Vanadium-containing mother liquor wastewater recycling process

Abstract

The invention relates to the technical field of vanadium recovery, in particular to a vanadium-containing mother liquor wastewater recycling process. Comprising the following steps: directly blending the vanadium-containing mother liquor wastewater generated by oxidizing, hydrolyzing and precipitating vanadium in the process of extracting vanadium from the chlorination-process titanium dioxide waste acid into the chlorination-process titanium dioxide waste acid to circularly extract vanadium. According to the method, pentavalent vanadium in the vanadium-containing mother liquor wastewater is reduced into tetravalent vanadium by utilizing a large amount of ferrous ions in the titanium dioxide waste acid feed liquid, then the tetravalent vanadium and the titanium dioxide waste acid are neutralized, extracted and recycled, reduction is carried out by utilizing the waste acid, extra agents such as a precipitator or a reducing agent do not need to be used, the agent cost is saved, and the energy consumption is reduced. Meanwhile, the vanadium-containing enriched slag does not need to be subjected to complex purification treatment, the process is simple, the cost is low, and the recovery rate of vanadium can be increased.

Description

Technical Field

[0001] The invention relates to the technical field of vanadium recovery, and in particular to a vanadium-containing mother liquor wastewater recycling process. Background Art

[0002] At present, the process of extracting and recovering vanadium from waste acid of titanium dioxide produced by the chloride process usually includes the steps of oxidative hydrolysis and vanadium precipitation, after which solid-liquid separation is performed to obtain a precipitated product and vanadium-containing mother liquor wastewater; direct discharge of the vanadium-containing mother liquor wastewater will cause a waste of vanadium resources, resulting in a low vanadium recovery rate in waste acid of titanium dioxide produced by the chloride process, and will also cause environmental pollution.

[0003] The current treatment process mainly involves adding a precipitant to the vanadium-containing mother liquor wastewater to precipitate and separate the vanadium from the wastewater, discharging the wastewater after precipitation and separation by the precipitant, and making vanadium-containing enriched slag. This recycling method not only consumes a large amount of precipitant, but also produces a high impurity content in the vanadium-containing enriched slag. The subsequent processing into high-purity vanadium is costly, the overall process is complicated, and a large amount of wastewater is discharged.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a recycling process for vanadium-containing mother liquor wastewater to solve the technical problems in the prior art that direct discharge of vanadium-containing mother liquor wastewater leads to waste of vanadium resources and causes environmental pollution, and the technical problems that traditional treatment of vanadium-containing mother liquor wastewater by adding precipitants requires consumption of a large amount of precipitants, and the process is complex and costly.

[0006] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0007] A vanadium-containing mother liquor wastewater recycling process comprises the following steps:

[0008] The vanadium-containing mother liquor wastewater produced by oxidative hydrolysis and vanadium precipitation in the process of extracting vanadium from titanium dioxide waste acid by the chloride process is directly mixed with the titanium dioxide waste acid by the chloride process for cyclic extraction and vanadium extraction.

[0009] Preferably, the volume ratio of the vanadium-containing mother liquor wastewater to the chloride process titanium dioxide waste acid is 1:1-80.

[0010] Preferably, the vanadium-containing mother liquor wastewater recycling process specifically comprises the following steps:

[0011] S1. blending the vanadium-containing mother liquor wastewater into the chloride process titanium dioxide waste acid;

[0012] S2. The blended liquid is neutralized to a pH of 0.5-1.5, and after precipitation of the liquid, the clarified liquid is separated;

[0013] S3. Adding an organic phase to the clarified liquid for extraction to obtain a vanadium-rich organic phase;

[0014] S4. stripping the vanadium-rich organic phase with a stripping agent to obtain a vanadium-rich stripping solution, and transferring vanadium from the organic phase to the aqueous phase;

[0015] S5. Add an oxidant to the vanadium-rich stripping solution to carry out oxidative hydrolysis and precipitation of vanadium, and the vanadium-containing mother liquor wastewater obtained by solid-liquid separation is circulated to step S1 for blending.

[0016] Preferably, in step S2, the alkali used in the neutralization liquid preparation process includes at least one of sodium hydroxide, sodium carbonate and calcium carbonate.

[0017] Preferably, in step S3, the organic phase comprises, by volume percentage, 10%-30% of an extractant, 5%-10% of a modifier and the remainder of solvent oil.

[0018] Preferably, the extractant comprises at least one of P204, P507, C272, and P350;

[0019] And / or, the modifier includes TBP and / or isooctyl alcohol.

