Method for continuously removing fluorine and chlorine from fluorine-containing chlorine-containing zinc oxide waste by differential contact countercurrent washing tower

Abstract

The present invention discloses a method for continuously removing fluorine and chlorine from fluorine-containing chlorine-containing zinc oxide waste by using a differential contact countercurrent washing tower, comprising the following steps: adding fluorine-containing chlorine-containing zinc oxide waste from the top of a first-level washing and stirring tower for solid-liquid differential contact countercurrent washing, sending it to a first-level centrifugal separator, treating the separated liquid phase separately, and sending the solid phase to a second-level washing and stirring tower; and so on, sending it to a pulping tank after multiple stages of differential contact countercurrent washing; adjusting it to neutral to slightly acidic, and obtaining the product after pulping treatment. The present invention is based on continuous automated operation technology for processing, and can effectively improve production efficiency and product quality through the efficient differential mass transfer method of a countercurrent washing tower with a specific structure.

Description

Technical Field

[0001] The invention belongs to the technical field of zinc hydrometallurgy, and in particular relates to a method for removing fluorine and chlorine from zinc oxide by hydroalkali elution. Background Art

[0002] Zinc oxide waste is widely used in the application fields of rotary kiln volatilization of lead and zinc smelters, fuming furnace volatilization dust, multi-hearth furnace dust for defluorination and chlorination treatment of zinc oxide powder, converter dust, blast furnace gas ash, hot-dip galvanizing slag and waste zinc-manganese battery recycling. Zinc oxide waste generally contains valuable metals such as zinc, lead, indium and germanium, and has great resource recovery value. Before recycling these valuable metals, it is necessary to remove fluorine and chlorine from zinc oxide waste to protect smelting equipment and ensure the quality of smelted metal.

[0003] Domestic and foreign patents focus on the research and development of fluorine and chlorine removal from zinc oxide waste by roasting pyrolysis, and a small number of methods for fluorine and chlorine removal by alkali elution of zinc oxide have been studied. However, the degree of fluorine and chlorine removal of these existing methods is limited, and most of them are discontinuous operations, which affects the process efficiency and convenience of operation. Chinese patent application No. CN116242132A discloses a zinc oxide defluorination and chlorine system and method, which uses a rotary kiln to discharge fluorine and chlorine-containing flue gas at high temperature to achieve the purpose of removing fluorine and chlorine from zinc oxide. Chinese patent document No. CN113122734B discloses a smelting method for defluorination and chlorine of secondary zinc oxide, firstly, secondary zinc oxide is sent into a rotary kiln for roasting, and the roasting flue gas is collected and sprayed, and then the valuable metals in the filter mud are recovered. Chinese patent document No. CN112538568B discloses a method for removing fluorine and chlorine from zinc oxide powder by low-temperature roasting combined with water washing, which is roasted with carbonate ingredients, stirred and leached, and then filtered to achieve the purpose of defluorination and chlorine. This patent adopts low-temperature roasting combined with water washing, which has a complex process and high equipment investment. After roasting to high temperature, the energy consumption of water washing is high. Chinese patent document CN105483362B discloses a process and device for multi-stage countercurrent continuous rinsing and dechlorination of zinc oxide smoke. A three-stage countercurrent filter press is used to achieve solid-liquid separation, but it fails to achieve completely continuous operation; each stage uses a single rinsing tank, and the dechlorination slag produced in the last stage has a chlorine content of 0.3%~2%. The degree of chlorine removal is low and cannot meet the requirement of a chlorine content of less than 0.05%. Chinese patent document CN102091524B discloses a method for alkaline washing and dechlorination treatment of zinc oxide smoke, which uses a thickener and a filter press for thickening and solid-liquid separation, and also fails to achieve continuous deep defluorination and chlorination.

[0004] The above existing methods all have many problems such as non-continuous process, difficulty in automation, harsh working environment for workers, complex operation, low degree of defluorination and chlorination, etc., which are difficult to meet the requirements of economic, environmentally friendly and efficient resource utilization of zinc oxide waste. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology and provide a method for continuously removing fluorine and chlorine from fluorine-containing zinc oxide waste using a differential contact countercurrent washing tower with high defluorination and chlorination degree and continuous automation.

[0006] In order to solve the above technical problems, the technical solution proposed in the present invention is a method for continuously removing fluorine and chlorine from fluorine-containing zinc oxide waste using a differential contact countercurrent washing tower, comprising the following steps:

[0007] Step a: adding fluorine-containing zinc oxychloride waste from the top of a primary washing and stirring tower, performing solid-liquid differential contact countercurrent washing on the fluorine-containing zinc oxychloride waste in the primary washing and stirring tower, sending the washed solid phase to a primary centrifugal separator by a washing delivery pump for solid-liquid separation, treating the washed liquid phase and the liquid phase of the primary centrifugal separator separately, and sending the primary solid phase obtained by the primary centrifugal separator to a secondary washing and stirring tower;

[0008] Step b: the primary solid phase in step a is added from the top of the secondary washing and stirring tower, and the primary solid phase is subjected to solid-liquid differential contact countercurrent washing in the secondary washing and stirring tower. The washed solid phase is sent to the secondary centrifugal separator by a washing delivery pump for solid-liquid separation. The washed liquid phase and the liquid phase of the secondary centrifugal separator are processed separately, and the secondary solid phase obtained by the secondary centrifugal separator is sent to subsequent washing and stirring towers of more stages or to a slurry tank;

[0009] After being sent to subsequent washing and stirring towers of more stages for countercurrent washing in the same manner as the above-mentioned first-stage or second-stage washing and stirring towers, it is finally sent to the pulping tank;

[0010] Step c: The pH value of the solid phase sent to the slurry tank in the above step is adjusted to neutral to slightly acidic, mixed and slurried, and the product is obtained after the slurry treatment.

