Magnetite preparation method, multi-metal separation method and iron precipitation method of zinc leachate

Abstract

The invention provides a magnetite preparation method, a multi-metal separation method and an iron precipitation method of zinc leachate. The multi-metal separation method comprises the following steps: S1, providing trivalent iron minerals; s2, the trivalent iron minerals are subjected to acid pickling treatment, and multi-metal iron minerals are obtained; the acid pickling treatment comprises the steps that the trivalent iron minerals are placed in an acid solution to be mixed for the first time, solid-liquid separation is conducted after the first mixing, and acid pickling liquid and the multi-metal iron minerals are obtained; s3, alkali liquor and a ferrous solution are mixed into the multi-metal iron mineral, and premixed liquor is obtained; carrying out second mixing on the premixed solution to obtain a reaction solution; s4, the reaction liquid is subjected to magnetic separation, and magnetite concentrate and turbid liquid are obtained; and the turbid liquid is subjected to solid-liquid separation, and alkaline separation liquid and polymetallic tailings are obtained. The magnetite concentrate with the iron content as high as 61% and lower entrained impurity metal content can be obtained, and the impurity metal of the trivalent iron minerals is separated into the multi-metal tailings.

Description

Technical Field

[0001] The invention relates to the technical field of separation and recovery of metal ions in a hydrometallurgical zinc leaching solution, and in particular to a magnetite preparation method, a multi-metal separation method and an iron precipitation method for a zinc leaching solution. Background Art

[0002] The hydrometallurgical zinc smelting process produces 85% of zinc, including the roasting-leaching-electrolysis process. The electrolysis link is the key step to extract zinc from the solution to form metallic zinc. In this process, in order to ensure the smooth progress of the electrolysis process and the quality of the final zinc product, strict requirements are placed on the impurity element content of the electrolyte. The notable feature of the zinc leachate is that it contains a variety of elements with high concentrations; in addition to high concentrations of zinc and iron, it can also contain a variety of heavy metal impurity elements such as lead, copper, cobalt, and aluminum. Iron, as the most important impurity element, will affect the subsequent electrolytic refining of zinc. Therefore, it is necessary to treat the leachate with iron precipitation, convert the iron into precipitate, and separate the solid and liquid to obtain iron-removing waste slag.

[0003] Iron removal slag mainly includes iron alum slag obtained by the yellow sodium iron alum method, goethite slag obtained by the goethite method, and hematite slag obtained by the hematite method. Iron alum slag and goethite slag have a low iron content, a large slag volume, and a high content of impurity metals, so they are included in the "National Hazardous Waste List" (hazardous waste codes are 321-0005-48 and 321-007-48 respectively); there is currently no economical and efficient method for treating and recycling iron alum slag and goethite slag. Although the hematite method can theoretically reach 70% iron content, the hematite process requires high temperature and high pressure conditions, and has relatively high requirements for equipment. Only a few companies have mastered this technology. Therefore, it is of great significance to study and develop a simple and easy zinc leaching solution treatment process to obtain iron slag with less slag volume, higher iron content, lower impurity metal content and direct utilization.

[0004] In view of this, it is necessary to provide a method for preparing magnetite, a method for separating multiple metals and a method for precipitating iron from a zinc leaching solution, so as to solve or at least alleviate the technical problem of how to obtain iron slag with a higher iron content and a lower content of entrained impurity metals. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for preparing magnetite, a method for separating multiple metals and a method for precipitating iron from zinc leaching solution, aiming to solve the above-mentioned technical problem of how to obtain iron slag with higher iron content and lower content of entrained impurity metals.

[0006] To achieve the above object, the present invention provides a multi-metal separation method based on magnetite, comprising the steps of:

[0007] S1, providing a ferric iron mineral; the ferric iron mineral contains iron and other impurity metals;

[0008] S2, performing an acid wash treatment on the ferric iron mineral to obtain a polymetallic iron mineral; the acid wash treatment comprises: placing the ferric iron mineral in an acid solution for a first mixing, and performing solid-liquid separation after the first mixing to obtain an acid wash solution and the polymetallic iron mineral; the pH of the acid solution is 1 to 3.5;

[0009] S3, mixing an alkali solution and a ferrous solution into the polymetallic iron mineral to obtain a premixed solution; performing a second mixing on the premixed solution to obtain a reaction solution; the alkali solution contains an alkaline substance, and the concentration of the alkaline substance in the premixed solution is 0.5-1.2 mol / L; the molar ratio of the iron element in the ferrous solution to the iron element in the polymetallic iron mineral is 1:1.5-5;

[0010] S4, performing magnetic separation on the reaction liquid to obtain magnetite concentrate and suspension; performing solid-liquid separation on the suspension to obtain alkaline separation liquid and polymetallic tailings.

