A method and device for vacuum desulfurization of electrochlorinated slag

Abstract

The present invention belongs to the technical field of precious metal smelting, and specifically relates to a method and device for vacuum desulfurization of controlled electrochlorination slag. By adopting the method disclosed in the present invention, most of the sulfur in the controlled electrochlorination slag with a mass content of 85-90% of the sulfur element can be removed, and the mass content of the sulfur element in the desulfurized controlled electrochlorination slag obtained by the present method is ≤15%. In addition, the present method can also recycle the sulfur impurities in the controlled electrochlorination slag to obtain sulfur with a purity of not less than 99%. The whole process of the present method is simple to operate, no alkaline wastewater is generated, and the whole process forms a closed-loop recovery system. After being treated by the present method, the controlled electrochlorination slag has a high direct recovery rate of platinum, palladium and gold in subsequent treatment, all of which are more than 99.9%, and there is almost no loss of platinum, palladium and gold. Moreover, vacuum distillation avoids the consumption of a large amount of desulfurization reagents, has low production costs and low labor intensity, and can also produce high-grade sulfur byproducts.

Description

Technical Field

[0001] The invention belongs to the technical field of precious metal smelting, and in particular relates to a method and device for vacuum desulfurization of electro-controlled chlorinated slag. Background Art

[0002] Controlled electrochlorination is a separation method that utilizes the difference in redox potential of different metals in a specific medium. This method controls the potential so that base metals such as copper and lead are preferentially dissolved, while precious metals such as gold and silver remain in the slag, obtaining controlled electrochlorination slag rich in precious metals, thereby achieving the purpose of separation.

[0003] The electrochlorination slag contains a large amount of sulfur, which needs to be removed before precious metal recovery, otherwise it will affect the recovery rate and quality of precious metals. At present, the main process for desulfurization of electrochlorination slag is the sodium desulfurization process, but this process has the following problems: 1. The sodium thiosulfate generated in the sodium desulfurization process of chlorination leaching tailings reacts with gold to generate gold complex ions, which enter the solution, causing gold dissolution loss, and a small amount of platinum and palladium are also lost. The longer the reaction time, the more serious the dissolution loss of gold, platinum and palladium; 2. This process requires a large amount of anhydrous sodium sulfite, with an annual processing capacity of 3,000 tons of secondary alloys, and consumes about 2,500 tons of sodium sulfite reagents each year, with a unit price of 4,800 yuan / ton, so the reagent cost is high; 3. The amount of sulfur-containing wastewater generated by the entire process is large, the treatment cost is increased, and the environmental pressure is high. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a method and device for vacuum desulfurization of electrochlorinated slag, and the present invention specifically includes the following contents:

[0005] A method for vacuum desulfurization of electro-chlorinated slag, wherein the electro-chlorinated slag is subjected to three-stage distillation, wherein the three-stage distillation comprises:

[0006] First-stage negative pressure distillation: the controlled electrochlorination slag is heated to 75-85°C at a pressure of -60kPa to -90kPa at a rate of 0.5-1°C / min to obtain first-stage dehydrated controlled electrochlorination slag with very little moisture content; the purpose of this step is to slowly evaporate and remove moisture from the material and prevent tiny materials from being taken away by the vacuum; in the present invention, the negative pressure and / or vacuum device is preferably a negative pressure furnace, which can maintain the required negative pressure by continuously pumping away the gas in the distillation system, and can continuously take away the evaporated moisture and sulfur-containing substances;

[0007] Secondary vacuum distillation: the primary dehydration and electrochlorination slag is heated to 100-120°C at a pressure of -30kPa to -40kPa at a rate of 3-4°C / min to obtain secondary desulfurization and electrochlorination slag; the purpose of this step is to allow a large amount of sulfur to melt and float on the surface of the material, which can protect the bottom precious metals and prevent them from being drawn away; on the other hand, it can accelerate the volatilization of the sulfur-containing substances on the surface to a certain extent and allow the sulfur-containing vapor to be drawn away in time;

[0008] Three-stage vacuum distillation: The secondary desulfurized electrochlorinated slag is heated to 345-355°C at a rate of 5-10°C / min under a pressure of 0.5kPa to 1kPa, and kept warm for 100-150min to obtain desulfurized electrochlorinated slag. This step can heat the sulfur to boil quickly, evaporate fully, and be sucked away by negative pressure.

