A method for enhancing the filtration and separation of sulfur from metallic sulfur slag

Abstract

This invention discloses a method for enhancing the filtration and separation of sulfur in metallic sulfur slag. The method involves preparing the metallic sulfur slag into a slurry using acid, followed by sequential aeration, impurity removal (using impurity removal regulators including ferric sulfate, sodium chloride, and ammonium chloride), washing, dehydration, drying, and melting. A viscosity regulator (including thiazole and guanidine substances) is added to the molten metallic sulfur slag, and after stirring and reaction, the mixture is filtered to obtain a sulfur solution. This method reduces the viscosity of the molten metallic sulfur slag and improves the separation rate of sulfur from heavy metal impurities in the slag.

Description

Technical Field

[0001] This invention relates to a method for sulfur recovery from metallic sulfur slag, and particularly to a method for enhanced sulfur filtration and separation from metallic sulfur slag, belonging to the field of comprehensive recycling of non-ferrous metal smelting waste. Background Technology

[0002] In the non-ferrous smelting industry, a large amount of polymetallic sulfur slag is generated. The sulfur and heavy metal impurities in this slag are mixed and can be trapped and transported. Due to technological limitations, traditional methods mostly involve stockpiling to dispose of this type of polymetallic sulfur slag. However, because polymetallic sulfur slag has a high sulfur content and also contains a large amount of heavy metal ions, it is often classified as hazardous waste. Stockpiling polymetallic sulfur slag poses significant environmental risks, such as heavy metal pollution of soil, SO2 pollution, and serious environmental problems like acidic wastewater.

[0003] Currently, domestic and international methods for treating polymetallic sulfur slag are mainly divided into chemical and physical methods. Chemical methods involve dissolving and then precipitating sulfur to separate it from metallic impurities. However, the solvents used in chemical methods are toxic, flammable, and volatile, resulting in high solvent consumption and limiting their application to large-scale production. Physical methods mainly include vacuum distillation, high-pressure decanting, and hot-melt filtration. However, vacuum distillation and high-pressure decanting are too energy-intensive and costly. Therefore, the more mature method currently is hot-melt filtration to separate sulfur from metallic impurities. This method utilizes the fact that sulfur has a melting point of 120℃ and transforms into a liquid state at high temperatures. Pressure filtration is used to achieve solid-liquid separation, yielding sulfur products and hot-melt filter residue.

[0004] However, sulfur-containing waste residue contains a large amount of metallic impurities, such as Zn, which can induce a decrease in the SS bond energy of the cyclic octasulfur in liquid sulfur. This leads to ring-opening polymerization during high-temperature pressure filtration, forming large-molecule polymerized sulfur and increasing viscosity. Because of the high viscosity of the molten polymetallic sulfur residue, mass transfer resistance is high during pressure filtration, making it difficult to separate sulfur from metallic impurities. This not only affects the separation rate and purity of sulfur but also, due to the high sulfur content of the filter residue, generates a large amount of polluted acid after treatment, causing serious environmental pollution. It also makes the efficient recovery of valuable metals from the filter residue very difficult, leading many companies to choose stockpiling to dispose of such filter residue. Large-scale stockpiling of filter residue also brings new environmental pollution problems.

[0005] In view of this, it is necessary to provide a method for enhancing the filtration and separation of sulfur in metallic sulfur slag, so as to solve or at least alleviate the technical defects of the prior art in the difficulty of separating sulfur from metal impurities. Summary of the Invention

[0006] To address the technical challenges in existing technologies where metal impurities induce sulfur polymerization during the melting and heat preservation process of polymetallic sulfur slag, resulting in high viscosity and low sulfur-metal separation rate, the present invention aims to provide a method for enhancing sulfur filtration and separation in polymetallic sulfur slag. This method achieves viscosity reduction of molten polymetallic sulfur slag by enhancing metal impurity leaching and adding a special viscosity modifier, reducing the viscosity by more than 60%. This improves the separation rate of sulfur and heavy metal impurities in polymetallic sulfur slag, effectively reduces filter residue accumulation, and yields a high purity sulfur product (>99.5%).

[0007] To achieve the above-mentioned technical objectives, the present invention provides a method for enhancing the filtration and separation of sulfur in metallic sulfur slag. The method involves preparing the metallic sulfur slag into a slurry using acid, and then subjecting the resulting slurry to aeration, impurity removal, water washing, dehydration, drying, and melting treatment in sequence. After adding a viscosity modifier to the molten metallic sulfur slag and stirring the reaction, the slurry is filtered to obtain a sulfur liquid. The impurity removal process uses a viscosity modifier including ferric sulfate, sodium chloride, and ammonium chloride. The viscosity modifier contains thiazole and guanidine substances.

[0008] The key to the enhanced sulfur filtration and separation method in this invention for metallic sulfur slag lies in the following: Firstly, the metallic sulfur slag is treated with acid leaching, aeration, and impurity removal, which efficiently removes metallic impurities from the slag, thereby effectively reducing the viscosity of the molten metallic 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 impurities such as zinc sulfide (e.g., zinc sulfide) into soluble compounds through chemical reactions, thus achieving deep removal of metallic impurities. The impurity removal regulator 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. On the other hand, a special viscosity modifier was used to reduce the viscosity of the molten metallic sulfur slag, improve its filtration and separation effect, and increase the separation rate of sulfur and metallic impurities. The viscosity modifier used was mainly thiazole compounds, with a small amount of guanidine compounds. The thiazole groups in the thiazole compounds can reduce the bond energy of the S-S bonds in the polymerized sulfur, inducing chain scission and depolymerization. Simultaneously, the thiazole ring has a strong coordination effect on metal ions, reducing the interaction force between metal ions and sulfur molecules, which is beneficial for the separation of metallic impurities from sulfur. The guanidine compounds, as auxiliary materials, mainly play a stabilizing role during the depolymerization process of the polymerized sulfur, thus ensuring the viscosity-regulating effect of the thiazole compounds.