[0011] The above technical solution of the present invention uses a differential mass transfer unit to treat fluorine-containing chlorine-containing zinc oxide waste, and the application in a countercurrent washing tower has a very strong mass transfer effect, achieving an excellent effect of removing fluorine and chlorine. Due to the high degree of fluorine and chlorine removal, it can be directly used in the electrolytic zinc deposition system without additional treatment, which greatly simplifies the operation and saves resources and energy consumption.

[0012] In the above technical scheme, preferably, the fluorine-containing zinc oxychloride waste is a mixture of one or more of the volatilization dust from the rotary kiln of the lead-zinc smelter, the volatilization dust from the fuming furnace, the multi-hearth furnace dust from the defluorination and chlorination treatment of zinc oxide powder, and the waste generated by the recycling of waste zinc-manganese batteries. The fluorine-containing zinc oxychloride waste has a zinc content of 30% to 60%, a fluorine content of more than 0.1%, and a chlorine content of 0.1% to 0.80%.

[0013] In the above technical solution, preferably, the liquid phase used for washing in the countercurrent washing process is pure water or alkaline solution. When the fluorine and chlorine content in the treated waste is low, pure water can be used. When the fluorine and chlorine content is high, sodium carbonate can be preferably added to wash in the form of alkaline solution. The alkaline solution is prepared by using the pure water and sodium carbonate to prepare a sodium carbonate solution with a mass fraction of 20% to 32%, and the pure water is pure water with a conductivity of <12μS / cm; the volume ratio of the liquid phase to the solid phase in the countercurrent washing process is 1.5 to 8, and the washing temperature is 50°C to 90°C.

[0014] In the above technical scheme, preferably, in step c, the pH value adjustment is carried out with water or acid, and the volume ratio of water or acid to the solid phase fed into the slurry tank is 1 to 2; the acid is a sulfuric acid solution with a mass fraction of 5 to 30% prepared by pure water and sulfuric acid, and the pure water is pure water with a conductivity of <12μS / cm.

[0015] In the above technical solution, preferably, in each level of the washing and stirring tower, the liquid phase is fed from the lower part of the washing and stirring tower in a dispersed spray manner, and the solid phase is fed from the upper inclined tube of the washing and stirring tower, and the solid phase and the liquid phase in the tower are radially dispersed at high speed through the multi-level stirring device in the tower, and axial up and down countercurrent washing is performed at the same time. By setting a multi-level stirring device and combining countercurrent washing, the solid phase and the liquid phase can perform a countercurrent mass transfer process in multiple regions, thereby significantly improving the removal effect of fluorine and chlorine in zinc oxide.

[0016] Furthermore, the height-to-diameter ratio of the washing and stirring tower is 4-10; the dispersed injection feeding is dispersedly injected through a distribution pipe extending into the washing and stirring tower, the spray hole of the distribution pipe is opened toward the bottom of the washing and stirring tower, and an inverted cone-shaped liquid collection cavity is provided at the bottom of the tower; the liquid phase is sprayed toward the bottom of the washing and stirring tower and then countercurrently enters the stirring area of ​​the multi-level stirring device. In this way, the mass transfer stroke of the liquid phase in the washing and stirring tower along the radial and axial directions can be greatly extended, and the removal effect of fluorine and chlorine in zinc oxide can be further improved.

[0017] Furthermore, a clarification chamber is provided at the top of the washing and stirring tower, and the height of the clarification chamber is 500-1000 mm. The liquid phase countercurrently flows upward through the clarification chamber, and the solid phase enters below the clarification chamber through an inclined tube and obliquely toward the stirring shaft of the multi-level stirring device. Through the stirring of the multi-level stirring device, the solid phase and the liquid phase countercurrently flow axially and disperse at high speed radially, and the solid phase effectively avoids the clarification chamber, preventing the liquid phase from entraining the solid phase into the upper-level stirring tower, thereby improving the processing efficiency and avoiding repeated removal of materials.

[0018] More preferably, the multi-stage stirring device includes 3 to 10 stirring mechanisms arranged from top to bottom in the tower (generally, three stages are preferred to achieve the effect), the stirring mechanism adopts one or more of paddle type, anchor type, frame type, and turbine type, and the multi-stage stirring device divides the stirring area of ​​the washing stirring tower from top to bottom into a plurality of differential unit mass transfer zones, and the liquid phase and the solid phase are contacted and transferred in a plurality of differential unit mass transfer zones in a countercurrent manner. More preferably, two adjacent differential unit mass transfer zones are separated by a grid or a partition, and an inclined grid is arranged under at least part of the grid or the partition, and the bottom edge of the inclined grid is located above the stirring paddle of the lower stirring mechanism; the uppermost stirring mechanism is a paddle type, a turbine type, or a combination of the two, and the stirring speed is 200 to 300 r / min, and the lowermost stirring mechanism is an anchor type, a frame type, or a combination of the two, and the stirring speed is 80 to 200 r / min; the stirring temperature during the stirring process is preferably controlled at 50 to 90°C. The inclined grid can gather the solid phase to the stirring center. After the solid phase is re-gathered, it is highly dispersed radially through the stirring mechanism to achieve the purpose of solid phase redistribution, which is beneficial to liquid-solid mass transfer.

[0019] In the above technical scheme, preferably, the liquid phase of the first-stage washing and stirring tower mainly comes from the liquid phase collected by the second-stage washing and stirring tower and the second-stage centrifugal separator, and the liquid phase of the second-stage washing and stirring tower mainly comes from the liquid phase collected by the third-stage washing and stirring tower and the third-stage centrifugal separator, and so on. The liquid phase of the current-stage washing and stirring tower mainly comes from the liquid phase collected by the next-stage washing and stirring tower and the next-stage centrifugal separator, and the liquid phase used for washing in the last-stage washing and stirring tower is pure water or alkaline solution injected from the outside of the system.

