CN86103277A - Remove the method for iron and titanium impurities and refining eutectic aluminium-silicon alloy - Google Patents

Abstract

A kind of method of removing iron and titanium impurities and refining cocrystallized Al-Si alloy comprises: al-si eutectic alloys with chromium is melted in manganese, the gained melt is cooled to 590～660 ℃ and at the chilled melt of said temperature scope inner filtration, wherein use chromium and titanium with such quantity, promptly the mass ratio at chromium and manganese equals (0.1～20): 1 o'clock, make chromium and manganese quality and with the quality of iron and titanium and ratio be (0.2～1.1): 1.

Description

Method for removing iron and titanium impurities and refining eutectic aluminum-silicon alloy

The present invention relates to nonferrous metallurgy and mechanical engineering, and more specifically to a method for refining eutectic aluminum-silicon alloys by removing iron and titanium impurities. At high concentrations, these impurities have been found to be detrimental to the industrial properties of aluminum-silicon alloys (G.B. Stroganov, V.A. Rotenberg, G.B. Gershman, "Aluminum-Silicon Alloys," pp. 127, 128, 132-134, published by the Metallurgical Publishing House in Moscow, 1977). After alloying and melting, the refined aluminum-silicon alloy is used to cast various complex structural parts in the automotive, tractor, and related industries, such as pistons and cylinder heads for internal combustion engines and high-pressure pump housings.

The method for refining eutectic aluminum-silicon alloys by removing iron and titanium impurities is well known in existing processes and technologies. Specifically, when the mass ratio of chromium to manganese is (0.5-1):1, the eutectic aluminum-silicon alloy must be melted with chromium and manganese, with the mass ratio of the sum of chromium and manganese to the mass ratio of the sum of iron and titanium impurities being (1.2-2.0):1. Solid aluminum is then added to the resulting melt, and the melt is cooled to 615-620°C. The process of cooling the melt to this temperature is characterized by the formation of intermetallic compounds of iron, chromium, manganese, aluminum, and silicon, as well as intermetallic compounds of titanium, chromium, manganese, aluminum, and silicon. The cooled melt is then filtered within the above temperature range to remove the iron and titanium contained in these intermetallic compounds (Inventor's Certificate USSR No. 1108122, IPCC 22C1/06, "Discovery and Invention" Publication No. 30, 1984).

Note that this well-known method of refining eutectic composition Al-Si alloys has the following disadvantages:

1. During the filtration stage of the aluminum-silicon melt to remove iron and titanium mixed in the intermetallic compounds, the aluminum-silicon melt yield is low. When the iron and titanium contents of the aluminum-silicon melt before filtration are 2% and 1% by mass, respectively, the yield is 88.1%, while 11.9% of the melt is lost as filter residue. The residue is a mechanical mixture of intermetallic compounds and a certain amount of crystallized aluminum-silicon alloy. In this case, the aluminum content of the filter residue is high, reaching 80.3% by mass. This disadvantage increases the initial cost of refining the eutectic aluminum-silicon alloy and the aluminum consumption during alloy production.

2. The expensive metals (chromium and manganese) involved in forming the above-mentioned intermetallic compounds require high consumption. Therefore, for every unit of iron and titanium removed, 1.2 to 2.0 units of chromium and manganese are required, which also increases the initial cost of refining the aluminum-silicon alloy.

3. Especially when refining aluminum-silicon alloys with high iron and titanium contents, the degree of iron and titanium removal from the eutectic aluminum-silicon alloy is low. For example, when the iron and titanium contents in the aluminum-silicon melt before filtration are 0.8% by mass and 0.4% by mass, respectively, the ratio of the sum of the mass of chromium and manganese to the sum of the mass of iron and titanium is 1.2:1, and the mass ratio of chromium to manganese is 0.5:1, the degree of iron removal from the eutectic aluminum-silicon melt is 27.5%, while the degree of titanium removal from the eutectic aluminum-silicon melt is 67.5%.

The low degree of refining of aluminum-silicon alloy will result in poor industrial properties of the refined aluminum-silicon alloy produced.

The specific purpose of the present invention is to solve the problems in the method of refining aluminum-silicon alloy by removing iron and titanium impurities, and to select such a mass ratio between chromium, manganese, iron and titanium as to increase the yield of aluminum-silicon melt in the filtration stage, reduce the consumption of expensive metals chromium and manganese, increase the degree of removal of iron and titanium impurities from the refined aluminum-silicon alloy, and at the same time improve the quality of the refined alloy.

The problems encountered in the above-mentioned method for refining aluminum-silicon alloys by removing iron and titanium impurities can be solved by melting the eutectic aluminum-silicon alloy together with chromium and manganese, cooling the resulting melt to a temperature of 590-660°C, and filtering the cooled melt within the above-mentioned temperature range. When applying the method of the present invention, the mass ratio of chromium to manganese used is (0.1-20):1, and the ratio of the sum of the mass of chromium and manganese to the sum of the mass of the iron and titanium impurities is (0.2-1.1):1.

The use of chromium and manganese in such quantities that, when the mass ratio of chromium to manganese is between 0.1 and 20:1, the ratio of the sum of the mass of chromium and manganese to the sum of the mass of iron and titanium is between 0.2 and 1.1:1, helps to increase the yield of the aluminum silicon melt during the filtration stage to 98.8% (while reducing the aluminum content in the filter residue by an average of 15.4%), reduces the total consumption of chromium and manganese by nearly 4.75 times, increases the degree of refining by removing iron from the eutectic aluminum silicon alloy to 80.5% and the degree of refining by removing titanium to 94%, and improves the quality of the refined alloy. For example, as the iron content of the aluminum silicon alloy decreases from 0.7% to 0.37% by mass and the titanium content decreases from 0.25% to 0.06% by mass, the elongation of the refined alloy increases from 2.5% to 3.7%, or by a factor of 0.5.

The advantages of the method of the present invention described above are due to the following reasons.

When chromium and manganese are used in a mass ratio of (0.1-20) : 1 and the ratio of their mass sum to the mass sum of iron and titanium impurities is (0.2-1.1) : 1, the cooled aluminum silicon melt contains the intermetallic compounds listed in Table 1.

