CN106757171A - Praseodymium iron alloy and its preparation method - Google Patents

Abstract

The invention discloses a praseodymium-iron alloy, wherein the content of praseodymium is 0-95 wt%, the balance is iron and inevitable impurities with the total amount of less than 0.5 wt%, wherein the oxygen content is less than or equal to 0.01 wt%, the carbon content is less than or equal to 0.01 wt%, the phosphorus content is less than or equal to 0.01 wt%, and the sulfur content is less than or equal to 0.005 wt%. The invention also discloses a preparation method of the praseodymium-iron alloy. The praseodymium-iron alloy prepared by the method has the advantages of uniform components, small segregation, low impurity content, high rare earth yield, low cost, no pollution, high rare earth yield when being applied to rare earth steel, obvious effect and suitability for large-scale industrial production.

Description

Praseodymium iron alloy and its preparation method

technical field

The invention relates to a rare earth metal material, in particular to a praseodymium-iron alloy and a preparation method thereof.

Background technique

At present, steel is the largest metal structural material and is widely used in construction, energy, transportation, aerospace and other fields. The application and research of rare earths in steel have also developed rapidly. The addition of rare earths to molten steel can desulfurize, deoxidize, change the shape of inclusions, etc., and can improve the plasticity, stamping performance, wear resistance and welding performance of steel. Various rare earth steels such as rare earth steel plates for automobiles, die steels, rails, etc. have been widely used.

The addition method of rare earth in the production process of rare earth steel has always been the focus of scientific research. The existing addition methods include wire feeding method, cored wire, rare earth iron intermediate alloy and other forms. At present, the effect is more obvious in the rare earth iron intermediate Alloy addition method. The technology for preparing rare earth iron master alloy mainly includes the following categories:

(1) Miscibility method.

The mixing method is also called the mixing method, which mainly uses an electric arc furnace or an intermediate frequency induction furnace to mix rare earth metals and iron to make alloys. This method is the method commonly used at present, and its process technology is simple, can make multi-element master alloy or application alloy, but also has deficiency: 1) rare earth metal easily local concentration is too high in molten iron, produces segregation; 2) this method The raw materials used are rare earth metals, especially for medium and heavy rare earth metals, the preparation process is complicated and the cost is high; 3) the melting temperature is high, because rare earth metals and pure iron are used as raw materials, the melting temperature requirement is high.

(2) molten salt electrolysis.

The preparation of rare earth iron master alloy by molten salt electrolysis mainly adopts iron consumable cathode method. For example, Chinese patent CN1827860 discloses a process and equipment for the production of dysprosium-iron alloy by molten salt electrolysis. It is proposed that under high temperature conditions, dysprosium oxide dissolved in the fluoride solution is ionized, and under the action of a DC electric field, dysprosium ions are precipitated on the surface of the iron cathode. It is reduced to metal dysprosium, and dysprosium is alloyed with iron to form dysprosium-iron alloy. This method has low production cost and simple process, but also has the following defects: the distribution of rare earth and iron in the alloy fluctuates greatly, is difficult to control, and the distribution error is as high as 3%-5%, which affects product consistency.

Contents of the invention

The technical problem solved by the present invention is to provide a praseodymium-iron alloy and its preparation method. The prepared praseodymium-iron alloy has uniform composition, small segregation, low impurity content, high rare earth yield, low cost, and no pollution. High efficiency, remarkable effect, suitable for large-scale industrial production.

The technical solution is as follows:

A praseodymium-iron alloy, the content of praseodymium is 0-95wt%, the balance is iron and unavoidable impurities less than 0.5wt% in total, wherein oxygen≤0.01wt%, carbon≤0.01wt%, phosphorus≤0.01wt%, Sulfur≤0.005wt%.

A preparation method of praseodymium-iron alloy, comprising:

In the equipment for the electrolysis of praseodymium-iron master alloy, under the fluoride molten salt electrolyte system of praseodymium fluoride and lithium fluoride, praseodymium oxide is used as the electrolytic raw material, and direct current is applied to electrolyze to obtain the praseodymium-iron master alloy;

The praseodymium-iron master alloy and iron are used as raw materials, and the praseodymium-iron alloy is prepared by melting; in the praseodymium-iron alloy, the content of praseodymium is 0-95wt%, and the balance is iron and unavoidable impurities whose total amount is less than 0.5wt%, wherein Oxygen≤0.01wt%, carbon≤0.01wt%, phosphorus≤0.01wt%, sulfur≤0.005wt%.