[0009] 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, primarily providing soluble iron ions to induce the formation of soluble zinc salts from sparingly soluble metal sulfides such as zinc sulfide. Chloride and ammonium ions are secondary components, synergistically accelerating the reaction process. The amount of the impurity removal regulator is 0.5-3 wt% of the mass of the metal sulfur slag.

[0010] As a preferred embodiment, the viscosity modifier comprises the following components by mass percentage: 90-98% thiazole compounds and 2-10% guanidine compounds. In the viscosity modifier of this invention, thiazole compounds are the main component. The five-membered ring group of thiazole can reduce the bond energy of the SS bond in polymeric sulfur, inducing chain scission and depolymerization. Simultaneously, the thiazole ring has a strong coordination effect on metal ions, reducing the interaction force between metal ions and sulfur molecules, which is beneficial for the separation of metal impurities in sulfur. Guanidine compounds serve as auxiliary components, stabilizing the viscosity modifier of the thiazole compounds. If the proportion of thiazole compounds relative to guanidine compounds is too low, it will be difficult to achieve the effects of viscosity reduction and improved separation of metal impurities; if the proportion of thiazole compounds relative to guanidine compounds is too high, it will be difficult to stabilize the viscosity modifier of the thiazole compounds.

[0011] As a preferred embodiment, the thiazole substance is at least one selected from 2-mercaptobenzothiazole, 2-amino-4-methylbenzothiazole, 2-aminobenzothiazole, and dibenzothiazole disulfide. Among the preferred thiazole substances, 2-mercaptobenzothiazole and dibenzothiazole disulfide can generate active sulfur free radicals at high temperatures in molten metallic sulfur slag, which can also induce the breaking of long-chain SS bonds and inhibit their polymerization to form large-molecule sulfur, achieving the effects of sulfur inhibition, polymerization suppression, and viscosity reduction.

[0012] As a preferred embodiment, the guanidine substance is diphenylguanidine.

[0013] As a preferred embodiment, the viscosity modifier comprises thiuram derivatives and / or sulfenamide derivatives. The mass dispersion of the thiuram derivatives in the viscosity modifier does not exceed 5%, and the mass fraction of the sulfenamide derivatives does not exceed 5%. The viscosity modifier of the present invention may also incorporate thiuram derivatives to provide active sulfur free radical components, thereby inducing SS bond breakage, achieving the effects of sulfur depletion and polymerization inhibition, and reducing viscosity. Simultaneously, a small amount of sulfenamide derivatives may be introduced as an auxiliary component to further stabilize the viscosity modifier of thiazole and thiuram derivatives. As a more preferred embodiment, the thiuram derivative is tetramethylthiuram disulfide and / or tetramethylthiuram monosulfide. As a more preferred embodiment, the sulfenamide derivative is N,N-dimethyl-2-benzothiazolyl sulfenamide.

[0014] As a preferred embodiment, the viscosity modifier is used at a concentration of 0.05–0.30 mol / kg of the metallic sulfur slag. More preferably, the concentration of the viscosity modifier is 0.10–0.20 mol / kg of the metallic sulfur slag. If the proportion of the viscosity modifier is too low, a large number of SS bonds will not break, resulting in poor viscosity reduction and depolymerization effects. If the proportion of the viscosity modifier is too high, a large number of active sulfur free radicals will undergo self-polymerization, affecting the activity of free radicals. Excessive amounts may even lead to their polymerization into large-molecule sulfur, having the opposite effect.

[0015] As a preferred embodiment, the stirring reaction is carried out at a temperature of 140–150°C for 20–60 minutes. Stirring facilitates the thorough mixing and reaction of the viscosity modifier with the molten sulfur slag. The preferred reaction temperature helps ensure the reactivity of the viscosity modifier, achieving better viscosity control.

[0016] As a preferred embodiment, the metallic sulfur slag contains sulfur, iron, and heavy metal elements. The heavy metal elements include at least one of Zn and Pb. The main components and their mass content in the metallic sulfur slag are: S > 55%, Fe < 20%, Zn < 10%, Pb < 3%.

[0017] As a preferred embodiment, the conditions for slurry preparation are: temperature of 45–100°C and pH of the acid solution of 1–4. Acid leaching can leach out metal ions, reducing their impact on the subsequent melting and hot pressing process.

[0018] As a preferred embodiment, the impurity removal conditions are: stirring rate of 150–350 rpm, temperature of 25–45°C, and time of 4–16 h. These preferred impurity removal conditions facilitate the conversion of sparingly soluble metal sulfides into soluble salts.

[0019] As a preferred embodiment, the moisture content of the dehydrated metallic sulfur slag is <12wt%.

[0020] As a preferred embodiment, the melting conditions are: a temperature of 150–155°C and a holding time of 30–200 min. A further preferred holding time is 60–180 min.

[0021] As a preferred embodiment, the pressure applied during the pressure filtration process is 0.6–0.8 MPa. The filter screen used in the pressure filtration has a filter diameter ≤0.5 μm.

[0022] As a preferred embodiment, the sulfur liquid is granulated to obtain a sulfur product.

