CN114672664A - Method for removing fluorine and chlorine from zinc electrolyte - Google Patents

Method for removing fluorine and chlorine from zinc electrolyte Download PDF

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CN114672664A
CN114672664A CN202210322037.0A CN202210322037A CN114672664A CN 114672664 A CN114672664 A CN 114672664A CN 202210322037 A CN202210322037 A CN 202210322037A CN 114672664 A CN114672664 A CN 114672664A
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zinc
solution
chlorine
fluorine
ions
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罗远辉
陈松
袁学韬
尚鹤
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GRINM Resources and Environment Technology Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B19/00—Obtaining zinc or zinc oxide
    • C22B19/20—Obtaining zinc otherwise than by distilling
    • C22B19/26—Refining solutions containing zinc values, e.g. obtained by leaching zinc ores
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B19/00—Obtaining zinc or zinc oxide
    • C22B19/20—Obtaining zinc otherwise than by distilling
    • C22B19/22—Obtaining zinc otherwise than by distilling with leaching with acids
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B19/00—Obtaining zinc or zinc oxide
    • C22B19/30—Obtaining zinc or zinc oxide from metallic residues or scraps
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
    • C22B7/02—Working-up flue dust
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
    • C25C1/16—Electrolytic production, recovery or refining of metals by electrolysis of solutions of zinc, cadmium or mercury

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Abstract

The invention provides a method for removing fluorine and chlorine from zinc electrolyte, which comprises the following steps: adding zinc electrolysis waste liquid into a stirring leaching tank, adding zinc-containing smoke dust, taking the zinc electrolysis waste liquid as a zinc leaching agent, and soaking the zinc-containing smoke dust into the zinc electrolysis waste liquid in a steam heating atmosphere to obtain a leaching liquid; filtering the leachate by using a plate press filter, adding a precipitator into the zinc-containing filtrate, heating by using steam to keep the precipitation temperature so as to obtain zinc hydroxide precipitate, and filtering the zinc hydroxide precipitate; repeating the steps until the fluoride ions and the chloride ions in the first solution reach the target concentration to obtain a second solution enriched with the fluoride ions and the chloride ions; sequentially adding a defluorinating agent and a dechlorinating agent into the second solution to remove fluorine and chlorine ions; and cooling and crystallizing the removed solution to obtain sodium sulfate so as to remove sodium ions in the solution. The invention reduces the loss amount of zinc and ensures the removal effect of fluorine and chlorine by a method of firstly depositing zinc and then removing fluorine and chlorine.

Description

Method for removing fluorine and chlorine from zinc electrolyte
Technical Field
The invention relates to the technical field of zinc smelting, in particular to a method for removing fluorine and chlorine from zinc electrolyte.
Background
The zinc concentrate used in the zinc hydrometallurgy generally contains 0.001-1% of fluorine and chlorine, in the leaching process, the fluorine and the chlorine enter a zinc leaching solution and then enter a zinc electrolyte, and zinc electrolysis waste liquid after the fluorine and the chlorine are accumulated returns to the zinc leaching solution or a zinc electrolysis new liquid preparation solution, so that the fluorine and the chlorine are accumulated in the zinc electrolyte, and the concentration is continuously increased. When the fluorine and chlorine concentrations are high to some extent, the zinc electrolysis is adversely affected. Fluorine and chlorine exist in zinc leaching liquid, purifying liquid and electrolyte, which can accelerate corrosion and breakage of impeller and stirring paddle rotating parts of the pump, cause corrosion and dissolution of parts such as pump shell, shaft sleeve and the like contacting with the fluorine and chlorine, cause leakage of the pump, and cause damage to bearings, screws, bases and valves of the pump. Therefore, it is generally required that the content of fluorine ions in the zinc electrolyte is less than 50mg/L and the content of chlorine ions is less than 200 mg/L.
In the prior art, commonly used methods for removing fluorine and chlorine in zinc electrolyte include a chemical precipitation method, an ion exchange method, an extraction method and the like. The chemical precipitation method usually utilizes calcium oxide or calcium salt when removing chloride ions, so that calcium sulfate, zinc fluoride and other precipitates can be generated when removing chloride ions, the obtained gelatinous precipitate is difficult to filter, and a large zinc loss can be caused; anion exchange resin is commonly used in the ion exchange method, but the adsorption capacity of the resin is small, the treatment time is long, and a large amount of wastewater can be generated; the extraction method generally adopts an organic extractant to extract zinc so as to separate the zinc from fluorine and chlorine, but the method needs a large amount of the extractant and has higher treatment cost.
