USE OF 2-CYANO-N-(SUBSTITUTED CARBAMOYL)ACETAMIDE COMPOUND IN FLOTATION OF CALCIUM-BEARING MINERALS

Abstract

A collector 2-cyano-N-(substituted carbamoyl)acetamide compound in flotation of calcium-bearing minerals and a highly selective flotation reagent for the calcium-bearing minerals are provided. The highly selective flotation reagent includes the 2-cyano-N-(substituted carbamoyl)acetamide compound and an auxiliary collector. The 2-cyano-N-(substituted carbamoyl)acetamide compound has an excellent effect on flotation separation of the calcium-bearing minerals and a foaming performance. Dosage is further reduced and a flotation performance is improved by compounding the compound with the auxiliary collector. The flotation reagent can preferably separate fluorite from calcite by flotation, efficiently separates the fluorite and the calcite from scheelite under neutral condition (pH is about 7), effectively purifies rough scheelite concentrate and improves grade of scheelite concentrate. Meanwhile, the neutral flotation reduces influence on the environment.

Claims

1. A method of a flotation separation of calcium-bearing minerals, comprising: crushing and slurrying the calcium-bearing minerals to be treated to obtain an ore slurry, and adding a flotation collector into the ore slurry for the flotation separation; wherein the flotation collector comprises a 2-cyano-N-(substituted carbamoyl)acetamide compound, and the 2-cyano-N-(substituted carbamoyl)acetamide compound is at least one compound having a structural formula as Formula 1; ##STR00003## R is a hydrogen group, a C.sub.1-C.sub.15 alkyl group, a C.sub.3-C.sub.15 cycloalkyl group, a propenyl group, an ethynyl group, a phenyl group, a benzyl group, or a benzyloxy group; wherein a substituent group is allowed to be attached to an aromatic ring of the phenyl group, the benzyl group, and the benzyloxy group.

2. The method according to claim 1, wherein the R is independently a hydrogen atom, a C.sub.2-C.sub.6 alkyl group, or a C.sub.3-C.sub.6 alkenyl group.

3. The method according to claim 1, wherein the calcium-bearing minerals are two or more minerals selected from scheelite and calcium-bearing gangue.

4. The method according to claim 3, wherein the flotation separation is to separate scheelite from the calcium-bearing gangue.

5. (canceled)

6. The method according to claim 1, wherein the flotation collector further comprises an auxiliary collector; and the auxiliary collector comprises at least one of collectors of a hydroximic acid compound, a fatty acid compound, a phosphoric acid compound, a dodecylamine compound, and an amino acid compound.

7. The method according to claim 1, wherein the flotation collector comprises 70-98 parts by weight of the 2-cyano-N-(substituted carbamoyl)acetamide compound and less than or equal to 30 parts by weight of an auxiliary collector.

8. The method according to claim 1, wherein the ore slurry has a pH of 6-10, in the flotation separation; and the 2-cyano-N-(substituted carbamoyl)acetamide compound has a dosage of more than or equal to 0.8×10.sup.−5 mol/L in the flotation separation.

9. A flotation reagent for calcium-bearing minerals, comprising the 2-cyano-N-(substituted carbamoyl)acetamide compound according to claim 1.

10. The flotation reagent for the calcium-bearing minerals according to claim 9, wherein the flotation reagent further comprises an auxiliary collector; the auxiliary collector comprises at least one of collectors of a hydroximic acid compound, a fatty acid compound, a phosphoric acid compound, a dodecylamine compound, and an amino acid compound; the flotation reagent comprises 70-98 parts by weight of the 2 cyano-N-(substituted carbamoyl)acetamide compound and less than or equal to 30 parts by weight of the auxiliary collector.

11. The method according to claim 3, wherein the calcium-bearing gangue comprises at least one of fluorite and calcite.

12. The 2-cyano-N-(substituted carbamoyl)acetamide compound according to claim 5, wherein the flotation reagent comprises 80-98 parts by weight of the 2-cyano-N-(substituted carbamoyl)acetamide compound and 2-20 parts by weight of an auxiliary collector.

