A magnetite preparation method, a multi-metal separation method and an iron precipitation method for zinc leachate

Abstract

The present invention provides a magnetite preparation method, a multi-metal separation method, and an iron precipitation method for zinc leachate. The multi-metal separation method comprises the following steps: S1, providing a ferric iron mineral; S2, subjecting the ferric iron mineral to an acid wash treatment to obtain a multi-metal iron mineral; the acid wash treatment comprises: placing the ferric iron mineral in an acid solution for a first mixing step, and performing solid-liquid separation after the first mixing step to obtain an acid wash solution and the multi-metal iron mineral; S3, mixing an alkaline solution and a ferrous solution into the multi-metal iron mineral to obtain a premixed solution; performing a second mixing step on the premixed solution to obtain a reaction solution; S4, subjecting the reaction solution to magnetic separation to obtain a magnetite concentrate and a suspension; and performing solid-liquid separation on the suspension to obtain an alkaline separation solution and a multi-metal tailing. The present invention can obtain a magnetite concentrate having an iron content as high as 61% and a lower content of entrained impurity metals, and can separate the impurity metals in the ferric iron mineral into the multi-metal tailings.

Description

Technical Field

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

[0002] The hydrometallurgical zinc smelting process, which comprises a roasting-leaching-electrolysis process, produces 85% of zinc. The electrolysis stage is the key step in extracting zinc from solution to form metallic zinc. To ensure the smooth progress of the electrolysis process and the quality of the final zinc product, strict requirements are placed on the electrolyte's impurity content. A notable characteristic of zinc leachate is its high concentration of multiple elements. In addition to high concentrations of zinc and iron, it can also contain a variety of heavy metal impurities such as lead, copper, cobalt, and aluminum. Iron, as the primary impurity, can affect the subsequent electrolytic refining of zinc. Therefore, the leachate undergoes iron precipitation treatment to convert the iron into a precipitate, which is then separated into a solid-liquid separation to produce a de-ironified waste residue.

[0003] Iron removal slag primarily consists of ferroalite slag obtained from the natrona process, goethite slag obtained from the goethite process, and hematite slag obtained from the hematite process. These slags have low iron content, large slag volumes, and high levels of impure metals, and are therefore listed on the National List of Hazardous Wastes (hazardous waste codes 321-0005-48 and 321-007-48, respectively). Currently, there is no cost-effective method for their treatment and recovery. While the hematite process can theoretically achieve an iron content of 70%, the hematite process requires high temperature and pressure, placing high demands on equipment. Consequently, only a few companies possess this technology. Therefore, developing a simple and feasible zinc leachate treatment process to produce directly usable iron slag with reduced slag volume, higher iron content, and lower levels of impure metals is of great significance.

[0004] In view of this, it is necessary to provide a magnetite preparation method, a multi-metal separation method and an iron precipitation method for zinc leachate 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 leachate, aiming to solve the above-mentioned technical problem of how to obtain iron slag with a higher iron content and a 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 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 to 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 to 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 minerals include one or more of ferrocyanide, goethite, ferrihydrite, and schrenkierite; 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; and 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 ferric iron mineral; the ferric 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 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 to 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 to 4;

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

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

[0023] Furthermore, the method further comprises: before performing 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 magnetite ore, and can also obtain magnetite concentrate with a higher iron content and a lower content of entrained impurity metals based on specific iron slag (such as iron alum slag), and enrich the impurity metals of the ferric iron minerals into polymetallic tailings. The present invention first precipitates the iron ions in the wet zinc smelting leachate in the form of ferric iron minerals and acid-washes 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 the magnetite ore to be processed (magnetite before magnetic separation). After magnetic separation and solid-liquid separation, magnetite concentrate and polymetallic tailings are obtained. 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 to traditional source iron precipitation products, magnetite is the iron oxide with the highest iron content, making it an ideal raw material for ironmaking. This increased iron content reduces the amount of iron slag produced, thereby alleviating storage and transportation pressures. Furthermore, magnetite possesses strong magnetic properties and can be rapidly separated from liquid and other solid phases through magnetic separation, facilitating the separation and enrichment of iron phases and other impurity metals, thus improving the current generally poor settling performance of iron slag. Therefore, the magnetite method offers significant advantages over other iron precipitation methods and represents a highly promising new iron precipitation method capable of reducing and repurposing 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 following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0028] Figure 1 The X-ray diffraction patterns of the iron vitriol residue in Comparative Example 1 of the present invention before and after pickling are shown; "Before washing" refers to the iron vitriol residue (iron vitriol residue before pickling), and "After washing" refers to the polymetallic iron mineral (iron vitriol residue 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 This 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 the X-ray diffraction pattern 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 material (magnetite before magnetic separation) in Example 1 of the present invention; Jarosite refers to the magnetite before magnetic separation derived from ferroalite slag, and Transformed from washed waste refers to the magnetite before magnetic separation converted from ferroalite slag after acid washing;

[0036] Figure 9 This is a 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] Figure 10 is the X-ray diffraction pattern of the solid separated material (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 from goethite slag after acid washing;

[0038] Figure 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 objectives, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0040] The following will be combined with the accompanying 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 embodiments described 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 making any creative efforts are within the scope of protection of the present invention.

