A pyrite inhibitor and its preparation method and application

Abstract

The present invention discloses a pyrite inhibitor, its preparation method, and application. The preparation method specifically comprises: grinding sawdust and then pyrolyzing it under a nitrogen atmosphere; condensing and collecting the gas from the pyrolysis product to obtain a pyrolysis liquid, namely the pyrite inhibitor. The present invention innovatively uses pine sawdust pyrolysis liquid as a pyrite inhibitor and applies it to the flotation separation of lead-sulfur or copper-sulfur. This not only achieves excellent flotation separation effects, but also enables high-value utilization of biomass pyrolysis products, helps save mineral processing costs, and has good social, environmental, and economic benefits.

Description

Technical Field

[0001] The present invention belongs to the technical field of mineral processing, and in particular relates to a pyrite inhibitor and a preparation method and application thereof. Background Art

[0002] Pyrite is often associated with useful minerals such as galena and chalcopyrite. Polymetallic sulfide ores are generally separated by suppressing pyrite and flotating galena and chalcopyrite to achieve separation of sulfide minerals.

[0003] Galena and pyrite have similar floatability when exposed to collectors. To effectively inhibit pyrite, researchers have developed inhibitors such as sulfite, potassium permanganate, hydrogen peroxide, EDTA, polyacrylamide, and pectin. However, these agents suffer from high dosages and production costs. Therefore, lime remains the preferred agent. However, high lime usage can easily lead to scaling and blockage in pipelines and flotation equipment, significantly increasing maintenance times during daily operations.

[0004] Chalcopyrite and pyrite have similar floatability under the action of collectors. To achieve flotation separation of copper and sulfur, an agent is required to suppress pyrite flotation. Currently, literature has reported on organic macromolecular inhibitors such as sodium carboxymethyl cellulose, modified cellulose inhibitors, sodium humate, and sodium lignin sulfonate. However, these inhibitors have poor selectivity and exhibit a certain inhibitory effect on chalcopyrite. Furthermore, the use of caustic soda, sodium sulfide, and water glass as modifiers is complex to produce and expensive. Currently, high-alkali flotation processes are widely used both domestically and internationally. This involves using lime as a depressant to adjust the pH to above 12 to suppress pyrite and ultimately separate copper and sulfur. However, high-alkali flotation processes have numerous drawbacks. For example, lime not only suppresses pyrite but also chalcopyrite to a certain extent. Excessive amounts of lime can lead to gangue entrainment, reducing the grade of the copper concentrate. It can also cause scaling in flotation equipment and slurry pipelines, increasing maintenance requirements. Furthermore, subsequent pyrite recovery consumes significant amounts of sulfuric acid for activation.

[0005] Therefore, there is an urgent need to develop a pyrite inhibitor with strong inhibitory ability and good selectivity. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the object of the present invention is to provide a pyrite inhibitor with strong inhibitory ability and good selectivity, and a preparation method and application thereof.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] The preparation method of the pyrite inhibitor provided by the present invention comprises the following steps:

[0009] 1) Grind the sawdust and perform pyrolysis under a protective atmosphere;

[0010] 2) Condensing and collecting the gas of the pyrolysis product to obtain a pyrolysis liquid, namely the pyrite inhibitor.

[0011] Preferably, in step 1), the sawdust is ground to a particle size of less than 2 mm. If the particle size is too large, a longer reaction time is required.

[0012] Preferably, in step 1), the wood chips are pine wood chips.

[0013] Preferably, in step 1), the pyrolysis temperature is 700°C to 800°C, and the holding time is 0.3 to 1.0 h. If the pyrolysis temperature is too low, the content of the active ingredient in the pyrolysis solution is insufficient, while if the temperature is too high, excessive energy consumption is caused. If the holding time is too short, the yield is insufficient, while if the holding time is too long, it also leads to high energy consumption.

[0014] Preferably, in step 1), the protective atmosphere is nitrogen. If the oxygen content is high, the yield of the pyrolysis solution will be reduced.

[0015] The pyrite inhibitor is prepared according to the above preparation method.

