Beneficiation depressant and use thereof

Abstract

The present application relates to a kind of mineral processing depressant, belong to mineral flotation technical field, to solve one of the problems such as poor universality of existing starch depressant, poor flotation effect, low concentrate grade, low recovery rate etc..The mineral processing depressant includes sulfonated starch and carboxylated starch, according to mass ratio, sulfonated starch: carboxylated starch = 1:0.3~3.Conventional natural starch belongs to the polymer flotation depressant containing -OH, the present application is by converting the hydroxyl group in natural starch inhibitor into carboxyl and sulfonic acid group, -OH is more hydrophilic than carboxyl and sulfonic acid group, while the molecular weight of modified starch is smaller, reduce the adsorption capacity of starch on the surface of the target mineral, without affecting the adsorption on the surface of calcium magnesium mineral, so as to improve the selectivity of mineral flotation.

Description

Technical Field

[0001] This invention relates to the field of mineral flotation technology, and in particular to a mineral processing inhibitor and its application. Background Technology

[0002] Currently, my country's mineral resources are characterized by "abundance of lean ore, scarcity of rich ore, and fine particle size," making efficient separation difficult and hindering further processing. Flotation is a crucial method for the efficient separation of fine-particle mineral resources. However, due to the similar surface properties of gangue minerals and target minerals, traditional fatty acid collectors alone are insufficient for efficient separation; suitable depressants are needed to improve flotation efficiency. Therefore, developing green, environmentally friendly, and highly selective depressants is of profound significance.

[0003] Starch is a natural high-molecular-weight organic compound widely used in food, wastewater treatment, and mineral processing due to its environmentally friendly, readily available, and inexpensive properties. Starch is derived from numerous glucose monomers condensed through glycosidic bonds. Its hydroxyl groups have a strong affinity for Fe, making it commonly used in reverse flotation desilication processes. However, the starch molecule contains only the hydroxyl group, resulting in poor selective adsorption to mineral surfaces. This significantly reduces the floatability of the target mineral while inhibiting gangue minerals, leading to low mineral separation efficiency. Therefore, it is crucial to modify starch to improve the difference in floatability between the target mineral and gangue minerals.

[0004] Among various modifications, hydrophilic modification has attracted much attention. By introducing highly selective and strongly polar functional groups into its molecular structure, it is beneficial to achieve selective bonding with specific active sites on the mineral surface, while also endowing it with new properties such as good water solubility, dispersibility, hydrophilicity, and selectivity. However, the versatility of currently studied modified starch is relatively poor, limiting its widespread use in the field of mineral processing. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a mineral processing inhibitor and its application to solve one of the problems of poor universality, poor flotation effect, low concentrate grade, and low recovery rate of existing modified starch inhibitors.

[0006] In a first aspect, the present invention provides a mineral processing inhibitor comprising sulfonated starch and carboxylated starch, wherein the mass ratio of sulfonated starch to carboxylated starch is 1:0.3 to 3.

[0007] Furthermore, the sulfonated starch is prepared by the following method:

[0008] (1) Disperse natural starch in ethanol, activate it under ultrasonic treatment, and dry it to obtain activated starch;

[0009] (2) Mix ethanol and ammonium sulfate, then add concentrated sulfuric acid and the activated starch in sequence to carry out the reaction, adjust the pH value to 8.5-10.5, and obtain crude sulfonated starch product;

[0010] (3) The crude sulfonated starch product is dialyzed, dried and ground to obtain the sulfonated starch.

[0011] Furthermore, in step (1), the ultrasonic power is 250-300W and the ultrasonic time is 2-8min.

[0012] Furthermore, in step (2), the volume fraction of ethanol is ≥80%, and the volume-to-mass ratio of ethanol, ammonium sulfate, concentrated sulfuric acid and activated starch is 35.0~40.0mL:0.8~1.2g:24.0~28.0mL:1.5~2.5g.

[0013] Furthermore, the carboxylated starch is prepared by the following method:

[0014] (I) React natural starch and acetic acid solution at 70-90℃ for 2-10 hours to obtain solution A;

[0015] (II) Hydrogen peroxide is slowly added dropwise to solution A, and the reaction is carried out at 60-90°C for 1-5 hours. The pH is adjusted to neutral, and the solution is dried to obtain the carboxylated starch.

[0016] Furthermore, in step (I), the natural starch is corn starch, and the mass concentration of the acetic acid solution is 1-10%.

[0017] Furthermore, in step (I), the mass-to-volume ratio of natural starch to acetic acid solution is 1 g: 20–40 mL.

[0018] Furthermore, in step (II), the volume ratio of hydrogen peroxide to acetic acid solution is 1 / 10 to 1 / 2.

[0019] Secondly, the present invention provides a method for preparing the aforementioned mineral processing inhibitor, comprising preparing carboxylated starch and sulfonated starch separately, and then mixing the carboxylated starch and sulfonated starch to obtain the aforementioned mineral processing inhibitor.

