A method for preparing barium chloride through barium slag

Abstract

The present invention relates to the technical field of preparation of barium chloride, and in particular to a method for preparing barium chloride by barium slag, comprising the following steps: S1, subjecting the barium slag to ball milling pretreatment; S2, mixing the pretreated barium slag with calcium chloride and carbon powder, and performing segmented high-temperature roasting to obtain a roasted product; S3, subjecting the roasted product to graded leaching treatment with hot water and dilute hydrochloric acid, filtering to obtain a leachate after the leaching treatment, concentrating and crystallizing to obtain a crude barium chloride product; S4, dissolving the crude barium chloride product in hot water, adding a coprecipitant and polyaspartic acid for aging treatment, filtering to obtain a filtrate after the aging treatment, and concentrating the filtrate by vacuum evaporation to obtain a pure barium chloride product. The present invention achieves efficient conversion of difficult-to-treat barium slag and precise separation of impurities through the process design of "segmented high-temperature roasting-graded leaching-coprecipitation purification", significantly improving the resource utilization rate of barium.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of barium chloride, and in particular to a method for preparing barium chloride by using barium slag. Background Art

[0002] Barium slag is an industrial waste product generated during the production of barium sulfate ore (witherite). Its primary components are insoluble barium compounds such as barium sulfate and barium silicate. It also contains inorganic metal impurities such as calcium, iron, strontium, magnesium, and aluminum, as well as small amounts of organic matter. These impurities typically exist as carbonates, sulfates, or silicates, such as calcium carbonate and iron oxide. Furthermore, barium slag contains aluminosilicate minerals such as silicon dioxide and some organic matter. Direct discharge of barium slag can cause severe environmental pollution. However, its rational utilization not only reduces environmental pressure but also recovers valuable barium resources, offering significant environmental and economic benefits.

[0003] Currently, the main technologies for preparing barium chloride from barium slag include acid leaching and chlorination roasting. Existing patent CN201110463000.1 discloses a method for preparing barium chloride from witherite tailings barium slag, belonging to the field of fine chemical technology. The method uses witherite tailings or barium slag as raw materials and uses a hydrochloric acid solution for two-step dissolution and leaching. The first step involves dissolving and removing impurities such as calcium, iron, and strontium in an ethanol-water medium at a low liquid-to-solid ratio. After filtration and separation, a solid phase containing insoluble substances such as barium and silicon is obtained. The second step is to dissolve the solid phase obtained in the first step at a higher liquid-to-solid ratio to obtain a barium chloride solution. After crystallization and drying, industrial-grade, qualified barium chloride can be obtained. Alternatively, oxalic acid can be added to the resulting barium chloride solution to adjust the pH, thereby precipitating and removing trace amounts of calcium and strontium. The solution is then concentrated and crystallized, and surface chlorides are washed away with anhydrous ethanol to obtain high-purity barium chloride. However, these existing technologies have obvious defects: in the acid leaching method, ethanol is expensive and difficult to recover, and the low liquid-to-solid ratio leaching in the first step makes it difficult to fully remove impurities; in the two-step acid leaching process, the loss of barium elements is relatively large and the recovery rate is not high; although the chlorination roasting method can convert insoluble barium compounds, the roasting efficiency is low, and the barium in the barium slag is difficult to fully convert into soluble barium chloride, and the product contains high levels of impurities such as calcium and strontium, which affects the product quality; in addition, both methods lack an efficient impurity removal mechanism, and the purity of the prepared barium chloride is limited, which is difficult to meet the market demand for high-purity barium chloride. Summary of the Invention

[0004] In view of this, the present invention proposes a method for preparing barium chloride by using barium slag to solve the technical problems of low recovery rate, poor impurity removal effect and low product purity in the barium slag treatment process in the prior art.

[0005] The technical solution of the present invention is achieved as follows: The present invention provides a method for preparing barium chloride by using barium slag, comprising the following steps:

[0006] S1, pre-treating the barium slag by ball milling;

[0007] S2, mixing the pretreated barium slag with calcium chloride and carbon powder, and performing staged high-temperature roasting to obtain a roasted product;

[0008] S3, the roasted product is subjected to graded leaching treatment with hot water and dilute hydrochloric acid. After the leaching treatment is completed, the leachate is filtered to obtain a leachate, which is concentrated and crystallized to obtain a crude barium chloride product;

[0009] S4. Dissolve the crude barium chloride in hot water, add a co-precipitant and polyaspartic acid to carry out aging treatment, and after the aging treatment is completed, filter to obtain a filtrate, and concentrate the filtrate by vacuum evaporation to obtain pure barium chloride.