[0023] Compared with the prior art, the technical solution of the present invention has at least the following advantages:

[0024] 1. To address the technical challenge of high viscosity and low separation rate of sulfur and metal caused by the polymerization of molten sulfur during the heat preservation process in the crude sulfur tank, this invention reduces the viscosity of molten metal sulfur slag by more than 60% by adding a special viscosity modifier. At the same time, it promotes the separation efficiency of sulfur and metal impurities, resulting in sulfur products with higher purity.

[0025] 2. This invention can improve the separation rate of sulfur and heavy metal impurities in metal sulfur slag, effectively reduce the accumulation of filter residue, and compared with the existing solvent method, this invention significantly reduces the cost of chemical solvents, avoids the use of highly toxic organic solvents, and recovers a high purity sulfur product (>99.5%). Attached Figure Description

[0026] 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.

[0027] Figure 1 This is a schematic flowchart of the method for enhancing the filtration and separation of sulfur in metallic sulfur slag according to the present invention.

[0028] Figure 2 The image shows the XRD patterns of the polymetallic sulfur slag (#1 polymetallic sulfur slag) and sulfur product (sulfur obtained after processing by this technology) in Example 1 of this invention.

[0029] Figure 3 To compare with the sulfur product obtained in Comparative Example 3. Detailed Implementation

[0030] The technical solutions of the present invention will now be clearly and completely described with reference to the accompanying drawings of the embodiments. 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.

[0031] 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.

[0032] 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.

[0033] Those skilled in the art should understand that non-ferrous metal sulfides are important sources of metal and sulfur resources. However, during mining and smelting, large amounts of pollutants containing various heavy metals such as lead, mercury, and copper are generated, causing significant environmental harm; among these, sulfur-containing heavy metal hazardous waste is particularly difficult to treat. Sulfur is easily oxidized, which may lead to equipment corrosion or SO2 pollution during subsequent treatment; furthermore, the binding forms of sulfur and heavy metal ions are diverse, posing significant challenges to the recovery of valuable metal ions and the separation of toxic metal ions. Therefore, resource recovery is an important means of treating and disposing of sulfur-containing heavy metal hazardous waste. When heavy metals are encapsulated in sulfur, how to separate the heavy metals from the sulfur is the key issue for achieving resource recovery and also a challenge faced in the treatment of sulfur-containing heavy metal hazardous waste.

[0034] Based on this, in order to effectively separate heavy metals (metal impurities) and sulfur in metal sulfur slag, the present invention provides a method for enhanced sulfur filtration and separation in metal sulfur slag, comprising the following steps:

[0035] S1 provides molten metal sulfur slag, which contains metal impurities (including metal elements) and sulfur (S).

[0036] It should be noted that the metal sulfur slag can be a polymetallic sulfur slag, that is, the metal elements in the metal impurities can be multiple; the metal impurities shown can contain heavy metal elements, that is, the metal elements in the metal impurities can include or be heavy metal elements, and there can be multiple heavy metal elements; 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 will not be listed here.

[0037] The sulfur (S) in the metal sulfur slag involved in this invention refers to the element S existing in the form of S8, the form of Fe includes or is FeS2, the form of Zn includes or is ZnS, and the form of Pb includes or is PbSO4; in addition to the above substances, the metal sulfur slag may also generally contain CaSO4.

[0038] The metallic sulfur slag, by mass fraction, comprises: sulfur (S) > 55%, Fe < 20%, Zn < 10%, and Pb < 3%. Specifically, the S content can be 55%–95%, the Fe content can be 5%–20%, the Zn content can be 2%–10%, and the Pb content can be 0.05%–3.00%.

[0039] It should be emphasized that since the sulfur element in sulfur-containing substances such as FeS2, ZnS, PbSO4, and CaSO4 does not exist in the form of sulfur, the proportion of sulfur (S) can be excluded from the calculation.

[0040] In this invention, the molten metal sulfur slag provided may include or be:

[0041] S11, the solid metal sulfur slag (before melting) is subjected to acid leaching, aeration, impurity removal, water washing and dehydration treatment in sequence.

[0042] Specifically, it includes:

[0043] Acid leaching treatment: The metallic sulfur slag is subjected to acid leaching at a temperature of 45–100°C, using an acid solution with a pH of 1–4. The acid solution may include at least one of dilute hydrochloric acid and dilute sulfuric acid, with the specific concentration determined by the pH. The acid leaching process effectively removes impurities from the polymetallic sulfur slag.

[0044] The leachate slurry is aerated: stirred and aerated for 0.5 to 2 hours; the ambient temperature for aeration of the metallic sulfur slag is 20 to 35°C, the time is 0.5 to 2 hours, and it is stirred at the same time at a rate of 400 to 600 rpm.

[0045] Impurity removal treatment: Prepare the leaching solution by adding a regulating agent, stirring at a speed of 150-350 rpm, at a temperature of 25-45℃, for a time of 4-16 h; the regulating agent includes ferric sulfate, sodium chloride and ammonium chloride, and by mass fraction, the composition ratio is 20-80% ferric sulfate, 2-20% sodium chloride and 10-60% ammonium chloride, and the amount of the impurity removal pretreatment regulating agent added is 0.5-3 wt%.

[0046] The water washing treatment is a conventional method, which only requires washing the metallic sulfur slag until it is neutral or close to neutral, and will not be described in detail here.

[0047] The dehydration treatment includes: dehydrating the metal sulfur slag that has undergone the water washing treatment to make the moisture content of the metal sulfur slag <12%.

[0048] 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 <12%.

[0049] S12, the dehydrated metallic sulfur slag is melted to obtain molten metallic sulfur slag; wherein the melting temperature can be 150-155℃, and the melting time can be 60-180 min.

