TR201704220A2 - Production method of scandium metal and Al-Sc alloys by electrolysis from scandium salt mixtures formed by adding CaCl2 and / or MgCl2 compounds to scF3 compound obtained from scandium compound in the form of (NH4) 2NaScF6 - Google Patents

Abstract

The invention relates to a mixture of scandium salt mixtures which are initially formed by reacting the scandium compound in the form of (NH4) 2NaScF6 with HCl in an aqueous medium and removing (Na4) and Na together with Cl to reduce the melting temperature of the ScF3 compound. The present invention relates to a process for producing scandium metal, either pure or alloyed, by molten salt electrolysis or electrolysis. Figures 1 and 2

Description

DESCRIPTION The ScF3 compound obtained from the scandium compound in the form of (NH4)2NaScFs, CaClz from scandium salt mixtures formed by the addition of velor or MgClz compounds Production method of scandium metal and AI-Sc alloys by electrolysis method Technical Area The invention shows that scandium compound in the form of (NH4)2NaScFe is mixed with HCl in an aqueous medium. obtained by reacting and removing (NH4) and Na together with CI. By adding CaCl2 and or MgCl2 salt to lower the melting temperature of the SCF3 compound molten salt from the ScFs-CaCl2, Sch-MgCl2 or ScF3-CaCl2-MgCl2 salt mixtures formed Scandium, pure or alloy, by electrolysis or electrolysis It is related to the metal production method.

State of the Art Scandium metal is one of the transition metals and rare metals in group BB of the periodic table. It is one of the elements that are called as earth elements and rarely enriched in nature. is one. The very rarity of ores that can be economically exploited in nature, It has been a major obstacle to the production of metal and its use in various sectors. to this day up to uranium, tin, iron, tungsten, tantalum, zirconium, titanium and other rare earths trace elements in more than 100 minerals in ores where the elements are economically processed. It has been determined that these metals are found in amounts and they are used as a by-product during the production of these metals. has been achieved. In addition to this, recently in the iateritic type nickel-cobalt ores The presence of a significant amount of scandium element, during the exploitation of these resources It has brought forward the potential of obtaining scandium as a by-product, and this Numerous studies have been started recently on this subject. One of these studies is “Meta Nickel Publication number TR201308682, which belongs to Kobalt Madencilik Sanayi ve Ticaret Anonim Şirketi. acid Ingestion under metallized solution of scandium and purification It is a patent application titled 'recovery from sediments'. The other is; 'Meta Nickel Cobalt' again "Containing nickel, cobalt and scandium Recovery of scandium and its derivatives from an internal solution loaded with metals' is the reference. The references in question refer to those found in iateritic type nickel-cobalt ores. relates to the recovery of scandium.

Another one of them is; Publication number U83111467 is a reference to U8. Aforementioned In the application, pure NaF, 80F3 and 80203 salts are required for the electrolysis process. required. First of all, NaF and 80F3 salts are mixed and melted at 800 cC, then The 80203 salt is dissolved in this solution.

One of the most important usage areas of scandium element; high strength, corrosion In applications requiring strength and weldability, 0.2%- They are aluminum-scandium alloys obtained by adding 0.8 scandium. This Alloys are usually made of pure scandium metal or master containing 1-20% scandium. It is obtained by adding alloys to molten aluminum metal. One of the methods used to obtain 8af scandium metal is the pure 80203 compound. metallothermic reduction at high temperature with calcium metal in the gas phase. is based on. However, 80203 is an extremely stable compound during reduction. Since the reduction process is not complete, some scandium metal is lost in the form of Ca80204.

Another method used in the production of pure scandium metal is that the 80203 compound calcium by conversion to the relatively less stable 80F3 form with HF gas at high temperature. It is the process of metallothermic reduction with metal at high temperature. However, 80203 The HF gas used during the conversion of the compound to the 80F3 form is environmentally harmful. It is a highly harmful and corrosive compound, making the process extremely difficult technically.

At the end of the reaction, the CaF2 compound is formed together with the scandium metal. The problem of separating scandium from this compound arises. Moreover; applied tantalum crucibles where the reduction process takes place and during the reaction Impurity problems occur due to the calcium metal used. The vacuum distillation method used to remove impurities is additional to the process. brings costs. In order to eliminate these mentioned problems; pure 80203 or 80F3 Reduction of the compound with calcium metal in the presence of aluminum metal proposed, so that instead of obtaining pure scandium metal, aluminum alloy of scandium gain is suggested. Scandium, which is reduced to a metallic state during this process The reduction process is further enhanced by the dissolution of the metal in the molten aluminum metal. It has been argued that it becomes easy and efficient.