[0010] The present invention improves the specific surface area and activity of barium slag through ball milling pretreatment, significantly improves the conversion efficiency of insoluble barium compounds in combination with a carbon powder-assisted staged high-temperature roasting process, realizes efficient and selective extraction of the barium element through graded leaching with hot water and dilute hydrochloric acid, and simultaneously forms an impurity removal system through the combined action of a synergistic precipitant (oxalic acid and trisodium ethylenediamine disuccinate) and polyaspartic acid, effectively reducing the content of impurities such as calcium and strontium in the product, ultimately achieving a high recovery rate of barium and a high purity of the barium chloride product; in addition, the present invention optimizes process parameters and operating steps, reduces energy consumption and raw material consumption, reduces wastewater discharge, and has a continuous and efficient process flow and is easy to operate, thereby having significant technical and economic benefits and being environmentally friendly, and being suitable for industrial production applications.

[0011] On the basis of the above technical solution, preferably, in step S1, the ball milling pretreatment includes: ball milling the barium slag at 20-25° C. for 1-2 hours, and controlling the particle size of the pretreated barium slag to be ≤200 mesh.

[0012] More preferably, the ball-to-material ratio is 4-5:1, and the ball milling medium is zirconium balls. The ball milling process increases the specific surface area and reaction activity of the barium slag, allowing the barium slag to come into contact with the chlorinating agent more fully, significantly improving the conversion rate of the insoluble barium compound during the subsequent roasting process.

[0013] Based on the above technical solution, preferably, in step S2, the mass ratio of barium slag, calcium chloride and carbon powder is 1:1-1.2:0.05-0.2.

[0014] On the basis of the above technical solution, preferably, in step S2, the staged high-temperature calcination includes: first performing a dehydration pretreatment at a temperature of 500-600°C for 0.5-1h, and then heating to 800-1000°C for reaction for 1-2h.

[0015] In the present invention, carbon powder is used as a reducing agent to promote the reaction and conversion of insoluble barium sulfate and calcium chloride, and at the same time, a reducing atmosphere is created to inhibit the oxidation of impurity elements such as iron and aluminum. A staged high-temperature roasting process is adopted to first complete dehydration pretreatment of the material in a medium-temperature zone to remove crystal water and adsorbed water and decompose some organic matter, thereby avoiding material splashing and adhesion caused by direct high temperature. Subsequently, a full chlorination reaction is carried out in the high-temperature zone, thereby significantly improving the conversion efficiency of the insoluble barium compound into soluble barium chloride.

[0016] Based on the above technical solution, preferably, in step S3, the graded leaching process includes:

[0017] S31, performing primary leaching on the roasted product with hot water at 60-80° C. at a solid-liquid ratio of 1:4-6, stirring for 1-1.5 hours, and filtering and separating to obtain a primary leachate and a primary filter residue;

[0018] S32. Add 1-2 mol / L dilute hydrochloric acid to the filter residue obtained in S31 at a solid-liquid ratio of 1:9-11, and leaching at 80-90°C for 1-2 hours. Filter to obtain a secondary leachate and a secondary filter residue, and combine the primary leachate and the secondary leachate to obtain a leachate.

[0019] Specifically, the first-stage hot water leaching mainly selectively dissolves the converted water-soluble barium chloride in the roasting product, which can dissolve most of the barium chloride under mild conditions while keeping insoluble impurities such as aluminosilicates in the solid phase, effectively achieving preliminary separation; the second-stage dilute hydrochloric acid leaching deeply dissolves the incompletely converted barium compounds remaining in the first-stage filter residue, promotes the dissolution and conversion of the remaining insoluble barium compounds through the acid medium, captures the barium loss during the hot water leaching process, and greatly improves the comprehensive recovery rate of barium.

[0020] Based on the above technical solution, preferably, in step S4, the amount of the co-precipitant added is 0.5-3% of the crude barium chloride product, and the amount of the polyaspartic acid added is 0.2-0.3% of the crude barium chloride product.

[0021] On the basis of the above technical solution, preferably, the co-precipitant is oxalic acid and trisodium ethylenediamine disuccinate in a mass ratio of 1:0.2-0.3.

