Method and device for harmless treatment of barium slag and co-production of barium carbonate

Abstract

The invention relates to the technical field of barium slag innocent treatment, in particular to a method and device for co-production of barium carbonate through barium slag innocent treatment, barium slag is crushed and sieved, and the particle size of barium slag powder is strictly controlled to be smaller than or equal to 5 mm; then barium slag powder and a hydrochloric acid solution are mixed, heated and stirred for a reaction, the contact area of the action of barium slag and the hydrochloric acid solution is increased, the leaching treatment efficiency of the hydrochloric acid solution is improved, and through plate-frame pressure filtration, pressure filtration liquid can be fully separated from the pressure filtration liquid, and a large number of available barium resources are promoted to enter the pressure filtration liquid; the content of soluble barium in press filter residues is reduced, the leaching rate of barium ions in harmless residues is reduced, and the harmlessness is reduced; the press filtrate is subjected to collaborative sedimentation treatment by adopting a precipitator and a flocculant, so that barium ions dissolved in the press filtrate are fully utilized to generate a barium carbonate product, and then the steps of washing and drying are performed, so that the quality of the barium carbonate product is improved, the additional value of the whole process is improved, and the harmless treatment cost of the barium slag is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of harmless treatment of barium slag, and particularly relates to a method and device for harmless treatment of barium slag with co-production of barium carbonate. Background Art

[0002] In the production process of barium salts, a large amount of barium slag is generated. For example, chemical production enterprises with barium salts such as barium carbonate and barium chloride as the main products discharge a large amount of barium slag every year. Such barium slag is mainly a mixture of barium sulfate that has not fully reacted in the process of preparing barium sulfide by high-temperature reduction of barite, residual barium sulfide, and heavy metal components such as lead, zinc, and strontium associated with barite. Therefore, barium slag has been listed in the "National Hazardous Waste List" (HW48 category). Open-air stacking not only occupies a large amount of land resources, but also causes serious pollution of the surrounding soil, groundwater, etc. due to the continuous leaching of heavy metals such as soluble barium ions, seriously affecting the ecological environment and even threatening the safety of human life.

[0003] Barium slag contains various elements such as Si, Al, Ba, Ca, Mg, O, and S. Among them, the Ba element mainly exists in the form of unreacted barium sulfate, barium carbonate, and barium sulfide in the barium slag, so that the barium slag still contains about 15-30% of recoverable barium element. Therefore, the harmless treatment of barium slag to recover the barium element resources in the barium slag has attracted the key attention of those skilled in the art.

[0004] At present, a large number of studies have been carried out on the harmless treatment methods and devices of barium slag, and relevant technical literatures have been formed. For example, the patent application No. 201911228669.5 discloses a method for harmless treatment of barium slag. The barium slag is finely ground by a wet ball mill, and the barium slag fine powder is treated with dilute nitric acid or dilute hydrochloric acid with a concentration of 12-18% for reaction. The tail gas generated during the reaction is used to produce sulfur; after filtration, the filtrate enters the reaction kettle after sedimentation, and is treated with barium hydroxide to clarify and prepare a mother liquor of barium nitrate or barium chloride with extremely high purity, and barium nitrate or barium chloride is obtained by evaporation and crystallization; or it is treated with sulfuric acid to generate a mother liquor of barium sulfate precipitate, and calcium chloride powder is added and mixed, and it is dried and used as a barium slag treatment product for cement clinker and commercial concrete. In this method, the purpose of harmless treatment of barium slag and recovery and utilization of barium resources in the barium slag is achieved. However, in this method, it is necessary to add dilute nitric acid or dilute hydrochloric acid with a relatively high concentration, and at the same time, it is necessary to add barium hydroxide or barium sulfate raw materials, resulting in a relatively high treatment cost, and it is necessary to introduce new barium element resources, resulting in a low recovery rate of barium element resources in the barium slag.

[0005] For another example, the patent No. 201910599664.7 discloses a non-toxic and resource-based treatment process for barium slag. The barium slag is soaked with clean water and / or leachate from the barium slag yard until the barium sulfide content in the barium slag is less than 0.1%. Then, the water-soluble barium slag is soaked in an acid medium (hydrochloric acid) until the barium carbonate content in the barium slag is less than 3%. Subsequently, the acid-soluble barium slag is soaked in desulfurized wastewater until the barium sulfide content in the barium slag is less than 1 ppm, and then pressure filtration is carried out to obtain a non-toxic barium slag product. This method requires a large amount of clean water or leachate for treatment before the acid medium treatment of barium slag, resulting in a large amount of waste liquid generated in the later stage of the harmless treatment of barium slag and a high cost. Moreover, the resource utilization rate of barium elements in barium slag is relatively low, and the treatment cycle is relatively long.