Further: The equipment for the electrolysis of praseodymium-iron master alloy uses graphite as the electrolytic cell, the graphite plate as the anode, the iron rod as the self-consumable cathode, and a receiver containing the alloy under the cathode.

Further: The equipment for melting the praseodymium-iron master alloy into the praseodymium-iron alloy is an intermediate frequency induction furnace, the melting process is carried out under vacuum conditions, and the crucible is a rare earth oxide crucible.

Further: the material of the receiver is iron, rare earth oxide or boron nitride.

Further: metal praseodymium or iron is also included in the vacuum melting process.

Compared with the prior art, the technical effect of the present invention includes: the present invention aims at the problems existing in the prior art, and develops a new process of molten salt electrolysis, and the prepared praseodymium-iron alloy has uniform composition, small segregation, low impurity content, and high rare earth yield , low cost, no pollution, high rare earth yield and remarkable effect when applied to rare earth steel, and is suitable for large-scale industrial production.

1, in the present invention, the advantage of praseodymium iron alloy is:

(1) Low impurity content.

The praseodymium-iron alloy provided by the invention adopts pure praseodymium oxide as a raw material, and the smelting crucible is made of iron and rare earth oxide substances, and the content of introduced impurities is small.

(2) The composition is uniform and the content of praseodymium is controllable.

Compared with the self-consumable cathode, the praseodymium-iron alloy involved in the present invention has more uniform components, and the praseodymium content can be precisely controlled. Practice has proved that high-performance rare earth steel products can be prepared by using the alloy of the invention.

2, the preparation method advantage of the praseodymium-iron alloy disclosed by the present invention is:

(1) Praseodymium oxide is used as the raw material for electrolysis, so only CO, CO ₂ and a very small amount of fluorine-containing gas are produced during the electrolysis process, which has little environmental pollution.

(2) The pure iron rod is used as the self-consumable cathode, and the electrolytically separated praseodymium and iron form a low-melting point praseodymium-iron alloy, which is beneficial to reduce the electrolysis temperature.

(3) The composition of the praseodymium-iron master alloy obtained by molten salt electrolysis is precisely controlled after vacuum melting. Due to the smelting under vacuum, the burning loss of rare earth is small, the yield is high, and the product quality is high.

3. The development and market prospects are broad.

With the development of national economic construction, in addition to requiring high strength and toughness of steel, it also requires good corrosion resistance, and rare earths can play a key role in this regard. Rare earths also play an important role in improving the toughness, plasticity, heat resistance, oxidation resistance and wear resistance of steel. my country is the largest country in steel production. In such a large-volume and wide-ranging field, it is of great significance to strengthen the application of rare earths. One of the important factors limiting the industrialization of rare earth steel is the way of adding rare earth to steel. The most effective way currently developed is to add rare earth iron master alloy. Taking Baotou Steel (Group) Company as an example with an annual output of 5 million tons of rare earth steel plates, it needs to consume 25,000 tons of 10% rare earth ferroalloy, which has significant economic benefits. After the implementation of the invention, on the one hand, it can improve the industrial structure of the region and enhance the scientific and technological strength of the region; on the other hand, the rare earth alloys are smelted every year, and all of them are applied to rare earth steels, which can not only generate great economic benefits, but also reverse my country's iron and steel situation is not ideal, and its application prospects are broad; it can find a way out for cheap rare earths, and help the healthy and sustainable development of the rare earth industry and the iron and steel industry.

Description of drawings

Fig. 1 is the structural representation of electrolytic praseodymium-iron master alloy equipment among the present invention;

Fig. 2 is a flow chart of the preparation process of praseodymium-iron alloy in the present invention.

detailed description

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art.

As shown in Figure 1, it is a schematic structural diagram of the electrolytic praseodymium-iron master alloy equipment in the present invention;

The equipment for the electrolysis of praseodymium-iron master alloy used in the present invention has a structure comprising: refractory brick 1, iron sleeve 2, rare earth oxide crucible 3, praseodymium-iron alloy 4, anode plate 5, iron cathode 6, electrolyte 7, electrolytic cell 8, Insulation layer 9, carbon stamping layer 10.