[0020] Preferably, in step S3, the extraction ratio O / A is 1:2-4.

[0021] Preferably, in step S4, the stripping agent includes sulfuric acid and / or hydrochloric acid.

[0022] Preferably, in step S4, the phase ratio O / A of the stripping is 2-6:1.

[0023] Preferably, in step S5, the oxidant includes at least one of sodium chlorate, sodium hypochlorite, sodium chlorite and hydrogen peroxide.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention mixes the vanadium-containing mother liquor wastewater generated by oxidative hydrolysis vanadium precipitation into the chlorination process titanium dioxide waste acid, uses a large amount of ferrous ions in the feed liquid to reduce the pentavalent vanadium in the vanadium-containing mother liquor wastewater to tetravalent vanadium, and then recovers it together with the vanadium in the titanium dioxide waste acid through neutralization extraction, and uses the waste acid for reduction, without the need to use additional precipitants or reducing agents, thus saving the cost of the agents, and also without the need to perform complex purification treatment on the vanadium-containing enriched slag, which not only greatly reduces the cost, but also greatly improves the overall recovery rate of vanadium (the recovery rate of vanadium in the wastewater is above 99.5%) through the process of front-end mixing, and the recycling of the vanadium-containing wastewater solves the problem of discharging a large amount of wastewater, and the present invention belongs to a green environmental protection process. At present, in the process of extracting vanadium from the titanium dioxide waste acid by the chlorination process, the output of the vanadium-containing mother liquor wastewater is about 1 / 30 of the titanium dioxide waste acid, and the vanadium-containing mother liquor wastewater can be fully reused. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic diagram of a process flow of a vanadium-containing mother liquor wastewater recycling process provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0028] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be appreciated by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work, all belong to the scope of protection of the present invention. If specific conditions are not indicated in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0029] like Figure 1 As shown, the present invention provides a vanadium-containing mother liquor wastewater recycling process, comprising the following steps:

[0030] The vanadium-containing mother liquor wastewater produced by oxidative hydrolysis and vanadium precipitation in the process of extracting vanadium from titanium dioxide waste acid by the chloride process is directly mixed with the titanium dioxide waste acid by the chloride process for cyclic extraction and vanadium extraction.

[0031] The present invention innovates the process section to solve the problems of low vanadium recovery rate and vanadium-containing wastewater discharge. The pentavalent vanadium-containing mother liquor wastewater after oxidation is directly mixed with the chlorination process titanium dioxide waste acid. The pentavalent vanadium in the vanadium-containing mother liquor wastewater is reduced by using a large amount of ferrous ions in the waste acid solution. After reduction, the feed liquid is neutralized to a suitable pH to extract and enrich vanadium. The loaded organic phase is stripped, oxidized and hydrolyzed to generate red vanadium (sodium polyvanadate) and vanadium-containing mother liquor wastewater. The vanadium-containing mother liquor wastewater is returned to the chlorination process titanium dioxide waste acid for blending and recovery. More than 99.7% of vanadium in the vanadium-containing mother liquor wastewater can be extracted and recovered. The vanadium-containing mother liquor wastewater is recycled in the process section, realizing the reuse of vanadium-containing wastewater and solving the environmental protection problem. At the same time, it also solves the problems of high reagent cost, high impurity content of vanadium-containing enriched slag, high purification cost and complex process in the traditional method of using a precipitant to treat vanadium-containing mother liquor wastewater.

[0032] In some specific embodiments of the present invention, when the vanadium-containing mother liquor wastewater is added to the chlorination process titanium dioxide waste acid, the volume ratio of the vanadium-containing mother liquor wastewater to the chlorination process titanium dioxide waste acid is 1:1-80, for example, it can be any point value among 1:1, 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80 or a range value consisting of any two point values.

[0033] If the proportion of vanadium-containing mother liquor wastewater is too large, the ferrous iron in the waste acid cannot completely reduce pentavalent vanadium, and the vanadium recovery rate in the wastewater is low; if the proportion of vanadium-containing mother liquor wastewater is too small, the recycling rate of vanadium-containing mother liquor wastewater is low, and the vanadium-containing wastewater cannot be completely consumed.