[0016] The present invention also provides an application of the pyrite inhibitor in lead-sulfur flotation separation, comprising the following steps:

[0017] S1. Grinding the raw ore to obtain slurry;

[0018] S2. Add zinc sulfate, ethyl xanthate, and No. 2 oil to the slurry for mixed flotation of galena and pyrite to obtain a lead-sulfur mixed concentrate;

[0019] S3. A combined inhibitor is added to the lead-sulfur mixed concentrate, and then a collector is added to perform lead roughing to obtain a crude lead concentrate and crude lead tailings; the combined inhibitor is lime + the pyrite inhibitor;

[0020] S4. The lead concentrate is subjected to 2 to 3 lead beneficiation steps to obtain a lead concentrate;

[0021] S5. The crude lead tailings are subjected to 2 to 3 lead scavenging processes to obtain lead tailings, i.e., sulfur concentrate.

[0022] Preferably, in step S1, the particle size of the ground product is -0.074 mm, accounting for 65% to 80%. If the particle size is too coarse or too fine, the grade and recovery rate of the galena will be reduced.

[0023] Preferably, in step S3, the combined inhibitor is added by first adding lime and then adding the pyrite inhibitor. The amount of lime added is 1000-2000 g / t, and the amount of pyrite inhibitor added is 300-1000 g / t. The main function of lime is to provide a suitable pH environment for the pyrite inhibitor, while also having a weak inhibitory effect on pyrite.

[0024] Specifically, in step S3, 1000-2000 g / t of lime is first added to the lead-sulfur mixed concentrate, and the mixture is stirred for 1-5 minutes to adjust the slurry pH to 8.5-9.5. Then, 300-1000 g / t of the pyrite inhibitor is added, and the mixture is stirred for 1-5 minutes. Finally, ethyl dithiocarbamide is added as a collector to perform lead roughing to obtain lead rough concentrate and lead rough tailings.

[0025] Specifically, in step S4, the lead crude concentrate is subjected to lead concentration 2 to 3 times, lime is added as an inhibitor before lead concentration, and each concentration time is 2 to 4 minutes to obtain lead concentrate.

[0026] Specifically, in step S5, the crude lead tailings are subjected to 2 to 3 lead scavenging processes, and ethyl dithiocarbamide is added as a collector before the lead scavenging process. Each scavenging process lasts for 2 to 4 minutes to obtain lead tailings.

[0027] The present invention also provides an application of the pyrite inhibitor in copper-sulfur flotation separation, comprising the following steps:

[0028] a) grinding the raw ore to obtain ore pulp;

[0029] b) adding a combined inhibitor to the ore pulp, and then adding a collector and a frother to perform copper roughing to obtain a copper rough concentrate and a copper rough tailing; the combined inhibitor is lime + the pyrite inhibitor;

[0030] c) subjecting the copper crude concentrate to 3-4 copper concentrations to obtain copper concentrate;

[0031] d) The copper coarse tailings are subjected to 2 to 3 copper scavenging processes to obtain copper tailings, i.e., sulfur concentrate.

[0032] Preferably, in step b), the combined inhibitor is added by first adding lime and then adding the pyrite inhibitor; the amount of lime used is 500-2000 g / t, and the amount of the pyrite inhibitor added is 300-1000 g / t. The main function of lime is to provide a suitable pH environment for the pyrite inhibitor and also to inhibit pyrite.

[0033] Specifically, in step b), 500-2000 g / t of lime is first added to the ore pulp, and the mixture is stirred for 1-5 minutes to adjust the pH value of the ore pulp to 8.0-9.5. Then, 300-1000 g / t of the pyrite inhibitor is added, and the mixture is stirred for 1-5 minutes. Then, a collector O-isopropyl-N-ethylthiocarbamate and a foaming agent No. 2 oil are added to perform copper roughing to obtain a copper rough concentrate and a copper rough tailings.

[0034] Preferably, in step c), the copper rough concentrate is subjected to copper concentration 3 to 4 times, lime is added as an inhibitor before copper concentration, and each concentration time is 2 to 4 minutes to obtain copper concentrate.

