A method for recovering tungsten and ammonia from a sulfidation residue of an ammonium tungstate feed solution

Abstract

The present application relates to the technical field of tungsten recovery, and particularly relates to a method for recovering tungsten and ammonia from a sulfidation impurity-removing residue of an ammonium tungstate feed liquid. The method comprises the following steps: (1) adding a stripping column discharge feed liquid to the sulfidation impurity-removing residue to obtain a slurry feed liquid, wherein the temperature of the stripping column discharge feed liquid is greater than 80 DEG C, the alkalinity is 4-5 g / l, and the ammonia nitrogen content is less than or equal to 10 ppm; (2) adding alkali to the slurry feed liquid at a preset temperature and maintaining the alkalinity of the solution within a first range to obtain a solid-liquid mixture; (3) filtering the solid-liquid mixture to obtain an initial filtrate and an initial filter residue, and stripping the initial filtrate to remove ammonia; (4) adding an acid liquid to the initial filter residue and maintaining the acidity of the solution within a second range to obtain a dissolved solution; and (5) using an anion resin to adsorb and desorb the dissolved solution to obtain a tungsten recovery solution. The method provided by the present application can improve the tungsten recovery rate, has a small process flow, greatly reduces the consumption of steam and caustic soda, has a small amount of residue after acid treatment, reduces secondary treatment of the residue, and significantly reduces the cost.

Description

Technical Field

[0001] This invention relates to the field of tungsten recovery technology, and in particular to a method for recovering tungsten and ammonia from the sulfidation residue of ammonium tungstate solution. Background Technology

[0002] In the tungsten smelting industry, ammonium tungstate sulfidation for impurity removal is a crucial step in tungsten purification. However, traditional methods face multiple technical challenges. First, this method involves multiple pressure filtrations and washings of the impurity-laden slag. This process significantly increases the total volume of the feed solution and generates a large amount of filtrate rich in impurities and incompletely recovered resources. These filtrates often contain high levels of residual alkali, requiring substantial amounts of neutralizing agents to adjust the pH, thus increasing the cost burden of subsequent processing stages. Furthermore, removing moisture from the filtrate requires multiple heating and evaporation processes, which are not only energy-intensive, particularly with a significant increase in steam consumption, but also exacerbate the environmental burden. Even more seriously, the highly alkaline slag after multiple pressure filtrations is classified as hazardous waste, making its safe treatment and disposal a major challenge.

[0003] On the other hand, high ammonia content in the solution becomes a significant limiting factor when using resin adsorption technology to recover polytungstate ions from the filtrate. A high ammonia environment not only reduces the resin's adsorption efficiency for tungsten, causing the adsorbed tungsten to decompose, thus affecting the resin's adsorption capacity and lifespan, but also increases the cost of subsequent desorption treatment. Simultaneously, during transportation, high-ammonia solutions easily form ammonium sulfate and other salt crystals in the pipelines. These crystals not only clog the pipelines, reducing the effective flow rate of the adsorption column, but also increase maintenance difficulty and production costs, posing a serious threat to the stability and efficiency of the entire process. Therefore, improving existing ammonium tungstate solution sulfidation for impurity removal and recovery technology to reduce energy consumption, lower costs, improve resource recovery rates, and enhance environmental friendliness has become an urgent technical problem to be solved. Summary of the Invention

[0004] To address the shortcomings of the prior art, the present invention provides a method for recovering tungsten and ammonia from the sulfidation residue of ammonium tungstate solution.

[0005] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0006] A method for recovering tungsten and ammonia from the sulfidation residue of ammonium tungstate feed liquid includes the following steps:

[0007] (1) Add stripping tower effluent to the sulfidation impurity removal slag to prepare slurry, and the temperature of the stripping tower effluent is greater than 80℃, the alkalinity is 4-5g / l, and the ammonia nitrogen content is ≤10ppm.

[0008] (2) Add alkali to the slurry at a preset temperature and maintain the alkalinity of the solution within a first range to obtain a solid-liquid mixture;

[0009] (3) The solid-liquid mixture is filtered to obtain a primary filtrate and a primary filtrate residue, and the primary filtrate is stripped to remove ammonia.

[0010] (4) Add acid to the primary filter residue and maintain the acidity of the solution within the second range to obtain a solution;

[0011] (5) The solution is adsorbed and desorbed using an anion exchange resin to obtain tungsten recovery solution.

[0012] In one embodiment, the tungsten content in the sulfidation residue is 0.3%-5%, and the ammonia content is 7%-10%.