[0034] In some specific embodiments of the present invention, the vanadium-containing mother liquor wastewater recycling process specifically comprises the following steps:

[0035] S1. Blending: blending the vanadium-containing mother liquor wastewater into the chloride process titanium dioxide waste acid;

[0036] S2. Neutralization: The feed solution after blending in step S1 is neutralized and the pH of the neutralized feed solution is brought to 0.5-1.5. After the feed solution precipitates, the clarified feed solution is separated;

[0037] S3 extraction: adding an organic phase to the clarified liquid separated in step S2 for extraction to obtain a vanadium-rich organic phase;

[0038] S4. Stripping: stripping the vanadium-rich organic phase with a stripping agent to obtain a vanadium-rich stripping solution, and transferring vanadium from the organic phase to the aqueous phase;

[0039] S5. Oxidative hydrolysis vanadium precipitation: adding an oxidant to the vanadium-rich stripping solution to oxidatively hydrolyze vanadium precipitation, and the vanadium-containing mother liquor wastewater obtained by solid-liquid separation is circulated to step S1 for blending.

[0040] In some specific embodiments of the present invention, in step S2, before neutralization and liquid preparation, the mixed liquid is also preheated to 50-60°C, for example, any point value among 50°C, 52°C, 55°C, 58°C, 60°C or a range value consisting of any two point values.

[0041] In some specific embodiments of the present invention, in step S2, the alkali used in the neutralization liquid preparation process includes at least one of sodium hydroxide, sodium carbonate, and calcium carbonate.

[0042] In some specific embodiments of the present invention, in step S3, the organic phase used for extraction includes, by volume percentage, 10%-30% of an extractant, 5%-10% of a modifier and the remainder of solvent oil.

[0043] In some embodiments, typically but not limiting, for example, the volume percentage of the extractant can be any point value among 10%, 15%, 20%, 25%, 30%, or a range value consisting of any two point values; the volume percentage of the modifier can be any point value among 5%, 6%, 7%, 8%, 9%, 10%, or a range value consisting of any two point values.

[0044] In some specific embodiments of the present invention, the extractant used includes at least one of P204, P507, C272, and P350;

[0045] And / or, the modifier used includes TBP and / or isooctyl alcohol.

[0046] In some specific embodiments of the present invention, in step S3, the extraction ratio O / A is 1:2-4, for example, it can be any point value among 1:2, 1:2.5, 1:3, 1:3.5, 1:4 or a range value consisting of any two point values.

[0047] In some specific embodiments of the present invention, in step S4, the stripping agent used includes sulfuric acid and / or hydrochloric acid.

[0048] In some specific embodiments of the present invention, the concentration of sulfuric acid used for stripping is 2-4M, for example, it can be any point value among 2M, 2.5M, 3M, 3.5M, 4M or a range value consisting of any two point values.

[0049] In some specific embodiments of the present invention, the concentration of hydrochloric acid used for stripping is 2-4N, for example, it can be any point value among 2N, 2.5N, 3N, 3.5N, 4N or a range value consisting of any two point values.

[0050] In some specific embodiments of the present invention, in step S4, the organic phase obtained after stripping of the vanadium-rich stripping solution can be returned to the front stage for extraction again, thereby achieving the reuse of the organic phase.

[0051] In some specific embodiments of the present invention, in step S4, the ratio O / A of stripping is 2-6:1, for example, it can be any point value among 2:1, 3:1, 4:1, 5:1, 6:1 or a range value consisting of any two point values.

[0052] In some specific embodiments of the present invention, in step S5, the oxidant used includes at least one of sodium chlorate, sodium hypochlorite and sodium chlorite.

[0053] In some specific embodiments of the present invention, in step S5, oxidative hydrolysis precipitation of vanadium is carried out under water bath heating conditions to generate sodium polyvanadate precipitate, and the product and vanadium-containing mother liquor wastewater are obtained after solid-liquid separation, and the vanadium-containing mother liquor wastewater is directly blended and circulated; wherein the water bath heating temperature is 80-100°C, for example, it can be any point value among 80°C, 85°C, 90°C, 95°C, 100°C, or a range value consisting of any two point values.

[0054] The following is a detailed description of some embodiments of the present invention in conjunction with specific examples. The raw materials used in the examples can be purchased from the market unless otherwise specified.