As mentioned above, although there are many methods for removing fluorine and chlorine in zinc electrolyte in the zinc hydrometallurgy industry, most of the above-mentioned processes are to directly remove fluorine and chlorine from zinc solution, and there are many problems that are difficult to solve, mainly the loss of zinc is large, the solution after removing fluorine and chlorine needs to be purified again, the production efficiency of removing fluorine and chlorine is low, and the production cost is high, therefore, the invention adopts the leaching-zinc precipitation method to remove fluorine and chlorine in zinc electrolyte.
Disclosure of Invention
In order to solve the problems, the invention provides a method for removing fluorine and chlorine from a zinc electrolyte. The specific contents are as follows:
the invention provides a method for removing fluorine and chlorine from zinc electrolyte, which comprises the following steps:
step 1, adding zinc electrolysis waste liquid into a stirring leaching tank, adding zinc-containing smoke dust, taking the zinc electrolysis waste liquid as a zinc leaching agent, and soaking the zinc-containing smoke dust into the zinc electrolysis waste liquid in a steam heating atmosphere to obtain a leaching solution; filtering the leachate by using a plate press filter to obtain zinc-containing filtrate;
step 2, adding a precipitator into the zinc-containing filtrate, heating by adopting steam to keep the precipitation temperature so as to obtain zinc hydroxide precipitate, and filtering the zinc hydroxide precipitate to obtain a first solution;
step 3, repeating the steps 1-2 until the fluorine ions and the chloride ions in the first solution reach the target concentration to obtain a second solution enriched with the fluorine ions and the chloride ions;
step 4, sequentially adding a defluorinating agent and a dechlorinating agent into the second solution to remove fluoride ions and chloride ions; wherein the defluorinating agent is calcium oxide, and the dechlorinating agent is copper slag of a zinc smelting system;
and 5, cooling and crystallizing the solution subjected to fluoride ion and chloride ion removal to obtain sodium sulfate so as to remove sodium ions in the solution and obtain a third solution.
Preferably, in the process of introducing the zinc-containing smoke dust into the zinc electrolysis waste liquid in the step 1, stirring for 0.5-5h at a stirring speed of 50-400 rpm.
Preferably, during the precipitation process of the step 2, stirring is carried out for 0.2h-2h at a stirring speed of 60rpm-300 rpm.
Preferably, the fluoride ion content in the third solution is lower than 50mg/L, and the chloride ion content is lower than 200 mg/L.
Preferably, the step 4 specifically includes:
step 4-1, adding a defluorinating agent into the solution enriched with the fluoride ions and the chloride ions in the step 3, and stirring for a first preset time at a steam heating temperature of 60-90 ℃ to remove the fluoride ions; wherein the mass ratio of the addition amount of the defluorinating agent to the fluorinion in the solution is 1.5-3.4: 1;
step 4-2, adding a dechlorinating agent into the solution subjected to the defluorination in the step 4-1, and stirring the solution for a second preset time at the steam heating temperature of 60-90 ℃ to remove chloride ions; wherein the mass ratio of the addition amount of the dechlorinating agent to chloride ions in the solution is 1-3.6: 1.
preferably, the stirring for the first preset time includes stirring at a stirring speed of 60rpm to 300rpm for 0.2 to 1 hour.
Preferably, the stirring for the second preset time includes stirring at a stirring speed of 60rpm to 300rpm for 0.2 to 1 hour.
Preferably, the zinc-containing smoke dust in the step 1 comprises boiling furnace smoke dust, rotary kiln volatile smoke dust or multi-hearth furnace roasting smoke dust.
Preferably, the mass ratio of the zinc-containing smoke dust to the zinc electrolysis waste liquid in the step 1 is 1: 1 to 20; the steam heating temperature is 60-90 ℃, and the pH value of the solution is 3.0-6.0 at the end of leaching.
Preferably, the precipitant in the step 2 comprises at least one of sodium hydroxide and sodium carbonate, the mass fraction of the precipitant is 5 wt% to 40 wt%, and the precipitation temperature is 60 to 95 ℃; the pH of the solution at the end of the precipitation is 6.5-8.0.