[0035] Preferably, in step d), the crude copper tailings are subjected to 2 to 3 copper scavenging processes, O-isopropyl-N-ethylthiocarbamate is added as a collector before the copper scavenging process, and each scavenging process lasts for 2 to 4 minutes to obtain copper tailings.

[0036] The present invention has the following advantages and beneficial effects:

[0037] 1) The present invention uses pine sawdust as a raw material to produce pyrite inhibitor, which has low production cost and effectively utilizes pine sawdust waste. In addition, the charcoal after pyrolysis can be used as a raw material for producing activated carbon, and the production process can achieve zero emissions.

[0038] 2) The pyrolysis product of pine sawdust is a complex mixture. Its application in other fields involves complex purification and impurity removal processes. However, the present invention uses it as a pyrite inhibitor for the flotation separation of copper-sulfur or lead-sulfur, which does not require prior purification and impurity removal, and has a simple production process, which is conducive to industrial application.

[0039] 3) The main components of the pyrolysis solution provided by the present invention include functional groups such as phenol, aldehyde, and carboxylic acid that can be selectively adsorbed on pyrite and iron sites, making pyrite hydrophilic and hindering the adsorption of collector molecules on the pyrite surface.

[0040] 4) The present invention innovatively uses pine sawdust pyrolysis liquid as an inhibitor in the flotation separation of lead-sulfur or copper-sulfur, which can make high-value utilization of biomass pyrolysis products and has a good flotation separation effect, helping to save mineral processing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is the flotation process of Examples 1 to 3.

[0042] Figure 2 This is the GC / MS total ion flow diagram of the liquid product (dissolved in n-hexane) pyrolyzed at 800°C in Example 1.

[0043] Figure 3 This is the GC / MS total ion flow diagram of the liquid product (dissolved in ethyl acetate) pyrolyzed at 800°C in Example 1.

[0044] Figure 4 This is the flotation process of Examples 4 to 6. DETAILED DESCRIPTION

[0045] The technical solutions of the present invention will be further clearly and completely described below in the form of specific embodiments. It is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0046] Unless otherwise specified, the experimental methods used in the examples of this invention are conventional methods. The materials and reagents used are commercially available unless otherwise specified. The g / t mentioned in this invention refers to the mass of the reagent added per ton of raw ore.

[0047] Example 1

[0048] The pyrite inhibitor is prepared by the following specific steps: 1) grinding pine sawdust to less than 2 mm; 2) pyrolyzing the sawdust under a nitrogen atmosphere at a temperature of 800°C for 0.5 h; 3) condensing and collecting the gas of the pyrolysis product to obtain a pyrolysis liquid, i.e., the pyrite inhibitor.

[0049] The main components and their mass fractions of the pyrite inhibitor prepared in this embodiment are as follows: (dissolved in n-hexane) 3-furfural 11.19%, isobutyric acid 9.10%, 3,3-dimethylacrylic acid 6.59%, hydroxyethyl methacrylate 6.20%, 3,4-dimethylfuran 5.64%, 5-methylfurfural 4.67%, phenol 1.36%, vinyl sorbate 1.35%, methylcyclopentenol 1.21%, 5 -Methyl-2-acetylfuran 1.19%, 2,3-dimethyl-2-cyclopentenone 1.15%; (dissolved in ethyl acetate): catechol 21.99%, 3,4-dihydroxytoluene 9.43%, 4-ethylbenzene 6.29%, 5-hydroxymethylfurfural 3.95%, 3-furfural 3.74%, phenol 3.66%, 3-methylcatechol 3.21%, m-cresol 2.21%, methylcyclopentenol 2.18%.

[0050] The prepared pyrite inhibitor was applied to the flotation test of a sulfur-containing lead-zinc ore. The main minerals in the ore were sphalerite, galena and pyrite, with a lead grade of 6.5% and an iron grade of 10.8%. Figure 1 The test steps are as follows:

[0051] (1) Grinding: The raw ore is ground using a ball mill, and the -0.074 mm particle size accounts for 71% of the grinding product;

[0052] (2) Lead-sulfur mixed flotation: 1800 g / t zinc sulfate, 120 g / t ethyl xanthate, and 15 g / t No. 2 oil are added to the pulp to carry out lead-sulfur mixed flotation. After one roughing and two scavenging steps, lead-sulfur mixed concentrate and tailings are obtained.

