Hydroxamic acid modified starch-metal ion flocculants for tungsten ore flotation and application thereof

Abstract

The application discloses a hydroxamic acid modified starch-metal ion flocculant for tungsten ore flotation, and has the following structural formula: wherein n is an integer of 500-1000, and Me is Cu 2+ , Zn 2+ , Fe 3+ , Fe 2+ , Pb 2+ , Al 3+ , Mg 2+ or Ca 2+ . The flocculant is formed by hydroxamic acid modified macromolecular starch and metal ions, and has selectivity. The hydroxamic acid has good chelation on the metal ions, the formed complex has strong chelation on tungsten oxide, and therefore, the hydroxamic acid modified macromolecular starch can realize selective bridging of fine tungsten ore, and realize selective bridging and lengthening of tungsten ore particles, so that the flotation efficiency of tungsten oxide is greatly improved.

Description

Technical Field

[0001] This invention relates to mineral flotation, specifically to a hydroxyxamic acid-modified starch-metal ion flocculant for tungsten ore flotation and its application. Background Technology

[0002] Tungsten is a crucial strategic resource for the national economy and modern national defense. my country boasts the world's richest tungsten resources, but among the proven tungsten-bearing minerals, only scheelite and wolframite are industrially viable. Wolframite has a high specific gravity, making gravity separation a relatively low-cost method. However, gravity separation requires sophisticated equipment and has low recovery rates, making it difficult to achieve satisfactory results. Currently, flotation is widely considered one of the most effective and economical methods for recovering wolframite. Currently, wolframite accounts for 80% of my country's mined tungsten resources, while scheelite accounts for only 20%, and its grade is relatively low. Due to its similar surface chemistry and floatability to gangue minerals such as fluorite and calcite, scheelite is relatively difficult to beneficiate. Considering the recovery and utilization of useful elements, flotation is the preferred and most commonly used beneficiation method for scheelite. However, during flotation, fine tungsten particles are difficult to adhere to the surface of flotation bubbles, leading to significant separation challenges. Summary of the Invention

[0003] To address the aforementioned problem of the difficulty in flotation separation of fine-grained tungsten ore, this invention provides a hydroxyxamic acid-modified starch-metal ion flocculant for tungsten ore flotation and its application. This flocculant can selectively flocculate fine-grained tungsten ore, enabling the fine-grained tungsten ore to effectively adhere to the surface of flotation bubbles, thereby increasing the flotation rate of fine-grained tungsten ore and effectively improving resource utilization.

[0004] To achieve the above objectives, the present invention provides a hydroxyxamic acid-modified starch-metal ion flocculant for tungsten ore flotation, wherein the flocculant has the following structural formula:

[0005] ,

[0006] Where n is an integer between 500 and 1000, and Me is Cu 2+ Zn 2+ Fe 3+ Fe 2+ Pb 2+ Al 3+ Mg 2+ or Ca 2+ .

[0007] In the above-mentioned flocculant, a selective flocculant is formed by the combination of hydroxamic acid-modified macromolecular starch and metal ions. Because hydroxamic acid has a good chelating effect on the above-mentioned metal ions, the complex formed has a strong chelating effect on oxides such as tungsten ore. Thus, the macromolecular starch is used to achieve selective bridging of fine tungsten ore particles, and to achieve selective bridging and growth of tungsten ore particles, thereby greatly improving the flotation efficiency of oxidized tungsten ore.

[0008] Preferably, the degree of substitution of hydroxamic acid is 0.8 to 1.6.

[0009] Excessive substitution leads to increased reactivity of starch molecules, but decreased molecular stability and susceptibility to hydrolysis. Conversely, lower substitution results in lower reactivity and higher stability, making them less prone to hydrolysis. Therefore, controlling the amount of hydroxylamine used is crucial for controlling the endpoint of the hydroxyoxime reaction to obtain a suitable degree of substitution.

[0010] A second aspect of the present invention provides a method for preparing the above-mentioned flocculant, the method comprising the following steps:

[0011] (1) Add solvent and alkali to a high amylose solution to alkalize it and obtain an alkalized reaction solution; the solvent is an organic solvent such as methanol or ethanol, and the alkali is a sodium hydroxide or potassium hydroxide.