[0011] Furthermore, the trivalent iron mineral includes one or more of pyrite, goethite, ferrihydrite, and schrenkiolite; and the other impurity metals include one or more of aluminum, manganese, calcium, zinc, and lead.

[0012] Furthermore, the first mixing is performed for 1 to 20 hours at a temperature of 15 to 60° C.; the second mixing is performed for 0.5 to 10 hours at a temperature of 30 to 100° C.

[0013] Furthermore, the acid solution includes one or more of sulfuric acid solution, hydrochloric acid solution, acetic acid solution, and nitric acid solution.

[0014] Furthermore, the alkaline substance includes one or more of sodium hydroxide and potassium hydroxide; the ferrous solution includes one or more of ferrous sulfate solution and ferrous chloride solution.

[0015] Furthermore, the alkaline solution includes the alkaline separation solution.

[0016] Furthermore, the polymetallic iron mineral accounts for 1 to 20 g / L in the premixed solution.

[0017] The present invention also provides a method for preparing magnetite based on trivalent iron minerals, comprising the steps of:

[0018] S01, providing a trivalent iron mineral; the trivalent iron mineral contains iron and other impurity metals;

[0019] S02, performing an acid wash treatment on the ferric iron mineral to obtain a polymetallic iron mineral; the acid wash treatment comprises: placing the ferric iron mineral in an acid solution for a first mixing, and performing solid-liquid separation after the first mixing to obtain an acid wash solution and the polymetallic iron mineral; the pH of the acid solution is 1 to 3.5;

[0020] S03, mixing an alkali solution and a ferrous solution into the polymetallic iron mineral to obtain a premixed solution; performing a second mixing on the premixed solution to obtain a reaction solution; the alkali solution contains an alkaline substance, and the concentration of the alkaline substance in the premixed solution is 0.5-1.2 mol / L; the molar ratio of the iron element in the ferrous solution to the iron element in the polymetallic iron mineral is 1:2-4;

[0021] S04, separating the reaction liquid into solid and liquid to obtain an alkaline separation liquid and a solid separation containing magnetite.

[0022] The present invention also provides a method for precipitating iron in a zinc leaching solution, comprising: subjecting the zinc leaching solution to precipitating iron to obtain a trivalent iron mineral; and then treating the trivalent iron mineral with any of the above-mentioned multi-metal separation methods to obtain a magnetite concentrate and a multi-metal tailings.

[0023] Furthermore, the method further comprises: before the iron precipitation treatment, mixing the pickling solution into the zinc leaching solution.

[0024] Compared with the prior art, the present invention has at least the following advantages:

[0025] The present invention can convert ferric iron minerals containing impurity metals into raw magnetite ore, and can also obtain a magnetite concentrate with a higher iron content and a lower content of impurity metals based on a specific iron slag (such as iron alum slag), and enrich the impurity metals of the ferric iron minerals in the polymetallic tailings; the present invention first precipitates the iron ions in the hydrometallurgical zinc leaching solution in the form of ferric iron minerals and pickles to obtain polymetallic iron minerals; the polymetallic iron minerals are mixed with an alkaline solution, and then a ferrous solution is added to convert the iron-containing minerals to obtain a magnetite ore to be processed (magnetite before magnetic separation), and a magnetite concentrate and polymetallic tailings are obtained after magnetic separation and solid-liquid separation. The present invention can achieve the goals of polymetallic separation and iron element extraction, and is simple to operate, low in cost, short in cycle, and has good industrial application prospects.

[0026] Compared with traditional source iron precipitation products, magnetite is the iron oxide with the highest iron content and is an ideal raw material for ironmaking. Due to the increase in iron content, the amount of iron precipitation slag can be reduced, thereby reducing the pressure of storage and transportation; in addition, magnetite has strong magnetism and can be quickly separated from the liquid phase and other solid phases through magnetic separation, which is conducive to the separation and enrichment of iron phases and other impurity metals, and improves the current problem of generally poor iron slag sedimentation performance. Therefore, the magnetite method has greater advantages than other iron precipitation methods and is a new type of iron precipitation method with great potential, which can achieve the reduction and resource utilization of iron slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0028] Figure 1 It is the X-ray diffraction pattern of the iron alum slag before and after pickling in Comparative Example 1 of the present invention; Before washing refers to the iron alum slag (iron alum slag before pickling), and After washing refers to the polymetallic iron mineral (iron alum slag after pickling);

[0029] Figure 2 This is a morphology diagram of the iron alum slag in Comparative Example 1 of the present invention;

[0030] Figure 3 Element distribution diagram of iron alum slag in Comparative Example 1 of the present invention;

