Flotation separation process for galena and pyrite

Description

2 Content of the invention As a remedy to the shortcomings of the prior art, the present invention proposes a process for separating galena and pyrite by flotation. More precisely, the process consists of crushing galena and pyrite, mixing them and putting them into a pulp, then adjusting the pH to 6.5–7.5 in order to obtain a mineral pulp; first adding a complexing agent to the pulp and proceeding with conditioning; then adding a composite collector and proceeding with conditioning; finally adding a foaming agent and proceeding with conditioning; After completion of conditioning, a flotation operation is carried out to obtain a concentrate and waste products, respectively. The complexing agent is chosen from EDTA-2Na; the composite collector is composed of 3418A and a thiourea compound with structural formula 10, in which the vinyl group, the allyl group, or the ethyl group is chosen. Thanks to the synergistic action of the complexing agent and the composite collector,The process is applicable to the separation by flotation of lead and iron sulfide minerals under conditions of pH neutral, thus allowing an efficient separation of galena and pyrite; moreover, flotation carried out at pH neutral is environmentally friendly. Based on the above technical objective, the present invention adopts the following technical solution: The present invention protects a process for separating galena and pyrite by flotation, characterized in that it comprises the following steps: 20 Crushing the galena and pyrite, mixing them and pulping them, then adjusting the pH to 6.5–7.5 by means of a hydrochloric acid solution or a sodium hydroxide solution in order to obtain a mineral pulp; in existing processes for separating lead and iron, a large quantity of lime is generally used to inhibit the gangue minerals, which leads to an increase in pH and causes damage to both the pulp and the environment, 25Whereas the principal characteristic of the process of the present invention lies in carrying out the separation by flotation at pH neutral and without the use of lime; First, add a complexing agent to the pulp and proceed to conditioning; then add a composite collector and proceed to conditioning; finally, add a foaming agent and proceed to conditioning; after completion of conditioning, carry out a flotation operation to make the galena float, thus carrying out the separation by flotation of the galena and the pyrite, and obtain respectively a concentrate and the rejects. In which the mass ratio between the complexing agent, the composite collector and the foaming agent is 60–180:10:5. BE2026 / 7261 3 The complexing agent is chosen from EDTA-2Na. The composite collector is made of 3418A and a thiourea compound of structural formula, in which the vinyl group, the allyl group, or the ethyl group is chosen; the mass ratio between 3418A and the thiourea compound is 1:1–3.5. More advantageously,The mass ratio between the complexing agent, the composite collector, and the foaming agent is 140:10:5, this ratio allowing a galena recovery rate greater than 85%. Preferably, the foaming agent is chosen from methyl-isobutyl-carbinol; in the prior art, methyl-isobutyl-carbinol is generally used as a foaming agent for the flotation separation of galena and pyrite. Preferably, in the mineral pulp, the particle size distribution of galena and pyrite is −0.074 mm ± 0.038 mm. During testing, a particle size fraction of 200 to 400 meshes is chosen for flotation, as it presents a sufficient degree of monomer release (avoiding composite particles), a suitable specific surface area (ensuring efficient adsorption of composite reagents while controlling costs), optimal particle-bubble interaction (high probability of collision and adhesion, stable mineralization), and minimization of the detrimental influence of fine sludge (avoiding entrainment, over-coverage,Excessive consumption of reagents and foam degradation), as well as control of the energy consumption of grinding (which makes it an economically viable particle size commonly used). Preferably, the ratio between the total quantity of complexing agent, composite collector, and foaming agent and the volume of mineral pulp is 35 mg to 195 mg / L. Preferably, after the addition of the complexing agent, conditioning is carried out for 1 to 3 min; after the addition of the composite collector, conditioning is carried out for 1 to 25 min; and after the addition of the foaming agent, conditioning is carried out for 1 min. Preferably, the flotation time is 3 to 6 min, the flotation time corresponding to the time elapsed after the end of conditioning until the detachment of the concentrate on the scraper. Compared to the prior art, the present invention has the following significant advantages30: 1. The present invention uses Aerophine 3418A (3418A) in combination with a thiourea compound as a composite collector,Disodium ethylenediaminetetraacetate (EDTA-2Na) as a complexing agent for metal ions, and methyl isobutylcarbinol BE2026 / 7261 4 (MIBC) as a foaming agent. During the flotation separation of galena and pyrite, a mutual promotion action occurs between 3418A and the thiourea compound. After crushing galena, Pb²⁺ ions are exposed on its surface; the terminal sulfur atom of the dithiophosphinate[(RO)2PSS]- anion of 3418A exhibits strong cleophilicity and a high electron-donating capacity, and the sulfur atom reacts chemically with the 5 Pb²⁺ ions