13. The method according to claim 2, wherein the ore slurry has a pH of 6-10 in the flotation separation; and the 2-cyano-N-(substituted carbamoyl)acetamide compound has a dosage of more than or equal to 0.8×10.sup.−5 mol/L in the flotation separation.

14. The method according to claim 3, wherein the ore slurry has a pH of 6-10 in the flotation separation; and the 2-cyano-N-(substituted carbamoyl)acetamide compound has a dosage of more than or equal to 0.8×10.sup.−5 mol/L in the flotation separation.

15. The method according to claim 4, wherein the ore slurry has a pH of 6-10 in the flotation separation; and the 2-cyano-N-(substituted carbamoyl)acetamide compound has a dosage of more than or equal to 0.8×10.sup.−5 mol/L in the flotation separation.

16. The method according to claim 6, wherein the ore slurry has a pH of 6-10 in the flotation separation; and the 2-cyano-N-(substituted carbamoyl)acetamide compound has a dosage of more than or equal to 0.8×10.sup.−5 mol/L in the flotation separation.

17. The method according to claim 7, wherein the ore slurry has a pH of 6-10 in the flotation separation; and the 2-cyano-N-(substituted carbamoyl)acetamide compound has a dosage of more than or equal to 0.8×10.sup.−5 mol/L in the flotation separation.

18. The flotation reagent for the calcium-bearing minerals according to claim 9, wherein the R in the 2-cyano-N-(substituted carbamoyl)acetamide compound is independently a hydrogen atom, a C.sub.2-C.sub.6 alkyl group, or a C.sub.3-C.sub.6 alkenyl group.

19. The flotation reagent for the calcium-bearing minerals according to claim 9, wherein the calcium-bearing minerals are two or more minerals selected from scheelite and calcium-bearing gangue.

20. The flotation reagent for the calcium-bearing minerals according to claim 18, wherein the flotation separation is to separate the scheelite from the calcium-bearing gangue.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG. 1 is a flowchart of flotation in Example 1;

[0037] FIG. 2 is a recovery rate diagram of a flotation reagent in Example 1 of the present disclosure;

[0038] FIG. 3 is a recovery rate diagram of a flotation reagent in Example 2;

[0039] FIG. 4 is a recovery rate diagram of a flotation reagent in Example 3;

[0040] FIG. 5 is a flowchart of flotation in Example 4 and Comparative example 1;

[0041] FIG. 6 is a nuclear magnetic resonance (H1-NMR) spectrum of the collector 2-cyano-N-(substituted carbamoyl)acetamide compound (in Formula 1, R is an ethyl group) according to the present disclosure; and

[0042] FIG. 7 is a .sup.3C-NMR spectrum of the collector 2-cyano-N-(substituted carbamoyl)acetamide compound (in Formula 1, R is an ethyl group) according to the present disclosure.

DETAILED DESCRIPTION

[0043] Single minerals of scheelite, fluorite and calcite and mixed calcium-bearing minerals of two or more of the scheelite, the fluorite and the calcite are used as examples to illustrate an effect of the present disclosure.

[0044] A 2-cyano-N-(substituted carbamoyl)acetamide compound can be synthesized with reference to existing methods. For example, a synthetic route is as follows:

##STR00002##

[0045] N—R substituted urea (Formula A) and 2-cyanoacetic acid (Formula B) are added to anhydrous acetic acid and react at 70° C. to obtain a target product (Formula 1).