However; During the reduction process at high temperatures, tantalum and calcium impurity problems caused by the metal of the pure 80203 compound as the starting compound. The formation of the AI4Ca phase in the processes where it is used, the pure 80F3 compound as the starting compound. In the processes where it is used, the necessity of using HF gas still remains during these processes. stands before us as technical problems that need to be resolved.

Metallothermic reduction with calcium metal at high temperatures molten salt electrolysis as an alternative to get rid of the problems in It has been `suggested' that scandium metal can be obtained by the method [1]. molten salt the basic principle of the method; a suitable salt of the compound to which the desired metal is bound. To ensure that it is dissolved by dissociating it into ions at high temperature in the mixture, at this time also selectively with electric current applied to the molten salt mixture at high temperature. is to ensure that the desired element is reduced and collected at the cathode. During this operation salts that can be used are fluorine, chlorine, bromine and iodide salts, of which the most common salts are the preferred ones have been the fluorine and chloride salts and mixtures of these salts [2]. Chloride and When molten salts containing fluorine are compared among themselves, salts containing fluoride; high more stable at temperatures, no moisture catching problem seen in chlorides It is more preferred due to its (not being hygroscopic) and high current efficiency. As a result, due to the above-mentioned negativities and existing solutions Due to its inadequacy about the scandium metal production method, there is no technical knowledge in the field. development is necessary.

Purpose of the Invention The present invention satisfies the above-mentioned requirements, eliminates all disadvantages. from the scandium compound in the form of (NH4)2NaScFe, which removes formed by the addition of CaCl2 and/or MgCl2 compounds to the obtained ScFs compound, Scandium metal and AI-Sc from scandium salt mixtures by electrolysis method It is related to the production method of alloys.

The 'primary object' of the invention is the production of pure scandium metal, scandium at a rate of 0.2% to 0.8% direct production of aluminum-scandium alloys containing 1-20% scandium is the production of aluminum-scandium master alloys containing

An aim of the invention is; The technical problems brought by the metallothermic reduction method It is the production of scandium metal by the molten salt method to eliminate it. this much to provide; is to obtain salts containing fluoride-chloride.

It is an object of the invention to obtain (NH4)2NaScFe> starting raw material without calcination. It is reacted with HCl in aqueous medium, and the (NH4) and Na in its body are combined with CI. With the addition of CaCl2 and/or MgCl2 to the SCF3 compound obtained by the removal of Sch-CaCl2, Sch-MgClz or ScFs-CaCl2-MgCl2 salt for use in the method It is obtained from the mixtures.

Another object of the invention is the high melting point ScFa (into, It is the addition of CaCl2 and/or MgCl2 to reduce the melting temperature. This is because; The salts used during the molten salt electrolysis are in the molten phase during the process. their presence is necessary. Therefore, the melting temperature of the obtained salt mixture it should be relatively low. Thus, 1 part by weight of 8ch and 15 parts by weight of CaCl2 and/or MgCl2 salt mixture heated and melted at a relatively low temperature of ~8OO cC has been detected.

A similar object of the invention is to prevent mixing of multiple high purity salts.

To fulfill the above-described purposes, the pure scandium metal production method and its feature is; a) Obtaining the ScFs compound from the scandium compound in the form of (NH4)2NaScFe, b) CaCl2 and/or CaCl2 to the obtained ScFs compound to reduce the melting temperature. Obtaining scandium salt mixtures as a result of adding MgCl2, c) the obtained scandium salt mixtures are processed by molten salt electrolysis method. subjected to electrolysis, It contains transaction steps.

The structural and characteristic features of the invention and all its advantages are given in the following figures and More clearly thanks to the detailed explanation with references to the figures. will be understood and therefore the assessment should also take into account these figures and detailed explanation. must be made by taking

Figures to Help Understand the Invention Figure 1: View of the cell system used to obtain pure scandium metal Figure 2: View of the cell system used to obtain aluminum-scandium alloy Figure 3: Obtained after reaction of (NH4)2NaScFe with 4 M HCl at 95 cC for 2 hours Sch's XRD graph Figure 4: XRD graph of AI-Sc alloy obtained as a result of electrolysis Figure 5: Optical microscope image of AI-Sc alloy obtained as a result of electrolysis (X190 magnification) Figure 6: Electron microscope image of AI-Sc alloy obtained as a result of electrolysis (x1300 magnification) and measurement of micro-hardness values of Al and Algsc phases Drawings do not necessarily need to be scaled and are necessary to understand the present invention. details may be neglected. Moreover, at least largely Elements that are identical, or at least substantially identical, are assigned the same number. is shown.

