Preparation of hydroxypropyl sulfonated sulfate lignin and its use as a calcium-containing gangue mineral inhibitor

Abstract

The application discloses preparation of hydroxypropyl sulfonated kraft lignin and application of the hydroxypropyl sulfonated kraft lignin as a calcium-containing gangue mineral inhibitor. The hydroxypropyl sulfonated kraft lignin is applied to flotation separation of scheelite and fluorite and calcite, and shows high selective inhibition to the calcium-containing gangue mineral, so that the flotation separation recovery rate of the scheelite can be improved. The hydroxypropyl sulfonated kraft lignin is easy to obtain, low in cost, biodegradable, less in environmental pollution, and favorable for popularization and use.

Description

TECHNICAL FIELD

[0001] The application relates to application of hydroxypropyl sulfonated kraft lignin as a calcium-containing gangue mineral inhibitor, in particular to application of hydroxypropyl sulfonated kraft lignin as a calcium-containing gangue mineral inhibitor in flotation separation of scheelite and fluorite and / or calcite, and belongs to the technical field of ore dressing. BACKGROUND

[0002] With long-term overexploitation of easily selected scheelite resources, the main development target of tungsten resources is gradually shifted to high-reserve but refractory scheelite resources. Although scheelite has large reserves, it has low grade and many associated minerals. The associated calcium-containing gangue minerals, calcite and fluorite, are the main factors causing the difficulty in scheelite flotation separation, so it is of great significance to study a green inhibitor for effectively separating scheelite and calcium-containing gangue minerals.

[0003] The conventional collector in scheelite flotation mainly includes sodium oleate, but it cannot effectively separate scheelite and calcium-containing gangue minerals. In industrial production, the most widely used inhibitor in tungsten ore flotation is mainly composed of water glass, sodium alginate and carboxymethyl cellulose. These inhibitors have a large dosage, limited effect and even cause serious water pollution. Lignin lignosulfonate has achieved wide application and active progress in the field of flotation separation of calcium-containing minerals; it not only avoids environmental pollution caused by inorganic inhibitors, but also effectively utilizes sulfite paper pulp waste liquid. However, due to random sulfonation in the pulping process, the molecular weight of commercial lignosulfonate is large, and the molecular weight distribution is wide. Kraft lignin sulfate is the product of the most common kraft pulping black liquor in China, and has the advantages of high purity, large quantity, low price and many active sites. Therefore, it has become a research hotspot to prepare anionic surfactants by chemical modification of kraft lignin sulfate. The functional group type, molecular weight distribution, viscosity, functional group spatial configuration and surface charge density all affect the adsorption mechanism and inhibition effect. Therefore, it is of great significance to prepare a new green inhibitor with both selectivity and inhibition capacity by structural design of industrial kraft lignin sulfate which is more widely available, for the separation of calcium-containing minerals. SUMMARY

[0004] In view of the defects in the prior art, the application aims to provide application of hydroxypropyl sulfonated kraft lignin as a calcium-containing gangue mineral inhibitor. The hydroxypropyl sulfonated modified kraft lignin can have more hydrophilic groups, sulfonic acid groups, high selective adsorption on the surfaces of fluorite and calcite and strong hydrophilic modification effect on the surfaces, high inhibition effect on flotation, and almost no effect on the adsorption of sodium oleate on the surface of scheelite, so that the separation effect of scheelite and calcium-containing gangue minerals can be improved. The hydroxypropyl sulfonated kraft lignin is widely available, low in cost, biodegradable, green and environmentally friendly, low in dosage, high in effect, and conducive to popularization and application.

[0005] In order to achieve the above technical purposes, the application provides an application of hydroxypropyl sulfonated kraft lignin as a calcium-containing gangue mineral inhibitor.

[0006] The technical scheme of the application first uses hydroxypropyl sulfonated kraft lignin as a calcium-containing gangue mineral inhibitor, which is mainly based on the fact that the active groups of hydroxypropyl sulfonated kraft lignin not only have high selective adsorption activity on calcium-containing gangue minerals, but also can reduce the adsorption of a flotation collector on the surface of the calcium-containing gangue minerals, and the hydroxypropyl sulfonated kraft lignin has abundant hydrophilic groups, which can be selectively adsorbed on the surface of the calcium-containing gangue minerals to achieve hydrophilic modification, thereby inhibiting the flotation of the calcium-containing gangue minerals.