[0022] Specifically, oxalic acid and trisodium ethylenediamine disuccinate achieved functional complementarity and synergistic efficiencies in impurity removal, with oxalic acid focusing on Sr 2+The first two compounds are used for precipitation removal, while trisodium ethylenediamine disuccinate preferably complexes metal ions such as iron ions, aluminum ions, and calcium ions. The two work together to expand the impurity removal spectrum. Secondly, polyaspartic acid forms a second layer of synergy with the first two compounds, which performs precipitation through surface activity to prevent large particle agglomeration and co-precipitation loss of barium ions. At the same time, polyaspartic acid is beneficial to the stability of the metal complex formed by trisodium ethylenediamine disuccinate, preventing the reversal of the complexation equilibrium. The three compounds work together to form a multi-dimensional synergistic system of "precipitation-chelation-dispersion", which minimizes the loss of target products and environmental load while ensuring efficient impurity removal.

[0023] On the basis of the above technical solution, preferably, in step S4, the aging treatment temperature is 75-85° C., and the aging treatment time is 0.5-1 h.

[0024] Based on the above technical solution, preferably, in step S4, before the filtrate is subjected to vacuum evaporation and concentration, an activated carbon treatment is further performed: 0.2-0.5% activated carbon is added to the filtrate, and adsorption is carried out at 60-70°C with stirring for 20-30 minutes, followed by filtration to remove the activated carbon. The activated carbon treatment selectively adsorbs residual organic impurities, pigments, and trace metal ion complexes in the solution, while simultaneously removing odors and potentially harmful substances in the solution, thereby significantly improving the purity and crystal quality of the barium chloride product.

[0025] The invention provides barium chloride prepared by a method for preparing barium chloride through barium slag.

[0026] The method for preparing barium chloride by using barium slag of the present invention has the following beneficial effects compared with the prior art:

[0027] (1) The present invention achieves efficient conversion of difficult-to-treat barium slag and precise separation of impurities through the process design of "staged high-temperature roasting-graded leaching-co-precipitation purification", overcoming the technical problems of low barium recovery rate, difficulty in impurity removal, and unstable product purity in traditional methods, significantly improving the resource utilization rate of barium and reducing environmental pollution, with obvious technical advantages and economic value;

[0028] (2) By introducing carbon powder as a multifunctional additive and adopting a staged high-temperature roasting process, the conversion efficiency and product quality of barium compounds were improved, and energy consumption and equipment wear were reduced. Through a hot water-hydrochloric acid graded leaching strategy, the graded extraction of barium and the preliminary separation of impurities were achieved based on the solubility differences of barium compounds, which not only improved the comprehensive recovery rate of barium but also reduced acid consumption and the burden of wastewater treatment.

[0029] (3) By constructing a collaborative purification system of "oxalic acid precipitation-trisodium ethylenediamine disuccinate chelation-polyaspartic acid dispersion", the oxalic acid was used to purify Sr 2+The selective precipitation, the preferential complexation of iron ions, aluminum ions and calcium ions by trisodium ethylenediamine disuccinate and the regulatory effect of polyaspartic acid on precipitation form a multi-dimensional impurity removal network, achieving efficient separation of alkaline earth metal and transition metal impurities while minimizing the loss of target products, which is beneficial to improving the purity of barium chloride. DETAILED DESCRIPTION

[0030] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] The barium slag in this example is barium slag from witherite tailings, and its main metal components and their mass fractions are: 28.35% barium carbonate, 15.34% barium sulfate, 13.25% silicon oxide, 4.01% aluminum, 2.91% calcium, 0.75% iron, and 0.72% strontium. Polyaspartic acid was purchased from Hubei Rishengchang New Material Technology Co., Ltd.

[0032] Example 1

[0033] This embodiment provides a method for preparing barium chloride using barium slag, comprising the following steps:

[0034] S1. Ball mill the barium slag at 25°C for 1.5h with a ball-to-material ratio of 4.5:1 and zirconium balls as the milling medium. The particle size of the pretreated barium slag is controlled to be ≤200 mesh.