[0053] (3) Lead flotation: 2000 g / t of lime was added to the lead-sulfur mixed concentrate and stirred for 2 minutes. Subsequently, 500 g / t of pyrolysis solution was added and stirred for 2 minutes. 20 g / t of ethyl thiocyanate was added and a roughing operation was performed to obtain a roughing concentrate and a roughing tailing. The roughing concentrate was subjected to three rounds of cleaning to obtain a lead concentrate. Before each round of cleaning, 800 g / t, 400 g / t, and 0 g / t of lime were added, respectively. The roughing tailing was subjected to three rounds of scavenging. Before each round of scavenging, 9 g / t, 5 g / t, and 2 g / t of ethyl thiocyanate were added, respectively, to obtain a lead tailing, i.e., a sulfur concentrate. The flotation results are shown in Table 1.

[0054] Example 2

[0055] Compared with Example 1, this example differs in that the combined depressant used is 500 g / t 750°C pyrolysis solution + 2000 g / t lime, while other conditions and the dosage of the reagents remain the same. The flotation results are shown in Table 1.

[0056] Example 3

[0057] Compared with Example 1, this example differs in that the combined inhibitor used is 500 g / t 700°C pyrolysis liquid + 2000 g / t lime, and other conditions and the dosage of the reagents remain the same. The flotation results are shown in Table 1.

[0058] Comparative Example 1

[0059] Compared with Example 1, in this comparative example, only 2000 g / t of lime was added as a pyrite inhibitor, and no pine sawdust pyrolysis solution was added. Other conditions and the dosage of reagents remained the same. The flotation results are shown in Table 1.

[0060] Comparative Example 2

[0061] Compared with Example 1, in this comparative example, only 5000 g / t of lime was added as a pyrite inhibitor, and no pine sawdust pyrolysis solution was added. Other conditions and the dosage of reagents remained the same. The flotation results are shown in Table 1.

[0062] Comparative Example 3

[0063] Compared with Example 1, in this comparative example, only 500 g / t of 800°C pyrolysis solution was added as a pyrite inhibitor, and other conditions and reagent dosages remained unchanged. The flotation results are shown in Table 1.

[0064] Comparative Example 4

[0065] Compared with Example 1, the combined depressant used in this comparative example is 500 g / t 600°C pyrolysis liquid + 2000 g / t lime, with other conditions and reagent dosage remaining the same. The flotation results are shown in Table 1.

[0066] Comparative Example 5

[0067] Compared with Example 1, the combined depressant used in this comparative example is 500 g / t 900°C pyrolysis liquid + 2000 g / t lime, with other conditions and reagent dosage remaining the same. The flotation results are shown in Table 1.

[0068] Table 1 Flotation results of Examples 1 to 3 and Comparative Examples 1 to 5

[0069]

[0070]

[0071] As can be seen from the data in the table above, compared with Comparative Example 1, Examples 1, 2, and 3, the lead grade in the lead concentrate in Examples 1, 2, and 3 is significantly improved, indicating that the pyrolysis solution has a significant inhibitory effect on pyrite and can reduce the content of pyrite in the lead concentrate. Compared with Comparative Example 2, it can be seen that the lead grade and recovery rate in the lead concentrate of Examples 1, 2, and 3 are not much different, indicating that 500g / t pyrolysis solution + 2000g / t lime achieves the effect of 5000g / t lime, significantly reducing the amount of lime used. It can be seen from Comparative Example 3 that the inhibitory effect on pyrite when using pyrolysis solution alone is poor, and lime is required to adjust the pH. It can be seen from Comparative Example 4 that the inhibitory effect of 600°C pyrolysis solution on pyrite is weak. It can be seen from Comparative Example 5 that the 900°C pyrolysis solution has an inhibitory effect on galena.

[0072] Therefore, in lead-sulfur separation flotation, using pyrolysis solution and lime as a combined depressant can achieve highly efficient pyrite suppression, reducing lime usage by 3,000g / t and significantly reducing problems such as pipeline scaling and blockage caused by lime. This also allows for high-value utilization of the pyrolysis solution.