Table 1

NN    Intermetallic compound    Chemical composition of intermetallic compound [% (mass)]

Al Si Fe Ti Cr Mn

1.Cr _0,05 Fe _0,5 Al _1,5 Si 40,9 28,7 27,7 - 2,5 -

2.Cr _0,03 Fe _0,5 Al _1,1 Si _1,4 30,3 38,5 29,2 - 2,0 -

3.Fe _0,5 Cr _0,03 Mn _0,02 Al _1,5 Si 41,1 28,8 27,5 - 1,5 1,1

4.Fe _{0, 5} Cr _{0, 01} Mn _{0, 02} Al _1, 1 Si _1, 4 30, 9 38, 5 28, 3 - 1, 0 1, 3

5.Fe _{0, 3} Cr _{0, 4 Si 1,} 1 Ti ₀ , 6 - 30, 5 17, 5 28, 1 20, 9 -

6.Fe _{0, 4} Cr _{0, 2} Mn _0, 1 Si _{1, 2} Ti ₀ , 6 - 34, 0 20, 1 26, 8 11, 3 7, 8

7.Cr _{0, 3} TiSi ₁ , 3 - 35, 7 - 48, 8 15, 5 -

8.Cr _{0, 3} Ti _{0, 7} Si 0, 8 Al _1, 1 30, 5 22, 8 - 31, 5 15, 2 -

9.Fe _{0, 4} Cr _{0, 08} Mn _{0, 07} Al 1, 3 SiTi _0, 3 30, 5 28, 5 20, 2 12, 5 4, 2 4, 1

10.Fe _{0, 4} Cr _0, 1 AlSi _1, 1 Ti _0, 3 25, 8 31, 0 23, 2 14, 8 5, 2 -

The formation of intermetallic compounds of the compositions listed above is most favorable.

The above cited intermetallic compounds crystallize into large sized polyhedrons, spheres and dendrites during cooling and are easily separated from the cooled eutectic Al-Si alloy during the filtration stage to remove the iron and titanium.

When using the previously known method of removing iron and titanium impurities to refine the eutectic aluminum-silicon alloy, the metal compounds formed in the cooled aluminum-silicon melt are listed in Table 2. Table 2

NN    Intermetallic compound    Chemical composition of intermetallic compound [% (mass)]

Al Si Fe Ti Cr Mn

1    2    3    4    5    6    7    8

1.Cr _{0, 4} Mn _{0, 2 Al 2 , 1 Si 0,} 4 58, 2 10, 5 - - 20, 1 11, 2

2.CrAl ₇ 78, 4 - - - 21, 6 -

3.Cr _0,05 Mn _0,2 Al _3,2 87,0 - - - 2,5 10,5

4.Cr _{0, 6} Al ₂ Si _0, 6 52, 7 16, 7 - - 31, 0 -

5.MnAl ₆ 74, 6 - - - - 25, 4

6.Mn _{0, 5} Al _{2, 2} Si 0, 4 60, 3 12, 4 - - - 25, 4

7.Cr _{0, 2} Fe _{0, 4} Al 2 _{, 3} Si 0, 4 61, 3 9, 7 20, 9 - 8, 1 -

8.Cr _{0, 3} Fe _{0, 3} Al 1 _{, 7 Si 0,} 9 46, 0 24, 1 14, 8 - 15, 1 -

9.Fe _{0, 3} Cr _0, 2 Mn _{0, 1} Al _{2, 2 Si 0,} 4 60, 1 10, 7 14, 0 - 8, 0 7, 2

10.Fe _{0, 2} Cr _{0, 2} Mn _0, 2 Al _{1, 7} Si _0, 9 45, 6 24, 0 12, 1 - 8, 8 9, 5

11.Fe _{0, 2} Mn _0, 3 Al _2, 4 Si _0, 3 64, 6 8, 9 11, 1 - - 15, 4

12.Fe _{0, 1} Cr _{0, 6 Si 1, 7} Ti ₀ , 3 - 47, 2 4, 7 15, 2 32, 9 -

13.Fe _{0, 1} Cr _0, 3 Mn _0, 3 Si _{1, 8} Ti ₀ , 3 - 48, 8 7, 1 13, 8 15, 0 15, 3

14.Cr _{0, 5} Ti _{0, 5} Si 0, 4 Al _1, 5 41, 2 11, 6 - 22, 0 25, 2 -

15.Fe _{0, 2} Cr _{0, 2} Mn _0, 2 Al _{1, 4} SiTi _0, 1 38, 7 25, 9 10, 5 6, 3 10, 1 8, 5

16.Fe _{0, 5} Cr _{0, 3} Al 1, ₅ Si 0, 8 Ti _0, 2 40, 1 21, 2 12, 6 10, 3 15, 8 -

The removal of iron and titanium impurities from the intermetallic compounds listed in Table 1 (rather than from the intermetallic compounds listed in Table 2) during the filtration of the aluminum-silicon melt ensures the achievement (solution) of the aforementioned object (problem) because the intermetallic compounds formed in the aluminum-silicon melt using the refining method of the present invention contain higher concentrations of iron and titanium and lower concentrations of chromium, manganese, and aluminum than those formed in aluminum-silicon _melts using conventional _{refining methods} . Furthermore, using the method _of refining the aluminum-silicon alloy of the present invention, the cooling process is not accompanied by the formation _{of the} intermetallic compounds _CrAl7 , _{Cr0.05Mn0.2Al3} , _{Cr0.4Mn0.2Al2.1Si0.4 , MnAl6} , _{Cr0.6Al2Si0.6} , _{and Mn0.5Al2.2Si0.4 .} However, the above-mentioned intermetallic compounds are formed using the methods known in the past, and the removal of iron and titanium impurities from the aluminum silicon melt during the filtration stage also increases the consumption of chromium, manganese, aluminum and silicon, reduces the yield of the aluminum silicon melt and increases the aluminum content in the filter residue.

The formation of the intermetallic compounds listed in Table 1, with high iron and titanium contents, helps to reduce the total mass of the intermetallic compounds. This, in turn, reduces the height of the intermetallic layer on the filter, thereby reducing the loss of aluminum-silicon alloy crystallized in the filter residue, reducing the aluminum content in the filter residue, and increasing the yield of refined alloy.

