Comprehensive treatment method of fused salt chlorination slag

Abstract

The invention discloses a comprehensive treatment method of fused salt chlorination slag, and relates to the technical field of recycling of fused salt chlorination slag. Comprising the following steps: S1, ball-milling and pulping; s2, primary filtering; s3, alkali adding and size mixing; s4, carrying out secondary filtration; s5, adding acid for neutralization; and S6, removing impurities. By adding ball milling, washing and filtering means to the fused salt chlorination slag, most of NaCl in the waste fused salt, namely the fused salt chlorination slag, can be dissolved, the influence of sodium chloride hardening during roasting is reduced, and meanwhile the dechlorination effect of metal chloride is good; and part of valuable metal recovery products are removed in advance, so that the difficulty of subsequent enrichment and recovery of NaCl is further reduced, and valuable metal resources in the fused salt chlorination slag are recycled as much as possible. NaCl in the molten salt chlorination slag is refined into saline water for a chlor-alkali process, so that the step of evaporating and concentrating the saline water into industrial salt is reduced, the energy consumption is reduced, and coupling of the titanium dioxide-chlor-alkali industry is realized.

Description

Technical Field

[0001] The invention relates to the technical field of recycling titanium metallurgical solid waste, and in particular to the technical field of recycling molten salt chlorinated slag. Background Art

[0002] my country has rich reserves of titanium resources. At present, the total proven reserves of titanium dioxide have reached more than 900 million tons, ranking first in the world. Among them, the reserves in Panzhihua, Sichuan are the largest, and its titanium resources account for more than 90% of the national titanium reserves. It is mainly composed of rock-type ilmenite, with complex ore composition, many associated minerals, low grade, and high calcium and magnesium impurity content. There are two main processes for producing titanium tetrachloride in my country: boiling chlorination method and molten salt chlorination method. Among them, the molten salt chlorination method will produce a large amount of molten salt chloride slag in the process of producing TiCl4. According to statistics, for every 10kt of commercial sponge titanium produced, about 11.7kt of molten salt chloride slag will be produced in the process of molten salt chlorination production. The slag contains a variety of chloride salts, including: NaCl, MgCl2, MnCl2, CaCl2, FeCl3, FeCl2 and AlCl3, etc. In addition, it is also enriched with a variety of metal impurities and oxides brought in by titanium-rich materials and petroleum coke, such as: TiO2, SiO2 and C single substance, etc.

[0003] The chemical composition of molten salt chloride slag is complex. Because it contains a large amount of Cl elements, it is difficult to achieve harmless treatment. The current treatment methods can be divided into stacking and deep burial treatment, water-soluble method and non-water-soluble method. The most commonly used treatment method is direct stacking or landfilling, which will cause the soluble chloride salts in the slag to enter the groundwater and soil, causing environmental problems such as groundwater pollution and soil salinization; and volatile chlorine and other toxic gases may appear in the slag, which are easily dissipated under the influence of temperature, sunlight and wind, and enter the atmosphere to cause pollution; in addition, the slag is also enriched with various metals brought in from minerals. If not handled in time, it will also cause serious damage to the environment. Among them, the water-soluble method can only recover certain substances in the molten salt chloride slag in a targeted manner, and the process is complicated, the amount of wastewater generated is large, and the impurity treatment is difficult. A large amount of waste salt has not been effectively recycled and utilized, and it is difficult to apply it in industry. At the same time, most of the residues after filtration still need to be stacked for treatment, which is easy to cause secondary pollution and cannot effectively solve the problem of valuable component recovery and safe disposal of molten salt chloride slag.