[0012] (2) Add chlorinated organic acid ester to the reaction solution after alkalization in step (1) and carry out etherification reaction to obtain sample solution; after the chlorinated organic acid reacts with the starch molecules after alkalization, starch molecules containing ester groups are generated, which provide raw materials for further reaction with hydroxylamine; the chlorinated organic acid can be ethyl chloroacetate, ethyl chloroformate, methyl chloroformate, methyl chloroacetate, etc.

[0013] (3) Add hydroxylamine hydrochloride solution to the sample solution in step (2) to obtain a hydroxamic acid modified starch solution; hydroxylamine reacts with starch molecules containing ester groups to generate starch molecules containing hydroxamic groups, which are convenient for combining with metal ions.

[0014] (4) Add a solution containing excess metal ions to the hydroxamic acid modified starch solution obtained in step (3), and then wash and dry to obtain the final product.

[0015] This preparation method modifies common hydroxyl-rich macromolecular starch into a flocculant containing cationic hydroxamic acid metal complexes, which changes the charge of the macromolecular agent from negative to positive, effectively promoting the flocculation of negatively charged oxide minerals.

[0016] Preferably, in step (1), the high amylose is selected from one or more of high amylose barley starch, high amylose corn starch, and high amylose potato starch. These are widely available and inexpensive.

[0017] Preferably, in step (1), the mass ratio of the high amylose starch to the alkali is (1~4):1. When the ratio is greater than 4, the alkalization effect is poor, which is not conducive to the subsequent hydroxyoxime reaction. When the ratio is less than 1, the starch is prone to hydrolysis.

[0018] Specifically, the alkalization conditions are: constant temperature alkalization at 20-40°C for 30-90 minutes, preferably at 30°C.

[0019] Preferably, in step (2), the mass ratio of ethyl chloroacetate to alkali is (1~4):1.

[0020] Specifically, in step (2), the etherification reaction conditions are: etherification reaction at 20-50℃ for 3-5 hours, and etherification reaction at 25-45℃ for 4 hours is selected.

[0021] Preferably, in step (3), the molar ratio of the etherified product to hydroxylamine is 1:(0.8~1.2). A third aspect of the invention provides the application of the above-described flocculant in tungsten ore flotation.

[0022] This method is particularly suitable for fine-grained tungsten ore with a particle size of less than 38 μm. The flocculant dosage is 200-260 g / t, and the pulp pH is 6-10. Specifically, first, add flocculant to the pulp at a dosage of 200-260 g / t to deslim it, then pour it into the flotation cell at a rotation speed of 1600-1700 r / min. Next, adjust the pulp pH to 6-10 and allow it to react for 3-5 minutes. Then, add a collector at a dosage of 300-600 g / t and allow it to react for 3-5 minutes. Finally, add a frother such as MIBC (methyl isobutyl methanol) at a dosage of 30-50 g / t and allow it to react for 2-3 minutes. A flotation process consisting of roughing, scavenging, and cleaning is employed.

[0023] Through the above technical solution, the present invention achieves the following beneficial effects:

[0024] The hydroxamic acid-modified starch-metal ion flocculant of the present invention has a strong selective flocculation effect on fine-grained tungsten ore, especially fine-grained tungsten ore smaller than 38 μm, effectively improving the floatability of fine-grained tungsten ore. The complex formed therein has extremely strong chelating properties for tungsten oxide ore, thereby utilizing macromolecular starch to achieve selective bridging of fine-grained tungsten ore, realizing selective bridging and growth of tungsten ore particles, and thus greatly improving the flotation efficiency. Attached Figure Description

[0025] Figure 1 This is a flow chart of the tungsten ore flotation process in an embodiment of the present invention. Detailed Implementation

[0026] The specific embodiments of the present invention will be described in detail below with reference to examples. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0027] In the following examples, the raw ore is an actual mine from a mine in Henan Province, with a tungsten grade of 0.15. The main minerals are scheelite and wolframite, and the gangue minerals include quartz, fluorite, feldspar, calcite, and apatite. The particle size of the tungsten ore is mainly below 38 μm.

