Flotation separation method for galena and pyrite

Abstract

The invention belongs to the technical field of mineral separation, and particularly relates to a flotation separation method for galena and pyrite. The method specifically comprises the steps that galena and pyrite are crushed, mixed and subjected to size mixing, then the pH is adjusted to 6.5-7.5, and ore pulp is obtained; adding a complexing agent into the ore pulp, and mixing the pulp; then a combined collecting agent is added, and size mixing is conducted; finally, adding a foaming agent and mixing; flotation is conducted after pulp mixing is finished, and concentrate and tailings are obtained respectively; the complexing agent is selected from EDTA-2Na; the combined collecting agent is composed of 3418A and a thiourea compound with the structural formula shown in the specification, and R is selected from vinyl, allyl or ethyl. Through the synergistic effect of the complexing agent and the combined collecting agent, the flotation composite agent can be suitable for flotation separation of lead-iron sulfide minerals under the neutral pH condition, then efficient separation of galena and pyrite is achieved, and the galena and pyrite flotation composite agent under the neutral pH condition is environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology, and in particular relates to a flotation separation method for galena and pyrite. Background Technology

[0002] Galena, the most widely distributed lead mineral in nature, is currently the main mineral raw material for industrial lead extraction, accounting for approximately 85% of global lead production. Meanwhile, pyrite, the most abundant sulfide mineral in the Earth's crust, plays a crucial role in sulfuric acid production, contributing over 60% of global sulfuric acid raw materials. In terms of geological characteristics, galena and pyrite often exhibit a close symbiotic relationship. Due to their high similarity in crystal structure and surface physicochemical properties, conventional flotation separation processes are often insufficient for effective separation.

[0003] The most common and effective method for separating lead-iron sulfide minerals at present is flotation. Research on flotation mainly focuses on the development of flotation reagents, especially utilizing the synergistic effect of combined collectors and developing novel collectors for selective collection of minerals. Traditional xanthate collectors have a strong adsorption capacity for both galena and pyrite, resulting in similar floatability and difficulty in effective separation. Currently, industrially, different types of depressants are often added to inhibit pyrite flotation, thereby achieving flotation separation of galena and pyrite. While the commonly used high-alkali lime method can inhibit pyrite, it reduces the recovery rate of galena, and the high pH environment easily leads to mud formation, affecting the flotation effect. Environmentally friendly depressants (such as organic colloids and polysaccharides) have unstable inhibitory effects. In summary, because galena and pyrite have similar surface hydrophobicity, conventional reagents are difficult to differentiate for adsorption. Furthermore, pyrite is easily oxidized, forming a Fe(OH)3 hydrophilic film, and the degree of oxidation is difficult to control precisely; excessive oxidation will affect the flotation of galena. Summary of the Invention

[0004] To address the shortcomings of the existing technology, this invention provides a flotation separation method for galena and pyrite. Specifically, the method involves: crushing, mixing, and preparing the slurry of galena and pyrite; adjusting the pH to 6.5-7.5 to obtain a pulp; first adding a complexing agent to the pulp for further preparation; then adding a combined collector for further preparation; finally adding a frother for further preparation; and finally performing flotation after preparation to obtain concentrate and tailings. The complexing agent is selected from EDTA-2Na; the combined collector consists of 3418A and [structure not specified]. The compound is composed of thiourea compounds, wherein R is selected from vinyl, allyl or ethyl; through the synergistic effect of complexing agents and combined collectors, it is suitable for the flotation separation of lead-iron sulfide minerals under neutral pH conditions, thereby achieving efficient separation of galena and pyrite, and the flotation under neutral pH conditions is environmentally friendly.