[0009] Furthermore, the heating time of the first-stage negative pressure distillation is 40-50 min; and / or, the heating time of the second-stage vacuum distillation is 40-50 min; and / or, the heating time of the third-stage vacuum distillation is 20-30 min.

[0010] Furthermore, the first-stage negative pressure distillation simultaneously stirs the controlled electrochlorination slag during the heating process, and the stirring speed is controlled to be 0.4-1r / s. The purpose of stirring is to evaporate the water completely. At the same time, since the negative pressure in this step is relatively large, the stirring speed is controlled to be maintained at 0.4-1r / s, which can prevent tiny materials from being sucked away by negative pressure due to excessively fast stirring speed.

[0011] Furthermore, the secondary vacuum distillation simultaneously stirs the primary water-removing and electro-chlorination-controlled slag during the heating process, and the stirring speed is controlled to be 4-8r / s. In this step, since a large amount of sulfur melts and covers the upper layer of the material and isolates the bottom layer of the precious metal-containing material, appropriately increasing the stirring speed can accelerate the melting of sulfur without causing the fine precious metal materials to be carried away by the negative pressure.

[0012] Furthermore, the third-stage vacuum distillation simultaneously stirs the second-stage desulfurization and electrochlorination slag during the heating and insulation process, and the stirring speed is controlled to be 1-2r / s. In this step, due to the increase in temperature, the top sulfur-containing material boils rapidly, and stirring can accelerate sulfur evaporation. However, the stirring speed needs to be appropriately reduced to prevent the flying of materials and cause loss of precious metals.

[0013] Furthermore, the pH of the electro-chlorination slag is 6.5-7.5, and the water content is less than 5wt%.

[0014] Furthermore, the mass content of sulfur in the controlled electrochlorination slag is 85-90%; the mass content of sulfur in the desulfurized controlled electrochlorination slag is ≤15%.

[0015] Furthermore, the method further comprises condensing the sulfur vapor obtained by the first-stage negative pressure distillation, the second-stage vacuum distillation and the third-stage vacuum distillation through a condensing device to obtain sulfur with a purity of not less than 99%.

[0016] Furthermore, the method further includes subjecting the remaining tail gas discharged from the condensing device to secondary absorption to obtain secondary slag, and then drying the secondary slag and returning it to the primary negative pressure distillation.

[0017] A device for implementing the method for vacuum desulfurization of electrically controlled chlorinated slag, comprising a dryer, a vacuum distillation device, a condensation device, a secondary absorption device, and a secondary filtration device; the vacuum distillation device is provided with a feed port, a discharge port and a steam outlet, and the feed port is connected to the dryer; the condensation device is provided with a steam inlet and a gas outlet, and the steam inlet is connected to the steam outlet of the vacuum distillation device; the secondary absorption device is provided with an air inlet, a liquid inlet and a liquid outlet, and the air inlet is connected to the gas outlet of the condensation device; the secondary filtration device is provided with a filtrate inlet, a filtrate outlet and a slag outlet, the filtrate inlet is connected to the liquid outlet of the secondary absorption device, the filtrate outlet is connected to the liquid inlet of the secondary absorption device, and the slag outlet is connected to the dryer.

[0018] Beneficial effects of the present invention:

