A method for improving the quality of high-zinc iron concentrate and reducing silicon to prepare high-purity iron concentrate

Abstract

The invention discloses a method for preparing high-purity iron concentrate by improving the quality of high-zinc iron concentrate and reducing silicon. The method performs pulping and re-grinding treatment on the high-zinc iron concentrate to obtain re-grinded slurry; the re-grinded slurry is subjected to reverse flotation, the flotation concentrate is zinc concentrate, the flotation tailings are iron concentrate, and the flotation tailings are subjected to magnetic separation to obtain high-purity iron concentrate and high-silicon tailings. The high-purity iron concentrate obtained by the method has TFe>70%, Zn<0.05%, SiO2<0.3%, and the iron loss rate does not exceed 3%. The method is highly operable and has strong adaptability to raw materials. The tailings obtained by flotation do not need to be concentrated and re-grinded, and can be directly put into magnetic separation operation for deep impurity removal to obtain high-purity iron concentrate, saving energy consumption and water. The obtained iron concentrate can meet the original requirements of major steel companies for producing high-purity special steel, and solves the problems of poor dezincification effect of high-zinc iron concentrate, high energy consumption and poor indicators in the production of high-purity iron concentrate.

Description

Technical Field

[0001] The invention relates to a method for preparing high-purity iron concentrate, in particular to a method for preparing high-purity iron concentrate by improving the quality of high-zinc iron concentrate and reducing silicon, and belongs to the technical field of mineral processing. Background Art

[0002] At present, due to the high zinc content (>0.1%) in some iron concentrates, they cannot be used directly as raw materials for the furnace. This is because the reduction temperature of zinc and the boiling point of liquid zinc are low, and it can hardly be absorbed by slag iron during the blast furnace ironmaking process, which will have an adverse effect on the subsequent blast furnace smelting process. Therefore, in order to ensure the smooth progress of the ironmaking blast furnace, it is necessary to reduce the zinc content of the iron concentrate as much as possible; in addition, the current super iron concentrate is an important source of raw materials for the development of high-end steel, in which the content of harmful impurities such as SiO2, S, and P is extremely low, and can be used to produce direct reduced iron, powder metallurgy, magnetic materials, ultra-pure iron and clean steel base materials. The development of high-end steel using high-purity super iron concentrate as raw material has many advantages such as low resource and energy consumption, low pollution emissions, high product quality and stable performance. The market demand for high-purity iron concentrate is large and the added value is high. Therefore, if the preparation of super iron concentrate can be achieved, it will solve the problem of high-quality raw material sources for the development of high-end steel in my country.

[0003] The harmful impurity zinc in iron concentrate generally exists in the form of sphalerite and zinc-iron spinel. It is difficult to achieve deep removal of zinc by a single means. Sphalerite and iron sphalerite often show poor flotation and are sensitive to the medium, and their floatability is much less than other sulfides. Therefore, it is very difficult to flotate sphalerite and iron sphalerite without activation. Especially when zinc exists in the form of zinc-iron spinel, it is more difficult to remove. It is formed by zinc atoms replacing iron atoms in the magnetite lattice in an isomorphous form. This type of mineral enters the interior of magnetite and coexists with magnetite, and it is very easy to enter the magnetic concentrate product through a single magnetic separation.

[0004] Chinese patent CN113477405B discloses a preparation method of a sphalerite and sphalerite beneficiation activator and a flotation zinc reduction method; amino acids containing multiple ligands are preferably used as activators to increase the depth of zinc removal. Although the depth of zinc removal in iron concentrate can be achieved, there are also strict requirements on the zinc grade (<0.1%), which is not applicable to high-zinc iron concentrate; Chinese patents CN114289175A and CN112495573B respectively disclose a method for improving the quality of low-grade iron concentrate. The silicon reduction reselection process and a method for high-value utilization of ordinary high-silicon iron concentrate are only suitable for improving the quality and reducing impurities of high-silicon iron concentrate, and the process is long and complicated. In addition, when preparing ultra-pure iron concentrate, impurities and raw ore that is over-ground into dust will be accompanied during the stage grinding, resulting in a large load during the subsequent fine-grained magnetic separation, and too many impurities are mixed in the fine flow iron concentrate after magnetic separation. Traditional hydrometallurgical dezincification requires a large amount of water, which is not only too expensive and the process is relatively complicated, but also easy to produce wastewater and cause environmental pollution. At present, no effective technology for improving the quality and removing impurities to prepare high-purity iron concentrate for high-zinc iron concentrate (Zn>0.3%) has been found. Summary of the invention

