Method for preparing barium chloride from barium slag

Abstract

The invention relates to the technical field of preparation of barium chloride, in particular to a method for preparing barium chloride from barium slag, which comprises the following steps: S1, carrying out ball milling pretreatment on the barium slag; s2, mixing the pretreated barium slag with calcium chloride and carbon powder, and performing segmented high-temperature roasting to obtain a roasted product; s3, the roasted product is subjected to graded leaching treatment with hot water and diluted hydrochloric acid, after leaching treatment is completed, leaching liquid is obtained through filtering, concentration and crystallization are conducted, and a crude barium chloride product is obtained; and S4, dissolving the crude barium chloride product in hot water, adding a synergistic precipitator and polyaspartic acid, carrying out aging treatment, after the aging treatment is completed, filtering to obtain a filtrate, and carrying out vacuum evaporation concentration on the filtrate to obtain a pure barium chloride product. According to the method, through the process design of sectional high-temperature roasting, graded leaching and collaborative precipitation purification, efficient conversion of the barium slag difficult to treat and precise separation of impurities are achieved, and the resource utilization rate of barium is remarkably increased.

Description

Technical Field

[0001] The present invention relates to the technical field of barium chloride preparation, and particularly to a method for preparing barium chloride from barium residue. Background Art

[0002] Barium residue is an industrial waste residue generated during the production of barium sulfate ore (witherite). Its main components are insoluble barium compounds such as barium sulfate and barium silicate, and it also contains inorganic metal impurities such as calcium, iron, strontium, magnesium, and aluminum, as well as a small amount of organic matter. These impurities usually exist in the form of carbonates, sulfates, or silicates, such as calcium carbonate and iron oxide. In addition, barium residue also contains aluminosilicate minerals such as silicon dioxide and some organic matter. If barium residue is directly discharged, it will cause serious environmental pollution. Reasonable utilization of barium residue can not only reduce environmental pressure but also recover valuable barium resources, with significant environmental and economic benefits.

[0003] Currently, the technologies for preparing barium chloride from barium residue mainly include acid leaching method and chlorination roasting method. The existing patent CN201110463000.1 discloses a method for preparing barium chloride from witherite tailing barium residue, belonging to the field of fine chemical technology. The method of the present invention uses witherite tailing or barium residue as raw materials and dissolves and leaches them in two steps with hydrochloric acid solution. In the first step, calcium, iron, strontium and other impurity elements are removed by dissolution at a lower liquid-solid ratio in an ethanol-water medium, and after filtration and separation, a solid phase containing insoluble substances such as barium and silicon is obtained; in the second step, a higher liquid-solid ratio is used to dissolve the solid phase obtained in the first step to obtain a barium chloride solution, and industrial-grade qualified barium chloride can be obtained after crystallization and drying. Or oxalic acid is added to the obtained barium chloride solution to adjust the pH value to precipitate trace calcium and strontium, and the solution is concentrated and crystallized, and the surface chloride is washed off with absolute ethanol to obtain barium chloride with higher purity. However, these existing technologies have obvious defects: in the acid leaching method, the cost of ethanol is high and it is difficult to recycle, and it is difficult to fully remove impurities by leaching at a low liquid-solid ratio in the first step; there is more loss of barium element during the two-step acid leaching process and the recovery rate is not high; although the chlorination roasting method can convert insoluble barium compounds, the roasting efficiency is low, it is difficult to fully convert barium in barium residue into soluble barium chloride, and the content of impurities such as calcium and strontium in the product is high, affecting the product quality; in addition, both methods lack an efficient impurity removal mechanism, and the purity of the prepared barium chloride is limited, making it 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 from barium residue to solve the technical problems of low recovery rate, poor impurity removal effect and low product purity in the process of barium residue treatment in the prior art.

[0005] The technical solution of the present invention is realized as follows: The present invention provides a method for preparing barium chloride from barium residue, including the following steps: S1. Ball-mill the barium slag for pretreatment; S2. Mix the pretreated barium slag with calcium chloride and carbon powder, and conduct staged high-temperature roasting to obtain a roasted product; S3. Perform fractional leaching treatment on the roasted product with hot water and dilute hydrochloric acid. After the leaching treatment, filter to obtain a leachate, concentrate and crystallize to obtain crude barium chloride; S4. Dissolve the crude barium chloride in hot water, add a co-precipitant and polyaspartic acid for aging treatment. After the aging treatment is completed, filter to obtain a filtrate, and the filtrate is concentrated by vacuum evaporation to obtain pure barium chloride.