[0007] As a preferred scheme, the calcium-containing gangue minerals include calcite and / or fluorite. The hydroxypropyl sulfonated kraft lignin has strong adsorption selectivity on the surface of calcite and fluorite, and thus has a particularly significant inhibiting effect on calcite and fluorite.

[0008] As a preferred scheme, the hydroxypropyl sulfonated kraft lignin is used as a calcium-containing gangue mineral inhibitor for the flotation separation of scheelite and calcium-containing gangue minerals. In the flotation process of scheelite, the hydroxypropyl sulfonated kraft lignin has almost no adsorption on the surface of scheelite, and mainly selectively acts on the calcium-containing gangue minerals to achieve selective hydrophilic modification on the surface of the calcium-containing gangue minerals, thereby facilitating the flotation separation of scheelite and the calcium-containing gangue minerals.

[0009] As a preferred scheme, sodium oleate is used as a scheelite collector and the hydroxypropyl sulfonated kraft lignin is used as a calcium-containing gangue mineral inhibitor in the flotation separation process. In the flotation separation process of scheelite, the adsorption capacity of sodium oleate on the surface of scheelite is much greater than that of the hydroxypropyl sulfonated kraft lignin, so that the addition of the hydroxypropyl sulfonated kraft lignin does not affect the capture of sodium oleate on the calcium-containing gangue minerals, and the adsorption of the hydroxypropyl sulfonated kraft lignin on the surface of calcite, fluorite and other calcium-containing gangue minerals is much stronger than that of sodium oleate, thereby avoiding the adsorption of sodium oleate on the surface of the calcium-containing gangue minerals. Therefore, the two can be used in combination to achieve efficient flotation separation of scheelite and the calcium-containing gangue minerals.

[0010] As a preferred scheme, the amount of sodium oleate in the ore slurry system is 90-120 mg / L. As a preferred scheme, the amount of hydroxypropyl sulfonated kraft lignin in the ore slurry system is 40-60 mg / L. The hydroxypropyl sulfonated kraft lignin has the characteristics of low dosage and significant inhibiting effect, and thus can reduce the usage amount of the hydroxypropyl sulfonated kraft lignin as an inhibitor. If the amount of the hydroxypropyl sulfonated kraft lignin is too low, the effect of inhibiting the calcium-containing gangue minerals cannot be achieved, and if the amount of the hydroxypropyl sulfonated kraft lignin is too high, the adsorption of sodium oleate on the surface of scheelite will be affected, thereby reducing the flotation separation effect.

[0011] As a preferred scheme, the pH of the ore pulp system in the process of the flotation separation is 9-12. Under the preferred pH condition, the flotation separation of scheelite and calcium-containing gangue minerals is more favorable.

[0012] As a preferred scheme, the content of the sulfonic acid group of the hydroxypropyl sulfonated kraft lignin is 1-5 mmol / g. More preferably, it is 1-3 mmol / g.

[0013] As a preferred scheme, the hydroxypropyl sulfonated kraft lignin is obtained by sulfonation of kraft lignin and sodium 3-chloro-2-hydroxypropane sulfonate.

[0014] As a more preferred scheme, after the kraft lignin aqueous solution is adjusted to a pH of 9-10.5, the sodium 3-chloro-2-hydroxypropane sulfonate aqueous solution is added dropwise, and the temperature is raised to 80-90°C for 2-4h to obtain the hydroxypropyl sulfonated kraft lignin.

[0015] The preparation method of the hydroxypropyl sulfonated kraft lignin of the present application is as follows:

[0016] 1) The aqueous solution containing sodium bisulfite and sodium hydroxide (the concentration of sodium bisulfite is 15-25 wt.%) is subjected to ring-opening reaction with 3-chloro-1,2-epoxypropane to obtain sodium 3-chloro-2-hydroxypropane sulfonate aqueous solution, wherein the mass ratio of sodium bisulfite, sodium hydroxide and 3-chloro-1,2-epoxypropane is 80-100:1:70-80, and the ring-opening reaction process is as follows: 3-chloro-1,2-epoxypropane is slowly added dropwise at room temperature, and after the addition is completed, the temperature is first raised to 30-45°C for 2-3h, and then the temperature is raised to 80-90°C for 0.5-1.5h. Meanwhile, the sodium 3-chloro-2-hydroxypropane sulfonate can also be directly replaced by a commercially available product.