[0046] In the following cases, unless otherwise stated, used minerals have a composition as shown in Table 1:

TABLE-US-00001 TABLE 1 Original grade and origin of minerals Mineral CaF.sub.2 CaCO.sub.3 CaWO.sub.4 Types (wt %) (wt %) (wt %) Origin Fluorite 99.8 — — Hunan Calcite — 99.7 — Hunan Scheelite — — 99.3 Sichuan

Example 1

[0047] In order to verify a separation effect of single use of a flotation collector in the example on each component in calcium-bearing mixed minerals, scheelite, fluorite and calcite concentrates from Hunan and Sichuan were used. A process shown in FIG. 1 was used. 3 groups were set in the experiment, the flotation collector in the example was used as a flotation reagent for flotation of the different calcium-bearing minerals, the flotation process had the same parameters in each group, the only difference was types of the flotation calcium-bearing minerals, thus flotation and separation effects of the flotation collector in the example were compared.

[0048] The flotation collector of the present disclosure: a 2-cyano-N-(substituted carbamoyl)acetamide compound (in Formula 1, R is an ethyl group, namely, in Formula 1, R is a compound of an ethyl group) and terpilenol at a ratio of 0.095 mol:0.005 mol were added to 1 L of deionized water (at a concentration of 0.1 mol/L) and magnetically stirred at 65° C. for 30 min, such that the reagent was fully mixed and sealed for later use.

[0049] A specific operation was as follows: an ore concentrate (at a particle size of 3 mm-0.5 mm) was dry-ground for 15 min (the concentrate had a particle size of 0.0740-0.0374 mm after the dry-grinding by using a horizontal ball mill and had a grinding concentration of 35-40%), 2 g of the ground calcium-bearing concentrate (fluorite, calcite or scheelite) was weighed in each group and poured into a 40 mL flotation cell, 30 mL of deionized water was added, the flotation collector of the example was added, an appropriate amount of deionized water was supplemented, stirring was conducted for 3 min, foams were scraped for 3 min, the concentrate was scraped to a concentrate basin with the foams, tailings remained in the flotation cell, the concentrate and the tailings were filtered, dried and weighed separately, the grade of the concentrate was detected and a recovery rate was calculated.

[0050] FIG. 2 shows a recovery rate of scheelite, fluorite and calcite concentrates in Example 1 under different dosages of the reagent. (The flotation collector in the example was the flotation reagent and an ore slurry had a pH of 7).

[0051] It can be seen from FIG. 2 that within a dosage range of the reagent to be tested, the flotation reagent in the example had a relatively strong ability to selectively collect the complex calcium-bearing minerals, especially almost did not collect the scheelite, thus can efficiently separate the scheelite from the fluorite and the calcite, and can be used for removing impurities in the scheelite concentrate in industry. The result meant that the flotation collector in the example can efficiently separate the fluorite from the scheelite and separate the fluorite from the calcite to some extent.

TABLE-US-00002 TABLE 2 Flotation results of Example 1 Concentration of flotation reagent of the present Recovery rate (%) disclosure (mol/L) Fluorite Calcite Scheelite 1 × 10.sup.−5 27.23 11.07 0.9 5 × 10.sup.−5 33.38 14.97 1.28 1 × 10.sup.−4 41.02 18.46 1.48 2.5 × 10.sup.−4   49.01 29.07 2.1 5 × 10.sup.−4 63.38 34.97 2.28 1 × 10.sup.−3 71.02 39.46 2.48 2.5 × 10.sup.−3   87.27 45.08 2.12 5 × 10.sup.−3 91.39 53.64 2.34

Example 2

[0052] A 2-cyano-N-(substituted carbamoyl)acetamide compound (in Formula 1, R was an ethyl group), benzohydroxamic acid and terpilenol at a ratio of 0.080 mol:0.015 mol:0.005 mol were added to 1 L of deionized water (at a concentration of 0.1 mol/L) and magnetically stirred at 65° C. for 30 min, such that a reagent was fully mixed and sealed for later use.

[0053] Scheelite, fluorite and calcite concentrates from Hunan and Sichuan were used. A process shown in FIG. 1 was used. Three groups were set in the experiment, the compound flotation reagent in the example was used, the flotation process had the same parameters in the three groups, the only difference was types of oxide ore single minerals, thus flotation and separation effects of the compound flotation reagent in the example were compared.

