a high purity tungsten oxide (WO ₃ ) powder by secondary acid treatment of the ground tungsten oxide (WO ₃ ) powder with aqua regia or nitric acid will be described.

The tungsten oxide (WO ₃ ) powder is subjected to secondary acid treatment with aqua regia or nitric acid in which nitric acid (HNO ₃ ) and hydrochloric acid (HCl) are mixed in a proportion (eg, 1 to 3: 1 by volume). Cobalt (Co) present on the surface of tungsten oxide (WO ₃ ) or separated by tungsten oxide (WO ₃ ) by secondary acid treatment with aqua regia or nitric acid is dissolved. In addition, impurities such as V, Cr, Ti, and Fe contained in a small amount in the tungsten oxide (WO ₃ ) powder may be removed by the secondary acid treatment process using aqua regia or nitric acid. Since the surface area of the tungsten oxide (WO ₃ ) powder is wide by the grinding process, aqua regia or nitric acid may act on the powder particles more effectively than the primary acid treatment. The secondary acid treatment step using aqua regia or nitric acid is preferably carried out for 30 minutes to 48 hours at a temperature of 60 ~ 100 ℃.

After secondary acid treatment with aqua regia or nitric acid, tungsten oxide (WO ₃ ) powders are obtained by washing several times (eg, three times) with a cleaning solution such as ethanol and water, followed by drying.

The tungsten oxide (WO ₃ ) powder thus obtained may have a purity of 99% or more, and the powder particle size may be about 0.5 to 3 μm.

In the following, the invention is described in more detail with reference to the following examples, which do not limit the invention.

≪ Example 1 >

A waste cemented carbide sludge composed of waste scrap of a cemented carbide tool composed mainly of tungsten carbide (WC) and cobalt (Co) was prepared.

In order to remove the cutting oil (oil) component in the waste cemented carbide sludge, the waste cemented carbide sludge was immersed in a hexane solution and stirred for 2 hours. At this time, the removal of the oil component using hexane (Hexane) was performed at a temperature of about 25 ℃. As the hexane, normal hexane (n-hexane) having a concentration of 95% was used.

The waste cemented carbide sludge from which the coolant was removed was subjected to primary acid treatment with hydrochloric acid (HCl) solution. The first acid treatment process using the hydrochloric acid (HCl) solution was carried out at room temperature for 24 hours. As the hydrochloric acid solution, a solution having a concentration of hydrochloric acid (HCl) of 35.5% was used. When acid treated with hydrochloric acid (HCl) solution, it was found that cobalt (Co) was extracted by melting dark blue.

After the first acid treatment step washed three times with ethanol and dried to obtain a tungsten carbide (WC) powder. The drying was carried out in a constant temperature dryer at 80 ℃ for 1 hour.

FIG. 2 is a photograph of the obtained tungsten carbide (WC) powder at 1000 times using a scanning electron microscope (SEM), and FIG. 3 is a scanning electron microscope (SEM) of the thus obtained tungsten carbide (WC) powder. The photograph was observed at 5000 times using. As shown in FIGS. 2 and 3, the tungsten carbide (WC) powder can be seen to be agglomerated due to impurities such as cobalt (Co) in which small amounts of tungsten carbide (WC) particles remain.

Since trace impurities such as cobalt (Co) still remain in the tungsten carbide (WC) powder thus obtained, such residual impurities act as a binder to aggregate the tungsten carbide (WC) powder. Therefore, a ball mill grinding process was performed to further micronize the obtained tungsten carbide (WC) powder. However, the aggregated tungsten carbide (WC) powder is also a high-strength material, so it is difficult to obtain it in powder form by atomizing by a simple grinding method.

The tungsten carbide (WC) powder was charged to a ball milling machine in order to micronize and wet mixed with ethanol. The tungsten carbide (WC) powder was mechanically ground by rotating the ball mill at a constant speed. The ball used for ball milling used carbide balls made of tungsten carbide (WC), the ball size was 10 mm, 20 mm, 30 mm, the rotation speed of the ball mill was set to about 300rpm, ball milling 24 hours Was carried out.