[0050] Specifically, the process can be as follows: the dehydrated metallic sulfur slag is fed into a crude sulfur melting hydrocyclone via a belt conveyor. The temperature inside the crude sulfur melting hydrocyclone is 150-155°C, and the holding time inside the crude sulfur melting hydrocyclone is 60-180 minutes to ensure that the metallic sulfur slag is completely melted. After melting, the molten metallic sulfur slag is discharged from the bottom of the crude sulfur melting hydrocyclone into a crude sulfur pool for subsequent steps in step S2.

[0051] S2, a viscosity modifier is mixed into the molten metal sulfur slag to obtain a molten slag to be separated; the amount of the viscosity modifier added is 0.05 to 0.30 mol / kg of the metal sulfur slag.

[0052] The viscosity modifier, by mass fraction, comprises or consists of: 90-98% thiazoles, 0-5% thiurams, 2-10% guanidines, and 0-5% sulfenamides; the total mass fraction of the viscosity modifier is 100%.

[0053] The thiazoles may include or be 2-mercaptobenzothiazoles, the thiurams may include or be tetramethylthiurams disulfide, the guanidines may include or be diphenylguanidines, and the sulfenamides may include or be N,N-dimethyl-2-benzothiazole sulfenamides.

[0054] The process of mixing a viscosity modifier into the molten metal sulfur slag may include: adding the viscosity modifier into the molten metal sulfur slag, stirring at a temperature of 140–150°C, and maintaining the temperature for 20–60 minutes.

[0055] The addition of a viscosity modifier to the molten metal sulfur slag may further include: stirring the molten metal sulfur slag at a temperature of 140–150°C and holding it at that temperature for 30–200 min before adding the viscosity modifier to the molten metal sulfur slag.

[0056] The specific steps of mixing the viscosity modifier into the molten metal sulfur slag can be as follows: after the molten metal sulfur slag is discharged from the bottom of the crude sulfur melting hydrocyclone into the crude sulfur pool, it is stirred at a temperature of 140-150°C (stirring speed can be <500 rpm) and kept at this temperature for 20-60 min; then, a sulfur viscosity modifier is added, and the mixture is stirred at a temperature of 140-150°C (stirring speed can be <500 rpm) and kept at this temperature for 30-200 min to obtain viscosity-reducing sulfur slag (molten slag to be separated).

[0057] S3, the molten residue to be separated is filtered to obtain metal filter residue and separated sulfur liquid. Then, the sulfur liquid is granulated to obtain sulfur product. The metal filter residue (also called heavy metal filter residue) contains metal elements (metal impurities) and may also contain other impurities; the sulfur liquid mainly contains sulfur.

[0058] The filter diameter for the filtration separation can be ≤0.5μm, specifically 0.1~0.5μm; 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℃.

[0059] 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.

[0060] It should be noted that this invention addresses the challenges of high viscosity and low separation efficiency when separating sulfur and metal impurities from molten sulfur slag. It provides a method that uses a sulfur viscosity-regulating reagent to break down the long-chain polymerized sulfur molecules and inhibit their repolymerization, forming small-molecule cyclooctasulfides that are easily filtered and recovered. The method of this invention is simple, easy to operate, and has good processing results. It effectively reduces the viscosity of molten sulfur slag, achieving efficient separation and recovery of sulfur from heavy metals such as zinc and lead. It comprehensively utilizes valuable metals and sulfur resources in hazardous waste, resulting in high economic benefits.

[0061] Specifically, this invention first pre-treats the metallic sulfur slag with acid washing to remove impurities. After impurity removal, the metallic sulfur slag is washed with water until the pH value is neutral. Then, the metallic sulfur slag is dehydrated (moisture content <12%) and sent to a melting hydrocyclone. The temperature in the crude sulfur melting hydrocyclone is maintained at 150-155°C. After the metallic sulfur slag melts for 60-180 minutes, it is pumped into a crude sulfur tank and continuously heated and stirred. The temperature in the crude sulfur tank is maintained at 140-150°C while stirring. After heating and stirring for 30-200 minutes, a viscosity modifier is added and stirring and heating are continued for 20-60 minutes. During this process, the viscosity modifier breaks down the long-chain polymerized sulfur molecules to form small-molecule cyclic octasulfide, which is easier to filter, enhances the separation of sulfur from metal impurities, and reduces the viscosity of the molten metallic sulfur slag. After the viscosity reduction is completed, the slag to be separated is pressurized and hot-filtered. After cooling the filtrate or granulation, a high-purity sulfur product can be obtained. Therefore, the present invention can effectively reduce the viscosity of metal sulfur slag during melting and filtration, achieve efficient separation and recovery of metal impurities such as metal sulfides from sulfur, and reduce the stockpiling of metal sulfur slag.

[0062] The technical solutions provided by the present invention will be described in detail below with reference to specific examples, but they should not be construed as limiting the scope of protection of the present invention.

[0063] Example 1

[0064] A method for enhancing the filtration and separation of sulfur from metallic sulfur slag includes the following steps:

[0065] 1. Using polymetallic sulfur slag (No. 1 polymetallic sulfur slag) as raw material, its main components are: S 83wt%, Zn 4wt%, Fe 3wt%, Pb 0.36wt%, and others 9.64wt%; its XRD corresponding... Figure 2 As can be seen from the #1 polymetallic sulfur slag (original sample) in this embodiment, S8, ZnS, FeS2 and PbSO4 phases are present in the polymetallic sulfur slag.

