Method for impurity removal and water balance control of vanadium extraction tailing washing leaching solution

Abstract

The application discloses a method for impurity removal and water balance control of vanadium extraction tailing washing leaching liquid, which comprises the following steps: solid-liquid separation is performed on the leaching slurry, at least three-stage countercurrent washing is performed on the obtained solid, and leaching liquid is obtained; a silicon removal agent is added in the leaching liquid, silicon removal is performed, and the obtained silicon removal slurry is allowed to stand and settle; the supernatant is introduced into a silicon removal liquid tank, the lower silicon residue thick slurry is introduced into a buffer tank, pressure filtration is performed to realize solid-liquid separation, the filtrate is introduced into the silicon removal liquid tank, and solid residue is obtained; after the solid residue is added with water to realize beating and washing, pressure filtration is performed to realize solid-liquid separation, the filtrate is introduced into the silicon removal liquid tank, and final solid residue is obtained; and the liquid in the silicon removal liquid tank is cooled, and the upper liquid is introduced into an ammonia absorption tower. The method disclosed by the application has less water removal, less new water can be introduced to maintain water balance, effectively solves the residue washing problem, improves the washing effect, reduces vanadium loss, maintains the composition of each solution and system water balance.

Description

Technical Field

[0001] This invention relates to the field of vanadium extraction tailings post-treatment technology, specifically to a method for removing impurities and controlling the water balance of vanadium extraction tailings washing leachate. Background Technology

[0002] Vanadium extraction from vanadium slag is currently the most mainstream vanadium extraction technology, mainly including processes such as sodium roasting-water leaching, calcification roasting-acid leaching, and blank roasting / calcification roasting-carbonate leaching. Compared to other vanadium extraction processes, the blank roasting / calcification roasting-carbonate leaching process requires treatment of the vanadium precipitation wastewater or the addition of large amounts of fresh water. For example, the vanadium precipitation wastewater from calcification roasting-acid leaching needs special treatment and pH adjustment before it can be returned for residue washing. This process is not only complex but also wastes a large amount of water resources and introduces other substances that cause new pollution, making it extremely unfriendly to water resources and environmental protection.

[0003] Chinese patent application 201210150237.9 discloses a method for preparing ammonium metavanadate. This method involves contacting a sodium vanadate solution with an ammonium salt under acidic conditions, precipitating and separating the resulting product to obtain solid ammonium polyvanadate; then contacting the solid ammonium polyvanadate with water and an ammonium vanadate restructuring agent to convert the polyvanadate into ammonium metavanadate, and finally separating the resulting product to obtain an ammonium metavanadate solution. This invention not only introduces an ammonium salt but also wastes a significant amount of water during the washing of the solid ammonium polyvanadate. Summary of the Invention

[0004] The purpose of this invention is to provide a method for impurity removal and water balance control of vanadium extraction tailings washing leaching solution. This method is mainly for the blank roasting / calcification roasting-carbonation leaching vanadium extraction process, where the mass ratio of external calcium oxide to vanadium slag is no greater than 0.8 (CaO / V2O5). The supernatant of vanadium precipitation is used as the leaching agent, and a small amount of sodium bicarbonate / sodium carbonate is added under a certain liquid-solid ratio. Leaching is carried out under high temperature conditions by heating. The leaching slurry is filtered while hot, washed with hot water to reduce the viscosity of the residue and improve the filtration rate. Limited wash water is used for multiple countercurrent washings to improve the washing effect. The amount of wash water used in each stage is strictly controlled to ensure the water balance of the system.

[0005] The entire system removes little water, and to maintain water balance, little new water can be introduced. This method can effectively solve the problem of residue washing, improve washing effect, reduce vanadium loss, and maintain the water balance of each solution component and the system.

[0006] To achieve the above-mentioned objectives, this invention provides a method for removing impurities and controlling the water balance of vanadium extraction tailings washing leachate, comprising the following steps: Step (1): After leaching, the leachate slurry is subjected to solid-liquid separation at a certain temperature, and the solid obtained by separation is subjected to at least three stages of countercurrent washing to obtain leachate; Step (2): Add desiliconizing agent to the leachate, stir to remove silicon and obtain desiliconized slurry, and let the desiliconized slurry settle. Step (3): After settling, the supernatant is introduced into the desiliconization tank, the lower silicon slag slurry is introduced into the buffer tank, and solid-liquid separation is carried out by plate and frame filter press. The filtrate is introduced into the desiliconization tank to obtain solid residue. Step (4): After adding water to the solid residue for pulping and washing, the solid residue is separated by plate and frame filter press again. The filtrate is introduced into the desiliconization tank to obtain the final solid residue. Step (5): After the liquid in the desiliconization tank is cooled, the upper layer of liquid enters the ammonia absorption tower to absorb ammonia-containing gas.