[0005] Based on the above technical objectives, the present invention adopts the following technical solution: This invention protects a flotation separation method for galena and pyrite, characterized by comprising the following steps: Galena and pyrite are crushed, mixed, and slurryed. The pH is then adjusted to 6.5-7.5 using hydrochloric acid or sodium hydroxide solution to obtain the slurry. In existing lead-iron separation processes, most methods use large amounts of lime to suppress gangue minerals, which raises the pH and damages the slurry and the environment. The most significant feature of the method in this invention is that flotation separation is performed under neutral pH conditions and without lime.

[0006] First, a complexing agent is added to the slurry to condition it; then, a combined collector is added to condition it; finally, a frother is added to condition it. After the slurry is conditioned, flotation is carried out to make galena float to the surface, thereby achieving the flotation separation of galena and pyrite, and obtaining concentrate and tailings respectively.

[0007] The mass ratio of complexing agent, combined collector and foaming agent is 60~180:10:5.

[0008] The complexing agent is selected from EDTA-2Na.

[0009] The combined collector consists of 3418A and has the following structural formula: The composition is a thiourea compound, wherein R is selected from vinyl, allyl or ethyl; the mass ratio of 3418A to the thiourea compound is 1:1~3.

[0010] Furthermore, the mass ratio of complexing agent, combined collector and frother is 140:10:5, which can achieve a galena recovery rate of more than 85%.

[0011] Preferably, the frother is selected from methyl isobutyl methanol. In the prior art, methyl isobutyl methanol is generally used as the frother for flotation separation of galena and pyrite.

[0012] Preferably, the particle size of galena and pyrite in the slurry is -0.074mm ± 0.038mm. In the experiment, a particle size of 200-400 mesh was selected for flotation because this particle size has sufficient monomer liberation (avoiding intergrowth), suitable specific surface area (ensuring effective adsorption of composite reagents and controlling costs), optimal particle-bubble interaction (high probability of collision and adhesion, stable mineralization), minimizes the impact of harmful slime (avoiding entrainment, capping, consumption of composite reagents, and foam deterioration), and controls grinding energy consumption costs (this particle size is the most commonly used for economically feasible mineral energy consumption costs).

[0013] Preferably, the total amount of complexing agent, combined collector and frother to slurry volume ratio is 35mg~195mg / L.

[0014] Preferably, the slurry is prepared for 1 to 3 minutes after adding the complexing agent, 1 to 3 minutes after adding the combined collector, and 1 minute after adding the foaming agent.

[0015] Preferably, the flotation time is 3 to 6 minutes, where the flotation time is the time after the slurry is prepared and the concentrate is removed from the scraper.

[0016] Compared with the prior art, the present invention has the following significant advantages: 1. This invention uses Aerophine 3418A (3418A) in combination with a thiourea compound as a combined collector, disodium ethylenediaminetetraacetate (EDTA-2Na) as a metal ion complexing agent, and methyl isobutyl methanol (MIBC) as a frother. During the flotation separation of galena and pyrite, 3418A and the thiourea compound exhibit a synergistic effect. After the galena is crushed, Pb is exposed on its surface. 2± Ion, 3418A dithiophosphonic acid anion [(RO)2PSS] - The terminal sulfur atom in galena exhibits strong nucleophilicity and electron-donating ability; this sulfur atom interacts with the Pb atoms on the galena surface. 2± Ions undergo chemical reactions; the core functional groups of thiourea compounds (such as ethylene thiourea) are thiocarbonyl (C=S) and amino (-NH-), which provide hydrophobicity and enable bubble mineralization; this dual mechanism makes it highly selective and environmentally adaptable in the flotation of complex sulfide ores, especially suitable for acidic pulps or in situations where copper and lead need to be preferentially floated. The main reason why this combination of collectors can achieve flotation under neutral pH conditions is that 3418A and thiourea compounds only have a collecting effect on pyrite under acidic conditions, but the collecting effect on galena is better under neutral conditions. Under alkaline or strongly alkaline conditions, the collecting effect of this combination of collectors on both is relatively poor. However, under neutral conditions, pyrite and galena will undergo galvanic corrosion. The iron ions dissolved in pyrite will inhibit the flotation of galena. At this time, the addition of the complexing agent EDTA-2Na solves this inhibition effect. EDTA-2Na will complex the iron ions in the pulp, thereby enabling the combination of collectors to act on galena and separate the two by flotation.

