Method for strengthening hot melting separation of sulfur from metal sulfur residue by pretreatment

Abstract

The application discloses a method for strengthening sulfur hot melting filtration separation through pretreatment of metal sulfur residue, and comprises the following steps: 1) after crushing and grinding the metal sulfur residue, water and acid are added for pulp preparation to obtain a metal sulfur residue slurry; 2) after aeration treatment of the metal sulfur residue slurry, a decontamination regulator is added for decontamination to obtain a leaching solution; the decontamination regulator comprises iron sulfate, sodium chloride and ammonium chloride; 3) the leaching solution is filtered to separate a solid product, and the solid product is washed and dehydrated, and then sulfur liquid is separated through hot melting filtration; the method can realize viscosity reduction of the molten metal sulfur residue, so that the sulfur recovery rate in the hot melting filtration process of the metal sulfur residue is improved.

Description

Technical Field

[0001] This invention relates to a method for treating metallic sulfur slag, and particularly to a method for pretreatment of metallic sulfur slag to enhance sulfur thermal melting and separation, belonging to the field of comprehensive recycling of non-ferrous metal smelting waste. Background Technology

[0002] Zinc smelting processes are divided into pyrometallurgical and hydrometallurgical methods. Pyrometallurgical zinc smelting suffers from high energy consumption and the production of harmful gases, while hydrometallurgical zinc smelting has relatively lower energy consumption per unit, is more environmentally friendly, and has a higher degree of resource utilization. Currently, hydrometallurgical zinc smelting has become the mainstream of zinc metallurgical technology development, accounting for more than 80% of the world's total zinc production. In the oxygen pressure leaching hydrometallurgical zinc smelting process of zinc sulfide concentrate, most of the sulfur enters the acid leaching residue in the form of elemental sulfur, with a small amount existing in the form of sulfides, sulfates, or sulfate double salts. In addition to sulfur, the acid leaching residue often contains valuable metals such as zinc, iron, silicon, and silver, which have high recovery value. If these polymetallic sulfur slags are not treated and recovered in a timely manner, it will cause a great waste of resources and also lead to environmental problems caused by waste slag accumulation.

[0003] There are many methods for recovering elemental sulfur from sulfur slag, including chemical and physical methods. Chemical methods involve adding organic / inorganic solvents to dissolve sulfur, followed by extraction and processing to obtain sulfur products. However, the solvents used have problems such as toxicity and volatility, making them unsuitable for large-scale production. Physical methods mainly include vacuum distillation, high-pressure decanting, flotation, and hot filtration. Vacuum distillation and high-pressure decanting require expensive equipment and are complex processes, making them unsuitable for large-scale production. Flotation utilizes the difference in hydrophilicity of substances in the slag to separate elemental sulfur from other materials; the process is simple. Hot filtration utilizes the low melting point of sulfur, heating polymetallic sulfur slag to a certain temperature (130–160°C) and filtering to separate sulfur from other elements. This method is low-cost, and the higher the sulfur content in the slag, the better the hot filtration separation effect. It has significant advantages in treating sulfur-containing materials in actual production. Currently, domestic companies such as Chihong Zinc & Germanium, Zhongjin Lingnan, and Western Mining use the flotation-hot filtration method to treat polymetallic sulfur slag.

[0004] However, polymetallic sulfur slag, due to its complex composition and high viscosity after direct melting, is difficult to separate from other materials during hot filtration, resulting in low sulfur separation and recovery rates and hindering further separation and recovery of valuable metals in the filter cake. Current research focuses more on improving the melting process and less on raw material pretreatment. Therefore, it is necessary to provide a method for enhancing sulfur hot-melt filtration separation through pretreatment of metallic sulfur slag to address or at least alleviate the technical shortcomings of existing technologies in separating sulfur from metallic impurities. Summary of the Invention

[0005] In view of the defects existing in the treatment process of polymetallic sulfur slag in the prior art, the purpose of this invention is to provide a method for pretreatment of metal sulfur slag to enhance sulfur hot melt filtration separation. This method can reduce the viscosity of molten metal sulfur slag, thereby improving the sulfur recovery rate during the hot melt filtration process of metal sulfur slag. Moreover, the operation process is simple, avoids the addition of toxic reagents, and is conducive to industrial production.