Detailed Description of the Invention In this detailed description, the subject of the invention is obtained from scandium compound in the form of (NH4)2NaScFe. Scandium, formed by the addition of CaCl2 and/or MgCl2 compounds to the SCF3 compound obtained of scandium metal and Al-Sc alloys from salt mixtures by electrolysis method. preferred embodiments of the production method only serve for a better understanding of the subject. It is disclosed as intended and without any limiting effect.

The invention deals with the production method of scandium metal in pure or alloy form. Meet The scandium production method in question consists of three stages. First stage; as a start Scandium compound in the form of (NH4)2NaScF6 is reacted with HCl in aqueous medium, It is to obtain Sch compound by removing it together with (NH4) and Naiun CI.

In the second stage; melting into ScF3 (1552 C), which has a high melting temperature. Sch-CaCIz, ScFs- MgCl2 or ScFs-CaCl2-MgCl2 scandium salt mixtures are obtained. The reason for adding CaCl2 and/or MgCl2 to ScF (; during molten salt electrolysis The salts used must be present in the molten phase during the process. Therefore, It is desired that the melting temperature of the obtained salt mixture be relatively low. Thus by weight A mixture of 1 part ScFa and 15 parts by weight CaCl2 and/or MgCl2 salt is heated and at ~8OO °C. It has been determined that it is in a molten state at a relatively low temperature. The third stage is; ScFa- CaCl2, ScFa-MgCl2 or ScFa-CaCl2-MgCl2 fluoride-chloride salt mixtures, pure scandium To obtain the metal, molten salt is used in the electrolysis method.

Scandium compound in the form of the subject of the invention (NH4)2NaScF6 with 2-6 M HCl solution (preferably is inserted.

Figure 1 shows the cell system used to obtain pure scandium metal. Pure To obtain scandium metal, CaCl2 and/or ScF3 compound obtained in the first step By adding MgCl2 compounds, Sch-CaCl2, Sch-MgClg or ScF3-CaCl2-MgCl2 scandium salt The mixture is fed into the electrolysis cell.

Presence of salts used during molten salt electrolysis in the molten phase during the process required. For this reason, it is desirable that the melting temperature of the salt mixture obtained is relatively low.

A molten mixture of fluoride-chlorinated salt at a relatively low temperature, such as 800 cC. has been detected. Therefore, during electrolysis, the electrolysis temperature, salt It should be increased above 800 cC where the mixture will be in molten state.

Above these temperatures, Na, Ca, Mg, Sc, F and Cl elements are generally Na*, It exists in the forms of Ca”, Mg”, Sc+3, F' and CI_. Therefore, this molten mixture When an electric current is given through the anode-cathode at a certain potential, positively charged Na*, Ca”, Mg”, Sc*3 ions will be affected by the cathode, and negatively charged F_ and CI” ions will be affected by the anode.

Depending on the applied potential and the relative stability of these ions, the anode and cathode Electrochemical reduction and oxidation reactions will be observed in the regions.

The preferred temperature is the salt mixture of Sch-CaCl2, ScFa-MgCl2 or ScFs-CaClg-MgClz. Depending on its composition, it should be chosen 10-15 °C above the temperature at which it passes into the liquid phase.

Electric current is given to the circuit in such a way that it operates at a potential difference of 2-8 volts.