The limiting ratio of the sum of the masses of chromium and manganese to the sum of the masses of iron and titanium of (0.2 to 1.1):1, and the limiting ratio of the mass of chromium to manganese equal to (0.2 to 20):1 are determined by the following conditions.

When the mass ratio (Cr+Mn):(Fe+Ti) in the eutectic aluminum-silicon melt falls below _0.2 :1, the amounts of chromium and manganese are insufficient to form intermetallic compounds of the aforementioned optimal composition (Table 1). In this case, the _{Fe0.5Al2.3Si0.5} type _{intermetallic} compounds formed in the melt have a low iron content and a high aluminum content, which reduces the degree of refining to remove iron and titanium impurities from the eutectic aluminum-silicon melt _{and deteriorates} the quality of the refined alloy because some of the small particles of these intermetallic compounds are converted into the refined alloy. Furthermore, if the mass ratio falls below the minimum limit, the aluminum content in the filter residue increases because the residue is enriched _{with Fe0.5Al2.3Si0.5} type _{intermetallic} compounds, _which clearly have a high aluminum content.

When the mass ratio (Cr+Mn) : (Fe+Ti) in the aluminum-silicon melt is higher _than 1.1:1, the excess chromium and manganese relative to the _{iron and} titanium impurities will form, during cooling, the _{intermetallic} compounds _{Cr0.4Mn0.2Al2.1Si0.4} , _{Cr0.05Mn0.2Al3.2} , _{Cr0.6Al2Si0.6} , _CrAl7 , _MnAl6 and other intermetallic compounds listed in _Table 2. These intermetallic compounds have high concentrations of chromium _, manganese _and aluminum and low concentrations of iron and titanium. At _the same time _, some of the intermetallic compounds formed (for _example , _{Cr0.05Mn0.2Al3.2} , _{CrAl7MnAl6 , Cr0.6Al2Si0.6} , _{Mn0.5Al2.2Si0.4 )} do _not contain any iron or _titanium . During the filtration of the aluminum-silicon melt, the removal of these intermetallic compounds, thereby removing iron and titanium, results in a decrease in the yield of the aluminum-silicon melt and an increase in the aluminum content in the filter residue. Furthermore, if the above mass ratio exceeds the maximum value, it will also lead to excessive consumption of the precious metals chromium and manganese, without improving the degree of refining of the aluminum-silicon alloy to remove iron and titanium impurities.

A reduction in the chromium to manganese mass ratio (below 0.1:1) impairs the conditions for forming intermetallic compounds of the most favorable composition listed in Table 1 in the aluminum-silicon melt. Furthermore, due to the high manganese content and low chromium content in the aluminum-silicon alloy, manganese plays a major role in the formation _of intermetallic compounds containing _iron and titanium. In this case, the intermetallic compounds formed are _{Fe0.2Mn0.3Al2.4Si0.3} , _{Mn0.5Al2.3Si0.4} , _{Fe0.2Mn0.3Al2.3} , and _MnAl6 . Their removal during _the filtration stage reduces the yield of _the refined aluminum _- silicon alloy, increases the aluminum content in the filter residue _, and reduces _the degree of iron and titanium removal from the aluminum-silicon alloy, while also deteriorating the quality of the refined alloy. This is because the formed intermetallic compounds Fe _0.2 Mn _0.3 , Al _2.4 Si _0.3 , Mn _0.5 Al _2.3 Si _0.4 , Fe _0.2 Mn _0.3 Al _2.3 , and MnAl ₆ are enriched with cobalt, while the intermetallic compounds Mn _0.5 Al _2.3 Si _0.4 and MnAl ₆ do not contain any iron and titanium impurities.

When the chromium to manganese mass ratio exceeds 20:1, excess chromium relative to manganese is observed _in the aluminum silicon melt. In this case, the _aluminum silicon melt is primarily composed of chromium- _and aluminum-rich intermetallic compounds, such _{as CrAl7} , _{Cr0.5Ti0.5Si0.4Al1.5} , _{Fe0.1Cr0.6Si1.7Ti0.3} , _{Cr0.2Fe0.4Al2.3Si0.4} , _{and Cr0.3Fe0.3Al1.7Si0.9 .} This results _in a lower aluminum silicon melt yield during _the filtration stage and increases _the aluminum content in _the filter residue _without improving the degree of refining _of the aluminum silicon alloy to remove iron and titanium impurities.

It should be noted that the ratio of the sum of the masses of chromium and manganese to the sum of the masses of iron and titanium impurities in the claim is equal to (0.2 to 1.2):1, which is interrelated with the mass ratio of chromium to manganese equal to (0.1 to 20):1. The combined effect of the two ensures that the above-mentioned advantages are achieved.

When the aluminum silicon melt is cooled below 590°C and filtered below 590°C, the eutectic aluminum silicon melt begins to crystallize. It loses fluidity and cannot be filtered, or is filtered with great loss in the filter residue.

When an aluminum-silicon melt is cooled to a temperature above 660°C and filtered at this temperature, the degree of refining of the aluminum-silicon melt to remove iron and titanium impurities decreases. This is because at temperatures above 660°C, either the intermetallic compounds listed in Table 1 cannot be fully formed, and iron and titanium cannot be removed from the aluminum-silicon alloy; or the process of forming the above-mentioned intermetallic compounds cannot be completed. In this case, the intermetallic compounds contain relatively small amounts of iron and titanium and crystallize into a few small grains, which allows iron and titanium to be incorporated into the aluminum-silicon melt during the filtration stage, thereby doping iron and titanium into the alloy. During the further crystallization process of such an aluminum-silicon alloy, that is, during the casting of various products using this alloy, the intermetallic compound crystals grow, thereby reducing the working properties of the alloy (i.e., the working properties of the products made from this alloy). 0.2 Mn 0.1 Si 1.2 Ti 0.6 -0.5～15，Cr 0.3 TiSi 1.3 -0.5～15，Fe 0.4 Cr 0.2 Mn 0.1 Si 1.2 Ti 0.6 -0.5～15，Cr _0.05 Fe _0.5 Al 1.5 Si -0.5～15，Cr 0.03 Fe 0.5 Al 1.1 Si 1.4 -0.5～30，Fe 0.5 Cr 0.03 Mn 0.02 Al _1.5 Si -3～15，Fe _0.5 Cr _0.01 Mn 0.02 Al _1.1 Si _1.4 -3～15，Fe _0.3 Cr _0.4 Si _1.1 Ti _0.6 -0.5～15，Cr _{0.3 TiSi 1.3 -0.5} ～15，Fe _0.4 Cr _0.2 Mn _0.1 Si _1.2 Ti _0.6 -0.5～15，Cr 0.05 Fe _0.5 Al _1.5 Si -0.5～15，Cr _0.03 Fe _0.5 Al _1.1 Si _{1 0.6} -3～20, Fe _0.4 Cr _0.08 Mn _0.07 Al _1.3 SiTi _0.3 -3～20, Fe _0.4 Cr _0.1 AlSi _1.1 Ti _0.3 -3～20, Cr _0.3 Ti _0.7 Si _0.8 Al _1.1 -0.5～25.