[0005] In the existing actual production process, high-zinc iron concentrate must be combined with multiple separation means to improve the quality of the iron concentrate and reduce impurities to prepare qualified high-purity iron concentrate. The purpose of the present invention is to provide a beneficiation method for obtaining high-purity iron concentrate by removing zinc and silicon from high-zinc iron concentrate. The method obtains ultra-pure iron concentrate with TFe>70%, Zn<0.05%, and SiO2<0.3% through a combination of regrinding, flotation dezincification, and magnetic separation desludging of high-zinc iron concentrate, and the iron recovery rate is high, the loss rate does not exceed 3%, the process flow is highly adaptable, and it is easy to scale up production.

[0006] In order to achieve the above technical objectives, the present invention provides a method for improving the quality of high-zinc iron concentrate and reducing silicon to prepare high-purity iron concentrate, the method is to slurry the high-zinc iron concentrate and regrind it to obtain reground slurry; the reground slurry is reverse flotation, the flotation concentrate is zinc concentrate, the flotation tailings is iron concentrate, and the flotation tailings are magnetically separated to obtain high-purity iron concentrate and high-silicon tailings.

[0007] In view of the characteristics that zinc impurities in high-zinc iron concentrate are mainly present in the form of zinc minerals such as sphalerite and sphalerite, while iron is mainly present in the form of magnetite, the present invention subjects the high-zinc iron concentrate to regrinding treatment to achieve stripping of sphalerite and sphalerite, etc., but since a small amount of zinc atoms replace iron atoms in the magnetite lattice in an isomorphous form to form zinc-iron spinel, it is difficult to separate the zinc-iron spinel from the magnetite by a conventional magnetic separation method, so the sphalerite, sphalerite zinc and the iron spinel are efficiently pre-separated by activation and reverse flotation means, and the magnetite can be separated from the residual silicon impurities by combining with weak magnetic separation, so as to obtain a high-purity iron concentrate.

[0008] As a preferred solution, the particle size of the high-zinc iron concentrate satisfies the -200 mesh particle size content of more than 70%, and the iron grade is 58% to 66%, and the zinc content is more than 0.3%. The zinc content in the high-zinc iron concentrate is too high to be used directly as a raw material for the furnace, and the iron grade is relatively low and needs to be further improved to ensure the smooth operation of the iron-making blast furnace. At the same time, ultra-pure iron concentrate is an important source of raw materials for high-end steel, and can also be used to produce direct reduced iron, powder metallurgy, magnetic materials, ultra-pure iron and clean steel base materials. Therefore, it is very necessary to improve the quality of high-zinc iron concentrate.

[0009] As a preferred solution, the regrinding process grinds the high zinc iron ore to a particle size that satisfies the mass percentage content of the -200 mesh particle size of more than 90% (preferably more than 94%), and the mass percentage content of the -200 mesh to +400 mesh particle size is 40-45%. The regrinding process is the preferred particle size range, which can well achieve monomer dissociation. The grinding equipment can be a ball mill or a stirred mill, and the grinding concentration is 60-70%.

[0010] As a preferred solution, during the reverse flotation process, the pulp concentration is adjusted to 30-40 wt%, the pulp pH is adjusted to 3-5 (preferably 3-4), and the reverse flotation process is: one roughing selection + two cleaning selections + three scavenging selections.

