A method for processing scheelite ore

Abstract

This invention relates to the field of scheelite processing technology, and particularly to a method for processing scheelite ore, comprising the following steps: first, slurry conditioning; pH adjustment, the method for controlling the pH value of the reaction solution includes: after controlling the reaction solution to a first pH value, lowering the pH value to a second pH value every first time period, and finally controlling the residual acid concentration of the reaction solution to be controlled at 8-11 g / L and maintained for a second time period; first filtration; second slurry conditioning; leaching; second filtration. Using the scheelite ore processing method provided by this invention, after treating the scheelite ore with a first reagent under certain conditions, followed by leaching treatment, effectively reduces the tungsten content in the slag and reduces tungsten loss. This method has the advantages of a short process, less reagent addition, less slag and solution formation, and significantly reduced tungsten loss.

Description

Technical Field

[0001] This invention relates to the field of scheelite processing technology, and in particular to a method for processing scheelite ore. Background Technology

[0002] In the field of metal mineral resource extraction and processing, scheelite, as an important tungsten-rich mineral resource, has always been a research hotspot due to its efficient and low-loss extraction technology. The main component of scheelite is calcium tungstate (CaWO4), which is usually converted into soluble tungstate through chemical methods, thereby extracting pure tungsten or tungsten compounds.

[0003] Traditional acid leaching techniques for scheelite ore primarily rely on the direct leaching reaction between the ore and a mixed sulfuric-phosphoric acid. This method is based on the principle of chemical reaction, utilizing the strong corrosiveness of the acid to decompose calcium tungstate in the scheelite ore into soluble tungstates and corresponding calcium salts. However, while this method achieves tungsten extraction to some extent, it faces numerous challenges in practical applications.

[0004] First and foremost, the most significant problem lies in the high tungsten content in the leaching residue. This is primarily because during the leaching process, some calcium tungstate fails to decompose completely, or the resulting tungstates undergo redeposition or encapsulation under specific conditions. Consequently, these tungsten elements cannot effectively enter the solution and remain in the leaching residue. This issue directly leads to increased tungsten loss, thus affecting the overall recovery rate.

[0005] Secondly, high tungsten loss leads to decreased economic benefits. In the extraction of metal mineral resources, the recovery rate directly affects production costs and the market competitiveness of the final product. Tungsten, as a strategic metal, has a high price and wide applications; therefore, improving the tungsten recovery rate is of great significance for improving the economic benefits of enterprises. However, due to the problem of high tungsten content in the leaching residue during traditional acid processing of scheelite ore, a large amount of valuable tungsten resources are wasted, severely restricting the improvement of enterprises' economic benefits.

[0006] Furthermore, high tungsten loss also has certain negative environmental impacts. During the leaching process, incompletely decomposed calcium tungstate and tungsten-containing leaching residue, if not properly handled, may cause environmental pollution. At the same time, the increased raw material input and processing costs incurred to compensate for tungsten loss indirectly increase the company's carbon emissions and energy consumption, hindering its sustainable development. Summary of the Invention

[0007] To address the high tungsten loss caused by the sulfur-phosphorus mixed acid process in the prior art, this invention provides a method for processing scheelite ore.

[0008] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0009] A method for processing scheelite ore, the method comprising the following steps:

[0010] (1) First slurry preparation: Mix scheelite ore with hot water to obtain material A;

[0011] (2) pH adjustment: Add the first reagent to the material A and react and control the pH value of the reaction solution during the reaction process to obtain material B. The method of controlling the pH value of the reaction solution includes: after controlling the reaction solution to the first pH value, lowering the pH value to the second pH value every first time period, and finally controlling the residual acid concentration of the reaction solution to 8-11 g / l and maintaining it for the second time period.

[0012] (3) First filtration: The material B is filtered to separate slag C and tungsten-containing liquid, and the slag C is washed;

[0013] (4) Second slurry preparation: The washed residue C is mixed with hot water to obtain material D;

[0014] (5) Leaching: Add a second reagent to the material D to react, control the phosphorus concentration and acidity of the reaction solution, and then heat and leach to obtain material E;

[0015] (6) Second filtration: The material E is filtered to obtain tungsten-enriched liquid and filter residue.

