KR20100018737A - Recycling method of aluminium base scrap for piston - Google Patents

Abstract

PURPOSE: A recycling method of aluminum-based scraps for a piston is provided to manufacture second metal of high quality by recycling aluminum-based scraps. CONSTITUTION: A recycling method of aluminum-based scraps for a piston comprises the following steps of: pre-processing aluminum scrap(S10); forming molten metal by melting the aluminum-based scrap(S20); adding alloyed element into the molten metal(S30); and casting the molten metal(S40).

Description

Recycling method of aluminum scrap for pistons {RECYCLING METHOD OF ALUMINIUM BASE SCRAP FOR PISTON}

The present invention relates to a method for recycling aluminum-based scrap, and more particularly, to a method for producing high quality secondary now by recycling aluminum scrap for pistons.

In the automotive aluminum casting industry, the importance of aluminum recycling is being emphasized as resource depletion and environmental pollution become serious.

Automotive aluminum is used around 25 million tonnes worldwide, and a large amount of scrap occurs during the casting of aluminum. About one-third of the aluminum used in the automotive aluminum casting industry now uses recycled scrap that recycles these scraps.

Among these aluminum scraps, aluminum alloy scraps for pistons have been difficult to recycle to date. Therefore, the need for development of recycling technology for aluminum alloy scrap for pistons is emerging.

However, such an aluminum alloy scrap for pistons includes foreign materials such as cutting oil and water, and it is difficult to remove and separate these foreign substances contained in the aluminum scrap in a chip state, and an optimal pretreatment process for improving dissolution recovery rate. It is not secured.

In addition, a suitable alloy additive control and molten metal treatment process for producing high-quality Al piston aluminum-based now is not established.

In addition, it has not been established that the melting furnace and continuous casting process are established for reflection production for high quality Al pistons.

The present invention is to solve the above problems, the present invention is a pre-treatment process, alloy additive component control process, molten metal treatment process, reflection furnace melting process and continuous casting process to efficiently recycle the aluminum alloy scrap for piston The purpose is to provide.

Recycling method of aluminum-based scrap according to an embodiment of the present invention to achieve the above object is the step of drying the aluminum-based scrap in a drying furnace of the internal temperature 300 ~ 420 ℃, to melt the dried aluminum-based scrap to form a molten metal And casting the molten metal into a mold.

The method may further include removing foreign substances including iron from the aluminum-based scrap.

Removing the foreign matter may include removing the foreign matter using the bulk filter device, and removing the foreign matter using magnetic force.

Drying the aluminum-based scrap may be performed for 3 to 5 minutes.

In the recycling method of aluminum scrap according to another embodiment of the present invention, the forming of the molten metal may include charging the aluminum-based scrap dried in the furnace at a temperature of 690 to 710 ° C, and adding an alloying element to the molten metal at a temperature of 720 to 730 ° C. Adding, and removing slag at a temperature of 690-710 ° C.

The recycling method of aluminum scrap according to another embodiment of the present invention may further include adding an additive for refining the tissue to the molten metal.

The additive may comprise 0.4-0.6 wt% Ti, 0.4-0.6 wt% Zr, 40-50 ppm AlCuP, or 0.02-0.06 wt% Sr.

The recycling method of the aluminum-based scrap may further include removing impurities using a porous filter from the melted molten metal. In this case, the porous filter may be a ceramic filter.

Maintaining the temperature of the mold at 200 ~ 300 ℃ in the casting step can be continuously cast. The drying furnace may be a rotary kiln.

According to the recycling method of aluminum-based scrap according to the present invention, it has the effect of effectively removing the moisture and cutting oil attached to the aluminum scrap.

In addition, it has the effect of producing an alloy composition closer to the target composition by calculating the amount of alloy components insufficient as a ratio to the target composition.

In addition, the scrap charging temperature, alloying element addition, slag removal temperature is standardized to have an effect of establishing a quality uniformity and defect reduction process of the final product.

