CH657290A5 - PROCESS FOR THE PREPARATION OF ALUMINUM ALLOYS FOR THE SEGREGATION OF THEIR COMPONENTS. - Google Patents

Description

The invention relates to a process for the preparation of aluminum alloys with a view to segregating their components, allowing the recovery of used containers such as beverage containers.

In the field of packaging or containers such as used containers for beverages of which one or more components are made of aluminum alloys, there is growing interest and significant research is being carried out to develop methods for recovering the components containing aluminum. Interest was heightened by the need to save resources and by environmental issues. However, to date, the recycling of such materials has been greatly hampered by the absence of an economically advantageous process. For example, attempts to recycle a beverage can whose body is made of an aluminum alloy and the top or lid is constructed of a different aluminum alloy often produces an aluminum-containing melt composition differs from that of the two alloys. The value of this melt is greatly reduced, since it does not lend itself easily to reuse for the manufacture of a body or a can lid without dilutions, purifications, additions of alloying elements or the like. important changes. It can therefore be seen that there is a great need for a process for recycling containers of the type described for example here, in which the various components of the containers are recovered and segregated according to the alloy or according to the type of alloy.

The problem of the segregation of different alloys is recognized in US Pat. No. 3,736,896, in which the separation of the top or covers of aluminum alloys from boxes with molten steel bodies of a small strip of aluminum is described. at the periphery of the box body to create a separation zone allowing the aluminum end to be separated from the cylindrical steel body. In this description, induction heating is used to melt the strip, in which a circular inductor surrounds a bead and is connected to a high frequency power supply. However, this process seems to assume that a used drink can is not crushed and that the end remains perfectly circular. In addition, it does not seem economical to thus separate the ends by fusion, since the ends must be removed individually.

In patent US 4016003, containers having bodies and lids of aluminum alloy are shredded into particles ranging from 25.4 to 38.1 mm, then subjected to the action of temperatures of approximately 371, 1st C to remove paints and

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varnish. In addition, US Pat. No. 4,269,632 indicates that, like the conventional alloys for the ends of the boxes, for example the alloys of the Aluminum Association (AA alloys) 5,182, 5,082 or 5,052, and for the bodies of boxes, for example AA 3004 or AA 3003, have a composition that differs markedly in the manufactured box, the end and the body are essentially inseparable, and that an economical recycling system requires the use of the whole box. US Patent 4,269,632 further notes that recycling the boxes can produce a melt whose composition differs markedly from the compositions of conventional alloys for the end of the box and for the body of the box. In this patent, it is suggested that the end and the body of the box should be made of the same alloy to solve the recycling problem. With regard to the ends and bodies of boxes made in A A 5182 or 3004, it is indicated that normally pure aluminum must be added, whatever the alloy prepared.

Due to these problems of recycling metal containers such as aluminum beverage containers, the components of which consist of different alloys, it would be advantageous to have a method for recovering the containers by segregating their components according to their alloys. or segregation of components according to the type of alloy. Thus, thanks to the segregation of the components before melting, the components can be melted and used in a new manufacture according to the normal processes without, inter alia, costly stages of dilution or purification being necessary.

The invention provides a process for the preparation of aluminum alloys for the segregation of their components which comprises stages consisting in:

(a) heating a raw material containing at least two types of components made up of different aluminum alloys having different melting start temperatures to a temperature sufficient to increase the sensitivity to breakage of at least one of the components to a level sufficient to cause fragmentation of at least one of the components by agitation of the heated raw material;

(b) subjecting the heated raw material to agitation so that at least one of the components fragments; and

(c) cause the fragmented components of the remaining raw material to segregate.

The method according to the invention will be described, by way of example, with reference to the appended drawing, in which:

Figure 1 is an operating diagram illustrating the stages that can be used to classify containers such as used beverage containers.

Figure 2 is a histogram showing the particle size distribution of the material entering and leaving the oven at a temperature of 571.1 ° C.

FIG. 3 is a histogram showing the particle size distribution of the material entering and leaving the oven at a temperature of 582.2 ° C.

FIG. 4 is a histogram showing the particle size distribution of the material entering and leaving the oven at a temperature of 593.3 ° C.

FIG. 5 is a histogram showing the particle size distribution of the material entering and leaving the oven at a temperature of 604.4 ° C.

Figure 6 is an operating diagram illustrating the stages that can be used to classify containers and to remove foreign impurities according to the invention.

FIG. 7 is an operating diagram illustrating the stages that can be used to remove fines in a process for recycling used aluminum containers.

As shown in the operating diagram of FIG. 1, used articles whose aluminum alloy components must be recovered or revalued can consist of containers such as containers for food and drink. The containers to which the process applies are used beverage containers made from two different aluminum alloys. The operating diagram shows that the articles to be recovered can be subjected to a preliminary sorting to eliminate the materials which would contaminate the aluminum alloy to be recovered. For example, it would be desirable to discard glass bottles and steel cans as used for example for food. In addition, it is desirable to remove other materials such as dirt and sand, etc., to reduce the amount of silicon, for example, which may appear in the recovered alloy. The elimination of these materials makes it possible to use the alloy recovered according to the invention without additional purification operation. The preliminary elimination of the steel likely to be present in the form of a container or boxes or the like contributes to keeping the iron in the recovered alloy at a content which does not harm the properties of the recovered Palis bond.