[0020] In the above technical scheme, preferably, the centrifugal separators at each level are selected from one of the vertical centrifuges, horizontal screw centrifuges or drum centrifuges, with a separation factor of 1000-2000, and the moisture content of the separated solid phase material is ≤30%, and the solid content of the liquid phase is ≤2%. Due to the use of a differential mass transfer unit in the early stage, the solid phase particles output by the washing tower are uniform, and the phase distribution is also uniform, achieving a good effect of deep removal of fluorine and chlorine. By controlling the washing temperature in the washing tower, the output solid phase can be well separated in the centrifugal separator, thereby achieving fully continuous and automated operation, greatly improving production efficiency.

[0021] In the above technical solution, preferably, in step b, the secondary solid phase obtained by the secondary centrifugal separator is directly fed into the slurry tank. Since the technical solution of the present invention has a good defluorination and chlorination effect, more stages of countercurrent washing towers are not required in most cases, and only two-stage countercurrent washing can achieve the effect, which is more conducive to reducing equipment investment and simplifying the process.

[0022] In the above technical solution, preferably, a stirring mechanism is provided in the slurry tank, and the stirring mechanism is one of a paddle type, an anchor type, a frame type, and a turbine type.

[0023] In the above technical scheme, preferably, the method further comprises the step of reducing the fluorine content of the product obtained in step c to less than 0.02% and the chlorine content to less than 0.05%, and delivering the product to an electrolytic zinc system through a slurry delivery pump, and the post-electrolytic liquid of the electrolytic zinc system is used to prepare acid solution and return it to the slurry tank.

[0024] Compared with the prior art, the advantages of the present invention are:

[0025] 1. By combining the differential mass transfer unit of the present invention, the zinc oxide waste with fluorine and chlorine contents of more than 0.1% (even as high as more than 0.8%) can be removed to less than 0.02% fluorine and less than 0.05% chlorine. Due to the high degree of fluorine and chlorine removal, it can be directly sent to the subsequent electrolytic zinc system process.

[0026] 2. The present invention adopts a multi-stage countercurrent washing tower combined with differential mass transfer technology. The solid phase is added from the top of the tower, and the liquid phase is added from the middle and lower part. The axial countercurrent in the tower and the radial high-speed dispersion stirring strengthen the liquid-solid interface mass transfer, which is beneficial to the deep washing and removal of fluorine and chlorine.

[0027] 3. The present invention is based on continuous automated operation technology for processing. Through the efficient differential mass transfer method of the countercurrent washing tower with a specific structure, it can effectively improve production efficiency, improve product quality, and promote the development of zinc hydrometallurgy industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 The system structure and process flow diagram of the method for continuously removing fluorine and chlorine from fluorine-containing zinc oxide waste in an embodiment of the present invention.

[0030] Figure 2 Schematic diagram of the differential mass transfer unit in an embodiment of the present invention.

[0031] Figure 3 Schematic diagram of the internal structure of the washing and stirring tower in an embodiment of the present invention.

[0032] Legend

[0033] Among them, 1-a first-level washing and stirring tower, 2-a first-level washing and conveying pump, 3-a first-level centrifugal separator, 4-a second-level washing and stirring tower, 5-a second-level washing and conveying pump, 6-a second-level centrifugal separator, 7-a third-level washing and stirring tower, 8-a third-level washing and conveying pump, 9-a third-level centrifugal separator, 10-a slurry tank, 11-a slurry conveying pump, 12-an inclined pipe, 13-a distribution pipe, 14-a liquid confluence chamber, 15-a clarifying chamber, 16-a differential unit mass transfer zone, 17-a partition, 18-an inclined grid, 19-an uppermost stirring mechanism, 20-a lowermost stirring mechanism, 21-a fluorine-containing chlorinated zinc oxide waste, 22-a discharge liquid, 23-pure water or alkali solution, 24-zinc oxide slurry. DETAILED DESCRIPTION

[0034] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments.

[0035] It should be noted that when an element is described as being "fixed, fixed, connected or connected to" another element, it can be directly fixed, fixed, connected or connected to the other element, or it can be indirectly fixed, fixed, connected or connected to the other element through other intermediate connectors.

[0036] Unless otherwise defined, all the professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0037] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0038] Embodiment 1:

[0039] In this embodiment, the method of the present invention is used to treat 2.5t / h of fluorine-containing zinc oxychloride material, whose mass composition is 62.50% zinc oxide (50.15% zinc), 6.1% iron, 29.32% sulfur, 0.02% copper, 0.60% lead, 0.07% cadmium, 0.09% arsenic, 0.23% sodium fluoride (0.1%), 0.82% sodium chloride (0.5%), 0.05% germanium and 0.09% antimony, and the rest is impurities. The fluorine-containing zinc oxychloride waste is a mixture of the volatilization of rotary kilns and fuming furnaces in lead-zinc smelters, the multi-hearth furnace smoke for defluorination and chlorination treatment of zinc oxide powder, and the waste generated by the recovery of waste zinc-manganese batteries.