The electrolytic cell 8 is a graphite cell, and the outside of the graphite cell body is successively covered with a carbon stamping layer 10, an insulation layer 9, a refractory brick 1, and an iron sleeve 2; an iron cathode 6 is arranged in the middle of the graphite cell; The cathode 6 is provided with an anode plate 5; a rare earth oxide crucible 3 is provided at the center of the bottom of the graphite tank, and the rare earth oxide crucible 3 is opposite to the iron cathode 6. When in use, the graphite tank is equipped with an electrolyte 7, the electrolyte 7 adopts praseodymium fluoride and lithium fluoride molten salt electrolyte, and the rare earth oxide crucible 3 contains a praseodymium-iron alloy 4.

The preparation process of the praseodymium-iron alloy used for producing rare earth steel comprises the following steps:

Step 1: Graphite is used as the electrolytic cell, the graphite plate is used as the anode, the iron rod is used as the self-consumable cathode, and there is a receiver containing the alloy under the cathode;

The material of the receiver can be one of iron, rare earth oxide, and boron nitride.

Step 2: In the fluoride molten salt electrolyte system of praseodymium fluoride and lithium fluoride, praseodymium oxide is used as the electrolytic raw material, and direct current is applied to electrolyze to obtain the praseodymium-iron master alloy;

Step 3: Using the praseodymium-iron master alloy and iron as raw materials, a fusion method is used to prepare the praseodymium-iron alloy that meets the requirements.

The equipment for melting praseodymium-iron master alloy into praseodymium-iron alloy is an intermediate frequency induction furnace. The melting process is carried out under vacuum conditions, and the crucible is a rare earth oxide crucible.

In the praseodymium iron alloy, the content of praseodymium is 0-95wt%, and the balance is iron and unavoidable impurities with a total amount of less than 0.5wt%, wherein oxygen≤0.01wt%, carbon≤0.01wt%, phosphorus≤0.01wt%, sulfur ≤0.005wt%.

Metal detection is based on GB/T18115.1-2006 and other national standards, using ICP-MS testing; C testing is based on GB/T12690.13-1990, using high-frequency combustion-infrared testing; O testing is based on GB/T12690.4 -2003, tested by inert gas pulse-infrared method. The standard deviation S of the chemical composition is calculated by the following formula:

Wherein Xi is the chemical composition of the sample; the average value of X is the average value of the chemical composition of _n points of the sample, and n=20 in the present invention.

Example 1

A Φ600mm circular graphite electrolytic cell is used. The anode is composed of four graphite plates. The praseodymium fluoride in the electrolyte is 85wt%, the lithium fluoride is 15wt%, the cathode is a 70mm pure iron rod, the average current intensity is 4000A, and the anode current density is 0.5- 1.0A/cm ² , cathode current density 5-15A/cm ² , electrolysis temperature maintained at 900-1050°C, continuous electrolysis for 150 hours, 1112kg of praseodymium oxide was consumed, 1050kg of praseodymium-iron alloy was produced, the average praseodymium content was 90%, and the current efficiency 88%, the alloy composition results are shown in Table 1.

Table 1 Composition analysis results of praseodymium-iron master alloy/wt%

PR Fe C o P S Si mn 90.5 9.8 0.0082 0.0097 <0.01 <0.005 0.012 <0.005

Using the praseodymium-iron master alloy prepared in this example as a raw material, take 2 kg of praseodymium-iron master alloy, add 13 kg of iron bars, and carry out smelting in a 30 kg intermediate frequency vacuum induction furnace. The protective gas is argon, and the crucible is a praseodymium oxide crucible. The composition of the obtained ferropraseodymium is shown in Table 2.