present on the surface of galena. The key functional group of thiourea compounds (such as vinyl thiourea) is composed of a thiocarbonyl group (C=S) and an amine group (-NH-), conferring hydrophobicity that allows for the mineralization of bubbles. This dual mechanism of action gives the compound high selectivity and good environmental adaptability in the flotation of complex sulfide minerals.being10 particularly suited to acidic pulps or cases requiring priority flotation of copper or lead. The main reason why this composite collector allows flotation under pH-neutral conditions is the following: 3418A and thiourea compounds exert a collecting action on pyrite mainly in acidic media, while their collecting effect on galena is relatively better in another medium; in a strongly alkaline or15 alkaline medium, the collecting effect of the composite collector on both minerals is weak. However, under neutral pH conditions, galvanic corrosion occurs between pyrite and galena; the iron ions dissolved in the pyrite inhibit the flotation of galena. The addition of the complexing agent EDTA-2Naper metalors eliminates this inhibitory effect, as EDTA-2Na complexes the iron ions present in the pulp, so that the action of the composite collector 20 is exerted preferentially on galena.2. The present invention achieves flotation under natural pH conditions; the composite collector used exhibits good collection capacity with respect to galena, and the addition of the complexing agent allows galena and pyrite to be separated by flotation from a mixed concentrate. The flotation separation process of the present invention has a rational process structure, allowing a galena recovery rate greater than 85%, while the pyrite recovery rate is less than 10%, thus achieving an efficient separation of the two minerals. 3. In the thiourea compound of the present invention, the substitute R is chosen from among 30 an alkenyl group (-CH=CH₂), an allyl group (-CH₂-CH=CH₂) or an ethyl group (-CH₂-CH₃). Compared to unsubstituted thiourea collectors (R=-H), thioureas substituted with vinyl, allyl or ethyl groups exhibit higher hydrophobicity,They adsorb more easily in combination with 3418A on the surface of minerals to form a hydrophobic film, and possess an enhanced collecting capacity. 35 4. The present invention uses a novel composite reagent combining the complexing agent EDTA-2Na and the composite collector made up of 3418A and a thiourea compound. In the BE2026 / 7261 5 natural pH range (6.5–7.5), this reagent allows effective inhibition of pyrite. Compared to traditional flotation processes at high alkalinity (pH > 10), the present invention achieves flotation without the use of lime, effectively improving the flotation conditions of the pulp. 5. During the flotation separation process, the Fe²⁺ / Fe³⁺ ions released by dissolution 5 on the surface of the pyrite form a hydrophilic film on the surface of the galena, inhibiting the adsorption of the composite collector. The complexing agent EDTA-2 Nase effectively complexes with these Fe²⁺ / Fe³⁺ ions,It thus provides sufficient adsorption sites for the composite collector on the surface of the galena. This mechanism promotes selective separation by flotation between the galena and the pyrite. 10 Description of the figures Fig. 1 illustrates the schematic process for the separation by flotation of the galena and the pyrite according to the present invention. Fig. 2 illustrates the recovery rate and active residue content data for the composite flotation of the galena and the pyrite under pH-neutral conditions according to Example 1. Concrete embodiment In order to clearly set forth the objectives, technical solutions, and advantages of the embodiments of the present invention, the technical solutions of the examples are described in full and detail below in combination with the accompanying figures. It should be specified that the examples described and illustrated represent only a part of the embodiments of the present invention and not all of them. In general,The arrangement and design of the components of the exemplary embodiments of the present invention, as shown in the figures, can be adjusted according to various configurations. 25 In view of the prior art problems according to which conventional reagents "have difficulty adsorbing in a differentiated manner" and according to which "pyrite is easily oxidized, forming a hydrophilic film of Fe(OH)₃, the degree of oxidation of which is difficult to control precisely, excessive oxidation affecting the flotation of galena," the present invention proposes a completely new composite reagent. The composite reagent is 30 composed of a complexing agent, a composite collector, and a foaming agent; the complexing agent is chosen from EDTA-2Na, the composite collector is composed of 3418A and a composed of thiourea with a structural formula, and the foaming agent is chosen from methyl-isobutyl-carbinol. This composite reagent only allows for an efficient flotation separation of galena and pyrite. BE2026 / 7261 6resolving the problem of "differentiated adsorption difficulty," but also enabling flotation under neutral pH conditions, thus overcoming the drawbacks related to "the formation of a hydrophilic Fe(OH)₃ film, imprecise control of the degree of oxidation, and the negative impact of excessive oxidation on galena flotation."5 Fig. 1 illustrates the schematic process for separating galena and pyrite by flotation according to the present invention. As