[0006] In the present invention, ball-milling pretreatment improves the specific surface area and activity of the barium slag. The combined process of staged high-temperature roasting assisted by carbon powder significantly improves the conversion efficiency of poorly soluble barium compounds. The fractional leaching with hot water and dilute hydrochloric acid realizes the efficient and selective extraction of barium elements. At the same time, the combined action of the co-precipitant (oxalic acid and trisodium ethylenediaminedisuccinate) and polyaspartic acid forms an impurity removal system, effectively reducing the contents of impurities such as calcium and strontium in the product, and finally achieving a high recovery rate of barium and high purity of the barium chloride product. In addition, the present invention optimizes the process parameters and operation steps, reduces energy consumption and raw material consumption, reduces wastewater discharge, and the process flow is continuous, efficient and easy to operate, with significant technical and economic benefits and environmental friendliness, and is suitable for industrial production applications.

[0007] Based on the above technical solutions, preferably, in step S1, the ball-milling pretreatment includes: ball-milling the barium slag at 20 - 25 °C for 1 - 2 h, and controlling the particle size of the pretreated barium slag ≤ 200 mesh.

[0008] More preferably, the ball-to-material ratio is 4 - 5:1, and the ball-milling medium is zirconium balls. Through ball-milling treatment, the specific surface area and reaction activity of the barium slag are increased, making the barium slag contact more fully with the chlorinating agent, and greatly improving the conversion rate of poorly soluble barium compounds in the subsequent roasting process.

[0009] Based on the above technical solutions, preferably, in step S2, the mass ratio of the barium slag, calcium chloride and carbon powder is 1:1 - 1.2:0.05 - 0.2.

[0010] Based on the above technical solutions, preferably, in step S2, the staged high-temperature roasting includes: first performing dehydration pretreatment at 500 - 600 °C for 0.5 - 1 h, and then raising the temperature to 800 - 1000 °C for reaction for 1 - 2 h.

[0011] In the present invention, the toner acts as a reducing agent to promote the reaction conversion of insoluble barium sulfate and calcium chloride, and at the same time creates a reducing atmosphere to inhibit the oxidation of impurity elements such as iron and aluminum. The segmented high-temperature roasting process enables the material to first complete dehydration pretreatment in the medium-temperature zone, removing crystal water, adsorbed water and decomposing part of the organic matter, avoiding material splashing and adhesion caused by direct high temperature. Subsequently, a sufficient chlorination reaction is carried out in the high-temperature zone, significantly improving the conversion efficiency of insoluble barium compounds into soluble barium chloride.

[0012] On the basis of the above technical solutions, preferably, in step S3, the fractional leaching treatment includes: S31. First-stage leaching of the roasted product with hot water at 60-80 °C, with a solid-liquid ratio of 1:4-6, stirring for 1-1.5 h, and filtering to obtain a first-stage leachate and a first-stage filter residue; S32. Adding the filter residue obtained in S31 to 1-2 mol / L dilute hydrochloric acid according to a solid-liquid ratio of 1:9-11, leaching at 80-90 °C for 1-2 h, filtering to obtain a second-stage leachate and a second-stage filter residue, and combining the first-stage leachate and the second-stage leachate to obtain a leachate.

[0013] Specifically, the first-stage hot water leaching mainly selectively dissolves the converted water-soluble barium chloride in the roasted product, and can dissolve most of the barium chloride under mild conditions while keeping insoluble impurities such as silicate in the solid phase, effectively achieving preliminary separation. The second-stage dilute hydrochloric acid leaching then deeply dissolves the remaining unconverted barium compounds 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.

[0014] On the basis of the above technical solutions, preferably, in step S4, the addition amount of the co-precipitant is 0.5-3% of the crude barium chloride, and the addition amount of polyaspartic acid is 0.2-0.3% of the crude barium chloride.

[0015] On the basis of the above technical solutions, preferably, the co-precipitant is oxalic acid and trisodium ethylenediaminedisuccinate with a mass ratio of 1:0.2-0.3.