Table 2 Composition analysis results of praseodymium-iron alloy/wt%

PR Fe C o P S Si mn 12.07 87.93 0.0083 0.0092 <0.01 <0.005 0.008 <0.005

Example 2

A Φ600mm circular graphite electrolytic cell is used. The anode is composed of four graphite plates. The praseodymium fluoride in the electrolyte is 85wt%, the lithium fluoride is 15wt%, the cathode is a 70mm pure iron rod, the average current intensity is 4000A, and the anode current density is 0.5- 1.0A/cm ² , cathode current density 5-15A/cm ² , electrolysis temperature maintained at 900-1050°C, continuous electrolysis for 150 hours, 1112kg of praseodymium oxide was consumed, 1050kg of praseodymium-iron alloy was produced, the average praseodymium content was 90%, and the current efficiency 88%, the alloy composition results are shown in Table 3.

Table 3 Composition analysis results of praseodymium-iron master alloy/wt%

PR Fe C o P S Si mn 90.5 9.8 0.0082 0.0097 <0.01 <0.005 0.012 <0.005

Using the praseodymium-iron master alloy prepared in this example as a raw material, take 4.5 kg of praseodymium-iron master alloy, add 10.5 kg of iron rods, and carry out smelting in a 30 kg intermediate frequency vacuum induction furnace, the protective gas is argon, and the crucible is a praseodymium oxide crucible. , the composition of praseodymium iron obtained after smelting is shown in Table 4.

Table 4 Composition analysis results of praseodymium-iron alloy/wt%

PR Fe C o P S Si mn 27.13 72.86 0.0088 0.0089 <0.01 <0.005 0.004 <0.005

Example 3

A Φ600mm circular graphite electrolytic cell is used. The anode is composed of four graphite plates. The praseodymium fluoride in the electrolyte is 85wt%, the lithium fluoride is 15wt%, the cathode is a 70mm pure iron rod, the average current intensity is 4000A, and the anode current density is 0.5- 1.0A/cm ² , cathode current density 5-15A/cm ² , electrolysis temperature maintained at 900-1050°C, continuous electrolysis for 150 hours, 1112kg of praseodymium oxide was consumed, 1050kg of praseodymium-iron alloy was produced, the average praseodymium content was 90%, and the current efficiency 88%, the alloy composition results are shown in Table 5.

Table 5 Composition analysis results of praseodymium-iron master alloy/wt%

PR Fe C o P S Si mn 90.5 9.8 0.0082 0.0097 <0.01 <0.005 0.012 <0.005

Using the praseodymium-iron master alloy prepared in this example as a raw material, take 8.5 kg of praseodymium-iron master alloy, add 6.5 kg of iron rods, and carry out smelting in a 30 kg intermediate frequency vacuum induction furnace, the protective gas is argon, and the crucible is a praseodymium oxide crucible. , the composition of praseodymium iron obtained after smelting is shown in Table 6.

Table 6 Composition analysis results of praseodymium-iron alloy/wt%

PR Fe C o P S Si mn 51.28 48.71 0.0071 0.0096 <0.01 <0.005 0.003 <0.005

Example 4

A Φ600mm circular graphite electrolytic cell is used. The anode is composed of four graphite plates. The praseodymium fluoride in the electrolyte is 85wt%, the lithium fluoride is 15wt%, the cathode is a 70mm pure iron rod, the average current intensity is 4000A, and the anode current density is 0.5- 1.0A/cm ² , cathode current density 5-15A/cm ² , electrolysis temperature maintained at 900-1050°C, continuous electrolysis for 150 hours, 1112kg of praseodymium oxide was consumed, 1050kg of praseodymium-iron alloy was produced, the average praseodymium content was 90%, and the current efficiency 88%, the alloy composition results are shown in Table 7.

Table 7 Composition analysis results of praseodymium-iron master alloy/wt%

PR Fe C o P S Si mn 90.5 9.8 0.0085 0.0094 <0.01 <0.005 0.012 <0.005

Using the praseodymium-iron master alloy prepared in this example as a raw material, take 12.1 kg of praseodymium-iron master alloy, add 2.9 kg of iron rods, and carry out smelting in a 30 kg intermediate frequency vacuum induction furnace, the protective gas is argon, and the crucible is a praseodymium oxide crucible. , the composition of praseodymium iron obtained after smelting is shown in Table 8.