Preferably, the target concentration in the step 3 is 1 g/L.
Preferably, the cooling crystallization method in the step 5 comprises cooling by industrial water circulation, and the temperature of the cooling crystallization is 0-15 ℃.
Preferably, the third solution is added to the electrolyte used in the hydrometallurgical zinc process so that the third solution is repeatedly used in the process of obtaining zinc electrolysis waste.
Preferably, the hydroxide precipitate of zinc is used in a hydrometallurgical zinc process to recover zinc.
Compared with the prior art, the invention has the following advantages:
the embodiment of the invention provides a method for removing fluorine and chlorine from zinc electrolyte, which comprises the following steps: adding zinc electrolysis waste liquid into a stirring leaching tank, adding zinc-containing smoke dust, taking the zinc electrolysis waste liquid as a zinc leaching agent, and soaking the zinc-containing smoke dust into the zinc electrolysis waste liquid in a steam heating atmosphere to obtain a leaching liquid; filtering the leachate by using a plate press filter to obtain zinc-containing filtrate; adding a precipitator into the zinc-containing filtrate, heating by adopting steam to keep the precipitation temperature so as to obtain zinc hydroxide precipitate, and filtering the zinc hydroxide precipitate to obtain a first solution; repeating the steps until the fluoride ions and the chloride ions in the first solution reach the target concentration to obtain a second solution enriched with the fluoride ions and the chloride ions; sequentially adding a defluorinating agent and a dechlorinating agent into the second solution to remove fluoride ions and chloride ions; wherein the defluorinating agent is calcium oxide, and the dechlorinating agent is copper slag of a zinc smelting system; and cooling and crystallizing the solution after removing the fluoride ions and the chloride ions to obtain sodium sulfate so as to remove sodium ions in the solution to obtain a third solution.
According to the embodiment of the invention, zinc is recovered from the zinc electrolysis waste liquid and fluorine and chlorine in the zinc electrolyte are enriched, and the zinc is recovered before the fluorine and chlorine are removed, so that the loss of zinc in the fluorine and chlorine removing process is avoided, and the zinc and the fluorine and chlorine can be completely separated, and on the other hand, the fluorine and chlorine removing effect is further improved by adopting a method of enriching the fluorine and chlorine in the solution. In addition, the remover adopted in the embodiment of the invention has low price and low cost for removing fluorine and chlorine, and can be applied to industrial production.
Drawings
FIG. 1 shows a flow chart of the steps for removing fluorine and chlorine from a zinc electrolyte in an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and detailed description so that the above objects, features and advantages of the present invention can be more clearly understood. The following examples are given for the detailed implementation and specific operation of the present invention, but the scope of the present invention is not limited to the following examples.
The specific experimental procedures or conditions not specified in the examples can be performed according to the procedures or conditions of the conventional experimental procedures described in the prior art in this field. The reagents and other instruments used are not indicated by manufacturers, and are all conventional reagent products which can be obtained commercially.
The inventor of the application finds that the existing method for removing fluorine and chlorine from the zinc electrolyte directly removes fluorine and chlorine from the zinc solution, so that the loss of zinc is large in the removing process, the removing effect of fluorine and chlorine is poor and the treatment cost is high. Based on the above problems, the applicant of the present invention proposes the following main technical concepts: by repeating the steps of leaching and zinc precipitation, zinc in the zinc electrolysis waste liquid is separated out and fluorine and chlorine are enriched, and then the fluorine and chlorine are removed by adopting a fractional precipitation method. Based on the conception, the method for removing the fluorine and the chlorine, provided by the invention, separates the zinc from the solution before the fluorine and the chlorine are removed, reduces the loss amount of the zinc and simultaneously achieves a better fluorine and chlorine removal effect.
Based on the above inventive concept, referring to fig. 1, a flow chart of the steps of the method for removing fluorine and chlorine from zinc electrolyte in the embodiment of the present invention is shown, wherein the method comprises:
step S1, adding the zinc electrolysis waste liquid into a stirring leaching tank, adding zinc-containing smoke dust, taking the zinc electrolysis waste liquid as a zinc leaching agent, and immersing the zinc-containing smoke dust into the zinc electrolysis waste liquid in a steam heating atmosphere to obtain a leaching liquid; filtering the leachate by using a plate press filter to obtain zinc-containing filtrate;
step S2, adding a precipitator into the zinc-containing filtrate, heating by adopting steam to keep the precipitation temperature so as to obtain zinc hydroxide precipitate, and filtering the zinc hydroxide precipitate to obtain a first solution;
the first solution is a filtrate obtained after filtering zinc hydroxide, and the solution obtained after removing the zinc hydroxide contains chloride ions, fluoride ions, sulfate ions, sodium ions existing after adding a precipitator and possibly trace zinc ions.
