A method for treating complex low-grade platinum-palladium materials using a DC arc furnace

Abstract

The invention discloses a method for treating complex low-grade platinum-palladium materials by using a direct current arc furnace. The method comprises the following steps: pre-treating iron powder, coke and lime and the materials to ensure that the reaction efficiency between the materials is improved after the materials are put into the direct current arc furnace. The noble iron alloy is discharged into a mold with a plurality of cylindrical holes to form a 100-150 mm columnar noble iron alloy. The discharge and filling requirements of the melt are met at the same time, and the noble iron alloy is conveniently added to an intermediate frequency furnace for melting. After the columnar noble iron alloy is added to the intermediate frequency furnace for melting, a water quenching atomization system is used to prepare powder, and then a traditional purification process is used to purify and recover platinum-palladium. The noble iron alloy can be extracted from the steam residue, and then the platinum-palladium is purified and recovered from the noble iron alloy. After being divided into two processes, the overall recovery efficiency of platinum-palladium can be accelerated.

Description

Technical Field

[0001] The invention belongs to the field of low-grade platinum-palladium material processing methods, and in particular relates to a method for processing complex low-grade platinum-palladium materials by using a direct current arc furnace. Background Art

[0002] In the process of smelting and purifying platinum group metals, a small amount of complex intermediate materials with low platinum and palladium content, such as steam residue, will be produced. Generally, it contains Pt 50-300g / t, Pd 40-200g / t, Au 60-400g / t, and the impurity content is relatively high, including Cu 0.5-3%, Fe 1-6%, S15-33%, SiO2 1.5-28%, H2O 20-35%; at the same time, with the increasing shortage of platinum group metal raw materials, the demand for production capacity to recover and extract precious metals from various secondary resources containing platinum group metals continues to expand, and its overall composition is similar to that of steam residue. For example, the patent authorization public document CN103526023B proposes a method for regenerating a scrapped palladium extractant and recovering platinum group metals, which belongs to the field of extraction, separation and refining of platinum group metals. Based on the principle that low-boiling organic matter evaporates first and high-boiling organic matter evaporates later, the scrapped palladium extractant is regenerated by distillation-condensation, leaving the platinum group metals in the steam residue, and the platinum group metals are recovered by the method of staged low-temperature burning of the steam residue. The method of recovering the precious metals in the steam residue by low-temperature calcination of the steam residue has the problem of low efficiency;

[0003] Moreover, it is difficult to process such materials directly into the front-end process system of platinum group metals, and the metal yield is low, which increases the production cost and affects the quality of platinum and palladium products produced by concentrate. Therefore, such materials are generally stored or treated with a small amount of concentrate, which accumulates a large amount of pressure over time. Therefore, it is necessary to develop a simple and easy processing process to extract precious metals from complex materials containing platinum and palladium. Summary of the invention

[0004] The purpose of the present invention is to provide a processing method that can efficiently and conveniently extract precious metals from complex materials containing platinum, palladium and gold.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A method for treating complex low-grade platinum-palladium materials using a DC arc furnace comprises the following steps:

[0007] Step 1: Pretreatment, drying the complex low-grade platinum and palladium materials, controlling the moisture content of the dried materials to 10-12%, adding 10-15% iron powder, 2-5% coke and 8-16% lime and mixing them evenly;

[0008] Step 2: Capture smelting, add the material obtained in step 1 into a DC arc furnace, the electrode current of the DC arc furnace is 2000-4000A, the voltage is 80-120V, the smelting temperature is 1400-1600℃, the material reacts for 1-1.5h, and the slag is discharged after the liquid level reaches the slag discharge line, and the frozen layer is controlled to be 100-150mm. Repeat the feeding and slag discharge process until the total content of precious metals Pt, Pd and Au in the precious iron alloy reaches 20000-30000g / t, and then discharge the alloy;

[0009] Step 3: Column making: discharge the precious iron alloy into a mold with multiple cylindrical holes to make a 100-150mm column of precious iron alloy;

[0010] Step 4: Powdering: the obtained columnar precious iron alloy is added into the medium frequency furnace for melting and then powdered using a water quenching atomization system. The water pressure is controlled at 6-8MPa and the particle size is less than 80um.