[0020] Thirdly, the present invention provides an application of the above-mentioned mineral processing inhibitor in the flotation of calcium-magnesium gangue minerals.

[0021] Furthermore, the calcium-magnesium gangue minerals mentioned are forsterite or calcite.

[0022] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0023] (1) The starch inhibitor of the present invention contains -OH. The hydrophilicity of -OH is stronger than that of carboxyl and sulfonic acid groups. When the hydroxyl groups in starch are converted into carboxyl and sulfonic acid groups, the hydrophilicity of the groups becomes weaker, reducing the adsorption capacity of starch on the surface of the target mineral, without affecting the adsorption on the surface of calcium and magnesium minerals, thereby improving the flotation selectivity of minerals.

[0024] (2) When starch contains both carboxyl and sulfonic acid groups, the sulfonic acid groups on the carbon chain are bonded to the calcium and magnesium sites on the surface of calcium and magnesium minerals through oxygen atoms. The carboxyl groups are bonded to the remaining magnesium sites on the surface of gangue minerals in the form of "holes", which makes up for the steric hindrance defects of the sulfonic acid groups and forms a specific spatial matching structure, so that it selectively acts on the surface of calcium and magnesium gangue minerals. The oxygen atoms in the molecule that are not bonded to the mineral surface combine with water molecules to produce hydration. The flexible carboxyl groups are more likely to bridge with the sulfonic acid groups (or carboxyl groups) through hydrogen bonding to form a stable network structure, giving it stronger hydrophilic properties, hindering the adsorption of collectors on the calcium and magnesium surface, inhibiting the flotation of calcium and magnesium minerals, and improving the flotation of the target minerals.

[0025] (3) The inhibitor of the present invention has strong universality and can be used in calcium-magnesium gangue minerals. It can selectively inhibit calcium-magnesium minerals and improve the grade and recovery rate of the target minerals.

[0026] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objectives and other advantages of this invention can be realized and obtained through the specific points highlighted in the description. Detailed Implementation

[0027] One specific embodiment of the present invention discloses a mineral processing inhibitor comprising sulfonated starch and carboxylated starch, wherein the mass ratio of sulfonated starch to carboxylated starch is 1:0.3-3.

[0028] In one specific embodiment, the average molecular weight of carboxylated starch is 100-2000 Da, and the average molecular weight of sulfonated starch is 100-2000 Da.

[0029] In one specific embodiment, the sulfonated starch is prepared by the following method:

[0030] (1) Disperse natural starch in ethanol, activate it under ultrasonic treatment, and dry it to obtain activated starch;

[0031] (2) Mix ethanol and ammonium sulfate, then add concentrated sulfuric acid and the activated starch in sequence to carry out the reaction, adjust the pH value to 8.5-10.5, and obtain crude sulfonated starch product;

[0032] (3) The crude sulfonated starch product is dialyzed, dried and ground to obtain the sulfonated starch.

[0033] In one specific implementation, in step (1), the ultrasonic power is 250-300W and the ultrasonic time is 2-8min.

[0034] In a preferred embodiment, in step (1), the natural starch is corn starch, the volume concentration of ethanol is 10-30%, and the volume-to-mass ratio of ethanol to natural starch is 35.0-40.0 mL: 1.5-2.5 g. It should be noted that the natural starch is activated to disrupt its crystal structure and improve the reaction efficiency of the reactive agent.

[0035] In one specific embodiment, in step (2), the volume fraction of ethanol is ≥80%, and the volume-to-mass ratio of ethanol, ammonium sulfate, concentrated sulfuric acid and activated starch is 35.0~40.0mL:0.8~1.2g:24.0~28.0mL:1.5~2.5g.

[0036] It should be noted that the amount of concentrated sulfuric acid, ethanol concentration, and dosage are key factors. When concentrated sulfuric acid is used as a sulfonating agent, excessive concentration will cause starch carbonization, while insufficient concentration will reduce sulfonation efficiency and extraction rate. Ethanol, as an organic diluent, primarily serves to dilute the concentrated sulfuric acid.

[0037] Specifically, in step (2), concentrated sulfuric acid is added drop by drop while stirring. After the solution temperature is kept constant at 0°C, activated starch is added.

[0038] In one specific implementation, in step (2), the reaction temperature is -10 to 10°C and the reaction time is 2 to 10 hours.

[0039] In one specific implementation, in step (2), a NaOH solution with a concentration of 0.5 to 1.5 mol / L is used to adjust the pH value.

[0040] It should be noted that in step (3), the crude sulfonated starch product is placed in a dialysis bag with a molecular weight cutoff of 100-2000 Da, and repeatedly dialyzed with ultrapure water to remove unreacted ethanol, sulfuric acid, and ammonium sulfate. After freeze-drying and grinding into powder, the sulfonated starch is obtained.