[0006] In summary, the existing technologies for the harmless treatment of barium slag and the resource utilization of barium elements in barium slag all have the following technical problems: the harmless treatment cycle of barium slag is relatively long, the cost is relatively high, and the resource utilization rate of barium elements is relatively low.

[0007] Based on this, in view of the technical defects in the harmless treatment of barium slag and the resource utilization of barium elements in barium slag in the existing technologies, the research team combines the harmless treatment of barium slag with the barium salt production process to realize the co-production of barium salt products while carrying out the harmless treatment of barium slag, reduce the cost of the harmless treatment of barium slag, improve the economic benefits of the harmless treatment of barium slag, and provide a new idea for the field of harmless treatment and resource utilization of barium slag. Summary of the Invention

[0008] Based on the above technical problems, the present invention provides a method and device for the harmless treatment of barium slag with co-production of barium carbonate. The specific technical solutions are as follows:

[0009] One of the purposes of the present invention is to provide a method for the harmless treatment of barium slag with co-production of barium carbonate, including the following steps:

[0010] S1: Crush and screen the barium slag to obtain barium slag powder with a particle size ≤ 5 mm;

[0011] S2: Mix the barium slag powder with a hydrochloric acid solution, heat and stir for reaction for 1 - 2 h, and perform plate and frame pressure filtration to obtain a pressure filtrate and a pressure filter residue; the filter residue is subjected to high-temperature calcination treatment until constant weight to obtain a harmless residue;

[0012] S3: Add a precipitant to the pressure filtrate to adjust the pH value to 8 - 10, add a flocculant, perform natural sedimentation treatment for 1 - 2 h, and filter to obtain a filter residue and a filtrate; the filtrate is sent to a wastewater treatment system for wastewater treatment;

[0013] S4: Wash the filter residue with water until the Cl - content < 0.01% to obtain washing wastewater and a filter cake; dry the filter cake until constant weight to obtain barium carbonate; the washing wastewater is recycled for washing and treating the filter residue.

[0014] The barium slag is crushed and sieved, and the particle size of the barium slag powder is strictly controlled to be ≤ 5 mm. Then, the barium slag powder is mixed with hydrochloric acid solution and heated with stirring for reaction, so as to increase the contact area between the barium slag and the hydrochloric acid solution, improve the leaching treatment efficiency of the hydrochloric acid solution, and through plate and frame pressure filtration, the pressure filtrate can be fully separated from the pressure filter residue, promoting a large amount of available barium resources to enter the pressure filtrate, reducing the soluble barium content in the pressure filter residue, reducing the leaching rate of barium ions in the harmless slag, and reducing the harmfulness. The pressure filtrate is subjected to co-settling treatment with a precipitant and a flocculant, so that the barium ions dissolved in the pressure filtrate are fully utilized to produce barium carbonate products, and then through washing and drying steps, the quality of the barium carbonate products is improved, the overall process added value is increased, and the cost of harmless treatment of barium slag is reduced.

[0015] In particular, through strict control of technical parameters such as the temperature, liquid-solid ratio, and hydrochloric acid concentration in the process of mixing the barium slag powder and the hydrochloric acid solution - heating and stirring, a large amount of soluble barium element resources can be promoted to enter the solution under the conditions of low hydrochloric acid solution concentration and low reaction temperature, reducing the content of soluble barium element resources in the barium slag, which not only helps to improve the harmless treatment effect of barium slag, but also ensures the quality of subsequent produced barium carbonate products.

[0016] Preferably, the mass percentage concentration of the hydrochloric acid solution is 5 - 10%, and the barium slag powder and the hydrochloric acid solution are in a solid-liquid mass ratio of 1:3 - 1:5; the heating and stirring reaction is carried out with a stirring speed of 300 - 400 r / min and heated to a temperature of 50 - 70 °C for reaction.

[0017] More preferably, the mass percentage concentration of the hydrochloric acid solution is 8%, and the barium slag powder and the hydrochloric acid solution are in a solid-liquid mass ratio of 1:5; the heating and stirring reaction is carried out with a stirring speed of 300 - 400 r / min and heated to a temperature of 60 °C for reaction.

[0018] In order to promote the decrease of the water content in the barium slag and enable the volatilization of residual volatile components such as hydrochloric acid in the barium slag to ensure subsequent building material utilization, preferably, the high-temperature calcination temperature is 200 - 400 °C. More preferably, the tail gas generated during the high-temperature calcination first passes through water spray to absorb chloride ions and / or sulfate ions and then enters the next process.