[0011] Step 5: Purification and recovery: The obtained noble iron alloy atomized powder is purified to separate and recover platinum, palladium and gold.

[0012] A further technical solution is that in step one, the evenly mixed material is pressed into bricks.

[0013] A further technical solution is that in the step 1, the uniformly mixed material is granulated.

[0014] A further technical solution is that the mold is made of magnesia sand.

[0015] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0016] After pre-treatment, iron powder, coke, lime and materials are mixed in advance to ensure that the reaction efficiency between materials is improved after being put into the DC arc furnace. Among them, iron powder is used to capture precious metals such as gold, platinum and palladium in the materials, and coke is used to reduce the iron in the oxidized form of the materials to further capture precious metals. At the same time, coke is also used to reduce silicon in a small part of the materials to form iron-silicon alloys, increase the alloy melt resistance, and ensure the current stability of the DC arc furnace. Lime is used to slag with silicon oxide in the materials. Since there is a frozen layer in the arc furnace, it can protect the furnace bottom bricks from being corroded and reduce the temperature of the circulating water at the furnace bottom, so that the furnace body can operate safely, but the frozen layer should not exceed 1 50mm, the melt can be discharged smoothly from the alloy port when discharging the alloy, and the arc flow can be guaranteed to be stable and easy to control. The precious iron alloy is discharged into a mold with multiple cylindrical pits to make a 100-150mm columnar precious iron alloy. The discharge and filling requirements of the melt are met at the same time, and it is convenient to add the precious iron alloy to the medium frequency furnace for melting. After the columnar precious iron alloy is added to the medium frequency furnace for melting, a water quenching atomization system is used to make powder, and then the traditional purification process is used to purify and recover platinum and palladium. The precious iron alloy can be extracted from the steam residue, and then the platinum and palladium can be purified and recovered from the precious iron alloy. After being divided into two processes, the overall efficiency of recovering platinum and palladium can be accelerated. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the composition table of precious metal secondary resources;

[0018] Figure 2 This is the composition table of the residue from triple steaming. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0020] like Figure 1-Figure 2 shown.

[0021] Example 1: A method for treating complex low-grade platinum-palladium materials using a DC arc furnace, comprising the following steps:

[0022] Step 1: Pretreatment, dry the complex low-grade platinum and palladium materials, control the moisture content of the materials after drying to 10%, add 10% iron powder, 2% coke and 8% lime and mix them evenly; the complex low-grade platinum and palladium materials are secondary resources of precious metals, iron powder is used to capture precious metals such as gold, platinum and palladium in the materials, coke is used to reduce the iron in the oxidized form of the materials to further capture the precious metals, and coke is also used to reduce silicon in a small part of the materials to form an iron-silicon alloy, increase the alloy melt resistance, and ensure the current stability of the DC arc furnace. Lime is used to slag with silicon oxide in the materials. For example, 200kg of the dried precious metal secondary resources are added with 20kg iron powder, 4kg coke and 16kg lime for mixed brick pressing

[0023] Step 2: Capture smelting, add the material obtained in step 1 to an 800KW DC arc furnace, with a single charge of 200kg, a DC arc furnace electrode current of 2000A, a voltage of 80V, a smelting temperature of 1400°C, and a material reaction for 1h. Slag is discharged after the liquid level reaches the slag discharge line, and the freezing layer is controlled to be 100. Repeat the charging and slag discharge process until the total content of the precious metals Pt, Pd and Au in the precious iron alloy reaches 20000g / t, and then the alloy is discharged;

[0024] Step 3: Column making: discharge the precious iron alloy into a mold with multiple cylindrical holes to make 100 columnar precious iron alloys; after column making, the columnar precious iron alloy is easy to break into small pieces, which is convenient for manual addition into the crucible of the medium frequency furnace for melting.

[0025] Step 4: Powdering: the obtained columnar precious iron alloy is added into the medium frequency furnace for melting and then powdered using a water quenching atomization system. The water pressure is controlled at 6MPa and the particle size is less than 80um.