Step S3, repeating the steps S1-S2 until the fluorine ions and the chlorine ions in the first solution reach the target concentration to obtain a second solution enriched with the fluorine ions and the chlorine ions;
wherein, besides fluoride ions and chloride ions, the second solution also contains certain sulfate and sodium ions and possibly a trace amount of zinc ions.
Step S4, sequentially adding a defluorination agent and a dechlorination agent into the second solution to remove fluoride ions and chloride ions; wherein the defluorinating agent is calcium oxide, and the dechlorinating agent is copper slag of a zinc smelting system;
and step S5, cooling and crystallizing the solution after removing the fluoride ions and the chloride ions to obtain sodium sulfate so as to remove sodium ions in the solution to obtain a third solution.
The third solution is a solution obtained after fluorine, chlorine and sodium are removed, and certain calcium ions, copper ions, trace zinc ions and a large amount of sulfate ions may exist in the solution.
In the embodiment of the invention, the process of leaching zinc-containing smoke dust by using zinc electrolyte and adding precipitator to precipitate zinc is repeated, zinc is recovered before fluorine and chlorine are removed, fluorine ions and chlorine ions are enriched, the loss of zinc in the fluorine and chlorine removal process is avoided, and the enrichment of fluorine ions and chlorine ions is also beneficial to the subsequent fractional precipitation step.
In the embodiment of the invention, the copper slag of the zinc smelting system is a copper simple substance and a copper compound, and the copper slag is added into the solution to enable the copper simple substance to react with copper ions to obtain cuprous ions, so that cuprous chloride precipitate is obtained.
Preferably, in the step S1, the zinc-containing smoke dust is stirred for 0.5-5h at a stirring speed of 50-400 rpm in the process of entering the zinc electrolysis waste liquid.
Preferably, in the precipitation process of step S2, stirring is carried out at a stirring speed of 60rpm-300rpm for 0.2h-2 h.
Preferably, the third solution has a fluoride ion content of less than 50mg/L and a chloride ion content of less than 200 mg/L.
Preferably, the step S4 specifically includes:
step 4-1, adding a defluorinating agent into the solution enriched with fluoride ions and chloride ions in the step S3, and stirring for a first preset time at a steam heating temperature of 60-90 ℃ to remove fluoride ions; wherein the mass ratio of the addition amount of the defluorinating agent to the fluorinion in the solution is 1.5-3.4: 1;
in the embodiment of the invention, the main function of controlling the mass ratio of the addition of the defluorinating agent to the fluorine ions in the solution to be 1.5-3.4:1 is to completely precipitate the chlorine ions in the solution as much as possible, and simultaneously, the pH value of the solution is controlled within a certain range, so that the copper ions in the copper slag added in the subsequent step are prevented from generating copper hydroxide precipitate but cannot precipitate the chlorine ions.
Step 4-2, adding a dechlorinating agent into the solution subjected to the defluorination in the step 4-1, and stirring the solution for a second preset time at the steam heating temperature of 60-90 ℃ to remove chloride ions; wherein the mass ratio of the addition amount of the dechlorinating agent to chloride ions in the solution is 1-3.6: 1.
in the embodiment of the invention, the mass ratio of the addition of the dechlorinating agent to the chloride ions in the solution is controlled to be 1-3.6: the main purpose of 1 is to remove chloride ions as much as possible and to reduce impurity ions in the solution.
Preferably, the stirring for the first preset time includes stirring at a stirring speed of 60rpm to 300rpm for 0.2 to 1 hour.
Preferably, the stirring for the second preset time includes stirring at a stirring speed of 60rpm to 300rpm for 0.2 to 1 hour.
Preferably, the zinc-containing smoke dust in the step 1 comprises boiling furnace smoke dust, rotary kiln volatile smoke dust or multi-hearth furnace roasting smoke dust.