[0013] In one embodiment, in step (1), the solid-liquid ratio after slurry preparation is greater than 1:4.

[0014] In one embodiment, in step (2), the alkali is caustic soda flakes, and the amount of alkali added is to maintain the alkalinity of the solution in the range of 10-20 g / L.

[0015] In one embodiment, in step (2), the preset temperature is 75-98°C;

[0016] Preferably, the preset temperature is 80°C and the reaction time for adding alkali is 1 hour.

[0017] In one embodiment, step (2) further includes collecting and adsorbing the free ammonia gas generated during the reaction.

[0018] In one embodiment, step (3) further includes a secondary treatment of the primary filter residue, wherein the secondary treatment is acid dissolution of the primary filter residue.

[0019] In one embodiment, in step (4), the acid solution contains at least one of hydrochloric acid, sulfuric acid, phosphoric acid, and carbonic acid.

[0020] In one embodiment, in step (4), the amount of acid added is such that the acidity of the solution is maintained in the range of 10-20 g / L.

[0021] In one embodiment, in step (3), the stripping deammoniation effluent is added to the next cycle of slurry preparation as the stripping tower effluent from step (1).

[0022] Based on the above, compared with the prior art, the method for recovering tungsten and ammonia from the sulfidation residue of ammonium tungstate feed solution provided by the present invention improves the tungsten recovery rate while significantly reducing the number of process steps; the use of stripped recovery material for slurry preparation, which has a high temperature and contains residual alkali, can reduce the consumption of steam and alkali; the amount of residue after acid addition is reduced, thereby reducing the need for secondary treatment of filter residue; and the cost is significantly reduced.

[0023] Other features and beneficial effects of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other beneficial effects of the invention can be realized and obtained by means of the structures particularly pointed out in the description, claims and drawings. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Unless otherwise specified, the positional relationships shown in the drawings in the following description are based on the direction in which the components are drawn in the figure.

[0025] Figure 1 The flowchart illustrates a method for recovering tungsten and ammonia from the sulfidation residue of ammonium tungstate feed solution, as provided in an embodiment of the present invention. Detailed Implementation

[0026] In the description of this invention, it should be noted that all terms used in this invention (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains, and should not be construed as limiting the invention; it should be further understood that the terms used in this invention should be understood to have the same meaning as those in the context of this specification and in the relevant field, and should not be understood in an idealized or overly formal sense, except as expressly defined in this invention.

[0027] This invention provides a method for recovering tungsten and ammonia from the sulfidation residue of ammonium tungstate solution, comprising the following steps:

[0028] Step (1): Add stripping tower effluent to the sulfidation residue to prepare the slurry, and the temperature of the stripping tower effluent is greater than 80℃, the alkalinity is 4-5g / l, and the ammonia nitrogen content is ≤10ppm.

[0029] The sulfidation residue contains 0.3%-5% tungsten and 7%-10% ammonia.

[0030] This invention combines deep ammonia removal with a subsequent stripping tower, directly using the stripping tower effluent for slurry preparation. On one hand, the high temperature of the stripping tower effluent significantly reduces the consumption of subsequent steam or heating; on the other hand, the inherent alkalinity of the stripping tower effluent reduces the amount of caustic soda flakes needed in subsequent steps. Specifically, the stripping tower effluent used in this invention must meet the following requirements: temperature greater than 80°C, preferably 98°C, and alkalinity within the range of 4-5 g / L.

[0031] In a preferred embodiment, the solid-liquid ratio after slurry preparation is above 1:4, which is beneficial for fully stirring the sulfidation slag and preventing agglomeration, thus facilitating better subsequent ammonia removal and tungsten removal.

[0032] Step (2): Add alkali to the slurry solution at a preset temperature and maintain the alkalinity of the solution within a first range to obtain a solid-liquid mixture;

[0033] By adding alkali, preferably caustic soda flakes, to the slurry, ammonia is released from the sulfidation residue and enters the solution under a preset temperature and alkaline environment, especially a strongly alkaline environment, or from ammonium ions in the solution. It will be converted into free ammonia (NH3), and the reaction between the sulfide residue and alkali will also generate alkali salts (such as calcium hydroxide, magnesium hydroxide, etc.). Since the tungsten-containing substances that can react with alkali have already reacted completely during the alkali treatment process, the tungsten-containing substances in this step react to become sodium tungstate solution. As for the generated free ammonia gas, dilute sulfuric acid is used for absorption and reaction, thereby removing ammonia from the slurry. The above process includes the following reaction formulas:

[0034] XPO4NH4+NaOH→XOH↓+XNaPO4↓+NH3·H2O;

[0035]

[0036] 2NH3 + H2SO4 = (NH4)2SO4;

[0037] H + +OH - =H2O;

[0038] Wherein, X refers to a metal cation;

[0039] The preset temperature is 75-98℃, for example, it can be 80℃, preferably above 80℃, to improve the deammoniation efficiency and reduce the solid ammonia content in the residue. The reaction time for adding alkali is adjusted according to the amount of residual ammonia. For example, if the preset temperature is 80℃ and the alkali addition time is 1 hour, it can effectively ensure that the deammoniation and tungsten dissolution reactions are fully carried out, and achieve the expected conversion rate and extraction effect.