[0066] Dilute sulfuric acid was added to the polymetallic sulfur slag at a liquid-to-solid ratio of 5L:1kg to adjust the pH to 3. The temperature was then raised to 50℃ and stirred for 30 minutes. The temperature was then lowered to 35℃, stirred at 500 rpm, and aerated with forced air for 1 hour. A 1wt% impurity-removing and regulating reagent was then added, and the stirring speed was increased to 200 rpm. The temperature was maintained at 30℃ for 4 hours to remove most of the soluble metal sulfates and other substances. The mixture was then pumped into an equalization tank. The polymetallic sulfur slag was repeatedly washed with water in the equalization tank until the pH of the washing liquid was neutral. The underflow was then pumped to a belt filter for vacuum filtration to achieve a water content of 10% in the filter residue (polymetallic sulfur slag).

[0067] Add control reagents by mass fraction. Specifically, the composition of the impurity removal control reagents is: 60% ferric sulfate, 15% sodium chloride, and 25% ammonium chloride.

[0068] The dehydrated filter residue (polymetallic sulfur slag) is directly fed into the coarse sulfur hydrocyclone via a belt conveyor. The temperature in the hydrocyclone is 152℃. Molten sulfur is continuously pumped into the hydrocyclone to melt the newly fed dehydrated filter residue. After holding at this temperature for 60 minutes, the molten sulfur (molten polymetallic sulfur slag) is discharged from the bottom of the coarse sulfur hydrocyclone into a coarse sulfur pool with stirring.

[0069] 2. Molten sulfur (molten polymetallic sulfur slag) was directly fed into a coarse sulfur tank with stirring, and its viscosity was measured to be 2283 mPa·s.

[0070] After holding the mixture at a stirring speed of 200 rpm and a temperature of 150 °C for 20 min, a sulfur viscosity control agent (viscosity regulator) at a concentration of 0.015 mol / kg was added to the molten sulfur (molten polymetallic sulfur slag). Then, the mixture was held at a stirring speed of 160 rpm and a temperature of 150 °C for 30 min to obtain the molten sulfur slag (molten slag to be separated) after viscosity reduction control. Its viscosity was measured to be 885 mPa·s.

[0071] The viscosity control reagent is added by mass fraction. Specifically, the composition of the sulfur viscosity control reagent is: 65% 2-amino-4-methylbenzothiazole, 16% dibenzothiazole disulfide, 10% 2-aminobenzothiazole, 2% tetramethylthiuram disulfide, 5% diphenylguanidine, and 2% N,N-dimethyl-2-benzothiazole sulfenamide.

[0072] 3. The molten sulfur slag (molten slag to be separated) after viscosity reduction and adjustment is pumped into a hot filter (150℃ temperature) for filtration (pressure 0.6MPa, filter diameter 0.10μm) to obtain metal filter residue and high-purity sulfur liquid; the high-purity sulfur liquid is granulated and packaged to obtain sulfur products.

[0073] In this embodiment, the XRD correspondence of the sulfur product is... Figure 2 The sulfur obtained after processing by Zhongben Technology has a purity of 99.73% in the sulfur product, a sulfur separation and recovery rate of 77.3% in the polymetallic sulfur slag, and heavy metals in the metal filter residue can be further recovered.

[0074] Comparative Example 1

[0075] Compared to Example 1, this comparative example did not add a sulfur viscosity control agent to the molten sulfur (molten polymetallic sulfur slag).

[0076] Specifically:

[0077] 1. Molten sulfur (molten polymetallic sulfur slag) was directly fed into a coarse sulfur tank with stirring, and its viscosity was measured to be 2278 mPa·s.

[0078] After holding at a stirring rate of 200 rpm and a temperature of 150°C for 20 min, the mixture was then held at a stirring rate of 160 rpm and a temperature of 150°C for 30 min.

[0079] 2. The molten sulfur (molten polymetallic sulfur slag) of the same type as in Example 1 is pumped into a hot filter (temperature 150°C) for filtration (pressure 0.6MPa, filter diameter 0.1μm) to obtain metal filter residue and high-purity sulfur liquid; the high-purity sulfur liquid is granulated and packaged to obtain sulfur product.

[0080] In this comparative example, the purity of sulfur in the sulfur product was 99.05%, and the sulfur separation and recovery rate in the polymetallic sulfur slag was 52%.

[0081] Comparative Example 2

[0082] Compared to Example 1, this comparative example did not add any impurity removal and control reagents to the molten sulfur (molten polymetallic sulfur slag).

[0083] Specifically:

[0084] 1. Using polymetallic sulfur slag (No. 1 polymetallic sulfur slag) as raw material, dilute sulfuric acid was added to the polymetallic sulfur slag at a liquid-to-solid ratio of 5L:1kg to adjust the pH to 3. The temperature was then raised to 50℃ and stirred for 30 minutes. The temperature was then lowered to 35℃, and the mixture was stirred at 500rpm with aeration for 1 hour. After removing most of the soluble metal sulfates and other substances, the mixture was pumped into an equalization tank. In the equalization tank, the polymetallic sulfur slag was washed multiple times with water until the pH of the washing liquid was neutral. The underflow was then pumped to a belt filter for vacuum filtration, resulting in a water content of 10% in the filter residue (polymetallic sulfur slag).

[0085] The dehydrated filter residue (polymetallic sulfur slag) is directly fed into the coarse sulfur hydrocyclone via a belt conveyor. The temperature in the hydrocyclone is 152℃. Molten sulfur is continuously pumped into the hydrocyclone to melt the newly fed dehydrated filter residue. After holding at this temperature for 60 minutes, the molten sulfur (molten polymetallic sulfur slag) is discharged from the bottom of the coarse sulfur hydrocyclone into a coarse sulfur pool with stirring.