[0017] 2) The kraft lignin is prepared into a 3-5 wt.% aqueous solution, and after the pH is adjusted to 9-10.5, the above-mentioned sodium 3-chloro-2-hydroxypropane sulfonate aqueous solution is added dropwise (the mass ratio of kraft lignin and sodium 3-chloro-2-hydroxypropane sulfonate aqueous solution is 1-2:2-4), and the temperature is raised to 80-90°C for 2-4h to obtain the hydroxypropyl sulfonated kraft lignin.

[0018] The hydroxypropyl sulfonated kraft lignin provided by the present application is used as a calcium-containing gangue mineral inhibitor in the method for scheelite flotation separation, which comprises the following steps:

[0019] 1) The raw ore (scheelite, fluorite and calcite) is mechanically ground to below 200 mesh, and the ore pulp concentration is adjusted to about 4.7% in the aqueous solution;

[0020] 2) The pH of the ore pulp is adjusted to 9-12 using sodium hydroxide;

[0021] 3) adding hydroxypropyl sulfonated sulfate lignin inhibitor to the ore pulp, stirring, adding sodium oleate collector, and obtaining scheelite concentrate through flotation scraping foam (3 min).

[0022] Compared with the prior art, the technical scheme of the present application has the beneficial technical effects:

[0023] The present application first uses hydroxypropyl sulfonated sulfate lignin as a calcium-containing gangue mineral inhibitor. The hydroxypropyl sulfonated sulfate lignin not only has high selective adsorption activity on calcium-containing gangue minerals, but also can reduce the adsorption of the flotation collector on the surface of the calcium-containing gangue minerals. In addition, the hydroxypropyl sulfonated sulfate lignin has abundant hydrophilic groups, which can be selectively adsorbed on the surface of the calcium-containing gangue minerals to achieve surface hydrophilic modification and improve the dispersibility of the calcium-containing gangue minerals in the ore pulp system, thereby inhibiting the flotation of the calcium-containing gangue minerals. In particular, the hydroxypropyl sulfonated sulfate lignin is used in the flotation process of scheelite. The hydroxypropyl sulfonated sulfate lignin has high selective adsorption and strong surface hydrophilic modification effect on fluorite and / or calcite, and has high inhibition effect on the flotation of fluorite and / or calcite, while having little effect on the adsorption of sodium oleate on the surface of scheelite, thereby improving the separation effect of scheelite and calcium-containing gangue minerals.

[0024] The hydroxypropyl sulfonated sulfate lignin used as a calcium-containing gangue mineral inhibitor in the present application has a wide source, is easy to obtain, has low cost, is biodegradable, is green and environmentally friendly, has low dosage, and has remarkable effect, and is conducive to popularization and application. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A flowchart of mineral flotation.

[0026] Figure 2 The influence of hydroxypropyl sulfonated sulfate lignin on the flotation recovery rate of scheelite, fluorite and calcite.

[0027] Figure 3 The Zeta potential change of the single mineral before and after the action of hydroxypropyl sulfonated sulfate lignin.

[0028] Figure 4 The XPS graph of the single mineral before and after the action of hydroxypropyl sulfonated sulfate lignin on scheelite. DETAILED DESCRIPTION

[0029] The technical scheme of the present application will be further described below in combination with specific embodiments of the present application. It should be noted that the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. These embodiments are only for better understanding of the present application, but not for limiting the scope of the present application.

[0030] Preparation method of the hydroxypropyl sulfonated sulfate lignin inhibitor:

[0031] 20g of sodium bisulfite was dissolved in 70mL of water solution in a four-necked flask, 0.2g of sodium hydroxide was added, 16g of 3-chloro-1,2-epoxypropane was slowly added dropwise under the condition of 25℃ and 600rpm stirring. Then the temperature was increased to 45℃, the reaction was carried out for 2h, and then the temperature was increased to 90℃, the reaction was carried out for 1h, and then 3-chloro-2-hydroxypropane sulfonic acid sodium water solution was obtained.