When the material to be recovered is a container for food or drink, it is normally transported in the form of bales and, therefore, before the sorting stage, the bales must normally be removed to remove foreign matter. After the sorting stage, the containers can be subjected to a stripping stage. This can be done by treatment with a solvent or heat treatment. The tarnishing removes coatings such as decorative and protective coatings which may contain elements such as titanium whose high contents are normally not desirable in recovered aluminum alloys. When stripping with a solvent, it is generally desirable to shred or puncture the containers to allow the solvent to flow out. When the coatings are removed by heat treatments, the temperature employed is normally in the range of 315.6 to 537.8 ° C.

In the next stage of the process, in particular when the containers are used beverage containers having bodies made of the Aluminum Association AA 3004 alloy and lids formed from AA 5182 for example, the containers are heated to a tem -35 temperatures at which the AA 5182 cover becomes sensitive to breakage. This temperature has been found to be closely correlated with the melting start temperature or the melting temperature of the grain boundaries of the alloy.

Thus, with regard to the used beverage containers, this is the temperature for the start of melting of the AA 5182. The temperature for the start of melting, or the melting temperature for the grain boundaries, is here the lowest temperature of the melting interval or of the phase melting interval, and it is slightly lower than that at which the alloy becomes sensitive to breakage or exhibits a net increase in susceptibility to breakage, or to which the fragmentation of the alloy can be carried out without the use of a significant force. That is to say, in a state of sensitivity to breakage, fragmentation can be produced by barrel stirring or falling, and the use of forces such as would be obtained with a so hammers or jaw crushers is useless. Forces such as those produced by a hammer mill or a jaw crusher are detrimental in the present process, since they crush the containers, for example, and thus trap the material to be separated. It should be noted that many alloys have 55 different melting temperatures. For example, AA 3004 has a melting start temperature of approximately 629.5 ° C and AA 5182 has a melting start temperature of approximately 580.6 ° C and a phase melting range of 580.6 to 636.7 ° C. However, it should be noted that this range can vary to a great extent depending on the exact position of the alloy used. The beginning of melting or the melting of the grain boundaries of the alloy considerably reduces its resistance and causes breakage. Thus, the covers in A A 5182 can be detached or eliminated from the bodies in AA 3004, because the covers are brought into a state which makes them very sensitive to breakage and fragmentation. In this state, energy supplied for example by barrel agitation can be applied to detach or remove the cover from the body of the box. The separation results mainly from the breaking or fragmentation of the lid forming

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lid parts which not only are smaller than the body of the box, but are generally smaller than a lid.

After the separation stage, a charge or mass is obtained consisting of bodies of boxes and fragmented lids, the bodies of boxes being made of an alloy or of a material different from the fragmented lids and the fragmented lids having a particle size distribution clearly different from that of the box bodies. It is therefore seen that it is not only important to separate the cover from the body of the box but that, in addition, the cover fragments must have a size which differs markedly from that of the body of the box. To obtain a product or alloy which is not adversely contaminated by the alloy with which it is mixed, the charge is subjected to a treatment to effect the classification or the segregation of the fragments. When this aspect of the process is practiced, cover fragments or useful materials are obtained which consist essentially of the same alloys as those separated by segregation of the can bodies.

Although the process has been described generally with regard to the recovery of used cans for beverages, it should be noted that the raw material of the process is not necessarily limited to them. The method allows the classification of aluminum alloys, in particular of shaped alloys in which one of the alloys can be made sensitive to breakage or put in a state such that it can be preferentially fragmented so that a distribution is obtained. particle size differing from that of other alloys. We can thus separate the alloys between them. Thus, for example, the raw material to be recovered can consist of used containers for drinks having bodies made in AA 3004 and lids made in AA 5182. Other alloys which can be used for lids include AA 5082, 5052 and 5042 (Table X). However, other alloys that can be used for food or beverage can bodies include alloys such as AA 3004, AA 3104, AA 5042, and AA 5052 (Table IX) . If such alloys have for example magnesium contents, it is necessary that these bodies of boxes are sufficiently broken or fragmented so that they can be classified with alloys of covers such as AA 5182. It can therefore be seen that the process of the invention not only makes it possible to carry out the elimination and the classification of the lids relative to the bodies of the boxes as indicated here, but also makes it possible to classify the alloys in the bodies of the boxes with the lids, when the alloys have a similar composition and react similarly with regard to the breaking or fragmentation characteristics, as explained here.