[0019] In the present invention, the precipitant is one or both of sodium carbonate and sodium bicarbonate; and the flocculant is polyaluminum oxide accounting for 0.1% of the mass of the pressure filtrate. By using barium ions to generate barium carbonate precipitation with carbonate or bicarbonate ions in the solution obtained by leaching barium slag with hydrochloric acid solution, the recovery rate of barium element resources is improved, the added value of barium carbonate products is increased, and the cost of the process for co-producing barium carbonate by harmless treatment of barium slag is reduced.

[0020] Preferably, the filter cake drying is carried out at a temperature of 100-120°C.

[0021] The second object of the present invention is to provide a device for harmless treatment of barium slag and co-production of barium carbonate, which includes a raw slag bin, a crusher, a filter, and a reaction kettle. A belt conveyor A is provided between the raw slag bin and the crusher; a vibrating screen is provided at the bottom of the crusher, and a belt conveyor B is provided between the bottom of the vibrating screen and the reaction kettle; a hydrochloric acid solution tank is connected to the reaction kettle through a pipeline; a plate and frame filter press is provided at the bottom of the reaction kettle, and a flocculation sedimentation tank is connected to the bottom of the plate and frame filter press through a pipeline, and the plate and frame filter press is connected to a calcination furnace through a belt conveyor D; the calcination furnace is connected to a harmless slag bin through a belt conveyor E; the bottom of the flocculation sedimentation tank is connected to the filter, the filter is connected to a washing tank through a belt conveyor F, the washing tank is connected to a drying tower through a belt conveyor G, and the drying tower is connected to a barium carbonate bin through a belt conveyor H.

[0022] By reasonably connecting the equipment for harmless treatment of barium slag and co-production of barium carbonate, such as the raw slag bin, crusher, filter, reaction kettle, vibrating screen, hydrochloric acid solution tank, plate and frame filter press, flocculation sedimentation tank, calcination furnace, harmless slag bin, washing tank, drying tower, and barium carbonate bin, it helps to realize the continuous production of barium slag harmless treatment and co-production of barium carbonate products. And by appropriately controlling the aperture of the vibrating screen, the temperature, stirring speed, liquid-solid mass ratio that can be maintained in the reaction kettle, and the appropriate control of the hydrochloric acid concentration in the hydrochloric acid solution tank, the treatment efficiency and effect of the barium slag harmless treatment and co-production of barium carbonate process are greatly improved. The harmless treatment cycle of barium slag can be shortened to within 5 hours, the barium ion leaching rate in the harmless slag obtained from barium slag treatment drops to 2 mg / L, and through the flocculation precipitation treatment in the flocculation sedimentation tank, the barium element resources in the filtrate are fully utilized, so that the barium resource recovery rate in barium slag reaches more than 95%, the purity of the obtained barium carbonate product is ≥98.5%, and at the same time, the detection rate of barium element in the filtrate for recovering barium carbonate is <1 mg / L, realizing the recycling of barium element resources in barium slag, improving the added value of barium slag harmless treatment, and reducing the cost of barium slag harmless treatment.

[0023] In order to realize the recycling of washing wastewater and reduce the waste of water resources, preferably, a washing wastewater tank is provided at the bottom of the washing tank, and a circulation pipe is provided between the washing wastewater tank and the washing tank; in order to be able to carry out harmless treatment and emptying of the filtrate for recovering barium carbonate, preferably, the bottom of the filter is connected to a wastewater treatment system through a pipeline. In order to better reduce the consumption of water resources, the bottom of the filter is connected to a wastewater treatment system through a pipeline, and the wastewater treatment system is communicated with the washing wastewater tank through a pipeline.

[0024] In order to reduce energy consumption and make full use of the waste heat generated by the calciner to dry barium carbonate products, preferably, a hot gas recycling pipeline is provided between the calciner and the drying tower.

[0025] In order to ensure the crushing effect of barium slag and reduce the sieving difficulty of the vibrating screen, preferably, the crusher is a jaw crusher, and the aperture of the sieve holes of the vibrating screen is 5 mm.

[0026] In order to ensure the mixing - heating and stirring reaction treatment effect and efficiency of barium slag powder and hydrochloric acid solution, preferably, a temperature sensor is provided in the reaction kettle, a liquid metering valve is provided between the reaction kettle and the hydrochloric acid solution tank, a weighing scale is provided between the reaction kettle and the vibrating screen, and a programmable controller is provided on the reaction kettle. The programmable controller is connected to the temperature sensor, the liquid metering valve, and the weighing scale. The programmable controller is used to control the temperature in the reaction kettle to be maintained at 50 - 70 °C. At the same time, the programmable controller is used to control the opening degree of the liquid metering valve according to the weighing result of the weighing scale, so as to control the solid - liquid mass ratio of the barium slag powder and the hydrochloric acid solution entering the reaction kettle to be 1:3 - 1:5.