[0086] 2. Molten sulfur (molten polymetallic sulfur slag) was directly fed into a coarse sulfur tank with stirring, and its viscosity was measured to be 2633 mPa·s.

[0087] After holding the mixture at a stirring speed of 200 rpm and a temperature of 150 °C for 20 min, a sulfur viscosity control agent (viscosity regulator) at a concentration of 0.015 mol / kg was added to the molten sulfur (molten polymetallic sulfur slag). Then, the mixture was held at a stirring speed of 160 rpm and a temperature of 150 °C for 30 min to obtain the molten sulfur slag (molten slag to be separated) after viscosity reduction control. Its viscosity was measured to be 944 mPa·s.

[0088] The viscosity control reagent is added by mass fraction. Specifically, the composition of the sulfur viscosity control reagent is: 65% 2-amino-4-methylbenzothiazole, 16% dibenzothiazole disulfide, 10% 2-aminobenzothiazole, 2% tetramethylthiuram disulfide, 5% diphenylguanidine, and 2% N,N-dimethyl-2-benzothiazole sulfenamide.

[0089] 3. The molten sulfur (molten polymetallic sulfur slag) of the same type as in Example 1 is pumped into a hot filter (temperature 150°C) for filtration (pressure 0.6MPa, filter diameter 0.1μm) to obtain metal filter residue and high-purity sulfur liquid; the high-purity sulfur liquid is granulated and packaged to obtain sulfur product.

[0090] In this comparative example, the purity of sulfur in the sulfur product was 99.05%, and the sulfur separation and recovery rate in the polymetallic sulfur slag was 69%.

[0091] Comparative Example 3

[0092] Compared to Example 1, this comparative example omits 2-mercaptobenzothiazole, dibenzothiazole disulfide, and 2-aminobenzothiazole from the sulfur viscosity control reagents.

[0093] Specifically:

[0094] 1. Molten sulfur (molten polymetallic sulfur slag) was directly fed into a coarse sulfur tank with stirring, and its viscosity was measured to be 2293 mPa·s.

[0095] After holding the mixture at a stirring speed of 200 rpm and a temperature of 150 °C for 20 min, a sulfur viscosity control agent (viscosity regulator) at a concentration of 0.015 mol / kg was added to the molten sulfur (molten polymetallic sulfur slag). Then, the mixture was held at a stirring speed of 160 rpm and a temperature of 150 °C for 30 min to obtain the molten sulfur slag (molten slag to be separated) after viscosity reduction control. Its viscosity was measured to be 1385 mPa·s.

[0096] The sulfur viscosity modifier, by mass fraction, consists of: 65% tetramethylthiuram disulfide, 25% diphenylguanidine, and 10% N,N-dimethyl-2-benzothiazolyl sulfenamide.

[0097] 3. The molten sulfur slag (molten slag to be separated) after viscosity reduction and adjustment is pumped into a hot filter (150℃ temperature) for filtration (pressure 0.6MPa, filter diameter 0.1μm) to obtain metal filter residue and high-purity sulfur liquid; the high-purity sulfur liquid is granulated and packaged to obtain sulfur products.

[0098] The same molten sulfur (molten polymetallic sulfur slag) as in Example 1.

[0099] In this comparative example, the sulfur purity in the sulfur product was 99.12%, and the sulfur separation and recovery rate in the polymetallic sulfur slag was 61%. Meanwhile, ... Figure 3 As shown, adding too much thiuram caused the sulfur-separated product to turn brownish-black.

[0100] Example 2

[0101] Compared to Example 1, this embodiment omits tetramethylthiuram disulfide from the sulfur viscosity regulating reagent.

[0102] Specifically:

[0103] 1. The molten sulfur (molten polymetallic sulfur slag) of the same type as in Example 1 was directly introduced into a coarse sulfur tank with stirring, and its viscosity was measured to be 2295 mPa·s.

[0104] After holding the mixture at a stirring speed of 200 rpm and a temperature of 150 °C for 20 min, a sulfur viscosity control agent (viscosity regulator) at a concentration of 0.015 mol / kg was added to the molten sulfur (molten polymetallic sulfur slag). Then, the mixture was held at a stirring speed of 160 rpm and a temperature of 150 °C for 30 min to obtain the molten sulfur slag (molten slag to be separated) after viscosity reduction control. Its viscosity was measured to be 1198 mPa·s.

[0105] The sulfur viscosity control reagent, by mass fraction, consists of: 65% 2-mercaptobenzothiazole, 16% dibenzothiazole disulfide, 10% 2-aminobenzothiazole, 7% diphenylguanidine, and 2% N,N-dimethyl-2-benzothiazole sulfenamide.

[0106] 2. The molten sulfur slag (molten slag to be separated) after viscosity reduction and adjustment is pumped into a hot filter (150℃ temperature) for filtration (pressure 0.6MPa, filter diameter 0.1μm) to obtain metal filter residue and high-purity sulfur liquid; the high-purity sulfur liquid is granulated and packaged to obtain sulfur products.

[0107] In this comparative example, the sulfur purity in the sulfur product was 99.22%, and the sulfur separation and recovery rate in the polymetallic sulfur slag was 68%. This indicates that introducing a small amount of tetramethylthiuram disulfide can significantly improve the sulfur separation and recovery efficiency.

[0108] Comparative Example 4

[0109] Compared to Example 1, this comparative example omits diphenylguanidine and N,N-dimethyl-2-benzothiazolyl sulfenamide from the sulfur viscosity regulating reagent.

