CN116356149A

CN116356149A - Method for selectively separating thallium from thallium-containing high-fluorine chlorine smoke dust and application thereof

Info

Publication number: CN116356149A
Application number: CN202310205233.4A
Authority: CN
Inventors: 闵小波; 柴立元; 伍莞澜; 柯勇; 彭聪; 李云; 王云燕; 刘朗明; 刘卫平; 林璋; 李青竹; 林文军; 王浩宇
Original assignee: Central South University; Zhuzhou Smelter Group Co Ltd
Current assignee: Central South University; Zhuzhou Smelter Group Co Ltd
Priority date: 2023-03-02
Filing date: 2023-03-02
Publication date: 2023-06-30

Abstract

The invention provides a method for selectively separating thallium from thallium-containing high-fluorine chlorine smoke dust and application thereof, wherein the method comprises the following steps: alkaline leaching is carried out on thallium-containing high-fluorine chlorine smoke dust in alkaline leaching liquid, and alkaline leaching post-alkaline leaching matter and thallium-containing leaching liquid are obtained, wherein hydroxide ions are contained in the alkaline leaching liquid. Roasting the alkaline leaching product at 700-800 deg.c to obtain roasted product and thallium-containing gas. Thallium in the thallium-containing high-fluorine chlorine dust mainly exists in the form of monovalent thallium, and the components in the thallium-containing high-fluorine chlorine dust comprise lead-zinc sulfate, lead-zinc oxide and lead-zinc fluorine-chlorine compound. In the method, the alkaline leaching converts the zinc sulfate structure into the zinc hydroxide structure, so as to realize the release of thallium. Thallium in the slag after alkaline leaching mainly exists in the form of simple compounds, thallium volatilizes faster at 700-800 ℃, and compounds corresponding to lead, zinc and cadmium in the slag after alkaline leaching are basically not volatilized, so that thallium can be selectively separated from other substances in thallium-containing high fluorine chlorine smoke dust.

Description

Method for selectively separating thallium from thallium-containing high-fluorine chlorine smoke dust and application thereof

Technical Field

The invention relates to the technical field of comprehensive utilization and treatment of thallium-containing materials, in particular to a method for selectively separating thallium from thallium-containing high-fluorine chlorine smoke dust and application thereof.

Background

Thallium is a typical rare dispersing element found in nature and is widely found in primary metal minerals. Thallium has various characteristics of improving alloy strength, improving alloy hardness, enhancing alloy corrosion resistance and the like, and thallium-containing alloy has potential application value in the aspects of optical fibers, superconducting materials, infrared optical materials, radiation shielding materials, catalysts and the like. However, the annual global thallium usage is less than 30 tons, which results in a lack of enthusiasm for thallium production enterprises. In nonferrous metallurgy, ferrous metallurgy and chemical industry production processes, the discharge of thallium-containing wastewater and the treatment and recycling of a large amount of thallium-containing waste residues bring great risks to thallium pollution in the ecological environment.

At present, the research on the separation and enrichment of thallium in thallium-containing materials is mainly focused on thallium-containing minerals and thallium-containing waste residues, and the research on thallium-containing high-fluorine chlorine smoke dust is less. The separation and enrichment method generally has the problems of long steps and complicated steps.

Disclosure of Invention

The invention mainly aims to provide a method for selectively separating thallium from thallium-containing high-fluorine chlorine smoke dust and application thereof, so as to solve the technical problem of efficiently separating thallium from thallium-containing high-fluorine chlorine smoke dust.

To achieve the above object, the present invention provides in a first aspect a method for selectively separating thallium from thallium-containing high fluorine chlorine dust, comprising:

and (3) alkaline leaching the thallium-containing high-fluorine chlorine smoke dust in alkaline leaching liquid until zinc sulfate in the thallium-containing high-fluorine chlorine smoke dust is changed into zinc hydroxide, so as to obtain alkaline leaching substances and thallium-containing leaching liquid, wherein the alkaline leaching liquid comprises hydroxide ions.

Roasting the alkaline leaching product at 700-800 deg.c to obtain roasted product and thallium-containing gas.

Thallium in the thallium-containing high-fluorine chlorine dust mainly exists in the form of monovalent thallium, and the components in the thallium-containing high-fluorine chlorine dust comprise lead-zinc sulfate, lead-zinc oxide and lead-zinc fluorine-chlorine compound.

According to embodiments of the present application, the liquid-to-solid ratio of the alkaline leaching solution to the thallium-containing high fluorine chlorine dust is greater than 10:1.

According to an embodiment of the present application, the concentration of hydroxide ions in the alkaline leaching solution is 0.3mol/L to 0.5mol/L.

According to an embodiment of the present application, the alkaline leaching solution is a sodium hydroxide solution and/or a potassium hydroxide solution.

According to the embodiment of the application, the reaction temperature of thallium-containing high fluorine chlorine dust in alkaline leaching solution is 50-80 ℃ and the reaction time is more than 2 hours.