[0027] In order to be able to convey the screened materials on the screen surface of the vibrating screen to the original slag bin or to the crusher for secondary crushing, preferably, a discharge port is provided on the screen surface of the vibrating screen, and a belt conveyor C is provided at the bottom of the discharge port. In order to avoid shoveling from the original slag bin 1 onto the belt conveyor A again, preferably, the belt conveyor C is connected to the belt conveyor A and can convey the screened materials on the vibrating screen surface to the belt conveyor A.

[0028] Compared with the prior art, the technical effects of the present invention are as follows:

[0029] The barium slag is subjected to crushing - sieving - hydrochloric acid leaching reaction treatment, and the treatment conditions of the hydrochloric acid leaching reaction are strictly controlled, and processes such as pressure filtration are carried out, so that the soluble barium element resources in the barium slag enter the pressure filtrate, reducing the soluble barium element resources in the pressure filter residue. Then, through high - temperature calcination treatment, the volatilization of chloride ions is reduced, and the harm of the harmless slag is reduced, so that the leaching rate of barium ions in the harmless slag drops to 2 mg / L; at the same time, the pressure filtrate is jointly treated with a precipitant - flocculant - filtration, so that the barium ions in the pressure filtrate are converted into precipitates and barium carbonate products are generated, so that the recovery rate of barium element resources reaches more than 95%, and the purity of barium carbonate reaches more than 98.5%, greatly improving the product added value, reducing the content of barium element resources in the filtrate, and reducing the barium ion concentration to less than 1 mg / L.

[0030] The technological process of the present invention is simple and easy to operate. Description of the Drawings

[0031] In order to enable those skilled in the art to fully understand the technical solution of the present invention, the following explanations are made on the provided drawings in combination with the content of the technical solution.

[0032] Figure 1 It is the process flow chart of the present invention.

[0033] Figure 2 It is the schematic diagram of the connection relationship of the device and equipment of the present invention.

[0034] Figure 3 It is the schematic diagram of the connection relationship between the crusher and the vibrating screen of the present invention.

[0035] Figure 4 It is the test sample inspection report of the present invention.

[0036] 1 - Original slag bin 2 - Crusher 3 - Vibrating screen 4 - Reactor 5 - Plate and frame filter press 6 - Calcining furnace 7 - Harmless slag bin 8 - Flocculation sedimentation tank 9 - Filter 10 - Washing tank 11 - Drying tower 12 - Barium carbonate bin 13 - Belt conveyor A 14 - Crushing outlet 15 - Belt conveyor B 16 - Belt conveyor C. Specific embodiments

[0037] In order to facilitate those skilled in the art to correctly understand the present invention and enable them to fully understand the technical content of the present invention, the following further elaborates on the technical solution of the present invention in combination with specific embodiments and drawings. However, this elaboration does not limit the scope of protection required by the present invention. Those skilled in the art's understanding of the protection scope of the present invention cannot be limited to the following elaboration content only. Any equivalent replacement or change made by those skilled in the art or those familiar with the technology in the art based on the technical solution and inventive concept of the present invention should be covered within the protection scope of the present invention.

[0038] Such as Figure 2 、 Figure 3As shown, in some embodiments, the device for harmless treatment of barium slag and co-production of barium carbonate includes a raw slag bin 1, a crusher 2, a filter 9, and a reaction kettle 4. A belt conveyor A 13 is provided between the raw slag bin 1 and the crusher 2; a vibrating screen 3 is provided at the bottom of the crusher 2, and a belt conveyor B 15 is provided between the bottom of the vibrating screen 3 and the reaction kettle 4; a hydrochloric acid solution tank is connected to the reaction kettle 4 through a pipeline; a plate and frame filter press 5 is provided at the bottom of the reaction kettle 4, and the bottom of the plate and frame filter press 5 is connected to a flocculation sedimentation tank 8 through a pipeline, and the plate and frame filter press 5 is connected to a calcination furnace 6 through a belt conveyor D; the calcination furnace 6 is connected to a harmless slag bin 7 through a belt conveyor E; the bottom of the flocculation sedimentation tank 8 is connected to the filter 9, the filter 9 is connected to a washing tank 10 through a belt conveyor F, the washing tank 10 is connected to a drying tower 11 through a belt conveyor G, and the drying tower 11 is connected to a barium carbonate bin 12 through a belt conveyor H.