[0110] Specifically:

[0111] 1. The molten sulfur (molten polymetallic sulfur slag) of the same type as in Example 1 was directly introduced into a coarse sulfur tank with stirring, and its viscosity was measured to be 2274 mPa·s.

[0112] After holding the mixture at a stirring speed of 200 rpm and a temperature of 150 °C for 20 min, a sulfur viscosity control agent at a concentration of 0.015 mol / kg was added to the molten sulfur (molten polymetallic sulfur slag). Then, the mixture was held at a stirring speed of 160 rpm and a temperature of 150 °C for 30 min to obtain the molten sulfur slag (molten slag to be separated) after viscosity reduction control. Its viscosity was measured to be 1266 mPa·s.

[0113] The sulfur viscosity control reagent, by mass fraction, consists of: 65% 2-mercaptobenzothiazole, 16% dibenzothiazole disulfide, 17% 2-aminobenzothiazole, and 2% tetramethylthiuram disulfide.

[0114] 2. The molten sulfur slag (molten slag to be separated) after viscosity reduction and adjustment is pumped into a hot filter (150℃ temperature) for filtration (pressure 0.6MPa, filter diameter 0.1μm) to obtain metal filter residue and high-purity sulfur liquid; the high-purity sulfur liquid is granulated and packaged to obtain sulfur products.

[0115] In this comparative example, the purity of sulfur in the sulfur product was 99.33%, and the sulfur separation and recovery rate in the polymetallic sulfur slag was 65%.

[0116] Example 3

[0117] A method for enhancing the filtration and separation of sulfur from metallic sulfur slag includes the following steps:

[0118] Using polymetallic sulfur slag (No. 2 polymetallic sulfur slag) as raw material, its main components are: S 74wt%, Zn 5wt%, Fe 11wt%, Pb 1.44wt%, and others 8.56wt%.

[0119] Dilute sulfuric acid was added to the polymetallic sulfur slag at a liquid-to-solid ratio of 5 L:1 kg to adjust the pH to 2. The temperature was then raised to 55°C and stirred for 30 minutes. The temperature was then lowered to 25°C, and the mixture was stirred at 350 rpm with aeration for 1 hour. A 1 wt% impurity removal and conditioning reagent was then added, and the mixture was stirred at 200 rpm at 25°C for 10 hours to remove most of the soluble metal sulfates and other substances. The mixture was then pumped into an equalization tank. The polymetallic sulfur slag was repeatedly washed with water in the equalization tank until the pH of the washing liquid was neutral. The underflow was then pumped to a belt filter for vacuum filtration, reducing the water content of the filter residue (polymetallic sulfur slag) to 11%.

[0120] Add control reagents by mass fraction. Specifically, the composition of the impurity removal control reagents is: 30% ferric sulfate, 10% sodium chloride, and 60% ammonium chloride.

[0121] The dehydrated filter residue (polymetallic sulfur slag) is directly fed into the coarse sulfur hydrocyclone via a belt conveyor. The temperature in the hydrocyclone is 155℃. Molten sulfur is continuously pumped into the hydrocyclone to melt the newly fed dehydrated filter residue. After holding at this temperature for 60 minutes, the molten sulfur (molten polymetallic sulfur slag) is discharged from the bottom of the coarse sulfur hydrocyclone into a coarse sulfur pool with stirring.

[0122] 2. Molten sulfur (molten polymetallic sulfur slag) was directly fed into a coarse sulfur tank with stirring, and its viscosity was measured to be 2483 mPa·s.

[0123] After holding the mixture at a stirring speed of 200 rpm and a temperature of 150 °C for 30 min, a sulfur viscosity control agent at a concentration of 0.010 mol / kg was added to the molten sulfur (molten polymetallic sulfur slag). Then, the mixture was held at a stirring speed of 200 rpm and a temperature of 150 °C for 45 min to obtain the molten sulfur slag (molten slag to be separated) after viscosity reduction control. Its viscosity was measured to be 1045 mPa·s.

[0124] By mass fraction, the regulating agent is added. Specifically, the composition of the sulfur viscosity regulating agent is: 48% 2-mercaptobenzothiazole, 50% dibenzothiazole disulfide, and 2% diphenylguanidine.

[0125] 3. Pump the molten sulfur slag (molten slag to be separated) after viscosity reduction and adjustment into a hot filter (150℃) for filtration (pressure 0.6MPa, filter diameter 0.1μm) to obtain metal filter residue and high-purity sulfur liquid; granulate and package the high-purity sulfur liquid to obtain sulfur products.

[0126] In this embodiment, the sulfur purity in the sulfur product is 99.68%, the sulfur separation and recovery rate in the polymetallic sulfur slag is 73%, and the heavy metals in the metal filter residue can be further recovered.

[0127] Example 4

[0128] A method for enhancing the filtration and separation of sulfur from metallic sulfur slag includes the following steps:

[0129] 1. Using polymetallic sulfur slag (No. 3 polymetallic sulfur slag) as raw material, its main components are: S 78.6wt%, Zn 8.6wt%, Fe 9.1wt%, Pb 1.4wt%, and others 2.3wt%.

[0130] Dilute sulfuric acid was added to the polymetallic sulfur slag at a liquid-to-solid ratio of 5L:1kg to adjust the pH to 1. The temperature was then raised to 65℃ and stirred for 45 minutes. The temperature was then lowered to 25℃, stirred at 400 rpm, and aerated with forced air for 1 hour. Next, 0.5 wt% of a purification and conditioning reagent was added, and the stirring speed was 200 rpm, the temperature was 28℃, and the time was 5 hours. After removing most of the soluble metal sulfates and other substances, the mixture was pumped into an equalization tank. The polymetallic sulfur slag was then repeatedly washed with water in the equalization tank until the pH of the washing liquid was neutral. The underflow was then pumped to a belt filter for vacuum filtration, reducing the water content of the filter residue (polymetallic sulfur slag) to 8%.