[0016] The processing method provided by this invention involves adding a first reagent to the slurry after it has been pre-treated with hot water and controlling the pH and acidity of the reaction solution during the reaction process. This allows the first reagent to react with some of the metal oxides (XO) in the ore. n The reaction occurs (its reaction formula is: XO + H₂) + →XYO m +H2O) and dissolve other substances soluble in this acidity, thereby reducing tungsten loss in the subsequent sulfur-phosphorus mixed acid leaching step.

[0017] This invention first controls the pH of the reaction system to a first pH value. At this first pH value, on the one hand, the first reagent can react with some substances in the ore. On the other hand, by controlling the second time period, it avoids the simultaneous occurrence of excessively high temperature and excessively low pH value in the reaction system, thereby causing tungsten to dissolve in the scheelite. The method of gradually reducing the second pH value step by step until the residual acid concentration is controlled at 8-11 g / L can also avoid the occurrence of local excessive acidity, so that tungsten will not dissolve. Moreover, since hot water is used for slurry preparation in step (1), the reaction system still has a certain temperature. In the initial reaction process of pH adjustment in step (2), although the temperature of the first reagent added is relatively low, which will cause the temperature of the reaction system to decrease to a certain extent, the temperature of the initial reaction system continues the temperature of step (1). Therefore, it can still maintain a temperature higher than the room temperature without heating. This allows the reaction between the first reagent and some substances in the ore to be accelerated at a higher temperature in the early stage when the pH value drops. After the temperature of the reaction system drops further, more precise pH control is carried out. On the one hand, other substances in the ore are removed more deeply, and on the other hand, the situation of excessive acidity in some areas is avoided.

[0018] In one embodiment, in step (1), the temperature of the hot water is 50 to 80°C. The specific temperature of the hot water can be 50, 55, 60, 65, 70, 75, 80°C, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0019] In the embodiments of the present invention, hot water is used for slurry preparation. On the one hand, it is to allow the scheelite ore to mix with water more quickly and better. On the other hand, it can increase the reaction rate in step (2). More importantly, it is beneficial to control the pH value of the reaction in step (2).

[0020] Preferably, the solid content of material A is 40%-50%; more preferably, the solid content of material A is 50%.

[0021] In one embodiment, in step (2), the residual acid concentration in the material B is controlled to be 8-11 g / l. The acidity can be 11, 10.5, 10, 9.5, 9, 8.5, 8, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, or any point value between any two of the above values.

[0022] Preferably, in step (2), the residual acidity in material B is controlled to be 9-11 g / l.

[0023] The inventors discovered that in the processing method of the present invention, the concentration of residual acid in the reaction solution in step (2) is not necessarily better the higher it is. It needs to be controlled within a certain concentration range so that the impurity elements can be continuously and stably dissolved in the liquid environment under acidic conditions. If the concentration of residual acid is too high, it will further increase the probability of the calcium tungstate contained in scheelite being decomposed. This can make the tungsten content in the tungsten-containing liquid of the product of this step at a low level.

[0024] Preferably, in step (2), the first reagent is sulfuric acid.

[0025] In one embodiment, in step (2), the first pH value is 1 to 3, and the second pH value is 0.2 to 0.3.

[0026] In the method for controlling the pH value of the reaction in this invention, after maintaining the first pH value for the first time period, the pH value is reduced to the second pH value every second time period, and the residual acid concentration of the reaction solution is finally controlled at 8-11 g / l and the reaction continues for the second time period. The first pH value is 1-3 because, on the one hand, the purpose of step (2) is to remove impurities rather than decompose the ore. If the pH value is too low, the probability of decomposition reaction of scheelite ore will easily increase. If the pH value is too high, it will be difficult to achieve the purpose of removing impurities. Therefore, in order to avoid adding too much acid per unit time, it is necessary to first control the pH value to be relatively stable at the first pH value, and then further adjust the pH. Finally, after controlling the residual acid concentration of the reaction solution to be 8-11 g / l and keeping it unchanged, the addition of the first test solution is stopped and the reaction continues for the second time period. The purpose of continuing the reaction for the second time period is to ensure the completeness of the reaction. The second time period is preferably 1 hour.