In the embodiment of the invention, zinc-containing smoke dust is leached from zinc electrolysis waste liquid, the used zinc-containing smoke dust is boiling roaster smoke dust, rotary kiln volatile smoke dust or multi-hearth furnace roasting smoke dust, and the zinc-containing smoke dust is zinc-rich smoke dust which needs to be recovered in zinc smelting, and the smoke dust has high fluorine and chlorine contents and can enter a zinc smelting system after fluorine and chlorine are removed. The sulfuric acid in the zinc electrolysis waste liquid is simultaneously used as a leaching agent of zinc in the smoke dust, zinc, fluorine and chlorine in the smoke dust are simultaneously dissolved out and enter a leaching liquid, the zinc in the leaching liquid is precipitated and separated and then returns to a zinc smelting system, the fluorine and the chlorine in the smoke dust are removed together with the fluorine and the chlorine in the zinc electrolyte in the subsequent fluorine and chlorine removal step, and the fluorine and the chlorine in the smoke dust are effectively removed while the zinc in the zinc-containing smoke dust is recovered.
Preferably, the mass ratio of the zinc-containing smoke dust to the zinc electrolysis waste liquid in the step 1 is 1: 1 to 20; the steam heating temperature is 60-90 ℃, and the pH value of the solution is 3.0-6.0 at the end of leaching.
Preferably, the precipitant in the step 2 comprises at least one of sodium hydroxide and sodium carbonate, the mass fraction of the precipitant is 5 wt% to 40 wt%, and the precipitation temperature is 60 to 95 ℃; the pH of the solution at the end of the precipitation is 6.5-8.0.
In the embodiment of the invention, zinc in at least one of sodium hydroxide and sodium carbonate is adopted as a precipitation solution, fluoride ions in lime (CaO) are used as the precipitation solution, chloride ions in a copper slag precipitation solution produced by purifying a zinc smelting solution are used as the chloride ions in the copper slag precipitation solution, the raw materials used for leaching, precipitation and separation are low in price, and the cost for removing fluorine and chlorine is low.
Preferably, the target concentration in the step 3 is 1 g/L.
In the embodiment of the invention, the concentration of the fluorine ions and the chlorine ions is enriched to 1g/L, so that the concentration of the chlorine ions and the fluorine ions in the solution is higher, and the fluorine and chlorine removal effect is better in the fluorine and chlorine removal step.
Preferably, the cooling crystallization method in the step 5 comprises cooling by industrial water circulation, and the temperature of the cooling crystallization is 0-15 ℃.
Preferably, the third solution is added to the electrolyte used in the hydrometallurgical zinc process, so that the third solution is repeatedly applied to the process of obtaining zinc electrolysis waste liquor.
Preferably, the hydroxide precipitate of zinc is used in a hydrometallurgical zinc process to recover zinc.
In order that those skilled in the art will better understand the present invention, one of the present inventions is described below in terms of several specific embodiments.
Example 1:
taking 2m of zinc electrolysis waste liquid with 52g/L zinc content, 180g/L fluorine content and 720g/L chlorine content3Placing the zinc in a stirring leaching tank, and boiling the zincAdding 0.8t of flue dust of a roasting furnace into the zinc electrolysis waste liquid, starting steam for heating, starting a stirrer, controlling the stirring speed to be 300rpm, controlling the leaching temperature to be 95 ℃, controlling the leaching time to be 3h, and controlling the pH value at the leaching end point to be 5.0. And filtering the obtained leachate by using a plate-and-frame filter press, and returning filter residues to a zinc smelting system. Adding a sodium hydroxide solution with the mass concentration of 20 wt% into the zinc-containing filtrate to precipitate zinc, wherein the precipitation temperature is as follows: 85 ℃, precipitation time: 1.2h, stirring speed 260rpm, precipitation end pH 6.7.
Filtering the zinc hydroxide precipitate to obtain a first solution, returning the filtered zinc hydroxide precipitate to a zinc smelting system, returning the first solution to the zinc electrolysis waste liquid, and leaching and precipitating zinc for 10 times to obtain a second solution with the fluorine content of 1.2g/L and the chlorine content of 2.3 g/L.
Adding CaO into the second solution, wherein the adding amount is 1.6 times of the mass of fluorine in the solution, the fluorine and calcium ions in the solution form calcium fluoride precipitate, and the precipitation temperature is as follows: at 78 ℃, precipitation time: 0.5h, stirring speed: 270 rpm.