In addition, by adding Ti, Zr, AlCuP, Sr has the effect that can be refined aluminum structure.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

1 is a flow chart showing a recycling method of aluminum-based scrap according to an embodiment of the present invention. As shown in FIG. 1, a method of recycling aluminum scrap includes: pretreating aluminum scrap (S10), dissolving aluminum scrap to form a molten metal (S20), and adding an alloying element to the molten metal (S30). And casting the molten metal to which the alloying element is added (S40). Hereinafter, each step will be described in detail.

First, the process of pretreating aluminum scrap is demonstrated in detail. Pretreatment of aluminum scrap includes removing foreign matter and drying the aluminum scrap. The aluminum scrap is transferred to the inlet of the drying furnace through a conveying conveyor for drying.

In this case, a bulk filtering device may be installed in the middle of the conveying path so that the first material having a large volume is not mixed. 2 shows an example of a bulk filtering device. The bulk manure device is configured to remove process inhibiting substances such as long and large wires present in the scrap, thereby preventing the incorporation of relatively large foreign substances contained in the input scrap. The installation primarily removes large steel tools or iron from the scrap.

Next, the transferred scrap is dried in a drying furnace. Chips generated by lathes of aluminum contain large amounts of moisture and cutting oil. Lathe oil consists of approximately 80% moisture and 20% coolant. If it is dissolved without degreasing, it causes a increase in the content of hydrogen. In addition, since moisture and cutting oil do not easily dissolve into the molten metal, chips having a relatively large surface area oxidize faster, increasing the amount of dross and affecting the final quality. do.

Therefore, in order to remove moisture and cutting oil from the aluminum scrap, the aluminum scrap is dried in a drying furnace. As a drying furnace, a round rotary kiln of about 5 m length can be used. At this time, the heater (heater) that is operated as a heat source may be mounted to the upper and lower portions of the drying furnace. The chips are dried inside the rotary drying furnace.

When transferred into the drying furnace through the conveyor, drying occurs inside the drying furnace by two heat sources installed in the drying furnace. As the coil of screw type rotates inside the drying furnace, the chips introduced into the drying furnace are stirred. Accordingly, the drying speed and drying efficiency can be improved. At this time, when the temperature inside the drying furnace is less than 300 ° C, water and cutting oil may not be sufficiently removed, and when it exceeds 420 ° C, aluminum-based scrap may be oxidized. Therefore, the temperature inside the drying furnace is set to 300 ℃ ~ 420 ℃ to dry for 3 to 5 minutes.

The total length of the drying furnace may be about 5m, and the feed rate of the chip in the drying furnace may be controlled by a screw installed therein. Chips dried at the bottom of the drying furnace is discharged to the outside of the drying furnace.

Next, iron powder contained in the dried aluminum scrap is removed. The discharged chips are passed back to the multi-stage foreign matter separator through the conveyor to remove the iron contained in the scrap. Post-cutting is performed for most cast materials. In particular, when using the chip after processing by lathe as the raw material, a large amount of iron generated during processing is contained in the aluminum scrap.

The iron powder has an effect of increasing the iron content in the molten metal during the dissolution process, and the iron powder reacts with aluminum and manganese to form an intermetallic compound. In addition, iron is an element that adversely affects the brittleness of aluminum, an element exhibiting a critical defect. Therefore, in order to lower the iron content in the molten metal it is necessary to remove the iron input initially.

In the method for recycling aluminum-based scrap according to an embodiment of the present invention, the iron having a high iron content in the scrap is removed by using a magnet to remove foreign substances including iron to remove iron using a multi-stage foreign substance separating device. .

3 shows an example of a multi-stage foreign matter separation device. Iron is removed using a multi-stage foreign matter separation device from the scrap that passed through the filtering device as described above. The multi-stage foreign matter separation device may comprise five rolls to which magnetic force is applied. At this time, each roll has a different strength of magnetic force. At this time, a roll having a high magnetic force may be installed at the upper end, and a roll having a low magnetic force may be installed at the lower end.

Next, to melt the aluminum-based scrap after drying and removing the foreign matter as described above to prepare a molten metal. At this time, the reflection furnace melting process can be used for cost reduction and efficiency inventory. The reflector is made in the shape of a round arch, and the heat source may be heavy oil, refined oil, or diesel. Using the above-mentioned oil as the heat source inside the furnace, a strong flame is blown into the furnace through the blower, and the flame is transferred to the material, and excess heat is transferred to the material from the top of the arch-shaped reflection furnace.

