Collectors and flotation methods for separating extremely difficult-to-separate scheelite containing soluble gangue

Abstract

The present invention discloses a collector and a flotation method for separating extremely refractory scheelite containing soluble gangue, relating to a green collector and a beneficiation method for flotation of extremely refractory scheelite containing soluble gangue (such as gypsum), which includes three kinds of biosurfactants with amide groups and carboxyl groups used as collectors to conduct flotation separation on scheelite containing soluble gangue (such as gypsum). The present invention adopts the method of single mineral flotation. The three kinds of biosurfactants have good collecting effects on the flotation of scheelite. When the concentration is 1×10<supgt;‑4< / supgt;mol / L, the recovery rate of single mineral in a high-calcium environment can reach more than 95%, and at the same time, it has good collecting effects within a wide pH range. The three kinds of biosurfactants described in the present invention have the characteristics of being green, safe, non-toxic, high selectivity, high recovery rate, resistant to calcium ion interference, and wide pH adaptation range, overcoming the inhibitory effect of a large amount of calcium ions in the pulp solution on the flotation of scheelite and improving the flotation recovery rate of extremely refractory scheelite in a high-calcium environment. The collector described in the present invention can be naturally degraded at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of flotation reagents, and particularly relates to a green collector and a flotation method for separating extremely difficult-to-separate scheelite containing soluble gangue. Background Art

[0002] Tungsten is an important key strategic metal in China. Tungsten has the advantages of high melting point, high hardness, stable chemical properties, good electrical conductivity, high magnetic resistance and corrosion resistance. It is hard and brittle, and can be made into very fine filaments and special alloy steels (tungsten filaments, ferrotungsten, tungsten steel), and is widely used in many fields such as machinery, national defense, aerospace, electric power, metallurgy, and chemical industry. As an advantageous strategic mineral resource in China, the secure supply of tungsten is of great significance to the national economy, especially national defense security.

[0003] Scheelite (calcium tungstate) as a kind of tungsten ore has a large reserve in China (about 70% of the national tungsten reserve). Coupled with the increasing depletion of wolframite (ferberite) resources, the flotation recovery of scheelite is of great significance for the utilization of tungsten resources. Scheelite usually coexists with calcium-containing gangue minerals (such as calcite, gypsum, dolomite) because they have similar physical and chemical properties and the same Ca 2+ central site exposed on the mineral surface. Therefore, it is very difficult to separate the two by flotation. Oleic acid is widely used in the flotation of various metal minerals due to its unique collecting performance and is a commonly used collector in the flotation of scheelite. Oleate ions can react with metal ions other than alkali metals to form metal salt precipitates, and then adsorb on the surface of scheelite and combine with the Ca 2+ central site to achieve the flotation separation of scheelite. With the rapid development of the economy, the demand for tungsten metal is huge. The high-quality scheelite resources that are traditionally easy to float and separate and have high valuable metal grades are gradually consumed, and the sustainable supply of tungsten metal faces challenges. The flotation of complex and difficult-to-separate, low-grade refractory scheelite has become a major problem faced by the development of tungsten resources and urgently needs scientific and technological research to solve.

[0004] Scheelite containing a large amount of soluble calcium minerals (such as gypsum) is a typical refractory tungsten ore. A large amount of calcium ions are dissolved from the ore in the pulp, seriously deteriorating the selective separation of valuable minerals (scheelite) from calcium-containing gangue (calcite, dolomite, etc.). On the one hand, the traditional collector sodium oleate reacts with the calcium ions dissolved from the ore in the pulp solution, resulting in the consumption of the collector and reducing the separation selectivity. On the other hand, at low pH, the flotability of the traditional collector rapidly decreases, which is related to the fact that the anionic collector fails to be deprotonated at low acidity and cannot chemically interact with the calcium sites on the surface of scheelite. At the same time, traditional collectors such as oleic acid and hydroxamic acid cannot be naturally degraded and cannot meet the high requirements of green mine and ecological environmental protection construction. Patent No. CN108906331B discloses a hydrocarbon amide-bis-hydroxamic acid type scheelite collector with good selectivity, but the preparation of this reagent is complex, the cost is high, it cannot be degraded and pollutes the environment, and it is difficult to be popularized and applied industrially. Patent No. CN111346737A discloses a n-tetradecyl isopropanolamine collector for flotation of scheelite. This type of collector has good selectivity. However, it mainly relies on electrostatic adsorption force, resulting in a low collecting ability of the collector. This paper believes that introducing an amide group into the molecular structure of the collector can avoid the interference of calcium ions on flotation. Based on this, a new type of collector with good separation index, which can overcome the interference of complex calcium ion environment and is green and degradable, is proposed and applied to the flotation of refractory scheelite.