[0017] 2. This invention performs flotation under natural pH conditions. The combined collector used has a good collecting effect on galena. After adding a complexing agent, galena and pyrite can be separated by flotation in the mixed concentrate. The flotation separation method of this invention has a reasonable process structure, which can achieve a flotation recovery rate of over 85% for galena and a flotation recovery rate of less than 10% for pyrite, thereby achieving efficient separation of the two minerals.

[0018] 3. In the thiourea compound of the present invention, R is selected from alkenyl (-CH=CH2), allyl (-CH2-CH=CH2) or ethyl (-CH2-CH3). The vinyl, allyl or ethyl groups at the substitution position of R have stronger hydrophobicity than thiourea (R is -H) collectors. When combined with 3418A, they are more easily adsorbed on the mineral surface to form a hydrophobic film and have stronger collecting ability.

[0019] 4. This invention employs a novel composite reagent using EDTA-2Na complexing agent in conjunction with a combination of 3418A and thiourea compounds as collectors. This reagent can effectively inhibit pyrite within the natural pH range (6.5-7.5). Compared with the traditional high-alkali (pH>10) flotation process, it achieves lime-free flotation and effectively improves the pulp flotation conditions.

[0020] 5. During the flotation separation process, Fe is released from the dissolved pyrite surface. 2+ / Fe 3+ The ions form a hydrophilic film on the galena surface, inhibiting the adsorption of the combined collectors. The complexing agent EDTA-2Na effectively binds to these Fe atoms. 2+ / Fe 3+ Ion complexation provides sufficient adsorption sites for combined collectors on the galena surface, a mechanism that facilitates selective flotation separation between galena and pyrite. Attached Figure Description

[0021] Figure 1 This is a flowchart illustrating the flotation separation process of galena and pyrite according to the present invention.

[0022] Figure 2 The graph shows the recovery rate and grade data of the composite reagent for flotation of galena and pyrite under neutral pH conditions in Example 1. Detailed Implementation

[0023] To clearly illustrate the objectives, technical solutions, and advantages of the embodiments of the present invention, the technical solutions in this embodiment will be comprehensively and thoroughly described below with reference to the accompanying illustrations. It should be noted that the embodiments shown and described represent only a portion of the embodiments of the present invention, and not all of them. Generally, the layout and design of the components in the illustrations of the embodiments of the present invention can be adjusted according to various different configurations.

[0024] Considering the problems of existing conventional reagents being "difficult to differentiate adsorption" and "pyrite being easily oxidized, forming a Fe(OH)3 hydrophilic film, making it difficult to precisely control the degree of oxidation, and excessive oxidation affecting galena flotation," this invention provides a novel composite reagent. The composite reagent consists of a complexing agent, a combined collector, and a frother. The complexing agent is selected from EDTA-2Na, and the combined collector is composed of 3418A and [structure with the following formula]: Composed of thiourea compounds and with frother selected from methyl isobutyl methanol, this composite reagent not only achieves efficient flotation separation of galena and pyrite, solving the problem of "difficulty in differentiated adsorption", but also enables flotation separation under neutral pH conditions, overcoming the defects of "forming a Fe(OH)3 hydrophilic film, difficulty in accurately controlling the degree of oxidation, and excessive oxidation affecting galena flotation".

[0025] Figure 1 This is a schematic diagram of the flotation separation process of galena and pyrite provided by the present invention. As can be seen from the figure, the flotation separation of galena and pyrite is effectively achieved by using the composite flotation reagent of the present invention under neutral pH conditions.