Hereinafter, a reflection furnace melting process according to an embodiment of the present invention will be described in detail. 4 is a flowchart showing the procedure of the reflection furnace melting process.

First, the dried scrap is charged to a reflection furnace for the dissolution process. At the time of charging, the main raw material is charged while supplying the heat source inside the reflection furnace. At this time, the total amount of dissolution is not added at once, but the amount of the primary melt is charged to perform dissolution.

This is because the material charged into the reflection furnace is scrap, and the volume thereof is much larger than that of the bulk, so the recovery may be lowered due to oxidation. The larger the surface area is, the faster the reaction with oxygen occurs, especially in a high temperature hot air. Thus, the molten metal is sufficiently made and then further dissolved by adding a second scrap for scrap and composition change.

In this case, a high temperature region of about 700 ° C. is formed in order to promote initial melt formation and rapid dissolution of scrap when the initial reflection furnace is operated.

Next, when the scrap is dissolved, stirring is performed to reduce the temperature deviation of the lower end and the upper end of the melting furnace and to easily dissolve the undissolved scrap. Due to the stirring, the temperature in the molten metal has a uniform temperature distribution than the initial temperature.

The temperature after stirring has a temperature range of 645 ° C. with a low of about 50 ° C., to which a heat source is added for temperature compensation as additional material or scrap is added. The temperature at this time is preferably maintained at the same temperature as before the stirring and further charging.

Next, after the first stirring, the base material is charged to dissolve the scraps for adjusting the total dissolution amount and the secondary currents of the bulk material of the same alloy composition produced in the existing residue and dross together. The loading amount at this time determines the final dissolution amount.

When charging of the base material and scrap is completed, the temperature inside the reflector is lower than the initial temperature. In low temperature alloying, sufficient alloying effect is not seen, so that a sufficient heat source is applied to the alloying temperature.

Next, when the molten metal reaches a sufficient temperature, ash of the slag produced by the slag, which has been previously removed, is introduced into the upper portion of the molten metal. This is to facilitate the separation of the slag in the molten metal by improving the flowability of the slag. The temperature at the time of putting the ash of slag is maintained at 645 degreeC same as the initial stirring temperature.

Next, when the slag flow is sufficient, the slag is removed from the molten metal. At this time, by removing the slag and proceeding to remove the iron powder having a high possibility of mixing from the second scrap charged for the alloy composition control, it is possible to improve the efficiency of the process and shorten the process time. In addition, this can reduce the content of hydrogen and oxygen due to long heating of the product can bring about the cost saving effect of the product quality and process simplification.

In the case of slag and iron removal, the temperature of the molten metal is lowered because the front door of the reflection furnace is opened and the supply of heat source is stopped. The temperature at this time becomes about 628 degreeC.

Next, an alloying element is added to the molten metal from which slag is removed as mentioned above. Before adding the alloying element, the alloy component of the molten metal is analyzed, and the alloy component lacked in the target alloy composition is analyzed and alloyed. At this time, Si is added first and Ni, Cu, and Mg are added in this order. The addition of alloying elements raises the temperature of the melt to about 730 ° C. to increase the rate of alloying and shorten the alloying time.

In addition, additives such as Ti, Sr, P, Zr, and V may be added to improve mechanical properties through refinement of the primary Si and structure refinement. At this time, in order to refine the structure, Ti may be added to 0.4 ~ 0.6wt%. In addition, Zr may be added in an amount of 0.4 to 0.6 wt%. In addition, 40 to 50 ppm of AlCuP may be added, and 0.02 to 0.06 wt% of Sr may be added. When adding an additive beyond the said range, the effect of refinement by addition is small.

Slag is generated since the additive element for alloying is also introduced in a scrap state. Therefore, slag generated after alloying is removed.

Next, after the alloying, the door is opened to remove slag and sufficient stirring is performed to show a uniform alloying component. Due to this stirring, the temperature of the molten metal is lowered to about 700 ° C. and the molten metal is melted at 700 ° C.