[0016] Specifically, oxalic acid and trisodium ethylenediaminedisuccinate achieve complementary functions and synergistic effects in impurity removal. Oxalic acid focuses on Sr 2+Precipitation removal, while trisodium ethylenediamine disuccinate preferably chelates metal ions such as iron ions, aluminum ions, and calcium ions. The two work synergistically to expand the impurity removal spectrum. Secondly, polyaspartic acid forms a second layer of synergy with the former two. Through surface activity, precipitation occurs to prevent large particle aggregation and coprecipitation 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 work together to form a "precipitation - chelation - dispersion" multi-dimensional synergistic system, which minimizes the loss of the target product and the environmental load while ensuring efficient impurity removal.

[0017] Based on the above technical solutions, preferably, in step S4, the temperature of the aging treatment is 75 - 85 °C, and the aging treatment time is 0.5 - 1 h.

[0018] Based on the above technical solutions, preferably, before the filtrate is subjected to vacuum evaporation and concentration treatment in step S4, it also includes activated carbon treatment: add 0.2 - 0.5% of activated carbon to the filtrate, stir and adsorb at 60 - 70 °C for 20 - 30 min, and filter to remove the activated carbon. Through activated carbon treatment, selectively adsorb residual organic impurities, pigment substances, and trace metal ion complexes in the solution, and at the same time remove the odor and potential harmful substances in the solution, significantly improving the purity and crystal quality of the barium chloride product.

[0019] The present invention provides barium chloride prepared by the method for preparing barium chloride from barium slag.

[0020] The method for preparing barium chloride from barium slag of the present invention has the following beneficial effects compared with the prior art: (1) Through the process design of "segmented high-temperature roasting - hierarchical leaching - synergistic precipitation purification", the present invention realizes the efficient conversion of refractory barium slag and precise separation of impurities, overcomes the technical problems such as low barium recovery rate, difficult impurity removal, and unstable product purity in traditional methods, significantly improves the resource utilization rate of barium, reduces environmental pollution, and has obvious technical advantages and economic value; (2) By introducing carbon powder as a multifunctional auxiliary agent and adopting a segmented high-temperature roasting process, the conversion efficiency of barium compounds and the product quality are improved, and the energy consumption and equipment wear are reduced; through the hot water - hydrochloric acid hierarchical leaching strategy, based on the solubility difference of barium compounds, the hierarchical extraction of barium and the preliminary separation of impurities are realized, which not only improves the comprehensive recovery rate of barium, but also reduces the acid consumption and the burden of wastewater treatment; (3) By constructing a synergistic purification system of "oxalic acid precipitation - trisodium ethylenediamine disuccinate chelation - polyaspartic acid dispersion", through oxalic acid for Sr 2+The selective precipitation, the preferential complexation of trisodium ethylenediaminedisuccinate with iron ions, aluminum ions, and calcium ions, and the regulation of precipitation by polyaspartic acid form a multi-dimensional and three-dimensional impurity removal network, achieving the efficient separation of alkaline earth metal and transition metal impurities, while minimizing the loss of the target product, which is beneficial to improving the purity of barium chloride. Detailed implementation manners

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in combination with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] In this embodiment, the barium slag is a baryte tailing barium slag, and its main metal components and their mass fractions are: barium carbonate 28.35%, barium sulfate 15.34%, silicon dioxide 13.25%, aluminum 4.01%, calcium 2.91%, iron 0.75%, strontium 0.72%. Polyaspartic acid is purchased from Hubei Rishengchang New Material Technology Co., Ltd.

[0023] Example 1 This embodiment provides a method for preparing barium chloride from barium slag, including the following steps: S1. Ball-mill the barium slag at 25°C for 1.5 h, with a ball-to-material ratio of 4.5:1, and the ball-milling medium is zirconium balls, controlling the particle size of the pretreated barium slag ≤ 200 mesh; S2. Take 100 g of the pretreated barium slag, 110 g of calcium chloride, and 10 g of carbon powder, first perform dehydration pretreatment at 550°C for 0.8 h, and then raise the temperature to 900°C and react for 1.5 h to obtain a calcined product; S3. Perform primary leaching of the calcined product with 70°C hot water, with a solid-to-liquid ratio of 1:5, stir for 1.2 h, filter and separate to obtain a primary leachate and a primary filter residue; add the obtained filter residue to 1.5 mol / L dilute hydrochloric acid according to a solid-to-liquid ratio of 1:10, leach at 85°C for 1.5 h, filter to obtain a secondary leachate and a secondary filter residue, and combine the primary leachate and the secondary leachate to obtain a leachate, concentrate and crystallize to obtain crude barium chloride; S4. Dissolve the crude barium chloride in deionized water at 65°C according to a solid-liquid ratio of 1:6.5, measure the pH value of the solution, and adjust it to pH = 3 - 4. Add 1.5% of the co-precipitant based on the mass of the crude product and 0.25% of polyaspartic acid based on the mass of the crude product to the solution. The co-precipitant is oxalic acid and trisodium ethylenediaminedisuccinate with a mass ratio of 1:0.25. Carry out aging treatment at a temperature of 80°C for 0.8 h. After the aging treatment is completed, filter to obtain a filtrate. Add 0.35% of activated carbon based on the mass of the filtrate to the filtrate, stir and adsorb at 65°C for 25 min, filter again to remove the activated carbon, adjust the pH to neutral. The filtrate is concentrated by vacuum evaporation, cooled and crystallized, and centrifuged to obtain barium chloride crystals. Wash with absolute ethanol 1 - 2 times and then dry at 95°C for 3.5 h to obtain pure barium chloride.