[0031] Figure 4 It is the X-ray diffraction pattern of the goethite slag in Comparative Example 2 of the present invention; Before washing refers to the goethite slag (goethite slag before pickling), and After washing refers to the polymetallic iron mineral (goethite slag after pickling);

[0032] Figure 5 This is a morphology diagram of goethite slag in Comparative Example 2 of the present invention;

[0033] Figure 6 Element distribution diagram of goethite slag in Comparative Example 2 of the present invention;

[0034] Figure 7 It is an X-ray diffraction diagram of the solid separator in Comparative Example 3 of the present invention; Goethite means that the solid separator is derived from goethite slag, and Transformed from raw waste means that the solid separator is obtained by transforming goethite slag without acid washing.

[0035] Figure 8 is the X-ray diffraction pattern of the solid separated product (magnetite before magnetic separation) in Example 1 of the present invention; Jarosite refers to the magnetite before magnetic separation derived from ferrocyanide slag, and Transformed from washed waste refers to the magnetite before magnetic separation transformed from ferrocyanide slag after acid washing;

[0036] Fig. 9 The scanning electron microscope image of the magnetite concentrate and the polymetallic tailings in Example 1 of the present invention: Concentrate refers to the magnetite concentrate, and Tailing refers to the polymetallic tailings;

[0037] Fig.10 It is an X-ray diffraction diagram of the solid separated product (magnetite before magnetic separation) in Example 2 of the present invention; Goethite refers to the magnetite before magnetic separation derived from goethite slag, and Transformed from washed waste refers to the magnetite before magnetic separation obtained by transformation of goethite slag after acid washing;

[0038] Fig.11 This is a scanning electron microscope image of the magnetite concentrate and the polymetallic tailings in Example 2 of the present invention: Concentrate refers to the magnetite concentrate, and Tailing refers to the polymetallic tailings.

[0039] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0042] When the embodiments give numerical ranges, it should be understood that, unless otherwise specified in the present invention, the two endpoints of each numerical range and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention and the technical personnel in the field of the prior art and the records of the present invention can also be used to implement the present invention using any method, equipment and material of the prior art similar or equivalent to the method, equipment and material in the embodiments of the present invention. The reagents and instruments used in the embodiments of the present invention and the comparative examples are all commercially available products. It should be noted that in the present invention, different element content detection methods will have certain fluctuations and experimental errors, which do not affect the understanding of the invention technology effect.

[0043] It should be noted that magnetite has a high iron content, and magnetite can be quickly separated from liquid phase and other solid phases by magnetic separation; in addition, the formation conditions of magnetite are simple, no high temperature and high pressure are required, and the reaction time is short, thereby improving production efficiency. Compared with other iron precipitation methods, it has great advantages and is a more ideal iron slag product. The present invention mainly converts trivalent iron minerals into magnetite concentrates, and while obtaining magnetite, other impurity metals in the trivalent iron minerals are separated.

[0044] The present invention provides a multi-metal separation method based on magnetite, comprising the steps of:

[0045] S1, providing a ferric iron mineral; the ferric iron mineral contains iron and impurity elements, the impurity elements include other impurity metals (metal elements not containing iron), and the iron element in the ferric iron mineral exists in the form of ferric iron.

[0046] Specifically, the ferric iron mineral may be derived from the iron precipitate slag produced by the zinc leaching solution; the ferric iron mineral includes one or more of pyrite, goethite, ferrihydrite, and Schmidtite, that is, the ferric iron mineral includes one or more of pyrite slag, goethite slag, ferrihydrite slag, and Schmidtite slag; pyrite may be yellow potassium / sodium / ammonia ferroaluminate; the other impurity metals may include one or more of aluminum, manganese, calcium, zinc, and lead. Exemplarily, the ferric iron mineral includes or is pyrite slag, and the pyrite slag contains yellow sodium ferroaluminate, goethite, zinc sulfate, and zinc ferrite; and / or, the ferric iron mineral includes or is goethite slag, and the goethite slag contains goethite, yellow sodium ferroaluminate, zinc sulfate, and calcium sulfate.

[0047] As an element description of the ferric iron mineral, through quantitative analysis of elements by X-ray fluorescence spectroscopy, the iron content in the ferric iron mineral is generally 20-50%, the aluminum content is generally 0.1-10%, the manganese content is generally 0.1-3%, the calcium content is generally 0.1-10%, the zinc content is generally 15-60%, the sulfur content is generally 3-16%, and the lead content is generally 0.05-10%.