According to the embodiment of the application, the alkaline leaching product is roasted under the non-reducing atmosphere condition, and the heat preservation time is more than or equal to 30min.

According to an embodiment of the present application, the thallium-containing high fluorine chlorine dust further comprises, prior to the alkaline leaching:

and drying and grinding thallium-containing high-fluorine chlorine smoke dust.

According to an embodiment of the present application, the step of grinding thallium-containing high fluorine chlorine dust after drying comprises:

drying thallium-containing high fluorine chlorine smoke dust to constant weight at 60-90 ℃, and grinding to 100-400 meshes.

According to an embodiment of the present application, smelting the baked good is also included.

In a second aspect, the invention provides the use of the method described above for selectively separating thallium from thallium-containing high fluorine chlorine fumes.

In the method for selectively separating thallium from thallium-containing high-fluorine chlorine dust, the thallium in the thallium-containing high-fluorine chlorine dust has strong correlation with zinc sulfate, and alkaline leaching converts the zinc sulfate structure into a zinc hydroxide structure, so that thallium release is realized, and thallium-containing leaching liquid is obtained. Thallium in the slag after alkaline leaching mainly exists in the form of simple compounds, thallium volatilizes faster at 700-800 ℃, and compounds corresponding to lead, zinc and cadmium in the slag after alkaline leaching are basically not volatilized, so that thallium can be selectively separated from other substances in thallium-containing high fluorine chlorine smoke dust. The method for selectively separating thallium from thallium-containing high-fluorine chlorine smoke dust has simple process and good separation effect.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.

FIG. 1 is an XRD pattern of thallium-containing high fluorine chlorine dust in example 1 of the present invention;

FIG. 2 is a graph showing the chemical phase analysis results of the water-soluble zinc and the zinc oxide according to the change of the roasting temperature and the change rule of the thallium volatilization rate in the embodiment 2 of the present invention;

FIG. 3 is a graph showing the results of chemical phase analysis of the change of lead in chloride form, lead in sulfate form and lead in oxide form with the firing temperature and the change of thallium volatilization rate in example 2 of the present invention;

FIG. 4 is a graph showing the chemical phase analysis results of the water-soluble zinc and the zinc oxide according to the oxygen concentration and the thallium volatilization rate in example 3;

FIG. 5 is a graph showing the chemical phase analysis results of the change of the concentration of oxygen and the change of the volatilization rate of thallium of example 3 of the present invention;

FIG. 6 is an XRD pattern of the slag after alkaline leaching in an embodiment of the present invention.

The achievement of the object, functional features and advantages of the present invention will be further described with reference to the drawings in connection with the embodiments.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, are intended to fall within the scope of the present invention.

It should be noted that all directional indicators (such as upper and lower … …) in the embodiments of the present invention are merely used to explain the relative positional relationship, movement conditions, etc. between the components in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indicator is changed accordingly.

Furthermore, descriptions such as those referred to as "first," "second," and the like, are provided for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implying an order of magnitude of the indicated technical features in the present disclosure. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature.

Moreover, the technical solutions of the embodiments of the present invention may be combined with each other, but it is necessary to be based on the fact that those skilled in the art can implement the embodiments, and when the technical solutions are contradictory or cannot be implemented, it should be considered that the combination of the technical solutions does not exist, and is not within the scope of protection claimed by the present invention.

In a first aspect, the invention provides a method for selectively separating thallium from thallium-containing high fluorine chlorine dust comprising:

and S100, alkaline leaching thallium-containing high-fluorine chlorine smoke dust in alkaline leaching liquid until zinc sulfate in the thallium-containing high-fluorine chlorine smoke dust is changed into zinc hydroxide, so as to obtain alkaline leaching post-matters (also called alkaline leaching post-slag) and thallium-containing leaching liquid, wherein hydroxide ions are included in the alkaline leaching liquid. Thallium in the thallium-containing high-fluorine chlorine dust mainly exists in the form of monovalent thallium, and the components in the thallium-containing high-fluorine chlorine dust comprise lead-zinc sulfate, lead-zinc oxide and lead-zinc fluorine-chlorine compound.

And S200, roasting the alkaline leaching product at 700-800 ℃ to obtain a roasted product (also called as roasted slag) and thallium-containing gas.

The thallium-containing high-fluorine chlorine smoke dust is mainly collected from the zinc oxide defluorination process of lead-zinc smelting enterprises. The thallium content of the thallium-containing high fluorine chlorine dust is 0.5 to 0.7 weight percent, and thallium mainly exists in the form of monovalent thallium. In order to achieve selective separation of thallium, conditions for volatilization of thallium compounds are required to be satisfied thermodynamically and kinetically, so that selective separation of thallium is achieved in consideration of a combination of alkaline leaching and medium temperature roasting.

The alkaline leaching treatment is selected for several reasons: 1) The research shows that thallium in thallium-containing high-fluorine chlorine smoke dust has strong correlation with zinc sulfate, thallium separation can be realized by destroying the zinc sulfate structure, and alkaline leaching liquid used for alkaline leaching comprises hydroxide ions, for example, the alkaline leaching liquid can be prepared from one or more substances of sodium hydroxide, potassium hydroxide and the like. Thus, alkaline leaching can change the zinc sulfate structure into a zinc hydroxide structure, and release of thallium is realized.