[0011] As a preferred solution, in the roughing process, at least one of ammonium chloride, ammonium carbonate, citric acid and sodium citrate is used in combination with copper sulfate in a mass ratio of (0.5-3):1 as a combined activator, at least one of butylamine black medicine, n-dodecyl mercaptan and tert-dodecyl mercaptan is used in combination with xanthate in a mass ratio of 1:(1-10) (preferably 1:(1-5)) as a combined collector, and at least one of pine alcohol, methyl isobutyl carbinol, diethyl phthalate and diethylene glycol butyl ether is used as a frother. The preferred combined activator can fully activate sphalerite and sphalerite, improve the collection ability of the combined collector for zinc minerals, and the preferred combined collector can simultaneously and efficiently selectively capture sphalerite and sphalerite. Through the synergistic effect between the combined activator and the combined collector, the selectivity and collection performance of the flotation reagent for sphalerite and sphalerite are enhanced, the removal efficiency of zinc-containing minerals is improved, and the iron loss rate is reduced. More specifically, the xanthate collector contains C=S and the thiol collector contains SH. The two functional groups are adsorbed on the surface of the target mineral through molecular chelation, which produces a strong hydrophobic effect, which is stronger than the adsorption effect of a single collector system. Generally speaking, at a suitable ratio, the combined collector will comprehensively exert the synergistic effect of the two agents, improve the mineral recovery rate and reduce the total amount of collectors used. The addition of the combined activator promotes the formation of copper-ammonium complex ion complex or copper-citrate complex in the solution, so as to achieve the storage and controlled release of copper ions and maintain a high copper ion concentration in the solution. At the same time, ammonium ions and citric acid molecules can promote the dissolution of zinc hydroxide, a hydrophilic substance on the surface of sphalerite, and promote copper sulfate to generate hydrophobic species copper-sulfur compounds on the surface of the target mineral, increase the amount of copper adsorbed on the surface, and achieve the purpose of efficiently activating sphalerite.

[0012] As a preferred solution, the concentration of the combined activator added to the slurry during the roughing process is 400-1000 g / t, and the mass of the combined activator is measured by the mass of copper sulfate.

[0013] As a preferred solution, the combined collector is added to the ore pulp at a concentration of 100-300 g / t, and the mass of the combined collector is measured by the mass of the xanthate.

[0014] As a preferred solution, the concentration of the foaming agent added to the slurry is 15-50 g / t.

[0015] As a more preferred embodiment, the xanthate is at least one of butyl xanthate, isobutyl xanthate, amyl xanthate and isobutyl xanthate.

[0016] As a preferred embodiment, during the scanning process, at least one of ammonium chloride, ammonium carbonate, citric acid and sodium citrate is used as a combined activator in a mass ratio of (0.5-3):1 with copper sulfate in the first two scannings, at least one of butylamine black medicine, n-dodecyl mercaptan and tert-dodecyl mercaptan is used as a combined collector in a mass ratio of 1:(1-10) (preferably 1:(1-5)), and at least one of pineol, methyl isobutyl carbinol, diethyl phthalate and diethylene glycol butyl ether is used as a foaming agent; in the third scanning, a metal ion-hydroxamic acid complex is used as a collector; the metal ion in the metal ion-hydroxamic acid complex includes Pb 2+ , Ca 2+ Mg 2+ , Cu 2+ 、Al 2+ , Mn 2+ At least one of the hydroxamic acid ligands includes at least one of benzohydroxamic acid, octylhydroxamic acid, and salicylic hydroxamic acid, and the molar ratio of metal ions to hydroxamic acid ligands is 1:1-5 (preferably 1:1-3). After roughing, twice fine selection and twice scavenging under the preferred agent, most of sphalerite and sphalerite can be removed, and the remaining difficult to select is zinc-iron spinel in the form of lattice substitution. The present invention uses a metal ion-hydroxamic acid complex collector, which can activate and efficiently act on zinc-iron spinel, achieves efficient capture of the remaining difficult to select zinc-iron spinel, increases the zinc removal depth, and zinc can be reduced to below 0.05%, providing a strong guarantee for the subsequent magnetic separation to prepare high-purity iron concentrate.

[0017] As a preferred solution, the concentration of the combined activator added to the ore pulp during the first two sweeping processes is 200-500 g / t, and the mass of the combined activator is measured by the mass of copper sulfate; the concentration of the combined collector added to the ore pulp is 50-150 g / t, and the mass of the combined collector is measured by the mass of xanthate; the concentration of the frother added to the ore pulp is 7-25 g / t; the xanthate is at least one of butyl xanthate, isobutyl xanthate, amyl xanthate, and isobutyl xanthate.

[0018] As a preferred solution, the concentration of the metal ion-hydroxamic acid complex added to the ore pulp during the third scavenging process is 100-300 g / t (preferably 200-300 g / t).

[0019] As a preferred solution, the magnetic separation includes two weak magnetic separation processes. As a more preferred solution, the two weak magnetic separation processes both use permanent magnetic drum magnetic separators, and the magnetic field strength is 300-800 Gs (preferably 400-600 Gs). Based on the efficient removal of zinc minerals such as zinc-iron spinel with weak magnetic properties by reverse flotation, the separation of iron and silicon impurities can be achieved through the weak magnetic separation process, and even if there is a small amount of residual zinc-iron spinel and other liquids, it can be separated from magnetite by weak magnetic separation.