Adding a zinc smelting solution into the solution after defluorination to purify the produced copper slag, wherein the adding amount of the copper slag is 2 times of the mass of chlorine in the solution by copper, copper ions and copper obtain cuprous ions after the copper slag is dissolved, the cuprous ions and the chloride ions form cuprous chloride precipitate, and the precipitation temperature is as follows: 82 ℃, precipitation time: 40min, stirring speed: 240 rpm. And (3) refrigerating by using an industrial cooling water circulator, reducing the temperature of the solution after removing fluorine and chlorine to 6 ℃, and crystallizing and separating out sodium sulfate in the solution to obtain a third solution.
The fluorine content in the zinc hydroxide precipitate obtained in the treatment process is lower than 0.0014 percent, and the chlorine content is lower than 0.0023 percent. The fluorine content in the solution is lower than 48mg/L, and the chlorine content is lower than 97 mg/L. And adding the third solution into the electrolyte of the zinc hydrometallurgy, and continuously discharging fluorine and chlorine in the zinc electrolyte for 156 times, wherein the fluorine content is reduced to 43mg/L, and the chlorine content is reduced to 88 mg/L.
Example 2:
taking 2.3m zinc electrolysis waste liquid with 58g/L zinc content, 168g/L fluorine content and 686g/L chlorine content3Putting the mixture into a stirring heating tank, taking back 0.87t of the smoke dust volatilized by the rotary kiln, adding the smoke dust into the zinc electrolysis waste liquid, and openingStarting steam heating, starting a stirrer, controlling the stirring speed to be 290rpm, controlling the leaching temperature to be 98 ℃, controlling the leaching time to be 2.5h, and controlling the pH value at the leaching end point to be 5.1. And filtering the obtained leachate by using a plate-and-frame filter press, and returning filter residues to a zinc smelting system. Adding a sodium hydroxide solution with the mass concentration of 25% into the zinc-containing filtrate to precipitate zinc, wherein the precipitation temperature is as follows: 88 ℃, precipitation time: 1.5h, stirring speed 280rpm, precipitation end pH 6.6.
And filtering the zinc hydroxide precipitate to obtain a first solution, returning the filtered zinc hydroxide precipitate to a zinc smelting system, returning the first solution to the zinc electrolysis waste liquid, and leaching and precipitating zinc for 12 times to obtain a second solution with the fluorine content of 1.1g/L and the chlorine content of 2.6 g/L.
Adding CaO into the second solution, wherein the adding amount is 1.7 times of the mass of fluorine in the solution, the fluorine and calcium ions in the solution form calcium fluoride precipitate, and the precipitation temperature is as follows: 85 ℃, precipitation time: 38min, stirring speed: 275 rpm. Adding a zinc smelting solution into the solution after defluorination to purify the produced copper slag, wherein the adding amount of the copper slag is 2.2 times of the mass of chlorine in the solution by copper, copper ions and copper obtain cuprous ions after the copper slag is dissolved, the cuprous ions and the chloride ions form cuprous chloride precipitate, and the precipitation temperature is as follows: precipitation time at 86 ℃: 36min, stirring speed: 256 rpm. And (3) refrigerating by using an industrial cooling water circulator, reducing the temperature of the solution after removing fluorine and chlorine to 7 ℃, and crystallizing and separating out sodium sulfate in the solution to obtain a third solution.
The fluorine content in the zinc hydroxide precipitate obtained in the treatment process is lower than 0.0012 percent, and the chlorine content is lower than 0.0021 percent. The fluorine content in the solution is lower than 47.6mg/L, and the chlorine content is lower than 98.3 mg/L. And adding the third solution into the electrolyte of the zinc hydrometallurgy, and continuously discharging fluorine and chlorine in the zinc electrolyte for 152 times, wherein the fluorine content is reduced to 41mg/L, and the chlorine content is reduced to 87 mg/L.
Example 3:
taking 2.6m zinc electrolysis waste liquid with the zinc content of 57.5g/L, the fluorine content of 181g/L and the chlorine content of 702g/L3Placing in a stirring heating tank, adding 0.91t of multi-hearth furnace roasting smoke dust into zinc electrolysis waste liquid, starting steam for heating, starting a stirrer, stirring at 325rpm, and controlling leaching temperatureThe leaching time is 2.8h at 97 ℃, and the leaching end point pH is 5.6. And filtering the obtained leachate by using a plate-and-frame filter press, and returning filter residues to a zinc smelting system. Adding a sodium hydroxide solution with the mass concentration of 30% into the zinc-containing filtrate to precipitate zinc, wherein the precipitation temperature is as follows: 90 ℃, precipitation time: 1.7h, 292rpm stirring speed, precipitation end pH 6.5.