[0054] An ore concentrate (at a particle size of 3 mm-0.5 mm) was dry-ground for 15 min (the concentrate had a particle size of 0.0740-0.0374 mm after the dry-grinding by using a horizontal ball mill and had a grinding concentration of 35-40%, where the scheelite, the fluorite and the calcite were ground at a pH of 7, 9 and 6 separately), 2 g of the ground concentrate was weighed in each group and poured into a 40 mL flotation cell, 30 mL of deionized water was added, the two flotation reagents at a dosage of 5×10.sup.−4 mol/L were added, an appropriate amount of deionized water was supplemented, stirring was conducted for 3 min, foams were scraped for 3 min, the concentrate was scraped to a concentrate basin with the foams, tailings remained in the flotation cell, the concentrate and the tailings were filtered, dried and weighed separately, and a recovery rate was calculated.

[0055] FIG. 3 shows a recovery rate of scheelite, fluorite and calcite concentrates in Example 2 under different dosages of the reagent. (The flotation reagent in the example was used and an ore slurry had a pH of 7).

[0056] It can be seen from FIG. 3 that within a dosage range of the reagent to be tested, the flotation reagent in the example had a relatively strong ability to selectively collect the complex oxide ores, especially almost did not collect the scheelite, thus can efficiently separate the scheelite from the fluorite and the calcite, and can be used for removing impurities in the scheelite concentrate in industry. When the reagent had a very low dosage (1×10.sup.−5 mol/L), the compound flotation reagent in the example had a recovery rate of the fluorite of about 50%, a recovery rate of the calcite of 19.07%, and a recovery rate of the scheelite of only 1.1%, which meant that the compound flotation reagent in the example can efficiently separate the fluorite from the scheelite and separate the fluorite from the calcite to some extent.

[0057] As the concentration of the reagent increased from 1×10.sup.−5 mol/L to 5×10.sup.−4 mol/L, the compound flotation reagent in the example had a recovery rate of the fluorite increased by 32.38% and when the concentration of the reagent was 5×10.sup.−4 mol/L, the recovery rate was 81.39%; the compound flotation reagent in the example had a recovery rate of the calcite increased by 24.57% and when the concentration of the reagent was 5×10.sup.−4 mol/L, the recovery rate was 43.64%; but the recovery rate of the scheelite was kept below 3%. The result meant that as the dosage of the reagent increased, the compound flotation reagent in the example further improved a separation performance of the fluorite, the calcite and the scheelite.

TABLE-US-00003 TABLE 3 Flotation results of Example 2 Concentration of flotation reagent of the present Recovery rate (%) disclosure (mol/L) Fluorite Calcite Scheelite 1 × 10.sup.−5 49.01 19.07 1.1 5 × 10.sup.−5 53.38 24.97 1.28 1 × 10.sup.−4 61.02 29.46 1.48 2.5 × 10.sup.−4   67.27 35.08 1.12 5 × 10.sup.−4 81.39 43.64 1.34

Example 3

[0058] A pH of an ore slurry is one of the most important parameters to control flotation and may directly affect electrical behaviors of mineral surfaces, cationic hydrolysis, flotation activity of reagents, adsorption properties, and dispersion and coagulation of the ore slurry. A flotation experiment was conducted at different pH values. The optimal pH of the flotation reagent of the present disclosure was investigated for separating fluorite, scheelite and calcite.

[0059] A 2-cyano-N-(substituted carbamoyl)acetamide compound (in Formula 1, R is an ethyl group), benzohydroxamic acid and terpilenol at a ratio of 0.085 mol:0.010 mol:0.005 mol were added to 1 L of deionized water (at a concentration of 0.1 mol/L) and magnetically stirred at 65° C. for 30 min, such that the reagent was fully mixed and sealed for later use.