In addition, when the containers have bodies and covers made of the same alloy, they can also be recovered by classification. For example, if the body and the lids of the boxes are made of a sheet having the composition 0.1-1.0% by weight of silicon, 0.01-0.9% by weight of iron, 0.05-0 , 4% by weight of copper, 0.4-1.0% by weight of manganese, 1.3-2.5% by weight of magnesium and 0-0.2% by weight of titanium, the rest being l aluminum and accidental impurities, they are classified according to the process of the invention. That is to say that if the raw material to be recovered comprises used containers made of mixed alloys such as alloys AA 3004, 5182 and 5042, as well as the alloy for bodies and lids of boxes above, we may provide that this alloy is classified with the bodies in AA 3004, since there will not be a start of fusion when the temperature is high enough to cause breakage of AA 5182 or AA 5042.

Likewise, if steel containers to which a cover is fixed in AA 5182 are present in the raw material, the covers can be classified according to the method of the invention and the steel bodies recovered with the bodies of boxes in AA 3004. Steel container bodies can be separated from aluminum alloys with which they can be classified by magnetic separation, for example after the lids have been removed. If the containers with steel bodies have lids that break at temperatures within the start of melting range of the AA 3004, then it is necessary to heat the containers to a higher temperature than the AA 5182 for separating the covers from the steel bodies, after which the steel bodies can be removed, for example by magnetic separation.

It emerges from the preceding description that the process of the invention is fairly independent of the raw material containing aluminum to be recovered. Thus, the process can be applied to most types of aluminum alloys and is particularly suitable for the recovery and classification of shaped alloy products as found in used containers. If the waste consists of aluminum alloys used in automobiles, for example alloys AA 6009 and AA 6010 as described in US Pat. No. 4,082,578, which can be used for the manufacture of hoods and doors, etc., it may be desirable to shred these items to obtain a flowable mass. Otherwise, to recover AA 2036 or AA 5182 from used cars, it may be desirable to shred these products and then perform a separation as described here.

Regarding the melting of grain boundaries or the onset of melting of one of the aluminum alloy components to achieve sensitivity to breakage or fragmentation, it should be noted that this is a stage important process and that it should be done with some care. If we take as examples the used beverage cans, it will be noted that the temperature setting is important at this stage. If the temperature is allowed to reach a too high value, there may be a significant melting of the cover at A A 5182, which can lead to losses of aluminum and magnesium by oxidation. Temperatures which produce a notable fusion of the metal should normally be avoided, since they can moreover cause coagulation of the particles with the molten aluminum in the form of a mass which does not flow easily compared to the finer isolated particles. . In addition, the molten aluminum can adhere to the oven and start to form a layer of metal and particles on it, which, of course, impedes the efficiency of the whole operation. Also, the classification of the coagulated mass becomes much more difficult, if not impossible. Finally, during fusion, fines such as sand, glass, dirt and pigments or contaminants such as silicon oxide, titanium oxide and iron oxide tend to become incorporated into the metal. melted, which makes their separation difficult. We therefore see why we must avoid temperatures causing a significant melting of one of the aluminum alloy components.

Likewise, when the temperatures used are too low, the sensitivity to breakage of the lids drops considerably and the resistance to fragmentation increases significantly, so that separation becomes extremely difficult and often segregation cannot be carried out. We therefore see that it is important that the temperature is high enough to separate the cover from the box body. For the covers formed from AA 5182, this temperature corresponds approximately to the start of melting temperature which is approximately 580.6; C. The melting interval for AA 5182 is approximately 580.6 to 636, T C. Thus, if the used beverage containers are heated to 593.3; C, this temperature is well below the melting range of AA 3004 which is approximately 629.5 to 654.4 C, and the lids can be detached or separated without breaking the can bodies.

Regarding the melting of grain boundaries or the beginning of melting, it should be noted that as the sheet with which the lids are made has been rolled to a small thickness, the grains are not well defined. However, it seems that recrystallization occurs when the used beverage containers are heated for example to remove the varnish, which can occur at 454.4 ° C for example. There may therefore be a melting of the grain boundaries.

When the used containers for beverages are heated to around 593.3 ° C or slightly above, it is generally found that the ends in AA 5182 bend or collapse on the body of cans in AA 3004. However, when the containers are shaken

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near this temperature by dropping them from a conveyor belt for example, the lids detach themselves from the can bodies and are divided or fragmented into small particles while the can bodies are relatively unchanged. Sufficient agitation to detach the ends can also be performed in a rotary kiln while the used cans are heated to a temperature in the range of 580.6 to about 623.9 ° C, the preferred range being from 580.6 to 610 , 0 ° C, and typically not more than 604.4 ° C. Sufficient agitation to remove the ends in the rotary kiln may be that which occurs at these temperatures when the boxes are shaken inside the oven. As previously indicated, the forces obtained by hammering or by using a jaw crusher should not be used, since they flatten the boxes or otherwise trap the fragmented ends in the bodies of the boxes. As previously noted, when operating at elevated temperatures in the melting range, too much liquid metal may occur with the corresponding problems. The melting problem becomes particularly acute when the used beverage cans are kept for a relatively long period at elevated temperatures in the melting range. At temperatures in the range of 580.6 to 610.0 ° C, the residence time at this temperature can be between 30 seconds and less than 10 minutes.

In the classification stage, the fragments of AA 5182 can be separated by sieving from whole box bodies or from box bodies which have been shredded. However, it should be noted that other separation methods can be used which all fall within the scope of the invention.