[0020] As a preferred solution, the rough selection time is 5 to 8 minutes.

[0021] As a preferred solution, the time for each selection and each scanning is 3 to 5 minutes.

[0022] As a preferred solution, the selection is blank selection without using flotation reagents.

[0023] The zinc content of the high-zinc iron concentrate of the present invention is greater than 0.3% by mass, for example, between 0.35 and 0.42%.

[0024] Compared with the prior art, the technical solution of the present invention brings the following beneficial technical effects:

[0025] (1) The technical solution of the present invention is aimed at the characteristics of high-zinc iron concentrate. High-purity iron concentrate is obtained by combining the process of regrinding, reverse flotation dezincification, magnetic separation and impurity removal on the high-zinc iron concentrate. The regrinding of the high-zinc iron concentrate realizes the monomer dissociation of zinc-containing minerals, the reverse flotation dezincification greatly reduces the zinc content, and the magnetic separation de-impurity further improves the iron grade in the iron concentrate, and finally a high-purity iron concentrate with TFe>70%, Zn<0.05%, and SiO2<0.3% is obtained.

[0026] (2) In the reverse flotation dezincification process of the technical solution of the present invention, the synergistic effect of the reagents is fully utilized. By adopting a special combination of activators and combined collectors, the selectivity and collection performance of the flotation reagents are enhanced at the same time, the removal efficiency of zinc-containing minerals represented by sphalerite and marmatite is improved, and the iron loss rate is reduced. At the same time, the metal-organic complex collector is used to achieve the efficient collection of the remaining difficult-to-select zinc-iron spinel in the form of lattice substitution, thereby increasing the zinc removal depth, and the zinc content can be reduced to below 0.05%, which provides a strong guarantee for the subsequent magnetic separation to prepare high-purity iron concentrate.

[0027] (3) In the technical solution of the present invention, the iron concentrate after zinc removal by reverse flotation can be used to prepare high-purity iron concentrate with TFe>70%, Zn<0.05%, and SiO2<0.3% through two weak magnetic separations. The desiliconization effect is significant and the production energy consumption is low.

[0028] (4) The method for improving the quality of high-zinc iron concentrate and reducing impurities to prepare high-purity iron concentrate according to the technical solution of the present invention has simple steps, strong operability, and strong adaptability to raw materials. The tailings obtained by flotation do not need to be concentrated and ground again, and can directly enter the magnetic separation operation for deep impurity removal to obtain high-purity iron concentrate, saving energy and water. The obtained iron concentrate can meet the original requirements of major steel companies for the production of high-purity special steel, and solves the current problems of poor dezincification effect of high-zinc iron concentrate, high energy consumption in the production of high-purity iron concentrate, and poor indicators. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Flow chart for improving the quality and reducing impurities in high-zinc iron ore concentrate.

[0030] Figure 2 This is a schematic diagram of improving the quality and reducing impurities in high-zinc iron concentrate. DETAILED DESCRIPTION

[0031] The following examples are intended to further illustrate the present invention in detail, but are not intended to limit the scope of protection of the claims of the present invention.

[0032] Example 1

[0033] The zinc content of a weak magnetic separation iron concentrate is 0.416%, the iron content is 65.05%, and the SiO2 content is 4.56%. The content of sphalerite and iron sphalerite in the sphalerite mineral is 0.32%, and the content of zinc iron spinel is 0.096%. The zinc content exceeds the user's quality requirement of 0.05%. The combined reagent and the combined separation process of the present invention are used to improve the quality and reduce impurities of this high-zinc iron concentrate, which specifically includes the following steps:

[0034] The iron concentrate was re-grinded with a ball mill, and the grinding concentration was 65%. After grinding, -200 mesh accounted for 95%, and -200 mesh + 400 mesh accounted for 45%. The flotation concentration was controlled at 35% for reverse flotation dezincification. The flotation process was one roughing, two fines and three sweeps. Sulfuric acid was used to adjust the pH of the ore pulp to 3. After stirring for 3 minutes, a combined activator was added to activate the sphalerite. The activator used a combination of copper sulfate and ammonium chloride in a mass ratio of 2:1. The amount of copper sulfate added in the roughing was 400g / t. After mixing and stirring for 3 minutes, a combined collector of butyl xanthate and butylamine black medicine was added in a mass ratio of 1: 1. The amount of butyl xanthate added in the roughing is 200g / t; after mixing and stirring for 3min, 45g / t of pine alcohol is added, and after mixing and stirring for 1min, aeration flotation is performed; the dosage of the first two scavenging agents is halved successively, and the concentrating is blank concentrating without adding agents; the third scavenging uses metal ion-organic complexes as activators and collectors, lead nitrate is used as metal ions, the dosage is 200g / t, benzohydroxamic acid is used as organic matter, the molar ratio is 1:1, and pine alcohol is used as a frother, the dosage is 15g / t; the roughing flotation time is 6min, and the scavenging and concentrating flotation time is 3min. The reverse flotation tailings obtained are subjected to two weak magnetic separations using a permanent magnetic drum magnetic separator, the magnetic separation intensity of the first weak magnetic separation is 400Gs, and the magnetic separation intensity of the second weak magnetic separation is 600Gs, and finally the flotation zinc concentrate and high-purity iron concentrate products are obtained. The final high-zinc iron concentrate quality improvement and impurity reduction test results are shown in Table 1.

[0035] Table 1 Test results of improving quality and reducing impurities of high zinc iron concentrate under the conditions of Example 1

[0036]

[0037] It can be seen from Table 1 that after the above process flow, the zinc in the high-zinc iron concentrate is reduced from 0.416% to 0.058% after reverse flotation, and the removal rate is 85.08%. After two magnetic separations, the high-purity iron concentrate obtained has TFe>70%, Zn<0.05%, SiO2<0.3%, the iron recovery rate is above 98%, and the loss rate does not exceed 3%.

[0038] Example 2

[0039] The zinc content of a weak magnetic separation iron concentrate is 0.356%, the iron content is 64.05%, and the SiO2 content is 5.56%. The content of sphalerite and iron sphalerite in the sphalerite mineral is 0.22%, and the content of zinc iron spinel is 0.136%. The zinc content exceeds the user's quality requirement of 0.05%. The combined reagent and the combined separation process of the present invention are used to improve the quality and reduce impurities of this high-zinc iron concentrate, which specifically includes the following steps:

[0040] The iron concentrate was re-grinded with a ball mill, and the grinding concentration was 65%. After grinding, -200 mesh accounted for 98%, and -200 mesh + 400 mesh accounted for 45%. The flotation concentration was controlled at 35% for reverse flotation dezincification. The flotation process was one roughing, two fines and three sweeps. Sulfuric acid was used to adjust the pH of the ore pulp to 3. After stirring for 3 minutes, a combined activator was added to activate sphalerite. The activator used a combination of copper sulfate and citric acid in a mass ratio of 1:1. The amount of copper sulfate added in the roughing was 800g / t. After mixing and stirring for 3 minutes, a combined collector of butyl xanthate and n-dodecyl mercaptan was added in a mass ratio of 5. :1, the amount of butyl xanthate added in the roughing is 200g / t; after mixing and stirring for 3min, 45g / t of pine oil is added, and after mixing and stirring for 1min, aeration flotation is performed; the dosage of the first two scavenging agents is halved successively, and the concentrating is blank concentrating without adding agents; the third scavenging uses metal ion-organic complex as activator and collector, lead nitrate is used as metal ion, the dosage is 200g / t, salicylic hydroxamic acid is used as organic matter, the molar ratio is 1:1, and pine oil is used as frother, the dosage is 15g / t; the roughing flotation time is 6min, and the scavenging and concentrating flotation time is 3min. The reverse flotation tailings obtained are subjected to two weak magnetic separations and impurities removal using a permanent magnetic drum magnetic separator. The magnetic separation intensity of the first weak magnetic separation is 400Gs, and the magnetic separation intensity of the second weak magnetic separation is 600Gs, and finally the flotation zinc concentrate and high-purity iron concentrate products are obtained. The final high-zinc iron concentrate quality improvement and impurity reduction test results are shown in Table 2.

[0041] Table 2 Test results of improving quality and reducing impurities of high zinc iron concentrate under the conditions of Example 2

[0042]

[0043] It can be seen from Table 2 that after the above process flow, the zinc in the high-zinc iron concentrate is reduced from 0.356% to 0.067% after reverse flotation, and the removal rate is 64.92%. After two magnetic separations, the high-purity iron concentrate obtained has TFe>71%, Zn<0.05%, SiO2<0.3%, the iron recovery rate is above 98%, and the loss rate does not exceed 3%.