[0041] Moreover, 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 ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0042] When the embodiments provide numerical ranges, it should be understood that, unless otherwise specified in the present invention, both 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 those skilled in the art understand the prior art and the present invention, and any method, equipment and material of the prior art similar or equivalent to the methods, equipment and materials described in the embodiments of the present invention can also be used to implement 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 have certain fluctuations and experimental errors, which do not affect the understanding of the invention technology effects.

[0043] It should be noted that magnetite has a high iron content and can be quickly separated from the liquid phase and other solid phases through 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 concentrate, 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 can be derived from the iron precipitate slag produced by the precipitation of iron in the zinc leachate; the ferric iron mineral includes one or more of pyrite, goethite, ferrihydrite, and Schmidt's mineral, that is, the ferric iron mineral includes one or more of pyrite slag, goethite slag, ferrihydrite slag, and Schmidt's mineral slag; pyrite can be potassium / sodium / ammonia ferrite; 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 sodium ferrite, goethite, zinc sulfate, and zinc ferrite; and / or, the ferric iron mineral includes or is goethite slag, and the goethite slag contains goethite, sodium ferrite, 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 ferrocyanide 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%.

[0049] When the trivalent iron mineral is the goethite slag, through quantitative element analysis 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%.

[0050] S2, performing an acid wash treatment on the ferric iron mineral to obtain a polymetallic iron mineral; the acid wash treatment includes: 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, 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-to-volume ratio of the ferric 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 sulfuric acid solution, hydrochloric acid solution, acetic acid solution, and nitric acid solution; and 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 to 20 hours, and the first mixing may be performed at a temperature of 25 to 60°C.

[0053] S3, adding an alkaline 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.

[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 an alkaline substance, and the concentration of the alkaline substance in the premixed solution is 0.5-1.2 mol / L or 0.7-0.9 mol / L; the concentration of the alkaline substance 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 further 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 ferrous sulfate solution and 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, 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; the output of the polymetallic tailings is less than that of the magnetite concentrate.

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

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

[0062] 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 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 to 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 to 4.

[0064] S04, separating the reaction liquid into solid and liquid to obtain an alkaline separated liquid and a solid separated material 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 achieve resource utilization 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 ferric iron minerals after solid-liquid separation; then treating the ferric iron minerals using 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 to 50 g / L, and the concentration of zinc is 90 to 110 g / L. 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 wastewater discharge and achieve 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 of the pretreatment liquid can be 0.8-1.5:1) to obtain a pretreatment liquid; then the pH value of the pretreatment liquid is adjusted to 1.5±0.2; thereafter, the reaction is stirred at 90-97°C for 5-7h, and the ferric iron mineral is obtained by solid-liquid separation, wherein the ferric iron mineral includes pyrite alum slag.

[0069] Alternatively, the pH value of the zinc leachate is adjusted to 4.0±0.2; thereafter, air is continuously introduced into the zinc leachate, 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, solid-liquid separation is performed to obtain the trivalent iron mineral, which 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 minerals containing multiple metals are mixed with an alkaline solution, and then a ferrous solution is added to convert the iron-containing minerals to obtain magnetite ore to be processed, and magnetite concentrate and polymetallic tailings are obtained by magnetic separation to separate impurities in the magnetite ore. Conventional iron precipitation products are mostly metastable iron-containing minerals. The present invention can transform them into magnetite that is more thermodynamically stable and has magnetic separation properties, 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. A zinc leachate was obtained by hot acid leaching (wet zinc smelting leachate). The elemental analysis results of the zinc leachate are shown in Table 1. The iron in the zinc leachate exists in the form of divalent iron. The elemental analysis method in Table 1 is ICP-OES, and the element content is the concentration of the corresponding element in the zinc leachate.

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

[0075]

[0076] 2. The zinc leachate is treated with iron precipitation to obtain iron alum residue (yellow iron alum residue); the iron precipitation process is: using H2O2 to remove Fe 2+ All oxidized to Fe 3+ , among which, the amount of H2O2 substance is related to 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 residue.

[0077] 3. Take 1 g of the iron alum residue obtained by precipitating iron in the zinc leachate, mix it with 40 mL of 0.11 mol / L (pH = 3) acetic acid solution, shake it at room temperature for 16 hours (acid washing), and then perform solid-liquid separation to obtain an acid washing solution and polymetallic iron minerals; the iron content in the acid washing 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 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 As can be seen from Table 2, the roton slag has a complex morphology and uneven particle size. It is composed of a mixture of roton, zinc sulfate, lead sulfate, and other particles, which are interwoven. The elemental analysis method in Table 2 is selected-point energy dispersive spectrometry (SEM-EDS), and the element content is the mass percentage 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] As can be seen from Table 3, the content of the impurity element zinc in the iron alum slag decreased from 18.9% to 9.21% before and after pickling. The element analysis method in Table 3 is quantitative element analysis by X-ray fluorescence spectroscopy, and the element content is the mass percentage of the corresponding element in the solid sample.