[0048] When the trivalent iron mineral is the pyrite alum slag, through quantitative analysis of elements by X-ray fluorescence spectroscopy, the iron content in the trivalent iron mineral is generally 30-50%, the aluminum content is generally 0.5-2%, the manganese content is generally 0.1-1%, the calcium content is generally 0.3-1%, the zinc content is generally 15-30%, the sulfur content is generally 7-11%, and the lead content is generally 1-2%, calculated by mass percentage.

[0049] When the trivalent iron mineral is the goethite slag, through quantitative analysis of elements by X-ray fluorescence spectroscopy, the iron content in the trivalent iron mineral is generally 20-40%, the aluminum content is generally 0.5-1.5%, the manganese content is generally 0.5-1.5%, the calcium content is generally 3-8%, the zinc content is generally 20-40%, the sulfur content is generally 10-16%, and the lead content is generally 0.05-0.3%, calculated by mass percentage.

[0050] S2, performing pickling treatment on the ferric iron mineral to obtain a polymetallic iron mineral; the pickling treatment comprises: placing the ferric iron mineral in an acid solution for a first mixing, and performing solid-liquid separation after the first mixing to obtain a pickling solution and the polymetallic iron mineral, wherein the polymetallic iron mineral is an iron mineral containing multiple metals.

[0051] In the present invention, the pH of the acid solution is 1 to 3.5; the mass volume ratio of the trivalent iron mineral to the acid solution can be 1:10 to 50 g / mL. The concentration of the acidic substance in the acid solution can be 0.1 to 0.2 mol / L. The acid solution includes one or more of a sulfuric acid solution, a hydrochloric acid solution, an acetic acid solution, and a nitric acid solution; the acidic substance can include one or more of sulfuric acid, hydrochloric acid, acetic acid, and nitric acid.

[0052] In the present invention, the first mixing time may be 1 to 20 hours, and the first mixing may be performed at a temperature of 15 to 60°C; further, the first mixing time may be 10-20 hours, and the first mixing may be performed at a temperature of 25 to 60°C.

[0053] S3, mixing an alkali solution and a ferrous solution into the polymetallic iron mineral to obtain a premixed solution; and performing a second mixing on the premixed solution to obtain a reaction solution.

[0054] In the present invention, the premixed liquid is an initial mixed liquid of the polymetallic iron mineral, the alkali solution and the ferrous solution; the alkali solution and the ferrous solution can be sequentially mixed into the polymetallic iron mineral.

[0055] In the present invention, the alkali solution contains alkaline substances, and the concentration of the alkaline substances in the premixed solution is 0.5-1.2 mol / L or 0.7-0.9 mol / L; the concentration of the alkaline substances in the alkali solution can be 0.8-1.2 mol / L or 0.8-2 mol / L, and the volume ratio of the alkali solution to the ferrous solution can be 1-20:1 or 2-10:1; the proportion of the polymetallic iron mineral in the premixed solution is 1-20 g / L or 5-15 g / L.

[0056] In the present invention, the alkaline substance includes one or more of sodium hydroxide and potassium hydroxide. In order to reduce the amount of wastewater discharged and the consumption of alkali, the alkali solution may also include the alkaline separation liquid.

[0057] In the present invention, the molar ratio of the iron element in the ferrous solution to the iron element in the polymetallic iron mineral is 1:1.5-5 or 1:1.8-3; that is, the iron element in the ferrous solution is ferrous, the iron element in the ferric iron mineral and the polymetallic mineral is ferric iron, and the molar ratio of the ferrous iron (derived from the ferrous solution) to the ferric iron (derived from the polymetallic tailings) is 1:1.5-5 or 1:1.8-3; the ferrous solution includes one or more of a ferrous sulfate solution and a ferrous chloride solution; the concentration of ferrous ions in the ferrous solution can be 0.05-0.5 mol / L or 0.2-0.4 mol / L.

[0058] In the present invention, the second mixing time may be 0.5 to 10 hours, and the second mixing may be performed at a temperature of 30 to 100° C.; further, the second mixing time may be 3 to 5 hours, and the second mixing may be performed at a temperature of 40 to 80° C.

[0059] S4, subjecting the reaction liquid to magnetic separation to obtain magnetite concentrate and suspension; subjecting the suspension to solid-liquid separation to obtain alkaline separation liquid and polymetallic tailings; the output of the polymetallic tailings is less than that of the magnetite concentrate.

[0060] In order to convert the ferric iron mineral containing impurity metals into magnetite, the present invention also provides a method for preparing magnetite based on the ferric iron mineral, comprising the steps of:

[0061] S01, providing a ferric iron mineral; the ferric iron mineral contains iron and other impurity metals.

[0062] S02, subjecting the ferric iron mineral to an acid wash treatment to obtain a polymetallic iron mineral; the acid wash treatment comprises: placing the ferric iron mineral in an acid solution for a first mixing, and performing solid-liquid separation after the first mixing to obtain an acid wash solution and the polymetallic iron mineral; the pH of the acid solution is 1 to 3.5.