The current density to be applied to the circuit is fixed, preferably 0.5-1.0 A/cm2. trying to be caught. Thanks to the relatively low potential applied, Na*, Ca2+ and Mg2+ ions are prevented from reacting and only Sc3+ ions are reduced at the cathode. It is ensured that it is collected in metallic form at the base of the electrolysis cell. Therefore, turn on Adjusting the potential difference to be applied so that it does not exceed 3 volts Na, Ca and Mg It will eliminate the contamination problem. Oxidation reactions taking place at the anode As a result, the F' and CI' ions react with the graphic anode to produce various fluoro-chloro carbon gases. will leave the cell. These gases emitted at the anode are undesirable for the environment. The resulting gases can then be collected and rendered harmless. In this study, these gases does not include disposal. If it is desired to dispose of these gases more easily, graphite By using more stable anode materials that will not interact with fluorine-chlorine instead of the anode. Only fluorine and chlorine gases can be output at the anode. These gases, which come out later, are gas collection. It can be converted into more stable and harmless corrosion-chloride compounds through the unit. On In cases where fluorine-chlorine gas is not desired to be discharged after the reduction reactions, 80203 compound, with a weight ratio not exceeding 10% in the total salt bath by adding this compound to dissolve in the molten salt phase as Sc+3 and O'2 ions. can be provided. O'2 ions have lower potentials compared to F' and Cl' ions. By controlling the potential difference applied to the circuit due to its oxidation, F' and CI' ions can be prevented from reacting. In this way, the carbon and oxygen in the graphite anode carbon monoxide and carbon dioxide, which are easier to dispose of environmentally after reactions gases can be released. Alternatively, instead of graphite at the anode, it can react with oxygen. By using more stable anode materials that do not penetrate, the anode is environmentally problematic. It is possible to obtain oxygen gas that does not cause oxygen. Oxidation at anode and cathode and When the reduction reactions are over, the Sc+3 ions in the solution are released from the salt mixture. It is obtained by separating it and collecting it as pure scandium metal at the base of the electrolysis cell.

If the product desired to be obtained by the molten salt method contains 0,2-0,8 % scandium. aluminum-scandium alloy or aluminum-containing 1-20% scandium scandium master alloy; cell bottom before reaction 'as shown in Figure 2 pure aluminum metal is added. Then it is obtained after calcination process on AI metal. A salt mixture of Sch-CaCl2, Sch-MgCl2 or Sch-CaCl2-MgCl2 is added.

Then, the cell aluminum and fluoride-chloride salt mixture can be found in molten state. It is increased above the temperature (preferably, both phases are provided to become liquid.

When the melting process is completed, there is no liquid at the base of the electrolysis cell due to density differences. aluminum, on the liquid aluminum, there is a molten fluoride-chloride salt mixture.

Electric current can be supplied to the circuit in such a way that it operates at a potential difference of 2-8 volts.

Thanks to the relatively low potential applied, preferably not exceeding 3 volts, Na*, Ca”, Mg2+ ions are prevented from reacting and only 803+ ions are at the cathode. in liquid aluminum, which is molten at the base of the electrolysis cell by reducing dissolution is achieved. At the anode, as a result of the oxidation reactions, F' and Cl' ions react with the graphic anode and leave the cell as various fluoro-chloro carbon gases. will. Since these gases emitted at the anode are undesirable for the environment, the emitted gases are more It can then be collected and rendered harmless. Easier disposal of these gases If desired, more stable anode materials that will not interact with ror and chlorine instead of graphite anode Only fluorine and chlorine gas can be output at the anode. These gases released later, It can be converted into more stable and harmless fluoride-chloride compounds through the gas collection unit.

After the reduction reactions in the circuit, fluorine and chlorine gas output is not desired. In such cases, 80203 salt mixture shall not exceed 10% by weight in total. or as 80*3 and 02 ions of scandium oxide by adding Al2O3 compounds, dissolution of aluminum oxide as Al+3 and O'2 ions in the molten salt phase is provided. The 0'2 ions have lower potentials than the F' and CI' ions. By controlling the potential difference applied to the circuit due to its oxidation, F' and CI' ions can be prevented from reacting. In this way, the carbon and oxygen in the graphite anode carbon monoxide and carbon dioxide, which are easier to dispose of environmentally after reactions gases can be released. Alternatively, the graphite at the anode can be reacted with oxygen instead of the anode. cause environmental problems at the anode by using more stable anode materials that do not Oxygen gas that does not open can be obtained. Potential difference of 2-8 volts applied to the cell Electrolysis by reducing together Sc+3 and AI+3 ions in the molten salt phase between dissolves in the aluminum phase, which is molten at the base of the cell. In this way Scandium for the desired process time by applying an electric current at a potential of 2-8 volts to the cell. if it is maintained up to its concentration; Aluminum-containing 0.2-0.8% scandium Scandium alloy or containing 1-20% scandium with longer electrolysis times aluminum-scandium master alloys can be obtained. Electrolysis after electrolysis aluminum-scandium alloy, which is in liquid form at the base of the cell, is also in liquid form. Aluminum-scandium alloy is obtained by separating the molten fluoride-chloride salt phase.

REFERENCES . Xiao Y. Yan and D.J. Fray, Molten salt electrolysis for sustainable metals extraction and materials processing - A review, in Electrolysis: Theory, Types and Applications, . Zhu, H., Rare Earth Metal Production by Molten Salt Electrolysis, in Encyclopedia of Applied Electrochemistry, G. Kreysa, K.-i. Ota, and R. Savinell, Editors. 2014, Springer New York. p. 1765-1772.