[0039] When in use, as Figure 1 and Figure 3 shown, use a forklift to shovel the barium slag in the raw slag bin 1 onto the belt conveyor A 13, so that it is conveyed into the crusher 2 under the action of the belt conveyor A 13 for crushing, and discharged from the crushing outlet 14, and vibrated and screened through the vibrating screen 3 provided at the bottom (the screen hole diameter is 5 mm). The screened material can be returned to the crusher 2 through the belt conveyor C 16 for cyclic crushing. The screened bottom material is the crushed barium slag powder, and the particle size of the barium slag powder is ≤ 5 mm; then use the belt conveyor B 15 to convey the barium slag powder into the reaction kettle 4, and at the same time convey the hydrochloric acid solution in the hydrochloric acid solution tank into the reaction kettle 4 through a pipeline to mix with the barium slag powder, control the solid-liquid mass ratio of the mixture to be 1:3 - 5, the temperature in the reaction kettle 4 is 50 - 70 °C, and the stirring speed is 300 - 400 r / min. After stirring and reacting for 1 - 2 h, then send the slurry discharged from the reaction kettle 4 into the plate and frame filter press 5, control the filter pressure of the plate and frame filter press to be 0.6 MPa and filter for 60 min to obtain filtrate and filter residue; the filter residue is conveyed to the calcination furnace 6 through the belt conveyor D, control the temperature to be 200 - 400 °C and calcine until constant weight to obtain harmless slag, and convey the harmless slag to the harmless slag bin 7 through the belt conveyor E for storage, for later use or sent to the building material product preparation process; the filtrate is conveyed into the flocculation sedimentation tank 8 through a pipeline, add a precipitant (sodium carbonate) to adjust the pH value to 8 - 10, and at the same time add 0.1% of polyaluminum oxide based on the mass of the filtrate, mix evenly, and naturally settle for 1 - 2 h, and filter through the filter 9 (centrifugal separator) to obtain filtrate and filter residue; the filtrate is sent to the wastewater treatment system for treatment, and the filter residue is conveyed to the washing tank 10 through the belt conveyor F, and washed with clean water or the circulating liquid obtained by treating the wastewater treatment system until Cl -The content is < 0.01%, obtaining washing wastewater and filter cake; the filter cake is conveyed to the drying tower 11 by a belt conveyor G and dried to a constant weight to obtain barium carbonate. The barium carbonate is conveyed to the barium carbonate storage by a belt conveyor H for standby use. After the harmless treatment of the barium residue to form harmless residue, the filtrate generated during the harmless treatment process is recycled to recover barium element resources to produce barium carbonate products, which improves the added value of the barium residue harmless treatment process and reduces the cost of barium residue harmless treatment.

[0040] As Figure 2 shown, in some embodiments, a washing wastewater tank is provided at the bottom of the washing tank 10, and a circulation pipe is provided between the washing wastewater tank and the washing tank 10; the washing wastewater discharged from the washing tank 10 can be used to circulate and wash the filter cake through the circulation pipe, reducing the consumption of water resources and cost. In some embodiments, the bottom of the filter press 9 is connected to a wastewater treatment system through a pipeline to achieve the harmless treatment and discharge of the waste liquid. In some embodiments, the bottom of the filter press 9 is connected to a wastewater treatment system through a pipeline, and the wastewater treatment system is communicated with the washing wastewater tank through a pipeline, so that the filtrate generated by filtration is returned to the washing tank 10 for circulating washing and utilization after being treated by the wastewater treatment system (reducing the chloride ion content to < 0.01%), reducing the cost of water resources.

[0041] As Figure 2 shown, in some embodiments, a hot gas circulation utilization pipeline is provided between the calcining furnace 6 and the drying tower 11. The hot gas generated by the calcining furnace can be fully utilized to reduce energy consumption. In some embodiments, the crusher 2 is a jaw crusher, and the aperture of the sieve holes of the vibrating screen 3 is 5 mm, which helps to reduce the difficulty of barium residue crushing treatment.

[0042] In some embodiments, a temperature sensor is provided in the reaction kettle 4, a liquid metering valve is provided between the reaction kettle 4 and the hydrochloric acid solution tank, a weighing scale is provided between the reaction kettle 4 and the vibrating screen 3, and a programmable logic controller (PLC controller) is provided on the reaction kettle 4. The programmable logic controller is connected to the temperature sensor, the liquid metering valve, and the weighing scale. The programmable logic controller (PLC controller) is used to control the temperature in the reaction kettle to be maintained at 50 - 70 °C. At the same time, the programmable logic controller is used to control the opening degree of the liquid metering valve according to the weighing result of the weighing scale, so as to control the solid-liquid mass ratio of the barium residue powder and the hydrochloric acid solution entering the reaction kettle to be 1:3 - 1:5.