[0063] S03, mixing alkali solution and ferrous solution into the polymetallic iron mineral to obtain a premixed solution; performing a second mixing on the premixed solution to obtain a reaction solution; the alkali solution contains an alkaline substance, and the concentration of the alkaline substance in the premixed solution is 0.5-1.2 mol / L; the molar ratio of the iron element in the ferrous solution to the iron element in the polymetallic iron mineral is 1:2-4.

[0064] S04, separating the reaction liquid into solid and liquid to obtain an alkaline separation liquid and a solid separation containing magnetite.

[0065] In the magnetite preparation method, the technical solutions in step S01, step S02 and step S03 are the same as those in step S1, step S2 and step S3 in the multi-metal separation method, and the limitations of relevant parameters and reactants are also the same; in the magnetite preparation method, the solid separator containing magnetite can be magnetically separated to obtain magnetite concentrate.

[0066] In order to realize the resource treatment of zinc leachate, the present invention also provides a method for iron precipitation of zinc leachate, comprising: subjecting the zinc leachate to iron precipitation treatment, obtaining a zinc-containing supernatant and trivalent iron minerals after solid-liquid separation; and then treating the trivalent iron minerals by any of the multi-metal separation methods described above to obtain magnetite and multi-metal tailings. The concentration of iron in the zinc leachate is 10-50 g / L, the concentration of zinc is 90-110 g / L, and the zinc leachate also contains other metal elements such as magnesium, aluminum, manganese, and calcium; the iron in the zinc leachate exists in the form of divalent iron ions.

[0067] In the present invention, the iron precipitation method may further include: before the iron precipitation treatment, mixing the pickling solution into the zinc leaching solution to reduce the amount of wastewater discharge and achieve the enrichment and reuse of valuable metals.

[0068] In the present invention, the method for precipitating iron in the zinc leaching solution may include: 2+ All oxidized to Fe 3+ (H2O2 oxidation is used, H2O2 and Fe in the zinc leaching solution 2+ The molar ratio can be 0.8-1.5:1) to obtain a pretreatment liquid; then adjust the pH value of the pretreatment liquid to 1.5±0.2; thereafter, stir the reaction at 90-97°C for 5-7h, and separate the solid-liquid to obtain the trivalent iron mineral, which includes ferrocyanide slag.

[0069] Alternatively, the pH value of the zinc leaching solution is adjusted to 4.0±0.2; then, air is continuously introduced into the zinc leaching solution, and the reaction is stirred at 75-85° C. for 5-7 hours, and the pH is ensured to be 4.0±0.2 during the reaction. After the reaction is completed, the trivalent iron mineral is obtained by solid-liquid separation, and the trivalent iron mineral includes goethite slag.

[0070] It should be pointed out that the types of elements in the wet zinc smelting leachate are complex, and the concentrations of Zn and Fe are extremely high. Impurity elements such as Zn, Al, and Ca are easily doped into the iron slag during the iron precipitation process. In the present invention, the iron ions in the wet zinc smelting leachate are first precipitated in the form of trivalent iron minerals, and acid-washed to obtain iron minerals containing multiple metals. The iron mineral containing multiple metals is mixed with an alkaline solution, and then a ferrous solution is added to convert the iron-containing minerals to obtain the magnetite ore to be processed, and the magnetite concentrate and the polymetallic tailings are obtained by magnetic separation to separate the impurities in the magnetite ore. Conventional iron precipitation products are mostly metastable iron-containing minerals. The present invention can transform them into thermodynamically more stable magnetite with magnetic separation performance, and realize direct separation from polymetallic impurities under the action of an external magnetic field.

[0071] The following are specific examples of the present invention:

[0072] Comparative Example 1

[0073] 1. Take a zinc leaching solution, which is a zinc leaching solution obtained by hot acid leaching (wet zinc smelting leaching solution). The element analysis results of the zinc leaching solution are shown in Table 1. The iron in the zinc leaching solution exists in the form of divalent iron. The element analysis method in Table 1 is ICP-OES, and the element content is the concentration of the corresponding element in the zinc leaching solution.

[0074] Table 1: Element distribution of hydrometallurgical zinc leaching solution (in mg / L)

[0075]

[0076] 2. The zinc leaching solution is subjected to iron precipitation treatment to obtain iron alum residue (yellow iron alum residue); the iron precipitation treatment process is: using H2O2 to remove Fe 2+ All oxidized to Fe 3+ , where the amount of H2O2 is related to the amount of Fe 2+ The molar ratio of the substances is 1:1; the pH value is adjusted to 1.5 with 1 mol / L NaOH solution, and after stirring the reaction at 95°C for 6 hours, solid-liquid separation is performed to obtain iron alum slag.