[0060] Scheelite, fluorite and calcite concentrates from Hunan and Sichuan were used. A process shown in FIG. 1 was used. Three groups were set in the experiment, the compound flotation reagent in the example was used as the only flotation reagent, the flotation process had the same parameters in the three groups, the only difference was types of oxide ore single minerals, thus flotation and separation effects of the compound flotation reagent in the example were compared.

[0061] A specific operation was as follows: an ore concentrate (at a particle size of 3 mm-0.5 mm) was dry-ground for 15 min (the concentrate had a particle size of 0.0740-0.0374 mm after the dry-grinding by using a horizontal ball mill and had a grinding concentration of 35-40%). 2 g of the ground concentrate was weighed in each group and poured into a 40 mL flotation cell, 30 mL of deionized water was added, the flotation reagents at a dosage of 5×10.sup.−4 mol/L were added, an appropriate amount of deionized water was supplemented, stirring was conducted for 3 min, a pH adjuster (hydrochloric acid or sodium hydroxide) was added to adjust a flotation system to a specific pH, stirring was conducted for 3 min, foams were scraped for 3 min, the concentrate was scraped to a concentrate basin with the foams, tailings remained in the flotation cell, the concentrate and the tailings were filtered, dried and weighed separately, and a recovery rate was calculated.

[0062] A pH gradient set in the experiment was 4, 5, 6, 7, 8, 9 and 10. The calcite had a main component of CaCO.sub.3, thus the calcite would decompose under an acidic condition. A pH of a solution cannot be stabilized under the acidic condition after the calcite was added, such that the pH gradient of the calcite was 6, 7, 8, 9 and 10.

[0063] FIG. 4 shows a recovery rate of the scheelite, fluorite and calcite concentrates in Example 3 under different pH. (The flotation reagent in the example had a concentration of 5×10.sup.−4 mol/L, fluorite flotation had an initial pH of 7, calcite flotation had an initial pH of 9, scheelite flotation had an initial pH of 6, the pH was all adjusted to under 7 for a flotation experiment, and pH adjusters were a sodium hydroxide solution and a hydrochloric acid solution).

[0064] It can be seen from Example 3 that the flotation reagent of the present disclosure had a stable collection performance on the three oxide ores of the fluorite, the calcite and the scheelite at a pH between 6-8. A recovery rate of the useful mineral fluorite was higher than 75% and meanwhile a recovery rate of the scheelite was lower than 5%. The results indicated that the flotation reagent in the example can effectively and highly selectively collect the complex calcium-bearing minerals in a green neutral acid-base range (with a pH between 6-8).

TABLE-US-00004 TABLE 4 Flotation results of Example 3 pH value of Recovery rate (%) flotation system Fluorite Calcite Scheelite 4 51.85 — 2.98 5 68.95 — 3.87 6 78.93 43.64 3.79 7 81.39 46.07 3.97 8 75.46 46.82 3.87 9 58.62 48.82 4.58 10 46.67 53.93 4.73

Example 4

[0065] In order to verify a separation effect of a flotation reagent in the example on each component in calcium-bearing mixed minerals, scheelite, fluorite and calcite concentrates from Hunan and Sichuan were mixed uniformly at different proportions to obtain artificially mixed minerals 1.sup.#-4 .sup.#of the three concentrates. A process shown in FIG. 5 was used. 4 groups were set in the experiment, a benzohydroxamic acid compound reagent (in Comparative example 1) was used as a flotation reagent to be compared with the flotation reagent of the present disclosure, the flotation process had the same parameters in each group, the only difference was types of the flotation reagents, thus flotation effects of the benzohydroxamic acid and the flotation reagent in the example were compared.