Table 8 Composition analysis results of praseodymium-iron alloy/wt%

PR Fe C o P S Si mn 72.98 26.99 0.0076 0.0086 <0.01 <0.005 0.0024 <0.005

Example 5

A Φ600mm circular graphite electrolytic cell is used. The anode is composed of four graphite plates. The praseodymium fluoride in the electrolyte is 85wt%, the lithium fluoride is 15wt%, the cathode is a 70mm pure iron rod, the average current intensity is 4000A, and the anode current density is 0.5- 1.0A/cm ² , cathode current density 5-15A/cm ² , electrolysis temperature maintained at 900-1050°C, continuous electrolysis for 150 hours, 1112kg of praseodymium oxide was consumed, 1050kg of praseodymium-iron alloy was produced, the average praseodymium content was 90%, and the current efficiency 88%, the alloy composition results are shown in Table 9.

Table 9 Composition analysis results of praseodymium-iron master alloy/wt%

PR Fe C o P S Si mn 90.5 9.8 0.0085 0.0094 <0.01 <0.005 0.012 <0.005

Using the praseodymium-iron master alloy prepared in this example as a raw material, take 7 kg of praseodymium-iron master alloy, add 8 kg of metal praseodymium, and carry out smelting in a 30 kg intermediate frequency vacuum induction furnace, the protective gas is argon, and the crucible is a praseodymium oxide crucible. The composition of the obtained ferropraseodymium is shown in Table 10.

Table 10 Composition analysis results of praseodymium-iron alloy/wt%

PR Fe C o P S Si mn 95.56 4.43 0.0097 0.0076 <0.01 <0.005 0.010 <0.005

Example 6

A Φ650mm circular graphite electrolytic cell is used. The anode is composed of four graphite plates. The praseodymium fluoride in the electrolyte is 85wt%, the lithium fluoride is 15wt%, the cathode is a 75mm pure iron rod, the average current intensity is 5000A, and the anode current density is 0.4- 0.8A/cm ² , cathode current density 6-15A/cm ² , electrolysis temperature maintained at 900-1050°C, continuous electrolysis for 200 hours, 1812kg of praseodymium oxide was consumed, 1925kg of praseodymium-iron alloy was produced, the average praseodymium content was 80.02%, and the current efficiency 88%, the alloy composition results are shown in Table 11.

Table 11 Composition analysis results of praseodymium-iron master alloy/wt%

PR Fe C o P S Si mn 80.02 19.84 0.0075 0.0084 <0.01 <0.005 0.017 <0.005

Using the praseodymium-iron master alloy prepared in this example as a raw material, take 1.6 kg of praseodymium-iron master alloy, add 13.4 kg of iron rods, and carry out smelting in a 30 kg intermediate frequency vacuum induction furnace. The protective gas is argon, and the crucible is a praseodymium oxide crucible. , the composition of praseodymium iron obtained after smelting is shown in Table 12.

Table 12 Composition analysis results of praseodymium-iron alloy/wt%

PR Fe C o P S Si mn 8.53 91.46 0.0070 0.0080 <0.01 <0.005 0.003 <0.005

Example 7

A Φ650mm circular graphite electrolytic cell is used. The anode is composed of four graphite plates. The praseodymium fluoride in the electrolyte is 85wt%, the lithium fluoride is 15wt%, the cathode is a 75mm pure iron rod, the average current intensity is 5000A, and the anode current density is 0.4- 0.8A/cm ² , cathode current density 6-15A/cm ² , electrolysis temperature maintained at 900-1050°C, continuous electrolysis for 200 hours, 1812kg of praseodymium oxide was consumed, 1925kg of praseodymium-iron alloy was produced, the average praseodymium content was 80.02%, and the current efficiency 88%, the alloy composition results are shown in Table 13.

Table 13 Composition analysis results of praseodymium-iron master alloy/wt%

PR Fe C o P S Si mn 80.02 19.84 0.0075 0.0084 <0.01 <0.005 0.017 <0.005

Using the praseodymium-iron master alloy prepared in this example as a raw material, take 5.5 kg of praseodymium-iron master alloy, add 9.5 kg of iron rods, and carry out smelting in a 30 kg intermediate frequency vacuum induction furnace. The protective gas is argon, and the crucible is a praseodymium oxide crucible. , the composition of praseodymium iron obtained after smelting is shown in Table 14.