[0004] Chinese patent application number CN201410014683.6 discloses a comprehensive treatment method for waste molten salt and dust slag produced by chlorination of titanium tetrachloride molten salt: first, the waste molten salt discharged from the molten salt chlorination furnace is crushed and the crushed slag is ground; the dust slag is pulped and dispersed to prepare a solid-liquid mixture; the waste molten salt powder and the solid-liquid mixture of dust slag are mixed to prepare a mixture; the mixture is oxidized and roasted under the condition of passing air and water vapor, and the generated hydrogen chloride and chlorine pass through a leaching system to generate hydrochloric acid, and the generated waste gas meets the emission standards; the agglomerated slag after roasting is crushed and screened, and subjected to alkali solution neutralization treatment, and the part of the chloride that has not been completely removed reacts with the alkali solution to generate corresponding hydroxides and brine. In the invention, a high-temperature oxidation roasting method is used to make most of the chlorides in the slag react with oxygen to generate corresponding oxides, chlorine and hydrogen chloride gas. These gases are passed through a leaching system to produce hydrochloric acid to recycle this part of the chloride ions. Through alkaline leaching, the chlorides remaining in the roasted slag react with alkali solution to be converted into hydroxide sediments. The treated slag obtained by washing can be widely used as building materials. Although the application reduces the environmental hazards caused by waste molten salt and dust collecting slag on the one hand, it also recovers the chloride ions and some valuable elements in the waste molten salt and dust collecting slag on the other hand, and obtains treated slag with a wide range of uses. However, for waste molten salt, its composition is mainly NaCl (content>30wt%). If it is roasted without treatment, a large amount of NaCl will be plated and wrapped with MgCl2 (content>15wt%), FeCl2 (content>15wt%), etc., and the dechlorination effect is poor and very energy-consuming. In addition, the treated slag finally obtained by the application still contains a large amount of water, and usually needs to be roasted again before it can be used, which further increases energy consumption.

[0005] The Chinese patent application number CN202311355985.5 discloses a method for removing impurities from crude brine based on molten salt chlorination slag, the method comprising: S1, adding lime milk to molten salt chlorination slag to obtain saturated crude brine with a pH of 5.8 to 6.2, and after the saturated crude brine is fully mixed and reacted, qualified crude brine is obtained; S2, adding waste alkali solution to the qualified crude brine, wherein the amount of waste alkali solution added is 0.18 to 0.24 according to the molar ratio of effective chlorine to ferrous ion, and after the addition is completed and the reaction is allowed to stand, the reaction is carried out. Filter treatment to obtain mixed brine and iron-containing sludge; S3, add decalcifying agent to the mixed brine under stirring, adjust pH to 8.0-8.5, then stand and filter to separate, obtain demagnesized brine and Ca-containing slag; S4, heat the demagnesized brine to 90-95°C, add sodium carbonate solution, and after sufficient reaction, stand and filter to separate, obtain purified qualified brine and basic magnesium carbonate; step S5, configure qualified brine and hydrochloric acid in a volume ratio of 1:1 to form qualified NaCl brine with a pH of 4.6-4.9. Although the invention mentions how to make crude brine from molten salt chlorination slag, it does not mention the refined use of crude brine, and the application uses a large number of impurity removal agents in the impurity removal process. For the recovery of other valuable metals mentioned in its specification, additional processing steps are often required, resulting in cumbersome procedures and reduced recovery efficiency.

[0006] The Chinese patent application number CN202410468083.0 discloses a method for treating molten salt chlorination slag and tail gas. The method comprises the following steps: crushing the molten salt chlorination slag and dissolving it, stirring and keeping warm during the dissolution process, filtering after it is completely dissolved to obtain a filtrate; neutralizing the filtrate with a sodium hydroxide solution, stirring slowly during the neutralization process, and heating during the neutralization process; filtering after the neutralization is completed to obtain a crude brine; introducing the tail gas of the chlorination furnace process after multi-stage washing treatment into the crude brine to adjust the pH, and at the same time making the calcium ions Ca 2+ Further precipitation; after adjusting the pH, the crude salt water solution is subjected to filter pressing to obtain refined brine; the refined brine is evaporated and crystallized to obtain industrial salt, which is then reused in the chlorination furnace for production. The design of this invention can effectively remove calcium from the molten salt chlorination slag solution, and can optimize the process of preparing industrial salt after the chlorination waste slag is dissolved in water, while reducing CO2 emissions. However, this application uses a filter pressing separation method, and does not control the slurry or solution obtained in the intermediate process. The energy consumption during evaporation and crystallization of the refined brine is high, and improper temperature control can easily cause the industrial salt to form agglomerates. At the same time, other solid slag materials are still piled up, which can easily cause environmental pollution, and the recovery of valuable metals is not thorough.

