CN110482495B - Device and method for purifying crude selenium through oxidation-evaporation-carbothermic reduction - Google Patents
Device and method for purifying crude selenium through oxidation-evaporation-carbothermic reduction Download PDFInfo
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- CN110482495B CN110482495B CN201910608321.2A CN201910608321A CN110482495B CN 110482495 B CN110482495 B CN 110482495B CN 201910608321 A CN201910608321 A CN 201910608321A CN 110482495 B CN110482495 B CN 110482495B
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- C01B19/00—Selenium; Tellurium; Compounds thereof
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Abstract
The invention provides a device and a method for purifying crude selenium by oxidation-evaporation-carbothermic reduction, belonging to the technical field of crude selenium purification. The oxidation-evaporation provided by the inventionThe device for purifying the crude selenium by carbon-carbon thermal reduction comprises an oxidation device and an evaporation-carbon thermal reduction device; the method uses an oxidation device to oxidize the crude selenium firstly, so that the main element selenium in the crude selenium volatilizes, the efficient separation of the selenium from other impurity elements is realized, and selenium oxide is obtained; and then an evaporation-carbon thermal reduction device is used for volatilizing the selenium oxide and carrying out reduction reaction to finally obtain the refined selenium. The invention also provides a method for purifying crude selenium by using the device, which is simple and quick to operate and does not generate toxic substance H2Se, the purity of the obtained refined selenium is high. The results of the examples show that the purity of the refined selenium obtained by the method can reach 99.94 percent, the recovery rate of the selenium can reach 95.45 percent, and the method meets the 3N selenium standard.
Description
Technical Field
The invention relates to the technical field of crude selenium purification, in particular to a device and a method for purifying crude selenium through oxidation-evaporation-carbothermic reduction.
Background
In recent years, with the development of aerospace, atomic energy, solar energy, electronic semiconductors, selenium-rich foods and selenium agricultural health fields, the demand for selenium is increasing day by day, and selenium has become a key material for supporting high-tech development and new product development. However, the abundance of rare-earth selenium is only 5 × 10-6Percent, and the crude selenium often contains impurity elements such as Te, Pb, Cu, S and the like, so the improvement of the separation and purification technology of selenium is a key problem to be solved urgently in the development of the selenium industry.
The method for purifying selenium on the premise of the prior art mainly comprises a chemical purification method and a physical purification method, wherein the chemical purification method mainly comprises the steps of oxidizing crude selenium and reducing the selenium by using a proper chemical reagent to obtain refined selenium. The chemical purification method usually involves toxic and harmful substances, and the pressure of production safety problems is high; and easily generate highly toxic gas H2Se, the method is only used for preparing a small amount of ultra-high pure selenium or selenide. The physical purification method utilizes the vapor pressure difference of elemental tellurium, copper, lead, iron, gold, silver and other impurity components in selenium and crude selenium, and the selenium has higher vapor pressure and is easy to volatilize so as to be separated from the impurities. CN105600758 proposes a wet refining process for purifying crude selenium, namely NaOH is added into absorption liquid of an alloy converting tower to remove part of base metals, thiourea and HCl are sequentially used for deep impurity reduction, a relatively pure selenious acid solution is obtained by filtration, and SO is utilized2Reducing to obtain crude selenium powder with higher purity; CN1636867 proposes a method for purifying selenium raw material by drying-vacuum evaporation process, i.e. washing selenium raw material, drying to water content of about 0.1%, and vacuum evaporating and purifying in a vacuum furnace. However, these methods have the defects of complicated process and low quality of the obtained selenium.
Disclosure of Invention
In view of the above, the present invention aims to provide an apparatus and a method for purifying crude selenium by oxidation-evaporation-carbothermic reduction. The method for purifying the crude selenium provided by the invention is simple and rapid to operate, and does not generate toxic substance H2Se, the purity of the obtained refined selenium is high.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a device for purifying crude selenium by oxidation-evaporation-carbothermic reduction, which comprises an oxidation device and an evaporation-carbothermic reduction device;
the oxidation device comprises a heating oxidation area and a gas collecting area, and the heating oxidation area is provided with an oxygen blowing port; the inlet of the gas collecting area is communicated with the outlet of the heating oxidation area, and the gas collecting area is provided with a tail gas outlet;
the evaporation-carbon thermal reduction device comprises an evaporation area, a carbon thermal reduction area and a condensation area which are sequentially communicated from bottom to top; a separation net is arranged at the thermal communication position of the evaporation area and the carbon; the condensation zone is provided with a tail gas outlet.