[0041] In one specific embodiment, the carboxylated starch is prepared by the following method:

[0042] (I) React natural starch and acetic acid solution at 70-90℃ for 2-10 hours to obtain solution A;

[0043] (II) Hydrogen peroxide is slowly added dropwise to solution A, and the reaction is carried out at 60-90°C for 1-5 hours. The pH is adjusted to neutral, and the solution is dried to obtain the carboxylated starch.

[0044] In one specific embodiment, in step (I), the natural starch is corn starch, and the mass concentration of the acetic acid solution is 1-10%.

[0045] In one specific embodiment, in step (I), the mass-to-volume ratio of natural starch to acetic acid solution is 1 g: 20-40 mL.

[0046] In one specific embodiment, in step (II), the volume ratio of hydrogen peroxide to acetic acid solution is 1 / 10 to 1 / 2.

[0047] Another specific embodiment of the present invention discloses a method for preparing the aforementioned mineral processing inhibitor, comprising preparing carboxylated starch and sulfonated starch separately, and then mixing the carboxylated starch and sulfonated starch to obtain the aforementioned mineral processing inhibitor.

[0048] In a preferred embodiment, sulfonated starch and carboxylated starch are mixed at a mass ratio of 1:0.3 to 3.

[0049] The collector described in this invention is sodium oleate or salicylic acid.

[0050] Another specific embodiment of the present invention discloses an application of the above-mentioned mineral processing inhibitor in the flotation of calcium-magnesium gangue minerals.

[0051] In a preferred embodiment, the calcium-magnesium gangue mineral is forsterite or calcite.

[0052] In a preferred embodiment, the forsterite is a synthetic mixture of ilmenite and forsterite or olivine-pyroxene type ilmenite, and the calcite is fine-grained cassiterite.

[0053] The mineral processing inhibitors described in this invention have a certain inhibitory effect on calcium magnesium gangue minerals, but a smaller inhibitory effect on ilmenite or cassiterite.

[0054] Compared to existing technologies, conventional natural starch, due to its high molecular weight and long carbon chain skeleton, exhibits poor selectivity for oxidized minerals during adsorption onto ilmenite, cassiterite, forsterite, and calcite. While the hydrophilic OH groups adsorb onto the active sites on the mineral surface, the longer carbon chains also coat the vicinity of the mineral surface, hindering further adsorption of the collector on the ilmenite or cassiterite surface. Therefore, natural starch has poor selectivity for oxidized minerals. However, after natural starch depolymerizes into smaller molecules (sulfonated or carboxylated), the carbon chain skeleton shortens. The shorter carbon chain skeleton has weaker adsorption near the mineral surface, allowing the collector to compete for adsorption on the ilmenite / cassiterite surface, ultimately achieving selective inhibition of calcium and magnesium mineral flotation by the smaller molecule starch.

[0055] When sulfonated or carboxylated starch is prepared using the method of this invention, some hydroxyl groups are converted to sulfonic acid groups after sulfonation, but not all of them are converted; after carboxylation, some hydroxyl groups are converted to carboxyl groups, but not all of them are converted. The starch containing the inhibitor of this invention contains -OH groups, which are more hydrophilic than carboxyl and sulfonic acid groups. When some of the hydroxyl groups in the starch are converted to carboxyl and sulfonic acid groups, the hydrophilicity of the groups weakens, reducing the adsorption capacity on the surface of ilmenite or cassiterite, without affecting the adsorption on the surface of calcium magnesium minerals, thereby improving the grade of the target mineral.

[0056] When starch contains both carboxyl and sulfonic acid groups, the sulfonic acid groups on the carbon chain bond to the calcium and magnesium sites on the surface of calcium and magnesium minerals through oxygen atoms. The carboxyl groups, in the form of "sockets," bind to the remaining magnesium sites on the surface of gangue minerals, compensating for the steric hindrance defects of the sulfonic acid groups and forming a specific spatial matching structure, which allows it to selectively act on the surface of calcium and magnesium gangue minerals. The oxygen atoms in the molecule that are not bonded to the mineral surface combine with water molecules to produce hydration. The flexible carboxyl groups are more likely to bridge with the sulfonic acid groups (or carboxyl groups) through hydrogen bonding to form a stable network structure, giving it stronger hydrophilic properties, hindering the adsorption of collectors on the calcium and magnesium surface, inhibiting the flotation of calcium and magnesium minerals, and improving the flotation selectivity of the target mineral.

[0057] This invention improves the flotation selectivity of minerals by converting the hydroxyl groups in natural starch inhibitors into carboxyl and sulfonic acid groups. The -OH group is more hydrophilic than the carboxyl and sulfonic acid groups. At the same time, the modified starch has a smaller molecular weight, which reduces the adsorption capacity of starch on the surface of the target mineral without affecting the adsorption on the surface of calcium and magnesium minerals.

[0058] The technical solution of the present invention will be further explained below with reference to specific embodiments.