[0035] S2, taking 100g of pretreated barium slag, 110g of calcium chloride, and 10g of carbon powder, mixing them, first dehydrating them at 550°C for 0.8h, then heating them to 900°C for 1.5h to obtain a calcined product;

[0036] S3, the roasted product was subjected to primary leaching with hot water at 70°C at a solid-liquid ratio of 1:5, stirred for 1.2 hours, and filtered to obtain a primary leachate and a primary filter residue; the obtained filter residue was added with 1.5 mol / L dilute hydrochloric acid at a solid-liquid ratio of 1:10, and leached at 85°C for 1.5 hours, and filtered to obtain a secondary leachate and a secondary filter residue, the primary leachate and the secondary leachate were combined to obtain a leachate, concentrated and crystallized to obtain crude barium chloride;

[0037] S4. Dissolve the crude barium chloride in 65°C deionized water at a solid-liquid ratio of 1:6.5, detect the pH value of the solution, and adjust it to pH=3-4; add 1.5% co-precipitant of crude quality and 0.25% polyaspartic acid of crude quality to the solution, wherein the co-precipitant is oxalic acid and trisodium ethylenediamine disuccinate in a mass ratio of 1:0.25, and age the solution. The aging temperature is 80°C and the aging time is 0.8h. After the aging treatment is completed, filter to obtain a filtrate, add activated carbon in an amount of 0.35% of the mass of the filtrate to the filtrate, stir and adsorb at 65°C for 25min, filter again to remove the activated carbon, adjust the pH to neutral, concentrate the filtrate by vacuum evaporation, cool and crystallize, and centrifuge to obtain barium chloride crystals, wash them with anhydrous ethanol 1-2 times, and dry them at 95°C for 3.5h to obtain pure barium chloride.

[0038] Example 2

[0039] This embodiment provides a method for preparing barium chloride using barium slag, comprising the following steps:

[0040] S1. Ball mill the barium slag at 20°C for 2 h with a ball-to-material ratio of 4:1 and zirconium balls as the milling medium. The particle size of the pretreated barium slag is controlled to be ≤200 mesh.

[0041] S2, taking 100g of pretreated barium slag, 100g of calcium chloride, and 5g of carbon powder, mixing them, first dehydrating them at 500°C for 1h, then heating them to 800°C for 2h to obtain a calcined product;

[0042] S3, the roasted product was subjected to primary leaching with 60 ° C hot water at a solid-liquid ratio of 1:4, stirred for 1.5 hours, and filtered to obtain a primary leachate and a primary filter residue; the obtained filter residue was added with 1 mol / L dilute hydrochloric acid at a solid-liquid ratio of 1:9, leached at 80 ° C for 2 hours, filtered to obtain a secondary leachate and a secondary filter residue, the primary leachate and the secondary leachate were combined to obtain a leachate, concentrated and crystallized to obtain crude barium chloride;

[0043] S4. Dissolve the crude barium chloride in deionized water at 60°C at a solid-liquid ratio of 1:5, detect the pH value of the solution, and adjust it to pH=3-4; add 0.5% co-precipitant of crude quality and 0.2% polyaspartic acid of crude quality to the solution, wherein the co-precipitant is oxalic acid and trisodium ethylenediamine disuccinate in a mass ratio of 1:0.2, and age the solution. The aging temperature is 75°C and the aging time is 1h. After the aging treatment is completed, filter to obtain a filtrate, add activated carbon in an amount of 0.2% by mass of the filtrate to the filtrate, stir and adsorb at 60°C for 30min, filter again to remove the activated carbon, adjust the pH to neutral, concentrate the filtrate by vacuum evaporation, cool and crystallize, and centrifuge to obtain barium chloride crystals, wash them with anhydrous ethanol 1-2 times, and dry them at 90°C for 4h to obtain pure barium chloride.

[0044] Example 3

[0045] This embodiment provides a method for preparing barium chloride using barium slag, comprising the following steps:

[0046] S1. Ball mill the barium slag at 25°C for 1 h with a ball-to-material ratio of 5:1 and zirconium balls as the milling medium. The particle size of the pretreated barium slag is controlled to be ≤200 mesh.

[0047] S2, taking 100g of pretreated barium slag, 120g of calcium chloride, and 20g of carbon powder, mixing them, first dehydrating them at 600°C for 0.5h, then heating them to 1000°C for 1h to obtain a calcined product;

[0048] S3, the roasted product was subjected to primary leaching with hot water at 80°C at a solid-liquid ratio of 1:6, stirred for 1 hour, and filtered to obtain a primary leachate and a primary filter residue; the obtained filter residue was added with 2 mol / L dilute hydrochloric acid at a solid-liquid ratio of 1:9, leached at 90°C for 1 hour, filtered to obtain a secondary leachate and a secondary filter residue, the primary leachate and the secondary leachate were combined to obtain a leachate, concentrated and crystallized to obtain crude barium chloride;