[0007] In this invention, step (1) involves at least three stages of countercurrent washing, namely, the first stage wash water is the second stage filtrate from the previous round of residue washing, the first stage wash filtrate enters the leachate, the second stage wash water is the third stage filtrate from the previous round of residue washing, the second stage wash filtrate is used as the first stage wash water, the third stage wash water is the fourth stage filtrate or clean water from the previous round of residue washing, part of the third stage wash filtrate is used as the second stage wash water, and part is used for washing the silicon slag, the fourth stage wash water is the fifth stage filtrate or clean water from the previous round of residue washing, the fourth stage wash filtrate is used as the third stage wash water..., that is, the last stage wash water is clean water, and only the third stage filtrate is used in two parts; preferably, the number of washing cycles in the multi-stage countercurrent washing is 3 to 7 times.

[0008] To further explain, in step (1), the amount of first-stage washing water is the difference between the supernatant and the leachate in this round, that is, the amount of leachate replenished is equal to the amount (volume) of supernatant. Second-stage washing water replenishes the amount of first-stage washing water consumed, third-stage washing water replenishes the amount of second-stage washing water consumed, fourth-stage washing water or clean water replenishes the amount of third-stage washing water and the amount of washing water used for removing silicon slag pulping, fifth-stage washing water or clean water replenishes the amount of fourth-stage washing water consumed, and so on. According to the method for removing impurities and controlling water balance of vanadium extraction tailings washing leachate according to the present invention, preferably, in step (1), the temperature for solid-liquid separation of the leachate slurry is 80℃~95℃.

[0009] According to the method for removing impurities and controlling water balance in the washing leachate of vanadium extraction tailings of the present invention, preferably, in step (1), the solid-liquid separation adopts a vacuum negative pressure filtration device, the vacuum degree is controlled at -0.07MPa~-0.03MPa, and the water content of the obtained solid is 20~40wt%.

[0010] According to the method for removing impurities and controlling water balance in the washing leachate of vanadium extraction tailings according to the present invention, preferably, in step (1), the washing water temperature of at least three-stage countercurrent washing is 60℃~80℃.

[0011] According to the method for removing impurities and controlling water balance in the washing leachate of vanadium extraction tailings of the present invention, preferably, in step (2), the desiliconizing agent is sodium aluminate, which is added at a molar ratio of Al to Si of 0.7 to 1.2.

[0012] In this invention, in step (2), the silica slurry is allowed to settle in a settling tank for 24 hours to 72 hours.

[0013] According to the method for removing impurities and controlling water balance in the washing leachate of vanadium extraction tailings of the present invention, preferably, in step (2), the silicon removal temperature is 30℃~80℃ and the silicon removal time is 15min~60min.

[0014] According to the method for removing impurities and controlling water balance of vanadium tailings washing leachate according to the present invention, preferably, in step (3), the supernatant accounts for 20% to 35% of the total volume of the desiliconized slurry, and the water content of the solid residue is 60% to 90%.

[0015] According to the method for removing impurities and controlling water balance of vanadium extraction tailings washing leachate according to the present invention, preferably, in step (4), the ratio of water added to solid residue volume is 1.0~1.5, and the added water is the three-stage washing filtrate in step (1).

[0016] According to the method for removing impurities and controlling water balance of vanadium tailings washing leachate according to the present invention, preferably, in step (4), the washing temperature is 30℃~80℃, the washing time is 15min~60min, and the water content of the final solid residue is 60~90wt%.

[0017] According to the method for removing impurities and controlling water balance of vanadium tailings washing leachate according to the present invention, preferably, in step (5), the temperature of the upper liquid entering the ammonia absorption tower is 20℃~45℃, and the volume of the upper liquid accounts for 80%~90% of the total volume of the desiliconizing liquid.