At this time, by replenishing the heat source for tapping to prepare for tapping and opening the tapping lever, the aluminum molten metal is tapping out of the tapping tap. In order to maintain the temperature of the molten metal by supplying a heat source during the tapping, the initial molten metal temperature is about 710 ℃, about 10 ℃ higher than when tapping.

Next, primary impurities are removed from the molten aluminum melted by passing through the gate using a porous filter. After the aluminum melting process, the molten metal is injected into a mold and cast in the form of an ingot, which has a long molten metal, unlike general casting. Therefore, the time that the molten metal is in contact with the air is long, and a lot of change may occur in the injection temperature. In addition, the long run times increase the likelihood of impurity ingress.

To improve this problem, a porous filter is installed in the middle of the passage. Such a filter improves the cleaning action of the molten metal. The molten metal which is tapping at a constant speed may flow at a relatively low height, thereby improving the effect of the porous filter. Such a porous filter may be made of a ceramic filter. 5 shows an example of a porous filter.

Impurities contained in the aluminum alloy generally have a higher specific gravity than aluminum, so that the sink sinks under the molten metal during movement. Therefore, the porous filter is made to look at the surface portion so that the molten metal can flow in a lying state. Porous filter serves to remove and adsorb these impurities. In addition, it is possible to improve the adsorption effect by slightly changing the angle of the filter. At this time, the angle of the filter can be installed about 10 ~ 15 °.

Next, the casting process is performed using the molten metal prepared as described above. The molten aluminum from which primary impurities have been removed is transferred to the injection cup. At this time, the injection amount of the molten metal varies depending on the rotational speed of the infusion cup. When the melted molten metal is moved to the rotary injection cup, it is in equilibrium with the atmospheric temperature and becomes about 670 ° C.

The molten metal is injected into a mold through a rotary injection cup, and the same amount of molten metal is injected into the mold when a predetermined time elapses. The melt temperature immediately after being injected into the mold is about 660 ° C. When pouring into the mold, the molten metal should be allowed to flow uniformly, and the molten metal that enters through the molten metal is preferably cooled from the bottom.

When casting aluminum, pay attention to the heating temperature when melting. The injection temperature of aluminum and aluminum alloy is preferably 650 ° C to 750 ° C depending on the process conditions. At this time, care should be taken to prevent oxidation of the surface in the molten state.

The temperature of the molten metal that is tapping out of the reflection furnace may be about 680 ° C to 730 ° C. In view of the long length of the tap water, the injection temperature is about 700 ° C when the tapping temperature is set to 710 ° C.

The temperature of the melt is directly related to the temperature injected into the mold. Because of the long melt, when the temperature of the melt is low, the melt temperature at the melt decreases, which affects the flow and injection of the melt. In addition, when the temperature of the molten metal is high, an oxide film on the surface of the molten metal is formed and a large amount of slag is generated, which causes difficulty in injection.

When the temperature of the molten metal is set at 710 ° C. and injected, the temperature of the molten metal is about 690 ° C. in the first turndish portion. Here it is moved to the rotary injection hole is injected, the temperature is about 670 ℃. The mold temperature affects the microstructure and properties of the aluminum alloy when injected at an injection temperature of 670 ° C.

If impurity or intermetallic compound remaining inside is injected as it is, it will affect the final now. Maintain the temperature of the mold to 200 ~ 300 ℃ to make a continuous injection.

The temperature of the injected mold is circulated through one cycle. When molten metal is injected, the mold temperature rises. However, in order to desorb the ingot from the mold, it is preferable to reduce the volume of aluminum by air cooling after air cooling to facilitate the desorption.

The injected molten metal is injected into a continuous mold, moved through a rail, subjected to primary air cooling during movement, and secondly cooled by a lower spray water cooling method. In this way, by setting the optimum process temperature for each process, it is possible to prevent excessive overheating caused by the process condition setting and improve the quality of the product, and to prevent the loss of energy by supplying excessive heat source.

6 shows an example of a cooling apparatus according to an embodiment of the present invention. The chiller allows for water cooling after air cooling. At this time, by cooling the mold at the bottom of the ingot it can be suppressed to increase the content of oxygen and hydrogen by water. In addition, since water may contact the ingot when high-pressure water is sprayed, it is preferable to cool the mold by spraying water from the lower part by spraying.