[0055] Example 1

[0056] The vanadium-containing mother liquor wastewater produced by oxidation and hydrolysis of vanadium precipitation in the process of extracting vanadium from titanium dioxide waste acid by the chloride process contains 1.5g / L of vanadium, and the vanadium-containing mother liquor wastewater and the vanadium-containing waste acid of titanium dioxide by the chloride process contain 3g / L of vanadium. The volume ratio is divided according to the vanadium-containing mother liquor wastewater: the chlorination process titanium dioxide waste acid = 1:10. The vanadium-containing mother liquor wastewater is mixed with the chlorination process titanium dioxide waste acid. After the mixed feed liquid is heated to 55°C, liquid alkali is added to neutralize the feed liquid to a pH value of about 1.0. After the feed liquid precipitates, it is filtered to separate the clarified feed liquid. No vanadium is lost during the neutralization process. The feed liquid contains 2.76g / L of vanadium. By volume percentage, 20% P204+5% TBP+75% kerosene is used as an organic phase, and the clarified liquid separated after neutralization is subjected to 6-stage countercurrent extraction according to a relative ratio of O / A=1:3 to obtain a vanadium-rich organic phase and a raffinate, wherein the raffinate contains 0.01 g / L vanadium and the extraction rate is 99.6%. The vanadium-rich organic phase is subjected to 8-stage countercurrent stripping with 2M sulfuric acid according to a relative ratio of O / A=6:1, and the organic phase after stripping does not contain vanadium, and the stripping rate is 100%. Sodium chlorate (0.25 times the mass of vanadium) and 32% liquid alkali (1 / 10 of the volume of the neutralized liquid) are added to the vanadium-rich stripping liquid, and the mixture is stirred under a 90° C. water bath heating condition to oxidize and hydrolyze vanadium to precipitate vanadium, and red vanadium product and vanadium-containing mother liquor wastewater are obtained after solid-liquid separation, and the product is sold, and the vanadium-containing mother liquor wastewater is directly returned to the front stage for mixing and circulation with the chlorination process titanium dioxide waste acid, and the overall vanadium recovery rate of the vanadium-containing wastewater is above 99.5%. At the same time, the wastewater circulation avoids the additional treatment of the vanadium-containing wastewater and also reduces the vanadium recovery cost.

[0057] Example 2

[0058] Example 2 is similar to Example 1, except that the mixing ratio of vanadium-containing mother liquor wastewater and chlorination titanium dioxide waste acid is different. The specific process is as follows:

[0059] The vanadium-containing mother liquor wastewater produced by oxidation and hydrolysis of vanadium precipitation in the process of extracting vanadium from titanium dioxide waste acid by the chloride process contains 1.5g / L of vanadium, and the vanadium-containing mother liquor wastewater and the vanadium-containing waste acid of titanium dioxide by the chloride process contain 3g / L of vanadium. The volume ratio is divided into vanadium-containing mother liquor wastewater: chlorination process titanium dioxide waste acid = 1:1. The vanadium-containing mother liquor wastewater is mixed with the chlorination process titanium dioxide waste acid. After the mixed feed liquid is preheated to 55°C, liquid alkali is added to neutralize the feed liquid to a pH value of about 1.0. After the feed liquid precipitates, it is filtered to separate the clarified feed liquid. No vanadium is lost during the neutralization process. The feed liquid contains 2.15g / L of vanadium. By volume percentage, 20% P204+5% TBP+75% kerosene is used as the organic phase, and the clarified liquid separated after neutralization is subjected to 6-stage countercurrent extraction according to the ratio O / A=1:3 to obtain a vanadium-rich organic phase and a raffinate, the raffinate contains 0.5 g / L vanadium, and the extraction rate is 76.7%. The vanadium-rich organic phase is subjected to 8-stage countercurrent stripping with 2M sulfuric acid according to the ratio O / A=6:1, and the organic phase after stripping does not contain vanadium, and the stripping rate is 100%. Sodium chlorate (0.25 times the mass of vanadium) and 32% liquid alkali (1 / 10 of the volume of the neutralized liquid) are added to the vanadium-rich stripping liquid, and the mixture is stirred under heating conditions of 90°C in a water bath to oxidize and hydrolyze vanadium to precipitate vanadium. After solid-liquid separation, a red vanadium product and vanadium-containing mother liquor wastewater are obtained, and the product is sold, and the vanadium-containing mother liquor wastewater is directly returned to the front stage for mixing and circulation with the waste acid of titanium dioxide by the chloride process, and the overall vanadium recovery rate of the vanadium-containing wastewater is above 76%. Due to the large mixing ratio, pentavalent vanadium cannot be completely reduced, resulting in a decrease in the vanadium recovery rate.