[0073] Example 4

[0074] The pyrite inhibitor prepared in Example 1 was applied to the flotation test of a sulfur-containing copper ore. The main sulfide minerals in the ore were chalcopyrite and pyrite, the main gangue minerals were silicate minerals, the copper grade was 1.47%, and the iron grade was 12.04%. The flotation process is as follows: Figure 4 The test steps are as follows:

[0075] (1) Grinding: The raw ore is ground using a ball mill, and the -0.074 mm particle size accounts for 85% of the grinding product;

[0076] (2) Flotation: 2500 g / t of lime was first added to the pulp and stirred for 2 minutes. Subsequently, 600 g / t of pyrolysis solution was added and stirred for 2 minutes. 70 g / t of O-isopropyl-N-ethylthiocarbamate was added as a collector and 15 g / t of No. 2 oil was added as a depressant. Roughing was performed to obtain a roughing concentrate and a roughing tailing. The roughing concentrate was subjected to three rounds of concentrating to obtain a copper concentrate. Before each round of concentrating, 400 g / t, 200 g / t, and 0 g / t of lime were added, respectively. The roughing tailing was subjected to three rounds of scavenging. Before each round of scavenging, 30 g / t, 15 g / t, and 5 g / t of O-isopropyl-N-ethylthiocarbamate were added, respectively, to obtain a tailing. The flotation results are shown in Table 2.

[0077] Example 5

[0078] Compared with Example 4, the combined depressant used in this example is 600 g / t 750°C pyrolysis solution + 2500 g / t lime, with other conditions and reagent dosage remaining the same. The flotation results are shown in Table 2.

[0079] Example 6

[0080] Compared with Example 4, the combined inhibitor used in this example is 600 g / t 700°C pyrolysis liquid + 2500 g / t lime, with other conditions and dosages remaining the same. The flotation results are shown in Table 2.

[0081] Comparative Example 6

[0082] Compared with Example 4, in this comparative example, only 2500 g / t of lime was added as a pyrite depressant, and other conditions and reagent dosages remained unchanged. The flotation results are shown in Table 2.

[0083] Comparative Example 7

[0084] Compared with Example 4, in this comparative example, only 8000 g / t of lime was added as a pyrite depressant, and other conditions and reagent dosages remained unchanged. The flotation results are shown in Table 2.

[0085] Comparative Example 8

[0086] Compared with Example 4, in this comparative example, only 600 g / t of 800°C pyrolysis solution was added as a pyrite depressant, and other conditions and reagent dosages remained unchanged. The flotation results are shown in Table 2.

[0087] Comparative Example 9

[0088] Compared with Example 4, the combined depressant used in this comparative example is 600 g / t 600°C pyrolysis liquid + 2500 g / t lime, with other conditions and dosages remaining the same. The flotation results are shown in Table 2.

[0089] Comparative Example 10

[0090] Compared with Example 4, the combined depressant used in this comparative example is 600 g / t 900°C pyrolysis solution + 2500 g / t lime, with other conditions and reagent dosage remaining the same. The flotation results are shown in Table 2.

[0091] Table 2 Flotation results of Examples 4 to 6 and Comparative Examples 6 to 10

[0092]

[0093]

[0094] Comparing Examples 4-6 with Comparative Example 6 shows that the copper grade in the concentrates of Examples 4-6 is significantly improved, indicating that the pyrolysis solution has a significant inhibitory effect on pyrite, reducing the pyrite content in the concentrate. Comparative Example 7 represents the optimal conditions for using lime alone. Example 4 achieves a 1.07 percentage point increase in grade and a 2.25 percentage point increase in recovery compared to Comparative Example 7, demonstrating that 600g / t 800°C pyrolysis solution + 2500g / t lime is slightly more effective than 8000g / t lime, while significantly reducing the amount of lime required. Comparative Example 8 shows that the inhibitory effect of pyrolysis solution alone on pyrite is poor, requiring lime to adjust the pH. Comparative Example 9 shows that the inhibitory effect of 600°C pyrolysis solution on pyrite is weak. Comparative Example 10 shows that the selectivity of the 900°C pyrolysis solution is poor, inhibiting chalcopyrite.

