Scheelite treatment method

Abstract

The invention relates to the technical field of scheelite treatment, in particular to a scheelite treatment method which comprises the following steps: first slurry mixing; the method for adjusting the pH value and controlling the pH value of the reaction solution comprises the following steps: after controlling the pH value of the reaction solution to a first pH value, reducing the pH value to a second pH value every a first time period, and finally controlling the residual acid concentration of the reaction solution to be 8-11g / l and maintaining for a second time period; first filtration; second size mixing; performing leaching; and second filtering. According to the scheelite treatment method provided by the invention, after the scheelite is treated by the first reagent under a certain condition, the scheelite is subjected to leaching treatment, so that the tungsten content in slag is effectively reduced, and the tungsten loss is reduced. The method has the advantages of short flow, less reagent addition, less formed slag and solution, and great reduction of tungsten loss.

Description

Technical Field

[0001] The invention relates to the technical field of scheelite processing, and in particular to a scheelite ore processing method. Background Art

[0002] In the field of extraction and processing of metal mineral resources, scheelite ore, as an important mineral resource rich in tungsten, has always been a hot research topic in the industry for its efficient and low-loss extraction technology. The main component of scheelite ore is calcium tungstate (CaWO4), which is usually converted into soluble tungstate by chemical methods to extract pure tungsten or tungsten compounds.

[0003] The traditional acid treatment technology of scheelite ore mainly relies on the direct leaching reaction of scheelite ore with sulfuric and phosphoric acid mixture. This method is based on the principle of chemical reaction and uses the strong corrosiveness of acid to decompose calcium tungstate in scheelite ore into soluble tungstate and corresponding calcium salt. However, although this method has achieved the extraction of tungsten to a certain extent, it faces many challenges in practical application.

[0004] First, the most significant problem is the high tungsten content in the leaching residue. This is mainly because during the leaching process, part of the calcium tungstate fails to decompose completely, or the tungstate generated after decomposition reprecipitates or wraps under certain conditions, resulting in the inability of these tungsten elements to effectively enter the solution, but remain in the leaching residue. The existence of this problem directly leads to an increase in tungsten loss, which in turn affects the overall recovery rate.

[0005] Secondly, high tungsten loss leads to a decline in economic benefits. In the process of extracting metal mineral resources, the recovery rate is directly related to the production cost and the market competitiveness of the final product. As a strategic metal, tungsten is relatively expensive and widely used, so improving the recovery rate of tungsten is of great significance to improving the economic benefits of enterprises. However, due to the high tungsten content in the leached slag during the traditional acid treatment of scheelite ore, a large amount of valuable tungsten resources are wasted, which seriously restricts the improvement of the economic benefits of enterprises.

[0006] In addition, high tungsten loss also has a certain negative impact on the environment. In the leaching process, incompletely decomposed calcium tungstate and tungsten-containing leaching residues may pollute the environment if not properly handled. At the same time, the increased raw material input and processing costs to compensate for tungsten loss will also indirectly increase the company's carbon emissions and energy consumption, which is not conducive to the sustainable development of the company. Summary of the invention

[0007] In order to solve the high tungsten loss caused by the sulfur-phosphorus mixed acid process in the above-mentioned prior art, the present invention provides a method for treating scheelite ore;

[0008] In order to solve the above technical problems, the technical solutions provided by the present invention are as follows:

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

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

[0011] (2) pH adjustment: adding a first reagent to the material A to react and controlling the pH value of the reaction solution during the reaction to obtain material B, wherein the method for controlling the pH value of the reaction solution comprises: after controlling the reaction solution to a first pH value, reducing the pH value to a 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 a second time period;

[0012] (3) First filtration: filtering the material B to separate the slag C and the tungsten-containing liquid, and washing the slag C;

[0013] (4) Second slurry preparation: mixing the washed slag C with hot water to obtain material D;

[0014] (5) Leaching: adding a second reagent to the material D to react, controlling the phosphorus concentration and acidity of the reaction solution, and then heating and leaching to obtain material E;

[0015] (6) Second filtration: filtering the material E to obtain a tungsten-containing enriched liquid and a filter residue.

[0016] The treatment method provided by the present invention is to add a first reagent to the slurry after hot water slurrying in advance and control the pH value and acidity of the reaction solution during the reaction so that the first reagent reacts with part of the metal oxides (XO n ) reacts (the reaction formula is: XO+H + →XYO m +H2O) and dissolve other substances soluble in this acidity, thereby reducing tungsten loss in the subsequent sulfur-phosphorus mixed acid process leaching step.