[0007] In summary, due to the complex element composition in molten salt chloride slag, especially the high content of NaCl, the prior art provides more guidance for the recovery of NaCl, but the means of roasting often cause the problem of NaCl agglomeration and wrapping other chlorides, and if more types of impurity removal agents are used to remove impurities and purify NaCl, in addition to causing cumbersome process and increased cost, it will also increase the difficulty of handling subsequent mixed solutions. And the above processing ideas cannot fully recover the valuable metals in molten salt chloride slag, causing waste of resources, and the situation of stacking materials polluting the environment may occur. Therefore, how to overcome the cumbersome recovery process and high energy consumption caused by the complex components, and the inability to efficiently realize the comprehensive utilization of valuable metals in molten salt chloride slag has become a technical problem to be solved by technicians in this field. Summary of the invention

[0008] In view of the current resource treatment methods of molten salt chloride slag, it is often necessary to recover NaCl therein, which results in the inability to effectively utilize the remaining valuable metals or the complicated enrichment process. The purpose of the present invention is to provide a comprehensive treatment method for molten salt chloride slag, by adding operations such as ball milling and filtration, and setting process parameters of related processes, it is possible to first recover part of the valuable metals while reducing the influence of NaCl on the process, and ultimately the valuable metals in the molten salt chloride slag can be fully and efficiently reused.

[0009] The technical solution adopted by the present invention to solve its technical problem is:

[0010] A comprehensive treatment method for molten salt chlorinated slag comprises the following steps:

[0011] S1: ball milling: collect the molten salt chlorination slag, add water, and disperse it in a wet ball mill for 10 to 20 minutes, wherein the ore-to-slurry ratio is set to 1:3 to 1:4, and the ball loading amount of the wet ball mill is 25 to 30%, to obtain chlorination slag slurry.

[0012] S2: primary filtration: the chlorinated residue slurry is filtered for the first time in a vacuum belt filter at a negative pressure of 0.2-0.4 MPa. The filter screen is 1-5 μm in size. During the filtration process, the slurry is washed with industrial water for 2-3 times. The amount of industrial water used is 1-2 times of the chlorinated residue slurry. A first filter residue and a first filtrate are obtained. The water content of the first filter residue is 15-20 wt%. The first filter residue is placed in a tunnel kiln or a rotary kiln. After being calcined at 300-500° C. for 4-5 hours, the filter residue is used for building materials. The solid content of the first filtrate is <1 wt%, and the NaCl content is >30 g / L.

[0013] S3: adding alkali to adjust the slurry: adjusting the pH value of the first filtrate to 8-10 with alkali solution to obtain a first neutralized solution.

[0014] S4: Secondary filtration: The first neutralized liquid is filtered for the second time in a vacuum belt filter at a negative pressure of 0.2-0.4 MPa. The filter screen is 1-5 μm in size. During the filtering process, the filter is washed with industrial water for 2-3 times. The amount of industrial water used is 0.5-1 times of the first neutralized liquid. A second filter residue and a second filtrate are obtained. The water content of the second filter residue is 20-30 wt%. The second filter residue is placed in a tunnel kiln or a rotary kiln. After being calcined at 300-500°C for 4-5 hours, it is used for building materials. The NaCl content in the second filtrate is >15 g / L.

[0015] S5: Acid neutralization: The pH value of the second filtrate is adjusted to 7-8 with acid to obtain a second neutralized solution, wherein the NaCl content is greater than 15 g / L;

[0016] S6: Impurity removal: The second neutralized liquid is sequentially filtered and filtered through a resin tower for impurity removal, and then concentrated through a membrane concentration device to obtain concentrated brine. The NaCl content in the concentrated brine is 20-50 g / L. The concentrated brine is used in the chlor-alkali electrolysis process after adjusting the concentration with industrial salt.

[0017] The process of producing titanium tetrachloride by molten salt chlorination method often produces a large amount of molten salt chlorination slag waste, in which the Cl element rich needs to be harmlessly treated, and NaCl is usually the main component (content>30wt%). Therefore, in the prior art, the recovery and purification of this part of sodium chloride is also the main task of resource utilization. However, due to the complex composition of the waste molten salt, the soluble metal ions are relatively large, and the NaCl crystals are very easy to agglomerate and wrap other metal chlorides during the roasting process. Whether it is dissolving and pulping and adding reagents to extract the NaCl component, or roasting and oxidizing to remove other metal components, the valuable metal ions in the waste molten salt will eventually be not completely recovered, or further cause the process to be lengthy and the processing cost to increase.