[0018] As a specific embodiment of the present invention, a method for removing impurities and controlling the water balance of vanadium extraction tailings washing leachate includes the following steps: (1) After leaching, the leaching slurry is separated into solid and liquid by filtration. The filtration temperature is controlled at 80℃~95℃. Vacuum negative pressure filtration equipment is used for filtration. The vacuum degree is controlled at -0.07MPa~-0.03MPa. If the vacuum is too large, it will increase the ammonium loss. If it is too small, it will reduce the filtration efficiency and increase the ammonium loss. The water content of the solid obtained by separation is controlled at 20~40wt%. Then, the solid obtained by separation is washed by multi-stage countercurrent. The number of washing times can be 3~7 times. The washing water temperature is 60℃~80℃. The first washing water volume is the difference between the supernatant and the leaching liquid in this round. That is, the amount of leaching liquid is made up to equal the amount of supernatant (volume). The second washing water makes up for the consumption of the first washing water. The third washing water makes up for the consumption of the second washing water. The fourth washing water or clean water makes up for the consumption of the third washing water and the solid pulping and washing. The fifth washing water or clean water makes up for the consumption of the fourth washing water. The process is repeated as above. (2) The leachate is desiliconized using sodium aluminate. Sodium aluminate is added at an Al / Si ratio of 0.7 to 1.2 (molar ratio). The desiliconization temperature is 30°C to 80°C, and the desiliconization time is 15 min to 60 min. After the desiliconization operation is completed, the desiliconized slurry is placed in a settling tank and allowed to stand for 24 h to 72 h. (3) The outlet of the desiliconized liquid is located at 20%~35% of the volume of the desiliconized slurry settling tank (i.e., 65%~80% is supernatant). The supernatant enters the desiliconized liquid tank. The water content of the solid residue after the plate and frame filter press of the thick slurry at the bottom of the desiliconized slurry settling tank is 60~90wt%. The filtrate enters the desiliconized liquid tank. (4) Solid residue is pulped and washed. The washing water volume is 1.0~1.5 volumes of solid residue. The washing water comes from the three-stage washing filtrate in step (1). The washing temperature is 30℃~80℃ and the washing time is 15min~60min. The washing water and filtrate enter the desiliconization tank and are filtered again by plate and frame filter press to obtain the final solid residue with a water content of 60~90wt%. (5) The outlet of the desilicon liquid is located at 10%~20% of the volume of the desilicon liquid tank slurry (i.e., 80%~90% is the desilicon liquid after desiliconization). The bottom slag of the desilicon liquid tank enters the desilicon slurry settling tank for further settling. The desilicon liquid uses the supernatant for heat exchange and controls the temperature of the ammonia absorption tower to be 20℃~45℃.

[0019] The beneficial effects of this invention are: This invention primarily targets the blank roasting / calcification roasting-carbonation leaching process for vanadium extraction. The vanadium slag is mixed with calcium oxide at a mass ratio of CaO / V₂O₅ not exceeding 0.8. The supernatant from the vanadium precipitation is used as the leaching agent. Under a specific liquid-to-solid ratio, a small amount of sodium bicarbonate / sodium carbonate is added. Leaching is performed at high temperatures. The leached slurry is filtered while hot, washed with hot water to reduce residual viscosity and increase the filtration rate. Multiple countercurrent washes with limited wash water enhance the washing effect. Strict control of the amount of wash water used at each stage ensures system water balance.

[0020] The entire system removes little water, and to maintain water balance, little new water can be introduced. This method can effectively solve the problem of residue washing, improve washing effect, reduce vanadium loss, and maintain the water balance of each solution component and the system. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples.

[0022] It should be noted that all uses of "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two entities or parameters with the same name but different names. It is clear that "first" and "second" are only for the convenience of expression and should not be construed as limiting the embodiments of the present invention. Subsequent embodiments will not explain this in detail.

[0023] In both Embodiment 1 and Embodiment 2 of this invention, the leaching slurry was obtained by leaching 10m of supernatant with 5000kg of molten material.