Filtering the zinc hydroxide precipitate to obtain a first solution, returning the filtered zinc hydroxide precipitate to a zinc smelting system, returning the first solution to the zinc electrolysis waste liquid, and leaching and precipitating zinc for 10 times to obtain a second solution with the fluorine content of 1.4g/L and the chlorine content of 2.8 g/L.
Adding CaO into the second solution, wherein the adding amount is 1.9 times of the mass of fluorine in the solution, the fluorine and calcium ions in the solution form calcium fluoride precipitate, and the precipitation temperature is as follows: 92 ℃, precipitation time: 45min, stirring speed: 283 rpm.
Adding a zinc smelting solution into the solution after defluorination to purify the produced copper slag, wherein the adding amount of the copper slag is 2.3 times of the mass of chlorine in the solution by copper, copper ions and copper obtain cuprous ions after the copper slag is dissolved, the cuprous ions and the chloride ions form cuprous chloride precipitate, and the precipitation temperature is as follows: 90 ℃, precipitation time: 46min, stirring speed: 278 rpm. And (3) refrigerating by using an industrial cooling water circulator, reducing the temperature of the solution after removing fluorine and chlorine to 6 ℃, and crystallizing and separating out sodium sulfate in the solution to obtain a third solution.
The fluorine content in the zinc hydroxide precipitate obtained in the treatment process is lower than 0.001%, and the chlorine content is lower than 0.0011%. The fluorine content in the solution is lower than 46mg/L, and the chlorine content is lower than 95 mg/L. And adding the third solution into the electrolyte of the zinc hydrometallurgy, and continuously discharging fluorine and chlorine in the zinc electrolyte for 166 times, wherein the fluorine content is reduced to 45mg/L, and the chlorine content is reduced to 89 mg/L.
The results of the embodiment show that the zinc hydroxide precipitate with low fluorine and chlorine content can be obtained by the method of firstly precipitating zinc to enrich fluorine and chlorine and then removing fluorine and chlorine, and the zinc hydroxide precipitate is used for subsequent recycling, and fluorine ions and chlorine ions in the solution are better removed, so that the zinc electrolyte with low fluorine and chlorine contents can be obtained when the zinc electrolyte is recycled for more than 100 times, and the abrasion of equipment is reduced.
For simplicity of explanation, the method embodiments are described as a series of acts or combinations, but those skilled in the art will appreciate that the present invention is not limited by the order of acts, as some steps may occur in other orders or concurrently in accordance with the invention. Further, those skilled in the art will appreciate that the embodiments described in the specification are preferred embodiments and that the acts and elements referred to are not necessarily required to practice the invention.
The method for removing fluorine and chlorine from zinc electrolyte provided by the invention is described in detail above, and the principle and the implementation mode of the invention are explained in the text by applying specific examples, and the description of the examples is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.

Claims (10)

1. A method for removing fluorine and chlorine from a zinc electrolyte, which is characterized by comprising the following steps:
step 1, adding zinc electrolysis waste liquid into a stirring leaching tank, adding zinc-containing smoke dust, taking the zinc electrolysis waste liquid as a zinc leaching agent, and soaking the zinc-containing smoke dust into the zinc electrolysis waste liquid in a steam heating atmosphere to obtain a leaching solution; filtering the leachate by using a plate press filter to obtain zinc-containing filtrate;
step 2, adding a precipitator into the zinc-containing filtrate, heating by adopting steam to keep the precipitation temperature so as to obtain zinc hydroxide precipitate, and filtering the zinc hydroxide precipitate to obtain a first solution;
step 3, repeating the steps 1-2 until the fluorine ions and the chloride ions in the first solution reach the target concentration to obtain a second solution enriched with the fluorine ions and the chloride ions;
step 4, sequentially adding a defluorinating agent and a dechlorinating agent into the second solution to remove fluoride ions and chloride ions; wherein the defluorinating agent is calcium oxide, and the dechlorinating agent is copper slag of a zinc smelting system;
and 5, cooling and crystallizing the solution subjected to fluoride ion and chloride ion removal to obtain sodium sulfate so as to remove sodium ions in the solution and obtain a third solution.