Table 14 Composition analysis results of praseodymium-iron alloy/wt%

PR Fe C o P S Si mn 29.33 70.66 0.0070 0.0086 <0.01 <0.005 0.0024 <0.005

Example 8

A Φ650mm circular graphite electrolytic cell is used. The anode is composed of four graphite plates. The praseodymium fluoride in the electrolyte is 85wt%, the lithium fluoride is 15wt%, the cathode is a 75mm pure iron rod, the average current intensity is 5000A, and the anode current density is 0.4- 0.8A/cm ² , cathode current density 6-15A/cm ² , electrolysis temperature maintained at 900-1050°C, continuous electrolysis for 200 hours, 1812kg of praseodymium oxide was consumed, 1925kg of praseodymium-iron alloy was produced, the average praseodymium content was 80.02%, and the current efficiency 88%, the alloy composition results are shown in Table 15.

Table 15 Composition analysis results of praseodymium-iron master alloy/wt%

PR Fe C o P S Si mn 80.02 19.84 0.0075 0.0084 <0.01 <0.005 0.017 <0.005

Using the praseodymium-iron master alloy prepared in this example as a raw material, take 8.6 kg of praseodymium-iron master alloy, add 6.4 kg of iron rods, and carry out smelting in a 30 kg intermediate frequency vacuum induction furnace. The protective gas is argon, and the crucible is a praseodymium oxide crucible. , the composition of praseodymium iron obtained after smelting is shown in Table 16.

Table 16 Composition analysis results of praseodymium-iron alloy/wt%

PR Fe C o P S Si mn 45.86 54.13 0.0064 0.0087 <0.01 <0.005 0.0021 <0.005

Example 9

A Φ650mm circular graphite electrolytic cell is used. The anode is composed of four graphite plates. The praseodymium fluoride in the electrolyte is 85wt%, the lithium fluoride is 15wt%, the cathode is a 75mm pure iron rod, the average current intensity is 5000A, and the anode current density is 0.4- 0.8A/cm ² , cathode current density 6-15A/cm ² , electrolysis temperature maintained at 900-1050°C, continuous electrolysis for 200 hours, 1812kg of praseodymium oxide was consumed, 1925kg of praseodymium-iron alloy was produced, the average praseodymium content was 80.02%, and the current efficiency 88%, the alloy composition results are shown in Table 17.

Table 17 Composition analysis results of praseodymium-iron master alloy/wt%

PR Fe C o P S Si mn 80.02 19.84 0.0075 0.0084 <0.01 <0.005 0.017 <0.005

Using the praseodymium-iron master alloy prepared in this example as a raw material, take 12.5 kg of praseodymium-iron master alloy, add 2.5 kg of iron rods, and carry out smelting in a 30 kg intermediate frequency vacuum induction furnace, the protective gas is argon, and the crucible is a praseodymium oxide crucible. , the composition of praseodymium iron obtained after smelting is shown in Table 18.

Table 18 Composition analysis results of praseodymium-iron alloy/wt%

PR Fe C o P S Si mn 66.66 33.32 0.0078 0.0090 <0.01 <0.005 0.0018 <0.005

Example 10

A Φ650mm circular graphite electrolytic cell is used. The anode is composed of four graphite plates. The praseodymium fluoride in the electrolyte is 85wt%, the lithium fluoride is 15wt%, the cathode is a 75mm pure iron rod, the average current intensity is 5000A, and the anode current density is 0.4- 0.8A/cm ² , cathode current density 6-15A/cm ² , electrolysis temperature maintained at 900-1050°C, continuous electrolysis for 200 hours, 1812kg of praseodymium oxide was consumed, 1925kg of praseodymium-iron alloy was produced, the average praseodymium content was 80.02%, and the current efficiency 88%, the alloy composition results are shown in Table 19.

Table 19 Composition analysis results of praseodymium-iron master alloy/wt%

PR Fe C o P S Si mn 80.02 19.84 0.0075 0.0084 <0.01 <0.005 0.017 <0.005

Using the praseodymium-iron master alloy prepared in this example as a raw material, take 5 kg of praseodymium-iron master alloy, add 10 kg of metal praseodymium, and carry out smelting in a 30 kg intermediate frequency vacuum induction furnace, the protective gas is argon, and the crucible is a praseodymium oxide crucible. The composition of the obtained ferropraseodymium is shown in Table 20.