[0006] To achieve the above technical objectives, the present invention provides a method for enhanced sulfur hot-melt filtration separation through pretreatment of metallic sulfur slag, the method comprising the following steps:

[0007] 1) After crushing and grinding the metallic sulfur slag, water and acid are added to make a slurry to obtain metallic sulfur slag slurry;

[0008] 2) After aeration treatment of the metallic sulfur slag slurry, a purification regulator is added to remove impurities, resulting in a leaching solution; the purification regulator includes ferric sulfate, sodium chloride, and ammonium chloride;

[0009] 3) The leachate solution is filtered to separate the solid product. After washing and dehydration, the solid product is separated into sulfur liquid by hot melt filtration.

[0010] The key to this invention is a special pretreatment process for metal sulfur slag, which efficiently removes impurity metal ions from the metal ions, thereby effectively reducing the viscosity of the molten metal sulfur slag, improving the hot-melt filtration effect, and increasing sulfur recovery efficiency. More specifically, acid is first used to adjust the slurry, and oxygen is introduced to oxidize and leach some metals and metal salts. Based on this, a special impurity removal regulator is used to convert difficult-to-leach impurity metal sulfides (such as zinc sulfide) into soluble compounds through a chemical reaction, thus achieving deep removal of metal impurities. The special impurity removal regulator used in this invention includes ferric sulfate, sodium chloride, and ammonium chloride. Ferric sulfate mainly provides iron ions to induce the formation of soluble zinc salts from insoluble metal sulfides such as zinc sulfide, while sodium chloride and ammonium chloride mainly provide chloride and ammonium ions, which promote the reaction between iron ions and insoluble metal sulfides, synergistically accelerating the process.

[0011] As a preferred embodiment, the metallic sulfur slag is ground to a particle size ≤106μm. Grinding the metallic sulfur slag to an appropriate particle size facilitates the dissolution of impurities.

[0012] As a preferred embodiment, the solid-liquid mass ratio of the metal sulfur slag slurry is 1:2 to 1:5, and the pH is 1 to 3. The pH can be adjusted using dilute sulfuric acid.

[0013] As a preferred embodiment, the aeration employs a stirring-assisted blower aeration method, with a stirring rate of 300–700 rpm and a duration of 0.5–2 hours. The temperature is room temperature, for example, 20–35°C. The gas used for aeration is air or other oxygen-containing gases.

[0014] As a preferred embodiment, the impurity removal regulator comprises the following components by mass percentage: 20-80% ferric sulfate, 2-20% sodium chloride, and 10-60% ammonium chloride. Ferric sulfate is the main component of the impurity removal regulator, primarily providing soluble iron ions to induce the formation of soluble zinc salts from insoluble metal sulfides such as zinc sulfide. Chloride and ammonium ions serve as secondary components to synergistically accelerate the reaction process.

[0015] As a preferred embodiment, the amount of the impurity removal regulator is measured to be 0.1 to 0.6 M of the total concentration of iron ions, chloride ions and ammonium ions in the metal sulfur slag slurry.

[0016] As a preferred embodiment, the conditions for impurity removal are: reaction at room temperature for 10 to 24 hours.

[0017] As a preferred embodiment, in the hot melt filtration process, the melting temperature is 140-150℃, the duration is 60-180 min, and the filtration pressure is 0.6-0.8 MPa.

[0018] As a preferred embodiment, the metal sulfur slag contains at least one of the impurity metal elements such as Fe, Zn, and Pb. More specifically, the metal sulfur slag contains ≥55wt% sulfur, ≤10wt% zinc, ≤20wt% iron, and ≤3wt% lead.

[0019] As a preferred embodiment, the washing process employs a multi-stage washing method, washing until the washing solution is neutral. More specifically, the washing process includes: filtering the leachate, washing the filter residue with deionized water by stirring, and filtering again until the filtrate has a neutral pH.

[0020] As a preferred embodiment, the dehydration is carried out to a moisture content of <10%. More specifically, the dehydration process includes: using a belt dewatering machine to dehydrate the metal sulfur slag after the water washing treatment, so that the moisture content of the metal sulfur slag is <10 wt%.

[0021] As a preferred embodiment, the sulfur liquid is granulated to obtain a sulfur product.

[0022] Compared with the prior art, the beneficial technical effects of the technical solution of the present invention are as follows:

[0023] This invention effectively removes impurities from metal sulfur slag by acid washing and aeration treatment combined with the use of regulating reagents, thereby reducing the viscosity of molten metal sulfur slag and effectively improving the sulfur separation and recovery rate.