[0032] 2.0g of sulfite lignin was dissolved in 50mL of water solution in a three-necked flask, 0.2g of NaOH was added to adjust the pH value; then 3.5g of 3-chloro-2-hydroxypropane sulfonic acid sodium water solution was added dropwise, the temperature was increased to 90℃, and the reaction was carried out for 2h; after the solution was cooled to room temperature, 1000Da dialysis bag was used for dialysis to remove inorganic salts, and finally it was dried in a 60℃ oven to obtain hydroxypropyl sulfonated sulfite lignin inhibitor.

[0033] As shown in Table 1, the molecular weight and sulfonic acid group content of sulfite lignin and hydroxypropyl sulfonated lignin. After modification, the weight average molecular weight M w of KL and HS KL is 4920Da and 5175Da respectively, and the content of sulfonic acid group of HS KL is 2.08mmol / g, which indicates that the hydroxypropyl sulfonation reaction of 3-chloro-2-hydroxypropane sulfonic acid sodium makes KL access sulfonic acid group.

[0034] Table 1

[0035]

[0036] Example 1

[0037] As Figure 1 shown, 2g of scheelite single mineral was weighed in the test, which was added into a flotation tank with a volume of 40mL and stirred for 1min, 0.2g of sodium hydroxide was added as pH regulator, and the pH value was 10.5, and the stirring was carried out for 3min; a certain amount of inhibitor was added, and the stirring was carried out for 3min; 90mg / L of sodium oleate water solution was added, and the stirring was carried out for 3min. Finally, the bubble scraping operation was carried out, and the bubble scraping time was 3min. The foam product was dried, weighed, and the recovery rate was calculated. The same test was carried out on fluorite and calcite single minerals.

[0038] As Figure 2The effect of the amount of hydroxypropyl sulfonated kraft lignin inhibitor (HSKL) on the recovery rate of single mineral flotation was shown in the table. The amount of sodium oleate collector was 90 mg / L, and the pH was 10.5. With the increase of the amount of HSKL, the recovery rates of both calcite and fluorite single minerals decreased, but the recovery rate of scheelite remained at about 90%. When the concentration of HSKL was 40 mg / L, the recovery rates of scheelite, calcite and fluorite were 92.10%, 5.30% and 10.01%, respectively. Therefore, the hydroxypropyl sulfonated kraft lignin inhibitor (HSKL) can effectively separate scheelite from calcite and fluorite when used in a small amount.

[0039] Example 2

[0040] To further evaluate the effect of the HSKL inhibitor in Example 1 on the separation of scheelite, calcite and fluorite, artificial mixed minerals were used to evaluate the separation effect of the three minerals. In the test, scheelite:fluorite was weighed in a mass ratio of 1:1, and the total mass was 2g. The scheelite and fluorite were added to a flotation tank with a volume of 40 mL and stirred for 1 min. Sodium hydroxide was added as a pH adjuster to adjust the pH to 10.5, and stirred for 3 min. The inhibitor was added at a concentration of 70 mg / L, and stirred for 3 min. Sodium oleate aqueous solution was added at a concentration of 90 mg / L, and stirred for 3 min. Finally, the froth was scraped for 3 min. The froth product was dried, weighed, and the recovery rate was calculated. The same test was conducted on scheelite:calcite in a mass ratio of 1:1 and scheelite:calcite:fluorite in a mass ratio of 1:1:1.

[0041] The results of the artificial mixed mineral test are shown in Table 2. When the mixed minerals were treated with HSKL, the grade of WO3 in the concentrate was improved. When scheelite and fluorite were mixed in a 1:1 ratio, the grade of WO3 in the concentrate mixture was improved by 15.86%. When scheelite and calcite were mixed in a 1:1 ratio, the grade of WO3 in the concentrate mixture was increased by 24.01%. When scheelite:calcite:fluorite was mixed in a 1:1:1 ratio, the grade of WO3 in the concentrate mixture was improved by 22.82%. The recovery rate of the artificial mixed minerals was as low as 71.35%. This result shows that the use of HSKL can achieve good separation of scheelite, calcite and fluorite, and can be used as a potential inhibitor for the separation of scheelite and calcium-containing gangue minerals.