The invention provides a method for purifying crude selenium by using the device, which comprises the following steps:
(1) placing the crude selenium raw material in a heating oxidation zone of the oxidation device, introducing oxidizing gas for oxidation reaction, and collecting selenium oxide from a gas collection zone;
(2) and placing the selenium oxide in an evaporation area of an evaporation-carbothermic reduction device, placing a reducing agent in a carbothermic reduction area of the evaporation-carbothermic reduction device, heating the reducing agent and the selenium oxide in sequence, volatilizing the selenium oxide in the evaporation area, then entering the carbothermic reduction area for reduction reaction, and collecting refined selenium from a condensation area.
Preferably, the oxidizing gas in step (1) is oxygen and/or air.
Preferably, the introducing speed of the oxidizing gas is 0.3-0.5 m/min.
Preferably, the temperature of the oxidation reaction in the step (1) is 280-500 ℃, and the time is 1.5-2.5 h.
Preferably, the reducing agent in the step (2) is one or more of charcoal, coke and anthracite.
Preferably, the mass ratio of the selenium oxide to the reducing agent in the step (2) is less than or equal to 6: 1.
Preferably, the heating temperature of the reducing agent in the step (2) is 700-800 ℃, and the heating temperature of the selenium oxide is 280-550 ℃.
Preferably, the time of the reduction reaction in the step (2) is 1-2 h.
Preferably, the temperature of the condensation zone in the step (2) is 150-300 ℃.
The invention provides a device for purifying crude selenium by oxidation-evaporation-carbothermic reduction, which comprises an oxidation device and an evaporation-carbothermic reduction device. The method uses an oxidation device to oxidize the crude selenium firstly, so that the main element selenium in the crude selenium volatilizes, the efficient separation of the selenium from other impurity elements is realized, and selenium oxide is obtained; and then an evaporation-carbon thermal reduction device is used for volatilizing the selenium oxide and carrying out reduction reaction to finally obtain the refined selenium.
The invention also provides a method for purifying crude selenium by using the device, which is simple and quick to operate and does not generate toxic substance H2Se, the purity of the obtained refined selenium is high. The results of the examples show that the purity of the refined selenium obtained by the method can reach 99.94 percent, the recovery rate of the selenium can reach 95.45 percent, and the method meets the 3N selenium standard.
Drawings
FIG. 1 is a schematic view of an oxidation apparatus of the present invention, wherein 1-an oxygen blowing port, 2-a heating oxidation zone, 3-a gas collection zone, 4-a holding vessel, and 5-a tail gas outlet;
FIG. 2 is a schematic diagram of an evaporation-carbothermic reduction apparatus of the present invention, wherein 6-evaporation zone, 7-separation net, 8-carbothermic reduction zone, 9-condensation zone, 10-off-gas outlet.
Detailed Description
The invention provides a device for purifying crude selenium by oxidation-evaporation-carbothermic reduction, which comprises an oxidation device and an evaporation-carbothermic reduction device;
the oxidation device comprises a heating oxidation area and a gas collecting area, and the heating oxidation area is provided with an oxygen blowing port; the inlet of the gas collecting area is communicated with the outlet of the heating oxidation area, and the gas collecting area is provided with a tail gas outlet;
the evaporation-carbon thermal reduction device comprises an evaporation area, a carbon thermal reduction area and a condensation area which are sequentially communicated from bottom to top; a separation net is arranged at the thermal communication position of the evaporation area and the carbon; the condensation zone is provided with a tail gas outlet.
The device for purifying crude selenium by oxidation-evaporation-carbothermic reduction provided by the invention comprises an oxidation device, as shown in figure 1. In the present invention, the oxidation device comprises a heated oxidation zone 2, the heated oxidation zone 2 is preferably tubular in shape, the length of the heated oxidation zone is preferably 120cm, and the inner diameter of the heated oxidation zone is preferably 10 cm; the heating oxidation zone is provided with an oxygen blowing port 1, the oxygen blowing port is an oxidizing gas inlet of the heating oxidation zone, and the shape of the oxygen blowing port is preferably tubular; the invention has no special requirements on the inner diameter and the length of the oxygen blowing opening, and can ensure that oxidizing gas can smoothly enter. In the invention, the heating oxidation zone preferably comprises a material containing vessel 4, and the material containing vessel is preferably placed in the middle of the heating oxidation zone and is used for placing the crude selenium raw material; in a particular embodiment of the invention, the holding vessel is preferably a graphite boat. In the invention, the selenium simple substance in the crude selenium is oxidized into selenium oxide gas in the heating oxidation zone, and other impurities are still remained in the material containing vessel, thereby realizing the high-efficiency separation of the selenium and other impurity elements.