[0131] Add control reagents by mass fraction. Specifically, the composition of the impurity removal control reagents is: 30% ferric sulfate, 15% sodium chloride, and 55% ammonium chloride.

[0132] The dehydrated filter residue (polymetallic sulfur slag) is directly fed into the coarse sulfur hydrocyclone via a belt conveyor. The temperature in the hydrocyclone is 155℃. Molten sulfur is continuously pumped into the hydrocyclone to melt the newly fed dehydrated filter residue. After holding at this temperature for 80 minutes, the molten sulfur (molten polymetallic sulfur slag) is discharged from the bottom of the coarse sulfur hydrocyclone into a coarse sulfur pool with stirring.

[0133] 2. Molten sulfur (molten polymetallic sulfur slag) was directly fed into a coarse sulfur tank with stirring, and its viscosity was measured to be 2764 mPa·s.

[0134] After holding the mixture at a stirring speed of 200 rpm and a temperature of 150 °C for 30 min, a sulfur viscosity control agent at a concentration of 0.025 mol / kg was added to the molten sulfur (molten polymetallic sulfur slag). Then, the mixture was held at a stirring speed of 250 rpm and a temperature of 150 °C for 60 min to obtain the molten sulfur slag (molten slag to be separated) after viscosity reduction control. Its viscosity was measured to be 1066 mPa·s.

[0135] The viscosity control reagent is added by mass fraction. Specifically, the composition of the sulfur viscosity control reagent is: 15% 2-amino-4-methylbenzothiazole, 79% dibenzothiazole disulfide, 2% tetramethylthiuram disulfide, and 4% diphenylguanidine.

[0136] 3. The molten sulfur slag (molten slag to be separated) after viscosity reduction and adjustment is pumped into a hot filter (150℃) in batches for filtration (pressure 0.6MPa, filter diameter 0.45μm) to obtain metal filter residue and high-purity sulfur liquid; the high-purity sulfur liquid is granulated and packaged to obtain sulfur products.

[0137] In this embodiment, the sulfur purity in the sulfur product is 99.30%, the sulfur separation and recovery rate in the polymetallic sulfur slag is 72%, and the heavy metals in the metal filter residue can be further recovered.

[0138] 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 enhancing the filtration and separation of sulfur from metallic sulfur slag, characterized in that: The metallic sulfur slag was slurried with acid, and the resulting slurry was subjected to aeration, impurity removal, water washing, dehydration, drying and melting treatment in sequence. After adding a viscosity modifier to the molten metallic sulfur slag and stirring the reaction, it was separated by pressure filtration to obtain sulfur liquid. The impurity removal process employs impurity removal regulators including ferric sulfate, sodium chloride, and ammonium chloride. The viscosity modifier contains thiazoles and guanidines.

2. The method for enhanced sulfur filtration and separation from metallic sulfur slag 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%. The amount of the impurity removal and control reagent used is 0.5 to 3 wt% of the mass of the metal sulfur slag.

3. The method for enhanced sulfur filtration and separation from metallic sulfur slag according to claim 1, characterized in that: The viscosity modifier comprises the following components by mass percentage: 90-98% thiazoles and 2-10% guanidines.

4. A method for enhanced sulfur filtration and separation from metallic sulfur slag according to claim 1 or 3, characterized in that: The thiazole substance is at least one of 2-mercaptobenzothiazole, 2-amino-4-methylbenzothiazole, 2-aminobenzothiazole, and dibenzothiazole disulfide; The guanidine substance is diphenylguanidine.

5. A method for enhanced sulfur filtration and separation from metallic sulfur slag according to claim 1 or 3, characterized in that: The viscosity modifier includes thiuram derivatives and / or sulfenamide derivatives; the mass fraction of thiuram derivatives and sulfenamide derivatives in the viscosity modifier does not exceed 5%; The thiuram-like substance is tetramethylthiuram disulfide and / or tetramethylthiuram monosulfide; The sulfonamide is N,N-dimethyl-2-benzothiazolyl sulfonamide.

6. A method for enhanced sulfur filtration and separation from metallic sulfur slag according to claim 1 or 3, characterized in that: The amount of the viscosity modifier is 0.05 to 0.30 mol / kg of the mass of the metal sulfur slag.

7. The method for enhanced sulfur filtration and separation from metallic sulfur slag according to claim 1, characterized in that: The conditions for the stirring reaction are: stirring at 140–150°C for 20–60 min.

8. A method for enhanced sulfur filtration and separation from metallic sulfur slag according to claim 1, 2, 3 or 7, characterized in that: The main components and their mass content in the metal sulfur slag are: S > 55%, Fe < 20%, Zn < 10%, Pb < 3%.

9. A method for enhanced sulfur filtration and separation from metallic sulfur slag according to claim 1, 2, 3 or 7, characterized in that: The conditions for preparing the slurry are: temperature of 45–100℃ and pH of acid solution of 1–4. The conditions for impurity removal are: stirring speed 150-350 rpm, temperature 25-45℃, and time 4-16 h. The moisture content of the dehydrated metallic sulfur slag is <12wt%. The melting conditions are: temperature of 150-155℃ and holding time of 30-200min.

10. A method for enhanced sulfur filtration and separation from metallic sulfur slag according to claim 1, 2, 3 or 7, characterized in that: The pressure applied during the filter press process is 0.6 to 0.8 MPa.

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