[0059] Example 1

[0060] This embodiment describes the preparation of sulfonated starch, including the following steps:

[0061] (1) Disperse corn starch in ethanol with a volume concentration of 20% as the dispersion medium. The volume mass ratio of ethanol to corn starch is 35.0 mL: 1.5 g. Under ultrasonic power of 300 W, the corn starch is ultrasonically activated for 3 min and then dried to obtain activated starch.

[0062] (2) Place a 100 mL three-necked round-bottom flask in an ice-water bath and add 37.34 mL of anhydrous ethanol solution. Stir magnetically for 1 min, then add 1.0 g of ammonium sulfate and stir magnetically to obtain a homogeneous solution. Add 26.67 mL of concentrated sulfuric acid dropwise to the solution while stirring. After the solution temperature is constant at 0 °C, add 2.0 g of activated starch. Control the reaction temperature at 0 °C and the reaction time at 10 h. Terminate the reaction and adjust the pH of the system to 10.0 with 1.0 mol / L NaOH solution to obtain crude sulfonated starch product.

[0063] (3) The crude sulfonated starch product is placed in a dialysis bag with a molecular weight cutoff of 500 Da and repeatedly dialyzed with ultrapure water to remove unreacted ethanol, sulfuric acid and ammonium sulfate. After freeze drying, it is ground into powder to obtain the sulfonated starch.

[0064] Example 2

[0065] This embodiment describes the preparation of sulfonated starch, including the following steps:

[0066] (1) Corn starch was dispersed in ethanol with a volume concentration of 10% as the dispersion medium. The volume mass ratio of ethanol to corn starch was 37.0 mL: 2 g. The corn starch was activated by ultrasonic treatment under ultrasonic power of 250 W for 5 min and then dried to obtain activated starch.

[0067] (2) Place a 100 mL three-necked round-bottom flask in an ice-water bath and add 40 mL of 80% ethanol solution. Stir magnetically for 3 min, then add 1.2 g of ammonium sulfate and stir magnetically to obtain a homogeneous solution. Add 24 mL of concentrated sulfuric acid dropwise to the solution while stirring. After the solution temperature is constant at 0 °C, add 2.5 g of activated starch. Control the reaction temperature at 0 °C and the reaction time at 6 h. Terminate the reaction and adjust the pH of the system to 9.5 with 0.5 mol / L NaOH solution to obtain crude sulfonated starch product.

[0068] (3) The crude sulfonated starch product is placed in a dialysis bag with a molecular weight cutoff of 1000 Da and repeatedly dialyzed with ultrapure water to remove unreacted ethanol, sulfuric acid and ammonium sulfate. After freeze drying, it is ground into powder to obtain the sulfonated starch.

[0069] Example 3

[0070] This embodiment describes the preparation of sulfonated starch, including the following steps:

[0071] (1) Corn starch was dispersed in ethanol with a volume concentration of 30% as the dispersion medium. The volume mass ratio of ethanol to corn starch was 40.0 mL: 2.5 g. The corn starch was activated by ultrasonic treatment under ultrasonic power of 285 W for 8 min and then dried to obtain activated starch.

[0072] (2) Place a 100 mL three-necked round-bottom flask in an ice-water bath, add 35 mL of anhydrous ethanol solution, stir magnetically for 3 min, then add 0.5 g of ammonium sulfate and stir magnetically to obtain a homogeneous solution. Add 28 mL of concentrated sulfuric acid dropwise to the solution while stirring. After the solution temperature is constant at -10℃, add 1.5 g of activated starch, control the reaction temperature at 10℃, and the reaction time at 2 h. Terminate the reaction, and adjust the pH of the system to 8.5 with 1.5 mol / L NaOH solution to obtain crude sulfonated starch product.

[0073] (3) The crude sulfonated starch product is placed in a dialysis bag with a molecular weight cutoff of 2000 Da and repeatedly dialyzed with ultrapure water to remove unreacted ethanol, sulfuric acid and ammonium sulfate. After freeze drying, it is ground into powder to obtain the sulfonated starch.

[0074] Example 4

[0075] The method for preparing carboxylated starch according to this embodiment includes the following steps:

[0076] (I) 2.0 g of corn starch and 20 mL of 10% acetic acid solution were reacted at 70 °C for 2 h to obtain solution A;

[0077] (II) 4 mL of hydrogen peroxide was slowly added dropwise to solution A, and the reaction was carried out at 90 °C for 1 h for 2 h. The pH was adjusted to neutral with 0.1% sodium hydroxide solution. The oxidation product was freeze-dried to obtain the carboxylated starch, which has an average molecular weight of 2000 Da.

[0078] Example 5

[0079] The method for preparing carboxylated starch according to this embodiment includes the following steps:

[0080] (I) 4.0 g of corn starch and 160 mL of 5% acetic acid solution were reacted at 80 °C for 10 h to obtain solution A;

[0081] (II) 40 mL of hydrogen peroxide was slowly added dropwise to solution A, and the reaction was carried out at 60 °C for 5 h for 4 h. The pH was adjusted to neutral with 0.1% sodium hydroxide solution. The oxidation product was freeze-dried to obtain the carboxylated starch, which has an average molecular weight of 500 Da.