[0066] Flotation reagent of the present disclosure: a 2-cyano-N-(substituted carbamoyl)acetamide compound (in Formula 1, R is an ethyl substituted, benzohydroxamic acid and terpilenol at a ratio of 0.090 mol:0.005 mol:0.005 mol were added to 1 L of deionized water (at a concentration of 0.1 mol/L) and magnetically stirred at 65° C. for 30 min, such that the reagent was fully mixed and sealed for later use.

[0067] Benzohydroxamic acid compound reagent (Comparative example 1): benzohydroxamic acid and terpilenol at a ratio of 0.095 mol:0.005 mol were added to 1 L of deionized water (at a concentration of 0.1 mol/L) and magnetically stirred at 65° C. for 30 min, such that the reagent was fully mixed and sealed for later use.

[0068] A specific operation was as follows: an ore concentrate (at a particle size of 3 mm-0.5 mm) was dry-ground for 15 min (the concentrate had a particle size of 0.0740-0.0374 mm after the dry-grinding by using a horizontal ball mill and had a grinding concentration of 35-40%), 2 g of the ground and uniformly mixed concentrate according to a proportion was weighed in each group and poured into a 40 mL flotation cell, 30 mL of deionized water was added, the benzohydroxamic acid and the flotation reagent of the example at a concentration of 5×10.sup.−4 mol/L were added, an appropriate amount of deionized water was supplemented, and an obtained ore slurry had a pH of 7; and stirring was conducted for 3 min, foams were scraped for 3 min, the concentrate was scraped to a concentrate basin with the foams, tailings remained in the flotation cell, the concentrate and the tailings were filtered, dried and weighed separately, the grade of the concentrate was detected and a recovery rate was calculated.

[0069] The artificially mixed minerals 1.sup.#-4 .sup.#in the example had a specific mixing ratio as follows:

[0070] The artificially mixed mineral 1.sup.#: 1 g of fluorite and 1 g of calcite were mechanically stirred at a room temperature for 10 min to fully mix the minerals, and the mixed mineral was sealed for later use.

[0071] The artificially mixed mineral 2.sup.#: 1 g of fluorite and 1 g of scheelite were mechanically stirred at a room temperature for 10 min to fully mix the minerals, and the mixed mineral was sealed for later use.

[0072] The artificially mixed mineral 3.sup.#: 1 g of calcite and 1 g of scheelite were mechanically stirred at a room temperature for 10 min to fully mix the minerals, and the mixed mineral was sealed for later use.

[0073] The artificially mixed mineral 4 .sup.#: 0.5 g of fluorite, 0.5 g of calcite and 1 g of scheelite were mechanically stirred at a room temperature for 10 min to fully mix the minerals, and the mixed mineral was sealed for later use.

[0074] Table 5 shows grades of each component in the artificially mixed minerals 1.sup.#-4 .sup.#in Example 4.

TABLE-US-00005 TABLE 5 Composition and proportion of artificially mixed minerals Mineral Compo- Grade (%) Types sition Proportion CaF.sub.2 CaCO.sub.3 CaWO.sub.4 Artificially Fluorite: 1:1:0 49.90 49.90 — mixed Calcite: mineral 1.sup.# Scheelite Artificially Fluorite: 1:0:1 49.90 — 49.70 mixed Calcite: mineral 2.sup.# Scheelite Artificially Fluorite: 0:1:1 — 49.90 49.70 mixed Calcite: mineral 3.sup.# Scheelite Artificially Fluorite: 1:1:2 24.95 24.95 49.70 mixed Calcite: mineral 4.sup.# Scheelite

[0075] Table 6 shows a flotation recovery rate and grade of fluorite, calcite and scheelite in Example 4. (In the example, the flotation reagents had a concentration of 5×10.sup.−4 mol/L and the fluorite, the calcite and the scheelite had an initial pH value adjusted to 7.)