Table 20 Composition analysis results of praseodymium-iron alloy/wt%

PR Fe C o P S Si mn 93.33 6.66 0.0094 0.0093 <0.01 <0.005 0.0034 <0.005

Example 11

A Φ700mm circular graphite electrolytic cell is used, the anode is composed of four graphite plates, the praseodymium fluoride in the electrolyte is 85wt%, the lithium fluoride is 15wt%, the cathode is an 80mm pure iron rod, the average current intensity is 5500A, and the anode current density is 0.3- 0.7A/cm ² , cathode current density 3-12A/cm ² , electrolysis temperature maintained at 900-1050°C, continuous electrolysis for 300 hours, 3011kg of praseodymium oxide was consumed, 2694kg of praseodymium-iron alloy was produced, the average praseodymium content was 95.06%, and the current efficiency 88.90%, the alloy composition results are shown in Table 21.

Table 21 Composition analysis results of praseodymium-iron master alloy/wt%

PR Fe C o P S Si mn 95.06 4.64 0.0042 0.0065 <0.01 <0.005 0.014 <0.005

Using the praseodymium-iron master alloy prepared in this example as a raw material, take 3.5 kg of praseodymium-iron master alloy, add 11.5 kg of metal iron, and carry out smelting in a 30 kg intermediate frequency vacuum induction furnace, the protective gas is argon, and the crucible is a praseodymium oxide crucible. , the composition of praseodymium iron obtained after smelting is shown in Table 22.

Table 22 Composition analysis results of praseodymium-iron alloy/wt%

PR Fe C o P S Si mn 22.16 77.83 0.0040 0.0071 <0.01 <0.005 0.0088 <0.005

Example 12

A Φ700mm circular graphite electrolytic cell is used, the anode is composed of four graphite plates, the praseodymium fluoride in the electrolyte is 85wt%, the lithium fluoride is 15wt%, the cathode is an 80mm pure iron rod, the average current intensity is 5500A, and the anode current density is 0.3- 0.7A/cm ² , cathode current density 3-12A/cm ² , electrolysis temperature maintained at 900-1050°C, continuous electrolysis for 300 hours, 3011kg of praseodymium oxide was consumed, 2694kg of praseodymium-iron alloy was produced, the average praseodymium content was 95.06%, and the current efficiency 88.90%, the alloy composition results are shown in Table 23.

Table 23 Composition analysis results of praseodymium-iron master alloy/wt%

PR Fe C o P S Si mn 95.06 4.64 0.0042 0.0065 <0.01 <0.005 0.014 <0.005

Using the praseodymium-iron master alloy prepared in this example as a raw material, take 6.3 kg of praseodymium-iron master alloy, add 8.7 kg of metal iron, and carry out smelting in a 30 kg intermediate frequency vacuum induction furnace. The protective gas is argon, and the crucible is a praseodymium oxide crucible. , the composition of praseodymium iron obtained after smelting is shown in Table 24.

Table 24 Composition analysis results of praseodymium-iron alloy/wt%

PR Fe C o P S Si mn 39.9 60.01 0.0038 0.0072 <0.01 <0.005 0.0079 <0.005

Example 13

A Φ700mm circular graphite electrolytic cell is used, the anode is composed of four graphite plates, the praseodymium fluoride in the electrolyte is 85wt%, the lithium fluoride is 15wt%, the cathode is an 80mm pure iron rod, the average current intensity is 5500A, and the anode current density is 0.3- 0.7A/cm ² , cathode current density 3-12A/cm ² , electrolysis temperature maintained at 900-1050°C, continuous electrolysis for 300 hours, 3011kg of praseodymium oxide was consumed, 2694kg of praseodymium-iron alloy was produced, the average praseodymium content was 95.06%, and the current efficiency 88.90%, the alloy composition results are shown in Table 25.

Table 25 Composition analysis results of praseodymium-iron master alloy/wt%

PR Fe C o P S Si mn 95.06 4.64 0.0042 0.0065 <0.01 <0.005 0.014 <0.005

Using the praseodymium-iron master alloy prepared in this example as a raw material, take 9.5 kg of praseodymium-iron master alloy, add 5.5 kg of metal iron, and carry out smelting in a 30 kg intermediate frequency vacuum induction furnace, the protective gas is argon, and the crucible is a praseodymium oxide crucible. , the composition of praseodymium iron obtained after smelting is shown in Table 26.