[0040] like Figure 1As shown, the method for continuously removing fluorine and chlorine from fluorine-containing zinc oxide waste using a differential contact countercurrent washing tower adopted in this embodiment specifically comprises the following steps:

[0041] Step a: adding the fluorine-containing zinc oxychloride waste 21 of the present embodiment from the top of the primary washing and stirring tower 1, performing solid-liquid differential contact countercurrent washing on the fluorine-containing zinc oxychloride waste in the primary washing and stirring tower 1, the temperature is 56° C., the washed solid phase is sent to the primary centrifugal separator 3 by the primary washing delivery pump 2 for solid-liquid separation, the washed liquid phase and the liquid phase of the primary centrifugal separator 3 are combined and then the discharged liquid 22 is output for separate treatment, and the primary solid phase (moisture content 26.7%) obtained by the primary centrifugal separator 3 is sent to the secondary washing and stirring tower 4;

[0042] Step b: the primary solid phase in step a is added from the top of the secondary washing and stirring tower 4, and the primary solid phase is subjected to solid-liquid differential contact countercurrent washing in the secondary washing and stirring tower 4 at a temperature of 59° C. The washed solid phase is sent to the secondary centrifugal separator 6 by the secondary washing delivery pump 5 for solid-liquid separation, and the washed liquid phase and the liquid phase of the secondary centrifugal separator 6 are separately sent to the primary washing and stirring tower 1 for use as liquid phases, and the secondary solid phase (moisture content 29.7%) obtained by the secondary centrifugal separator 6 is sent to the subsequent tertiary washing and stirring tower 7;

[0043] The secondary solid phase is added from the top of the tertiary washing and stirring tower 7, and the secondary solid phase is subjected to solid-liquid differential contact countercurrent washing in the tertiary washing and stirring tower 7, and the temperature is 60°C. The washed solid phase is sent to the tertiary centrifugal separator 9 by the tertiary washing delivery pump 8 for solid-liquid separation, and the washed liquid phase and the liquid phase of the tertiary centrifugal separator 9 are separately sent to the secondary washing and stirring tower 4 for use as liquid phases. The tertiary solid phase (3.4 t / h solid phase, moisture content 28.5%, fluorine content 0.005%, chlorine content 0.03%) obtained by the tertiary centrifugal separator 9 is finally sent to the slurry tank 10;

[0044] Step c: the pH value of the solid phase fed into the slurry tank 10 in the above step is adjusted to 6.3, and the pH value adjustment is carried out with water or acid solution, and the volume ratio of water or acid solution to the solid phase fed into the slurry tank is 1.04; the acid solution is a sulfuric acid solution with a mass fraction of 10% prepared by pure water and sulfuric acid, and the pure water is pure water with a conductivity of <12μS / cm, and the mixture is mixed for slurry treatment. A stirring mechanism is provided in the slurry tank, and the stirring mechanism is a paddle type. After the slurry treatment, the product is obtained, and the product is fed into an electrolytic zinc system through a slurry delivery pump 11. The liquid after electrolysis of the electrolytic zinc system is used to prepare the acid solution and return to the slurry tank.

[0045] In this embodiment, the liquid phase of the first-stage washing and stirring tower mainly comes from the liquid phase collected by the second-stage washing and stirring tower and the second-stage centrifugal separator, and the liquid phase of the second-stage washing and stirring tower mainly comes from the liquid phase collected by the third-stage washing and stirring tower and the third-stage centrifugal separator. The liquid phase used for washing in the third-stage washing and stirring tower is pure water or alkali solution 23 injected from the outside of the system (adjusted according to the situation of online real-time monitoring). When the fluorine and chlorine content in the treated waste is low, pure water can be used. When the fluorine and chlorine content is high, sodium carbonate can be added to wash in the form of alkali solution. The alkali solution is prepared by using the pure water and sodium carbonate to prepare a sodium carbonate solution with a mass fraction of 23%, and the pure water is pure water with a conductivity of <12μS / cm; the volume ratio of the liquid phase to the solid phase during the countercurrent washing process is 2.6, and the washing temperature is 50℃~60℃, which increases step by step.

[0046] The above technical solution of the present invention uses a differential mass transfer unit to treat fluorine-containing chlorine-containing zinc oxide waste, and the application in a countercurrent washing tower has a very strong mass transfer effect, achieving an excellent effect of removing fluorine and chlorine. Due to the high degree of fluorine and chlorine removal, the subsequent output zinc oxide slurry 24 can be directly used in the electrolytic zinc deposition system without additional treatment, which greatly simplifies the operation and saves resources and energy consumption.

[0047] In this embodiment, Figure 2 , Figure 3 As shown, in each level of the washing and stirring tower, the washing and stirring tower has a diameter of 1.4m, a height of 6m, a volume of about 9.2m³, and a height-to-diameter ratio of about 4.3 (preferably, the height is generally not less than 6m, and the volume is generally not less than 9m³). The liquid phase is fed from the distribution pipe 13 at the bottom of the washing and stirring tower, and the solid phase is fed from the inclined pipe 12 at the top of the washing and stirring tower. The multi-stage stirring device in the tower is used to disperse the solid and liquid phases in the tower at a high speed, and simultaneously, the up-and-down countercurrent washing is performed. Figure 2 The basic principle of countercurrent mass transfer of fluorine and chlorine impurities between different phases is shown, that is, the mass transfer of fluorine and chlorine impurities is driven by the chemical potential gradient. During the mass transfer process, the substance moves from the high chemical potential (high concentration) area to the low chemical potential (low concentration) area. Through the multiple differential unit mass transfer zones created in the washing tower by the present invention, the fluorine and chlorine impurities can break the interface resistance and gradually transfer from the solid phase to the liquid phase, thereby achieving a better defluorination and chlorination effect.

[0048] The multi-stage stirring device of this embodiment is as follows Figure 3As shown, there are three levels of stirring mechanisms arranged from top to bottom in the tower. The multi-level stirring device divides the stirring area of ​​the washing and stirring tower from top to bottom into multiple differential unit mass transfer zones 16. The liquid phase and the solid phase are contacted and transferred in countercurrent step by step in multiple differential unit mass transfer zones 16. Two adjacent differential unit mass transfer zones 16 are separated by a partition 17. An inclined grid 18 is arranged under some of the partitions 17. The bottom edge of the inclined grid 18 is located above the stirring paddle of the lower stirring mechanism. The uppermost stirring mechanism 19 and the middle stirring mechanism are both paddle-type with a stirring speed of 200r / min. The lowermost stirring mechanism 20 is anchor-type with a stirring speed of 100r / min. An inverted conical liquid collection chamber 14 is arranged at the bottom of the tower, and a clarification chamber 15 is arranged at the top of the tower with a height of 600mm. The stirring temperature during the stirring process is the above-mentioned washing temperature.