According to another aspect of the invention, as illustrated by FIG. 6, it has been discovered that it is possible to effectively remove, according to the invention, the contaminating materials such as clay, sand, and glass, associated with the used boxes for drinks. You should know that in the field of recycling, contaminants such as clay, sand, etc., can lead to contents of constituents, such as silicon in the recovered metal, which are higher than those accepted in the ranges. composition of the alloy. Thus, in order for the compositions of the alloy to meet the specification, purification, large dilutions or some form of addition of addition elements must be carried out, which clearly affects the economics of recycling. Therefore, not only must the alloys of the different components, for example beverage cans, be separated according to the alloy, but it is also imperative that the incorporation of foreign impurities such as silicon is avoided, as it could produce an alloy that does not meet specifications.

As regards in particular clay or soiling, it should be noted that these materials can produce contamination in the form of calcium, sodium and silicon. Silicon often appears in the form of silicon oxide. Other contaminants include iron, lead and the oxides of aluminum, magnesium and titanium which often result from oxidation during treatment in the furnace. Container coatings are a source of Ti02. The impurities are called foreign impurities, because they are impurities introduced during or after the use of the containers and which normally do not result from the mixture of one alloy with the other. However, foreign impurities are not necessarily limited to these mentioned impurities.

It should be noted that the addition of high purity aluminum to dilute the impurities, such as silicon, also harms the economic performance of recycling. This problem is solved in the invention by the concentration of impurities, such as silicon, so as to allow their elimination from the system.

In the recycling of containers such as used containers for beverage and food, as previously indicated, it is usual to remove by heating the coatings such as decorative and protective coatings. The containers are therefore subjected to the action of temperatures in the range of 315.6 to 357.8 ° C, as previously indicated, to remove these coatings. However, although this treatment is suitable for removing coatings, it has the effect of baking the clay or dirt deposited on the container. Therefore, when remelted waste, clay or cooked dirt is introduced into the melt, which increases the problems of obtaining a useful alloy. It has been found that the breaking of the ends contributes to obtaining smaller particles which remove cooked materials such as clay or dirt from the surface of the containers. It seems that the removal of these materials from the surface is obtained by a cleaning or pickling effect produced by the fine particles of the lids, for example on the bodies of the container. If the heating in the state of fracture sensitivity is carried out in a rotary oven, the pickling of the outside of the larger bodies by the smaller particles is carried out when the oven is rotating. If a conveyor oven is used, abrasion or pickling can be performed while the containers are agitated to break the material susceptible to breakage.

It should be noted that it is not only important to remove the cooked clay or soil from the containers, but also that the cooked materials are in a form to separate them from the materials of the food. This is preferably done by grinding the clay or cooked dirt into fine particles. The clay or cooked dirt must therefore be ground into smaller particles than the smallest particles of all recyclable components. Thus, for example, when the raw material to be recycled consists mainly of containers having bodies made of aluminum alloy and covers or ends made of aluminum alloy, for example bodies made in AA 3004 and covers made in AA 5182 , it is normally preferred that all contaminating material resulting from clay or cooked soiling is separated from the bodies of the containers with the components broken. Then the crushed clay or dirt can be separated from broken components, for example lids. Therefore, the heating and stirring operation reduces the clay or the cooked soils to particles • having a size such that they can be separated from the broken lids. This separation can be carried out by sieving. Thus, in a preferred embodiment, the fine particles of the fired clay can be effectively separated from the lids by the use of a sieve having meshes of less than 0.84 mm, for example, according to a large extent the quantity of foreign impurities to be removed and the corresponding quantity of fine metallic particles present. It should be noted that other means of separation, for example air knife or flotation techniques, can be used.

It should be noted that in the recovery of alloys, the tolerance relating to elements such as silicon can vary depending on the alloy. For example, in alloys with a high silicon content, silicon may not be considered as an impurity. Therefore, what has been explained previously with respect to silicon has been given by way of nonlimiting example. Likewise, in the examples which follow, what concerns silicon is only illustrative.

According to another aspect of the invention, as illustrated in FIG. 7, it has proved to be important to eliminate the metallic fines from the process. When it is desirable to shred aluminum articles, for example used aluminum materials such as used containers, the shredding produces a significant quantity of fine metallic particles which are called fines here. Normally, the production of these fines is not considered to be a significant problem. However, when treating beverage containers to separate the lids from the container bodies, the lids are fragmented as shown here and have a much smaller particle size than the bodies, which allows them to be separated therefrom. However, if the used materials, for example used containers for beverages, are shredded before being treated for separation, the shredding can produce fines which are included in the particle size range of the lids fragments. We can in fact consider that the fines produced by shredding contaminate the fragmented portion. For example, if the wood box5

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bran consists of 75% by weight of AA 3004 and 25% by weight of AA 5182, the fines produced during the shredding of the raw material consisting of such containers can contain 93% by weight of AA 3004 and 7% by weight only of AA 5182. It can therefore be seen that it is very necessary to avoid this type of contamination in the present process. If the fines removal stage is omitted, the fragmented portion of AA 5182 becomes contaminated with the fines from AA 3004 from the can bodies. It has been found that the elimination of fines in the particle size range corresponding to the particle size range of the fragmented portion to be separated from the container body portion produces highly fragmented portions which are essentially free of fines. The fines should be removed after the shredding stage and before the fragmentation stage. One method of removing fines includes the use of sieves.