[0019] The controlled electrochlorination slag contains 85-90% sulfur, of which elemental sulfur accounts for 80%. The melting point of sulfur under normal pressure is 115.2°C and the boiling point is 444.6°C. The melting point and boiling point of the material change with the change of negative pressure. The greater the negative pressure, the lower the melting point and boiling point. The controlled electrochlorination slag vacuum desulfurization method disclosed by the present invention first heats the controlled electrochlorination slag to 75-85°C at a rate of 0.5-1°C / min under a pressure of -60Pa to -90kPa, and performs a first-level negative pressure distillation. This step controls the heating of the controlled electrochlorination slag at a slower rate, and cooperates with stirring at a certain speed to ensure that all materials can be evenly heated, the moisture in the materials can be slowly evaporated, and tiny materials can be prevented from being taken away by exhaust, so as to obtain a first-level desulfurized controlled electrochlorination slag with very little moisture. Then continue to heat the first-level dehydration controlled electrochlorination slag to 100-120°C at a pressure of -30kPa to -40kPa at a rate of 3-4°C / min to obtain a second-level desulfurization controlled electrochlorination slag. This step slightly increases the heating rate and stirring speed, which can make the material more evenly heated while ensuring the heating efficiency, allowing a large amount of sulfur to melt and float on the surface of the material to volatilize to a certain extent, and prevent the precious metal from being drawn away. Finally, the second-level desulfurization controlled electrochlorination slag is heated to 345-355°C at a pressure of 0.5kPa to 1kPa at a rate of 5-10°C / min, and is kept warm for 100-150min, so that the boiling sulfur is quickly and fully evaporated and drawn away by negative pressure to obtain desulfurization controlled electrochlorination slag. The role of the third step is to vaporize the sulfur element in the uniformly heated material, thereby discharging it from the controlled electrochlorination slag to achieve the purpose of desulfurization.

[0020] By adopting the method disclosed in the present invention, most of the sulfur in the controlled electrochlorination slag with a mass content of 85-90% of sulfur can be removed, and the mass content of sulfur in the desulfurized controlled electrochlorination slag obtained by the method is ≤15%. In addition, the method can also recover the sulfur impurities in the controlled electrochlorination slag to obtain sulfur with a purity of not less than 99%. The whole process of the method is simple to operate, no alkaline wastewater is generated, and the whole process forms a closed-loop recovery system. After being treated by the method, the controlled electrochlorination slag has a high direct recovery rate of platinum, palladium and gold in subsequent treatment, all of which are above 99.9%, and there is almost no loss of platinum, palladium and gold. Moreover, vacuum distillation avoids the consumption of a large amount of desulfurization reagents, has low production costs and low labor intensity, and can also produce high-grade sulfur byproducts. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a schematic diagram of the process flow of the method disclosed in the present invention. DETAILED DESCRIPTION

[0022] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments shown below do not limit the invention content described in the claims. In addition, the entire contents of the structures represented by the following embodiments are not limited to those necessary as solutions to the invention described in the claims.

[0023] Reference Figure 1 A vacuum desulfurization method for controlled electrochlorination slag, wherein the controlled electrochlorination slag is subjected to three-stage distillation, wherein the pH value of the controlled electrochlorination slag is 6.5-7.5 and the water content is less than 5wt%. The method comprises the following steps:

[0024] (1) primary negative pressure distillation: heating the controlled electrochlorination slag to 75-85° C. at a pressure of -60 kPa to -90 kPa at a rate of 0.5-1° C. / min, controlling the heating time to be 40-50 min, and stirring the controlled electrochlorination slag at the same time, controlling the stirring speed to be 0.4-1 r / s, to obtain primary dehydrated controlled electrochlorination slag;

[0025] (2) Secondary vacuum distillation: heating the primary dehydration and electro-chlorination slag to 100-120° C. at a pressure of -30 kPa to -40 kPa at a rate of 3-4° C. / min, controlling the heating time to be 40-50 min, and stirring the primary dehydration and electro-chlorination slag at a stirring speed of 4-8 r / s to obtain secondary desulfurization and electro-chlorination slag;

[0026] (3) Three-stage vacuum distillation: Under a pressure of 0.5 kPa to 1 kPa, the secondary desulfurization and controlled electrochlorination slag is heated to 345-355°C at a rate of 5-10°C / min, the heating time is controlled to be 20-30 min, and the temperature is kept for 100-150 min. At the same time, the secondary desulfurization and controlled electrochlorination slag is stirred, and the stirring speed is controlled to be 1-2 r / s to obtain desulfurization and controlled electrochlorination slag. According to the test, the mass content of sulfur in the controlled electrochlorination slag is 85-90%; the mass content of sulfur in the desulfurization and controlled electrochlorination slag is ≤15%.