Thus, for example, when the ratio of the mass sum of chromium and manganese to the mass sum of iron and titanium impurities remains unchanged at 0.6:1, and the mass ratio of chromium and manganese changes from 0.4:1 to 10:1, the contents of the intermetallic compounds Cr _0.03 Fe _0.5 Al _1.1 Si _1.4 and Fe _0.3 Cr _0.4 Si _1.1 Ti _0.6 in their total mass increase from 3% and 2% to 20% and 9% respectively.

Based on the above considerations, we recommend the following two solutions to implement the method of the present invention:

In a first embodiment of the method, when using chromium and manganese in quantities such that their mass sum relative to the mass sum of iron and titanium impurities is in the ratio of 0.2 to 0.69:1, it is recommended that the mass ratio of chromium to manganese be maintained at 0.5 to 20:1. In this case, the intermetallic compounds primarily formed in the aluminum-silicon melt have the most favorable compositions: Cr _0.03 Fe _0.5 Al _1.1 Si _1.4 , Fe _0.3 Cr _0.4 Si _1.1 Ti _0.6 , Cr _0.3 Ti Si _1.3 , and Fe _0.4 Cr _0.1 Al Si _1.1 Ti _0.3 . These intermetallic compounds contain the lowest concentrations of aluminum and the highest concentrations of iron and titanium. The aluminum-silicon melt with this intermetallic compound composition removes iron and titanium during the filtration stage, ensuring the high efficiency of the refining method of the present invention.

In a second embodiment of the method, when the amounts of chromium and manganese are such that their combined mass ratio to the combined mass ratio of iron and titanium impurities is (0.7-1.1):1, it is recommended that the mass ratio of chromium to manganese be maintained at (0.1-0.4):1. Thus, for the above situation, the most favorable compositions of the intermetallic compounds primarily formed in the aluminum-silicon melt are: Fe _0.5 Cr _0.01 Mn _0.02 Al _1.1 Si _1.4 and Fe _0.14 Cr _0.2 Mn _0.1 Si _1.2 Ti _0.6 . These intermetallic compounds are characterized by high iron and titanium contents and low chromium, manganese, and aluminum contents. Removing iron and titanium from these intermetallic compounds ensures the high efficiency of the refining method of the present invention.

It should be noted that the advantages of the process of the present invention can be obtained when any mass ratio of chromium, manganese, iron and titanium is within the disclosed limits compared to previously known processes, and the best results can still be obtained when the disclosed process is implemented according to the above-cited embodiment.

The refined eutectic aluminum-silicon alloy, from which iron and titanium impurities have been removed according to the claimed method, can also be obtained by various known methods. For example, the aluminum-silicon alloy can be obtained by melting silicon, aluminum, and/or their primary and secondary alloys (aluminosilicates, aluminum iron, etc.) together in a metallurgical mixing furnace, an induction heating furnace, or a gas furnace. The metals and alloys listed above are used in proportions such that the resulting aluminum-silicon alloy has a eutectic composition and contains 10-14% by mass of silicon.

If an ore reduction furnace and aluminosilicate raw materials are commercially available, a refined aluminum-silicon eutectic alloy, free of iron and titanium impurities, can be obtained by the following method. A briquette charge containing the aluminosilicate raw materials and a carbon reducing agent is smelted in an ore reduction furnace by ore reduction smelting to produce an aluminum-silicon alloy with the following hypereutectic composition (% by mass): 30-40% silicon, 2-5% iron, 0.8-3% titanium, and the remainder aluminum. To remove non-metallic impurities from the alloy, the hypereutectic aluminum-silicon alloy is treated with a flux in a ladle and then poured into an alloy mixing furnace. Depending on the silicon content of the hypereutectic aluminum-silicon alloy, the hypereutectic aluminum-silicon alloy is diluted with aluminum and/or a primary or secondary aluminum-based alloy to a eutectic composition (10-14% silicon by mass).

Therefore, a prerequisite for using the disclosed refining method is that the initial eutectic aluminum-silicon alloy containing iron and titanium impurities is produced by any known method.

In addition, secondary aluminum-silicon alloys doped with iron and titanium impurities can be used as aluminum-silicon alloys to be refined. The secondary aluminum-silicon alloys containing either hypoeutectic or hypereutectic components should be made to produce eutectic components before refining.

The method of the present invention for refining the eutectic aluminum-silicon alloy by removing the iron and titanium impurities is proposed to be carried out in the following manner.

An alloy mixture of Al-Cr and Al-Mn is prepared in a predetermined ratio in an induction heating furnace at 750-1100°C. The resulting alloy mixture is then melted in an alloy mixing furnace with a starting eutectic aluminum-silicon alloy containing iron and titanium impurities to produce a eutectic aluminum-silicon alloy. If the addition of the aluminum-based alloy mixture to the starting eutectic aluminum-silicon alloy results in a hypoeutectic aluminum-silicon alloy melt (silicon content less than 10% by mass), silicon in an amount sufficient to produce a eutectic aluminum-silicon melt must be added to the alloy mixture and/or the starting aluminum-silicon alloy.