In the invention, the oxidation device comprises a gas collecting region 3, the inlet of the gas collecting region 3 is communicated with the outlet of the heating oxidation region 2, and the gas collecting region is provided with a tail gas outlet 5. In the present invention, the gas collecting region is preferably tubular in shape, preferably 20cm in length and preferably 10cm in internal diameter; the gas collecting area and the heating oxidation area are preferably communicated through a section of thin pipe, the length of the thin pipe is preferably 5cm, the inner diameter of the thin pipe is preferably 1cm, in the invention, the tail gas outlet is preferably positioned in the middle of the tail end of the gas collecting area, and the shape of the tail gas outlet is preferably tubular; the invention has no special requirements on the inner diameter and the length of the tail gas outlet, and can smoothly discharge the tail gas. In the invention, the gas collecting region is used for collecting selenium oxide gas after oxidation and volatilization, the selenium oxide gas is cooled after entering the gas collecting region and is condensed on the inner wall of the gas collecting region, and the rest gas is discharged through the tail gas outlet.
The invention has no special requirements on the material of the oxidation device, and can meet the heating requirements of the invention.
The device for purifying crude selenium by oxidation-evaporation-carbothermic reduction provided by the invention comprises an evaporation-carbothermic reduction device, as shown in figure 2. In the invention, the evaporation-carbon thermal reduction device comprises an evaporation zone 6, a carbon thermal reduction zone 8 and a condensation zone 9 which are sequentially communicated from bottom to top. In the present invention, the evaporation zone is preferably cylindrical in shape, with a height of preferably 10cm and an internal diameter of preferably 8 cm. In the present invention, the evaporation zone preferably comprises a material container, and the material container is preferably placed at the bottom of the evaporation zone and is used for placing selenium oxide. In the present invention, the bottom outside the evaporation zone is preferably provided with a heating device, and the heating device is preferably a resistance furnace. The invention heats the evaporation area to evaporate the selenium oxide into selenium oxide gas.
In the invention, the inlet of the carbothermic reduction zone is communicated with the outlet of the evaporation zone, and a separation net 7 is arranged at the communication position. In the present invention, the carbothermic reduction zone is preferably cylindrical in shape, preferably 15cm in height, and has the same inner diameter as the evaporation zone; the material of the separation net is preferably stainless steel; the invention has no special requirements on the aperture of the separation net, and can ensure that the reducing agent does not fall off and the gas stably circulates. In the present invention, a heating device is preferably provided around the outside of the carbothermic reduction region, and the heating device is preferably a crucible resistance furnace. The invention can reduce the selenium oxide gas into the elemental selenium in the carbothermic region by heating the carbothermic region.
In the invention, the inlet of the condensation zone is communicated with the outlet of the carbothermic reduction zone, and the condensation zone is provided with a tail gas outlet 10. In the present invention, the shape of the condensation zone is preferably a truncated cone shape with a narrow top and a wide bottom, and the inner diameter of the top part is preferably 25cm, the inner diameter of the bottom part is preferably 15cm, and the height is preferably 20 cm. In the present invention, the tail gas outlet is preferably located at the top middle part of the condensation zone, and the shape of the tail gas outlet is preferably tubular; the invention has no special requirements on the inner diameter and the length of the tail gas outlet, and can smoothly discharge the tail gas. In the invention, the condensation zone condenses the reduced elemental selenium gas into a solid and attaches the solid to the inner wall of the condensation zone.
The evaporation-carbon thermal reduction device has no special requirements on the material of the evaporation-carbon thermal reduction device, and can meet the heating requirements of the evaporation-carbon thermal reduction device.
The invention provides a method for purifying crude selenium by using the device, which comprises the following steps:
(1) placing the crude selenium raw material in a heating oxidation zone of the oxidation device, introducing oxidizing gas for oxidation reaction, and collecting selenium oxide from a gas collection zone;
(2) and placing the selenium oxide in an evaporation area of an evaporation-carbothermic reduction device, placing a reducing agent in a carbothermic reduction area of the evaporation-carbothermic reduction device, heating the reducing agent and the selenium oxide in sequence, volatilizing the selenium oxide in the evaporation area, then entering the carbothermic reduction area for reduction reaction, and collecting refined selenium from a condensation area.