[0028] Example 1

[0029] 5 g of sodium hydroxide and 20 g of high amylose barley starch were added to 200 mL of 85% ethanol aqueous solution and alkalized at 20 °C for 90 min under magnetic stirring. Then, 20 g of ethyl chloroacetate was added and the temperature was raised to 20 °C for 5 h of etherification reaction. After the etherification reaction was completed, the mixture was filtered, and 50 mL of hydroxylamine hydrochloride solution was added to the filter residue and the pH was adjusted to 8 with sodium hydroxide solution. Then, lead nitrate solution containing 0.5 mol of lead ions was added at 50 °C to react. Finally, the mixture was washed with anhydrous ethanol and dried to obtain a flocculant formed by hydroxamic acid modified starch and metallic lead ions.

[0030] like Figure 1 As shown, 200g of actual ore was repeatedly wet-milled using a rod mill (particle size after milling less than 38μm, media filling rate 30%). 200g / t of the aforementioned flocculant was added, and after one desliming process, the ore was poured into a 0.75 L flotation cell. An appropriate amount of water was added, and the pulp pH was adjusted to 8. Then, 500g / t of benzoyl oxime collector was added, followed by 30g / t of MIBC frother. After stirring for 3 minutes, frothing was started and carried out for 5 minutes. A roughing-scavenging-cleaning process was performed, with the middlings returned to the roughing phase in a closed-loop flotation process. The tungsten concentrate was scraped to the concentrate basin with the froth, and the tailings remained in the flotation cell. The concentrate and tailings were filtered, dried, and weighed. The grade of the concentrate was tested, and the recovery rate was calculated. The results are shown in Table 1.

[0031] Example 2

[0032] 13g of sodium hydroxide and 39g of high amylose corn starch were added to 300 mL of 80% methanol aqueous solution and alkalized at 40℃ for 60 min under magnetic stirring. Then, 39g of methyl chloroacetate was added and the temperature was raised to 45℃ for 4 h for etherification. After the etherification reaction was completed, the mixture was filtered, and 95 mL of hydroxylamine hydrochloride solution was added to the filter residue to adjust the pH to 8. Then, ferric nitrate solution containing 0.5 mol of iron ions was added at 50℃ to react. Finally, the mixture was washed with anhydrous ethanol and dried to obtain a flocculant formed by hydroxamic acid modified starch and metallic iron ions.

[0033] 200g of actual ore was repeatedly wet-milled using a rod mill (particle size after milling less than 38 μm, media filling rate 30%). 230g / t of the aforementioned flocculant was added, and after one desliming process, the ore was poured into a 0.75 L flotation cell. An appropriate amount of water was added, and the pulp pH was adjusted to 6. Then, 300g / t of benzoyl oxime collector was added, followed by 40g / t of MIBC frother. After stirring for 3 minutes, frothing was started and carried out for 5 minutes. A roughing-scavenging-cleaning process was performed, with the middlings returned to the roughing phase in a closed-loop flotation process. The tungsten concentrate was scraped to the concentrate basin with the froth, while the tailings remained in the flotation cell. The concentrate and tailings were filtered, dried, and weighed. The concentrate grade was tested, and the recovery rate was calculated. The results are shown in Table 1.

[0034] Example 3

[0035] 13g of sodium hydroxide and 13g of high amylose potato starch were added to 300 mL of 90% ethanol aqueous solution and alkalized at 30°C for 70 min under magnetic stirring. Then, 13g of ethyl chloroformate was added and the temperature was raised to 35°C for 3 h of etherification reaction. After the etherification reaction was completed, the mixture was filtered, and 75 mL of hydroxylamine hydrochloride solution was added to the filter residue to adjust the pH to 8. Then, zinc nitrate solution containing 0.5 mol of zinc ions was added at 50°C to react. Finally, the mixture was washed with anhydrous ethanol and dried to obtain a flocculant formed by hydroxamic acid modified starch and metallic zinc ions.

[0036] 200g of actual ore was repeatedly wet-milled using a rod mill (particle size after milling less than 38 μm, media filling rate 30%). 260g / t of the aforementioned flocculant was added, and after one desliming process, the ore was poured into a 0.75 L flotation cell. An appropriate amount of water was added, and the pulp pH was adjusted to 10. Then, 600g / t of benzoyl oxime acid collector was added, followed by 50g / t of MIBC frother. After stirring for 3 minutes, frothing was started and continued for 5 minutes. A roughing-scavenging-cleaning process was performed, with the middlings returned to the roughing phase in a closed-loop flotation process. The tungsten concentrate was scraped to the concentrate basin with the froth, while the tailings remained in the flotation cell. The concentrate and tailings were filtered, dried, and weighed. The concentrate grade was tested, and the recovery rate was calculated. The results are shown in Table 1.