[0082] Example 6

[0083] The method for preparing carboxylated starch according to this embodiment includes the following steps:

[0084] (I) 2.0 g of corn starch and 60 mL of 10% acetic acid solution were reacted at 90 °C for 6 h to obtain solution A;

[0085] (II) 30 mL of hydrogen peroxide was slowly added dropwise to solution A, and the reaction was carried out at 80 °C for 3 h for 5 h. The pH was adjusted to neutral with 0.1% sodium hydroxide solution. The oxidation product was freeze-dried to obtain the carboxylated starch, which has an average molecular weight of 1200 Da.

[0086] Experimental Example 1

[0087] The inhibitors used in this experiment are the sulfonated starch prepared in Example 1 (denoted as A) and the carboxylated starch prepared in Example 4 (denoted as B).

[0088] This experiment demonstrates the flotation of an artificially mixed mineral of ilmenite and forsterite. The specific experimental procedure is as follows: 1.5 g of pure ilmenite and 1.5 g of pure forsterite were weighed and uniformly mixed, then dispersed in an acrylic flotation cell containing 60 mL of deionized water. The original grade of the mixed ore was 25%. The pH was adjusted to 5.5 with a suitable concentration of sulfuric acid solution, and the mixture was stirred thoroughly for 3 minutes. A certain amount of 0.5% inhibitor solution (specific addition amounts are shown in Table 1) was added to the flotation cell, and the mixture was stirred for 3 minutes. Then, 80 mg / L sodium oleate collector was added, stirred for 3 minutes, and the flotation time was 3 minutes. The flotation results are shown in Table 1.

[0089] Table 1. Effects of inhibitor type and dosage on the flotation results of artificially mixed minerals of ilmenite and forsterite.

[0090]

[0091]

[0092] As shown in Table 1, when only acid and collector are added, without depressant, the collector mainly reacts with ilmenite and has a weaker effect on calcium and magnesium minerals. Therefore, it can still increase the grade of ilmenite, but to a small extent, resulting in a low grade of ilmenite concentrate. Adding depressant further increases the grade of ilmenite concentrate.

[0093] Both inhibitors (A and B) showed some inhibitory effect on the mixed minerals. With increasing inhibitor dosage, the grade of ilmenite concentrate increased, while the recovery rate decreased. For example, when inhibitor A was used at 5 mg / L, the ilmenite concentrate grade was 38.46%, and the recovery rate was 73.84%; when inhibitor B was used at 5 mg / L, the grade was 38.88%, and the recovery rate was 74.01%; when both inhibitors A and B were used at 2.5 mg / L, the grade was 39.59%, and the recovery rate was 76.01%, indicating that the combined inhibitors had a synergistic effect on the separation of mixed ilmenite minerals. Under comparable dosages, when the ratio of the two inhibitors was 1:1, 1:2, and 2:1, the results showed that a 1:1 ratio resulted in the highest ilmenite concentrate grade and recovery rate, indicating better separation performance.

[0094] The inventors also conducted the above-mentioned experiments on sulfonated starch and carboxylated starch prepared in other embodiments, and the results were basically the same. Due to space limitations, they will not be listed one by one.

[0095] Experimental Example 2

[0096] The inhibitors used in this experiment are the sulfonated starch (denoted as A) prepared in Example 2 and the carboxylated starch (denoted as B) prepared in Example 5.

[0097] This embodiment describes the flotation of fine-grained ilmenite ore. The specific experimental procedure is as follows: An XFGⅡ type hanging-tank flotation machine with a flotation cell volume of 0.75L was used for the actual flotation test of fine-grained ilmenite ore. The process involved a single roughing stage. The grade of the fine-grained ilmenite ore was 18%, with a yield of 60% for the -74µm particle size and 15% for the -38µm particle size. 225g of actual ore (pulp concentration of 30%) was placed in the flotation cell, and the pH was adjusted to 5.0 with 5% sulfuric acid. The mixture was stirred for 5 minutes, followed by the addition of inhibitors (dosage shown in Table 2) and collector sodium oleate, each stirred for 5 minutes. The total flotation time was 5 minutes, and the stirring speed was fixed at 2300 r / min. After filtration and drying, the mass of the concentrate and tailings was accurately weighed, the grade was analyzed, and the yield and recovery rate were calculated. The results are shown in Table 2.

[0098] Table 2. Effects of inhibitor type and dosage on the flotation results of fine-grained ilmenite.

[0099]

[0100] As shown in Table 2, for a certain inhibitor, the grade of ilmenite concentrate increases while the recovery rate decreases with increasing inhibitor dosage. When inhibitors A and B are mixed in a 1:1 ratio at the same dosage, the separation effect on fine-grained ilmenite is better than that of a single inhibitor, indicating that the combined inhibitors have a synergistic effect on the separation of fine-grained ilmenite.