[0049] S4. Dissolve the crude barium chloride in deionized water at 70°C at a solid-liquid ratio of 1:8, detect the pH value of the solution, and adjust it to pH=3-4; add 3% co-precipitant of crude quality and 0.3% polyaspartic acid of crude quality to the solution, wherein the co-precipitant is oxalic acid and trisodium ethylenediamine disuccinate in a mass ratio of 1:0.3, and age the solution. The aging temperature is 85°C and the aging time is 1h. After the aging treatment is completed, filter to obtain a filtrate, add activated carbon in an amount of 0.5% of the mass of the filtrate to the filtrate, stir and adsorb at 70°C for 20min, filter again to remove the activated carbon, adjust the pH to neutral, concentrate the filtrate by vacuum evaporation, cool and crystallize, and centrifuge to obtain barium chloride crystals, wash them with anhydrous ethanol 1-2 times, and dry them at 100°C for 3h to obtain pure barium chloride.

[0050] Comparative Example 1

[0051] This comparative example provides a method for preparing barium chloride from barium slag, which is similar to Example 1 except that no carbon powder is added in step S2. The method specifically comprises:

[0052] S2. Take 100 g of pretreated barium slag and 110 g of calcium chloride, mix them, first dehydrate them at 550° C. for 0.8 h, then heat them to 900° C. and react for 1.5 h to obtain a calcined product.

[0053] Comparative Example 2

[0054] This comparative example provides a method for preparing barium chloride from barium slag, which is similar to Example 1 except that polyaspartic acid is not added in step S4. The method specifically comprises:

[0055] S4. Dissolve the crude barium chloride in 65°C deionized water at a solid-liquid ratio of 1:6.5, detect the pH value of the solution, and adjust it to pH=3-4; add 1.5% co-precipitant of crude quality to the solution, wherein the co-precipitant is oxalic acid and trisodium ethylenediamine disuccinate in a mass ratio of 1:0.25, and perform aging treatment. The aging temperature is 80°C, and the aging time is 0.8h. After the aging treatment is completed, filter to obtain a filtrate, add activated carbon in an amount of 0.35% of the filtrate mass to the filtrate, stir and adsorb at 65°C for 25min, filter again to remove the activated carbon, adjust the pH to neutral, concentrate the filtrate by vacuum evaporation, cool and crystallize, and centrifuge to obtain barium chloride crystals, wash with anhydrous ethanol 1-2 times, and dry at 95°C for 3.5h to obtain pure barium chloride.

[0056] Comparative Example 3

[0057] This comparative example provides a method for preparing barium chloride from barium slag, which is similar to Example 1 except that trisodium ethylenediamine disuccinate is not added in step S4. The method specifically comprises:

[0058] S4. Dissolve the crude barium chloride in 65°C deionized water at a solid-liquid ratio of 1:6.5, detect the pH value of the solution, and adjust it to pH=3-4; add 1.5% co-precipitant of crude quality and 0.25% polyaspartic acid of crude quality to the solution, wherein the co-precipitant is oxalic acid, and age the solution. The aging temperature is 80°C and the aging time is 0.8h. After the aging treatment is completed, filter to obtain a filtrate, add activated carbon in an amount of 0.35% of the filtrate mass to the filtrate, stir and adsorb at 65°C for 25min, filter again to remove the activated carbon, adjust the pH to neutral, concentrate the filtrate by vacuum evaporation, cool and crystallize, and centrifuge to obtain barium chloride crystals, wash with anhydrous ethanol 1-2 times, and dry at 95°C for 3.5h to obtain pure barium chloride.

[0059] Comparative Example 4

[0060] This comparative example provides a method for preparing barium chloride from barium slag, which is similar to Example 1 except that oxalic acid is not added in step S4. The method specifically comprises:

[0061] S4. Dissolve the crude barium chloride in deionized water at 65°C at a solid-liquid ratio of 1:6.5, detect the pH value of the solution, and adjust it to pH=3-4; add 1.5% co-precipitant of crude quality and 0.25% polyaspartic acid of crude quality to the solution, wherein the co-precipitant is trisodium ethylenediamine disuccinate, and perform aging treatment. The aging temperature is 80°C and the aging time is 0.8h. After the aging treatment is completed, filter to obtain a filtrate, add activated carbon in an amount of 0.35% of the mass of the filtrate to the filtrate, stir and adsorb at 65°C for 25min, filter again to remove the activated carbon, adjust the pH to neutral, concentrate the filtrate by vacuum evaporation, cool and crystallize, and centrifuge to obtain barium chloride crystals, wash with anhydrous ethanol 1-2 times, and dry at 95°C for 3.5h to obtain pure barium chloride.