[0060] Example 3

[0061] The difference between Example 3 and Example 1 is that the volume ratio of vanadium-containing mother liquor wastewater to chlorination process titanium dioxide waste acid is 1:80, and the other conditions are the same as Example 1. Compared with Example 1, the vanadium recovery rate does not decrease, but the vanadium-containing mother liquor wastewater generated by oxidative hydrolysis and vanadium precipitation in the process of extracting vanadium with chlorination process titanium dioxide waste acid is 1 / 30 of the volume of titanium dioxide waste acid, and the vanadium-containing mother liquor wastewater cannot be completely consumed.

[0062] Comparative Example 1

[0063] The difference between Comparative Example 1 and Example 1 is that the vanadium-containing mother liquor wastewater obtained by oxidative hydrolysis precipitation of vanadium is not recycled and blended into the chloride process titanium dioxide waste acid. Lime milk is directly added to the vanadium-containing mother liquor wastewater to neutralize it to a pH of 10, and then the vanadium is precipitated. The wastewater is discharged and the vanadium is not recovered, resulting in a waste of vanadium resources.

[0064] Comparative Example 2

[0065] The vanadium-containing mother liquor wastewater obtained by oxidative hydrolysis precipitation of vanadium is not recycled and mixed into the waste acid of titanium dioxide produced by the chloride process. The pentavalent vanadium in the vanadium-containing mother liquor wastewater is first reduced to tetravalent vanadium using a reducing agent, sodium sulfite, and then recovered by extraction using an extractant. However, the pentavalent vanadium-containing mother liquor wastewater also contains trivalent iron, and a large amount of reducing agent is required, resulting in high cost.

[0066] Although the present invention has been illustrated and described with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents without departing from the spirit and scope of the present invention. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A vanadium-containing mother liquor wastewater recycling process, characterized in that: The following steps are involved: The vanadium-containing mother liquor wastewater produced by oxidative hydrolysis and vanadium precipitation in the process of extracting vanadium from titanium dioxide waste acid by the chloride process is directly mixed with the titanium dioxide waste acid by the chloride process for cyclic extraction and vanadium extraction.

2. The vanadium-containing mother liquor wastewater recycling process according to claim 1, characterized in that: The volume ratio of the vanadium-containing mother liquor wastewater to the chlorination process titanium dioxide waste acid is 1:1-80.

3. The vanadium-containing mother liquor wastewater recycling process according to claim 1, characterized in that: The vanadium-containing mother liquor wastewater recycling process comprises the following steps: S1. blending the vanadium-containing mother liquor wastewater into the chloride process titanium dioxide waste acid; S2. The blended liquid is neutralized to a pH of 0.5-1.5, and after precipitation of the liquid, the clarified liquid is separated; S3. Adding an organic phase to the clarified liquid for extraction to obtain a vanadium-rich organic phase; S4. stripping the vanadium-rich organic phase with a stripping agent to obtain a vanadium-rich stripping solution, and transferring vanadium from the organic phase to the aqueous phase; S5. Add an oxidant to the vanadium-rich stripping solution to carry out oxidative hydrolysis and precipitation of vanadium, and the vanadium-containing mother liquor wastewater obtained by solid-liquid separation is circulated to step S1 for blending.

4. The vanadium-containing mother liquor wastewater recycling process according to claim 3, characterized in that: In step S2, the alkali used in the neutralization liquid preparation process includes at least one of sodium hydroxide, sodium carbonate, and calcium carbonate.

5. The vanadium-containing mother liquor wastewater recycling process according to claim 3, characterized in that: In step S3, the organic phase includes, by volume percentage, 10%-30% of an extractant, 5%-10% of a modifier and the remainder of solvent oil.

6. The vanadium-containing mother liquor wastewater recycling process according to claim 5, characterized in that: The extractant includes at least one of P204, P507, C272, and P350; And / or, the modifier includes TBP and / or isooctyl alcohol.

7. The vanadium-containing mother liquor wastewater recycling process according to claim 3, characterized in that: In step S3, the extraction phase ratio O / A is 1:2-4.

8. The vanadium-containing mother liquor wastewater recycling process according to claim 3, characterized in that: In step S4, the stripping agent includes sulfuric acid and / or hydrochloric acid.

9. The vanadium-containing mother liquor wastewater recycling process according to claim 3, characterized in that: In step S4, the phase ratio O / A of the stripping is 2-6:

1.

10. The vanadium-containing mother liquor wastewater recycling process according to claim 3, characterized in that: In step S5, the oxidant includes at least one of sodium chlorate, sodium hypochlorite, sodium chlorite, and hydrogen peroxide.

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