[0101] The inventors also conducted the above-mentioned experiments on sulfonated starch and carboxylated starch prepared in other embodiments, and the results were basically the same. Due to space limitations, they will not be listed one by one.

[0102] Experimental Example 3

[0103] The inhibitors used in this experiment are the sulfonated starch (denoted as A) prepared in Example 3 and the carboxylated starch (denoted as B) prepared in Example 6.

[0104] This experiment demonstrates the flotation of fine-grained ilmenite ore. The experimental procedure is as follows: An XFGⅡ type hanging-cell flotation machine with a flotation cell volume of 0.75L was used for the flotation of actual fine-grained ilmenite ore, employing a single roughing process. The grade of the fine-grained ilmenite ore was 18%, with a yield of over 90% for the -74µm particle size and a yield of 40-50% for the -38µm particle size. 225g of actual ore (pulp concentration of 30%) was placed in the flotation cell, and the pH was adjusted to 5.0 with 5% sulfuric acid. The mixture was stirred for 5 minutes, followed by the sequential addition of depressant (dosage shown in Table 3) and collector sodium oleate, each stirred for 5 minutes. The total flotation time was 5 minutes, and the stirring speed was fixed at 2300 r / min. After filtration and drying, the concentrate and tailings were accurately weighed, their grades were analyzed, and their yields and recoveries were calculated. The results are shown in Table 3.

[0105] Table 3. Effects of inhibitor type and dosage on the flotation results of fine-grained ilmenite.

[0106]

[0107]

[0108] As shown in Table 3, for a certain inhibitor, as the inhibitor dosage increases, the grade of fine-grained ilmenite concentrate increases, while the recovery rate decreases. Under the same dosage conditions, when inhibitors A and B are mixed in a 1:1 ratio, the separation effect on fine-grained ilmenite is better than that of a single inhibitor, indicating that the combined inhibitors have a synergistic effect on the separation of fine-grained ilmenite.

[0109] The inventors also conducted the above-mentioned experiments on sulfonated starch and carboxylated starch prepared in other embodiments, and the results were basically the same. Due to space limitations, they will not be listed one by one.

[0110] Test Example 4

[0111] The inhibitors used in this experiment are the sulfonated starch prepared in Example 1 (denoted as A) and the carboxylated starch prepared in Example 4 (denoted as B).

[0112] This experimental example demonstrates the flotation of fine-grained ilmenite ore. The experimental procedure is as follows: An XFGⅡ type hanging-cell flotation machine with a flotation cell volume of 0.75L was used for the flotation of actual fine-grained ilmenite ore, following a roughing-cleaning process. The grade of the fine-grained ilmenite ore was 18%, with a yield of over 90% for the -74µm particle size and a yield of 40-50% for the -38µm particle size. 225g of actual ore (pulp concentration of 30%) was placed in the flotation cell, and the pH was adjusted to 5.0 with 5% sulfuric acid. The mixture was stirred for 5 minutes, followed by the sequential addition of depressant and collector sodium oleate, each stirred for 5 minutes. The total flotation time was 5 minutes, and the stirring speed was fixed at 2300 r / min. The flotation yielded a rougher concentrate and tailings. The rough concentrate was further refined by adding sulfuric acid to adjust the pH to 4-5, resulting in refined concentrate and refined tailings. The refined concentrate is the final concentrate. The concentrate grade was analyzed, and its yield and recovery rate were calculated. The results are shown in Table 4.

[0113] Table 4. Effects of inhibitor type and dosage on the flotation results of fine-grained ilmenite.

[0114]

[0115]

[0116] As shown in Table 4, for a certain inhibitor, with the increase of inhibitor dosage, the grade of fine-grained ilmenite concentrate increases, while the recovery rate decreases. Under the same dosage, when inhibitors A and B are mixed in a 1:1 ratio, the separation effect on fine-grained ilmenite is better than that of a single inhibitor. When the combined inhibitor dosage is greater than 50 mg / L, a concentrate product with a ilmenite concentrate content greater than 45% can be obtained, indicating that the combined inhibitor has a synergistic effect on the separation of fine-grained ilmenite.

[0117] The inventors also conducted the above-mentioned experiments on sulfonated starch and carboxylated starch prepared in other embodiments, and the results were basically the same. Due to space limitations, they will not be listed one by one.

[0118] Experimental Example 5

[0119] The inhibitors used in this experiment are the sulfonated starch prepared in Example 1 (denoted as A) and the carboxylated starch prepared in Example 4 (denoted as B).