[0077] 3. Take 1 g of the iron alum residue obtained by precipitating iron in the zinc leaching solution, mix it with 40 mL of 0.11 mol / L (pH = 3) acetic acid solution, shake it at room temperature for 16 hours (pickling), and then perform solid-liquid separation to obtain a pickling solution and polymetallic iron minerals; the iron content in the pickling solution is less than 5 ppm.

[0078] Depend on Figure 1 It can be seen that the zinc leaching solution precipitates iron to obtain ferroalloy slag, the main phase of which includes yellow sodium ferroalloy, and its main phase also includes goethite, zinc sulfate and zinc ferrite; during the pickling process, zinc sulfate is dissolved and removed.

[0079] Depend on Figure 2-3 It can be seen from Table 2 that the morphology of iron alum slag is complex and the particle size is uneven; the iron alum slag is composed of a mixture of iron alum, zinc sulfate, lead sulfate and other particles, which are interwoven. The element analysis method in Table 2 is selected point energy spectrum element quantitative analysis (SEM-EDS), and the element content is the mass proportion of the corresponding element in the selected element.

[0080] Table 2: Quantitative analysis of selected energy spectrum elements of iron alum slag (corresponding to Figure 2 )

[0081]

[0082] It can be seen from Table 3 that the content of impurity element zinc in the iron alum slag before and after pickling is reduced from 18.9% to 9.21%. The element analysis method in Table 3 is X-ray fluorescence spectroscopy element quantitative analysis, and the element content is the mass proportion of the corresponding element in the solid sample.

[0083] Table 3: X-ray fluorescence spectroscopy element quantitative analysis of iron alum slag before and after pickling (%)

[0084]

[0085] Therefore, although the pickling method in this embodiment can wash away some zinc impurities in iron alum, the removal effect on other impurity elements is not obvious. The iron alum slag (polymetallic iron mineral) after pickling still contains a variety of impurity metals and requires further treatment.

[0086] Comparative Example 2

[0087] 1. The zinc leachate (same as comparative example 1) is subjected to iron precipitation treatment to obtain goethite slag; the process of iron precipitation treatment is as follows: taking the zinc leachate, adjusting the pH value to 4.0 with 1 mol / L NaOH solution, continuously introducing air into the zinc leachate, stirring and reacting at 80° C. for 6 h, replenishing NaOH solution in time during the reaction to ensure that the pH is about 4.0, and obtaining goethite slag by solid-liquid separation after the reaction.

[0088] 2. Take 1 g of the goethite slag obtained by precipitation of iron in zinc leaching solution, mix it with 40 mL of 0.11 mol / L (pH=3) acetic acid solution, shake it at room temperature for 16 h (pickling), and then perform solid-liquid separation to obtain a pickling solution and polymetallic iron minerals; the iron content in the pickling solution is less than 5 ppm.

[0089] Depend on Figure 4 It can be seen that the crystal form of the goethite slag obtained by iron precipitation in zinc leaching solution is poor; the main components of the goethite slag are goethite, natantia ferrocyanide, zinc sulfate and calcium sulfate; soluble and slightly soluble impurities such as zinc sulfate and calcium sulfate are dissolved and removed during the pickling process.

[0090] Depend on Figure 5-6 As shown in Table 4, goethite slag is mainly composed of long and large calcium sulfate particles and small goethite agglomerates. The element analysis method in Table 4 is selected point energy spectrum element quantitative analysis (SEM-EDS), and the element content is the mass proportion of the corresponding element in the selected element.

[0091] Table 4: Quantitative analysis of selected-point energy spectrum elements of goethite slag (corresponding to Figure 5 )

[0092]

[0093] As can be seen from Table 5, after pickling of goethite, the iron content increased from 31.6% to 59.9%, and the contents of impurity elements zinc, sulfur and calcium decreased from 23.2%, 14.1% and 5.40% to 10.4%, 4.38% and 0.15% respectively. However, the contents of impurity elements such as lead and aluminum did not change before and after pickling, and even showed signs of increasing. The element analysis method in Table 5 is X-ray fluorescence tube element quantitative analysis, and the element content is the mass proportion of the corresponding element in the solid sample.

[0094] Table 5: X-ray fluorescence spectrometry element quantitative analysis of goethite slag before and after pickling (%)

[0095]

[0096] Although the above pickling method can reduce the content of impurity elements Zn, S and Ca, impurity elements such as Al and Pb are still mixed in the goethite slag (polymetallic iron mineral) after pickling and are difficult to remove, resulting in the goethite slag being difficult to handle and being environmentally harmful.