[0026] Step 5: Purification and recovery: The obtained noble iron alloy atomized powder is purified to separate and recover platinum, palladium and gold.

[0027] In the step one, the evenly mixed material is pressed into bricks by an existing brick press, which can reduce dust during feeding or conveying of materials in the production process. Alternatively, in the step one, the material is granulated by a high-pressure ball press. Granulating the evenly mixed material can also reduce dust during feeding or conveying of materials in the production process.

[0028] The mold is made of magnesia sand, and the mold is made by ramming magnesia sand. Before ramming, a carbon steel cylinder with a diameter of 100 mm is buried with a spacing of 10 mm. After ramming, the carbon steel cylinder is taken out to form a 100 mm cylindrical pit. After baking and drying, the alloy is discharged into the mold to ensure that the forming size of the precious iron alloy can be added to the subsequent medium frequency furnace for easy melting, while meeting the discharge and filling requirements of the melt.

[0029] Through pretreatment, iron powder, coke, lime and materials are mixed in advance to ensure that the reaction efficiency between materials is improved after being put into the DC arc furnace. Among them, iron powder is used to capture precious metals such as gold, platinum and palladium in the materials, and coke is used to reduce the iron in the oxidized form of the materials to further capture precious metals. At the same time, coke is also used to reduce silicon in a small part of the materials to form iron-silicon alloy, increase the alloy melt resistance, and ensure the current stability of the DC arc furnace. Lime is used to slag with silicon oxide in the materials. Since there is a frozen layer in the arc furnace, it can protect the furnace bottom bricks from being corroded and reduce the temperature of the circulating water at the furnace bottom, so that the furnace body can operate safely, but the frozen layer should not exceed The diameter of the alloy is more than 150mm. When discharging the alloy, the melt can be discharged smoothly from the alloy port. At the same time, the arc flow can be ensured to be stable and easy to control. The precious iron alloy is discharged into a mold with multiple cylindrical pits. After the 100mm columnar precious iron alloy is made, the discharge and filling requirements of the melt are met at the same time, and it is convenient to add the precious iron alloy to the medium frequency furnace for melting. After the columnar precious iron alloy is added to the medium frequency furnace for melting, it is powdered using a water quenching atomization system, and then the traditional purification process is used to purify and recover platinum and palladium. The precious iron alloy can be extracted from the steam residue, and then the platinum and palladium can be purified and recovered from the precious iron alloy. After being divided into two processes, the overall efficiency of recovering platinum and palladium can be accelerated.

[0030] Example 2: A method for treating complex low-grade platinum-palladium materials using a DC arc furnace, comprising the following steps:

[0031] Step 1: Pretreatment, drying the complex low-grade platinum-palladium material, controlling the moisture content of the material after drying to 12%, adding 15% iron powder, 5% coke and 16% lime and mixing them evenly, the complex low-grade platinum-palladium material is a three-times steaming residue, and adding 30kg iron powder, 10kg coke and 32kg lime to the 200kg three-times steaming residue after drying to mix and press bricks;

[0032] Step 2: Capture smelting, add the material obtained in step 1 to a DC arc furnace, with a single charge of 200 kg, a DC arc furnace electrode current of 4000 A, a voltage of 120 V, a smelting temperature of 1600 ° C, and a material reaction of 1.5 hours. Slag is discharged after the liquid level reaches the slag discharge line, and the freezing layer is controlled to be 150 mm. Repeat the charging and slag discharge process until the total content of the precious metals Pt, Pd and Au in the precious iron alloy reaches 30,000 g / t, and then the alloy is discharged;

[0033] Step 3: Column making: the precious iron alloy is discharged into a mold with multiple cylindrical holes to form a 150mm columnar precious iron alloy; after column making, the columnar precious iron alloy is easy to break into small pieces, which is convenient for manual addition into the crucible of the medium frequency furnace for melting;

[0034] Step 4: Powdering: the obtained columnar precious iron alloy is added into the medium frequency furnace for melting and then powdered using a water quenching atomization system. The water pressure is controlled at 8MPa and the particle size is less than 80um.