The secondary acid treatment process was performed with hydrochloric acid (HCl) solution on the finely divided tungsten carbide (WC) powder through the grinding process. The secondary acid treatment process using the hydrochloric acid (HCl) solution was carried out at room temperature. As the hydrochloric acid solution, a solution having a concentration of hydrochloric acid (HCl) of 35.5% was used. When acid treated with hydrochloric acid (HCl) solution, it was found that cobalt (Co) was extracted by melting dark blue.

After the second acid treatment step washed three times with ethanol and dried to obtain a tungsten carbide (WC) powder. The drying was carried out in a constant temperature dryer at 80 ℃ for 1 hour.

4 is a photograph of a tungsten carbide (WC) powder obtained after the secondary acid treatment step 1000 times using a scanning electron microscope (SEM), Figure 5 is a tungsten carbide (WC) powder obtained after the secondary acid treatment step The photograph was observed 5000 times using the scanning electron microscope (SEM).

It can be seen that the tungsten carbide (WC) powders shown in FIGS. 4 and 5 are fine and uniform in particle size as compared to the tungsten carbide (WC) powders shown in FIGS. 2 and 3. The tungsten carbide (WC) powder thus obtained had a purity of tungsten carbide (WC) of about 99.45% and a powder particle size of about 0.5 to 3 µm.

The tungsten carbide (WC) powder obtained through the secondary acid treatment process was about 99.45% pure. Table 2 below shows the results of Inductively Coupled Plasma (ICP) analysis on the tungsten carbide (WC) powder obtained through the secondary acid treatment process.

Component content(%) Cr 0.13 Co 0.42 W 91.47 C 7.98

Figure 6 is a photograph showing the X-ray diffraction (XRD) pattern of the tungsten carbide (WC) powder obtained after the secondary acid treatment process. In the XRD pattern of the tungsten carbide (WC) powder shown in FIG. 6, it can be seen that little peaks due to the impurities shown in FIG. In the final tungsten carbide (WC) powder, it was found that impurities such as cobalt (Co), iron (Fe), nickel (Ni), chromium (Cr), vanadium (V) and silicon (Si) were almost completely removed. Can be.

<Example 2>

A waste cemented carbide sludge composed of waste scrap of a cemented carbide tool composed mainly of tungsten carbide (WC) and cobalt (Co) was prepared.

In order to remove the cutting oil (oil) component in the waste cemented carbide sludge, the waste cemented carbide sludge was immersed in a hexane solution and stirred for 2 hours. At this time, the removal of the oil component using hexane (Hexane) was performed at a temperature of about 25 ℃.

Waste cemented carbide sludge from which coolant was removed was acid treated with aqua regia. The aqua regia is a solution in which nitric acid (HNO ₃ ) and hydrochloric acid (HCl) are mixed at a volume ratio of 1: 1, and the acid treatment process using the aqua regia is performed at a temperature of 80 ° C. for 24 hours. Waste cemented carbide sludge and aqua regia were about 1: 2 by weight. When acid treated with aqua regia, cobalt (Co) was extracted as the dark blue melted.

After the first acid treatment step washed three times with ethanol and dried to obtain a tungsten oxide (WO ₃ ) powder. The drying was carried out in a constant temperature dryer at 80 ℃ for 1 hour. Thus obtained tungsten oxide (WO ₃ ) powder was yellow or green, the purity was about 95%.

7 is a photograph of the obtained tungsten oxide (WO ₃ ) powder 1000 times using a scanning electron microscope (SEM), Figure 8 is a tungsten oxide (WO ₃ ) powder thus obtained using a scanning electron microscope (SEM) The photograph was observed 5000 times. As shown in FIGS. 7 and 8, the tungsten oxide (WO ₃ ) powder can be seen to be agglomerated due to impurities such as cobalt (Co) remaining in a small amount.

Since a small amount of impurities such as cobalt (Co) still remain in the tungsten oxide (WO ₃ ) powder thus obtained, such residual impurities act as a binder to aggregate the tungsten oxide (WO ₃ ) powder. Therefore, a ball mill grinding process was performed to further micronize the obtained tungsten oxide (WO ₃ ) powder. However, the aggregated tungsten oxide (WO ₃ ) powder is also a high-strength material, so it is difficult to obtain it in powder form by atomizing by a simple grinding method.