[0044] Comparative Example 1

[0045] The zinc content of a weak magnetic separation iron concentrate is 0.416%, the iron content is 65.05%, and the SiO2 content is 4.56%. The content of sphalerite and iron sphalerite in the sphalerite mineral is 0.32%, and the content of zinc iron spinel is 0.096%. The zinc content exceeds the user's quality requirement of 0.05%. The separation process of the present invention is used to improve the quality and reduce the impurities of this high-zinc iron concentrate. The third sweeping process no longer uses metal ion-organic complexes as activators and collectors, and specifically includes the following steps:

[0046] The iron concentrate was re-grinded with a ball mill, and the grinding concentration was 65%. After grinding, -200 mesh accounted for 95%, and -200 mesh + 400 mesh accounted for 45%. The flotation concentration was controlled at 35% for reverse flotation dezincification. The flotation process was one roughing, two fines and three sweepings. Sulfuric acid was used to adjust the pH of the ore pulp to 3. After stirring for 3 minutes, a combined activator was added to activate the sphalerite. The activator used a combination of copper sulfate and ammonium chloride with a mass ratio of 2:1. The amount of copper sulfate added in the roughing was 400g / t. After mixing and stirring for 3 minutes, a combined collector of butyl xanthate and butylamine black medicine was added with a mass ratio of 1:1. The amount of butyl xanthate added in the roughing was 200g / t. After mixing and stirring for 3 minutes, 45g / t of pine oil was added, and aeration flotation was performed after mixing and stirring for 1 minute. The above-mentioned reagents were used in all three sweepings, and the dosage of the reagents was halved successively. The fine selection was blank selection without adding any reagents. The roughing flotation time was 6 minutes, and the sweeping and fine selection flotation time was 3 minutes. The reverse flotation tailings were subjected to two weak magnetic separations using a permanent magnetic drum magnetic separator. The magnetic separation intensity of the first weak magnetic separation was 400 Gs, and the magnetic separation intensity of the second weak magnetic separation was 600 Gs. Finally, flotation zinc concentrate and high-purity iron concentrate products were obtained. The final high-zinc iron concentrate quality improvement and impurity reduction test results are shown in Table 3.

[0047] Table 3 Comparative results of high zinc iron concentrate quality improvement and impurity reduction test under the conditions of Example 1

[0048]

[0049] It can be seen from Table 3 that after the above process flow, when the metal ion-organic complex is no longer used as an activator and collector in the third scavenging, the zinc in the high-zinc iron concentrate is reduced from 0.416% to 0.105% after reverse flotation, which is greater than 0.1%, and the removal rate is 56.46%. The zinc removal depth has not reached the ideal state; after two magnetic separations, the high-purity iron concentrate obtained has TFe<70%, Zn>0.05%, SiO2>0.3%, and the iron loss rate exceeds 3%.

[0050] Comparative Example 2

[0051] The zinc content of a weak magnetic separation iron concentrate is 0.416%, the iron content is 61.05%, and the SiO2 content is 4.56%. The content of sphalerite and iron sphalerite in the sphalerite mineral is 0.32%, and the content of zinc iron spinel is 0.096%. The zinc content exceeds the user's quality requirement of 0.05%. The separation process of the present invention is used to improve the quality and reduce impurities of this high-zinc iron concentrate. The flotation reagent uses a single activator reagent, which specifically includes the following steps:

[0052] The iron concentrate was re-grinded with a ball mill, and the grinding concentration was 65%. After grinding, -200 mesh accounted for 95%, and -200 mesh + 400 mesh accounted for 45%. The flotation concentration was controlled at 35% for reverse flotation dezincification. The flotation process was one roughing, two fines and three sweeps. Sulfuric acid was used to adjust the pH of the ore pulp to 3. After stirring for 3 minutes, activator copper sulfate was added to activate sphalerite. The amount of copper sulfate added in the roughing was 400g / t. After mixing and stirring for 3 minutes, the combined collectors butyl xanthate and butylamine black medicine were added. The mass ratio is 1:1, and the amount of butyl xanthate added in the roughing is 200g / t; after mixing and stirring for 3 minutes, 45g / t of pine oil is added, and after mixing and stirring for 1 minute, aeration flotation is performed; the dosage of the first two scavenging agents is halved successively, and the fine selection is blank fine selection without adding drugs; the third scavenging uses benzohydroxamic acid as a collector, the dosage is 200g / t, and the frother uses pine oil, the dosage is 15g / t; the roughing flotation time is 6min, and the scavenging and fine flotation time is 3min. The reverse flotation tailings obtained are subjected to two weak magnetic separations using a permanent magnetic drum magnetic separator. The magnetic separation intensity of the first weak magnetic separation is 400Gs, and the magnetic separation intensity of the second weak magnetic separation is 600Gs, and finally the flotation zinc concentrate and high-purity iron concentrate products are obtained. The final high-zinc iron concentrate quality improvement and impurity reduction test results are shown in Table 4.