[0024] Example 1 Example 1 provides a method for removing impurities and controlling the water balance of vanadium extraction tailings washing leachate, comprising the following steps: (1) After leaching, the leachate slurry was subjected to solid-liquid separation and washing while still hot. The leachate slurry was filtered using a vacuum negative pressure filtration device. The filtration temperature was controlled at 90℃ and the vacuum degree was -0.05MPa. Too high a vacuum degree would increase ammonium loss, while too low a vacuum degree would decrease filtration efficiency and increase ammonium loss. The water content of the separated solid was 30%, and 6.86 ml of leachate was obtained. The separated solid was washed countercurrently, with the number of washes controlled at 4 times and the washing water temperature at 70℃. The first-stage wash water volume (3.14 m³) is the difference between the supernatant and the leachate in this round. That is, the amount of leachate replenished by the first-stage filtrate is equal to the amount of supernatant (10 m³ round). The second-stage wash water (3.14 m³) replenishes the consumption of the first-stage wash water. The third-stage wash water (3.14 m³) replenishes the consumption of the second-stage wash water. The fourth-stage wash water (3.50 m³) replenishes the consumption of the third-stage wash water and solid pulping and washing. The fifth-stage fresh water (3.50 m³) replenishes the consumption of the fourth-stage wash water. (2) Add sodium aluminate to the leachate to remove silicon. Add desiliconizing agent (12.81L of 160g / L sodium aluminate, 0.07g / L of silicon in the leachate) at Al / Si=1.0 (molar ratio). The desiliconization temperature is 80℃ and the desiliconization time is 30min. After the desiliconization operation is completed, the desiliconized slurry is put into the desiliconized slurry settling tank and left to stand for 24h. (3) The desilicon liquid outlet of the desilicon slurry settling tank is located at 30% of the slurry volume of the desilicon slurry settling tank (i.e., 70% is desilicon liquid). The desilicon liquid enters the desilicon liquid tank. The concentrated slurry (30%) at the bottom of the desilicon slurry settling tank is filtered by plate and frame filter press to obtain solid residue with a water content of 75wt%. The filtrate enters the desilicon liquid tank. (4) The solid residue is pulped and washed. The amount of washing water (360L) is 1.0 volume of solid residue. The washing water comes from the three-stage washing filtrate in step (1). The washing temperature is 70℃ and the washing time is 15min. After plate and frame filtration again, the water content of the final solid residue is 75wt%. The washing water and filtrate enter the desiliconized liquid tank. (5) The outlet of the desilicon liquid tank is located at 10% of the volume of the slurry in the desilicon liquid tank after desiliconization (i.e., 90% is the desilicon liquid after desiliconization, and the bottom slag (10%) of the desilicon liquid tank enters the desilicon slurry settling tank for further settling. The desilicon liquid uses the supernatant for heat exchange and controls the temperature of the ammonia absorption tower to be 30℃.

[0025] Example 2 Example 2 provides a method for removing impurities and controlling the water balance of vanadium extraction tailings washing leachate, comprising the following steps: (1) After leaching, the leachate slurry is separated into solids and washed while still hot. The leachate slurry is filtered using a vacuum negative pressure filtration device. The filtration temperature is controlled at 80℃ and the vacuum degree is -0.06MPa. If the vacuum degree is too high, it will increase the ammonium loss. If it is too low, it will reduce the filtration efficiency and increase the ammonium loss. The water content of the separated solid is 25%, and 7.33m of leachate is obtained. The separated solid is washed countercurrently, and the number of washings is controlled at 3 times. The washing water temperature is 80℃. The first-stage washing water volume (2.67m volume) is the difference between the supernatant and the leachate in this round. That is, the first-stage filtrate enters the leachate to make up the leachate volume equal to the supernatant volume (10m round). The second-stage washing water (2.67m water) makes up the consumption of the first-stage washing water. The third-stage washing water (2.67m washing) makes up the consumption of the second-stage washing water. The fourth-stage fresh water (3.32m washing) makes up the consumption of the third-stage washing water and the solid pulping and washing. (2) Add sodium aluminate to the leachate to remove silicon. Add desiliconizing agent (17.57L of 160g / L sodium aluminate, 0.08g / L of silicon in the leachate) at Al / Si=1.2 (molar ratio). The desiliconization temperature is 70℃ and the desiliconization time is 15min. After the desiliconization operation is completed, the desiliconized slurry is put into the desiliconized slurry settling tank and left to stand for 72h. (3) The outlet of the desiliconized liquid in the desiliconized slurry settling tank is located at 30% of the volume of the desiliconized slurry settling tank (i.e., 70% is the desiliconized liquid). The desiliconized liquid enters the desiliconized liquid tank. The concentrated slurry (30%) at the bottom of the desiliconized slurry settling tank is filtered by plate and frame filter press to obtain solid residue with a water content of 90wt%. The filtrate enters the desiliconized liquid tank. (4) The solid residue is pulped and washed. The amount of washing water (650L) is 1.5 volumes of solid residue. The washing water comes from the three-stage washing filtrate in step (1). The washing temperature is 60℃ and the washing time is 15min. After plate and frame filtration again, the final solid residue has a water content of 90wt%. The washing water and filtrate enter the desiliconization tank. (5) The outlet of the desilicon liquid in the desilicon liquid tank is located at 10% of the volume of the desilicon liquid tank slurry (i.e., 90% is desilicon liquid, and the bottom slag (10%) of the desilicon liquid tank enters the desilicon slurry settling tank for further settling. The desilicon liquid uses the supernatant for heat exchange and controls the temperature of the ammonia absorption tower to be 20℃.