Experimental Example

Hereinafter, experimental examples for explaining the effects of the present invention will be described in detail. The experimental examples described below are for explaining the operation and effects of the present invention, and the present invention is not limited to the experimental examples described below.

Experimental Example 1

Volatilization temperature of water and coolant through differential scanning calorimetry (DSC) analysis and thermogravimetric (TG) analysis to set the temperature for removing water and coolant adhering to aluminum scrap Was measured. Based on these results, the temperature of the drying furnace was determined and the treatment effects were analyzed.

DSC analysis was performed to determine the volatilization temperature of the cutting oil contained in the aluminum scrap. The temperature was raised to 550 ° C. at a rate of temperature increase of 5 ° C./min, and the amount of change in current according to the change in weight of the sample was measured. In the TG analysis, the weight reduction ratio was measured according to the temperature of the chip by raising the temperature to 10 ° C./min per minute and raising the temperature to 600 ° C. in the same atmosphere as the drying condition of the chip.

In this experiment, in order to measure the decomposition temperature of the cutting oil in the state of the chip, the cutting oil attached to the chip was heated simultaneously, not in the state of the cutting oil. Therefore, in some cases, the volatilization temperature of the coolant did not appear. These phenomena are unnecessary data in the establishment of drying conditions, so the results are excluded.

7 is a graph showing the results of DSC analysis. The detection of a current change near 96 占 폚 indicates the evaporation temperature of moisture contained in the chip and cutting oil, and the coolant reacts at a small peak near 366 占 폚.

8 shows the results of TG analysis. The initial weight was set to 100% and the weight change with increasing temperature was measured. At about 70 ℃ it was confirmed that 80% of the total weight is evaporated into water. After 80 ℃, there was almost no change in weight. The coolant floating on the chip was about 4% and the weight change up to 600 ℃ was about 84%. A slight weight change occurred after moisture evaporation at about 210 ° C. It is judged that the cutting oil volatilized after evaporation of water at this temperature. About 20% of it remains, and it is judged that it is aluminum and undecomposed coolant.

As a result of the TG test, the water contained in the chip is removed at a temperature of about 100 ° C. or lower in the chip pretreatment process, and most of the cutting oil of the chip is decomposed at about 200 ° C. to 300 ° C. Based on these results, it is judged that the temperature inside the drying furnace is about 300 ° C to 420 ° C.

In the thermal analysis test, decomposition was possible even at low temperatures due to the influence of the temperature increase rate and the holding time.However, in the actual process, the time to heat the chip is much shorter. It is a way to increase the processing speed.

Experimental Example 2

The temperature inside the drying furnace was checked by raising the temperature under the same conditions as the chips inside the drying furnace. The purpose of this study was to establish process conditions to remove water and cutting oil contained in chips without raising the temperature inside the drying furnace above the oxidation temperature of aluminum.

9 to 11 are graphs showing the results of measuring the internal temperature of the drying furnace. The drying furnace measures the temperature of the cooling water and starts or stops the heat source according to the temperature. The temperature of the cooling water was measured by setting the temperature of the cooling water to 70 to 100 ° C. 9 shows the internal temperature of the drying when the temperature of the cooling water is 70 ° C, FIG. 10 shows the internal temperature of the drying when the temperature of the cooling water is 85 ° C, and FIG. 11 shows the internal temperature of the cooling water to 100 ° C. The internal temperature is shown by drying at the time of drying.

As shown in FIG. 9, when the temperature of the cooling water is 70 ° C, the temperature inside the drying furnace is about 300 ° C. The temperature distribution is not uniform, and the internal temperature of the drying furnace changes significantly due to cooling and heating. It was.

As shown in FIG. 11, when the cooling water temperature was 100 ° C, the temperature of the drying furnace was about 450 ° C. Based on this, when the temperature of the cooling water was set to about 85 ℃, it was able to maintain the appropriate temperature of about 400 ℃.

The state of the scrap has a relatively larger surface area than the bulk state, so that the surface oxidation reaction is easily caused by small energy. The temperature inside the drying furnace was slightly higher than the temperature shown by DSC or TG measurement, but no oxidation of scrap occurred. This is because the temperature increased but drying did not affect the scrap for a short time.