[0053] Table 4 Comparative results of the test on improving quality and reducing impurities of high zinc iron concentrate under the conditions of Example 2

[0054]

[0055] It can be seen from Table 4 that after the above process flow, when only a single activator is used, the zinc in the high-zinc iron concentrate is reduced from 0.416% to 0.118% after reverse flotation, which is greater than 0.1%, and the removal rate is only 69.28%. The zinc removal depth has not reached the ideal state; after two magnetic separations, the high-purity iron concentrate obtained has TFe<67%, Zn>0.05%, SiO2>0.5%, and the iron loss rate exceeds 3%.

[0056] Comparative Example 3

[0057] The zinc content of a weak magnetic separation iron concentrate is 0.416%, the iron content is 61.05%, and the SiO2 content is 4.56%. The content of sphalerite and iron sphalerite in the sphalerite mineral is 0.32%, and the content of zinc iron spinel is 0.096%. The zinc content exceeds the user's quality requirement of 0.05%. The separation process of the present invention is used to improve the quality and reduce impurities of this high-zinc iron concentrate, and the flotation reagent is a single collector, which specifically includes the following steps:

[0058] The iron concentrate was re-grinded with a ball mill, and the grinding concentration was 65%. After grinding, -200 mesh accounted for 95%, and -200 mesh + 400 mesh accounted for 45%. The flotation concentration was controlled at 35% for reverse flotation dezincification. The flotation process was one roughing, two fines and three sweeps. Sulfuric acid was used to adjust the pH of the pulp to 3. After stirring for 3 minutes, copper sulfate, an activator, was added to activate sphalerite. The activator used a combination of copper sulfate and ammonium chloride with a mass ratio of 2:1. The amount of copper sulfate added in the roughing was 400g / t. Mixing and stirring for 3 minutes After 3 minutes, the collector butyl xanthate was added, and the amount of butyl xanthate added in the roughing selection was 200g / t; after mixing and stirring for 3 minutes, 45g / t of pine oil was added, and after mixing and stirring for 1 minute, aeration flotation was performed; the dosage of the first two scavenging agents was halved successively, and the selection was blank selection without adding agents; the third scavenging selection used benzohydroxamic acid as a collector, the dosage was 200g / t, and the frother used pine oil, the dosage was 15g / t; the roughing flotation time was 6min, and the scavenging and selection flotation time was 3min. The reverse flotation tailings obtained were subjected to two weak magnetic separations using a permanent magnetic drum magnetic separator. The magnetic separation intensity of the first weak magnetic separation was 400Gs, and the magnetic separation intensity of the second weak magnetic separation was 600Gs, and finally the flotation zinc concentrate and high-purity iron concentrate products were obtained. The final high-zinc iron concentrate quality improvement and impurity reduction test results are shown in Table 4.

[0059] Table 5 Comparative results of the test on improving quality and reducing impurities of high zinc iron concentrate under the conditions of Example 3

[0060]

[0061] It can be seen from Table 5 that after the above process flow, when only a single collector is used, the zinc in the high-zinc iron concentrate is reduced from 0.416% to 0.136% after reverse flotation, which is greater than 0.1%, and the removal rate is only 61.89%. The zinc removal depth has not reached the ideal state; after two magnetic separations, the high-purity iron concentrate obtained has TFe<67%, Zn>0.1%, SiO2>0.4%, and the iron loss rate exceeds 3%.