[0027] In one embodiment, in step (3), the washing liquid used for washing is hot water;

[0028] Preferably, the temperature of the hot water is 40 to 90°C. Specifically, the temperature of the hot water can be 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90°C, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0029] In one embodiment, in step (4), the temperature of the hot water is 50 to 80°C. Specifically, the temperature of the hot water can be 50, 55, 60, 65, 70, 75, 80°C, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0030] In one embodiment, in step (5), the phosphorus concentration is controlled to be 20-25 g / L;

[0031] Preferably, in step (5), the phosphorus concentration is controlled to be 25 g / L;

[0032] Preferably, in step (5), the second reagent is a phosphoric acid-sulfuric acid mixture.

[0033] In one embodiment, in step (5), the acidity is controlled to be 340-360 g / l;

[0034] Preferably, in step (5), the acidity is controlled to be 350 g / L;

[0035] Preferably, in step (5), the second reagent is a phosphoric acid-sulfuric acid mixture.

[0036] In one embodiment, in step (5), the heating temperature is 90-105°C, and the heating time is 0.5-3 hours;

[0037] Preferably, in step (5), the heating temperature is 90°C and the heating time is 1 to 2 hours.

[0038] In one embodiment, the processing method further includes:

[0039] The tungsten-containing liquid in step (3) and the tungsten-containing enrichment liquid in step (6) are mixed for tungsten recovery.

[0040] Based on the above, compared with the prior art, the scheelite ore processing method provided by the present invention has at least one of the following beneficial technical effects:

[0041] (1) The processing method provided by the present invention adopts the method of pre-treating scheelite with a first reagent under certain conditions, and then leaching with a mixed sulfuric and phosphoric acid, which can effectively reduce the tungsten content in the slag and reduce tungsten loss.

[0042] (2) The processing method provided by the present invention has a short process, a small amount of first reagent added, and less slag and solution formed, which can significantly reduce tungsten loss.

[0043] 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

[0044] 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.

[0045] Figure 1 This is a schematic flowchart of a scheelite processing method provided in an embodiment of the present invention. Detailed Implementation

[0046] 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.

[0047] The terms "first," "second," etc. (if present) in the specification, claims, and drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0048] Examples 1-7

[0049] This invention provides a method for processing scheelite ore, the method comprising the following steps:

[0050] (1) First slurry preparation: Mix scheelite ore with hot water at a mass ratio of 1:1, wherein the temperature of the hot water is 50°C, to obtain material A;

[0051] (2) pH adjustment: Add 50 g / L of dilute sulfuric acid solution to the material A and react, and control the pH value and acidity of the reaction solution during the reaction process to obtain material B. The method of controlling the pH value of the reaction solution includes: maintaining the initial pH value of the reaction solution at 3 for 2 hours, then reducing the pH value by 0.2 every 10 minutes, and finally controlling the residual acid concentration of the reaction solution at 0-70 g / L and continuing the reaction for 1 hour. The residual acid concentration of the reaction solution is controlled as shown in Table 1.

[0052] (3) First filtration: The material B is filtered to separate slag C and tungsten-containing liquid. The slag C is washed with hot water at a temperature of 60°C.

[0053] (4) Second slurry preparation: The washed residue C is mixed with hot water at a temperature of 100°C to obtain material D;

[0054] (5) Leaching: A second reagent is added to the material D for reaction. The second reagent is a mixed phosphoric acid and sulfuric acid. The concentration of 75% phosphoric acid is 25 g / L and the concentration of 98% sulfuric acid is 350 g / L. The phosphorus concentration and acidity of the reaction solution are controlled to be 25 g / L and 350 g / L, respectively. Then, the material is leached by heating at 100°C for 1 hour to obtain material E.

[0055] (6) Second filtration: The material E is filtered to obtain tungsten-enriched liquid and filter residue.

[0056] The tungsten content of the tungsten-containing liquid in step (3) and the tungsten-containing enrichment solution in step (6) was determined.

[0057] Table 1

[0058]

[0059]

[0060] Table 1 shows that as the residual acid concentration of material B increases, the tungsten content of the tungsten-containing solution increases, and the tungsten content of the filter residue after leaching also gradually increases. The best treatment effect for scheelite is achieved when the residual acid concentration of material B is controlled between 8 g / L and 11 g / L, preferably between 9 g / L and 11 g / L, resulting in a significant reduction in the tungsten content of the filter residue. Excessively high residual acid concentrations can easily lead to an increased probability of calcium tungstate decomposition, forming other substances that cannot be decomposed in subsequent leaching processes, thus leading to an increase in the tungsten content of the filter residue. Conversely, excessively low residual acid concentrations make it difficult to ensure that other impurities in material B are stably stabilized by the first reagent reaction.