When the raw material used is made up of beverage containers having, for example, bodies of AA 3004 and covers of AA 5182, after shredding, the fines may constitute 1 to 15% by weight or more of the shredded raw material.

The following example illustrates the contamination that can result from fines produced by shredding. As shown in Table X, the range of compositions for manganese in AA 5182 is 0.20-0.50 by weight. Normally, manufacturers of AA 5182 maintain the manganese concentration in the middle of this range. In the following examples, it is considered that a manganese concentration of 0.38% is desired.

By performing the operation of shredding and then of fragmentation on 100 units of used beverage containers, it has been found in one case that 5 units of fines produced during the shredding stage have a manganese content of 1.10%. They are therefore composed almost entirely of AA 3004. The fragmentation stage produces 20 units of AA 5182 having a manganese content of 0.38%. If these 25 units are not separated but combined, it can be calculated that the manganese content is 0.52%. This requires significant dilution to produce a metal with 0.38% manganese.

In another example, the process forms a shredded product or raw material containing about 9% by weight of fines, the manganese content of this material being 1.05% by weight. If these 9 units of the fragmented portion are combined with the 20 units of AA 5182, the 29 total units have a manganese content of 0.59% by weight. This again requires significant dilution with pure aluminum to produce AA 5182 having a manganese content of 0.38% by weight. We therefore see that it is important to eliminate the fines before mixing them with the fragmented portion.

The balls of food or drink containers mentioned above can be subjected to a shredding type operation so that they are divided. After the shredding operation, the raw material must be sieved to remove the metallic fines for the reasons set out below in detail. As shown in FIG. 7, the fines can be subjected to a stripping stage then recombined with a fraction of the raw material treated according to the invention and finally melted.

As another illustration of the invention, used cans for beverages having bodies in AA 3004 and lids in AA 5182 are treated with a rotary oven. Samples of the material entering the rotary oven and leaving at 4 temperatures are taken. different oven settings of 571.1, 582.2, 593.3 and 604.4 ° C. Samples of incoming material weighing approximately 15 kg are taken. About 6 minutes later, which corresponds to the residence time of the used beverage cans in the oven, samples of outgoing material weighing about 45 kg are taken.

Before being introduced into the ovens, the bales of used beverage cans are treated with a shredder. The shredder in the partial shredding operation of most of the boxes produces a certain amount of fines. In the figures, the particle size analyzes of the incoming and outgoing material are compared for each setting temperature of the oven in order to determine the final degree of fragmentation inside the oven. It manifests itself by a decrease in the weight of the coarse fractions and an increase in the weight of the fine fractions.

The nominal mesh sizes of US Standard series sieves used to fractionate samples are shown in Table I with equivalent Tyler series sieves.

Samples of each particle size fraction are melted and analyzed to follow the proportions of the alloys and also to measure the amount of foreign impurities attached.

The chemical combustion of a sample makes it possible to calculate the relative quantity of AA 3004 and of AA 5182 present. For this, it is considered that AA 3004 contains 1.10% manganese and that AA 5182 contains 0.38% manganese. We therefore see that a melt of used drink cans with a manganese content of 0.92% contains 75% of AA 3004 and 25% of AA 5182. This calculation is carried out for each fraction leaving at the 4 temperatures of oven studied. The quantity of AA 5182 that the calculation reveals to be present constitutes the whole of the hatched part of the histograms of FIGS. 2 to 5.

Figure 2 shows the particle size distribution of the incoming and outgoing material when the oven temperature is set at 571.1 ° C. The distribution of AA 5182 in the outgoing material is also shown. The temperature recorded during the sampling period is between 554.4 and 571.1 ° C. The main characteristic of the figure is that there is very little difference in the particle size distribution of the incoming and outgoing material. It is also seen that the mixture of AA 5182 and AA 3004 in the coarsest outgoing fractions corresponds to respective proportions of approximately 25% and 75%, which indicates that the fragmentation of the lids does not seem to occur at this temperature.

Table II shows the spectographic analysis of the metal of each particle size fraction of the incoming and outgoing material. Also, the incoming material and the outgoing material for a given particle size fraction appear very similar, with the exception of magnesium.

It therefore appears that there is a variant of the composition depending on the particle size fraction, which suggests that the grinding stage, before stripping, produces more body fines than end fines. The finest fractions have high manganese contents and reduced magnesium contents compared to the coarser fractions. These finer fractions therefore appear richer in AA 3004 than the coarser fractions. The body of the boxes being thinner and constituting a larger portion of the surface of the box than the end, it can be expected that, during the shredding of used boxes for beverages, the body produces more fines than the end. The decrease in magnesium content as the grain size decreases may also reflect the increased oxidation of magnesium that occurs during the melting of the finer grain material for analysis. The incoming and outgoing material passing through the 2.00 mm mesh opening screen does not contain enough metallic material to melt and produce a sample suitable for spectrographic analysis.