[0005] Biosurfactants with amide groups and carboxyl groups have attracted more and more attention due to their excellent surface properties. This type of reagent has excellent foaming properties, strong collecting ability for ores, high stability to changes in acid-base environment, and can be naturally degraded and is environmentally friendly. It is a potential excellent collector. The inventor innovatively found that the three compounds shown in Formula I - Formula III belong to amino acid-type anionic surfactants. Compared with sodium oleate, the three compounds shown in Formula I - Formula III all contain amide groups. Under high calcium ion conditions, the amide group may 2+ carry out a cooperative adsorption reaction with the Ca Summary of the Invention

[0006] Aiming at the problems that the separation of scheelite containing soluble gangue (such as gypsum) is very difficult and the collector is difficult to degrade and pollute the environment, the present invention conducts flotation experiments on high-calcium extremely refractory scheelite by using a new type of green biological collector, so as to achieve the effects of high recovery rate, reducing the interference of calcium and magnesium ions in the solution, maintaining strong flotation performance in acid-base environments, and being green and environmentally friendly. To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A collector for separating extremely difficult-to-separate scheelite containing soluble gangue, characterized in that the flotation collector is one of the three compounds shown in Formula I - Formula III, the single-molecule structure of the collector contains multiple functional groups, the molecular structure of the collector has a carboxyl group and an amide group, and the chemical formulas of the three compounds are as follows:

[0008] Formula I:

[0009]

[0010] Formula II:

[0011]

[0012] Formula III:

[0013]

[0014] A flotation method using a collector for separating extremely difficult-to-separate scheelite containing soluble gangue, characterized by including the following steps:

[0015] (1) Mix 3 g of the scheelite sample weighed with 0.3 g of gypsum and add deionized water to a 60 mL flotation cell, stir for 1 min first, adjust the pH to 3 - 11, and then stir for 2 min.

[0016] (2) Add a collector of one of Formula I - Formula III to the pulp obtained in step (1), stir for 2 min, wherein the dosage of the collector is 1 - 30 (×10 -5 mol / L), and then carry out flotation for 5 min.

[0017] Further, the pulp - adjusting rotation speed is 1700 r / min.

[0018] Further, the particle size of the selected ore sample is 200 - 400 mesh.

[0019] Further, the flotation ventilation volume is 0.1 NL / min.

[0020] Further, after the flotation is completed, the foam flotation products, namely the concentrate and the tailings, are filtered, dried, weighed respectively, and the recovery rate is calculated, wherein the drying temperature is 60 °C and the drying time is 6 h.

[0021] In the above - mentioned scheme, the pH is adjusted with NaOH and HCl solutions. The present invention has no special requirements for the pH adjuster.

[0022] Compared with the traditional flotation of scheelite with sodium oleate, the advantages of the present invention are as follows: it can overcome the interference of a large amount of calcium ions in the pulp on flotation, and can obtain good flotation results with a very small dosage of collector; and the process is relatively simple, without the addition of foaming agent, and the collector still has good flotation effect in a wide range of pulp pH values, and is more adaptable to a more complex environment. The collector in the present invention can be naturally degraded, has little disturbance to the mine environment, and is beneficial to ecological environmental protection construction. In the scheelite separation experiment and practical application, the three collectors of the present invention with the chemical formulas I - III have strong collecting ability for scheelite, greatly improving the flotation effect compared with the collectors in the prior art. And surprisingly, it is found that when there are a large amount of calcium ions in the pulp, overcoming the defects of the collectors in the prior art, the collectors in the present invention still maintain good floatability for scheelite and obtain ideal flotation results. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the process flow chart of flotation of scheelite in the experiment;

[0024] Figure 2 It is the collecting performance diagram of four collectors in a high - calcium environment;

[0025] Figure 3 It is the recovery rate diagram of three collectors at different pH values;

[0026] Figure 4 It is the collecting mechanism of three collectors;

[0027] Figure 5 It is the flotation flow chart of extremely difficult - to - separate actual scheelite ore. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0029] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "vertical", "upper", "lower", "horizontal", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, "first", "second", "third", "fourth" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0030] In the description of the present invention, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "install", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be a direct connection or a connection through an intermediate medium. It can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] Example 1

[0032] As Figures 1-4 shown, the present invention relates to a collector for separating extremely difficult-to-select scheelite containing soluble gangue. The flotation collector is one of the three compounds shown in Formula I - Formula III, and the chemical formulas of the three compounds are as follows:

[0033] Formula I:

[0034]

[0035] Formula II:

[0036]

[0037] Formula III:

[0038]

[0039] In this implementation scheme, single-mineral flotation experiments were carried out using scheelite. The particle size of the flotation ore sample was +37 - -74 μm (that is, the sample particle size was greater than 37 μm and less than 74 μm).