The method comprises the steps of placing a crude selenium raw material in a heating oxidation area of an oxidation device, introducing oxidizing gas to perform oxidation reaction, and collecting selenium oxide from a gas collection area. In the invention, the oxidizing gas is preferably oxygen and/or air, and the introducing speed of the oxidizing gas is preferably 0.3-0.5 m/min, and more preferably 0.4 m/min; the temperature of the oxidation reaction is preferably 280-500 ℃, more preferably 300-400 ℃, and the time is preferably 1.5-2.5 h, more preferably 2 h.
In the present invention, the reaction formula of the oxidation reaction is shown as formula I:
Se(s)+O2(g)＝SeO2(s) formula I.
After the selenium oxide is obtained, the selenium oxide is placed in an evaporation area of an evaporation-carbothermic reduction device, a reducing agent is placed in a carbothermic reduction area of the evaporation-carbothermic reduction device, the reducing agent and the selenium oxide are sequentially heated, the selenium oxide in the evaporation area is volatilized and then enters the carbothermic reduction area to carry out reduction reaction, and refined selenium is collected from a condensation area. In the invention, the reducing agent is preferably one or more of charcoal, coke and anthracite; the mass ratio of the selenium oxide to the reducing agent is preferably less than or equal to 6:1, and more preferably less than or equal to 5: 1; the reducing agent can be recycled. In the invention, the heating temperature of the reducing agent is preferably 700-800 DEG CMore preferably 720-780 ℃, and the heating temperature of the selenium oxide is preferably 280-550 ℃, more preferably 300-500 ℃; the present invention preferably first heats the reducing agent to the reduction temperature and then heats the selenium oxide. In the invention, the time of the reduction reaction is preferably 1-2 h, and more preferably 1.5 h; according to the invention, the time of the reduction reaction is calculated from the time when the selenium oxide is heated to the required temperature, and the reduction reaction is finished after the tail gas outlet does not produce tail gas any more. In the invention, the temperature of the condensation zone is preferably 150-300 ℃, and more preferably 250 ℃. The invention heats the selenium oxide to ensure that the SeO in the evaporation zone2And after being volatilized, the selenium gas enters a carbothermic reduction area to react with a reducing agent to generate selenium elementary gas, and the selenium elementary gas enters a condensation area to be condensed into selenium elementary solid and attached to the inner wall of the condensation area.
In the present invention, the reaction formula of the reduction reaction is shown as formula II:
SeO2(g)+C(s)＝Se(s)+CO2(g) formula II.
The device and method for purifying crude selenium by oxidation-evaporation-carbothermic reduction provided by the present invention are described in detail with reference to the following examples, but they should not be construed as limiting the scope of the present invention.
Example 1
Crushing crude selenium raw material with purity of 98%, placing into a graphite boat, placing the graphite boat into a heating zone of a crude selenium oxidation device, reacting at 500 deg.C, slowly introducing oxygen (flow rate of 0.5m/min) from an oxygen blowing port, heating and maintaining for 2h, and collecting white crystals SeO from the inner wall of a gas collecting zone after reaction2；
The collected white crystals are SeO2Placing in an evaporation zone of an evaporation-carbothermic apparatus, placing a reducing agent charcoal in a carbothermic zone of the evaporation-carbothermic apparatus, wherein SeO2The mass ratio of the reducing agent to the reducing agent is 6: 1; then the charcoal is heated to 700 ℃ and then the SeO is added2Heating to 280 ℃, carrying out reduction reaction for 1h, and collecting refined selenium in the tube wall of the condensation area and the condenser after the reaction is finished.
And detecting the purity of the obtained refined selenium by using an inductively coupled plasma mass spectrometer (ICP-MS), wherein the detection standard refers to the non-ferrous metal industry standard YS/T223-2007 and YS/T226.13-2009 of the people's republic of China.
The detection proves that the purity of the refined selenium obtained by the method reaches 99.93 percent, the recovery rate of the selenium is 92.82 percent, the refined selenium contains impurities of Te0.0037 percent, Cu0.0009 percent and lead 0.0017 percent, and all the impurities meet the 3N selenium standard.
Example 2
Crushing crude selenium raw material with purity of 99%, placing into a graphite boat, placing the graphite boat into a heating zone of a crude selenium oxidation device, reacting at 450 deg.C, slowly introducing oxygen (flow rate of 0.5m/min) from an oxygen blowing port, heating and maintaining for 1.5h, and collecting white crystal SeO from the inner wall of a gas collection zone after reaction2；
The collected white crystals are SeO2Placing in an evaporation zone of an evaporation-carbothermic apparatus, placing a reducing agent charcoal in a carbothermic zone of the evaporation-carbothermic apparatus, wherein SeO2The mass ratio of the reducing agent to the reducing agent is 5: 1; then the charcoal is heated to 750 ℃ and then the SeO is added2Heating to 350 ℃, carrying out reduction reaction for 1.5h, and collecting refined selenium in the tube wall of the condensation area and the condenser after the reaction is finished.