[0024] The method for pretreatment of metallic sulfur slag and enhanced sulfur hot melt filtration separation provided by this invention has a simple operation process, avoids the use of toxic reagents, and is conducive to industrial application. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content shown in these drawings without creative effort.

[0026] Figure 1 This is a schematic flowchart of the method for enhancing sulfur hot-melt filtration separation through pretreatment of metallic sulfur slag in this invention.

[0027] Figure 2 The graph shows the viscosity and separation rate of polymetallic sulfur slag after pretreatment. Detailed Implementation

[0028] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0030] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of this invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to those described, used, or made of materials in the embodiments of this invention.

[0031] The following provides a further detailed explanation of the invention. The method for enhanced sulfur hot-melt filtration separation in the pretreatment of metallic sulfur slag provided by the present invention includes the following steps:

[0032] (1) The metallic sulfur slag is crushed and ground to a size ≤106μm; the sulfur content in the metallic sulfur slag is ≥55wt%; the zinc content is ≤10wt%; the iron content is ≤20wt%; the lead content is ≤3wt%; the size of the polymetallic sulfur slag is ≤106μm, specifically 1.3~106μm. It should be noted that the metallic sulfur slag can be polymetallic sulfur slag, that is, the metallic impurities can be multiple; the metallic impurities can contain heavy metal elements, that is, the metallic elements in the metallic impurities can include or be heavy metal elements, and the heavy metal elements can also be multiple; the heavy metal elements can include or be one or more of Zn and Pb; of course, the heavy metal elements can also include or be other heavy metal elements such as Hg and Cu, which are not listed here.

[0033] In this invention, the sulfur (S) in the metal sulfur slag refers to sulfur element existing in the form of S8. Fe exists in the form of FeS2, Zn exists in the form of ZnS, and Pb exists in the form of PbSO4. In addition to the above substances, the metal sulfur slag may also generally contain CaSO4. By mass fraction, the metal sulfur slag comprises: sulfur (S) ≥ 55%, Fe ≤ 20%, Zn ≤ 10%, and Pb ≤ 3%. Specifically, the S content can be 55%–85%, the Fe content can be 1%–20%, the Zn content can be 1%–10%, and the Pb content can be 0.1%–3%. It should be emphasized that since the sulfur element in substances containing S such as FeS2, ZnS, PbSO4, and CaSO4 does not exist in the form of sulfur, it can be disregarded in the percentage of sulfur (S).

[0034] (2) The metal sulfur slag obtained in step (1) is mixed with water, and the mass ratio of metal sulfur slag to water is 1:2 to 1:5; and the pH is adjusted to 1 to 3 with dilute sulfuric acid.

[0035] (3) The slurry obtained in step (2) is stirred (500 rpm) and aerated for 0.5 to 2 hours; the ambient temperature for aeration of the metal sulfur slag is 20 to 35°C and the time is 0.5 to 2 hours, while stirring at a speed of 500 rpm.

[0036] (4) The slurry obtained in step (3) is stopped from aeration under continuous stirring, and a regulating agent is added to prepare the leaching solution. The reaction is carried out at room temperature for 10 to 24 hours. The regulating agent includes ferric sulfate, sodium chloride and ammonium chloride. By mass fraction, the composition ratio is 20 to 80% ferric sulfate, 2 to 20% sodium chloride and 10 to 60% ammonium chloride, with a total concentration of ferric ions and ammonium ions of 0.1 to 0.6 M.

[0037] (5) The slurry obtained in step (4) is filtered and washed multiple times until the pH is neutral, and then vacuum dried until the moisture content is <10%. The water washing treatment is a conventional method, which only requires washing the metal sulfur slag to neutral or near-neutral pH, and will not be described in detail here. The dewatering treatment includes: dewatering the metal sulfur slag after the water washing treatment so that the moisture content of the metal sulfur slag is <10%.

[0038] Specifically, the process can be as follows: the metal sulfur slag after the water washing treatment is filtered and dehydrated through a vacuum belt filter to obtain dehydrated sulfur slag with a moisture content of <10%.

[0039] (6) The metal sulfur slag obtained in step (5) is heated to 140-150°C to melt, and the molten slag to be separated is filtered to obtain the separated sulfur liquid, which contains sulfur.

[0040] The melting temperature can be 140–150℃, and the melting time can be 60–180 min.