[0049] In this embodiment, the centrifugal separators at all levels are selected as vertical centrifuges with a separation factor of 1200. The moisture content of the separated solid phase material is 26.7-29.7%, and the solid content of the liquid phase is 0.2%. Due to the use of the differential mass transfer unit area 16 in the early stage, the solid phase particles output by the washing tower are uniform, and the phase distribution is also uniform, achieving a good effect of deep removal of fluorine and chlorine. By controlling the washing temperature in the washing tower, the output solid phase can be well separated in the centrifugal separator, thereby achieving fully continuous and automated operation, greatly improving production efficiency. Compared with traditional methods such as the intermittent method of the comparative example, the 1h feeding time of the stirring tank and the 3h peeling and cleaning time of the filter press in each 8h shift are all auxiliary time, which is non-production time. The present invention is fully continuous and automated, there is no auxiliary time, and the production time is correspondingly increased by 1 times. Therefore, the labor operation efficiency of the intermittent method is generally only 50% of the present invention.

[0050] Embodiment 2:

[0051] In this embodiment, the method of the present invention is used to treat 2.5 t / h of fluorine-containing zinc oxychloride material, whose mass composition is 58.40% zinc oxide (46.86% zinc), 8.48% iron, 31.10% sulfur, 0.02% copper, 0.50% lead, 0.06% cadmium, 0.10% arsenic, 0.24% sodium fluoride (0.11%), 0.94% sodium chloride (0.57%), 0.06% germanium and 0.10% antimony. The fluorine-containing zinc oxychloride waste is a mixture of volatile dust from rotary kilns and fuming furnaces in lead-zinc smelters, volatile dust from multi-hearth furnaces for defluorination and chlorination treatment of zinc oxide powder, and waste materials generated by recycling of waste zinc-manganese batteries.

[0052] The method for continuously removing fluorine and chlorine from fluorine-containing chlorine-containing zinc oxide waste by using a differential contact countercurrent washing tower adopted in this embodiment (see Figure 1 ,only Figure 1 The three-stage washing and stirring tower and the three-stage centrifugal separator are reduced in the process), which specifically includes the following steps:

[0053] Step a: adding the fluorine-containing zinc oxychloride waste of the present embodiment from the top of the primary washing and stirring tower 1, performing solid-liquid differential contact countercurrent washing on the fluorine-containing zinc oxychloride waste in the primary washing and stirring tower 1, the temperature is 66° C., the washed solid phase is sent to the primary centrifugal separator 3 by the primary washing delivery pump 2 for solid-liquid separation, the washed liquid phase and the liquid phase of the primary centrifugal separator 3 are processed separately, and the primary solid phase (moisture content 26.6%) obtained by the primary centrifugal separator 3 is sent to the secondary washing and stirring tower 4;

[0054] Step b: the primary solid phase in step a is added from the top of the secondary washing and stirring tower 4, and the primary solid phase is subjected to solid-liquid differential contact countercurrent washing in the secondary washing and stirring tower 4 at a temperature of 71°C. The washed solid phase is sent to the secondary centrifugal separator 6 by the secondary washing delivery pump 5 for solid-liquid separation, and the washed liquid phase and the liquid phase of the secondary centrifugal separator 6 are separately sent to the primary washing and stirring tower 1 for use as liquid phases. The secondary solid phase (3.5 t / h solid phase, moisture content 29.6%, fluorine content 0.015%, chlorine content 0.036%) obtained by the secondary centrifugal separator 6 is sent to the subsequent slurry tank 10;

[0055] Step c: the pH value of the solid phase fed into the slurry tank 10 in the above step is adjusted to 6.3, and the pH value adjustment is carried out with water or acid solution, and the volume ratio of water or acid solution to the solid phase fed into the slurry tank is 1.04; the acid solution is a 10% sulfuric acid solution prepared by pure water and sulfuric acid, and the pure water is pure water with a conductivity of <12μS / cm, and the mixture is mixed for slurry treatment. A stirring mechanism is provided in the slurry tank, and the stirring mechanism is a paddle type. After the slurry treatment, the product is obtained, and the product is fed into an electrolytic zinc system through a slurry delivery pump. The liquid after electrolytic zinc deposition in the electrolytic zinc deposition system is used to prepare the acid solution and return to the slurry tank.

[0056] In this embodiment, the liquid phase of the primary washing and stirring tower mainly comes from the liquid phase collected by the secondary washing and stirring tower and the secondary centrifugal separator. The liquid phase of the secondary washing and stirring tower is pure water or alkali solution injected from the outside of the system (adjusted according to the situation of online real-time monitoring). When the fluorine and chlorine content in the treated waste is low, pure water can be used. When the fluorine and chlorine content is high, sodium carbonate can be added to wash in the form of alkali solution. The alkali solution is prepared by using the pure water and sodium carbonate to prepare a sodium carbonate solution with a mass fraction of 30%, and the pure water is pure water with a conductivity of <12μS / cm; the volume ratio of the liquid phase to the solid phase in the countercurrent washing process is 2.6, and the washing temperature is 60℃~75℃, which increases step by step.

[0057] In this embodiment, the structure of the washing and stirring towers at each stage is the same as that of Embodiment 1. The centrifugal separators at each stage are vertical centrifuges with a separation factor of 1200. The moisture content of the separated solid phase material is 26.6-29.6%, and the solid content of the liquid phase is 0.2%.