The amount of the alloy mixture added to the aluminum silicon melt is determined based on the required mass ratio of chromium and manganese to the mass ratio of iron and titanium impurities and the mass ratio of chromium to manganese.

To ensure uniform mixing of the components of the resulting aluminum-silicon melt, it is recommended to mix the melt for 5 to 30 minutes. Once mixing is complete, it is recommended to hold the melt for 10 to 15 minutes to remove non-metallic impurities. During this holding period, the melt cools. However, the required temperature (590-660°C) is not reached during this time. Therefore, solid aluminum or an aluminum-based alloy is added to the cooled aluminum-silicon melt at a mass ratio of solid aluminum to cooled aluminum-silicon melt of 0.01-0.1:1, forcing the melt to cool.

If solid aluminum or aluminum-based alloy is added to a cooled eutectic aluminum-silicon melt, resulting in a hypoeutectic melt, some silicon must be added to the cooled aluminum-silicon melt, and the amount of silicon added is exactly the amount required to obtain the cooled eutectic aluminum-silicon melt.

In order to speed up the cooling process, an effective approach is to continuously stir the aluminum silicon melt and continuously measure the temperature of the melt with a tungsten-rhenium thermocouple.

When the melt temperature is 590-660°C, the cooled eutectic aluminum-silicon melt is filtered.

While being filtered, the fusible eutectic aluminum-silicon melt permeates the filter into the metal receiver located below the filter. Due to the filtering effect, the high-melting intermetallic compounds containing iron and titanium as well as the various components listed in Table 1 are separated from the aluminum-silicon melt and transferred to the filter residue, thereby removing iron and titanium and refining the aluminum-silicon alloy.

The refined aluminum-silicon alloy is then cast into the desired product by various known methods.

The following are technical and economic indicators of the claimed and previously known refining methods, such as the yield of the aluminum silicon melt in the filtration stage, the aluminum content in the filter residue, the consumption of chromium and manganese, and the degree of refining of the aluminum silicon alloy to remove iron and titanium impurities.

The yield of the aluminum silicon melt in the filtration stage is calculated according to the mass percentage of the aluminum silicon melt before and after filtration.

The aluminum alloy in the filter residue can be determined by chemical analysis or spectroscopic analysis of the filter residue.

The chromium and manganese consumption is determined by dividing the sum of the masses of chromium and manganese used by the sum of the masses of iron and titanium in the initial aluminum-silicon alloy.

The degree of refining of the aluminum-silicon alloy to remove iron and titanium impurities is determined by dividing the difference in the iron and titanium contents in the aluminum-silicon melt before and after filtration by the contents of the above impurities in the aluminum-silicon melt before filtration, and is expressed as a percentage.

To better understand the present invention, several examples of embodiments of the present invention are provided below. Table 3, provided following each example, summarizes the technical and economic indicators of the claimed invention for Examples 1-9 (yield of the aluminum-silicon melt during the filtration stage for iron and titanium removal, aluminum content in the filter residue, cumulative chromium and manganese consumption per unit mass of iron and titanium impurities removed from the aluminum alloy to be refined, and the degree of iron and titanium impurity removal from the aluminum-silicon alloy). Table 3 also provides elongation data for the refined aluminum-silicon alloy, demonstrating its ductile properties. Furthermore, for comparison purposes, Table 3 presents the technical and economic indicators obtained using conventional methods according to Examples 10 and 11, as well as the resulting elongation data for the refined aluminum-silicon alloy.

Example 1

The composition of the refined eutectic aluminum-silicon alloy is [% by mass]: silicon 13.9; iron 0.8; titanium 0.4; and the remainder aluminum.

The aluminum-silicon alloy having the above-mentioned composition at a temperature of 750°C is placed in an alloy mixing furnace and melted together with the alloy mixtures Al-Mn and Al-Cr produced in an induction heating furnace and heated to 800°C and 820°C respectively. When the mass ratio of chromium to manganese is 0.1:1, the amount of the alloy mixture must be ensured so that the ratio of the mass sum of chromium and manganese to the mass sum of iron and titanium impurities is 0.1:1.

The eutectic aluminum-silicon alloy is melted together with chromium and manganese. The resulting aluminum-silicon melt has the following eutectic composition [% (mass)]: silicon 12.5; iron 0.8; titanium 0.4; chromium 0.02; manganese 0.22, and the balance aluminum.

The resulting eutectic aluminum-silicon melt had a temperature of 760°C. To cool the melt to 590°C, a small amount of solid aluminum was added to the melt, with a mass ratio of aluminum to melt equal to 0.08:1. The temperature of the cooled aluminum-silicon melt was continuously measured. When the temperature of the aluminum-silicon melt reached 590°C, the cooling process was stopped and the melt was filtered at the same temperature.

The refined eutectic aluminum-silicon melt that had passed through the filter was collected in a metal receiver located below the filter. The melt had the following composition [% (mass)]: silicon 11.3; iron 0.46; titanium 0.12; chromium 0.01; manganese 0.08; and the remainder aluminum.

The intermetallic compounds remaining on the filter contain iron and titanium.

Example 2

The refined eutectic aluminum-silicon alloy has the following composition [% (mass)]: silicon 13.2; iron 1.4; titanium 0.7; the balance is aluminum.

The aluminum-silicon alloy with the above composition at 670°C is placed in an alloy mixing furnace and melted together with the Al-Cr and Al-Mn alloy mixtures produced in an induction heating furnace at 900°C and 780°C, respectively. The amount of alloy mixture must be such that, when the mass ratio of chromium to manganese is 10:1, the ratio of the sum of the mass of chromium and manganese to the sum of the mass of iron and titanium impurities is 0.65:1.

The aluminum-silicon alloy was stirred for 15 minutes to ensure uniform mixing of the components. This produced an aluminum-silicon melt having the following eutectic composition [% by mass]: silicon 12.0; iron 1.4; titanium 0.7; chromium 1.24; manganese 0.12; and the remainder aluminum.

The temperature of the obtained aluminum silicon melt was 690° C. The melt was held for 30 minutes to remove non-metallic impurities and cooled to 660° C. The cooled melt was then filtered at the same temperature.