Experimental Example 3

The exact iron content, moisture, and cutting oil content of the scrap were quantitatively examined to determine the quantitative value related to the drying amount, which is one element of the pretreatment process.

12 shows the amount of drying after drying the drying furnace under the conditions of Experimental Example 2. FIG. Generally, the scrap after lathe is transported in a rectangular scrap tank. The transferred scrap is put into the tank of the scrap conveying apparatus to dry and separate the iron.

The weight of the scrap tank initially transferred was measured while all scraps were removed from the scrap conveying apparatus and the drying apparatus, and the weight of the scrap subtracted from the tank was set to the weight before the input. In addition, quantitative quantification of the drying amount was performed by measuring the final weight minus the moisture, cutting oil removal amount, and iron weight through a drying furnace.

As shown in FIG. 12, when 1385Kg of the initially introduced scrap was added, the iron content after drying was 377.5Kg, accounting for 27% of the total, and the amount of water and cutting oil was 182.5Kg, 13% of the total, and the weight of the scrap. It was 825 Kg which is 60% of silver content.

Experimental Example 4

The difference of alloy composition with spectroscopic analysis was investigated through wet analysis of the components before and after alloying by wet inductively coupled plasma (ICP) analysis.

In general aluminum alloys, the recovery rate is about 93% for Si, about 98% for Cu and Ni, and about 85% for Mg. It is difficult to predict the exact target composition when the alloying component is added based only on the operator's experience. Therefore, it is possible to approach the target composition more accurately by calculating the alloy ratio with respect to the reference composition and inputting the current composition by spectral component analysis.

Table 1 shows the results obtained by substituting the addition amount of the added alloying element to the target composition, and Table 2 shows the change of composition according to the empirical loading amount by the field worker. Table 1 shows the total weight of the additive alloys according to the total dissolution to the reference composition, the present composition by spectroscopic analysis, and the amount of alloying elements present in the melt. If the current composition is entered, the alloying element of the target composition minus the weight of the current composition is calculated by the formula.

Si Cu Ni Mg Al system Standard composition 12 3 2 One 82 100 15000 Reference charge amount 1800 450 300 150 12300 15000 Current composition 10.88 2.15 1.67 0.742 84.558 100 Current weight 1632 322.5 250.5 111.3 12683.7 15000 Alloy addition amount 168 127.5 49.5 38.7 - 383.7 Recovery rate applied 176.4 130.05 50.49 44.505 401.445

Si Cu Ni Mg Al Before alloying 10.88 2.15 1.67 0.74 83.5 Added alloy amount 160 60 50 60 After alloying 11.71 2.75 1.82 0.99 81.7

At present, 100% recovery of the alloy is almost impossible in the casting process. A change in the recovery rate with the loading of each element occurs. In this formula, the loading amount was calculated by calculating the alloying amount by applying the recovery rate for the final target composition. When comparing Table 1 and Table 2, the alloying weight and actual target composition by the experience of the field workers are relatively similar, but the alloy composition shows a lot of errors in importance.

In particular, in the case of Cu, the loading amount of about 13Kg is changed by the change of 0.1% when the target composition is 3wt%. However, when alloying from 2.15% to 3% of the composition, the required amount was about 130Kg when the recovery rate was calculated as 98%.

By using this formula, it is possible to design an accurate alloy composition compared to the target, and by one calculation of the alloy composition, it is possible to simplify the operation and increase the process yield. This alloy design formula is not limited to one alloy but can be applied to the production of different types of aluminum regeneration now in the same way if the target composition and total dissolution are changed.

Table 3 below shows the results of wet ICP analysis of the components before and after the addition of alloying elements. As shown in Table 3, some errors occur depending on the analysis method. Wet ICP analysis is superior in terms of accuracy between spectroscopic and wet ICP analysis. Based on ICP analysis, all alloying elements were analyzed to have a small amount of alloying elements. Comparing the results of the ICP analysis with the results of the calculation of the charge by Excel, it can be seen that the alloy composition close to the case of adding the charge by the Excel was detected.