[0040] The present invention also relates to a method for flotation of scheelite using the collector, including the following steps:

[0041] (1) Weigh 3 g of scheelite and 0.3 g of gypsum, mix the two in a 60 mL flotation cell, add deionized water according to the dosage of the collector, and finally mix to ensure that the volume of the solution is 60 mL, and stir for 1 min;

[0042] (2) Add a collector of one of Formula I - Formula III to the pulp solution obtained in step (1), stir for 2 min, and then carry out flotation. The flotation time is 5 min.

[0043] The flotation temperature is 25 °C.

[0044] The pulp adjusting speed is 1700 r / min.

[0045] The selected ore sample particle size is 200 - 400 mesh.

[0046] The flotation aeration rate is 0.1 NL / min.

[0047] After the flotation is completed, the froth concentrate is separated from the tailings in the cell. After filtration, drying, weighing, the recovery rate of flotation is calculated. The drying temperature is 60 °C and the drying time is 6 h.

[0048] In Figure 2 the collectors of Chemical Formula I - III are replaced by English letters as follows: SCG, SMG, LS. It can be seen from the figure that the collecting effect of the biosurfactant is significantly better than that of sodium oleate. Among them, the collecting effects of SCG and LS are the strongest. When the concentration reaches 1×10 -4 mol / L, the three reagents reach a very high recovery rate. When the collector concentration reaches 5×10 -5 mol / L, the efficiency of the three collectors for recovering scheelite is close to or exceeds 90%. Obviously, compared with the traditional sodium oleate, the collecting effects of the three reagents are significantly higher than that of sodium oleate. Moreover, in terms of the adaptability to the acid-base environment, the acid and alkali resistance shown by the three reagents is also significantly stronger than that of sodium oleate.

[0049] Example 2

[0050] On the basis of the operation steps of Example 1, control the concentrations of the three different collectors to be 1×10 -4 mol / L. Between Step (1) and Step (2), adjust the pulp pH to be between 3 and 11, and the flotation recovery rates of scheelite containing gypsum at different pH values are as Figure 2 shown. Under the condition of containing gypsum, the changes in the recovery rate of scheelite under different collector dosages are shown in Table 1.

[0051] Table 1 Changes in the recovery rate of scheelite containing gypsum with the collector dosage

[0052]

[0053] From Figure 3 it can be seen that the collecting effects of the three collectors SCG, SMG, and LS are poor in a strong acid environment, but their collecting effects are not greatly affected in other environments. Compared with sodium oleate, their collecting ability is much higher. The three biosurfactants show strong adaptability to the change of pulp solution pH. When containing gypsum, the changes in the recovery rate of scheelite with the pH value of different pulps are shown in Table 2.

[0054] Table 2 Changes in the recovery rate of scheelite containing gypsum with the pH dosage

[0055]

[0056] Figure 4There are three collector adsorption mechanisms. Compared with NaOl, amide groups are contained in SMG, SCG, and LS. Under high calcium ion conditions, the amide groups can interact with the calcium sites on the surface of scheelite, improving the calcium ion tolerance of the collector. In a pulp environment with high calcium ions, the inhibition of scheelite is not weaker than that when sodium oleate is used as the collector.

[0057] Under the condition of the presence of soluble calcium minerals such as gypsum, the results of flotation of scheelite using the three compounds SCG, SMG, and LS shown in Formula I - Formula III of the present invention are as shown in Table 1 and Figure 2 。Table 1 shows that the three compounds SCG, SMG, and LS shown in Formula I - Formula III have stronger collecting abilities compared with sodium oleate. When the dosage of these three collectors is in the range of 1×10 -5 mol / L to 1×10 - 4 mol / L, the flotation recovery rate rapidly increases from about 25% to more than 95% (SMG: 95.38%; SCG: 97.96%; LS: 98.34%). When sodium oleate is used, the process of increasing the flotation recovery rate is slower. When the dosage of sodium oleate is 1×10 -4 mol / L, the flotation recovery rate is 77.66%. After that, as the dosage of the reagent continues to increase, the flotation recovery rates of LS, SCG, and SMG tend to level off. When the dosage of the collector is 3×10 -4 mol / L, the flotation recovery rates of SMG, SCG, and LS reach the maximum values, which are 97.03%, 98.11%, and 99.41% respectively.