[0026] Taking pyrite and galena as examples, the separation effect of the present invention is illustrated. The mineral composition is shown in Table 1. Table 1. Original Grades and Origins of Pyrite and Galena The technical solution of the present invention will be studied below using examples and comparative examples. The specific research methods and results are shown below: Example 1 A flotation separation method for galena and pyrite includes the following steps: S1. After grinding galena and pyrite to a particle size of 0.074mm±0.038mm, they are artificially mixed, the pH is adjusted to 7.0 with hydrochloric acid solution, and the mixture is stirred for 3 minutes to obtain the slurry.

[0027] S2. First, add the complexing agent EDTA-2Na to the slurry at a concentration of 60 mg / L, and stir for 3 minutes to adjust the slurry consistency; then add the combined collector 3418A and ethylene thiourea (ETU). (It is a vinyl-substituted thiourea compound), the mass ratio of 3418A to vinyl thiourea is 1:1, the combined collector dosage is 10 mg / L, and the mixture is stirred and prepared for 3 min; finally, the foaming agent MIBC is added, the dosage of foaming agent MIBC is 5 mg / L, and the mixture is stirred and prepared for 1 min.

[0028] S3. After the slurry conditioning is completed, perform flotation for 3 minutes.

[0029] Example 2 A flotation separation method for galena and pyrite is the same as the preparation steps in Example 1, except that the amount of complexing agent EDTA-2Na is replaced from 60 mg / L to 100 mg / L.

[0030] Example 3 A flotation separation method for galena and pyrite is the same as the preparation steps in Example 1, except that the amount of complexing agent EDTA-2Na is replaced from 60 mg / L to 140 mg / L.

[0031] Example 4 A flotation separation method for galena and pyrite is the same as the preparation steps in Example 1, except that the amount of complexing agent EDTA-2Na is replaced from 60 mg / L to 180 mg / L.

[0032] Example 5 A flotation separation method for galena and pyrite includes the following steps: S1. After grinding galena and pyrite to a particle size of 0.074mm±0.038mm, they are artificially mixed, and the pH is adjusted to 6.5 with hydrochloric acid solution. The mixture is stirred for 4 minutes to obtain the slurry.

[0033] S2. Add complexing agent EDTA-2Na to the slurry at a concentration of 140 mg / L, and stir for 2 minutes; then add combined collector 3418A and allyl thiourea ( (It is an allyl-substituted thiourea compound), the mass ratio of 3418A to allyl thiourea is 1:2, the combined collector dosage is 10 mg / L, and the mixture is stirred and slurryed for 2 min; finally, the foaming agent MIBC is added, the dosage of foaming agent MIBC is 5 mg / L, and the mixture is stirred and slurryed for 1 min.

[0034] S3. After the slurry conditioning is completed, perform flotation for 5 minutes.

[0035] Example 6 A flotation separation method for galena and pyrite includes the following steps: S1. After grinding galena and pyrite to a particle size of 0.074mm±0.038mm, they are artificially mixed, the pH is adjusted to 7.5 with sodium hydroxide solution, and the mixture is stirred for 3 minutes to obtain the slurry.

[0036] S2. First, add the complexing agent EDTA-2Na to the slurry. The dosage of EDTA-2Na is 140 mg / L. Stir and adjust the slurry for 1 min. Then, add the combined collector 3418A and ethylthiourea ( (It is an ethyl-substituted thiourea compound), the mass ratio of 3418A to ethyl thiourea is 1:3, the combined collector dosage is 10 mg / L, and the mixture is stirred and slurryed for 1 min; finally, the foaming agent MIBC is added, the foaming agent MIBC dosage is 5 mg / L, and the mixture is stirred and slurryed for 1 min.

[0037] S3. After the slurry conditioning is completed, perform flotation for 6 minutes.

[0038] Comparative Example 1 A flotation separation method for galena and pyrite is the same as the preparation steps in Example 1, except that the amount of complexing agent EDTA-2Na is replaced from 60 mg / L to 20 mg / L.