[0120] This experiment demonstrates the flotation of fine cassiterite. The specific experimental procedure is as follows: A 0.75L XFGⅡ type hanging trough flotation machine was used for the flotation of fine cassiterite, with a single roughing process. The grade of the raw cassiterite was 0.3%, with a yield of 80% for the -74μm particle size and 45% for the -38μm particle size. A certain amount of raw cassiterite was prepared into a 40% slurry and placed in the flotation cell. The pH was adjusted to 8.0 with 5% sodium hydroxide and stirred for 5 minutes. Subsequently, the inhibitor (the amount added is shown in Table 5) and the collector salicylhydroxyxamic acid were added sequentially, and stirred for 5 minutes each time. The flotation time was 5 minutes, and the stirring speed was fixed at 2300 r / min. After filtration and drying, the mass of the concentrate and tailings were accurately weighed, the grade was analyzed, and the yield and recovery rate were calculated. The results are shown in Table 5.

[0121] Table 5. Effects of inhibitor type and dosage on the flotation results of fine-grained cassiterite.

[0122] None 0 4.54 79.20 A 10 4.86 76.21 A 20 4.92 74.85 A 30 4.98 72.16 A 40 5.12 69.52 B 10 4.67 77.26 B 20 4.87 75.02 B 30 4.93 72.23 B 40 5.24 70.59 A + B 5+5 4.91 78.05 A + B 10+10 5.58 77.51 A + B 15+15 5.94 75.09 A + B 20+20 6.35 72.69 A + B 5+15 5.29 76.54 A + B 15+5 5.43 76.39

[0123] As shown in Table 5, for a certain inhibitor, the grade of cassiterite concentrate increases and the recovery rate decreases with increasing inhibitor dosage. When inhibitors A and B are mixed in a 1:1 ratio at the same dosage, the separation effect on fine-grained cassiterite is better than that of a single inhibitor, indicating that the combined inhibitors have a synergistic effect on the separation of fine-grained cassiterite.

[0124] The inventors also conducted the above-mentioned experiments on sulfonated starch and carboxylated starch prepared in other embodiments, and the results were basically the same. Due to space limitations, they will not be listed one by one.

[0125] Experimental Example 6

[0126] The inhibitors used in this experiment are the sulfonated starch (denoted as A) prepared in Example 2 and the carboxylated starch (denoted as B) prepared in Example 5.

[0127] This experiment demonstrates the flotation of fine cassiterite. The specific experimental procedure is as follows: A 0.75L XFGⅡ type hanging-cell flotation machine was used for the flotation of fine cassiterite, with a process of one roughing and two cleaning stages. The grade of the cassiterite ore was 0.5%, with a yield of 85% for the -74μm particle size and 50% for the -38μm particle size. A certain amount of cassiterite ore was prepared into a 40% slurry and placed in the flotation cell. The pH was adjusted to 8.0 using 5% sodium hydroxide for roughing, and the mixture was stirred for 5 minutes. Subsequently, the inhibitor (the amount added is shown in Table 6) and the collector salicylhydroxyxamic acid were added sequentially, and stirred for 5 minutes each time. The flotation time was 5 minutes, and the stirring speed was fixed at 2300 r / min. The flotation yielded a rougher concentrate and rougher tailings. The rougher concentrate was returned to the flotation cell for two cleaning stages to obtain the final concentrate. After filtration and drying, the yield and recovery rate were calculated, and the results are shown in Table 6.

[0128] Table 6. Effects of inhibitor type and dosage on the flotation results of fine-grained cassiterite.

[0129]

[0130] As shown in Table 6, for a certain inhibitor, as the inhibitor dosage increases, the grade of fine-grained cassiterite concentrate increases, while the recovery rate decreases. Under the same dosage conditions, when inhibitors A and B are mixed in a 1:1 ratio, the separation effect on fine-grained cassiterite is better than that of a single inhibitor, indicating that the combined inhibitors have a synergistic effect on the separation of fine-grained cassiterite.

[0131] The inventors also conducted the above-mentioned experiments on sulfonated starch and carboxylated starch prepared in other embodiments, and the results were basically the same. Due to space limitations, they will not be listed one by one.

[0132] Experimental Example 7

[0133] The inhibitors in this experiment were unsulfonated starch, i.e., corn starch (average molecular weight 120,000, denoted as A), and uncarboxylated starch, i.e., corn starch (average molecular weight 200,000, denoted as B).

[0134] This experimental example demonstrates the flotation of fine-grained ilmenite ore. The experimental procedure is as follows: An XFGⅡ type hanging-cell flotation machine with a flotation cell volume of 0.75L was used for the flotation of actual fine-grained ilmenite ore, following a roughing-cleaning process. The grade of the fine-grained ilmenite ore was 18%, with a yield of over 90% for the -74µm particle size and a yield of 40-50% for the -38µm particle size. 225g of actual ore (pulp concentration of 30%) was placed in the flotation cell, and the pH was adjusted to 5.0 with 5% sulfuric acid. The mixture was stirred for 5 minutes, followed by the sequential addition of inhibitors and collector sodium oleate, each stirred for 5 minutes. The total flotation time was 5 minutes, and the stirring speed was fixed at 2300 r / min. The flotation yielded a rougher concentrate and tailings. The rough concentrate was further refined by adding sulfuric acid to adjust the pH to 4-5, resulting in refined concentrate and refined tailings. The refined concentrate is the final concentrate. The grade was tested, and its yield and recovery were calculated. The results are shown in Table 7.