The values corresponding to samples taken while the oven is set at temperatures of 582.2 ° C and 593.3 ° C appear respectively in Figures 3 and 4 and Tables III and IV. These samples show that the AA 5182 covers are fragmented inside the rotary kiln. More particularly, the quantity of material present in the fine sieving fractions in the outgoing material is increased compared to the incoming material; and these fines have compositions which show an enrichment in AA 5182. This tendency is more pronounced at 593.3 ° C than at 582.2 ° C.

The samples taken at 604.4 ° C establish the most certain definitive proof of the fragmentation of AA 5182 inside the oven. The two coarsest fractions show a significant reduction in weight after passing through the oven and the four finest fractions all have a significant increase in weight (Figure 5). The compositions of the fractions (table V) mon5

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trent that the coarsest fractions are almost composed of AA 3004 of commercial quality and that the finer material is almost composed of AA 5182 of commercial quality. If we compare the values of the experiments carried out at 571.1 ° C and 604.4 ° C, we see a migration of AA 5182 from coarse fractions to fine fractions.

Table V shows that the metal of the fraction passing through a sieve of 2.00 mm mesh size of the sample treated at 604.4 ° C contains 0.50% of silicon. This is very important, as this fraction represents about 30% of the AA 5182 in the system. This material was subjected to additional screening to determine whether it was possible to screen out foreign contaminants containing silicon. The results appear in Table VI. The foreign silicon apparently migrates in the fractions passing through the sieve of 0.84 mm mesh opening. The fraction passing through a sieve of 0.71 mm mesh size contains such a large amount of non-metallic material that it cannot be melted to prepare a sample for spectrographic analysis. Visual examination reveals significant amounts of glass and sand. The chemical analysis of the material passing through a sieve of 0.71 mm mesh opening is shown in Table VII. This fraction contains only about 56% metallic aluminum. The sand and glass content is about 23% by weight and the foreign iron content is about 1.7% by weight. The rejection of all the material passing through the sieve of 0.84 mm mesh opening to minimize the fixation of silicon and foreign iron contributes 2.2% to the losses of the system. However, this material contributes a lot to the formation of dirt and must be removed before fusion for this reason.

It should be noted that some alloys tolerate foreign impurities better than others, such as silicon. For example, with regard to AA 3004 and AA 5182, it will be noted that the maximum content is 0.30% by weight for AA 3004 and 0.20% by weight for AA 5182. In addition, Table V and Figure 5 show that, as a result of foreign impurities, silicon can exceed these contents. If the weight percentage and the silicon content of each fraction are taken into account, the amount of silicon can be calculated in the fragmented component. For example, in the example presented by way of illustration, the amount of silicon in AA 5182 which appears in Table V (without removal of foreign impurities) is 0.30% by weight of silicon, which is much higher at the limit of 0.20% by weight for AA 5182. However, after removal of foreign impurities, for example after removal of the material passing through the sieve with 0.84 mm mesh opening (Table VI) of the fraction of AA 5182, AA 5182 is obtained having only a silicon content of 0.71% by weight. It should be noted that an additional 50% of silicon-free material would be required to reduce the silicon content from 0.30% by weight to 0.20% by weight. In addition, it should be noted that the fractions used and indicated in the tables are only for illustrative purposes, because different alloys can tolerate different levels of impurities.

In a test using whole cans, the used containers for beverages were treated in an experimental apparatus at about 598.9 ° C. The fragmented ends constituted 25.3% of the weight of the spilled cans. Bodies represented 74.7%. This suggests that the efficiency of the alloy separation was almost 100%. The two portions were melted and analyzed. The spectrographic results are shown in Table VIII and can be compared to the values of AA 5182 and AA 3004 (see Tables IX and X). These analyzes confirm that 100% separation of the two alloys is possible when the starting material consists of 20 whole boxes.

Board /

Sieve used to split samples

Sieve

Opening

Mesh series sieve (mm)

Tyler series

2 inch

50.8

2 inch

1 inch

25.4

1 inch

0.5 inch

12.7

0.5 inch

0.265 inch

6.73

3 mesh

# 4

4.76

4 mesh

# 7

2.83

7 mesh

# 10

2.00

9 mesh

N ° 14

1.41

12 mesh

N ° 18

1.00

16 mesh

# 20

0.84

20 mesh

N ° 25

0.71

24 mesh

Table II

Chemical analyzes of incoming material (EN) and outgoing material (SOR) for each particle size fraction

Oven setting temperature: 571.1 ° C

Mesh opening

Yes

Fe

Cu

Mn

Mg

+2 "

IN

0.17

0.41

0.11

0.90

1.19

SOR

0.17

0.41

0.11

0.91

1.23

-2 "+ l"

IN

0.17

0.41

0.11

0.92

1.22

SOR

0.18

0.40

0.10

0.86

1.20

- 1 "+1/2"