Claims

1. A method for preparing high-purity iron concentrate by improving the quality of high-zinc iron concentrate and reducing silicon content, characterized in that: The high-zinc iron concentrate is subjected to pulping and regrinding treatment to obtain regrinding pulp; the regrinding pulp is subjected to reverse flotation, the flotation concentrate is zinc concentrate, the flotation tailings is iron concentrate, and the flotation tailings are subjected to magnetic separation to obtain high-purity iron concentrate and high-silicon tailings; the high-zinc iron concentrate contains sphalerite, sphalerite, ferrospinite and magnetite; During the reverse flotation process, the pulp concentration is adjusted to 30-40wt%, the pulp pH is adjusted to 3-5, and the reverse flotation process is: one roughing selection + two cleaning selections + three scavenging selections; In the roughing process, at least one of ammonium chloride, ammonium carbonate, citric acid and sodium citrate is mixed with copper sulfate in a mass ratio of (0.5-3):1 as a combined activator, at least one of butylamine black medicine, n-dodecyl mercaptan and tert-dodecyl mercaptan is mixed with xanthate in a mass ratio of 1:(1-10) as a combined collector, and at least one of pineol, methyl isobutyl carbinol, diethyl phthalate and diethylene glycol butyl ether is used as a foaming agent; In the scanning process, at least one of ammonium chloride, ammonium carbonate, citric acid and sodium citrate is used as a combined activator in a mass ratio of (0.5-3):1 with copper sulfate in the first two scannings, at least one of butylamine black medicine, n-dodecyl mercaptan and tert-dodecyl mercaptan is used as a combined collector in a mass ratio of 1:(1-10), and at least one of pineneol, methyl isobutyl carbinol, diethyl phthalate and diethylene glycol butyl ether is used as a foaming agent; in the third scanning, a metal ion-hydroxamic acid complex is used as a collector; the metal ion in the metal ion-hydroxamic acid complex includes Pb 2+ , Ca 2+ Mg 2+ , Cu 2+ 、Al 2+ , Mn 2+ At least one of the hydroxamic acid ligands, the hydroxamic acid ligand includes at least one of benzohydroxamic acid, octylhydroxamic acid, and salicylic hydroxamic acid, and the molar ratio of the metal ion to the hydroxamic acid ligand is 1:(1-5); The particle size of the high-zinc iron concentrate satisfies that the mass percentage content of the -200 mesh particle size is greater than 70%, and the iron grade is 58%~66%, and the mass percentage content of zinc is greater than 0.3%.

2. The method for preparing high-purity iron concentrate by improving the quality of high-zinc iron concentrate and reducing silicon content according to claim 1, characterized in that: The regrinding process grinds the high-zinc iron ore to a particle size that satisfies the mass percentage content of the -200 mesh particle size of more than 90%, and the mass percentage content of the -200 mesh to +400 mesh particle size is 40-45%.

3. The method for preparing high-purity iron concentrate by improving the quality of high-zinc iron concentrate and reducing silicon content according to claim 1, characterized in that: The concentration of the combined activator added to the ore pulp during the roughing process is 400-1000 g / t, and the mass of the combined activator is measured by the mass of copper sulfate; the concentration of the combined collector added to the ore pulp is 100-300 g / t, and the mass of the combined collector is measured by the mass of xanthate; the concentration of the frother added to the ore pulp is 15-50 g / t; The xanthate is at least one of butyl xanthate, isobutyl xanthate, amyl xanthate and isobutyl xanthate.

4. The method for preparing high-purity iron concentrate by improving the quality of high-zinc iron concentrate and reducing silicon content according to claim 1, characterized in that: The concentration of the combined activator added to the ore pulp during the first two scavenging processes is 200-500 g / t, and the mass of the combined activator is measured by the mass of copper sulfate; the concentration of the combined collector added to the ore pulp is 50-150 g / t, and the mass of the combined collector is measured by the mass of xanthate; the concentration of the frother added to the ore pulp is 7-25 g / t; The xanthate is at least one of butyl xanthate, isobutyl xanthate, amyl xanthate and isobutyl xanthate; During the third scavenging process, the concentration of the metal ion-hydroxamic acid complex added to the ore pulp is 100-300 g / t.

5. The method for preparing high-purity iron concentrate by improving the quality of high-zinc iron concentrate and reducing silicon according to claim 1, characterized in that: The magnetic separation includes two stages of weak magnetic separation processes.

6. The method for preparing high-purity iron concentrate by improving the quality of high-zinc iron concentrate and reducing silicon content according to claim 5, characterized in that: The two-stage weak magnetic concentration processes both use permanent magnetic drum magnetic separators, and the magnetic field strength is 300~800Gs.

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