shown in the figure, the use of the composite flotation reagent for galena and pyrite under neutral pH conditions according to the present invention makes it possible to efficiently separate galena and pyrite by flotation. For example,The separation effect of the present invention is illustrated using 10 single-component minerals of pyrite and galena. The composition of the minerals is presented in Table 1. Table 1 Initial content and origin of pyrite and galena Mineral name PbFeS Origin Galena 83.77 / 14.33 Hunan Pyrite / 46.0451.64 Hubei The technical solutions of the present invention are studied below by means of 15 examples of implementation and comparative examples, the specific methods and results being described as follows. Example 1 A process for the flotation separation of galena and pyrite, comprising the following steps: of hydrochloric acid, and the pulp is conditioned by stirring for 3 minutes to obtain a mineral pulp. S2.A complexing agentEDTA-2Na is first added to the mineral pulp, at a rate of 6025 mg / L,The pulp is then conditioned by agitation for 3 minutes; a composite collector consisting of 3418A and vinyl thiourea (ETU, a thiourea compound substituted with a vinyl group) is then added, the mass ratio between 3418A and ETU being 1:1, the quantity of the composite collector being 10 mg / L, followed by conditioning by agitation for 3 minutes; finally, a foaming agent MIBC is added at a rate of 5 mg / L, followed by conditioning by agitation for 1 minute. BE2026 / 7261 7 S3. After completion of conditioning, flotation is carried out for 3 minutes. Example 2 A flotation separation process for galena and pyrite, identical to that of Example 1, except that the quantity of EDTA-2Na is changed from 60 mg / L to 100 mg / L. Example 3 A flotation separation process for galena and pyrite, identical to that of Example 1, except that the quantity of EDTA-2Na is changed from 60 mg / L to 140 mg / L. Example 4 A flotation separation process for galena and pyrite, identical to that of Example 1,except that the quantity of EDTA-2 is modified from 60mg / L to 180 mg / L. Example 5 A flotation separation process for galena and pyrite, comprising the following steps 15: S1. Galena and pyrite are ground separately to a particle size of 0.074 mm ±0.038 mm, then artificially mixed; the pH is adjusted to 6.5 by means of a hydrochloric acid solution, and the pulp is conditioned by agitation for 4 minutes to obtain a mineral pulp. S2. A complexing agent, EDTA-2Na, is added to the mineral pulp at a rate of 140 mg / L, then conditioned by agitation for 2 minutes; a composite collector consisting of 3418A and allyl thiourea (a thiourea compound substituted with an allyl group) is then added, the mass ratio between 3418A and allyl thiourea being 1:2, the The quantity of composite collector being 10 mg / L, followed by conditioning by agitation for 2 minutes; finally, a foaming agent MIBC is added at a rate of 5 mg / L, followed by conditioning by agitation for 1 minute. S3. After completion of conditioning,A flotation is carried out for 5 min. Example 6 A process for the separation by flotation of galena and pyrite, comprising the following steps 30: S1. Galena and pyrite are ground separately to a particle size of 0.074 mm ±0.038 mm, then artificially mixed; the pH is adjusted to 7.5 by means of a sodium hydroxide solution, and the pulp is conditioned by agitation for 3 min in order to obtain BE2026 / 7261 8 a mineral pulp. S2. A complexing agent, EDTA-2Na, is first added to the mineral pulp at a rate of 140 mg / L, then conditioned by agitation for 1 min; a composite collector consisting of 3418A and ethyl thiourea (a thiourea compound substituted with an ethyl group) is then added, the mass ratio between 3418A and ethyl thiourea being 5:3, the quantity of the composite collector being 10 mg / L, followed by conditioning by agitation for 1 min; finally, a foaming agent, MIBC, is added at a rate of 5 mg / L, followed by conditioning by agitation for 1 min. S3. After completion of conditioning,A flotation is carried out for 6 minutes. Comparative Example 110: A flotation separation process for galena and pyrite, identical to that of Example 1, except that the quantity of EDTA-2Na is modified from 60 mg / L to 20 mg / L. Examples 1 to 6 of the present invention all allow obtaining a composite flotation reagent for galena and pyrite exhibiting excellent flotation performance under neutral pH conditions. Examples 1 to 4 are taken by way of illustration to analyze the performance of the composite flotation reagent under natural pH conditions.The specific methods and results are presented below. Table 2 Results of flotation separation for different quantities of EDTA-2Na under natural pH conditions 20 Sample Product Yield (%) Content (%) Recovery (%) PbFe PbFe Comparative Example 1 Concentrate 8.59 78.54 4.33 15.58 1.60 Rejects 91.41 39.99 25.12 84.43 98.40 Total 100.00 43.31 23.33 100.00 100.00 Example 1 Concentrate 14.28 80.34 3.37 26.49 2.06 Rejects 85.72 37.14 26.66 73.51 97.94 Total 100.00 43.31 23.33 100.00 100.00 Example 2 Concentrate 37.92 81.60 2.69 71.45 4.38 Discharges 62.08 19.92 35.94 28.55 95.62 Total 100.00 43.31 23.33 100.00 100.00 Example 3 Concentrate 46.34 82.22 2.35 87.98 4.69 Discharges 33.66 15.48 66.08 12.02 95.31 Total 100.00 43.31 23.33 100.00 100.00 BE2026 / 7261 9 Example 4 Concentrate 44.28 79.28 3.94 81.06 7.49 Discharges 55.72 14.73 38.74 18.94 92.51 Total100.0043.3123.33100.00100.00 As shown,