IN

0.16

0.38

0.10

0.85

1.72

SOR

0.16

0.39

0.11

0.86

1.02

- 1/2 "+0.265"

IN

0.17

0.41

0.11

0.91

1.19

SOR

0.17

0.40

0.11

0.92

0.78

-0.265 "+4

IN

0.21

0.41

0.12

1.00

0.73

SOR

0.24

0.42

0.12

1.01

0.78

657,290

8

Table // (continued)

Mesh opening

Yes

Fe

Cu

Mn

Mg

-4 + 7

IN

0.37

0.45

0.14

1.06

0.35

SOR

0.26

0.45

0.13

1.05

0.68

-7 + 10

IN

0.24

0.44

0.13

1.06

0.26

SOR

0.24

0.48

0.13

1.03

0.54

-10 *

IN

-

-

-

-

-

SOR

-

-

-

-

* Insufficient metal content for quantitative analysis.

Table III

Chemical analyzes of the particle size fractions leaving the oven set at a temperature of 582.2 C

(mm)

Mesh opening

Yes

Fe

Cu

Mn

Mg

50.8 (+)

+2 "

0.17

0.39

0.11

0.95

0.96

50.8-25.4

—2 "+ l"

0.18

0.39

0.10

0.91

1.05

25.4-12.7

—1- + 1/2 "

0.17

0.39

0.11

0.90

1.10

12.7-6.37

-1/2 "+0.265"

0.17

0.39

0.10

0.87

1.03

6.37-4.76

—0.265 "+4

0.22

0.38

0.10

0.83

1.63

4.76-2.83

-4 + 7

0.18

0.36

0.09

0.73

2.08

2.83-2.00

-7 + 10

0.17

0.32

0.07

0.60

2.70

2.00 (-)

-10

0.23

0.32

0.11

0.55

1.54

Table IV

Chemical analyzes of the particle size fractions leaving the oven set at a temperature of 593.3 "C

(mm)

Mesh opening

Yes

Fe

Cu

Mn

Mg

50.8 (+)

+2 "

0.17

0.41

0.12

0.94

0.48

50.8-25.4

—2 "+1"

0.18

0.42

0.12

0.97

0.66

25.4-12.7

- 1 "+1/2"

0.19

0.42

0.12

0.98

0.64

12.7-6.37

- 1/2 "+0.265"

0.18

0.41

0.12

0.94

0.56

6.37-4.76

-0.265 "+4

0.17

0.35

0.09

0.73

1.36

4.76-2.83

-4 + 7

0.15

0.30

0.19

0.56

2.57

2.83-2.00

-7 + 10

0.15

0.29

0.06

0.46

2.15

2.00 (-)

-10 *

-

-

-

-

-

Table V

Chemical analyzes of the particle size fractions leaving the oven set at a temperature of 604.6: C

(mm)

Mesh opening

Yes

Fe

Cu

Mn

Mg

50.8 (+)

+2 "

0.19

0.44

0.13

1.05

0.58

50.8-25.4

_2 "+ l"

0.18

0.43

0.12

1.02

0.66

25.4-12.7

- 1 "+1 / 2"

0.18

0.44

0.12

1.03

0.67

12.7-6.37

- 1/2 "+0.265"

0.18

0.43

0.12

1.02

0.57

6.37-4.76

—0.265 "-e-4

0.21

0.37

0.10

0.82

1.61

4.76-2.83

-4 + 7

0.17

0.30

0.07

0.52

2.97

2.83-2.00

-7 + 10

0.18

0.25

0.05

0.36

3.43

2.00 (-)

-10 *

0.50

0.29

0.07

0.36

3.35

9

657,290

Table VI

Chemical analyzes of the fractions resulting from the additional fractionation of the material passing through a sieve with a 2.00 mm mesh opening leaving the oven set at a temperature of 604 ° C.

(mm)

Mesh opening

% in weight

Yes

Fe

Cu

Mn

Mg

2.00-1.41

-10 + 14

2.6

0.15

0.27

0.04

0.38

3.67

1.41-1.00

-14 + 18

1.9

0.16

0.28

0.04

0.38

3.82

1.00-0.84

-18 + 20

0.5

0.21

0.26

0.04

0.35

3.64

0.84-0.71

-20 + 25

0.4

0.35

0.21

0.05

0.33

3.74

0.71 (-)

-25 *

1.8

-

- •

-

-

-

* Insufficient metal content for qualitative analysis Table VII

Analysis of the material passing through the sieve of 0.71 mm of mesh opening leaving the oven set at 604.4 ° C of mesh opening

% aluminum by evolution of hydrogen

56.2%

Chemical analysis: Al

56.7%

Fe

1.74%

Yes

10.8%

(calculated) Si02

23.1%

% of magnetic material

1.87%

X-ray diffraction

> 10%

Aluminum Quartz

> 10%

MgO

<10%

Not identified

<10%

Table VIII

Chemical analyzes of the experiment with whole boxes having bodies in A A 3004 and ends in A A 5182