[0043] As Figure 3As shown, in some embodiments, a discharge port is provided on the screen surface of the vibrating screen 3, and a belt conveyor C16 is provided at the bottom of the discharge port. The screen material on the screen surface of the vibrating screen 3 can be conveyed to the original slag bin 1 or conveyed into the crusher 2 for secondary crushing. In some embodiments, the belt conveyor C16 is connected to the belt conveyor A13 and can convey the screen material on the screen surface of the vibrating screen 3 onto the belt conveyor A13.

[0044] In order to better verify the technical effects that the present invention can bring, the research team of the present invention used the above device for harmless treatment of barium slag and co-production of barium carbonate to conduct the following tests on the harmless treatment of barium slag:

[0045] Test 1 Influence of different leaching conditions on the leaching rate of soluble barium in barium slag

[0046] Using the above vibrating screen with a screen hole diameter of 5 mm for crushing barium slag to obtain barium slag powder; mixing the barium slag powder with a hydrochloric acid solution with a mass concentration of A according to a solid-liquid ratio of B, controlling the temperature at C, controlling the stirring speed between 300 - 400 r / min for stirring treatment D, and using a plate and frame filter press to filter at 0.6 MPa for 60 min to obtain filtrate and filter residue.

[0047] Adjust and test the mass concentration (%) of the hydrochloric acid solution, the solid-liquid ratio, the temperature (°C), and the treatment time (h) according to Table 1 below, and detect the leaching rate (%) of soluble barium in the treated barium slag for each group (each group is detected three times and the average value is taken), and record the detection results in Table 1 below.

[0048] Table 1

[0049]

[0050] Perform a full-factor range analysis on the data obtained in Table 1, and the results are shown in Table 2 below:

[0051] Table 2

[0052]

[0053]

[0054] Note:

[0055] ① The mean values corresponding to factors A from level 1 to level 4 are the average leaching rates obtained when the hydrochloric acid concentration is 3%, 5%, 8%, and 10%, and the other factors (B, C, D) vary according to Table 1.

[0056] ② The mean values corresponding to factors B from level 1 to level 4 are the average leaching rates obtained when the solid-liquid ratio is 1:3, 1:5, 1:8, and 1:10, and the other factors (A, C, D) vary according to Table 1.

[0057] ③The average value of levels 1 to 4 corresponding to factor C is the average value of the leaching rates obtained when the temperature is 40°C, 50°C, 60°C, and 70°C, and the other factors (A, B, D) vary according to Table 1.

[0058] ④The average value of levels 1 to 4 corresponding to factor D is the average value of the leaching rates obtained when the temperature is 0.5 h, 1.0 h, 1.5 h, and 2.0 h, and the other factors (A, B, C) vary according to Table 1.

[0059] As can be seen from Table 1 and Table 2, controlling the temperature, solid-liquid ratio, time, and hydrochloric acid concentration during the mixed leaching of barium slag powder and hydrochloric acid solution will affect the leaching rate of soluble barium in the barium slag powder. When the hydrochloric acid concentration is controlled at 5-10%, the solid-liquid ratio during the leaching process is controlled at 1:3-5, the temperature is 50-70°C, and the time is 1-2 h, it can help improve the leaching rate of soluble barium elements, reduce the leaching rate of soluble barium elements in the filter cake obtained by plate and frame filter press filtration, improve the safety of the filter cake, and reduce the harm of harmless slag. And through the range analysis of factors, it is known that when the hydrochloric acid concentration is controlled at 8%, the solid-liquid ratio is controlled at 1:5, the temperature is controlled at 60°C, and the time is controlled at 2 h, it can help improve the leaching rate of soluble barium elements in the barium slag, and then reduce the content of soluble barium elements in the filter cake and improve the safety.

[0060] Experiment 2 Influence of Different Processes on the Harmless Treatment Effect and the Quality of Co-produced Barium Salt

[0061] Example 1

[0062] On the basis of Experiment 1, the barium slag powder is mixed with a hydrochloric acid solution with a mass percentage concentration of 8% according to a solid-liquid ratio of 1:3, the temperature is controlled at 60°C, and the stirring speed is between 300-400 r / min and stirred for 2 h, and then treated by plate and frame filter press filtration to obtain a filter cake and a filtrate; the pH value of the filtrate is adjusted to be between 8-10 with sodium carbonate, and 0.1% of polyaluminum chloride based on the mass of the filtrate is added as a flocculant and stirred evenly, and then naturally settled for 1 h and filtered to obtain a filter cake and a filtrate.