[0135] Table 7. Effects of inhibitor type and dosage on the flotation results of fine-grained ilmenite.

[0136]

[0137]

[0138] As shown in Table 7, for a certain inhibitor, due to its large molecular weight, the grade of fine-grained ilmenite concentrate increases with increasing inhibitor dosage, but the recovery rate decreases rapidly, indicating that the macromolecular inhibitor has a stronger inhibitory effect on ilmenite. The flotation effect of combined inhibitors on minerals shows that the combined inhibitors have an insignificant effect on the separation of fine-grained ilmenite.

[0139] Experimental Example 8

[0140] The inhibitors in this experiment were unsulfonated starch, i.e., corn starch (average molecular weight 120,000, denoted as A), and uncarboxylated starch, i.e., corn starch (average molecular weight 200,000, denoted as B).

[0141] This experiment demonstrates the flotation of fine cassiterite. The specific experimental procedure is as follows: A 0.75L XFGⅡ type hanging trough flotation machine was used for the flotation of fine cassiterite, with a process of one roughing and two cleaning stages. The grade of the cassiterite ore was 0.5%, with a yield of 85% for the -74µm particle size and 50% for the -38µm particle size. A certain amount of cassiterite ore was prepared into a 40% slurry and placed in the flotation cell. The pH was adjusted to 8.0 using 5% sodium hydroxide for roughing, and the mixture was stirred for 5 minutes. Subsequently, the inhibitor (the amount added is shown in Table 6) and the collector salicylhydroxyxamic acid were added sequentially, and stirred for 5 minutes each time. The flotation time was 5 minutes, and the stirring speed was fixed at 2300 r / min. The flotation yielded a rougher concentrate and rougher tailings. The rougher concentrate was returned to the flotation cell for two cleaning stages to obtain the final cassiterite concentrate. After filtration and drying, its yield and recovery rate were calculated.

[0142] The results were basically consistent with those of Example 7. This is because the inhibitor has a large molecular weight. As the amount of inhibitor increases, the grade of fine-grained cassiterite concentrate increases, but the recovery rate decreases rapidly, indicating that the macromolecular inhibitor has a strong inhibitory effect on both gangue minerals and target minerals. The flotation effect of the combined inhibitor on minerals shows that the combined inhibitor has no significant effect on the separation of fine-grained ilmenite.

[0143] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention, such as calcite, a gangue mineral, during tungsten ore beneficiation, should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a mineral processing inhibitor, characterized in that, The process includes preparing carboxylated starch and sulfonated starch separately, and then mixing the carboxylated starch and sulfonated starch to obtain the mineral processing inhibitor; wherein, according to the mass ratio, sulfonated starch: carboxylated starch = 1:0.3~3; The sulfonated starch is prepared by the following method: (1) Disperse natural starch in ethanol, activate it under ultrasonic treatment, and dry it to obtain activated starch; The ultrasonic power is 250~300W, and the ultrasonic time is 2~8min; (2) Mix ethanol and ammonium sulfate, then add concentrated sulfuric acid and the activated starch in sequence to carry out the reaction, adjust the pH value to 8.5~10.5, and obtain crude sulfonated starch product; The volume fraction of ethanol is ≥80%, and the volume-to-mass ratio of ethanol, ammonium sulfate, concentrated sulfuric acid and activated starch is 35.0~40.0mL:0.8~1.2g:24.0~28.0mL:1.5~2.5g. (3) The crude sulfonated starch product is placed in a dialysis bag with a molecular weight cutoff of 100~2000 Da and repeatedly dialyzed with ultrapure water to remove unreacted ethanol, sulfuric acid and ammonium sulfate. After freeze drying and grinding into powder, the sulfonated starch is obtained.

2. The method for preparing a mineral processing depressant according to claim 1, characterized in that, The carboxylated starch is prepared by the following method: (I) React natural starch and acetic acid solution at 70~90℃ for 2-10h to obtain solution A; (II) Hydrogen peroxide is slowly added dropwise to solution A, and the reaction is carried out at 60~90℃ for 1~5h. The pH is adjusted to neutral, and the solution is dried to obtain the carboxylated starch.

3. The method for preparing a mineral processing inhibitor according to claim 2, characterized in that, In step (I), the natural starch is corn starch, and the mass concentration of the acetic acid solution is 1-10%.

4. The method for preparing a mineral processing depressant according to claim 2, characterized in that, In step (I), the mass-to-volume ratio of natural starch to acetic acid solution is 1g:20~40mL.

5. The method for preparing a mineral processing depressant according to claim 2, characterized in that, In step (II), the volume ratio of hydrogen peroxide to acetic acid solution is 1 / 10 to 1 / 2.

6. The application of a mineral processing inhibitor prepared by the method according to any one of claims 1-5 in the flotation of calcium-magnesium gangue minerals.

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