[0061] Comparative Examples 1-6

[0062] The differences between these comparative examples and Examples 1-16 are: the first reagent added is laundry detergent, the pH value of the reaction solution is controlled at 7, and the remaining steps and parameters are the same; some parameters and test data of comparative examples 1-6 are detailed in the table below:

[0063] Table 2

[0064]

[0065]

[0066] Table 2 shows that when laundry detergent is used as the first reagent, the pH value of the reaction solution controlled in step (2) is 7, and the subsequent leaching steps and parameters are consistent. Since the main component of laundry detergent is surfactant, although surfactant has the ability to remove dirt, it is difficult to remove impurities on the surface of the ore. Therefore, the tungsten content of the tungsten-containing liquid is extremely low, and it is difficult to effectively reduce tungsten loss in the subsequent leaching reaction.

[0067] Comparative Examples 7-12

[0068] The differences between these comparative examples and Examples 1-7 are as follows: the first reagent added is 50 g / L caustic soda flakes; the pH value of the reaction solution controlled in step (2) is controlled between 7 and 12; and the subsequent leaching steps and parameters are the same. For some parameters and test data of comparative examples 7-12, please refer to the table below:

[0069] Table 3

[0070]

[0071] Table 3 shows that when caustic soda is used as the first reagent to react with scheelite and the pH values ​​are controlled at 7, 8, 9, 10, 11 and 12 respectively, as the pH value increases, scheelite reacts with caustic soda in the following way: CaWO4(s) + 2NaOH(aq) = Na2WO4(aq) + Ca(OH)2(s). These reaction products are difficult to decompose in subsequent reactions, resulting in a significant increase in the tungsten content in the filter residue.

[0072] 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 processing scheelite ore, characterized in that, The processing method includes the following steps: (1) First slurry preparation: Mix scheelite ore with hot water to obtain material A; (2) pH adjustment: Add the first reagent to the material A and react and control the pH value of the reaction solution during the reaction process to obtain material B. The method of controlling the pH value of the reaction solution includes: after controlling the reaction solution to the first pH value, lowering the pH value to the second pH value every first time period, and finally controlling the residual acid concentration of the reaction solution to be controlled at 8-11 g / l and maintaining it for the second time period; in step (2), the first reagent is sulfuric acid; the first pH value is 1~3, and the second pH value is 0.2~0.3; (3) First filtration: The material B is filtered to separate slag C and tungsten-containing liquid, and the slag C is washed; (4) Second slurry preparation: The washed residue C is mixed with hot water to obtain material D; (5) Leaching: Add the second reagent to the material D to react, control the phosphorus concentration and acidity of the reaction solution, and then heat and leach to obtain material E; in step (5), control the phosphorus concentration to be 20-25 g / l, the second reagent is a phosphorus-sulfur mixed acid, and control the acidity to be 340-360 g / l; (6) Second filtration: The material E is filtered to obtain tungsten-enriched liquid and filter residue.

2. The method for processing scheelite ore according to claim 1, characterized in that, In step (1), the temperature of the hot water is 50~80℃.

3. The method for processing scheelite ore according to claim 1, characterized in that, The solid content of material A is 40%-50%.

4. The method for processing scheelite ore according to claim 1, characterized in that, In step (2), the concentration of residual acid in material B is controlled to be 9-11 g / l.

5. The method for processing scheelite ore according to claim 1, characterized in that, In step (3), the washing liquid used for washing is hot water.

6. The method for processing scheelite ore according to claim 5, characterized in that, In step (3), the temperature of the hot water is 40~90℃.

7. The method for processing scheelite ore according to claim 1, characterized in that, In step (4), the temperature of the hot water is 50~80℃.

8. The method for processing scheelite ore according to claim 1, characterized in that, In step (5), the heating temperature is 90-105℃ and the heating time is 0.5-3h.

9. The method for processing scheelite ore according to claim 1, characterized in that, The processing method further includes: The tungsten-containing liquid in step (3) and the tungsten-containing enrichment liquid in step (6) are mixed for tungsten recovery.

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