[0097] Comparative Example 3

[0098] Take 0.746g of goethite slag (same as comparative example 2) and mix it with 50mL of 1mol / L NaOH solution, and then add 13.3mL of 0.3mol / L ferrous sulfate solution to obtain a premixed solution; stir the premixed solution at 60°C for 4h to obtain a reaction solution.

[0099] After the reaction is completed, the suspended reaction solution is centrifuged, and the solid fraction is collected and freeze-dried. The obtained solid fraction is analyzed by XRD. The results are as follows: Figure 4 shown.

[0100] See also Figure 7 As shown, the magnetite characteristic peak of the solid separator in this comparative example is weak, and an obvious goethite peak is still retained. This is mainly because impurities such as calcium sulfate affect the crystallization of magnetite crystals, thereby inhibiting the conversion of goethite to magnetite.

[0101] Example 1

[0102] 0.456 g of polymetallic iron mineral (iron alum residue after pickling, same as in comparative example 1) was mixed with 50 mL of 1 mol / L NaOH solution, and then 6.6 mL of 0.3 mol / L ferrous sulfate solution was added to obtain a premixed solution; the premixed solution was stirred and reacted at 60° C. for 4 h to obtain a reaction solution; in this embodiment, the molar ratio of iron element (ferrous iron) in ferrous sulfate to iron element (ferric iron) in the polymetallic iron mineral was 1:2.

[0103] After the reaction is completed, the reaction liquid is sampled; after the sample liquid is filtered and separated, an alkaline separation liquid and a solid separation are obtained. The remaining reaction liquid is subjected to magnetic separation (magnetic separation), and the specific process of magnetic separation is: the magnetite particles in the reaction liquid are sucked by a magnetic bar, collected and freeze-dried to obtain a magnetite concentrate; the suspension obtained after magnetic separation is centrifuged to obtain an alkaline separation liquid and polymetallic tailings, and the mass of the polymetallic tailings is much smaller than that of the magnetite concentrate. In this embodiment, the obtained alkaline separation liquids are all colorless and transparent, indicating that there is almost no dissolution of iron elements.

[0104] Figure 8 is the XRD diagram of the solid isolate after filtration separation. Figure 8 It can be seen that the iron alum slag after pickling is successfully converted into magnetite with a good crystal form.

[0105] Fig. 9 This is a scanning electron microscope image of magnetite concentrate and polymetallic tailings. Fig. 9 It can be seen that magnetite concentrate not only has good magnetic separation properties, but can also be magnetically separated from polymetallic tailings; and the magnetite concentrate obtained after magnetic separation is mainly composed of small particles of magnetite.

[0106] As can be seen from Table 6, after magnetic separation, magnetite concentrate and polymetallic tailings are mainly obtained, thereby separating impurities in magnetite and enriching them in polymetallic tailings. The element analysis method in Table 6 is energy spectrum element quantitative analysis (SEM-EDS), and the element content is the mass proportion of the corresponding element in the solid sample. As can be seen from Table 6, the mass proportion of iron in magnetite concentrate is 61.00%.

[0107] Table 6: Analysis of element content in each substance (%)

[0108]

[0109]

[0110] Example 2

[0111] 0.746 g of a polymetallic iron mineral (needle iron slag after pickling, the same as in Comparative Example 2) was mixed with 50 mL of a 1 mol / L NaOH solution, and then 13.3 mL of a 0.3 mol / L ferrous sulfate solution was added to obtain a premixed solution; the premixed solution was stirred and reacted at 60° C. for 4 hours to obtain a reaction solution; in this embodiment, the molar ratio of the iron element (ferrous iron) in the ferrous sulfate to the iron element (ferric iron) in the polymetallic iron mineral was 1:2.

[0112] After the reaction is completed, the reaction liquid is sampled; the sample liquid is filtered and separated to obtain an alkaline separation liquid and a solid separation. The remaining reaction liquid is subjected to magnetic separation (magnetic separation), and the specific process of magnetic separation is: the magnetite particles in the reaction liquid are sucked by a magnetic bar, collected and freeze-dried to obtain a magnetite concentrate; the suspension obtained after magnetic separation is centrifuged to obtain an alkaline separation liquid and polymetallic tailings, and the mass of the polymetallic tailings is much smaller than that of the magnetite concentrate. In this embodiment, the obtained alkaline separation liquids are all colorless and transparent, indicating that there is almost no dissolution of iron elements.

[0113] Fig.10 is the XRD diagram of the solid isolate after filtration separation. Fig.10 It can be seen that the goethite slag (polymetallic iron mineral) after pickling is successfully converted into magnetite with good crystal form; that is, after the zinc sulfate and calcium sulfate in the goethite slag are removed by pickling, it can be successfully converted into magnetite.