[0018] In this application, the molten salt chloride slag is first slurried and ball-milled in a wet ball mill. Working in a wet environment, the material is more easily captured by the grinding medium and evenly dispersed, so that the minerals with soluble metal ions as the main components are more fully dissociated, and the mutual friction and collision of the balls promote more NaCl to dissolve in water. Then the obtained chloride slag slurry is filtered with a vacuum belt filter, the negative pressure is set to 0.2-0.4MPa, and the filter screen adopts a specification of 1-5μm. During the filtering process, it is washed with industrial water 2-3 times, which can further make the NaCl with better solubility + , Cl -Dissolved in the filtrate, and reduce the chloride ion content in the solid slag after filtration, and there will be no NaCl agglomeration and wrapping of other chlorides in the slag for roasting, resulting in a decrease in recovery efficiency. At the same time, the above filtration conditions are used to design two filtrations, and the number of washings can be controlled to allow other insoluble or slightly soluble alkali metal minerals, colloids, etc. to be better filtered out. A large amount of valuable metals in the molten salt chloride slag are recovered after roasting, and can be directly sent to cement plants for supplementing metal elements in building materials. The key is that the partially recyclable valuable metals are removed from the molten salt chloride slag after roasting, which can reduce the influence of the remaining soluble metal impurity ions on NaCl, reduce the difficulty of impurity removal and enrichment of NaCl in subsequent steps, and finally make the valuable metals in the molten salt chloride slag be fully recycled, and only one roasting is required to achieve the above effect, with low energy consumption and high efficiency.

[0019] Specifically, the processing method of the present application includes S1: ball milling and slurrying. First, the molten salt chloride slag is collected and water is added, and the pulp ratio is set to 1:3-1:4, so that the mixed material maintains good fluidity and is ball milled and slurried in a wet ball mill, wherein the minerals are dissociated and evenly dispersed, and the ball milling time is controlled to be 10-20 minutes. The grinding and dissociation effect of the solid particles is good, and the chloride slag slurry with suitable particle size is obtained, and the NaCl therein can be fully dissolved, which is beneficial to the subsequent filtration and roasting while improving the recovery efficiency of the brine. Further, the ball loading of the wet ball mill is controlled to be 25-30%, preferably 30%, so that the mixed slurry can be better ground and dissociated. If the ball loading is too low, the grinding effect of the mixed slurry under the above pulp ratio is poor. If the ball loading is too high, the grinding load of the device is high, which causes waste and the relative processing capacity will be reduced. It can be understood that the ball loading here, that is, the filling rate, refers to the volume percentage of the added balls to the total amount of materials in the ball mill.

[0020] After obtaining the chloride residue slurry, the first filtration is carried out to control the water content of the first filter residue to be 15-20wt%, wherein the components are mainly C, SiO2, TiO2 and other insoluble substances and part of FeCl2, FeCl 3、 The colloid formed by AlCl3 and the like has a good filtering effect in a vacuum belt filter with a negative pressure of 0.2-0.4MPa and a filter screen of 1-5μm. The first filter residue obtained can be directly used for building materials after roasting. And industrial water is used for washing 2-3 times while filtering, and the solid content in the first filtrate obtained is controlled to be less than 1wt%, and the NaCl content is controlled to be greater than 30g / L, which is conducive to the subsequent enrichment and recovery of NaCl. Furthermore, the amount of industrial water used for washing in the first filtration in S2 is controlled to be 1-2 times of the above-mentioned chlorinated slag slurry, which can more fully dissolve the NaCl in the slurry on the basis of the fine powder particles obtained by ball milling, so that the subsequent recovery effect is good.

[0021] After some of the valuable metals in the molten salt chloride slag have been roasted and removed, the first filtrate only needs to be neutralized with alkali solution and the pH value is controlled to 8-10, so that the metal element ions such as Al, Mg, and Fe therein can be precipitated in the form of hydroxides to obtain the first neutralized solution. And because the concentration of alkali metal ions is reduced, the particle fineness of the precipitate in the suspension formed after neutralization is appropriate, and the second filtration can be carried out in the same filtration method as the first filtration, that is, filtering in a vacuum belt filter with a negative pressure of 0.2-0.4MPa and a filter screen of 1-5μm.

[0022] Since the second filtration is designed on the basis of the first filtration, it is used to improve the separation and recovery effect of the molten salt chlorination slag. The water content in the second filter residue obtained by the second filtration is controlled to be 20-30wt%, and its main components are hydroxides of elements such as Al, Mg, and Fe. In addition to more fully extracting the valuable metals for roasting, controlling the amount of industrial water used in the second filtration and washing to 0.5-1 times that of the first neutralization solution can further dissolve the NaCl therein, so that the NaCl content in the second filtrate is greater than 15g / L, achieving the re-enrichment of NaCl. It can be understood that based on the Cl in the molten salt chlorination slag after grinding and pulping in the previous step, - The treatment is relatively sufficient. The first filter residue and the second filter residue obtained by the present application can be directly roasted and used as building materials at the corresponding water content, and the recovery efficiency is relatively high.