2. The method for removing fluorine and chlorine from zinc electrolyte according to claim 1, wherein the third solution has a fluorine ion content of less than 50mg/L and a chlorine ion content of less than 200 mg/L.
3. The method for removing fluorine and chlorine from a zinc electrolyte according to claim 1, wherein the step 4 specifically comprises:
step 4-1, adding a defluorinating agent into the solution enriched with the fluoride ions and the chloride ions in the step 3, and stirring for a first preset time at a steam heating temperature of 60-90 ℃ to remove the fluoride ions; wherein the mass ratio of the addition amount of the defluorinating agent to the fluorinion in the solution is 1.5-3.4: 1;
step 4-2, adding a dechlorinating agent into the solution subjected to the defluorination in the step 4-1, and stirring the solution for a second preset time at the steam heating temperature of 60-90 ℃ to remove chloride ions; wherein the mass ratio of the addition amount of the dechlorinating agent to chloride ions in the solution is 1-3.6: 1.
4. the method for removing fluorine and chlorine from zinc electrolyte according to claim 1, wherein said zinc-containing fumes in step 1 comprise fluidized bed roaster fumes, rotary kiln volatile fumes or multiple hearth furnace roasting fumes.
5. The method for removing fluorine and chlorine from zinc electrolyte according to claim 1, wherein the mass ratio of the zinc-containing smoke dust to the zinc electrolysis waste liquid in the step 1 is 1: 1 to 20; the steam heating temperature is 60-90 ℃, and the pH value of the solution is 3.0-6.0 at the end of leaching.
6. The method for removing fluorine and chlorine from zinc electrolyte according to claim 1, wherein the precipitant in step 2 comprises at least one of sodium hydroxide and sodium carbonate, the mass fraction of the precipitant is 5 wt% to 40 wt%, and the precipitation temperature is 60 to 95 ℃; the pH of the solution at the end of the precipitation is 6.5-8.0.
7. The method for removing fluorine and chlorine from zinc electrolyte according to claim 1, wherein the target concentration in the step 3 is 1 g/L.
8. The method for removing fluorine and chlorine from zinc electrolyte according to claim 1, wherein the cooling crystallization in the step 5 comprises industrial water circulation cooling, and the temperature of the cooling crystallization is 0-15 ℃.
9. The method according to claim 1, characterized in that the third solution is added to the electrolyte used in hydrometallurgical zinc processes, so that the third solution is reused in the process of obtaining zinc electrolysis effluent.
10. The method for removing fluorine and chlorine from zinc electrolyte according to claim 1, wherein said zinc hydroxide precipitate is used in hydrometallurgical zinc processes to recover zinc.
CN202210322037.0A 2022-03-30 2022-03-30 Method for removing fluorine and chlorine from zinc electrolyte Pending CN114672664A (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102286759A (en) * 2011-07-31 2011-12-21 红河锌联科技发展有限公司 Method for preparing electrodeposited zinc from high-fluorine high-chlorine secondary zinc oxide powder
CN105112660A (en) * 2015-10-16 2015-12-02 江西理工大学 Method for removing fluorine and chlorine in zinc sulfate solution
CN109487082A (en) * 2018-12-24 2019-03-19 有研工程技术研究院有限公司 A method of taking off fluorine and chlorine removal from zinc electrolyte
CN112877736A (en) * 2021-01-14 2021-06-01 白银有色集团股份有限公司 Method for removing fluorine and chlorine from zinc hydrometallurgy electrolysis circulating liquid

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102286759A (en) * 2011-07-31 2011-12-21 红河锌联科技发展有限公司 Method for preparing electrodeposited zinc from high-fluorine high-chlorine secondary zinc oxide powder
CN105112660A (en) * 2015-10-16 2015-12-02 江西理工大学 Method for removing fluorine and chlorine in zinc sulfate solution
CN109487082A (en) * 2018-12-24 2019-03-19 有研工程技术研究院有限公司 A method of taking off fluorine and chlorine removal from zinc electrolyte
CN112877736A (en) * 2021-01-14 2021-06-01 白银有色集团股份有限公司 Method for removing fluorine and chlorine from zinc hydrometallurgy electrolysis circulating liquid

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