The refined aluminum-silicon melt collected in the metal receiver had the following eutectic composition [mass %]: silicon 11.5; iron 0.34; titanium 0.07; chromium 0.45; manganese 0.04; and the remainder aluminum.

Example 3

The refined eutectic aluminum-silicon alloy has the following composition [% (mass)]: silicon 13.6; iron 2.0; titanium 1.0; the balance being aluminum.

The refined aluminum-silicon alloy with the above composition at 730°C is placed in an alloy mixing furnace and melted together with the Al-Cr and Al-Mn alloy mixtures produced in an induction heating furnace at 930°C and 780°C, respectively. The amount of the alloy mixture must be such that, when the mass ratio of chromium to manganese is 20:1, the ratio of the sum of the mass of chromium and manganese to the sum of the mass of iron and titanium impurities is 1.1:1.

The aluminum-silicon melt was mixed for 25 minutes to ensure uniform mixing of its components. The resulting aluminum-silicon melt had the following eutectic composition (mass %): silicon 12.1%; iron 2.0%; titanium 1.0%; chromium 3.15%; manganese 0.15%; the remainder being aluminum. The resulting melt had a temperature of 780°C.

In order to remove non-metallic impurities from the melt and to cool the melt a little, the aluminum silicon melt was held for 40 minutes, so that its temperature dropped to 730° C. In order to cool the aluminum silicon melt to 625° C., solid aluminum was added to the melt with a mass ratio of aluminum to the cooled melt of 0.05:1, and then the cooled melt was filtered at 625° C.

The refined aluminum-silicon melt collected in the metal receiver had the following eutectic composition [mass %]: silicon 11.6; iron 0.42; titanium 0.10; chromium 0.7; manganese 0.04; the remainder being aluminum.

Example 4

The refined eutectic aluminum-silicon alloy has the following composition [% by mass]: silicon 13.9; iron 0.8; titanium 0.4; the remainder being aluminum.

The aluminum-silicon alloy with the above composition at 700°C was placed in an alloy mixing furnace and melted with the Al-Cr and Al-Mn alloy mixtures produced in an induction heating furnace at 850°C and 780°C, respectively. The alloy mixtures were prepared in such a way that, with a chromium to manganese mass ratio of 20:1, the ratio of the sum of the chromium and manganese masses to the sum of the iron and titanium impurities was 0.2:1. The resulting aluminum-silicon melt had the following eutectic composition (mass %): silicon 12.8%; iron 0.8%; titanium 0.4%; chromium 0.23%; manganese 0.01%; the remainder being aluminum. The melt was cooled to 730°C. Solid aluminum was added to the melt to cool it to 590°C, with a mass ratio of aluminum to the cooled melt of 0.07:1. The melt was then filtered at 590°C.

The refined aluminum-silicon melt collected in the metal receiver had the following eutectic composition [mass %]: silicon 11.0; iron 0.30; titanium 0.05; chromium 0.10; manganese 0.005; and the balance aluminum.

Example 5

The refined eutectic aluminum-silicon alloy has the following composition [% (mass)]: silicon 13.2; iron 1.4; titanium 0.7; the balance is aluminum.

The refined aluminum-silicon alloy having the above composition at a temperature of 690° C. is placed in an alloy mixing furnace and melted together with the Al-Cr and Al-Mn alloy mixtures produced in an induction heating furnace at temperatures of 860° C. and 760° C., respectively. The amount of the alloy mixture must be such that, when the mass ratio of chromium to manganese is 10:1, the ratio of the sum of the mass of chromium and manganese to the sum of the mass of iron and titanium impurities is 0.45:1.

The aluminum-silicon melt was mixed for 20 minutes to ensure uniform mixing. The resulting aluminum-silicon melt had the following eutectic composition (mass %): silicon 12.9%; iron 1.4%; titanium 0.7%; chromium 0.86%; manganese 0.085%; the remainder being aluminum. The resulting melt had a temperature of 700°C. To remove non-metallic impurities and cool to 590°C, the melt was held at 590°C for 45 minutes and then filtered.

The refined aluminum-silicon melt collected in the metal receiver had the following eutectic composition [mass %]: silicon 11.2; iron 0.32; titanium 0.05; chromium 0.30; manganese 0.03; the remainder being aluminum.

Example 6

The refined eutectic aluminum-silicon alloy has the following composition [% (mass)]: silicon 13.6; iron 2.0; titanium 1.0; the balance being aluminum.

The refined aluminum-silicon alloy having the above composition at a temperature of 750° C. was placed in an alloy mixing furnace and melted together with the Al-Cr and Al-Mn alloy mixtures produced in an induction heating furnace at temperatures of 840° C. and 880° C., respectively. The alloy mixtures were used in such quantities that, when the mass ratio of chromium to manganese was 0.5:1, the ratio of the sum of the mass of chromium and manganese to the sum of the mass of iron and titanium impurities was 0.69:1.

The aluminum-silicon melt was mixed for 15 minutes to ensure uniform mixing of its components. The resulting aluminum-silicon melt had the following eutectic composition (mass %): silicon 12.2%; iron 2.0%; titanium 1.0%; chromium 0.69%; manganese 1.38%; the remainder being aluminum. The resulting melt had a temperature of 780°C.

To remove non-metallic impurities from the aluminum silicon melt and allow the melt to cool slightly, the melt was held for 30 minutes. Solid aluminum was then added to the melt at a mass ratio of aluminum to cooled melt of 0.06:1, cooling the melt to 625°C. At this temperature, the eutectic aluminum silicon melt was filtered.

The refined aluminum-silicon melt collected in the metal receiver had the following eutectic composition [mass %]: silicon 11.3; iron 0.37; titanium 0.06; chromium 0.24; manganese 0.55; the remainder being aluminum.

Example 7

The refined eutectic aluminum-silicon alloy has the following composition [% (mass)]: silicon 13.9; iron 0.8; titanium 0.4; the remainder is aluminum.