[0058] In this embodiment, if the solid phase of each stage of the washing and stirring tower is not fed through an inclined tube but directly vertically downward, the effect of axial countercurrent and radial high-speed dispersion of the solid and liquid phases will be relatively inferior. At this time, the centrifugal separators at each stage have a moisture content of 28.2~31.5% for the separated solid phase materials and a solid content of 0.7% for the liquid phase.

[0059] Embodiment 3:

[0060] In this embodiment, the method of the present invention is used to treat 2.5 t / h of fluorine-containing zinc oxychloride material, whose mass composition is 71.50% zinc oxide (57.38% zinc), 9.74% iron, 3.01% sulfur, 13.46% lead, 0.05% cadmium, 0.50% arsenic, 0.46% sodium fluoride (0.21%), 1.07% sodium chloride (0.65%), 0.01% germanium and 0.20% antimony. The fluorine-containing zinc oxychloride waste is a mixture of the volatilization of rotary kilns and fuming furnaces in lead-zinc smelters, the multi-hearth furnace smoke for defluorination and chlorination treatment of zinc oxide powder, and the waste generated by the recovery of waste zinc-manganese batteries.

[0061] The method for continuously removing fluorine and chlorine from fluorine-containing zinc oxide waste using a differential contact countercurrent washing tower adopted in this embodiment specifically comprises the following steps:

[0062] Step a: adding the fluorine-containing zinc oxychloride waste of the present embodiment from the top of the primary washing and stirring tower 1, performing solid-liquid differential contact countercurrent washing on the fluorine-containing zinc oxychloride waste in the primary washing and stirring tower 1, the temperature is 76° C., the washed solid phase is sent to the primary centrifugal separator 3 by the primary washing delivery pump 2 for solid-liquid separation, the washed liquid phase and the liquid phase of the primary centrifugal separator 3 are processed separately, and the primary solid phase (moisture content 24.5%) obtained by the primary centrifugal separator 3 is sent to the secondary washing and stirring tower 4;

[0063] Step b: the primary solid phase in step a is added from the top of the secondary washing and stirring tower 4, and the primary solid phase is subjected to solid-liquid differential contact countercurrent washing in the secondary washing and stirring tower 4 at a temperature of 80° C. The washed solid phase is sent to the secondary centrifugal separator 6 by the secondary washing delivery pump 5 for solid-liquid separation, and the washed liquid phase and the liquid phase of the secondary centrifugal separator 6 are separately sent to the primary washing and stirring tower 1 for use as liquid phases, and the secondary solid phase (moisture content 26.0%) obtained by the secondary centrifugal separator 6 is sent to the subsequent tertiary washing and stirring tower 7;

[0064] The secondary solid phase is added from the top of the tertiary washing and stirring tower 7, and the secondary solid phase is subjected to solid-liquid differential contact countercurrent washing in the tertiary washing and stirring tower 7, and the temperature is 81°C. The washed solid phase is sent to the tertiary centrifugal separator 9 by the tertiary washing delivery pump 8 for solid-liquid separation, and the washed liquid phase and the liquid phase of the tertiary centrifugal separator 9 are separately sent to the secondary washing and stirring tower 4 for use as liquid phases. The tertiary solid phase (3.3 t / h solid phase, moisture content 26.2%, fluorine content 0.002%, chlorine content 0.013%) obtained by the tertiary centrifugal separator 9 is finally sent to the slurry tank 10;

[0065] Step c: the pH value of the solid phase fed into the slurry tank 10 in the above step is adjusted to 6.3, and the pH value adjustment is carried out with water or acid solution, and the volume ratio of water or acid solution to the solid phase fed into the slurry tank is 1.04; the acid solution is a 10% sulfuric acid solution prepared by pure water and sulfuric acid, and the pure water is pure water with a conductivity of <12μS / cm, and the mixture is mixed for slurry treatment. A stirring mechanism is provided in the slurry tank, and the stirring mechanism is a paddle type. After the slurry treatment, the product is obtained, and the product is fed into an electrolytic zinc system through a slurry delivery pump. The liquid after electrolytic zinc deposition in the electrolytic zinc deposition system is used to prepare the acid solution and return to the slurry tank.

[0066] In this embodiment, the liquid phase of the first-stage washing and stirring tower mainly comes from the liquid phase collected by the second-stage washing and stirring tower and the second-stage centrifugal separator, and the liquid phase of the second-stage washing and stirring tower mainly comes from the liquid phase collected by the third-stage washing and stirring tower and the third-stage centrifugal separator. The liquid phase used for washing in the third-stage washing and stirring tower is pure water or alkali solution injected from the outside of the system (adjusted according to the situation of online real-time monitoring). When the fluorine and chlorine content in the treated waste is low, pure water can be used. When the fluorine and chlorine content is high, sodium carbonate can be added to wash in the form of alkali solution. The alkali solution is prepared into a sodium carbonate solution with a mass fraction of 30% using the pure water and sodium carbonate, and the pure water is pure water with a conductivity of <12μS / cm; the volume ratio of the liquid phase to the solid phase during the countercurrent washing process is 4.0, and the washing temperature is 75℃~85℃, which increases step by step. The step-by-step increase in washing temperature combined with the step-by-step increase in liquid phase concentration can better achieve a step-by-step increase in the removal intensity of chlorine and fluorine in the raw materials.

[0067] In this embodiment, the structure of the washing and stirring towers at each stage is the same as that of the embodiment 1. The centrifugal separators at each stage are selected as vertical centrifuges with a separation factor of 1800. The moisture content of the separated solid phase material is 24.5-26.2%, and the solid content of the liquid phase is 0.2%. The three-stage centrifugal separator performs solid-liquid separation to obtain 3.3t / h of solid phase, a moisture content of 26.2%, a fluorine content of 0.002%, and a chlorine content of 0.013%.