[0027] (4) During the distillation, the sulfur vapor obtained by the first-stage negative pressure distillation, the second-stage vacuum distillation, and the third-stage vacuum distillation is condensed through a condensing device to obtain sulfur with a purity of not less than 99%.

[0028] (5) The remaining tail gas discharged from the condensing device is subjected to secondary absorption to obtain secondary slag, and the secondary slag is dried and returned to the first negative pressure distillation.

[0029] A device for implementing the method for vacuum desulfurization of electrically controlled chlorinated slag, comprising a dryer, a vacuum distillation device, a condensation device, a secondary absorption device, and a secondary filtration device; the vacuum distillation device is provided with a feed port, a discharge port and a steam outlet, and the feed port is connected to the dryer; the condensation device is provided with a steam inlet and a gas outlet, and the steam inlet is connected to the steam outlet of the vacuum distillation device; the secondary absorption device is provided with an air inlet, a liquid inlet and a liquid outlet, and the air inlet is connected to the gas outlet of the condensation device; the secondary filtration device is provided with a filtrate inlet, a filtrate outlet and a slag outlet, the filtrate inlet is connected to the liquid outlet of the secondary absorption device, the filtrate outlet is connected to the liquid inlet of the secondary absorption device, and the slag outlet is connected to the dryer.

[0030] Example 1

[0031] 310 kg of electrochlorination slag was washed with water to pH=7, and after drying, 200 kg of material with a water content of 0.2%, of which the sulfur content was 85%, was put into a vacuum furnace, and its vacuum degree and heating temperature were adjusted. The heating rate of the first stage was 0.5°C / min, the heating temperature was 75°C, the negative pressure was -60 kPa, the heating time was 40 min, and the stirring speed was 0.5 r / s; the heating rate of the second stage was 3°C / min, the heating temperature was 100°C, the heating time was 40 min, and the negative pressure was -30 kPa, stirring speed is 4r / s; three-stage heating heating rate is 5℃ / min, the final temperature is 345℃, the heating time is 20min, the constant temperature time is 100min, and the stirring speed is 1r / s. The added material thickness is 10cm, and the condenser collects 130kg of 99.% sulfur and 29.4kg of platinum concentrate, of which the content of platinum, palladium and gold is as high as 12.35% in total, and the sulfur content is 14.12%. Its composition is basically the same as that of the platinum concentrate obtained by sodium sulfite, and it is handed over to the next process for purification.

[0032] Example 2

[0033] 315 kg of electro-chlorination slag was washed with water to a pH of 7.5, and after drying, 204 kg of material with a water content of 0.3%, of which the sulfur content was 86.6%, was obtained. All of the material was put into a vacuum furnace, and its vacuum degree and heating temperature were adjusted. The heating rate of the first stage was 1°C / min, the heating temperature was 85°C, the negative pressure was -90 kPa, the heating time was 50 min, and the stirring speed was 1 r / s; the heating rate of the second stage was 4°C / min, the heating temperature was 120°C, the heating time was 50 min, the negative pressure was -40 kPa, and the stirring speed was 8 r / s; the heating rate of the third stage was 10°C / min, the heating temperature was 355°C, the heating time was 30 min, the constant temperature time was 150 min, and the stirring speed was 2 r / s. The thickness of the added material is 10 cm. The condenser collects 131.5 kg of 99% sulfur and 31 kg of platinum concentrate, among which the content of platinum, palladium and gold is as high as 11.98% in total, and the sulfur content is 13.97%. Its composition is basically the same as that of the platinum concentrate obtained by using sodium sulfite, and it is sent to the next process for purification.

[0034] Example 3

[0035] 301 kg of controlled electrochlorination slag was washed with water to pH=7, and after drying, 196 kg of material with a moisture content of 0.5%, of which the sulfur content was 88.1%, was put into a vacuum furnace, and its vacuum degree and heating temperature were adjusted. The heating rate of the first stage was 0.8°C / min, the heating temperature was 80°C, the negative pressure was -80kPa, and the heating time was 45min. The heating rate of the second stage was 3.5°C / min, the heating temperature was 110°C, the heating time was 45min, the negative pressure was -35kPa, the heating rate of the third stage was 8°C / min, the heating temperature was 350°C, the heating time was 25min, and the constant temperature time was 120min. The thickness of the added material was 10cm, and the condenser collected 129.8 kg of 99.% sulfur and 30.6 kg of platinum concentrate, of which the contents of platinum, palladium and gold totaled up to 13.24%, and the sulfur content was 14.28%. Its composition was basically the same as that of the platinum concentrate obtained by sodium sulfite, and it was handed over to the next process for purification.