[0040] Furthermore, the amount of alkali added is sufficient to maintain the alkalinity of the solution within the range of 10-20 g / L. This ensures normal deammoniation while controlling the consumption of caustic soda flakes, thereby reducing processing costs.

[0041] Step (3): Filter the solid-liquid mixture to obtain a primary filtrate and a primary filtrate residue, and strip the primary filtrate to remove ammonia;

[0042] The primary filter residue mainly contains magnesium ammonium phosphate, calcium hydroxide, magnesium hydroxide, calcium sulfate, magnesium sulfate, calcium tungstate, etc.; the primary filtrate mainly contains sodium tungstate, ammonia, etc.

[0043] Step (3) further includes a secondary treatment of the primary filter residue, wherein the secondary treatment is to dissolve the primary filter residue with acid to further dissolve the tungsten in the primary filter residue, so as to facilitate the subsequent enrichment and recovery of tungsten using resin.

[0044] During the stripping and deammoniation process, the deammoniation temperature is controlled within the range of 99-105℃, and the alkalinity of the liquid environment is controlled within the range of 5-10g / l.

[0045] In step (3), the stripping deammoniation effluent can be used as the stripping tower effluent from step (1) and directly added to the next cycle of slurry preparation, thereby realizing the recycling of materials and effectively reducing costs.

[0046] Step (4): Add acid to the primary filter residue and maintain the acidity of the solution within the second range to obtain a solution;

[0047] In step (4), by adding acid, especially sulfuric acid, sulfate ions and calcium ions form a precipitate, which is intercepted by a secondary filter / pressure filter, reducing the formation of slag in the subsequent resin adsorption process; while the tungsten still contained in the slag exists in the form of polytungstate, which is convenient for the resin adsorbent to be enriched, and other impurities are separated.

[0048] In step (4), the acid solution contains at least one of hydrochloric acid, sulfuric acid, phosphoric acid, and carbonic acid, with sulfuric acid being preferred.

[0049] In step (4), the amount of acid added is such that the acidity of the solution is maintained in the range of 10-20 g / L. This control of acidity is beneficial to the subsequent adsorption of tungsten by the anion exchange resin.

[0050] (5) The solution is adsorbed and desorbed using an anion exchange resin to obtain tungsten recovery solution.

[0051] The anion exchange resin is preferably a macroporous anion exchange resin with a high affinity for polytungstate, such as anion exchange resin 301.

[0052] It should be noted that the inventors discovered that when using resin to adsorb tungsten, if the ammonia content in the adsorption solution is too high, the adsorbed tungsten will be decomposed, affecting the resin's adsorption capacity and thus significantly increasing the number of analytical steps required, leading to high analytical costs. Therefore, thorough deammoniation is performed first to significantly reduce the ammonia content in the solution, even to near zero, thereby not affecting the resin's adsorption capacity for tungsten and reducing analytical costs. Furthermore, if the ammonia content in the solution is too high, ammonium sulfate crystals are easily formed in the pipeline after adding sulfuric acid, affecting the adsorption column flow rate. Therefore, prioritizing ammonia removal reduces the ammonia content in the solution, preventing crystallization in the pipeline. In addition, the inventors found that the prior acid dissolution method in the existing technology results in a high ammonia content in the solution, forming suspended fine sludge with a long settling time. In contrast, the present invention uses prior ammonia removal, resulting in a low ammonia content in the solution, a clear feed liquid, and direct adsorption without settling, significantly shortening the processing cycle.

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0054] Examples 1-12

[0055] Select ammonium tungstate solution from the same batch for sulfidation to remove impurities and slag. The composition is shown in the table below. Divide the solution into 12 portions of equal weight. Add stripping tower effluent (effluent temperature ≥90℃, alkalinity: 4-5g / l) under the same conditions to each portion for slurry preparation and boiling. After reacting for the same time, 12 portions of slurry preparation solution are obtained.