And detecting the purity of the obtained refined selenium by using an inductively coupled plasma mass spectrometer (ICP-MS), wherein the detection standard refers to the non-ferrous metal industry standard YS/T223-2007 and YS/T226.13-2009 of the people's republic of China.
The detection proves that the purity of the refined selenium obtained by the method reaches 99.91 percent, the recovery rate of the selenium is 92.63 percent, the refined selenium contains impurities of Te0.0048 percent, Cu0.0007 percent and lead 0.0015 percent, and all the impurities meet the 3N selenium standard.
Example 3
Crushing crude selenium raw material with purity of 99.5%, placing into graphite boat, placing graphite boat into heating zone of crude selenium oxidation device, reacting at 550 deg.C, slowly introducing air (flow rate of 0.5m/min) from oxygen blowing port, heating and maintaining for 2.5 hr, and collecting white crystal SeO from inner wall of gas collection zone after reaction2；
Will whitenColored crystal SeO2Placing in an evaporation zone of an evaporation-carbothermic apparatus, placing a reducing agent charcoal in a carbothermic zone of the evaporation-carbothermic apparatus, wherein SeO2The mass ratio of the reducing agent to the reducing agent is 5.5: 1; then the charcoal is heated to 800 ℃ and then the SeO is added2Heating to 550 ℃, carrying out reduction reaction, and collecting refined selenium in the tube wall of the condensation area and the condenser after the reaction is finished.
And detecting the purity of the obtained refined selenium by using an inductively coupled plasma mass spectrometer (ICP-MS), wherein the detection standard refers to the non-ferrous metal industry standard YS/T223-2007 and YS/T226.13-2009 of the people's republic of China.
The detection proves that the purity of the refined selenium obtained by the method reaches 99.94 percent, the recovery rate of the selenium is 95.45 percent, the refined selenium contains 0.0060 percent of impurity Te0.0060 percent, 0.0006 percent of impurity Cu0.0014 percent of lead, and the purity and the recovery rate all meet the 3N selenium standard.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (5)
1. A method for purifying crude selenium by oxidation-evaporation-carbothermic reduction is characterized by comprising the following steps:
(1) placing the crude selenium raw material in a heating oxidation zone of an oxidation device, introducing oxidizing gas for oxidation reaction, and collecting selenium oxide from a gas collection zone;
(2) placing the selenium oxide in an evaporation area of an evaporation-carbothermic reduction device, placing a reducing agent in a carbothermic reduction area of the evaporation-carbothermic reduction device, heating the reducing agent and the selenium oxide in sequence, enabling the selenium oxide in the evaporation area to volatilize and then enter the carbothermic reduction area for reduction reaction, and collecting refined selenium from a condensation area;
the reducing agent is one or more of charcoal, coke and anthracite;
the mass ratio of the selenium oxide to the reducing agent is less than or equal to 6: 1;
the heating temperature of the reducing agent is 700-800 ℃, and the heating temperature of the selenium oxide is 280-550 ℃;
the time of the reduction reaction is 1-2 h;
the device for purifying the crude selenium by oxidation-evaporation-carbothermic reduction comprises an oxidation device and an evaporation-carbothermic reduction device;
the oxidation device comprises a heating oxidation area and a gas collecting area, and the heating oxidation area is provided with an oxygen blowing port; the inlet of the gas collecting area is communicated with the outlet of the heating oxidation area, and the gas collecting area is provided with a tail gas outlet;
the evaporation-carbon thermal reduction device comprises an evaporation area, a carbon thermal reduction area and a condensation area which are sequentially communicated from bottom to top; a separation net is arranged at the communication position of the evaporation area and the carbothermic reduction area; the condensation zone is provided with a tail gas outlet.
2. The method according to claim 1, wherein the oxidizing gas in step (1) is oxygen and/or air.
3. The method according to claim 1 or 2, wherein the oxidizing gas is introduced at a rate of 0.3 to 0.5 m/min.
4. The method according to claim 1, wherein the temperature of the oxidation reaction in the step (1) is 280-500 ℃ and the time is 1.5-2.5 h.
5. The method according to claim 1, wherein the temperature of the condensation zone in the step (2) is 150 to 300 ℃.
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