[0026] It should be noted that the components or steps in the above embodiments can be interchanged, substituted, added, or deleted. Therefore, the combinations formed by these reasonable permutations and transformations should also fall within the protection scope of this invention, and the protection scope of this invention should not be limited to the above embodiments.

[0027] The above are exemplary embodiments disclosed in this invention. The order of the disclosed embodiments is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. However, it should be noted that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the disclosed embodiments of this invention (including the claims) is limited to these examples. Various changes and modifications can be made without departing from the scope defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular.

[0028] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of the different aspects of the invention as described above exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for removing impurities and controlling the water balance of vanadium extraction tailings washing leachate, characterized in that, The steps include the following: Step (1): After leaching, the leachate slurry is subjected to solid-liquid separation at a certain temperature, and the solid obtained by separation is subjected to at least three countercurrent washings to obtain leachate; Step (2): Add desiliconizing agent to the leachate, stir to remove silicon and obtain desiliconized slurry, and let the desiliconized slurry settle. Step (3): After settling, the supernatant is introduced into the desiliconization tank, the lower silicon slag slurry is introduced into the buffer tank, and solid-liquid separation is carried out by plate and frame filter press. The filtrate is introduced into the desiliconization tank to obtain solid residue. Step (4): After adding water to the solid residue for pulping and washing, the solid residue is separated by plate and frame filter press again. The filtrate is introduced into the desiliconization tank to obtain the final solid residue. Step (5): After the liquid in the desiliconization tank is cooled, the upper layer of liquid enters the ammonia absorption tower to absorb ammonia-containing gas.

2. The method for removing impurities and controlling the water balance of vanadium extraction tailings washing leachate according to claim 1, characterized in that, In step (1), the temperature for solid-liquid separation of the leachate slurry is 80℃~95℃.

3. The method for removing impurities and controlling the water balance of vanadium extraction tailings washing leachate according to claim 2, characterized in that, In step (1), solid-liquid separation is performed using a vacuum negative pressure filtration device, with the vacuum degree controlled at -0.07MPa to -0.03MPa, and the obtained solid has a water content of 20 to 40wt%.

4. The method for removing impurities and controlling the water balance of vanadium extraction tailings washing leachate according to claim 1, characterized in that, In step (1), the washing water temperature for at least three stages of countercurrent washing is 60℃~80℃.

5. The method for removing impurities and controlling the water balance of vanadium extraction tailings washing leachate according to claim 4, characterized in that, In step (2), the silicon remover is sodium aluminate, which is added at a molar ratio of Al to Si of 0.7 to 1.

2.

6. The method for removing impurities and controlling the water balance of vanadium extraction tailings washing leachate according to claim 5, characterized in that, In step (2), the silicon removal temperature is 30℃~80℃ and the silicon removal time is 15min~60min.

7. The method for removing impurities and controlling the water balance of vanadium extraction tailings washing leachate according to claim 1, characterized in that, In step (3), the supernatant accounts for 20% to 35% of the total volume of the desiliconized slurry, and the water content of the solid residue is 60 to 90 wt%.

8. The method for removing impurities and controlling the water balance of vanadium extraction tailings washing leachate according to claim 7, characterized in that, In step (4), the ratio of water volume to solid residue volume is 1.0 to 1.5, and the water added is the tertiary washing filtrate from step (1).

9. A method for removing impurities and controlling the water balance of vanadium extraction tailings washing leachate according to any one of claims 1-8, characterized in that, In step (4), the washing temperature is 30℃~80℃, the washing time is 15min~60min, and the final moisture content of the solid residue is 60~90wt%.

10. The method for removing impurities and controlling the water balance of vanadium extraction tailings washing leachate according to claim 9, characterized in that, In step (5), the temperature of the upper liquid entering the ammonia absorption tower is 20℃~45℃, and the volume of the upper liquid accounts for 80%~90% of the total volume of the desiliconizing liquid.