[0024] Example 2 This example provides a method for preparing barium chloride from barium slag, including the following steps: S1. Ball-mill the barium slag at 20°C for 2 h with a ball-to-material ratio of 4:1. The ball-milling medium is zirconia balls, and control the particle size of the pretreated barium slag to be ≤200 mesh. S2. Take 100 g of the pretreated barium slag, 100 g of calcium chloride, and 5 g of carbon powder and mix them. First, carry out dehydration pretreatment at 500°C for 1 h, and then raise the temperature to 800°C and react for 2 h to obtain a calcined product. S3. Leach the calcined product with hot water at 60°C for the first stage with a solid-liquid ratio of 1:4, stir for 1.5 h, filter and separate to obtain a first-stage leachate and a first-stage filter residue. Add 1 mol / L dilute hydrochloric acid to the obtained filter residue according to a solid-liquid ratio of 1:9, leach at 80°C for 2 h, filter to obtain a second-stage leachate and a second-stage filter residue. Combine the first-stage leachate and the second-stage leachate to obtain a leachate, concentrate and crystallize to obtain crude barium chloride. S4. Dissolve the crude barium chloride in deionized water at 60°C according to a solid-liquid ratio of 1:5, measure the pH value of the solution, and adjust it to pH = 3 - 4. Add 0.5% of the co-precipitant based on the mass of the crude product and 0.2% of polyaspartic acid based on the mass of the crude product to the solution. The co-precipitant is oxalic acid and trisodium ethylenediaminedisuccinate with a mass ratio of 1:0.2. Carry out aging treatment at a temperature of 75°C for 1 h. After the aging treatment is completed, filter to obtain a filtrate. Add 0.2% of activated carbon based on the mass of the filtrate to the filtrate, stir and adsorb at 60°C for 30 min, filter again to remove the activated carbon, adjust the pH to neutral. The filtrate is concentrated by vacuum evaporation, cooled and crystallized, and centrifuged to obtain barium chloride crystals. Wash with absolute ethanol 1 - 2 times and then dry at 90°C for 4 h to obtain pure barium chloride.

[0025] Example 3 This example provides a method for preparing barium chloride from barium slag, including the following steps: S1. Ball-mill the barium slag at 25 °C for 1 h with a ball-to-material ratio of 5:1. The ball-milling medium is zirconium balls, and control the particle size of the pretreated barium slag to be ≤200 mesh; S2. Take 100 g of the pretreated barium slag, 120 g of calcium chloride, and 20 g of carbon powder and mix them. First, perform dehydration pretreatment at 600 °C for 0.5 h, and then raise the temperature to 1000 °C and react for 1 h to obtain a calcined product; S3. Leach the calcined product with hot water at 80 °C for the first stage with a solid-to-liquid ratio of 1:6, stir for 1 h, and filter to separate to obtain a first-stage leachate and a first-stage filter residue; Add the obtained filter residue to 2 mol / L dilute hydrochloric acid according to a solid-to-liquid ratio of 1:9, leach at 90 °C for 1 h, filter to obtain a second-stage leachate and a second-stage filter residue, combine the first-stage leachate and the second-stage leachate to obtain a leachate, concentrate and crystallize to obtain crude barium chloride; S4. Dissolve the crude barium chloride in deionized water at 70 °C according to a solid-to-liquid ratio of 1:8, detect the pH value of the solution, and adjust it to pH = 3 - 4; Add 3% of the co-precipitant by the mass of the crude product and 0.3% of polyaspartic acid by the mass of the crude product to the solution, where the co-precipitant is oxalic acid and trisodium ethylenediaminedisuccinate with a mass ratio of 1:0.3, and perform aging treatment. The temperature of the aging treatment is 85 °C and the aging treatment time is 1 h. After the aging treatment is completed, filter to obtain a filtrate, add 0.5% of activated carbon by the mass of the filtrate to the filtrate, stir and adsorb at 70 °C for 20 min, filter again to remove the activated carbon, adjust the pH to neutral, evaporate and concentrate the filtrate under vacuum, cool and crystallize, and centrifuge to separate to obtain barium chloride crystals. After washing 1 - 2 times with absolute ethanol, dry at 100 °C for 3 h to obtain pure barium chloride.