[0056] Table 1

[0057] Magnesium ammonium phosphate 50 calcium hydroxide 15 Magnesium hydroxide 15 Magnesium sulfate 8 Calcium sulfate 5 Calcium tungstate 3 other 4

[0058] Each batch of slurry was subjected to deammoniation and tungsten dissolution at different temperatures and alkalinities. The specific reaction data are shown in Table 2 below.

[0059] Table 2

[0060]

[0061] As shown in Table 1, the ammonia content in the solution decreases significantly with increasing temperature; the tungsten dissolution rate of the slag also increases with increasing temperature; however, considering that the slag viscosity is low when the alkalinity is 10-20 g / L, which is conducive to filtration, the pressure filtration time can be effectively reduced, thereby improving efficiency.

[0062] Examples 13-24

[0063] Using the same batch of ammonium tungstate solution as in Examples 1-12, sulfidation was performed to remove impurities and slag. The solution was divided into 12 portions of equal weight. Each portion was added to the stripping tower effluent solution under the same conditions (effluent temperature ≥90℃, alkalinity: 4-5g / l) for slurry preparation and boiling. After reacting for the same time, 12 portions of slurry solution were obtained. Then, the 12 portions of slurry solution were subjected to deammoniation and tungsten removal at a temperature of 80℃, a solution alkalinity controlled at 20g / l, and a reaction time of 60min to obtain a solid-liquid mixture.

[0064] The solid-liquid mixture was filtered by a filter press to obtain primary filtrate and primary filtrate residue. The primary filtrate was stripped to remove ammonia. Each portion of the primary filtrate was then subjected to residue decomposition at different temperatures and acidities. The specific reaction and tungsten dissolution rate data are shown in Table 3 below.

[0065] Table 3. Tungsten dissolution rate of the residue after alkali dissolution followed by acid dissolution.

[0066]

[0067] As can be seen from Table 2, acid dissolution results in less slag in the solution, reducing the need for processing tungsten-containing slag; temperature has little effect on the slag content (dry slag) after dissolution; the adsorption of polytungstic acid by 301 resin needs to be carried out under acidic conditions, and the acidity of dissolution should be controlled at 10-20 g / L.

[0068] Furthermore, those skilled in the art should understand that although many problems exist in the prior art, each embodiment or technical solution of the present invention can be improved in only one or a few aspects, without necessarily solving all the technical problems listed in the prior art or the background art simultaneously. Those skilled in the art should understand that any content not mentioned in a claim should not be construed as a limitation on that claim.

[0069] Although this document frequently uses terms such as sulfidation impurity removal slag, slurry conditioning, solid-liquid mixture, primary filtrate, primary filtrate residue, stripping deammoniation, alkalinity, acidity, solution, and tungsten recovery solution, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would contradict the spirit of the invention. The terms "first," "second," etc. (if present) in the specification, claims, and accompanying drawings of the embodiments of the invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for recovering tungsten and ammonia from the sulfidation residue of ammonium tungstate feed solution. Its features are, Includes the following steps: (1) Add stripping tower effluent to the sulfidation residue to prepare slurry, and the solid-liquid ratio after slurry preparation is above 1:

4. The temperature of the stripping tower effluent is above 80℃, the alkalinity is 4-5g / l, and the ammonia nitrogen content is ≤10ppm. (2) Add alkali to the slurry solution at a preset temperature and maintain the alkalinity of the solution within a first range to obtain a solid-liquid mixture. The preset temperature is 75-98℃. Step (2) also includes collecting and adsorbing the free ammonia gas generated during the reaction. (3) The solid-liquid mixture is filtered to obtain a primary filtrate and a primary filtrate residue. The primary filtrate is stripped to remove ammonia. The stripped ammonia residue is used as the stripping tower residue from step (1) and added to the next cycle of slurry preparation. (4) Add acid to the primary filter residue and maintain the acidity of the solution within the second range to obtain a solution; the amount of acid added is to maintain the acidity of the solution within the range of 10-20 g / L; (5) The solution is adsorbed and desorbed using an anion exchange resin to obtain tungsten recovery solution.

2. The method according to claim 1, characterized in that, The sulfidation residue contains 0.3%-5% tungsten and 7%-10% ammonia.

3. The method according to claim 1, characterized in that, In step (2), the alkali is caustic soda flakes, and the amount of alkali added is to maintain the alkalinity of the solution in the range of 10-20 g / L.

4. The method according to claim 1, characterized in that, In step (4), the acid solution contains at least one of hydrochloric acid and sulfuric acid.

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