[0023] Preferably, the roasting of the first filter residue and the second filter residue in S2 and S4 is carried out in a tunnel kiln or a rotary kiln at a temperature of 300 to 500° C. for 4 to 5 hours. Controlling the roasting temperature and roasting time can achieve a better roasting effect. If the temperature is too low, the metal chloride in the filter residue is difficult to dechlorinate and the time is long. If the temperature is too high, it will lead to high energy consumption. It is understandable that the roasting conditions of the first filter residue and the second filter residue are the same, so the two can be collected to a certain amount and then roasted in the same tunnel kiln or rotary kiln to improve the roasting efficiency and reduce energy consumption.

[0024] The second filtrate with a NaCl content of more than 15 g / L is neutralized with acid and the pH value is controlled to be 7-8, so that the excess alkali solution can be removed and the NaCl content in the second neutralized solution can be kept still more than 15 g / L. Preferably, the alkali solution of the two neutralization reagents is NaOH and the acid solution is HCl, so that no new impurity elements can be introduced and NaCl can be recovered better.

[0025] After that, the second neutralized liquid is decontaminated to recover the NaCl therein. At this time, there are still a small amount of suspended matter and impurity ions such as Ca, Mg, Al, and Fe in the brine, which need to be further decontaminated and refined. Among them, firstly, a filter is used to remove suspended matter, large particles of impurities, etc. in the water, and it can play a role in protecting the concentration system; secondly, the soluble metal impurity ions such as Ca, Mg, Al, and Fe are removed by adsorption in a resin tower, and the decontamination effect is better; then, it is concentrated in a membrane concentration device to obtain a standby concentrated brine, so that the NaCl content reaches 20-50g / L, which can be well adjusted for use in the chlor-alkali electrolysis process.

[0026] Preferably, the concentration of the concentrated brine is adjusted with industrial salt to control the NaCl content therein at 300±5g / L. The industrial salt complies with the first-level standard in Table 1 of GB / T 5462-2015, with NaCl>98.5g / 100g. The obtained saturated brine has less impurities and can be well used in the chlor-alkali electrolysis process to achieve the recovery and utilization of NaCl.

[0027] Preferably, the filter uses a 1-3 μm filter element to better remove suspended matter, large particle impurities, etc. in the water, and better protect the reverse osmosis system; the resin tower uses a macroporous weakly acidic cation exchange resin with a particle size of 10-50 mesh, which has a better adsorption effect on impurity ions; the membrane concentration device uses a reverse osmosis membrane with a pore size of 0.8 nm, and the selective interception of the reverse osmosis membrane has a better concentration effect on NaCl. Preferably, the above equipment can achieve more efficient enrichment and recovery of NaCl.

[0028] Compared with the prior art, the technical solution of the present application has at least the following beneficial effects:

[0029] 1. The present invention adds ball milling, washing and filtering means to the molten salt chloride slag, so that most of the NaCl in the waste molten salt, i.e., the molten salt chloride slag, can be dissolved, and the influence of sodium chloride caking during roasting can be reduced. At the same time, the metal chloride dechlorination effect is good, the roasting times are reduced, and the energy consumption is reduced. Moreover, part of the valuable metal recovery product is removed in advance after roasting, which further reduces the difficulty of subsequent enrichment and recovery of NaCl, and realizes the full reuse of valuable metal resources in the molten salt chloride slag.

[0030] 2. The present invention adopts wet grinding with a wet ball mill and filtering with a vacuum filter. The cooperation of the two can fully dissolve the NaCl in the chlorinated slag and separate it from other valuable metals, thereby improving the yield of NaCl.

[0031] 3. The present invention prepares brine from NaCl in molten salt chloride slag by refining, concentrating and blending brine, which can be used in chlor-alkali process, reduces the steps of evaporating and concentrating brine into industrial salt, reduces energy consumption, and the NaOH and HCl after electrolysis can also be reused in the present invention to achieve recycling of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments and comparative examples. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 It is a specific flow chart of the comprehensive treatment method of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0035] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to specific embodiments.

[0036] Example 1

[0037] like Figure 1 As shown, Figure 1 It is a specific flow chart of the comprehensive treatment method of the present invention.