[0095] Therefore, in copper-sulfur separation flotation, using pyrolysis solution and lime as a combined depressant can achieve highly efficient pyrite suppression, reducing lime usage by 5,500g / t and significantly reducing problems such as pipeline scaling and blockage caused by lime. This also allows for high-value utilization of the pyrolysis solution.

Claims

1. An application of a pyrite inhibitor in lead-sulfur flotation separation comprises the following steps: S1. Grinding the raw ore to obtain slurry; S2. Add zinc sulfate, ethyl xanthate, and No. 2 oil to the slurry for mixed flotation of galena and pyrite to obtain a lead-sulfur mixed concentrate; S3. A combined inhibitor is added to the lead-sulfur mixed concentrate, and then a collector is added to perform lead roughing to obtain a crude lead concentrate and crude lead tailings; the combined inhibitor is a lime + pyrite inhibitor; S4. The lead concentrate is subjected to 2 to 3 lead beneficiation steps to obtain a lead concentrate; S5. The lead tailings are subjected to 2 to 3 lead scavenging steps to obtain lead tailings, i.e., sulfur concentrate; The pyrite inhibitor is prepared by a method comprising the following steps: 1) Grind the sawdust and pyrolyze it under a protective atmosphere; 2) condensing and collecting the gas of the pyrolysis product to obtain a pyrolysis liquid, i.e., the pyrite inhibitor; In step 1), the sawdust is pine sawdust; and the pyrolysis temperature is 700°C to 800°C.

2. The application according to claim 1, characterized in that In step S3, the combined inhibitor is added by first adding lime and then adding the pyrite inhibitor. The amount of lime added is 1000-2000 g / t, and the amount of pyrite inhibitor added is 300-1000 g / t.

3. The application according to claim 1, characterized in that The specific process of step S3 is as follows: first adding 1000-2000 g / t of lime to the lead-sulfur mixed concentrate, stirring for 1-5 minutes to adjust the slurry pH to 8.5-9.5, then adding 300-1000 g / t of the pyrite inhibitor, stirring for 1-5 minutes, and finally adding a collector to perform lead roughing to obtain lead rough concentrate and lead rough tailings.

4. An application of a pyrite inhibitor in copper-sulfur flotation separation comprises the following steps: a) Grinding the raw ore to obtain slurry; b) adding a combined inhibitor to the ore pulp, and then adding a collector and a frother to perform copper roughing to obtain a copper rough concentrate and a copper rough tailing; the combined inhibitor is a lime + pyrite inhibitor; c) subjecting the copper rough concentrate to 3-4 copper beneficiation steps to obtain copper concentrate; d) subjecting the crude copper tailings to 2-3 copper scavenging processes to obtain copper tailings, i.e., sulfur concentrate; The pyrite inhibitor is prepared by a method comprising the following steps: 1) Grind the sawdust and pyrolyze it under a protective atmosphere; 2) condensing and collecting the gas of the pyrolysis product to obtain a pyrolysis liquid, i.e., the pyrite inhibitor; In step 1), the sawdust is pine sawdust; and the pyrolysis temperature is 700°C to 800°C.

5. The use according to claim 1 or 4, characterized in that In step 1), the sawdust is ground into a particle size of less than 2 mm.

6. The use according to claim 1 or 4, characterized in that In step 1), the pyrolysis holding time is 0.3 to 1.0 h.

7. The use according to claim 4, characterized in that In step b), the combined inhibitor is added by first adding lime and then adding the pyrite inhibitor; the amount of lime used is 500-2000 g / t, and the amount of pyrite inhibitor added is 300-1000 g / t.

8. The use according to claim 4, characterized in that: The specific process of step b) is as follows: first, adding 500-2000 g / t of lime to the ore pulp, stirring for 1-5 minutes to adjust the ore pulp pH to 8.0-9.5, then adding 300-1000 g / t of the pyrite inhibitor, stirring for 1-5 minutes, and then adding a collector O-isopropyl-N-ethylthiocarbamate and a foaming agent No. 2 oil to perform copper roughing to obtain a copper rough concentrate and a copper rough tailings.

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