[0036] Example 4

[0037] A vacuum desulfurization method for controlled electrochlorination slag, wherein the controlled electrochlorination slag is subjected to three-stage distillation, wherein the pH value of the controlled electrochlorination slag is 6.5 and the water content is 4.5wt%. The method comprises the following steps:

[0038] (1) primary negative pressure distillation: heating the controlled electrochlorination slag to 78-80° C. at a rate of 0.5° C. / min under a pressure of -70 kPa, controlling the heating time to be 50 min, and stirring the controlled electrochlorination slag at the same time, controlling the stirring speed to be 0.5 r / s, to obtain primary dewatered controlled electrochlorination slag;

[0039] (2) Secondary vacuum distillation: heating the primary dehydration and electro-chlorination slag to 115° C. at a rate of 3.5° C. / min under a pressure of −40 kPa, controlling the heating time to be 50 min, and stirring the primary dehydration and electro-chlorination slag at a stirring speed of 6 r / s to obtain secondary desulfurization and electro-chlorination slag;

[0040] (3) Three-stage vacuum distillation: Under a pressure of 0.8 kPa, the secondary desulfurization and controlled electrochlorination slag is heated to 350°C at a rate of 6°C / min, the heating time is controlled to be 30 minutes, and the temperature is kept for 130 minutes. At the same time, the secondary desulfurization and controlled electrochlorination slag is stirred, and the stirring speed is controlled to be 1r / s to obtain desulfurization and controlled electrochlorination slag. After testing, the mass content of sulfur in the controlled electrochlorination slag is 89.95%; the mass content of sulfur in the desulfurization and controlled electrochlorination slag is 10.03%.

[0041] (4) During the distillation, the sulfur vapor obtained by the first-stage negative pressure distillation, the second-stage vacuum distillation, and the third-stage vacuum distillation is condensed through a condensing device to obtain sulfur with a purity of 99.86%.

[0042] (5) The remaining tail gas discharged from the condensing device is subjected to secondary absorption to obtain secondary slag, and the secondary slag is dried and returned to the first negative pressure distillation.

[0043] Example 5

[0044] A vacuum desulfurization method for controlled electrochlorination slag, wherein the controlled electrochlorination slag is subjected to three-stage distillation, wherein the pH value of the controlled electrochlorination slag is 7.5 and the water content is 4.9wt%. The method comprises the following steps:

[0045] (1) primary negative pressure distillation: heating the controlled electrochlorination slag to 75° C. at a rate of 0.5° C. / min under a pressure of −90 kPa, controlling the heating time to be 40 min, and stirring the controlled electrochlorination slag at the same time, controlling the stirring speed to be 0.8 r / s, to obtain primary dehydrated controlled electrochlorination slag;

[0046] (2) Secondary vacuum distillation: heating the primary dehydration and electro-chlorination slag to 105° C. at a rate of 4° C. / min under a pressure of −40 kPa, controlling the heating time to be 40 min, and stirring the primary dehydration and electro-chlorination slag at a stirring speed of 5 r / s to obtain secondary desulfurization and electro-chlorination slag;

[0047] (3) Three-stage vacuum distillation: Under a pressure of 1 kPa, the secondary desulfurization and controlled electrochlorination slag is heated to 355°C at a rate of 5°C / min, the heating time is controlled to be 30 minutes, and the temperature is kept for 100 minutes. At the same time, the secondary desulfurization and controlled electrochlorination slag is stirred, and the stirring speed is controlled to be 1 r / s to obtain desulfurization and controlled electrochlorination slag. After testing, the mass content of sulfur in the controlled electrochlorination slag is 88.39%; the mass content of sulfur in the desulfurization and controlled electrochlorination slag is 9.84%.