[0038] A comprehensive treatment method for molten salt chlorinated slag comprises the following steps:

[0039] S1: Ball milling: collect the molten salt chloride slag, add water, and disperse it in a wet ball mill for 10 to 20 minutes, wherein the ore-to-slurry ratio is set to 1:3, and the ball loading of the wet ball mill is 25 to 30%, to obtain chloride slag slurry. The composition after testing is shown in the following table.

[0040] Table 1 Composition of chlorinated slag slurry in Example 1

[0041]

[0042]

[0043] S2: primary filtration: the chlorinated residue slurry is filtered for the first time in a vacuum belt filter at a negative pressure of 0.3 MPa. The filter screen is 5 μm in specification. During the filtration process, the slurry is washed twice with industrial water. The amount of industrial water used is 1 times of the chlorinated residue slurry. A first filter residue and a first filtrate are obtained. The water content in the first filter residue is 18 wt %. The first filter residue is placed in a tunnel kiln and calcined at 450° C. for 4 hours before being used for building materials. The solid content in the first filtrate is <1 wt %, and the NaCl content is 38 g / L.

[0044] S3: adding alkali to adjust the slurry: adjusting the pH value of the first filtrate to 9 with alkali solution to obtain a first neutralized solution.

[0045] S4: Secondary filtration: The first neutralized liquid is filtered for the second time in a vacuum belt filter at a negative pressure of 0.3 MPa. The filter screen adopts a 5 μm specification. During the filtration process, the filter is washed twice with industrial water. The amount of industrial water used is 0.5 times that of the first neutralized liquid. A second filter residue and a second filtrate are obtained. The water content in the second filter residue is 28 wt %. The second filter residue is placed in a tunnel kiln or a rotary kiln, and calcined at 450° C. for 4 hours before being used as a building material. The NaCl content in the second filtrate is 18 g / L.

[0046] S5: Acid neutralization: The pH value of the second filtrate is adjusted to 7 with acid to obtain a second neutralized solution, wherein the NaCl content is 18 g / L;

[0047] S6: Impurity removal: The second neutralized liquid is sequentially filtered and filtered through a resin tower for impurity removal, and then concentrated through a membrane concentration device to obtain concentrated brine, wherein the filter uses a 3μm filter element, the resin tower uses a macroporous weakly acidic cation exchange resin with a particle size of 50 mesh, and the membrane concentration device uses a reverse osmosis membrane with a pore size of 0.8nm. The NaCl content in the concentrated brine is 45g / L. The concentrated brine is used in the chlor-alkali electrolysis process after adjusting the concentration with industrial salt.

[0048] Embodiment 2, 3

[0049] The implementation methods of Examples 2 and 3 are basically the same as those of Example 1, except that some conditions in the specific process steps are adjusted, and the contents of the filtrate and concentrated brine obtained in the three examples are tested. The specific implementation conditions and test results are shown in Tables 2 and 3.

[0050] Table 2 Summary of specific implementation in the embodiments

[0051]

[0052] Table 3 Test results of concentrated brine

[0053] Detection indicators unit Example 1 Example 2 Example 3 Sodium chloride g / L 45 40 43 calcium mg / L 0.008 0.010 0.011 magnesium mg / L 0.0009 0.0012 0.0011 <![CDATA[SiO2]]> mg / L 0.012 0.014 0.016 Al mg / L ND ND ND Fe mg / L 0.023 0.025 0.020 TOC mg / L 7.8 5.6 4.8

[0054] It can be seen from the examples that the technical solution of the present application can effectively remove impurities and enrich and recover the NaCl component in the molten salt chlorination slag. The obtained concentrated brine has a low impurity content and a high NaCl concentration, and can be used in the chlor-alkali electrolysis process. - The treatment effect is good, and the Cl in the roasting material - The content is low and can be directly used in building materials, thus achieving resource recycling of other valuable metals.

[0055] Comparative Examples 1 and 2

[0056] The molten salt chloride slag in Example 1 was directly crushed and ground into powder, washed with industrial water and filtered, and then the filter residue was placed in a muffle furnace and calcined at 400-500° C. for 5 h. The specific implementation conditions of Comparative Examples 1 and 2 are shown in Table 4.