[0042] Table 2

[0043]

[0044] Example 3

[0045] Surface charge is crucial in mineral flotation because it is closely related to the adsorption of reagents on the mineral surface. Therefore, the adsorption behavior of HSKL on the mineral surface was investigated by studying the Zeta potential of these three minerals under different pH conditions. Figure 3 As shown. The Zeta potential in aqueous scheelite solution is within the pH range of 6–12 due to the preferential dissociation of calcium ions, and an excess of WO4 is present on the scheelite surface. 2－ Scheelite has a negatively charged surface. The zeta potential of scheelite treated with HSKL showed little change, indicating that HSKL adsorbed only a small amount on the scheelite surface. However, before and after treatment with the HSKL solution, the zeta potentials of calcite and fluorite decreased sharply with increasing pH (from 6 to 12). At around pH 10.5, the zeta potentials of calcite and fluorite decreased by approximately 21.27 eV and 19.10 eV, respectively. This indicates that HSKL strongly adsorbed on the surfaces of calcite and fluorite, leading to a reduced recovery rate of these two minerals.

[0046] Result detection:

[0047] like Figure 4 The image shows XPS narrow scan spectra of Ca 2p on the surfaces of three single minerals before and after adsorption in HSKL solution. The binding energies of Ca 2p 3 / 2 and Ca 2p 1 / 2 on the scheelite surface are 347.02 eV and 350.56 eV, respectively. After adsorption in HSKL solution, the binding energies of Ca 2p 3 / 2 and Ca 2p 1 / 2 on the scheelite surface shifted by -0.05 eV and -0.08 eV, respectively. These small shifts in the Ca 2p peaks on the scheelite surface after adsorption in HSKL solution are within the range of instrument error, suggesting that the adsorption of HSKL on the scheelite surface is weak.

[0048] The binding energies of Ca 2p 3 / 2 and Ca 2p 1 / 2 on the calcite surface are 347.32 eV and 350.85 eV, respectively. After calcite adsorbs in HSKL solution, the binding energies of Ca 2p 3 / 2 and Ca 2p 1 / 2 on the calcite surface shift by -0.23 eV and -0.24 eV, respectively. The peak at 348.28 eV corresponds to Ca 2p 3 / 2 on the fluorite surface, and the peak at 351.83 eV corresponds to Ca 2p 1 / 2 on the fluorite surface. After adsorption in HSKL solution, the binding energy of Ca 2p 3 / 2 on the fluorite surface shifts by -0.22 eV to 348.06 eV, and the binding energy of Ca 2p 1 / 2 shifts by -0.21 eV to 351.62 eV. Following adsorption in HSKL solution, HSKL adsorbs onto the surfaces of both fluorite and calcite.

[0049] The above examples are only for better explaining the principles and practical applications of the present application, so as to make the relevant technical field personnel better understand and utilize the present application, and do not limit the patent scope of the present application, and any equivalent transformation made by using the content of the present application is within the patent protection scope of the present application.

Claims

1. Use of hydroxypropyl sulfonated sulfate lignin, characterized in that: The hydroxypropyl sulfonated sulfate lignin is applied as a calcium-containing gangue mineral inhibitor. The content of sulfonic acid groups of the hydroxypropyl sulfonated sulfate lignin is 1-5 mmol / g. The hydroxypropyl sulfonated sulfate lignin is obtained by sulfonation reaction of sulfate lignin and sodium 3-chloro-2-hydroxypropyl sulfonate.

2. Use of a hydroxypropyl sulfonated sulfate lignin according to claim 1, characterized in that: The calcium-containing gangue mineral includes calcite and / or fluorite.

3. Use of a hydroxypropyl sulfonated sulfate lignin according to claim 1 or 2, characterized in that: The hydroxypropyl sulfonated sulfate lignin is applied as a calcium-containing gangue mineral inhibitor for flotation separation of scheelite and calcium-containing gangue mineral.

4. Use of a hydroxypropyl sulfonated sulfate lignin according to claim 3, characterized in that: In the process of the flotation separation, sodium oleate is used as a scheelite collector and the hydroxypropyl sulfonated sulfate lignin is used as a calcium-containing gangue mineral inhibitor.

5. Use of a hydroxypropyl sulfonated sulfate lignin according to claim 4, characterized in that: The amount of the sodium oleate in the ore pulp system is 90-120 mg / L. The amount of the hydroxypropyl sulfonated sulfate lignin in the ore pulp system is 40 mg / L-60 mg / L.

6. Use of a hydroxypropyl sulfonated sulfate lignin according to claim 4, characterized in that: In the process of the flotation separation, the pH of the ore pulp system is 9-12.

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