[0063] Example 2

[0064] On the basis of Experiment 1, the barium slag powder is mixed with a hydrochloric acid solution with a mass percentage concentration of 8% according to a solid-liquid ratio of 1:5, the temperature is controlled at 60°C, and the stirring speed is between 300-400 r / min and stirred for 2 h, and then treated by plate and frame filter press filtration to obtain a filter cake and a filtrate; the pH value of the filtrate is adjusted to be between 8-10 with sodium carbonate, and 0.1% of polyaluminum chloride based on the mass of the filtrate is added as a flocculant and stirred evenly, and then naturally settled for 2 h and filtered to obtain a filter cake and a filtrate.

[0065] Example 3

[0066] On the basis of Experiment 1, barium slag powder was mixed with hydrochloric acid solution with a mass percentage concentration of 8% at a solid-liquid ratio of 1:5, and the temperature was controlled at 70 °C and the stirring speed was between 300 - 400 r / min for stirring treatment for 1.5 h. Then, plate and frame filter press filtration treatment was carried out to obtain filter press residue and filtrate; the pH value of the filtrate was adjusted to be between 8 - 10 with sodium carbonate, and natural sedimentation treatment was carried out for 1 h, followed by filtration to obtain filter residue and filtrate.

[0067] 1. Influence of different treatment processes on the harmless treatment effect

[0068] The barium slag powder, the obtained filter press residue, and filtrate used in Examples 1 to 3 were subjected to detection of copper, zinc, barium, lead, cadmium, total chromium, nickel, iron, mercury, arsenic, and selenium, and the detection results were recorded in Table 3.

[0069] Table 3 (unit: mg / L)

[0070]

[0071] Note:

[0072] ② The detection and treatment of barium slag powder and filter press residue were carried out after treatment with reference to GB5085.3 - 2007.

[0073] ② "ND" indicates not detected because it is lower than the detection limit.

[0074] As can be seen from Table 3, after the mixed leaching treatment of barium slag powder and hydrochloric acid solution, the leaching rate of soluble barium in the filter press residue obtained by plate and frame filter press filtration decreased to less than 1.5 mg / L, greatly reducing the harmfulness of the harmless slag. At the same time, after carbonization precipitation - flocculation treatment and then filtration, the soluble barium element entering the filtrate was recycled, reducing the content of soluble barium element in the filtrate to less than 1 mg / L, increasing the recovery rate of soluble barium resources in barium slag (more than 99.95%), and reducing the cost of harmless treatment of barium slag.

[0075] 2. Influence of different treatment processes on the quality of barium carbonate products

[0076] The filter residue obtained in Examples 1 to 3 was washed with clear water until the Cl - content < 0.01% to obtain washing wastewater and filter cake; the filter cake was dried to constant weight at a temperature between 100 - 120 °C to obtain barium carbonate products, and the purity and whiteness of the barium carbonate products were analyzed, and the results are shown in Table 4 below.

[0077] Table 4

[0078]

[0079] As can be seen from Table 4, the purity of the barium carbonate product obtained by the present invention can reach over 98%, and the whiteness can reach over 92%, which can meet the requirements of industrial applications and can be used for direct sales, greatly improving the added value of the harmless treatment process of barium slag.

[0080] In addition, in the present invention, the pressure and pressure filtration time during the pressure filtration process of the plate and frame filter press are monitored, and the moisture content of the corresponding pressure filtration residue is detected. The samples obtained by controlling the pressure filtration pressure of the plate and frame filter press at 0.4 MPa for 30 min, 45 min, and 60 min are sequentially labeled as pressure filtration residue 40-30, pressure filtration residue 40-45, and pressure filtration residue 40-60; the samples obtained by controlling the pressure filtration pressure of the plate and frame filter press at 0.6 MPa for 30 min, 45 min, and 60 min are sequentially labeled as pressure filtration residue 50-30, pressure filtration residue 50-45, and pressure filtration residue 50-60; the samples obtained by controlling the pressure filtration pressure of the plate and frame filter press at 0.8 MPa for 30 min, 45 min, and 60 min are sequentially labeled as pressure filtration residue 60-30, pressure filtration residue 60-45, and pressure filtration residue 60-60; and the moisture content of the pressure filtration residue is detected, and it is found that: with the prolongation of time and the increase of pressure, it will help to reduce the moisture content in the pressure filtration residue, so that the filtrate can be more thoroughly filtered out, which helps to reduce the content of soluble barium ions in the barium slag.