TABLE-US-00006 TABLE 6 Flotation results of Example 4 (The flotation reagent of the present disclosure or the benzohydroxamic acid compound reagent had a concentration of 5 × 10.sup.−4 mol/L and a pH was 7.) Recovery rate Mineral Grade (%) (%) Types Flotation reagent CaF.sub.2 CaCO.sub.3 CaWO.sub.4 CaF.sub.2 CaCO.sub.3 CaWO.sub.4 Artificially Flotation reagent of the 65.55 34.40 — 80.24 42.13 — mixed mineral present disclosure 1.sup.# Benzohydroxamic acid 63.84 36.11 — 93.21 52.72 — compound reagent Artificially Flotation reagent 95.01 — 4.95 89.52 — 4.67 mixed mineral Benzohydroxamic acid 54.25 — 45.72 95.27 — 80.28 2.sup.# compound reagent Artificially Flotation reagent — 91.38 8.52 — 43.77 4.08 mixed mineral Benzohydroxamic acid — 39.56 60.35 — 51.27 78.21 3.sup.# compound reagent Artificially Flotation reagent 80.70 16.67 2.59 78.12 32.27 5.02 mixed mineral Benzohydroxamic acid 57.86 16.87 25.19 92.17 53.76 80.21 4.sup.# compound reagent

[0076] It can be seen from Table 6 that when the flotation reagent had a concentration of 5×10.sup.−4 mol/L, the flotation reagent in the example had a significantly stronger ability to collect the fluorite and the calcite in the artificially mixed minerals 1.sup.#-4 .sup.#than the benzohydroxamic acid. Meanwhile, the flotation reagent in the example had a significantly lower ability to collect the scheelite than the benzohydroxamic acid. According to the flotation results, compared with the traditional sulfide flotation reagent benzohydroxamic acid, the flotation reagent in the example had a significantly improved separation effect and a recovery rate of useful minerals was also significantly improved. It can be seen that the flotation reagent in the example was more effective than the traditional oxide ore flotation reagent benzohydroxamic acid and had a better separation effect.

Example 5

[0077] In order to verify a separation effect of a flotation reagent in the example on each component in calcium-bearing mixed minerals, scheelite, fluorite and calcite concentrates from Hunan and Sichuan were mixed uniformly at different proportions to obtain artificially mixed minerals 1.sup.#-4 .sup.#of the three concentrates. A process shown in FIG. 5 was used. 4 groups were set in the experiment, corresponding compound flotation reagents of the collectors of the present disclosure with different R groups were used as flotation reagents and compared, the flotation process had the same parameters in each group, the only difference was types of the flotation reagents, thus flotation effects of the flotation reagents in the example were compared.

[0078] Flotation reagent 1.sup.#: a 2-cyano-N-(substituted carbamoyl)acetamide compound (in Formula 1, R is a pentyl group), benzohydroxamic acid and terpilenol at a ratio of 0.090 mol:0.005 mol:0.005 mol were added to 1 L of deionized water (at a concentration of 0.1 mol/L) and magnetically stirred at 65° C. for 30 min, such that the reagent was fully mixed and sealed for later use.

[0079] Flotation reagent 2.sup.#: a 2-cyano-N-(substituted carbamoyl)acetamide compound (in Formula 1, R is a phenyl group), benzohydroxamic acid and terpilenol at a ratio of 0.090 mol:0.005 mol:0.005 mol were added to 1 L of deionized water (at a concentration of 0.1 mol/L) and magnetically stirred at 65° C. for 30 min, such that the reagent was fully mixed and sealed for later use.

[0080] A specific operation was as follows: an ore concentrate (at a particle size of 3 mm-0.5 mm) was dry-ground for 15 min (the concentrate had a particle size of 0.0740-0.0374 mm after the dry-grinding by using a horizontal ball mill and had a grinding concentration of 35-40%), 2 g of the ground and uniformly mixed concentrate according to a proportion was weighed in each group and poured into a 40 mL flotation cell, 30 mL of deionized water was added, the benzohydroxamic acid and the flotation reagent of the example at a concentration of 5×10.sup.−4 mol/L were added, an appropriate amount of deionized water was supplemented, and an obtained ore slurry had a pH of 7; and stirring was conducted for 3 min, foams were scraped for 3 min, the concentrate was scraped to a concentrate basin with the foams, tailings remained in the flotation cell, the concentrate and the tailings were filtered, dried and weighed separately, the grade of the concentrate was detected and a recovery rate was calculated.