Analytical Method Si Cu Ni Mg Al Before addition Spectroscopic analysis 10.88 2.15 1.67 0.74 83.5 ICP Analysis 11.0 2.41 1.72 0.75 83.47 After addition Spectroscopic analysis 11.71 2.75 1.82 0.99 81.7 ICP Analysis 11.9 3.11 1.86 1.07 82.06

Experimental Example 5

The experiment was carried out under the conditions shown in Table 4 by adding the As-Cast test piece and each additive, and FIGS. 13 and 14 are graphs showing cooling curves when the As-Cast test piece was added and the additive was added, respectively. . Table 5 shows the cooling rate change accordingly.

As shown in FIG. 13 and FIG. 14, the peak temperature was 691 ° C. in the case of As cast, and the peak temperature was 682 ° C. and the difference was about 10 ° C. when injected under the same conditions regardless of the addition of additives. Indicated.

In the case of peak temperature, the difference was about 10 ℃, but if you look at the change of cooling temperature per second from injection to 400 ℃, the time taken to solidify up to 400 ℃ is calculated by dividing the temperature by 4.58 ℃ / sec. In the case of the cooling rate of about 4.45 ° C / sec showed little difference.

Thereafter, in the 400 ~ 200 ℃ section, 0.197 ℃ / sec and 0.274 ℃ / sec, respectively, did not show a large difference, but the addition of the additives showed a somewhat faster cooling form than when not added.

Based on this cooling rate, after adding the additive, the size of primary Si and base tissue size were compared. 15 to 18 show the microstructure photograph after the fine grinding by adding the Ti, Zr, AlCuP, Sr as an additive and injecting it into a mold mold to produce a specimen.

At this time, the additive used was added in the form of Al-10wt% Ti, Al-5wt% Zr, Al-Cu19-P1.4 in the form of weight ratio of the pre-made alloy of the mother alloy state, not pure metal state An alloy was used and the results were compared by adding Sr of 4N for Sr.

15 is a microstructure photograph when Ti, 0, 0.2, 0.4, 0.6 wt% is added as an additive. As shown in FIG. 14, 0.2, 0.4, and 0.6 wt% of Ti was added as an additive to examine the effect of the melt-improving treatment. As a result, typical dendrite structures were observed in the test piece without Ti (a). The size is also shown in a coarse structure. However, after the addition of Ti, the microstructure of the dendritic structure was shown as a needle-like Si shape, it can be seen that the size of primary Si also becomes fine. It can be seen that the addition of 0.4wt% (c) exhibits the finest effect, and the addition of 0.6wt% (d) shows a fine structure. The size of primary Si could be observed more easily when 0.4, 0.6wt% was added, and when the amount of additive was increased, the effect of refinement was increased.

16 is a microstructure photograph when Zr is added with 0, 0.2, 0.4, and 0.6 wt% as an additive. As shown in FIG. 15, Zr also showed a similar phenomenon to Ti, and it can be seen that the size of primary Si and process Si is also refined when the amount of addition is increased. When 0.2wt% was added (b) the initial Si size was about 40㎛, but when 0.4wt% was added (c) about 20㎛, 0.6wt% was added (d) It showed a more refined phenomenon.

FIG. 17 is a microstructure photograph when Al, Cu, 0, 20, 40, and 60 ppm are added as an additive, and FIG. 18 is a microstructure photograph when Sr is added with 0, 0.02, 0.04, and 0.06 wt% as an additive. In the case of adding AlCuP and Sr, the treatment effect is very good even though 20 to 60 ppm and 0.02 to 0.06 wt% are added compared to Ti and Zr.

The composition of AlCuP applied in this experiment was Al-Cu19-P1.4, and the amount of 20-60ppm was added.

When the addition amount was increased to 20ppm, 40ppm, the initial Si, the process Si, and the underlying structure were very fine, but when 60ppm was added, the microfine effect was slightly decreased. In the case of AlCuP, the optimum addition amount is considered to be 40-50 ppm.

When Sr was added as an additive, the same phenomenon as AlCuP was exhibited. When 0.02wt% of Sr is added (b), the finest structure can be obtained, and as the addition amount is increased, the degree of refinement becomes smaller, and when 0.06wt% is added (d), the degree of refinement is small and the dendrite is formed. Could confirm.