[0068] In this embodiment, if the washing and stirring towers at each level are not fed through an inclined tube but directly vertically downward, and no clarification chamber is set on the top, the separation effect will be significantly reduced. At this time, the moisture content of the solid phase separated by the centrifugal separators at each level is 25.8-28.8%, and the solid content of the liquid phase is 0.3%. The three-stage centrifugal separator performs solid-liquid separation to obtain 3.5t / h of solid phase, a moisture content of 27.5%, a fluorine content of 0.005%, and a chlorine content of 0.027%.

[0069] Comparative Example:

[0070] In this comparative example, a conventional method is used to treat 20 t / shift (average 2.5 t / h) of fluorine-containing zinc oxychloride material, 3 shifts per day, 8 hours per shift, and its mass composition is 62.50% zinc oxide (50.15% zinc), 6.1% iron, 29.32% sulfur, 0.02% copper, 0.60% lead, 0.07% cadmium, 0.09% arsenic, 0.23% sodium fluoride (0.1%), 0.82% sodium chloride (0.5%), 0.05% germanium and 0.09% antimony, and the rest is impurities. The fluorine-containing zinc oxychloride waste is a mixture of the volatilization of the rotary kiln of the lead-zinc smelter, the volatilization of the fuming furnace, the multi-hearth furnace smoke dust for defluorination and chlorination treatment of zinc oxide powder, and the waste generated by the recycling of waste zinc-manganese batteries.

[0071] This comparative example adopts a three-stage common countercurrent washing and stirring tank with a height-to-diameter ratio of 1.6 (diameter 4m, height 6.5m, volume about 81.6m³), intermittent feeding and discharging in one shift, and does not contain a differential contact mass transfer unit with continuous feeding and discharging and up and down countercurrent), a three-stage filter press (can only be operated intermittently) to remove fluorine and chlorine from fluorine-containing zinc oxide waste, which specifically includes the following steps:

[0072] Step a: adding the fluorine-containing zinc oxychloride waste of the above comparative example from the top of the primary washing and stirring tank for 1 hour; stirring and washing the fluorine-containing zinc oxychloride waste in the primary washing and stirring tank for 2 hours at a temperature of 56° C.; the washed solid phase is sent to the primary filter press by the primary washing delivery pump for solid-liquid separation, and the filtration time is 2 hours; the liquid phase of the primary filter press is treated separately, and the primary solid phase (moisture content 35.2%) obtained by the primary filter press after 3 hours of peeling and washing process is sent to the secondary washing and stirring tank;

[0073] Step b: the primary solid phase in step a is added from the top of the secondary washing and stirring tank, and the feeding is carried out for 1 hour; the primary solid phase is stirred and washed for 2 hours in the secondary washing and stirring tank, and the temperature is 59°C; the washed solid phase is sent to the secondary filter press by the secondary washing delivery pump for solid-liquid separation, and the filtration time is 2 hours; the liquid phase of the secondary filter press is separately sent to the primary washing and stirring tank for use as the liquid phase, and the secondary solid phase (moisture content 33.8%) obtained by the secondary filter press after 3 hours of peeling and washing process is sent to the subsequent tertiary washing and stirring tank;

[0074] The secondary solid phase is added from the top of the tertiary washing and stirring tank, and the feeding is carried out for 1 hour; the secondary solid phase is stirred and washed for 2 hours in the tertiary washing and stirring tank at a temperature of 60°C; the washed solid phase is sent to the tertiary filter press by the tertiary washing delivery pump for solid-liquid separation, and the filtration time is 2 hours; the liquid phase of the tertiary filter press is separately sent to the secondary washing and stirring tank for use as the liquid phase. The tertiary solid phase (2.5t / h solid phase, moisture content 33.5%, fluorine content 0.04%, chlorine content 0.22%) obtained by the tertiary filter press after 3 hours of stripping and washing process is finally sent to the slurry tank.

[0075] The results of this comparative example show that the defluorinated zinc oxychloride material containing 0.04% fluorine and 0.22% chlorine is obtained by adopting the traditional washing, stirring and filter press process, which cannot meet the requirements of the existing electrolytic zinc system for fluorine and chlorine. The filter press is an intermittent operation device, which requires 3 to 5 people to operate manually and cannot meet the requirements of full continuous automation. The intermittent entry and exit of materials in the traditional washing and stirring tank is cumbersome, and the auxiliary labor time such as stripping and cleaning of the filter press is long. The labor operation rate is low, which is about 50% of the labor operation rate of the present invention, and the investment cost is higher. The material cannot be enclosed in the equipment and pipelines. There is a large amount of acid mist diffused on site and waste residue overflowed to the ground. The labor working conditions are poor, which does not meet the development direction of clean and unmanned intelligent industry.