[0081] The artificially mixed minerals 1.sup.#-4 .sup.#in the example had a specific mixing ratio as follows:

[0082] The artificially mixed mineral 1.sup.#: 1 g of fluorite and 1 g of calcite were mechanically stirred at a room temperature for 10 min to fully mix the minerals, and the mixed mineral was sealed for later use.

[0083] The artificially mixed mineral 2.sup.#: 1 g of fluorite and 1 g of scheelite were mechanically stirred at a room temperature for 10 min to fully mix the minerals, and the mixed mineral was sealed for later use.

[0084] The artificially mixed mineral 3.sup.#: 1 g of calcite and 1 g of scheelite were mechanically stirred at a room temperature for 10 min to fully mix the minerals, and the mixed mineral was sealed for later use.

[0085] The artificially mixed mineral 4 .sup.#: 0.5 g of fluorite, 0.5 g of calcite and 1 g of scheelite were mechanically stirred at a room temperature for 10 min to fully mix the minerals, and the mixed mineral was sealed for later use.

[0086] Table 7 shows grades of each component in artificially mixed minerals 1.sup.#-4 .sup.#in Example 5.

TABLE-US-00007 TABLE 7 Composition and proportion of artificially mixed minerals Mineral Compo- Grade (%) Types sition Proportion CaF.sub.2 CaCO.sub.3 CaWO.sub.4 Artificially Fluorite: 1:1:0 49.90 49.90 — mixed Calcite: mineral 1.sup.# Scheelite Artificially Fluorite: 1:0:1 49.90 — 49.70 mixed Calcite: mineral 2.sup.# Scheelite Artificially Fluorite: 0:1:1 — 49.90 49.70 mixed Calcite: mineral 3.sup.# Scheelite Artificially Fluorite: 1:1:2 24.95 24.95 49.70 mixed Calcite: mineral 4.sup.# Scheelite

[0087] Table 8 shows a flotation recovery rate and grade of fluorite, calcite and scheelite in Example 5.

TABLE-US-00008 TABLE 8 Flotation results of Example 5 (The flotation reagent of the present disclosure had a concentration of 5 × 10.sup.−4 mol/L and a pH was 7.) Recovery rate Grade (%) (%) Mineral Types Flotation reagent CaF.sub.2 CaCO.sub.3 CaWO.sub.4 CaF.sub.2 CaCO.sub.3 CaWO.sub.4 Artificially mixed Flotation reagent 1.sup.# 65.35 34.65 96.81 51.32 — mineral 1.sup.# Flotation reagent 2.sup.# 62.88 37.12 98.81 58.32 — Artificially mixed Flotation reagent 1.sup.# 93.12 6.88 97.87 — 7.23 mineral 2.sup.# Flotation reagent 2.sup.# 92.39 7.61 99.86 — 8.22 Artificially mixed Flotation reagent 1.sup.# 85.58 14.42 — 54.23 9.14 mineral 3.sup.# Flotation reagent 2.sup.# 85.10 14.90 — 62.65 10.97 Artificially mixed Flotation reagent 1.sup.# 59.22 35.94 4.84 98.67 59.88 8.07 mineral 4.sup.# Flotation reagent 2.sup.# 58.36 35.97 5.62 99.32 61.21 9.65

[0088] To sum up, the flotation reagent of Formula 1 of the present disclosure had a good direct flotation collection of fluorite and calcite, had a reverse flotation effect on scheelite, and can selectively separate the scheelite from calcium-bearing gangue. (such as the fluorite and the calcite).