[0035] Step 5: Purification and recovery: The obtained noble iron alloy atomized powder is purified to separate and recover platinum, palladium and gold.

[0036] In the step one, the mixed material is pressed into bricks by an existing brick press, which can reduce dust during feeding or conveying of materials in the production process, or in the step one, the material is granulated by a high-pressure ball press, and granulating the mixed material can also reduce dust during feeding or conveying of materials in the production process.

[0037] The mold is made of magnesia sand. The mold is made of magnesia sand and is made by ramming magnesia sand. Before ramming, a carbon steel cylinder with a diameter of 150 mm is buried with an interval of 10 cm. After ramming, the carbon steel cylinder is taken out to form a 150 mm cylindrical pit. After baking and drying, the alloy is discharged into the mold to ensure that the forming size of the precious iron alloy can be added to the subsequent medium frequency furnace for easy melting, while meeting the discharge and filling requirements of the melt.

[0038] After pre-treatment, iron powder, coke, lime and materials are mixed in advance to ensure that the reaction efficiency between materials is improved after being put into the DC arc furnace. Iron powder is used to capture precious metals such as gold, platinum and palladium in the materials. Coke is used to reduce the iron in the oxidized form of the materials to further capture precious metals. At the same time, coke is also used to reduce silicon in a small part of the materials to form iron-silicon alloys, increase the alloy melt resistance, and ensure the current stability of the DC arc furnace. Lime is used to slag with silicon oxide in the materials. Since there is a frozen layer in the arc furnace, it can protect the furnace bottom bricks from being corroded and reduce the circulating water temperature at the furnace bottom, so that the furnace body can operate safely, but the frozen layer should not exceed 150mm, when discharging the alloy, the melt can be discharged smoothly from the alloy port, and the arc flow can be ensured to be stable and easy to control. The precious iron alloy is discharged into a mold with multiple cylindrical pits. After the 150mm columnar precious iron alloy is made, the discharge and filling requirements of the melt are met at the same time, and it is convenient to add the precious iron alloy to the medium frequency furnace for melting. After the columnar precious iron alloy is added to the medium frequency furnace for melting, it is powdered using a water quenching atomization system, and then the traditional purification process is used to purify and recover platinum and palladium. The precious iron alloy can be extracted from the steam residue, and then the platinum and palladium can be purified and recovered from the precious iron alloy. After being divided into two processes, the overall recovery efficiency of platinum and palladium can be accelerated.

[0039] The above are only preferred embodiments of the present invention.

Claims

1. A method for treating complex low-grade platinum-palladium materials using a DC arc furnace, characterized in that: The following steps are included: Step 1: Pretreatment, drying the complex low-grade platinum and palladium materials, controlling the moisture content of the dried materials to 10-12%, adding 10-15% iron powder, 2-5% coke and 8-16% lime and mixing them evenly; Step 2: Capture smelting, add the material obtained in step 1 into a DC arc furnace, the electrode current of the DC arc furnace is 2000-4000A, the voltage is 80-120V, the smelting temperature is 1400-1600℃, the material reacts for 1-1.5h, and the slag is discharged after the liquid level reaches the slag discharge line, and the frozen layer is controlled to be 100-150mm. Repeat the feeding and slag discharge process until the total content of precious metals Pt, Pd and Au in the precious iron alloy reaches 20000-30000g / t, and then discharge the alloy; Step 3: Column making: discharge the precious iron alloy into a mold with multiple cylindrical holes to make a 100-150mm column of precious iron alloy; Step 4: Powdering: the obtained columnar precious iron alloy is added into the medium frequency furnace for melting and then powdered using a water quenching atomization system, the water pressure is controlled at 6-8MPa, and the particle size is less than 80um; Step 5: Purification and recovery: The obtained noble iron alloy atomized powder is purified to separate and recover platinum, palladium and gold; In the step 1, the uniformly mixed material is pressed into bricks or in the step 1, the uniformly mixed material is granulated.

2. A method for treating complex low-grade platinum-palladium materials using a DC arc furnace according to claim 1, characterized in that: The mould is made of magnesia sand.

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