[0017] The present invention controls the pH of the reaction system to a first pH value. At the first pH value, on the one hand, the first reagent can react with some substances in the ore. On the other hand, the second time period is controlled to avoid the temperature of the reaction system being too high and the pH value being too low at the same time, thereby dissolving the tungsten in the scheelite. The control method of gradually reducing the second pH value 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 be dissolved. In addition, since hot water is used for slurry adjustment in step (1), the reaction system still has a certain temperature. In the initial reaction process of adjusting the pH in step (2), although the temperature of the added first reagent is relatively low, the temperature of the reaction system will be reduced to a certain extent. However, since the temperature of the initial reaction system continues the temperature of step (1), it can still maintain a temperature higher than room temperature without heating, so that when the pH value drops in the early stage, the reaction between the first reagent and some substances in the ore is accelerated at a higher temperature. After the temperature of the reaction system drops further, more precise pH control is performed, which can remove other substances in the ore at a deeper level on the one hand, and avoid the occurrence of local excessive acidity on the other hand.

[0018] In one embodiment, in step (1), the temperature of the hot water is 50-80° C. 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 values ​​not listed in the range are also applicable.

[0019] In the embodiment of the present invention, hot water is used for slurry preparation, on the one hand, to allow the scheelite ore and water to mix faster and better, and on the other hand, to 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, and the acidity can be specifically 11, 10.5, 10, 9.5, 9, 8.5, 8, etc., but is not limited to the listed values, and other values ​​not listed in the range are also applicable, or the point value between any two of the above values;

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

[0023] The inventors have found that in the treatment method of the present invention, the residual acid concentration of the reaction solution in step (2) is not the higher the better, but 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 an acidic environment. If the residual acid concentration is too high, it will further increase the probability of calcium tungstate contained in the scheelite being decomposed, thereby making the tungsten content in the product tungsten-containing liquid of this step at a lower level.

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

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

[0026] In the method for controlling the pH value of the reaction of the present invention, the first pH value is maintained for a first time period, and then the pH value is reduced to a second pH value every second time period, and finally the residual acid concentration of the reaction solution is controlled to be 8-11 g / l and the reaction is carried out for a 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 the decomposition reaction of the scheelite ore is easily increased, and if the pH value is too high, it is 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 to be relatively stable at the first pH value, and then further adjust the pH. Finally, after the residual acid concentration of the reaction solution is controlled to be 8-11 g / l and remains unchanged, the addition of the first test solution is stopped and the reaction is continued for a second time period. The purpose of further maintaining 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 in the washing is hot water;

[0028] Preferably, the temperature of the hot water is 40-90°C. 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, and other unlisted values ​​within the range are also applicable.

[0029] In one embodiment, in step (4), the temperature of the hot water is 50-80°C. The temperature of the hot water can specifically be 50, 55, 60, 65, 70, 75, 80°C, etc., but is not limited to the listed values. Other values ​​not listed within the 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 phosphorus-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 phosphorus-sulfuric acid mixture.

[0036] In one embodiment, in step (5), the heating temperature is 90-105° C., and the heating time is 0.5 to 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 feed solution in step (3) and the tungsten-containing enriched solution in step (6) are mixed to recover tungsten.

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

[0041] (1) The treatment method provided by the present invention uses a first reagent to treat the scheelite ore under certain conditions before leaching it with sulfur-phosphorus mixed acid, which can effectively reduce the tungsten content in the slag and reduce the tungsten loss;

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

[0043] Other features and beneficial effects of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other beneficial effects of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 A schematic flow chart of a method for processing scheelite ore provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments; the technical features designed in different implementation modes of the present invention described below can be combined with each other as long as they do not conflict with each other; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

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

[0048] Examples 1-7

[0049] The embodiment of the present invention provides a method for processing scheelite ore, the method comprising the following steps:

[0050] (1) First slurry preparation: Scheelite ore and hot water are mixed in a mass ratio of 1:1, wherein the temperature of the hot water is 50° C., to obtain material A;

[0051] (2) pH adjustment: adding 50 g / l of dilute sulfuric acid solution to the material A for reaction and controlling the pH value and acidity of the reaction solution during the reaction to obtain material B, wherein the method for controlling the pH value of the reaction solution comprises: maintaining the reaction solution at a first pH value of 3 for 2 h, reducing the pH value by 0.2 every 10 min, and finally controlling the residual acid concentration of the reaction solution to 0-70 g / l and continuing the reaction for 1 h, and controlling the residual acid concentration of the reaction solution as shown in Table 1;

[0052] (3) First filtration: filtering the material B to separate the slag C and the tungsten-containing liquid, washing the slag C, the washing liquid is hot water, and the temperature of the hot water is 60° C.

[0053] (4) Second slurry preparation: mixing the washed slag C with hot water, the temperature of the hot water being 100° C., to obtain material D;

[0054] (5) Leaching: adding a second reagent to the material D for reaction, wherein the second reagent is a phosphorus-sulfur mixed acid, wherein the concentration of the 75% phosphoric acid used is 25 g / l, and the concentration of the 98% sulfuric acid is 350 g / l, and the phosphorus concentration and acidity of the reaction solution are controlled to be 25 g / l and 350 g / l, respectively, and then heating leaching is performed, the heating temperature is 100° C., and the temperature is kept for 1 hour to obtain material E;

[0055] (6) Second filtration: filtering the material E to obtain a tungsten-containing enriched liquid and a filter residue.