[0081] For other matters not covered in the present invention, reference can be made to the prior art or the common general knowledge well-known to those skilled in the art, and they can be realized by conventional technical means. For example, the barium slag is crushed and sieved into powder with a particle size of ≤5 mm, and the installation method of connecting the equipment into the entire device system, etc.

Claims

1. A method for harmless treatment of barium slag with co-production of barium carbonate, characterized in that, It includes the following steps: S1: Crush and screen the barium slag to obtain barium slag powder with a particle size ≤ 5 mm; S2: Mix the barium slag powder with a hydrochloric acid solution, heat and stir for reaction for 1 - 2 h, perform plate and frame pressure filtration to obtain a pressure filtrate and a pressure filter residue; the filter residue is subjected to high-temperature calcination treatment until constant weight to obtain a harmless residue; S3: Add a precipitant to the pressure filtrate to adjust the pH value to 8 - 10, add a flocculant, perform natural sedimentation treatment for 1 - 2 h, and filter to obtain a filter residue and a filtrate; the filtrate is sent to a wastewater treatment system for wastewater treatment; S4: Wash the filter residue with water until the Cl - content is less than 0.01% to obtain washing wastewater and filter cake; dry the filter cake to constant weight to obtain barium carbonate; recycle the washing wastewater to wash and treat the filter residue.

2. The method for harmless treatment of barium slag with co-production of barium carbonate according to claim 1, characterized in that, The mass percentage concentration of the hydrochloric acid solution is 5 - 10%, and the barium slag powder and the hydrochloric acid solution are in a solid-liquid mass ratio of 1:3 - 1:5; the heating and stirring reaction is carried out with a stirring speed of 300 - 400 r / min and heated to a temperature of 50 - 70 °C for reaction.

3. The method for harmless treatment of barium slag and co-production of barium carbonate according to claim 1 or 2, characterized in that The mass percentage concentration of the hydrochloric acid solution is 8%, and the barium slag powder and the hydrochloric acid solution are in a solid-liquid mass ratio of 1:5; the heating and stirring reaction is carried out with a stirring speed of 300 - 400 r / min and heated to a temperature of 60 °C for reaction.

4. The method for harmless treatment of barium slag with co-production of barium carbonate according to claim 1, characterized in that, The high-temperature calcination temperature is 200 - 400 °C.

5. The method for harmless treatment of barium slag with co-production of barium carbonate according to claim 1, characterized in that, The precipitant is one or two of sodium carbonate or sodium bicarbonate; and the flocculant is polyaluminum oxide accounting for 0.1% of the mass of the pressure filtrate.

6. The method for harmless treatment of barium slag and co-production of barium carbonate according to claim 1, characterized in that, The drying of the filter cake is at a temperature of 100 - 120 °C.

7. An apparatus for harmless treatment of barium slag with co-production of barium carbonate, characterized in that, It includes a raw slag bin (1), a crusher (2), a filter (9) and a reaction kettle (4), and there is a belt conveyor A (13) between the raw slag bin (1) and the crusher (2); a vibrating screen (3) is provided at the bottom of the crusher (2), and there is a belt conveyor B (15) between the bottom of the vibrating screen (3) and the reaction kettle (4); a hydrochloric acid solution tank is connected to the reaction kettle (4) through a pipeline; A plate and frame filter press (5) is provided at the bottom of the reaction kettle (4), the bottom of the plate and frame filter press (5) is connected to a flocculation and precipitation tank (8) through a pipeline, and the plate and frame filter press (5) is connected to a calciner (6) through a belt conveyor D; the calciner (6) is connected to a harmless slag bin (7) through a belt conveyor E; the bottom of the flocculation and precipitation tank (8) is connected to the filter (9), the filter (9) is connected to a washing tank (10) through a belt conveyor F, the washing tank (10) is connected to a drying tower (11) through a belt conveyor G, and the drying tower (11) is connected to a barium carbonate bin (12) through a belt conveyor H.

8. The device for harmless treatment of barium slag and co-production of barium carbonate according to claim 7, characterized in that, A washing wastewater tank is provided at the bottom of the washing tank (10), and there is a circulation pipe between the washing wastewater tank and the washing tank (10); and the bottom of the filter (9) is connected to a wastewater treatment system through a pipeline.

9. The device for harmless treatment of barium slag with co-production of barium carbonate according to claim 7, wherein There is a hot gas circulation and utilization pipeline between the calciner (6) and the drying tower (11).

10. The device for harmless treatment of barium slag and co-production of barium carbonate according to claim 7, wherein, The crusher (2) is a jaw crusher, and the aperture of the screen holes of the vibrating screen (3) is 5 mm.

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