[0048] (4) During the distillation, the sulfur vapor obtained by the first-stage negative pressure distillation, the second-stage vacuum distillation, and the third-stage vacuum distillation is condensed through a condensing device to obtain sulfur with a purity of 99.37%.

[0049] (5) The remaining tail gas discharged from the condensing device is subjected to secondary absorption to obtain secondary slag, and the secondary slag is dried and returned to the first negative pressure distillation.

[0050] Comparative Example 1

[0051] The difference between this comparative example and Example 5 is that no first-stage negative pressure distillation is performed, and other conditions are the same.

[0052] After testing, the purity of the sulfur obtained in this comparative example was 94.31%, and the mass content of sulfur element in the obtained desulfurized electrochlorination slag was 26.78%.

[0053] Comparative Example 2

[0054] The difference between this comparative example and Example 5 is that no secondary vacuum distillation is performed, and other conditions are the same.

[0055] After testing, the purity of the sulfur obtained in this comparative example was 90.78%, and the mass content of sulfur element in the obtained desulfurized and electro-chlorinated slag was 18.39%.

[0056] Comparative Example 3

[0057] The difference between this comparative example and Example 5 is that the pressure of the first-stage negative pressure distillation is -55 kPa, and other conditions are the same.

[0058] After testing, the purity of the sulfur obtained in this comparative example was 97.89%, and the mass content of sulfur element in the obtained desulfurized and electro-chlorinated slag was 17.36%.

[0059] Comparative Example 4

[0060] The difference between this comparative example and Example 5 is that the temperature of the first-stage negative pressure distillation is 70° C., and other conditions are the same.

[0061] After testing, the purity of the sulfur obtained in this comparative example was 96.35%, and the mass content of sulfur element in the obtained desulfurized and electro-chlorinated slag was 17.41%.

[0062] Comparative Example 5

[0063] The difference between this comparative example and Example 5 is that the pressure of the secondary vacuum distillation is -25 kPa, and other conditions are the same.

[0064] After testing, the purity of the sulfur obtained in this comparative example is 90.07%, and the mass content of sulfur element in the obtained desulfurized and electro-chlorinated slag is 20.78%.

[0065] Comparative Example 6

[0066] The difference between this comparative example and Example 5 is that the temperature of the secondary vacuum distillation is 95° C., and other conditions are the same.

[0067] After testing, the purity of the sulfur obtained in this comparative example was 89.37%, and the mass content of sulfur element in the obtained desulfurized and electro-chlorinated slag was 19.21%.

[0068] Comparative Example 7

[0069] The difference between this comparative example and Example 5 is that the heating rate of the secondary vacuum distillation is 5° C. / min, and other conditions are the same.

[0070] After testing, the purity of the sulfur obtained in this comparative example was 97.56%, and the mass content of sulfur element in the obtained desulfurized electrochlorination slag was 17.25%.

[0071] Comparative Example 8

[0072] The difference between this comparative example and Example 5 is that the heating rate of the secondary vacuum distillation is 2° C. / min, and other conditions are the same.

[0073] After testing, the purity of the sulfur obtained in this comparative example was 98.03%, and the mass content of sulfur element in the obtained desulfurized and electro-chlorinated slag was 16.51%.

[0074] Comparative Example 9

[0075] The difference between this comparative example and Example 5 is that the heating rate of the three-stage vacuum distillation is 15° C. / min, and other conditions are the same.

[0076] After testing, the purity of the sulfur obtained in this comparative example was 98.81%, and the mass content of sulfur element in the obtained desulfurized and electro-chlorinated slag was 16.91%.

[0077] Comparative Example 10

[0078] The difference between this comparative example and Example 5 is that the temperature of the third-stage vacuum distillation is 340° C., and other conditions are the same.

[0079] After testing, the purity of the sulfur obtained in this comparative example was 98.10%, and the mass content of sulfur element in the obtained desulfurized and electro-chlorinated slag was 18.34%.

[0080] Comparative Example 11

[0081] The difference between this comparative example and Example 5 is that the pressure of the third-stage vacuum distillation is 0.4 kPa, and other conditions are the same.