Tungsten oxide (WO ₃ ) powder was charged to a ball milling machine (ball milling machine) to be micronized and wet mixed with ethanol. The tungsten oxide (WO ₃ ) powder was mechanically ground by rotating the ball mill at a constant speed. The ball used for ball milling used carbide balls made of tungsten carbide (WC), the ball size was 10 mm, 20 mm, 30 mm, the rotation speed of the ball mill was set to about 300rpm, ball milling 24 hours Was carried out.

The tungsten oxide (WO ₃ ) powder micronized through the grinding process was subjected to a second acid treatment process with aqua regia. The aqua regia is a solution in which nitric acid (HNO ₃ ) and hydrochloric acid (HCl) are mixed at a volume ratio of 1: 1, and the acid treatment process using the aqua regia is performed at a temperature of 80 ° C. for 24 hours. Waste cemented carbide sludge and aqua regia were about 1: 2 by weight. When acid treated with aqua regia, cobalt (Co) was extracted as the dark blue melted.

After the second acid treatment step washed three times with ethanol and dried to obtain a tungsten oxide (WO ₃ ) powder. The drying was carried out in a constant temperature dryer at 80 ℃ for 1 hour.

9 is a photograph of a tungsten oxide (WO ₃ ) powder obtained after the secondary acid treatment step at 1000 times using a scanning electron microscope (SEM), and FIG. 10 is a tungsten oxide (WO ₃ ) obtained after the secondary acid treatment step. The powder was observed 5000 times using a scanning electron microscope (SEM).

It can be seen that the tungsten oxide (WO ₃ ) powder shown in FIGS. 9 and 10 is fine and the particle size is uniform compared to the tungsten oxide (WO ₃ ) powder shown in FIGS. 7 and 8. The tungsten oxide (WO ₃ ) powder thus obtained had a purity of about 99.08% and a powder particle size of about 0.5 to 3 μm.

The tungsten oxide (WO ₃ ) powder obtained through the secondary acid treatment process was about 99.08% pure. Table 3 below shows the results of Inductively Coupled Plasma (ICP) analysis on the tungsten oxide (WO ₃ ) powder obtained through the secondary acid treatment process.

Component content(%) SiO ₂ 0.67 V ₂ O ₅ 0.25 WO ₃ 99.08

11 is a photograph showing an X-ray diffraction (XRD) pattern of the tungsten oxide (WO ₃ ) powder obtained after the secondary acid treatment process. In the XRD pattern of the tungsten oxide (WO ₃ ) powder shown in FIG. 11, it could be confirmed that little peaks due to the impurities shown in FIG. 1 did not appear. In the final tungsten oxide (WO ₃ ) powder obtained from this, impurities such as cobalt (Co), iron (Fe), nickel (Ni), chromium (Cr), vanadium (V) and silicon (Si) were almost completely removed. Able to know.

As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to the said embodiment, A various deformation | transformation by a person of ordinary skill in the art within the scope of the technical idea of this invention is carried out. This is possible.

1 is an X-ray diffraction (XRD) photograph of waste cemented carbide sludge.

FIG. 2 is a photograph of a tungsten carbide (WC) powder obtained after primary acid treatment at 1000 times using a scanning electron microscope (SEM).

3 is a photograph of a tungsten carbide (WC) powder obtained after primary acid treatment at 5000 times using a scanning electron microscope (SEM).

4 is a photograph of a tungsten carbide (WC) powder obtained after the secondary acid treatment step at 1000 times using a scanning electron microscope (SEM).

5 is a photograph of a tungsten carbide (WC) powder obtained after the secondary acid treatment step at 5000 times using a scanning electron microscope (SEM).

Figure 6 is a photograph showing the X-ray diffraction (XRD) pattern of the tungsten carbide (WC) powder obtained after the secondary acid treatment process.