. Yuri Shtefanyuk, et al. Production of AI-Sc alloy by electrolysis of cryolite-scandium oxide melts. in TMS (The Minerals, Metals & Materials Society). 2015. Florida: John Wiley & Sons, inc.

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Claims (13)

REQUESTS 1. It is a pure scandium metal production method, and its feature is; a) Obtaining SCF3 compound from scandium compound in the form of (NH4)2NaScFs, b) Obtaining scandium salt mixtures as a result of adding CaCl2 and/or MgCl2 to the obtained SCF3 compound in order to reduce the melting temperature, c) obtained scandium salt mixtures electrolysis by the molten salt electrolysis method and includes the processing steps. 2. It is a production method according to claim 1, its feature is; The ScF3 compound mentioned in the a process step, the scandium compound in the o (NH4)2NaScFe form, is obtained by reacting with HCl in an aqueous medium and removing (NH4) and Na together with CI in the process step. 3. It is a production method according to claim 1, its feature is; It is the reaction of the scandium compound in the form of (NH4)2NaScF6 with HCl at 25-95 ((3 temperature, 1-6 hours). 4. It is a production method according to claim 1, its feature is; b is to obtain the scandium salt mixture of SCFs-CaClz by adding CaClz to the SCF3 compound mentioned in the process step. 5. It is a production method according to claim 1, its feature is; By adding MgCl2 to the SCF3 compound mentioned in the b process step, 8053-MgCl2 scandium salt mixture is obtained. 6. It is a production method according to claim 1, its feature is; b is to obtain the Sch-CaCl2-MgCIz scandium salt mixture by adding the CaCl2.MgCl2 mixture to the SCF3 compound mentioned in the b process step. 7. It is a production method according to claim 1, its feature is; the electrolysis process mentioned in the c process; o Melting the scandium salt mixture by heating it to a temperature of 800-1100“C, . Applying an electric current in the potential difference range of 2-8 volts to the molten salt bath obtained, through the anode and cathode, with this applied electric current, the Sc+3 ions in the melt are separated from the salt mixture and collected as pure scandium metal at the base of the electrolysis cell, It contains the process steps. 8. It is a production method in accordance with claim 7, its feature is; When it is desired to obtain aluminum-scandium alloys containing 0.2-0.8% scandium or aluminum-scandium master alloys containing 1-20% scandium; o adding aluminum metal to the electrolysis cell base, o adding scandium salt mixture to aluminum metal, . melting aluminum metal and fluoride-chloride scandium salt mixture by heating to 800-1100 cC, . Applying an electric current in the potential difference range of 2-8 volts to the molten salt bath obtained, through the anode and cathode, with this applied electric current, the aluminum-scandium alloy in the liquid state is separated from the molten fluoride-chloride salt mixture in the liquid state, and aluminum- Obtaining scandium alloy includes processing steps. 9. It is a production method in accordance with claim 81, its feature is; said scandium salt mixture is Sch-CaClz, ScFa-MgCl2 or ScFa-CaCl2-MgClz. 10. A production method according to claim 87 is a production method, and its feature is; when said anode material is graphite; fluoro-carbon gas or carbon monoxide-carbon dioxide gas is released. 11. It is a production method in accordance with Claim 10, its feature is; when carbon monoxide-carbon dioxide gas is desired to be released; o Dissolve scandium oxide as Sol'3 and O'2 ions and aluminum oxide as Al+3 and O'2 ions in the molten salt phase by adding 80203 or AI2O3 compounds to the salt mixture, not exceeding 10% by weight in total' It includes the process steps of controlling the potential difference applied to that circuit in such a way as to ensure that only 0'2 ions are oxidized without exceeding 6 volts. 12. A production method according to claim 8 is a production method, and its feature is; said anode material; When there is a stable anode material that does not interact with F', gas F2; 02 gas is released when it is a stable anode material that does not interact with O'. 13. A production method according to claim 12 is a production method, and its feature is; When 02 gas is asked to come out; o By adding SC203 or AI203 compounds to the salt mixture, not exceeding 10% by weight in total, scandium oxide is dissolved as SC+3 and 02 ions, and aluminum oxide as AI*3 and O'2 ions in the molten salt phase. It is to control the potential difference applied to that circuit in such a way that only 0'2 ions are oxidized, without exceeding 6 voItu, and it includes the process steps.