[0037] Comparative Example 1

[0038] 200g of actual ore was repeatedly wet-milled using a rod mill (milling until mineral particles smaller than 38 μm accounted for 80%, and the media filling rate was 30%). After adding an appropriate amount of water and stirring for 4 minutes, a pH adjuster was added to adjust the pulp pH to 8, and the reaction time was 3 minutes. Then, 600 g / t of benzohydroxyxamic acid collector was added, and the reaction time was 3 minutes. Finally, 50 g / t of MIBC frother was added, and after stirring for 2 minutes, frothing was started and frothing was carried out for 5 minutes. A roughing-scavenging-cleaning process was performed, with the middlings returned to the roughing flotation closed-loop process. Tungsten concentrate was scraped to the concentrate basin with the froth, and tailings remained in the flotation cell. The concentrate and tailings were filtered, dried, and weighed. The grade of the concentrate was tested, and the recovery rate was calculated. The results are shown in Table 1.

[0039] Table 1. Tungsten grade and tungsten recovery rate in the examples and comparative examples.

[0040]

[0041] As shown in Table 1, the flocculants formed by hydroxamic acid-modified starch and different metal ions have a good selective flocculation effect on fine-grained tungsten ore. The tungsten grade of the tungsten concentrate is above 5.69%, which is much higher than that of the tungsten concentrate obtained by the conventional flotation method in Comparative Example 1. Among them, the flocculant formed with lead ions has the best effect, with a tungsten grade of 11.25%. For fine-grained tungsten ore smaller than 38 μm, the flocculant formed by hydroxamic acid-modified starch and metal ions in this invention has excellent selective flocculation effect and can significantly improve the flotation efficiency of oxidized tungsten ore.

[0042] The preferred embodiments of the present invention have been described in detail above with reference to the examples. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0043] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0044] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A tungsten ore flotation method using hydroxamic acid-modified starch-metal ion flocculant, characterized in that, The flocculant has the following structural formula: ， Where n is an integer between 500 and 1000, and Me is Cu 2+ Zn 2+ Fe 3+ Fe 2+ Pb 2+ Al 3+ Mg 2+ or Ca 2+ .

2. The flocculant according to claim 1, characterized in that, The degree of substitution of hydroxamic acid is 0.8 to 1.

6.

3. The method for preparing the flocculant according to claim 1 or 2, characterized in that, Includes the following steps: (1) Add solvent and alkali to a high amylose solution to alkalize it and obtain an alkalized reaction solution, wherein the amylose content in the high amylose is ≥50%; (2) Add chlorinated organic acid esters to the reaction solution after alkalization in step (1) to carry out etherification reaction and obtain sample solution; (3) Add hydroxylamine hydrochloride solution to the sample solution in step (2) to obtain hydroxamic acid modified starch solution; (4) Add a solution containing metal ions to the hydroxamic acid modified starch solution obtained in step (3), and then wash and dry to obtain the final product.

4. The preparation method according to claim 3, characterized in that, In step (1), the high amylose is selected from one or more of high amylose barley starch, high amylose corn starch and high amylose potato starch.

5. The preparation method according to claim 3, characterized in that, In step (1), the mass ratio of the high amylose to alkali is (1~4):

1.

6. The preparation method according to claim 3, characterized in that, In step (1), the alkalization conditions are: constant temperature alkalization at 20-40℃ for 30-90 minutes.

7. The preparation method according to claim 3, characterized in that, In step (2), the mass ratio of ethyl chloroacetate to alkali is (1~4):1, and the etherification reaction conditions are: etherification reaction at 20~50℃ for 3~5h.

8. The preparation method according to claim 3, characterized in that, In step (3), the molar ratio of the etherified product to hydroxylamine is 1:(0.8~1.2).

9. The application of the flocculant according to claim 1 or 2 in the flotation of tungsten ore.

10. The application according to claim 9, characterized in that, The tungsten ore particle size is less than 38 μm, the flocculant dosage is 200~260 g / t, and the pH of the slurry is 6~10.

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