[0057] Table 4 Specific implementation of the comparative examples

[0058]

[0059] It can be seen from the embodiments and comparative examples that the temperature and time required for calcination in the technical solution of the present application are relatively low, and the chlorine content after calcination is even lower, indicating that after wet grinding and filtration by a ball mill, the NaCl in the chlorinated slag can fully enter the brine, thereby increasing the yield of NaCl, achieving a good calcination effect, and lowering energy consumption.

[0060] The embodiments described above are part of the embodiments of the present invention, rather than all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the application claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

Claims

1. A comprehensive treatment method for molten salt chlorinated slag, comprising collecting the molten salt chlorinated slag, grinding and beating the molten salt chlorinated slag to obtain chlorinated slag slurry, and separating the chlorinated slag slurry into solid slag and brine, wherein the solid slag is used for building materials and the brine is used for chlor-alkali electrolysis process, characterized in that: The grinding and beating of the molten salt chlorination slag are both carried out in a wet ball mill. The separation includes filtering the chlorination slag slurry twice after beating. The first filtration and the second filtration are both carried out using a vacuum belt filter with a negative pressure of 0.2 to 0.4 MPa and a filter screen with a specification of 1 to 5 μm. During the filtration process, industrial water is used for washing 2 to 3 times.

2. The comprehensive treatment method of molten salt chlorinated slag according to claim 1, characterized in that: The following steps are involved: S1: ball milling: collect the molten salt chlorination slag, add water, and ball mill and disperse it in a wet ball mill for 10 to 20 minutes, wherein the ore-to-slurry ratio is set to 1:3 to 1:4 to obtain chlorination slag slurry; S2: primary filtration: filtering the chlorinated residue slurry for the first time, washing with industrial water during filtration, obtaining a first filter residue and a first filtrate, wherein the first filter residue has a water content of 15-20wt%, and the first filter residue is used as a building material after roasting, and the first filtrate has a solid content of <1wt%, and a NaCl content of >30g / L; S3: adding alkali to adjust the slurry: adjusting the pH value of the first filtrate to 8-10 with alkali solution to obtain a first neutralized solution; S4: Secondary filtration: The first neutralized liquid is filtered for a second time, and industrial water is used for washing during the filtration process to obtain a second filter residue and a second filtrate, wherein the water content in the second filter residue is 20-30wt%, and the second filter residue is used as a building material after roasting, and the NaCl content in the second filtrate is greater than 15g / L; S5: neutralization by acid addition: adjusting the pH value of the second filtrate to 7-8 with acid to obtain a second neutralized solution, wherein the NaCl content is greater than 15 g / L; S6: Impurity removal: The second neutralized liquid is sequentially filtered and resin-coated to remove impurities, and then concentrated by a membrane concentration device to obtain concentrated brine, wherein the NaCl content in the concentrated brine is 20-50 g / L, and the concentration is adjusted to be used in the chlor-alkali electrolysis process.

3. The comprehensive treatment method of molten salt chlorinated slag according to claim 2, characterized in that: In S1, the ball loading amount of the wet ball mill is 25-30%.

4. The comprehensive treatment method of molten salt chlorinated slag according to claim 2, characterized in that: The amount of industrial water used in the first filtration of S2 is 1 to 2 times that of the chlorinated slag slurry.

5. The comprehensive treatment method of molten salt chlorinated slag according to claim 2, characterized in that: The amount of industrial water used in the second filtration of S4 is 0.5 to 1 times that of the first neutralization solution.

6. The comprehensive treatment method of molten salt chlorinated slag according to claim 2, characterized in that: The calcination in S2 and S4 is carried out in a tunnel kiln or a rotary kiln at a temperature of 300 to 500° C. for 4 to 5 hours.

7. The comprehensive treatment method of molten salt chlorinated slag according to claim 2, characterized in that: The alkaline solution in S3 is a sodium hydroxide solution, and the acid solution in S5 is a hydrochloric acid solution.

8. The comprehensive treatment method of molten salt chlorinated slag according to claim 2, characterized in that: The filter in S6 uses a 1-3 μm filter element, the resin tower uses a macroporous weakly acidic cation exchange resin with a particle size of 10-50 meshes, and the membrane concentration device uses a reverse osmosis membrane with a pore size of 0.8 nm.

9. The comprehensive treatment method of molten salt chlorinated slag according to claim 2, characterized in that: In S6, the concentration of the concentrated brine is adjusted with industrial salt to obtain saturated brine, and the content of NaCl in the saturated brine is controlled at 300±5g / L for use in the chlor-alkali electrolysis process.

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