[0082] After testing, the purity of the sulfur obtained in this comparative example was 97.54%, and the mass content of sulfur element in the obtained desulfurized and electro-chlorinated slag was 19.38%.

[0083] Unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0084] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for vacuum desulfurization of electrochlorinated slag, characterized in that: The electrochlorination slag is subjected to three-stage distillation, and the three-stage distillation comprises: First-stage negative pressure distillation: heating the controlled electrochlorination slag to 75-85° C. at a pressure of -60 kPa to -90 kPa at a rate of 0.5-1° C. / min to obtain first-stage dehydrated controlled electrochlorination slag; Secondary vacuum distillation: heating the primary dehydration and electro-chlorination slag to 100-120° C. at a pressure of -30 kPa to -40 kPa at a rate of 3-4° C. / min to obtain secondary desulfurization and electro-chlorination slag; Three-stage vacuum distillation: the secondary desulfurized and electro-chlorinated slag is heated to 345-355°C at a rate of 5-10°C / min under a pressure of 0.5 kPa to 1 kPa, and kept warm for 100-150 minutes to obtain the desulfurized and electro-chlorinated slag.

2. A method for vacuum desulfurization of electrochlorinated slag according to claim 1, characterized in that: The heating time of the first-stage negative pressure distillation is 40-50 min; and / or, the heating time of the second-stage vacuum distillation is 40-50 min; and / or, the heating time of the third-stage vacuum distillation is 20-30 min.

3. A method for vacuum desulfurization of electrochlorinated slag according to claim 1, characterized in that: The first-stage negative pressure distillation simultaneously stirs the controlled electrochlorination slag during the heating process, and the stirring speed is controlled to be 0.4-1r / s.

4. A method for vacuum desulfurization of electrochlorinated slag according to claim 3, characterized in that: The secondary vacuum distillation simultaneously stirs the primary water-removing and electro-chlorination-controlled slag during the heating process, and the stirring speed is controlled to be 4-8 r / s.

5. A method for vacuum desulfurization of electrochlorinated slag according to claim 4, characterized in that: The third-stage vacuum distillation simultaneously stirs the second-stage desulfurization and electrochlorination slag during the heating and heat preservation process, and the stirring speed is controlled to be 1-2r / s.

6. A method for vacuum desulfurization of electrochlorinated slag according to claim 1, characterized in that: The pH of the electro-chlorination slag is 6.5-7.5, and the water content is less than 5wt%.

7. A method for vacuum desulfurization of electrochlorinated slag according to claim 1, characterized in that: The mass content of sulfur in the controlled electrochlorination slag is 85-90%; the mass content of sulfur in the desulfurized controlled electrochlorination slag is ≤15%.

8. A method for vacuum desulfurization of electrochlorinated slag according to claim 1, characterized in that: The method also includes condensing the sulfur vapor obtained by the first-stage negative pressure distillation, the second-stage vacuum distillation and the third-stage vacuum distillation through a condensing device to obtain sulfur with a purity of not less than 99%.

9. A method for vacuum desulfurization of electrochlorinated slag according to claim 8, characterized in that: The method also includes subjecting the remaining tail gas discharged from the condensing device to secondary absorption to obtain secondary slag, and then drying the secondary slag and returning it to the first-level negative pressure distillation.

10. A device for implementing the method for vacuum desulfurization of electrochlorinated slag according to any one of claims 1 to 9, characterized in that: It includes a dryer, a vacuum distillation device, a condensing device, a secondary absorption device, and a secondary filtration device; The vacuum distillation device is provided with a feed inlet, a discharge port and a steam outlet, and the feed inlet is connected to the dryer; The condensing device is provided with a steam inlet and a gas outlet, and the steam inlet is connected to the steam outlet of the vacuum distillation device; The secondary absorption device is provided with an air inlet, a liquid inlet and a liquid outlet, and the air inlet is connected to the gas outlet of the condensing device; The secondary filtering device is provided with a filtrate inlet, a filtrate outlet and a residue outlet, the filtrate inlet is connected to the liquid outlet of the secondary absorption device, the filtrate outlet is connected to the liquid inlet of the secondary absorption device, and the residue outlet is connected to the dryer.

Images