[0041] Specifically, the process involves: feeding the dehydrated metallic sulfur slag into a crude sulfur melting hydrocyclone via a belt conveyor. The temperature inside the hydrocyclone is maintained at 140–150°C for 60–180 minutes to ensure complete melting of the metallic sulfur slag. After melting, the molten slag is filtered to obtain metallic filter residue and separated sulfur liquid. The sulfur liquid is then granulated to obtain the sulfur product. The metallic filter residue (also known as heavy metal filter residue) contains metallic elements (metallic impurities) and may also contain other impurities; the sulfur liquid mainly contains sulfur.

[0042] The filter diameter for the filtration separation can be <10μm, specifically 1-8μm; the filtration separation can be pressure filtration, that is, during the filtration separation process, a pressure of 0.6-0.8MPa can be applied to the residue to be separated; during the filtration separation process, the temperature of the residue to be separated can be maintained at 140-150℃, or it can be filtered while hot.

[0043] The specific steps for filtering and separating the molten residue to be separated can be as follows: pumping the molten residue to be separated into a filter press or pumping it into a filter press in batches; then, sending the sulfur liquid (high-purity sulfur liquid) obtained by filter pressing into a granulator to granulate it into sulfur products, and then packaging and storing it.

[0044] It should be noted that, addressing the challenges of high viscosity in molten polymetallic sulfur slag and low efficiency in hot-melt filtration for sulfur recovery, this invention further removes certain metallic impurities from the polymetallic sulfur slag through pretreatment, reducing the degree of sulfur polymerization in the molten polymetallic sulfur slag and thus improving the sulfur hot-filtration separation and recovery rate. The method provided by this invention is simple and easy to operate, requiring no addition of toxic or harmful chemical reagents. It not only improves the sulfur resource recovery rate from polymetallic sulfur slag, increasing economic benefits, but also reduces the environmental risks associated with sulfur slag.

[0045] Specifically, the present invention first crushes and grinds polymetallic sulfur slag, dissolves it in deionized water, and adjusts the pH to 1-3 with concentrated sulfuric acid; then, the obtained slurry is stirred (500 rpm) and aerated with forced air for 0.5-2 hours; after aeration, a regulating reagent is added to prepare a leaching solution, and the reaction is carried out at room temperature for 10-24 hours; the obtained slurry is filtered and washed multiple times until the pH is neutral, and vacuum dried until the water content is <10%; the dehydrated metallic sulfur slag is sent to a melting hydrocyclone, and the temperature is maintained at 140-150°C in the crude sulfur melting hydrocyclone; finally, the molten slag to be separated is filtered and separated, and the high-purity sulfur product is obtained after cooling the filtrate or granulation.

[0046] The technical solutions provided by the present invention will be described in detail below with reference to specific embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0047] Example 1

[0048] A method for enhancing sulfur hot-melt filtration separation through pretreatment of metallic sulfur slag includes the following steps:

[0049] The polymetallic sulfur slag (main components: S 80wt%, Zn 3.5wt%, Fe 4wt%, Pb 0.35wt%, others 12.15wt%) was crushed, ground, and sieved (200 mesh). Deionized water was added to the polymetallic sulfur slag at a mass ratio of 2:1, and the pH was adjusted to 1.5 with sulfuric acid. Under stirring (500 rpm), the mixture was aerated using an air pump for 1 hour. Then, adjusting reagent A (including ferric sulfate, sodium chloride, and ammonium chloride, Fe) was added. 3+ Chloride ions and NH4+ +The total concentration was 0.4 M, and the composition (by mass fraction) was 70% ferric sulfate, 10% sodium chloride, and 20% ammonium chloride. The reaction was carried out at room temperature and pressure for 16 hours. The resulting slurry was filtered and washed multiple times until pH=7, then vacuum dried to a moisture content of 8%. The dehydrated metallic sulfur slag was fed into a melting hydrocyclone. The temperature was maintained at 150℃ for 30 minutes in the crude sulfur melting hydrocyclone. The molten sulfur (molten polymetallic sulfur slag) was then discharged from the bottom of the crude sulfur hydrocyclone into a stirred crude sulfur tank, with a measured viscosity of 1240 mPa·s. Subsequently, the molten sulfur slag (molten residue to be separated) was pumped into a hot filter (150℃) for filtration (pressure 0.6 MPa, filter diameter 8 μm), yielding metallic filter residue and high-purity sulfur liquid. The high-purity sulfur liquid was granulated and packaged to obtain the sulfur product.