[0083] Table 3: X-ray fluorescence spectroscopy elemental 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 ferroalloy, the effect of removing other impurity elements is not obvious. The ferroalloy slag (polymetallic iron mineral) after pickling still contains a variety of impurity metals and needs further treatment.

[0086] Comparative Example 2

[0087] 1. The zinc leachate (same as Comparative Example 1) was subjected to iron precipitation treatment to obtain goethite slag; the iron precipitation treatment process was 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 was around 4.0, and obtaining goethite slag by solid-liquid separation after the reaction.

[0088] 2. Take 1 g of 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 hours (acid washing), and then perform solid-liquid separation to obtain an acid washing solution and polymetallic iron minerals; the iron content in the acid washing 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 precipitation of iron in zinc leaching solution is poor; the main components of the goethite slag are goethite, natantrite, 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 primarily composed of large, elongated calcium sulfate particles and small goethite agglomerates. The elemental analysis method in Table 4 is selected-point energy dispersive spectrometry (SEM-EDS), and the element contents are the mass percentages of the corresponding elements in the selected elements.

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

[0092]

[0093] As shown in Table 5, after pickling, the iron content of goethite increased from 31.6% to 59.9%, while the impurity contents of 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 remained unchanged before and after pickling, and even showed signs of increasing. The elemental analysis method in Table 5 is quantitative X-ray fluorescence analysis, and the element contents are the mass percentages of the corresponding elements in the solid sample.

[0094] Table 5: X-ray fluorescence spectrometry elemental 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, making the goethite slag difficult to handle and environmentally harmful.

[0097] Comparative Example 3

[0098] 0.746 g of goethite slag (same as Comparative Example 2) was mixed with 50 mL of 1 mol / L NaOH solution, and then 13.3 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.

[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 subjected to XRD analysis. 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 (aluminum slag after pickling, the same as in Comparative Example 1) was mixed with 50 mL of 1 mol / L NaOH solution, and 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 hours 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; the sample liquid is filtered and separated to obtain an alkaline separated liquid and a solid separated product. The remaining reaction liquid is subjected to magnetic separation (magnetic separation). The specific process of magnetic separation is: using a magnetic bar to absorb the magnetite particles in the reaction liquid, collecting and freeze-drying to obtain a magnetite concentrate; the suspension obtained after magnetic separation is centrifuged to obtain an alkaline separated liquid and polymetallic tailings, the mass of which is much smaller than that of the magnetite concentrate. In this embodiment, the obtained alkaline separated liquids are all colorless and transparent, indicating that almost no iron element is dissolved.

[0104] Figure 8 is the XRD pattern 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] Figure 9 This is a scanning electron microscope image of magnetite concentrate and polymetallic tailings. Figure 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 shown in Table 6, magnetic separation primarily yields magnetite concentrate and polymetallic tailings, effectively separating impurities from the magnetite and concentrating them in the polymetallic tailings. The elemental analysis method in Table 6 is energy-dispersive elemental analysis (SEM-EDS), and the element contents are expressed as the mass percentage of the corresponding element in the solid sample. As shown in Table 6, iron accounts for 61.00% by mass of the magnetite concentrate.

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

[0108]

[0109]

[0110] Example 2

[0111] 0.746 g of polymetallic iron mineral (needle iron slag after pickling, the same as in Comparative Example 2) was mixed with 50 mL of 1 mol / L NaOH solution, and 13.3 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 hours 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.

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

[0113] Figure 10 is the XRD pattern of the solid isolate after filtration separation. Figure 10 It can be seen that the goethite slag (polymetallic iron mineral) after pickling is smoothly 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 smoothly converted into magnetite.

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

[0115] As shown in Table 7, magnetic separation primarily yields magnetite concentrate and polymetallic tailings, thereby separating impurities from the magnetite and concentrating them in the polymetallic tailings. The elemental analysis method in Table 7 is energy dispersive elemental analysis (SEM-EDS), and the element contents are expressed as the mass percentage 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 do not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention's description 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: Including 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 includes: 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 to 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 to 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 ferrocyanide, goethite, ferrihydrite, and schrenkierite; and 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 sulfuric acid solution, hydrochloric acid solution, acetic acid solution, and 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 proportion of the polymetallic iron mineral in the premixed liquid is 1 to 20 g / L.

8. A method for preparing magnetite based on trivalent iron minerals, characterized in that: Including steps: S01, providing a ferric iron mineral; the ferric 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 includes: 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 to 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 to 4; S04, separating the reaction liquid into solid and liquid to obtain an alkaline separated liquid and a solid separated material containing magnetite.

9. A method for precipitation of iron in zinc leaching solution, characterized in that: include: The zinc leachate 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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