[0026] Comparative Example 1 This comparative example provides a method for preparing barium chloride from barium slag, which is the same as Example 1 in detail, except that carbon powder is not added in step S2, specifically including: S2. Take 100 g of the pretreated barium slag and 110 g of calcium chloride and mix them. First, perform dehydration pretreatment at 550 °C for 0.8 h, and then raise the temperature to 900 °C and react for 1.5 h to obtain a calcined product.

[0027] Comparative Example 2 This comparative example provides a method for preparing barium chloride from barium slag, which is the same as Example 1 in detail, except that polyaspartic acid is not added in step S4, specifically including: S4. Dissolve the crude barium chloride in deionized water at 65°C according to 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% of the mass of the crude product of the co-precipitant to the solution, where the co-precipitant is oxalic acid and trisodium ethylenediaminedisuccinate with a mass ratio of 1:0.25. Conduct aging treatment at a temperature of 80°C for 0.8 h. After the aging treatment is completed, filter to obtain a filtrate. Add 0.35% of the mass of the filtrate of activated carbon to the filtrate, stir and adsorb at 65°C for 25 min, filter again to remove the activated carbon, adjust the pH to neutral. The filtrate is concentrated by vacuum evaporation, cooled and crystallized, and centrifuged to obtain barium chloride crystals. Wash with absolute ethanol 1 - 2 times and dry at 95°C for 3.5 h to obtain pure barium chloride.

[0028] Comparative Example 3 This comparative example provides a method for preparing barium chloride from barium slag, which is the same as Example 1 in detail, except that trisodium ethylenediaminedisuccinate is not added in step S4, specifically including: S4. Dissolve the crude barium chloride in deionized water at 65°C according to 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% of the mass of the crude product of the co-precipitant and 0.25% of the mass of the crude product of polyaspartic acid to the solution, where the co-precipitant is oxalic acid. Conduct aging treatment at a temperature of 80°C for 0.8 h. After the aging treatment is completed, filter to obtain a filtrate. Add 0.35% of the mass of the filtrate of activated carbon to the filtrate, stir and adsorb at 65°C for 25 min, filter again to remove the activated carbon, adjust the pH to neutral. The filtrate is concentrated by vacuum evaporation, cooled and crystallized, and centrifuged to obtain barium chloride crystals. Wash with absolute ethanol 1 - 2 times and dry at 95°C for 3.5 h to obtain pure barium chloride.

[0029] Comparative Example 4 This comparative example provides a method for preparing barium chloride from barium slag, which is the same as Example 1 in detail, except that oxalic acid is not added in step S4, specifically including: S4. Dissolve the crude barium chloride in deionized water at 65°C according to 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% of the mass of the crude product of the co-precipitant and 0.25% of the mass of the crude product of polyaspartic acid to the solution, where the co-precipitant is trisodium ethylenediaminedisuccinate. Conduct aging treatment at a temperature of 80°C for 0.8 h. After the aging treatment is completed, filter to obtain a filtrate. Add 0.35% of the mass of the filtrate of activated carbon to the filtrate, stir and adsorb at 65°C for 25 min, filter again to remove the activated carbon, adjust the pH to neutral. The filtrate is concentrated by vacuum evaporation, cooled and crystallized, and centrifuged to obtain barium chloride crystals. Wash with absolute ethanol 1 - 2 times and dry at 95°C for 3.5 h to obtain pure barium chloride.