[0050] In this embodiment, the sulfur purity in the sulfur product is 99.51%, the sulfur separation and recovery rate in the polymetallic sulfur slag is 65.70%, and the heavy metals in the metal filter residue can be further recovered.

[0051] Comparative Example 1

[0052] Compared to Example 1, the polymetallic sulfur slag in this comparative example did not undergo pretreatment.

[0053] Specifically, the untreated polymetallic sulfur slag was vacuum dried to a moisture content of 8% and fed into a melting hydrocyclone. The temperature was maintained at 150°C for 30 minutes in the coarse sulfur melting hydrocyclone. The molten sulfur (molten polymetallic sulfur slag) was then discharged from the bottom of the coarse sulfur hydrocyclone into a stirred coarse sulfur pool, with a measured viscosity of 2660 mPa·s. Subsequently, the molten sulfur slag (molten residue to be separated) was pumped into a hot filter (150°C) for filtration (pressure 0.6 MPa, filter diameter 8 μm), yielding metallic filter residue and high-purity sulfur liquid. The high-purity sulfur liquid was granulated and packaged to obtain the sulfur product.

[0054] In this comparative example, the purity of sulfur in the sulfur product was 99.21%, and the sulfur separation and recovery rate in the polymetallic sulfur slag was 53%.

[0055] Comparative Example 2

[0056] Compared to Example 1, this comparative example omits the acid addition and pH adjustment and aeration steps in the pretreatment process.

[0057] Specifically, the polymetallic sulfur slag (main components: S 80wt%, Zn 3.5wt%, Fe 4wt%, Pb 0.35wt%, others 12.15wt%) is crushed, ground, and sieved (200 mesh). Deionized water is added to the polymetallic sulfur slag at a mass ratio of 2:1. Under stirring (500 rpm), regulating agents (including ferric sulfate, sodium chloride, and ammonium chloride, Fe) are added. 3+ Chloride ions and NH4++ The total concentration was 0.4 M, and the composition (by mass fraction) was 70% ferric sulfate, 10% sodium chloride, and 20% ammonium chloride. The reaction was carried out at room temperature and pressure for 16 hours. The residue was filtered and vacuum dried to a moisture content of 8%. The dehydrated metallic sulfur slag was then fed into a melting hydrocyclone. The temperature was maintained at 150°C for 30 minutes in the crude sulfur melting hydrocyclone. The molten sulfur (molten polymetallic sulfur slag) was then discharged from the bottom of the crude sulfur hydrocyclone into a stirred crude sulfur pool, with a measured viscosity of 1372 mPa·s. Subsequently, the molten sulfur slag (molten residue to be separated) was pumped into a hot filter (150°C) for filtration (pressure 0.6 MPa, filter diameter 8 μm), yielding metallic filter residue and high-purity sulfur liquid. The high-purity sulfur liquid was granulated and packaged to obtain the sulfur product.

[0058] In this comparative example, the sulfur purity in the sulfur product was 99.22%, the sulfur separation and recovery rate in the polymetallic sulfur slag was 58.4%, and the heavy metals in the metal filter residue could be further recovered.

[0059] Comparative Example 3

[0060] Compared to Example 1, no regulatory reagents were added during the pretreatment process in this comparative example.

[0061] Specifically, the polymetallic sulfur slag (main components: S 80wt%, Zn 3.5wt%, Fe 4wt%, Pb 0.35wt%, others 12.15wt%) was crushed, ground, and sieved (200 mesh). Deionized water was added to the polymetallic sulfur slag at a mass ratio of 2:1, and the pH was adjusted to 1.5 with sulfuric acid. Under stirring (500 rpm), the mixture was aerated for 1 hour using an air pump. The resulting slurry was filtered and washed multiple times until the pH reached 7. It was then vacuum dried until the moisture content was 8%. The dehydrated polymetallic sulfur slag was fed into a melting hydrocyclone. The temperature was maintained at 150℃ in the coarse sulfur melting hydrocyclone for 30 minutes. The molten sulfur (molten polymetallic sulfur slag) was then discharged from the bottom of the coarse sulfur hydrocyclone into a coarse sulfur pool with stirring. The viscosity was measured to be 1410 mPa·s. The molten sulfur slag (molten slag to be separated) is then pumped into a hot filter (150°C) for filtration (pressure 0.6MPa, filter diameter 8μm) to obtain metal filter residue and high-purity sulfur liquid; the high-purity sulfur liquid is then granulated and packaged to obtain sulfur products.