A refined aluminum-silicon alloy with the above-mentioned composition at 680°C was placed in an alloy mixing furnace and melted together with an Al-Cr and Al-Mn alloy mixture produced in an induction heating furnace at 850°C and 840°C, respectively. The alloy mixture was prepared in such quantities that, with a chromium to manganese mass ratio of 0.4:1, the ratio of the sum of the chromium and manganese masses to the sum of the iron and titanium impurities was 0.7:1. The resulting aluminum-silicon melt had the following eutectic composition (mass %): silicon 12.8%; iron 0.8%; titanium 0.4%; chromium 0.24%; manganese 0.60%; the remainder being aluminum. The temperature of the melt was 730°C.

To cool the aluminum silicon melt to 590°C, solid aluminum was added to the melt at a mass ratio of aluminum to the cooled melt of 0.07:1. The melt was then filtered at 590°C.

The refined aluminum-silicon melt collected in the metal receiver had the following eutectic composition [mass %]: silicon 11.2; iron 0.36; titanium 0.08; chromium 0.10; manganese 0.25; the remainder being aluminum.

Example 8

The refined eutectic aluminum-silicon alloy has the following composition [% (mass)]: silicon 13.2; iron 1.4; titanium 0.7; the balance is aluminum.

The refined aluminum-silicon alloy having the above composition at a temperature of 680° C. was placed in an alloy mixing furnace and melted together with the Al-Cr and Al-Mn alloy mixtures produced in an induction heating furnace at temperatures of 860° C. and 880° C., respectively. The alloy mixtures were used in such quantities that, when the mass ratio of chromium to manganese was 0.25:1, the ratio of the sum of the mass of chromium and manganese to the sum of the mass of iron and titanium impurities was 0.9:1.

The aluminum-silicon melt was mixed for 20 minutes to ensure uniform mixing of its components. The resulting aluminum-silicon melt had the following eutectic composition (mass %): silicon 12.0%; iron 1.4%; titanium 0.7%; chromium 0.38%; manganese 1.51%; the remainder being aluminum. The temperature of the aluminum-silicon melt was 710°C. To remove any non-metallic impurities and cool the melt to 660°C, the melt was held for 45 minutes, after which the cooled melt was filtered at 660°C.

The refined aluminum-silicon melt collected in the metal receiver had the following eutectic composition [mass %]: silicon 11.5; iron 0.37; titanium 0.09; chromium 0.14; manganese 0.35; and the balance aluminum.

Example 9

The eutectic aluminum-silicon alloy has the following composition [% (mass)]: silicon 13.6; iron 2.0; titanium 1.0; the remainder is aluminum.

The refined aluminum-silicon alloy having the above composition at a temperature of 730°C was placed in an alloy mixing furnace and melted together with the Al-Cr and Al-Mn alloy mixtures produced in an induction heating furnace at temperatures of 850°C and 920°C, respectively. The amounts of the alloy mixtures were such that, when the mass ratio of chromium to manganese was 0.1:1, the ratio of the sum of the mass of chromium and manganese to the sum of the mass of iron and titanium impurities was 1.1:1.

The aluminum-silicon melt was mixed for 25 minutes to ensure uniform mixing of its components. The resulting aluminum-silicon melt had the following eutectic composition (mass %): silicon 12.2%; iron 2.0%; titanium 1.0%; chromium 0.3%; manganese 3.0%; the remainder being aluminum. The resulting melt had a temperature of 790°C.

In order to remove non-metallic impurities from the aluminum silicon melt and allow the melt to cool slightly, the aluminum silicon melt was held for 45 minutes. This allowed the temperature of the melt to cool to 625° C. Solid aluminum was added to the melt at a mass ratio of aluminum to cooled melt of 0.05:1.

The refined aluminum-silicon melt collected in the metal receiver had the following eutectic composition [mass %]: silicon 11.6; iron 0.39; titanium 0.08; chromium 0.10; manganese 0.65; the remainder being aluminum.

Example 10 (Comparison)

According to the inventor's certificate U.SSR (USSR) No. 1108122, the refined eutectic aluminum-silicon alloy has the following composition [% (mass)]: silicon 13.9; iron 0.8; titanium 0.4; the balance is aluminum.

A refined aluminum-silicon alloy with the above-mentioned composition at 750°C was placed in an alloy mixing furnace and melted together with an Al-Cr and Al-Mn alloy mixture produced in an induction heating furnace at 870°C and 860°C, respectively. The alloy mixture was prepared in such a manner that, with a chromium to manganese mass ratio of 0.5:1, the ratio of the sum of the chromium and manganese masses to the sum of the iron and titanium impurities was 1.2:1. The resulting aluminum-silicon melt had the following eutectic composition (mass %): silicon 12.8%; iron 0.8%; titanium 0.4%; chromium 0.4%; manganese 0.96%; the remainder being aluminum. The melt temperature was 780°C. To cool the aluminum-silicon melt to 615°C, solid aluminum was added to the melt at a mass ratio of aluminum to the cooled melt of 0.08:1. Cooling was stopped when the temperature dropped to 615°C, and the melt was filtered at this temperature.

The refined aluminum-silicon melt collected in the metal receiver had the following eutectic composition [mass %]: silicon 12.6; iron 0.58; titanium 0.13; chromium 0.10; manganese 0.16; the remainder being aluminum.

Example 11 (Comparison)

According to the inventor's certificate USSR (USSR) No. 1108122, the refined eutectic aluminum-silicon alloy has the following composition [% (mass)]: silicon 13.6; iron 2.0; titanium 1.0; the balance is aluminum.

The refined aluminum-silicon alloy having the above composition at a temperature of 730° C. was placed in an alloy mixing furnace and melted together with the Al-Cr and Al-Mn alloy mixtures produced in an induction heating furnace at temperatures of 930° C. and 900° C., respectively. The alloy mixtures were used in such quantities that, when the mass ratio of chromium to manganese was 1:1, the ratio of the sum of the mass of chromium and manganese to the sum of the mass of iron and titanium impurities was 2.0:1.

The aluminum-silicon melt was mixed for 30 minutes to ensure uniform mixing of its components. The resulting aluminum-silicon melt had the following eutectic composition (mass %): silicon 12.2%; iron 2.0%; titanium 1.0%; chromium 3.0%; manganese 3.0%; the remainder being aluminum. The resulting melt temperature was 800°C.