[0056] Determine the tungsten content of the tungsten-containing liquid of step (3) and the tungsten-containing enriched liquid of step (6);

[0057] Table 1

[0058]

[0059]

[0060] It can be found from Table 1 that as the residual acid concentration of material B increases, the tungsten content of the tungsten-containing liquid increases, and the tungsten content of the filter residue after leaching also gradually increases. When the residual acid concentration of material B is controlled to be below 11 g / l and above 8 g / l, preferably below 11 g / l and above 9 g / l, the treatment effect of scheelite is the best, and the tungsten content of the filter residue is significantly reduced; excessively high residual acid concentration is likely to increase the probability of decomposition of calcium tungstate and form other substances, making it impossible to decompose in the subsequent leaching process, thereby resulting in an increase in the tungsten content in the filter residue and the filter residue, while too low a residual acid concentration makes it difficult to ensure that other impurities in material B are stably reacted by the first reagent.

[0061] Comparative Examples 1-6

[0062] The difference between these comparative examples and Examples 1-16 is that the first reagent added is washing powder, the pH value of the reaction solution is controlled at 7, and the other steps and parameters are the same; some parameter conditions and test data of Comparative Examples 1-6 are detailed in the following table:

[0063] Table 2

[0064]

[0065]

[0066] It can be found from Table 2 that when washing powder 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 washing powder is surfactant, and although surfactant has decontamination ability, it is difficult to remove impurities on the surface of the ore, the tungsten content of the tungsten-containing liquid is extremely low, and it is difficult to play an effective role in reducing tungsten loss in the subsequent leaching reaction.

[0067] Comparative Examples 7-12

[0068] The difference between these comparative examples and Examples 1-7 is that the first reagent added is 50 g / l of caustic soda flakes, the pH value of the reaction solution controlled in step (2) is controlled at 7-12, and the subsequent leaching steps and parameters are the same; some parameter conditions and test data of Comparative Examples 7-12 are detailed in the following table:

[0069] Table 3

[0070]

[0071] It can be found from Table 3 that when caustic soda is used as the first reagent to react with scheelite and the pH values ​​are controlled to be 7, 8, 9, 10, 11, and 12 respectively, as the pH value increases, scheelite will react with caustic soda as follows: CaWO4(s)+2NaOH(aq)=Na2WO4(aq)+Ca(OH)2(s), and these reaction products are difficult to decompose in subsequent reactions, which greatly increases 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, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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 comprises the following steps: (1) First slurry preparation: mixing scheelite ore with hot water to obtain material A; (2) pH adjustment: adding a first reagent to the material A to react and controlling the pH value of the reaction solution during the reaction to obtain material B, wherein the method for controlling the pH value of the reaction solution comprises: after controlling the reaction solution to a first pH value, reducing the pH value to a 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 a second time period; (3) First filtration: filtering the material B to separate the slag C and the tungsten-containing liquid, and washing the slag C; (4) Second slurry preparation: mixing the washed slag C with hot water to obtain material D; (5) Leaching: adding a second reagent to the material D to react, controlling the phosphorus concentration and acidity of the reaction solution, and then heating and leaching to obtain material E; (6) Second filtration: filtering the material E to obtain a tungsten-containing enriched liquid and a 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° C.; Preferably, the solid content of the material A is 40%-50%.

3. The method for processing scheelite ore according to claim 1, characterized in that: In step (2), the residual acid concentration in the material B is controlled to be 9-11 g / l; Preferably, in step (2), the first reagent is sulfuric acid.

4. The method for processing scheelite ore according to claim 1, characterized in that: In step (2), the first pH value is 1 to 3, and the second pH value is 0.2 to 0.

3.

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; Preferably, the temperature of the hot water is 40-90°C.

6. 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°C.

7. The method for processing scheelite ore according to claim 1, characterized in that: In step (5), the phosphorus concentration is controlled to be 20-25 g / l; Preferably, in step (5), the second reagent is a phosphorus-sulfuric acid mixture.

8. The method for processing scheelite ore according to claim 1, characterized in that: In step (5), the acidity is controlled to be 340-360 g / l; Preferably, in step (5), the second reagent is a phosphorus-sulfuric acid mixture.

9. The method for processing scheelite ore according to claim 1, characterized in that: In step (5), the heating temperature is 90-105° C., and the heating time is 0.5 to 3 hours.

10. The method for processing scheelite ore according to claim 1, characterized in that: The processing method also includes: The tungsten-containing feed solution in step (3) and the tungsten-containing enriched solution in step (6) are mixed to recover tungsten.

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