20

Fragments of the extremities

Body

Yes

0.10

0.19

Fe

0.25

0.40

Cu

0.03

0.14

Mn

0.36

1.09

Mg

3.69

0.7

Cr

0.02

0.01

Or

0.00

0.00

Zn

0.02

0.04

Ti

0.01

0.02

Table IX

Alloy

Silicon

Iron

Copper

Manganese

Magnesium

Chromium

Zinc

Titanium

Other

Each

Total

AA 3003

0.6

0.7

0.05-0.2

1.0-1.5

0.10

0.05

0.15

AA 3004

0.30

0.70

0.25

1.0-1.5

0.8-1.3

-

0.25

0.05

0.15

AA 3104

0.6

0.8

0.05-0.25

0.8-1.4

0.1-1.3

-

0.25

0.10

0.05

0.15

Note: In Table IX, the balance is aluminum, and the composition is in maximum weight%, except when expressed by a range.

Paintings

Alloy

Silicon

Iron

Copper

Manganese

Magnesium

Chromium

Zinc

Titanium

Other

Each

Total

AA 5182

0.20

0.35

0.15

0.20-0.50

4.0-5.0

0.10

0.25

0.10

0.05

0.15

AA 5082

0.02

0.35

0.15

0.15

4.0-5.0

0.15

0.25

0.10

0.05

0.15

AA 5052

0.45

If + Fe

0.10

0.10

2.2-2.8

0.15-0.35

0.10

-

0.05

0.15

AA 5042

0.20

0.35

0.15

0.20-0.50

3.0-4.0

0.10

0.25

0.10

0.05

0.15

Note: In Table X, the balance is aluminum, and the composition is in maximum weight%, except when it is expressed by a range.

R

5 sheets of drawings

Claims (10)

657,290 1. Process for the preparation of aluminum alloys with a view to segregating their components, characterized in that it consists of: (a) heating a raw material containing at least two types of components comprising different aluminum alloys having different melting start temperatures, at a temperature sufficient to increase the sensitivity to breakage of at least one of the components to a level sufficient to cause fragmentation of at least one of the components by agitation of the heated raw material; (b) subjecting the heated raw material to agitation to cause the fragmentation of at least one of the components; and (c) segregate the fragmented components of the remaining raw material. 2. Method according to claim 1, characterized in that, in stage (a), the raw material is heated to a temperature high enough to cause the onset of melting of the component having the lowest melting start temperature and, in stage (b), the heated raw material is subjected to sufficient agitation for said component having the lowest melting start temperature to fragment. 2 3. Method according to claim 1 or 2, characterized in that the raw material comprises ends of aluminum containers and bodies of aluminum containers, the ends and bodies being made of different aluminum alloys, so that the ends are separated from the bodies and recovered. 4. Method according to one of the preceding claims, characterized in that it comprises the use of a raw material consisting of used containers for food and drink and, preferably, the sorting of the raw material before heating to eliminate contaminating materials including glass and steel containers and, preferably also, the treatment of the raw material to remove varnishes and decorative and protective coatings. 5. Method according to one of the preceding claims, characterized in that the raw material is subjected to barrel agitation to cause the fragmentation of the component having the lowest melting start temperature. 6. Method according to one of the preceding claims, characterized in that the raw material contains one or more types of containers having bodies made of an aluminum alloy, said containers having ends made of the same or another aluminum alloy and, if desired, in that the raw material additionally contains containers having bodies and covers made of sheet metal having the following composition: 0.1-1.0% by weight of silicon , 0.01-0.9% by weight of iron, 0.05-0.4% by weight of copper, 0.4 to 1.0% by weight of manganese, 1.3 to 2.5% by weight of magnesium and 0-0.2% by weight of titanium, the rest being aluminum and impurities. 7. Method according to one of the preceding claims, characterized in that the heating is adjusted in stage (a) to avoid melting of the component having the lowest melting start temperature. 8. Method according to one of the preceding claims, characterized in that the raw material is heated to a temperature in the range of; A) 482.2 at 623.9 ° C; B) 537.8 at 623.9 ° C, preferably for 15 seconds to several minutes; C) 580.6 to 623.9 ° C; D) 580.6 to 604.4 C, preferably for 30 seconds to 15 minutes; or E) 580.6 to 648.9 "C. 9. Method according to one of the preceding claims, characterized in that, before stage (a), the raw material is mixed with foreign impurities, in said stage (b), the heated raw material is agitated enough so that said component having the lowest melting start temperature fragments and so that said fragmented component removes foreign impurities from the unfragmented raw material by pickling and, in stage (c), the fragmented components and foreign impurities undergo segregation compared to the unfragmented raw material, then the fragmented components are separated from the foreign impurities, preferably by sieving, the foreign impurities consisting of calcium, sodium, silicon, iron, lead and aluminum as well as their oxides, and a source of foreign impurities which can be dirt or clay, which is ground to a lower granulometry than that of most of the components. recyclable. 10. Method according to one of the preceding claims, characterized in that it comprises the shredding of the raw material producing fines in the shredded raw material and in that, before the heating stage (a), the shredded raw material at least the fines having sizes included in the particle size range of the fragmented components which are produced in stage (b), the fines being preferably removed by sieving.