[0062] Performance testing

[0063] According to the requirements of GB / T 1617-2014, "Industrial Barium Chloride," the purity of barium chloride and the contents of strontium (Sr), calcium (Ca), sulfide, iron (Fe), and water-insoluble matter were tested. The barium ion recovery rate was calculated. The barium content in the barium slag and barium chloride was determined gravimetrically. The barium ion recovery rate is the actual barium content in the recovered barium chloride divided by the barium content in the barium slag. The test results are shown in Table 1.

[0064] Table 1 Performance test data

[0065]

[0066] As shown in Table 1, experimental data indicates that the example product has a higher barium chloride content and barium ion recovery rate, while significantly reducing the impurity content and water-insoluble matter ratio. Comparative experiments fully demonstrate the necessity of each key technical point: the addition of carbon powder additive significantly improves the barium ion recovery rate; polyaspartic acid as a dispersing and regulating agent effectively reduces the impurities and water-insoluble matter content in the product; and the synergistic precipitation system of oxalic acid and trisodium ethylenediamine disuccinate is effective in selectively removing impurities, especially alkaline earth metals such as strontium and calcium, and transition metal impurities such as iron. Experimental results demonstrate that only by organically combining the steps of "ball milling pretreatment - staged roasting - graded leaching - synergistic purification" can a high-purity, low-impurity barium chloride product be obtained, demonstrating the systematic and innovative nature of the present process.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing barium chloride by using barium slag, characterized in that: The following steps are involved: S1, pre-treating the barium slag by ball milling; S2, mixing the pretreated barium slag with calcium chloride and carbon powder, and performing staged high-temperature roasting to obtain a roasted product; S3, the roasted product is subjected to graded leaching treatment with hot water and dilute hydrochloric acid. After the leaching treatment is completed, the leachate is filtered to obtain a leachate, which is concentrated and crystallized to obtain a crude barium chloride product; S4, dissolving the crude barium chloride in hot water, adding a co-precipitant and polyaspartic acid for aging, filtering to obtain a filtrate after the aging treatment, and concentrating the filtrate by vacuum evaporation to obtain pure barium chloride; The co-precipitant is oxalic acid and trisodium ethylenediamine disuccinate in a mass ratio of 1:0.2-0.

3.

2. The method for preparing barium chloride by using barium slag according to claim 1, wherein: In step S1, the ball milling pretreatment includes: ball milling the barium slag at 20-25° C. for 1-2 hours, and controlling the particle size of the pretreated barium slag to be ≤200 mesh.

3. The method for preparing barium chloride by using barium slag according to claim 1, wherein: In step S2, the mass ratio of barium slag, calcium chloride and carbon powder is 1:1-1.2:0.05-0.

2.

4. The method for preparing barium chloride by using barium slag according to claim 3, wherein: In step S2, the staged high-temperature calcination includes: first performing a dehydration pretreatment at a temperature of 500-600°C for 0.5-1h, and then heating to 800-1000°C for reaction for 1-2h.

5. The method for preparing barium chloride by using barium slag according to claim 1, wherein: In step S3, the graded leaching process includes: S31, performing primary leaching on the roasted product with hot water at 60-80° C. at a solid-liquid ratio of 1:4-6, stirring for 1-1.5 hours, and filtering and separating to obtain a primary leachate and a primary filter residue; S32. Add 1-2 mol / L dilute hydrochloric acid to the primary filter residue at a solid-liquid ratio of 1:9-11, and leaching at 80-90° C. for 1-2 h. Filter to obtain a secondary leachate, combine the primary leachate and the secondary leachate to obtain a leachate, concentrate and crystallize to obtain crude barium chloride.

6. The method for preparing barium chloride by using barium slag according to claim 1, wherein: In step S4, the amount of the co-precipitant added is 0.5-3% of the crude barium chloride product, and the amount of the polyaspartic acid added is 0.2-0.3% of the crude barium chloride product.

7. The method for preparing barium chloride by using barium slag according to claim 6, wherein: In step S4, the aging treatment temperature is 75-85° C., and the aging treatment time is 0.5-1 h.

8. The method for preparing barium chloride by using barium slag according to claim 1, wherein: In step S4, before the filtrate is subjected to vacuum evaporation and concentration treatment, an adsorption treatment is also included: 0.2-0.5% activated carbon is added to the filtrate, and adsorption is carried out at 60-70° C. with stirring for 20-30 minutes, and the activated carbon is removed by filtration.

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