Addition of Ti, Zr, AlCuP, and Sr as the secondary alloy as a secondary alloy, and then injected into a mold mold preheated to 200 ° C. Micro Vickers Hardness Test Was carried out.

Indentation test was performed by applying indentation load for 100 g for 10 seconds. A total of 15 random indentations were performed and the hardness test results were derived as the average of the hardness values except for the minimum and maximum values.

In the case of the As cast specimen, the average hardness value was measured to be about 110 Hv, and the hardness of the test specimen after the addition of additives was slightly increased, and the hardness was increased according to the microstructure of the microstructure. You can check. In the case of Ti, the hardness of 145Hv was the highest in the specimen added 0.4wt%, and in the case of Zr, the hardness was the same as the result of showing the finest microstructure in the specimen added 0.4wt%. .

However, AlCuP and Sr were found to be fine, but hardness was slightly lower than Ti and Zr in hardness test, but higher hardness than As Cast specimen. AlCuP and Sr also showed the highest hardness when 40 ppm and 0.04 wt% were added in the same way as the microstructure.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings, and the present invention is also provided. Naturally, it belongs to the range of.

1 is a flowchart illustrating a recycling method of aluminum scrap according to an embodiment of the present invention.

2 shows a bulk manure device.

3 shows a multi-stage foreign matter separator.

Figure 4 is a flow chart showing a dissolution process according to an embodiment of the present invention.

5 is a schematic view showing a porous filter.

6 shows a cooling device.

7 is a graph showing the DSC analysis results in the experimental example of the present invention.

8 is a graph showing the results of TG analysis in the experimental example of the present invention.

9 to 11 are graphs showing the results of measuring the internal temperature of the drying furnace in the experimental example of the present invention.

12 shows the drying amount after drying the drying furnace under the conditions of Experimental Example 2. FIG.

13 and 14 are graphs showing cooling curves when an As-Cast test piece is added and an additive is added, respectively.

15 to 18 show microstructure photographs of specimens prepared by adding Ti, Zr, AlCuP, and Sr as additives, respectively.

Claims (14)

Drying the aluminum scrap in a drying furnace having an internal temperature of 300 to 420 ° C., Dissolving the dried aluminum scrap to form a molten metal, and Injecting the molten metal into a mold and casting the molten metal Recycling method of aluminum-based scrap comprising a. According to claim 1, The method for recycling aluminum-based scrap further comprising the step of removing foreign matter containing iron from the aluminum-based scrap. According to claim 1, Removing the foreign matter, Removing the foreign matter by using a bulk filtering device, and Removing foreign matter by using magnetic force Recycling method of aluminum-based scrap comprising a. According to claim 1, Recycling method of aluminum-based scrap to perform the step of drying the aluminum-based scrap for 3 to 5 minutes. According to claim 1, Forming the molten metal, Charging the dried aluminum scrap into a furnace at a temperature of 690-710 ° C., Adding an alloying element to the molten metal at a temperature of 720 to 730 ° C., and Removing slag at a temperature of 690 ~ 710 ℃ Recycling method of aluminum-based scrap comprising a. According to claim 1, The method of recycling the aluminum scrap further comprises the step of adding an additive for microstructure of the molten metal. The method according to claim 6, The additive is a recycling method of aluminum-based scrap containing 0.4 ~ 0.6wt% Ti. The method according to claim 6, The additive is a recycling method of aluminum-based scrap containing 0.4 ~ 0.6wt% Zr. The method according to claim 6, The additive is a recycling method of aluminum-based scrap containing 40 ~ 50 ppm AlCuP. The method according to claim 6, The additive is a method for recycling aluminum-based scrap containing 0.02 ~ 0.06wt% Sr. According to claim 1, The method of recycling the aluminum-based scrap to continuously cast by maintaining the temperature of the mold at 200 ~ 300 ℃ in the casting step. According to claim 1, The method for recycling aluminum-based scrap further comprises the step of removing impurities from the molten metal by using a porous filter. The method of claim 12, The porous filter is a method for recycling aluminum-based scrap is a ceramic filter. According to claim 1, The drying furnace is a rotary kiln (rotary kiln) recycling method of aluminum-based scrap.

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