Table 26 Composition analysis results of praseodymium-iron alloy/wt%

PR Fe C o P S Si mn 59.97 39.62 0.0041 0.0075 <0.01 <0.005 0.0080 <0.005

Example 14

A Φ700mm circular graphite electrolytic cell is used, the anode is composed of four graphite plates, the praseodymium fluoride in the electrolyte is 85wt%, the lithium fluoride is 15wt%, the cathode is an 80mm pure iron rod, the average current intensity is 5500A, and the anode current density is 0.3- 0.7A/cm ² , cathode current density 3-12A/cm ² , electrolysis temperature maintained at 900-1050°C, continuous electrolysis for 300 hours, 3011kg of praseodymium oxide was consumed, 2694kg of praseodymium-iron alloy was produced, the average praseodymium content was 95.06%, and the current efficiency 88.90%, the alloy composition results are shown in Table 27.

Table 27 Composition analysis results of praseodymium-iron master alloy/wt%

PR Fe C o P S Si mn 95.06 4.64 0.0042 0.0065 <0.01 <0.005 0.014 <0.005

Using the praseodymium-iron master alloy prepared in this example as a raw material, take 12.6 kg of praseodymium-iron master alloy, add 2.4 kg of metal iron, and smelt it in a 30 kg intermediate frequency vacuum induction furnace. The protective gas is argon, and the crucible is a praseodymium oxide crucible. , the composition of praseodymium iron obtained after smelting is shown in Table 28.

Table 28 Composition analysis results of praseodymium-iron alloy/wt%

PR Fe C o P S Si mn 79.80 20.09 0.0046 0.0066 <0.01 <0.005 0.0079 <0.005

The terms used herein are terms of description and illustration, rather than limitation. Since the present invention can be embodied in many forms without departing from the spirit or essence of the invention, it should be understood that the above-described embodiments are not limited to any of the foregoing details, but should be construed broadly within the spirit and scope of the appended claims. , all changes and modifications falling within the scope of the claims or their equivalents shall be covered by the appended claims.

Claims (6)

1. a kind of praseodymium ferroalloy, it is characterised in that：The content of praseodymium is 0~95wt%, and surplus is that iron and total amount are less than 0.5wt% Inevitable impurity, wherein oxygen≤0.01wt%, carbon≤0.01wt%, phosphorus≤0.01wt%, sulphur≤0.005wt%.

2. a kind of preparation method of praseodymium ferroalloy, including：

In the equipment of electrolysis praseodymium iron intermediate alloy, under the fluoride molten salt electrolyte system of praseodymium fluoride and lithium fluoride, with oxygen It is electrolysis raw material to change praseodymium, is passed through direct current electrolysis and obtains praseodymium iron intermediate alloy；

Using praseodymium iron intermediate alloy and iron as raw material, convert method and prepare praseodymium ferroalloy using molten；In praseodymium ferroalloy, the content of praseodymium is 0~95wt%, surplus is the inevitable impurity of iron and total amount less than 0.5wt%, wherein oxygen≤0.01wt%, carbon≤ 0.01wt%, phosphorus≤0.01wt%, sulphur≤0.005wt%.

3. the preparation method of praseodymium ferroalloy as claimed in claim 2, it is characterised in that：The equipment of praseodymium iron intermediate alloy is electrolysed with stone Ink does electrolytic cell, and graphite cake has the receiver for containing alloy as anode, iron staff as consumable negative electrode, negative electrode lower section.

4. the preparation method of praseodymium ferroalloy as claimed in claim 3, it is characterised in that：Praseodymium iron intermediate alloy melts converts praseodymium ferroalloy Equipment is intermediate frequency furnace, and molten to convert process and carry out under vacuum, crucible uses rare earth oxide crucible.

5. the preparation method of praseodymium ferroalloy as claimed in claim 3, it is characterised in that：Receiver material selection iron, rare-earth oxidation Thing or boron nitride.

6. the preparation method of praseodymium ferroalloy as claimed in claim 2, it is characterised in that：Also include metal during vacuum melts and converts Praseodymium or iron.