[0062] In this comparative example, the sulfur purity in the sulfur product was 99.33%, the sulfur separation and recovery rate in the polymetallic sulfur slag was 55.7%, and the heavy metals in the metal filter residue could be further recovered.

[0063] Comparative Example 4

[0064] Compared to Example 1, this comparative example only contains one of the regulatory reagents added during the pretreatment process.

[0065] Specifically, the polymetallic sulfur slag (main components: S 80wt%, Zn 3.5wt%, Fe 4wt%, Pb 0.35wt%, others 12.15wt%) is crushed, ground, and sieved (200 mesh). Deionized water is added to the polymetallic sulfur slag at a mass ratio of 2:1. Under stirring (500 rpm), a regulating agent (ferric sulfate, Fe3+) is added. + The concentration was 0.4M (the composition ratio of ferric sulfate was 100% by mass), and the reaction was carried out at room temperature and pressure for 16 hours. The residue was filtered and vacuum dried to a moisture content of 8%. The dehydrated metallic sulfur slag was then fed into a melting hydrocyclone. The temperature was maintained at 150℃ for 30 minutes in the crude sulfur melting hydrocyclone. The molten sulfur (molten polymetallic sulfur slag) was then discharged from the bottom of the crude sulfur hydrocyclone into a stirred crude sulfur pool, and its viscosity was measured to be 1658 mPa·s. Subsequently, the molten sulfur slag (molten residue to be separated) was pumped into a hot filter (150℃ temperature) for filtration (pressure 0.6 MPa, filter diameter 8 μm), yielding metallic filter residue and high-purity sulfur liquid. The high-purity sulfur liquid was granulated and packaged to obtain the sulfur product.

[0066] In this comparative example, the sulfur purity in the sulfur product was 99.18%, the sulfur separation and recovery rate in the polymetallic sulfur slag was 58.89%, and the heavy metals in the metal filter residue could be further recovered.

[0067] Example 2

[0068] A method for enhancing sulfur hot-melt filtration separation through pretreatment of metallic sulfur slag includes the following steps:

[0069] The polymetallic sulfur slag (main components: S 82wt%, Zn 4.1wt%, Fe 3.8wt%, Pb 0.52wt%, others 9.58wt%) was crushed, ground, and sieved (200 mesh). Deionized water was added to the polymetallic sulfur slag at a mass ratio of 2:1, and the pH was adjusted to 1.5 with sulfuric acid. Under stirring (500 rpm), the mixture was aerated using an air pump for 1 hour. Then, adjusting reagent B (including ferric sulfate, sodium chloride, and ammonium chloride, Fe) was added. 3+ Chloride ions and NH4+ +The total concentration was 0.3M, and the composition (by mass fraction) was 60% ferric sulfate, 10% sodium chloride, and 30% ammonium chloride. The reaction was carried out at room temperature and pressure for 16 hours. The resulting slurry was filtered and washed multiple times until pH=7, then vacuum dried to a moisture content of 10%. The dehydrated metallic sulfur slag was fed into a melting hydrocyclone. The temperature was maintained at 150℃ for 30 minutes in the crude sulfur melting hydrocyclone. The molten sulfur (molten polymetallic sulfur slag) was then discharged from the bottom of the crude sulfur hydrocyclone into a stirred crude sulfur tank, with a measured viscosity of 1160 mPa·s. Subsequently, the molten sulfur slag (molten residue to be separated) was pumped into a hot filter (150℃) for filtration (pressure 0.6 MPa, filter diameter 8 μm), yielding metallic filter residue and high-purity sulfur liquid. The high-purity sulfur liquid was granulated and packaged to obtain the sulfur product.

[0070] In this embodiment, the sulfur purity in the sulfur product is 99.43%, the sulfur separation and recovery rate in the polymetallic sulfur slag is 66.1%, and the heavy metals in the metal filter residue can be further recovered.