To remove non-metallic impurities from the melt and allow the melt to cool slightly, the aluminum-silicon melt was held for 45 minutes until the melt temperature dropped to 740°C. To cool the eutectic aluminum-silicon melt to 620°C, solid aluminum was added to the melt at a mass ratio of aluminum to cooled melt of 0.06:1. The cooled melt was then filtered at 620°C.

The refined aluminum-silicon melt collected in the metal receiver has the following eutectic composition [mass %]: silicon 12.3; iron 0.70; titanium 0.25; chromium 0.35; manganese 0.40; the remainder being aluminum.

Table 3

Claim method

Nes Parameters

Examples

1    2    3    4

3    4    5    6

1. Filtration to remove iron and titanium impurities 97.5 98.2 97.0 98.8

Output of crystalline aluminum silicon melt, %

2. Aluminum content in filter residue, %    64.3    59.1    66.5    55.2

3. Each unit removed in eutectic aluminum-silicon alloy 0.2 0.65 1.1 0.2

Mass iron and titanium impurities are chromium and manganese

Cumulative mass consumption

4. Eutectic Al-Si alloy iron removal 42.5 75.7 79.0 62.5

Refining degree%

5. Eutectic aluminum silicon alloy with titanium removed 70.0 90.0 87.5 87.5

Refining degree%

6. Elongation of refined eutectic aluminum-silicon alloys 3.3 3.8 3.5 4.0

Elongation, %

Inventor's Certificate

USSRNo1108122

Past known methods

Examples

5    6    7    8    9    10    11

7    8    9    10    11    12    13

98.4    98.0    98.0    97.8    97.2    93.5    88.1

57.0    59.2    59.5    60.5    63.4    72.3    80.3

0.45    0.69    0.7    0.9    1.1    1.2    2.0

77.1    81.5    55.0    73.5    80.5    27.5    65.0

92.85    94.5    80.0    87.1    92.0    67.5    75.0

3.9    3.7    3.7    3.6    3.6    3.0    2.5

Table 3 shows the technical and economic indicators of the process according to the invention and the previously known process, which demonstrates the advantages of the process according to the invention.

Therefore, when the method of the present invention is used to refine a eutectic aluminum-silicon alloy having the following composition [mass %]: silicon 13.9; iron 0.8; titanium 0.4; the remainder being aluminum, it exhibits the following advantages over the conventional methods:

1. The yield of the aluminum silicon melt at the stage of filtering to remove iron and titanium increased from 93.5% to 97.5-98.8%, that is, an increase of 4-5.3% (absolute value).

2. The aluminum content in the filter residue dropped from 72.3% to 55.2-64.3% (absolute value), that is, it dropped by 8-17.1% (absolute value).

3. The cumulative consumption of chromium and manganese is reduced to 1/6 to 1/1.7 of the original amount.

4. The degree of iron removal from the eutectic aluminum-silicon alloy is increased from 27.5% to 42.5-62.5%, that is, an increase of 0.5-1.3 times.

5. The degree of iron removal from eutectic aluminum-silicon alloy refining is increased from 67.4% to 70-87.5%, that is, an increase of 2.5-20% (absolute value).

6. The elongation of the refined eutectic aluminum-silicon alloy increases from 3.0% to 3.3-4.0%, that is, it increases by 0.1-0.3 times.

When the method of the present invention is used to refine a eutectic aluminum-silicon alloy having the following composition [mass %]: silicon 13.6; iron 2.0; titanium 1.0; the remainder being aluminum, it exhibits the following advantages over the conventional methods:

1. The yield of the aluminum silicon melt at the stage of filtering to remove iron and titanium increased from 88.1% to 97.0-98.0%, that is, an increase of 8.9-9.9% (absolute value).

2. The aluminum content in the filter residue decreased from 80.3% to 59.2-66.5%, that is, a decrease of 13.8-21.1% (absolute value).

3. The cumulative consumption of chromium and manganese is reduced to 1/2.9 to 1/1.8 of the original amount.

4. The degree of iron removal from the eutectic aluminum-silicon alloy is increased from 65.0% to 79.0-81.5%, that is, an increase of 0.2-0.25 times.

5. The degree of titanium removal from eutectic aluminum-silicon alloy refining is increased from 75.0% to 90-94%, that is, an increase of 0.2-0.25 times.

6. The elongation of the refined eutectic aluminum-silicon alloy increases from 2.5% to 3.5-3.7%, that is, it increases by 0.4-0.5 times.

In addition to the aforementioned advantages, the present invention's refining method removes iron and titanium in the production of eutectic aluminum-silicon alloys, making it possible to use secondary aluminum and aluminum-silicon alloys doped with iron and titanium, while ensuring the production of high-quality primary aluminum-silicon alloys. This saves primary aluminum and crystalline silicon.

In non-ferrous metallurgy and mechanical engineering, the present invention can be used to refine eutectic aluminum-silicon alloys by removing iron and titanium impurities, the refined alloys having either the properties of a primary alloy or the properties of a secondary alloy.

Claims (3)

1, a kind of method of removing the refining eutectic aluminium-silicon alloy of iron and titanium impurity comprises: al-si eutectic alloys with chromium and manganese are melted in together, the gained melt is cooled to 590～660 ℃, and at the chilled melt of said temperature scope inner filtration.It is characterized in that use chromium and manganese with such quantity, promptly the mass ratio at chromium and manganese be (0.2～1.1): 1 o'clock, make chromium and manganese quality and with the quality of iron and titanium impurity with ratio be (0.2～1.1): 1.

2, according to the method for described removal iron of claim 1 and titanium impurities and refining eutectic aluminium-silicon alloy, it is characterized in that, using with such quantity under the situation of chromium and manganese, make they quality and with the quality of iron and titanium impurity and ratio be (0.2～0.69):, keep the mass ratio of chromium and manganese to equal (0.5～20): 1 at 1 o'clock.

3, according to the method for described removal iron of claim 1 and titanium impurities and refining eutectic aluminium-silicon alloy, it is characterized in that, using with such quantity under the situation of chromium and manganese, make they quality and with the quality of iron and titanium impurity and ratio be (0.7～1.1):, keep the mass ratio of chromium and manganese to equal (0.1～0.4): 1 at 1 o'clock.