FIG. 7 is a photograph of a tungsten oxide (WO ₃ ) powder obtained after a primary acid treatment step at 1000 times using a scanning electron microscope (SEM).

FIG. 8 is a photograph of a tungsten oxide (WO ₃ ) powder obtained after a primary acid treatment step at 5000 times using a scanning electron microscope (SEM).

FIG. 9 is a photograph of a tungsten oxide (WO ₃ ) powder obtained after a secondary acid treatment step at 1000 times using a scanning electron microscope (SEM).

10 is a photograph of a tungsten oxide (WO ₃ ) powder obtained after the secondary acid treatment step at 5000 times using a scanning electron microscope (SEM).

11 is a photograph showing an X-ray diffraction (XRD) pattern of the tungsten oxide (WO ₃ ) powder obtained after the secondary acid treatment process.

Claims (7)

(a) dipping the waste cemented carbide sludge containing tungsten carbide and cobalt in hexane or ethanol and stirring to remove the cutting oil component contained in the waste cemented carbide sludge; (b) primary acid treatment with hydrochloric acid to dissolve and remove impurities contained in the waste cemented carbide sludge from which the cutting oil components are removed; (c) washing the tungsten carbide powder obtained by the primary acid treatment with a cleaning liquid; (d) pulverizing the cleaned tungsten carbide powder using tungsten carbide carbide balls or steel balls to finely refine the tungsten carbide powder agglomerated by the remaining impurity components to increase the surface area; (e) secondary acid treatment with hydrochloric acid to dissolve and remove impurities present on the surface of the ground tungsten carbide powder or separated from the tungsten carbide by the milling process; And (f) A method for regenerating waste cemented carbide sludge comprising the step of washing the tungsten carbide powder obtained by the secondary acid treatment with a washing liquid and then drying. (a) dipping the waste cemented carbide sludge containing tungsten carbide and cobalt in hexane or ethanol and stirring to remove the cutting oil component contained in the waste cemented carbide sludge; (b) primary acid treatment with aqua regia or nitric acid, a solution of nitric acid and hydrochloric acid, to melt and remove impurities contained in the waste cemented carbide sludge from which the cutting oil components are removed; (c) washing the tungsten oxide powder obtained by the primary acid treatment with a cleaning liquid; (d) pulverizing the cleaned tungsten oxide powder using tungsten carbide carbide balls or steel balls to finely refine the tungsten oxide powder agglomerated by the remaining impurity components to increase the surface area; (e) secondary acid treatment with aqua regia or nitric acid, a solution in which nitric acid and hydrochloric acid are mixed to dissolve and remove impurities present on the surface of the ground tungsten oxide powder or separated from the tungsten oxide by a milling process; And (f) A method for regenerating waste cemented carbide sludge, which comprises the step of washing the tungsten oxide powder obtained by the secondary acid treatment with a washing liquid and then drying. The method of claim 1, wherein in steps (b) and (e), The acid treatment is carried out at room temperature for 30 minutes to 48 hours, and using a hydrochloric acid solution having a concentration of hydrochloric acid higher than 20%. The process according to claim 1, wherein in the acid treatment of steps (b) and (e), The waste cemented carbide sludge and the hydrochloric acid content is in the weight ratio of 1: 1 to 10 characterized in that the regeneration of the waste cemented carbide sludge. The method of claim 2, wherein in steps (b) and (e), Acid treatment is carried out for 30 minutes to 48 hours at a temperature of 60 ~ 100 ℃, the aqua regia of waste cemented carbide sludge, characterized in that using a mixture of nitric acid and hydrochloric acid in the ratio of 1 to 3: 1 by volume ratio How to play. The process according to claim 2, wherein in the acid treatment of steps (b) and (e), The waste cemented carbide sludge and the contents of aqua regia or nitric acid are in a weight ratio of 1: 1 to 10 characterized in that the regeneration of the waste cemented carbide sludge. According to claim 1 or 2, wherein the grinding is using a ball mill using a tungsten carbide carbide ball or steel ball, the rotational speed of the ball mill is set to a range of 100 to 400rpm is carried out for 12 to 48 hours. Waste cemented carbide sludge recycling method.

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