[0071] Example 3

[0072] A method for enhancing sulfur hot-melt filtration separation through pretreatment of metallic sulfur slag includes the following steps:

[0073] The polymetallic sulfur slag (main components: S 77wt%, Zn 5.6wt%, Fe 6.4wt%, Pb 0.79wt%, other 10.21wt%) was crushed, ground, and sieved (200 mesh). Deionized water was added to the polymetallic sulfur slag at a mass ratio of 2:1, and the pH was adjusted to 2 with sulfuric acid. Under stirring (500 rpm), the mixture was aerated using an air pump for 1 hour. Then, adjusting reagent C (including ferric sulfate, sodium chloride, and ammonium chloride, Fe) was added. 3+ Chloride ions and NH4+ + The total concentration was 0.5M, and the composition (by mass fraction) was 40% ferric sulfate, 15% sodium chloride, and 45% ammonium chloride. The reaction was carried out at room temperature and pressure for 16 hours. The resulting slurry was filtered and washed multiple times until pH=7, then vacuum dried to a moisture content of 9%. The dehydrated metallic sulfur slag was fed into a melting hydrocyclone. The temperature was maintained at 150℃ for 30 minutes in the crude sulfur melting hydrocyclone. The molten sulfur (molten polymetallic sulfur slag) was then discharged from the bottom of the crude sulfur hydrocyclone into a stirred crude sulfur tank, with a measured viscosity of 1221 mPa·s. Subsequently, the molten sulfur slag (molten residue to be separated) was pumped into a hot filter (150℃) for filtration (pressure 0.6 MPa, filter diameter 8 μm), yielding metallic filter residue and high-purity sulfur liquid. The high-purity sulfur liquid was granulated and packaged to obtain the sulfur product.

[0074] In this embodiment, the sulfur purity in the sulfur product is 99.38%, the sulfur separation and recovery rate in the polymetallic sulfur slag is 64%, and the heavy metals in the metal filter residue can be further recovered.

[0075] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for pretreatment of metallic sulfur slag to enhance sulfur hot-melt filtration separation, characterized in that: Includes the following steps: 1) After crushing and grinding the metallic sulfur slag, water and acid are added to make a slurry to obtain metallic sulfur slag slurry; 2) After aeration treatment of the metallic sulfur slag slurry, a purification regulator is added to remove impurities, resulting in a leaching solution; the purification regulator includes ferric sulfate, sodium chloride, and ammonium chloride; 3) The leachate solution is filtered to separate the solid product. After washing and dehydration, the solid product is separated into sulfur liquid by hot melt filtration.

2. The method for pretreatment of metallic sulfur slag to enhance sulfur hot-melt filtration separation according to claim 1, characterized in that: The metallic sulfur slag is ground to a particle size of ≤106μm.

3. The method for pretreatment of metallic sulfur slag to enhance sulfur hot-melt filtration separation according to claim 1, characterized in that: The solid-liquid mass ratio of the metal sulfur slag slurry is 1:2 to 1:5, and the pH is 1 to 3.

4. The method for pretreatment of metallic sulfur slag to enhance sulfur hot-melt filtration separation according to claim 1, characterized in that: The aeration is achieved by stirring-assisted blower aeration, with a stirring rate of 300-700 rpm and an aeration time of 0.5-2 hours.

5. The method for pretreatment of metallic sulfur slag to enhance sulfur hot-melt filtration separation according to claim 1, characterized in that: The impurity removal regulator comprises the following components by mass percentage: ferric sulfate 20-80%, sodium chloride 2-20%, and ammonium chloride 10-60%.

6. A method for pretreatment of metallic sulfur slag to enhance sulfur hot-melt filtration separation according to claim 1 or 5, characterized in that: The amount of the impurity removal regulator is measured based on the total concentration of iron ions, chloride ions and ammonium ions in the metal sulfur slag slurry being 0.1 to 0.6 M.

7. A method for pretreatment of metallic sulfur slag to enhance sulfur hot-melt filtration separation according to claim 1 or 5, characterized in that: The conditions for impurity removal are: reaction at room temperature for 10 to 24 hours.

8. The method for pretreatment of metallic sulfur slag to enhance sulfur hot-melt filtration separation according to claim 1, characterized in that: During the hot melt filtration process, the melting temperature is 140-150℃, the duration is 60-180 min, and the filtration pressure is 0.6-0.8 MPa.

9. A method for pretreatment of metallic sulfur slag to enhance sulfur hot-melt filtration separation according to claim 1, 2, 3, 4, 5 or 8, characterized in that: The sulfur content in the metal sulfur slag is ≥55wt%, zinc content is ≤10wt%, iron content is ≤20wt%, and lead content is ≤3wt%.

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