[0039] Examples 1 to 6 of this invention all yielded composite flotation reagents for galena and pyrite with excellent flotation performance under neutral pH conditions. The following research uses the composite flotation reagents for galena and pyrite under neutral pH conditions from Examples 1 to 4 as examples. Specific research methods and results are shown below: Table 2. Flotation separation results of different amounts of EDTA-2Na under natural pH conditions. from Figure 2 As shown in Table 2, with increasing EDTA-2Na dosage, both the PbS concentrate grade and recovery rate exhibited a "first increase, then decrease" trend, with the grade remaining above 90%. Specifically, the PbS recovery rate was lowest (15.58%) when the EDTA-2Na dosage was 20 mg / L, and highest (87.98%) when the dosage was 140 mg / L. The mechanism can be summarized as follows: under natural pH conditions, Fe2+ dissolves and releases Fe2+ from the FeS2 surface. 2+ / Fe 3+ A hydrophilic film will form on the PbS surface, blocking the interfacial interaction between the combined collector (3418A and ETU) and PbS, thus inhibiting PbS flotation. After adding EDTA-2Na, its strong complexing effect preferentially binds to Fe. 2+ / Fe 3+ This combination provides ample adsorption sites for the collector on the PbS surface. Simultaneously, the PbS surface... 2+ The complexation ability with EDTA-2Na is weak, and the combined collector exhibits high selectivity for PbS, thus PbS retains good hydrophobicity. When the dosage of EDTA-2Na increases to 180 mg / L, both the PbS grade and recovery rate decrease, because excess EDTA-2Na preferentially complexes Fe. 2+ / Fe 3+ Subsequently, it will further complex Pb on the PbS surface. 2+ This affects the adsorption of the collector. In summary, under neutral pH conditions, when the combined collector dosage of 3418A and ETU is 10 mg / L and the dosage of EDTA-2NA is 140 mg / L, efficient flotation separation of PbS and FeS2 can be achieved.

[0040] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A flotation separation method for galena and pyrite, characterized in that, Includes the following steps: Galena and pyrite are crushed, mixed, and slurryed, and then the pH is adjusted to 6.5-7.5 to obtain the slurry. First, a complexing agent is added to the slurry to condition it; then, a combined collector is added and the slurry is conditioned; finally, a frother is added and the slurry is conditioned; after the slurry conditioning is completed, flotation is carried out to obtain concentrate and tailings respectively. The mass ratio of complexing agent, combined collector and foaming agent is 60~180:10:5; The complexing agent is selected from EDTA-2Na; The combined collector consists of 3418A and has the following structural formula: The composition is a thiourea compound, wherein R is selected from vinyl, allyl or ethyl; the mass ratio of 3418A to the thiourea compound is 1:1~3.

2. The flotation separation method for galena and pyrite according to claim 1, characterized in that, The mass ratio of complexing agent, combined collector and foaming agent is 140:10:

5.

3. The flotation separation method for galena and pyrite according to claim 1, characterized in that, The foaming agent is selected from methyl isobutyl alcohol.

4. The flotation separation method for galena and pyrite according to claim 1, characterized in that, In the slurry, the particle size of both galena and pyrite was 0.074 mm ± 0.038 mm.

5. The flotation separation method for galena and pyrite according to claim 1, characterized in that, The total amount of complexing agent, combined collector and frother to the volume ratio of slurry is 35mg~195mg / L.

6. The flotation separation method for galena and pyrite according to claim 1, characterized in that, After adding the complexing agent, adjust the slurry for 1 to 3 minutes.

7. The flotation separation method for galena and pyrite according to claim 1, characterized in that, After adding the combined collector, adjust the slurry for 1 to 3 minutes.

8. The flotation separation method for galena and pyrite according to claim 1, characterized in that, After adding the foaming agent, adjust the slurry for 1 minute.

9. The flotation separation method for galena and pyrite according to claim 1, characterized in that, The flotation time is 3 to 6 minutes.

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