[0030] Performance detection Detect the purity of barium chloride and the contents of strontium (Sr), calcium (Ca), sulfide, iron (Fe) and water-insoluble substances according to the relevant requirements of GB / T 1617—2014 "Industrial Barium Chloride", and calculate the recovery rate of barium ions. Determine the barium contents in barium slag and barium chloride respectively according to the gravimetric method. The barium ion recovery rate is the barium content in the actually recovered barium chloride / the barium content in the barium slag. The detection results are shown in Table 1.

[0031] Table 1 Performance detection data

[0032] As can be seen from Table 1, the experimental data show that the products of the examples have higher barium chloride content and barium ion recovery rate, while the impurity content and the proportion of water-insoluble substances are significantly reduced. The comparative tests fully prove the necessity of each key technical point: the addition of carbon powder additives significantly improves the barium ion recovery rate; polyaspartic acid as a dispersion regulator effectively reduces the impurity and water-insoluble substance contents in the products; the synergistic precipitation system of oxalic acid and trisodium ethylenediaminedisuccinate has an obvious selective removal effect on impurities, especially on the removal of alkaline earth metals such as strontium and calcium and transition metal impurities such as iron. The experimental results show that only by organically combining the links of "ball milling pretreatment - staged roasting - fractional leaching - synergistic purification" can high-purity and low-impurity barium chloride products be obtained, which reflects the systematicness and innovation of the process of the present invention.

[0033] The above is only the preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing barium chloride from barium slag, characterized in that: It includes the following steps: S1. Ball-mill and pre-treat the barium slag; S2. Mix the pre-treated barium slag with calcium chloride and carbon powder, and conduct staged high-temperature roasting to obtain a roasted product; S3. Perform staged leaching treatment on the roasted product with hot water and dilute hydrochloric acid. After the leaching treatment, filter to obtain a leachate, concentrate and crystallize to obtain crude barium chloride; S4. Dissolve the crude barium chloride in hot water, add a co-precipitant and polyaspartic acid for aging treatment. After the aging treatment is completed, filter to obtain a filtrate, and the filtrate is concentrated by vacuum evaporation to obtain pure barium chloride.

2. The method for preparing barium chloride from barium residue according to claim 1, characterized in that: In step S1, the ball-mill pre-treatment includes: ball-milling the barium slag at 20 - 25 °C for 1 - 2 h, and controlling the particle size of the pre-treated barium slag ≤ 200 mesh.

3. A method for preparing barium chloride from barium residue as described in claim 1, characterized in that: In step S2, the mass ratio of the barium slag, calcium chloride and carbon powder is 1:1 - 1.2:0.05 - 0.

2.

4. The method for preparing barium chloride from barium residue according to claim 3, characterized in that: In step S2, the staged high-temperature roasting includes: first perform dehydration pre-treatment at a temperature of 500 - 600 °C for 0.5 - 1 h, and then raise the temperature to 800 - 1000 °C and react for 1 - 2 h.

5. A method for preparing barium chloride from barium slag according to claim 1, characterized in that: In step S3, the staged leaching treatment includes: S31. Perform primary leaching on the roasted product with hot water at 60 - 80 °C, with a solid-liquid ratio of 1:4 - 6, stir for 1 - 1.5 h, filter and separate to obtain a primary leachate and a primary filter residue; S32. Add 1 - 2 mol / L dilute hydrochloric acid to the primary filter residue according to a solid-liquid ratio of 1:9 - 11, leach 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 from barium residue according to claim 1, characterized in that: In step S4, the addition amount of the co-precipitant is 0.5 - 3% of the crude barium chloride, and the addition amount of polyaspartic acid is 0.2 - 0.3% of the crude barium chloride.

7. A method for preparing barium chloride from barium slag as described in claim 6, characterized in that: The co-precipitant is oxalic acid and trisodium ethylenediaminedisuccinate with a mass ratio of 1:0.2 - 0.

3.

8. A method for preparing barium chloride from barium residue according to claim 6, characterized in that: In step S4, the temperature of the aging treatment is 75 - 85 °C, and the aging treatment time is 0.5 - 1 h.

9. The method for preparing barium chloride from barium residue according to claim 1, characterized in that: In step S4, before the filtrate is concentrated by vacuum evaporation, it also includes an adsorption treatment: add 0.2 - 0.5% of activated carbon to the filtrate, stir and adsorb at 60 - 70 °C for 20 - 30 min, and filter to remove the activated carbon.

10. Barium chloride prepared by the method for preparing barium chloride from barium slag according to any one of claims 1 - 9.

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