[0114] Fig.11 This is a scanning electron microscope image of magnetite concentrate and polymetallic tailings. Fig.11 It can be seen that the magnetite concentrate was successfully obtained in this embodiment, and the magnetite concentrate can be magnetically separated from the polymetallic tailings.

[0115] It can be seen from Table 7 that after magnetic separation, magnetite concentrate and polymetallic tailings are mainly obtained, thereby separating impurities in magnetite and enriching them in polymetallic tailings. The element analysis method in Table 7 is energy spectrum element quantitative analysis (SEM-EDS), and the element content is the mass proportion of the corresponding element in the solid sample.

[0116] Table 7: Analysis of element content in each substance (%)

[0117]

[0118] The above technical solutions of the present invention are only preferred embodiments of the present invention, and the patent scope of the present invention is not limited thereto. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A multi-metal separation method based on magnetite, characterized in that: Includes steps: S1, providing a ferric iron mineral; the ferric iron mineral contains iron and other impurity metals; S2, performing an acid wash treatment on the ferric iron mineral to obtain a polymetallic iron mineral; The pickling treatment comprises: placing the trivalent iron mineral in an acid solution for first mixing, and performing solid-liquid separation after the first mixing to obtain a pickling solution and the polymetallic iron mineral; the pH of the acid solution is 1 to 3.5; S3, mixing an alkali solution and a ferrous solution into the polymetallic iron mineral to obtain a premixed solution; performing a second mixing on the premixed solution to obtain a reaction solution; the alkali solution contains an alkaline substance, and the concentration of the alkaline substance in the premixed solution is 0.5-1.2 mol / L; the molar ratio of the iron element in the ferrous solution to the iron element in the polymetallic iron mineral is 1:1.5-5; S4, performing magnetic separation on the reaction liquid to obtain magnetite concentrate and suspension; performing solid-liquid separation on the suspension to obtain alkaline separation liquid and polymetallic tailings.

2. The multi-metal separation method according to claim 1, characterized in that: The trivalent iron minerals include one or more of pyrite, goethite, ferrihydrite, and schrenkiolite; the other impurity metals include one or more of aluminum, manganese, calcium, zinc, and lead.

3. The multi-metal separation method according to claim 1, characterized in that: The first mixing is performed for 1 to 20 hours at a temperature of 15 to 60° C.; the second mixing is performed for 0.5 to 10 hours at a temperature of 30 to 100° C.

4. The multi-metal separation method according to claim 1, characterized in that: The acid solution includes one or more of a sulfuric acid solution, a hydrochloric acid solution, an acetic acid solution, and a nitric acid solution.

5. The multi-metal separation method according to claim 1, characterized in that: The alkaline substance includes one or more of sodium hydroxide and potassium hydroxide; the ferrous solution includes one or more of ferrous sulfate solution and ferrous chloride solution.

6. The multi-metal separation method according to claim 5, characterized in that: The alkaline solution includes the alkaline separation solution.

7. The multi-metal separation method according to claim 1, characterized in that: The polymetallic iron mineral accounts for 1 to 20 g / L in the premixed solution.

8. A method for preparing magnetite based on trivalent iron minerals, characterized in that: Includes steps: S01, providing a trivalent iron mineral; the trivalent iron mineral contains iron and other impurity metals; S02, performing an acid wash treatment on the ferric iron mineral to obtain a polymetallic iron mineral; The pickling treatment comprises: placing the trivalent iron mineral in an acid solution for first mixing, and performing solid-liquid separation after the first mixing to obtain a pickling solution and the polymetallic iron mineral; the pH of the acid solution is 1 to 3.5; S03, mixing an alkali solution and a ferrous solution into the polymetallic iron mineral to obtain a premixed solution; performing a second mixing on the premixed solution to obtain a reaction solution; the alkali solution contains an alkaline substance, and the concentration of the alkaline substance in the premixed solution is 0.5-1.2 mol / L; the molar ratio of the iron element in the ferrous solution to the iron element in the polymetallic iron mineral is 1:2-4; S04, separating the reaction liquid into solid and liquid to obtain an alkaline separation liquid and a solid separation containing magnetite.

9. A method for precipitation of iron from zinc leaching solution, characterized in that: include: The zinc leaching solution is subjected to iron precipitation treatment to obtain trivalent iron mineral; and then the trivalent iron mineral is treated by the multi-metal separation method according to any one of claims 1 to 7 to obtain magnetite concentrate and multi-metal tailings.

10. The iron precipitation method according to claim 9, characterized in that: Also includes: Before the iron precipitation treatment is carried out, the pickling solution is mixed into the zinc leaching solution.

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