[0058] Select the collector dosage of 1×10 -4 mol / L to study the effect of pulp pH on flotation. The results are shown in Table 2. In the presence of gypsum, the flotation recovery rates of LS, SCG, and SMG show a trend of first increasing and then leveling off with the change of pH. When pH = 3, sodium oleate has almost no collecting ability for scheelite, while LS, SCG, and SMG can still recover a small amount of scheelite. Especially for LS, the flotation recovery rate can reach about 40%, which shows the strong acid resistance of the amide - carboxyl biosurfactant. After that, as pH increases, the flotation recovery rates of LS, SCG, and SMG gradually reach about 95%. The most noteworthy is the flotation ability of the collector in the alkaline condition in the presence of gypsum. When pH is in the range of 9 - 10, the flotation recovery rates of LS, SCG, and SMG all reach more than 90%. When pH = 11, the recovery rates of LS and SMG are maintained at about 90%, and the recovery rate of SCG drops to 75.56%. At this time, the flotation recovery rate of NaOl is only 19.29%.

[0059] The results of the flotation experiments showed that the presence of gypsum deteriorated the flotation of scheelite, leading to a sharp decline in the collecting ability of NaOl under alkaline conditions. The three novel biosurfactants used had good calcium tolerance. In the pH range of 9 - 10, even when the pulp contained gypsum, the flotation recovery rate of scheelite could reach over 90%, which might be attributed to the high activity of the surfactant containing amide - carboxyl groups. When there was no amide group, oleic acid with only one carboxyl group easily reacted with calcium ions in the solution and was precipitated, reducing the adsorption effect and selectivity of the collector. When both amide group and carboxyl group were present in the molecular structure, the amide group might hinder the precipitation reaction between calcium ions and carboxyl group in the solution. At the same time, the co - existence of amide group and carboxyl group made the surfactant an amphoteric surfactant, which had high surface activity at both low and high pH conditions and maintained the adsorption characteristics for scheelite. The Ca on the cleavage plane of scheelite 2+ The special concave - convex structure was also beneficial to the directional adsorption of the three biosurfactants containing amide groups on the surface of scheelite.

[0060] Example 3

[0061] The low - grade, complex and refractory scheelite in this example was the tailings of a molybdenite concentrator, with huge tungsten reserves and great development value. The low - grade ore in this example was seriously weathered. The tungsten trioxide in the ore was 0.13%. The main gangue minerals were gypsum (3.5%), calcite (9.1%), and dolomite (23.5%). The gangue minerals seriously deteriorated the separation effect. The existing collectors and processes could not solve the separation of this type of ore, and the ore had no separability. The precious tungsten resources were in an undeveloped state.

[0062] This example relates to a collector and a flotation method for separating extremely refractory scheelite containing soluble gangue. The method specifically includes the following steps.

[0063] In this example, the particle size of grinding - 200 mesh was 78.761%;

[0064] This example adopted a direct flotation process without desliming. Figure 5 This was the process adopted in this example;

[0065] Sodium carbonate was used as the regulator with a dosage of 1000 g / t, and water glass was used as the inhibitor with a dosage of 3000 g / t;

[0066] The dosage of the collector was 200 g / t;

[0067] Adopt Figure 5 the flotation process, the rotational speed of the flotation machine was 1900 r / min. After one - stage normal - temperature roughing, scheelite concentrate was obtained.

[0068] In this embodiment, the three biosurfactants are used as collectors, and the recovery rate of one rough selection reaches 60.868%, and the tungsten grade is increased to 0.225%. Under the same conditions, when sodium oleate is used as a collector, the flotation recovery rate of scheelite is only 39.086%.

[0069] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0070] The above-described embodiments only express the implementation manners of the present invention, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

1. A method for flotation of scheelite using a collector, characterized in that, The collector is a collector used for separating extremely difficult-to-separate scheelite containing soluble gangue. The collector is one of the two compounds shown in Formula I - Formula II. The single-molecule structure of the collector contains multiple functional groups. The molecular structure of the collector has a carboxyl group and an amide group. The chemical formulas of the two compounds are as follows: Formula I: Formula II: The method includes the following steps: (1) Mix 3 g of the scheelite sample weighed with 0.3 g of gypsum and add deionized water to a 60 mL flotation cell, stir for 1 min first, adjust the pH to 9 - 10, and then stir for 2 min; (2) Add a collector of one of Formula I - Formula II to the pulp obtained in step (1) and stir for 2 min. The dosage of the collector is 5×10 -5 mol / L - 10×10 -5 mol / L, then carry out flotation. The flotation time is 5 min, the pulp - adjusting rotation speed is 1700 r / min, the particle size of the selected ore sample is 200 - 400 mesh, the flotation ventilation volume is 0.1 NL / min. After flotation, filter, dry and weigh the foam flotation products, i.e., concentrate and tailings respectively, and calculate the recovery rate. The drying temperature is 60 °C and the drying time is 6 h.

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