Claims

1. A method for continuously removing fluorine and chlorine from fluorine-containing zinc oxychloride waste using a differential contact countercurrent washing tower, characterized in that: The steps include: Step a: adding fluorine-containing zinc oxychloride waste from the top of a primary washing and stirring tower, performing solid-liquid differential contact countercurrent washing on the fluorine-containing zinc oxychloride waste in the primary washing and stirring tower, sending the washed solid phase to a primary centrifugal separator by a washing delivery pump for solid-liquid separation, treating the washed liquid phase and the liquid phase of the primary centrifugal separator separately, and sending the primary solid phase obtained by the primary centrifugal separator to a secondary washing and stirring tower; Step b: the primary solid phase in step a is added from the top of the secondary washing and stirring tower, and the primary solid phase is subjected to solid-liquid differential contact countercurrent washing in the secondary washing and stirring tower. The washed solid phase is sent to the secondary centrifugal separator by a washing delivery pump for solid-liquid separation. The washed liquid phase and the liquid phase of the secondary centrifugal separator are processed separately, and the secondary solid phase obtained by the secondary centrifugal separator is sent to subsequent washing and stirring towers of more stages or to a slurry tank; After being sent to subsequent washing and stirring towers of more stages for countercurrent washing in the same manner as the above-mentioned first-stage or second-stage washing and stirring towers, it is finally sent to the pulping tank; In each level of the washing and stirring tower, the liquid phase is fed in a dispersed spraying manner from the lower part of the washing and stirring tower, and the solid phase and liquid phase in the tower are dispersed at a high speed through the multi-level stirring device in the tower, and the vertical countercurrent washing is performed at the same time; Step c: The pH value of the solid phase sent to the slurry tank in the above step is adjusted to neutral to slightly acidic, mixed and slurried, and the product is obtained after the slurry treatment.

2. The method according to claim 1, characterized in that: The fluorine-containing zinc oxychloride waste is a mixture of one or more of the volatilization dust from the rotary kiln of the lead-zinc smelter, the volatilization dust from the fuming furnace, the dust from the multi-hearth furnace for defluorination and chlorination treatment of zinc oxygen powder, and the waste generated by the recycling of waste zinc-manganese batteries. The fluorine-containing zinc oxychloride waste has a zinc content of 30% to 60%, a fluorine content of more than 0.1%, and a chlorine content of 0.1% to 0.80%.

3. The method according to claim 1, characterized in that The liquid phase used for washing in the countercurrent washing process is pure water or alkali solution, the alkali solution is prepared by using pure water and sodium carbonate to prepare a sodium carbonate solution with a mass fraction of 20% to 32%, and the pure water is pure water with a conductivity of <12μS / cm; the volume ratio of the liquid phase to the solid phase in the countercurrent washing process is 1.5 to 8, and the washing temperature is 50°C to 90°C.

4. The method according to claim 1, characterized in that: In step c, the pH value is adjusted using water or acid, and the volume ratio of water or acid to the solid phase fed into the slurry tank is 1-2; the acid is a sulfuric acid solution with a mass fraction of 5-30% prepared by pure water and sulfuric acid, and the pure water is pure water with a conductivity of <12μS / cm.

5. The method according to any one of claims 1 to 4, characterized in that The solid phase is fed from the upper inclined tube of the washing and stirring tower.

6. The method according to claim 5, characterized in that The height-to-diameter ratio of the washing and stirring tower is 4-10; the dispersed injection feeding is dispersedly injected through a distribution pipe extending into the washing and stirring tower, the spray hole of the distribution pipe is opened toward the bottom of the washing and stirring tower, and an inverted cone-shaped liquid collection cavity is provided at the bottom of the tower; The liquid phase is sprayed toward the bottom of the washing and stirring tower and then flows upward in countercurrent into the stirring area of ​​the multi-stage stirring device.

7. The method according to claim 6, characterized in that A clarification chamber is arranged on the top of the washing and stirring tower, and the height of the clarification chamber is 500-1000 mm. The liquid phase passes through the clarification chamber in countercurrent, and the solid phase enters below the clarification chamber through an inclined tube and obliquely toward the stirring shaft of the multi-stage stirring device.

8. The method according to claim 6, characterized in that The multi-stage stirring device includes 3 to 10 stirring mechanisms arranged from top to bottom in the tower, and the stirring mechanism adopts one or more of blade type, anchor type, frame type, and turbine type. The multi-stage stirring device divides the stirring area of ​​the washing and stirring tower from top to bottom into multiple differential unit mass transfer zones, and the liquid phase and the solid phase are contacted and transferred in countercurrent step by step in the multiple differential unit mass transfer zones.

9. The method according to claim 8, characterized in that Two adjacent differential unit mass transfer zones are separated by setting grids or partitions, and an inclined grid is set under at least part of the grids or partitions, and the bottom edge of the inclined grid is located above the stirring paddle of the lower stirring mechanism; the uppermost stirring mechanism is a blade type, a turbine type or a combination of the two, and the stirring speed is 200~300r / min, and the lowermost stirring mechanism is an anchor type, a frame type or a combination of the two, and the stirring speed is 80~200r / min; the stirring temperature during the stirring process is controlled at 50~90℃.

10. The method according to any one of claims 1 to 4, characterized in that The liquid phase of the first-stage washing and stirring tower mainly comes from the liquid phase collected by the second-stage washing and stirring tower and the second-stage centrifugal separator, and the liquid phase of the second-stage washing and stirring tower mainly comes from the liquid phase collected by the third-stage washing and stirring tower and the third-stage centrifugal separator. Similarly, the liquid phase of the current-stage washing and stirring tower mainly comes from the liquid phase collected by the next-stage washing and stirring tower and the next-stage centrifugal separator, and the liquid phase used for washing in the last-stage washing and stirring tower is pure water or alkaline solution injected from the outside of the system.

11. The method according to any one of claims 1 to 4, characterized in that: The centrifugal separators at each level are selected from vertical centrifuges, horizontal screw centrifuges or cylinder centrifuges, with a separation factor of 1000~2000. The moisture content of the separated solid phase material is ≤30%, and the solid content of the liquid phase is ≤2%.

12. The method according to any one of claims 1 to 4, characterized in that In step b, the secondary solid phase obtained by the secondary centrifugal separator is directly sent to the slurry tank.

13. The method according to any one of claims 1 to 4, characterized in that: The method further comprises the step of sending the product obtained in step c to an electrolytic zinc system through a slurry delivery pump, wherein the post-electrolytic liquid of the electrolytic zinc system is used to prepare acid solution and returns to the slurry tank.

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