2) In the alkaline leaching process, lead, zinc and cadmium are all converted into hydroxides to enter slag, thallium hydroxide is soluble, and selective separation of thallium can be realized. Neutral leaching and acid leaching do not meet the objectives of both selective leaching and thallium selective leaching.

3) The alkaline leaching process can convert the fluorine-chlorine compounds of valuable metals in the smoke dust into sodium salts, so that fluorine and chlorine elements enter the solution in the form of salts, and volatilization of the fluorine-chlorine compounds of the valuable metals in the subsequent roasting process is reduced.

4) The reaction rate can be greatly improved by increasing the temperature in the leaching process, and meanwhile, the alkali leaching solution and the elements in the smoke dust can fully react by controlling the volume ratio of the alkali leaching solution to the smoke dust, so that the thallium leaching rate and the conversion rate of valuable metals such as lead, zinc, cadmium and the like are improved. Therefore, the above points are combined, and it is determined to use alkaline leaching as a pretreatment means.

And (3) alkaline leaching the thallium-containing high-fluorine chlorine smoke dust in alkaline leaching liquid until zinc sulfate in the thallium-containing high-fluorine chlorine smoke dust becomes zinc hydroxide. The endpoint of the alkaline leaching reaction is determined by the change of zinc sulfate to zinc hydroxide. The concentration, amount and immersion time of the alkaline leaching solution are all adjusted by changing the final zinc sulfate into zinc hydroxide. For example, the concentration of the alkaline leaching solution is low, the dosage of the alkaline leaching solution can be increased appropriately, the soaking time can be prolonged appropriately, the concentration of the alkaline leaching solution is high, the dosage of the alkaline leaching solution can be reduced appropriately, and the soaking time can be shortened appropriately.

The particle size of the thallium-containing high-fluorine chlorine dust also affects the alkaline leaching effect to a certain extent, and no matter the particle size, the alkaline leaching needs to ensure that zinc sulfate in the thallium-containing high-fluorine chlorine dust is changed into zinc hydroxide. Illustratively, when the particles of the thallium-containing high-fluorine chlorine dust are small, the contact area of the thallium-containing high-fluorine chlorine dust with the alkaline leaching solution is large, the alkaline leaching solution concentration may be relatively low, the amount thereof may be reduced by a proper amount, and the leaching time may be shortened by a proper amount. Illustratively, when the particles of the thallium-containing high-fluorine chlorine dust are large, the contact area of the thallium-containing high-fluorine chlorine dust with the alkaline leaching solution is small, the alkaline leaching solution concentration may be relatively high, the amount thereof may be appropriately increased, and the soaking time may be appropriately prolonged.

The thallium content of the slag after alkaline leaching is about 0.10wt%, and the leaching rate of thallium cannot be further improved by optimizing the relevant parameters of alkaline leaching, so that other means are necessary to realize the deep separation of thallium in the slag. Through investigation, thallium compounds have lower volatilization temperature, so that selective separation of thallium is realized by adopting medium-temperature roasting. The roasting temperature and the heat preservation time are regulated and controlled, and the selective volatilization of thallium can be effectively realized within a certain range by controlling related parameters.

The following reasons exist for determining that the volatilization temperature is between 700 and 800 ℃ and the roasting atmosphere is a non-reducing atmosphere: 1) The alkaline leaching process damages the zinc sulfate phase, so thallium in the slag after alkaline leaching mainly exists in the form of simple compounds, and volatilizes at the temperature of above 600 ℃ and volatilizes strongly at the temperature of 700 ℃; 2) Lead, zinc and cadmium in the slag are mainly in hydroxide form, and are decomposed into oxides of corresponding metals in a high-temperature process, and the lead, the zinc and the cadmium volatilize to a certain extent at the temperature higher than 800 ℃. The above points are combined, and the medium temperature roasting temperature is controlled to be 700-800 ℃.

The invention provides a method for selectively separating thallium from thallium-containing high-fluorine chlorine smoke dust, which can effectively avoid pollution of thallium-containing high-fluorine chlorine smoke dust to the environment, and can selectively recover valuable metals from thallium-containing high-fluorine chlorine smoke dust to the greatest extent. The alkaline leaching-medium temperature roasting combined treatment damages the structure of thallium-containing phases, realizes the selective separation of thallium, and simultaneously reduces the temperature of the subsequent roasting process and the volatilization rate of valuable metals such as lead, zinc and the like. Compared with other treatment methods, the separation efficiency of valuable metals and thallium is higher. The thallium-removed slag obtained after volatilization can be returned to a lead-zinc smelting system for secondary utilization, thereby realizing the recovery of valuable metals and greatly reducing the environmental risk of thallium-containing high-fluorine chlorine smoke dust.

In the method for selectively separating thallium from thallium-containing high-fluorine chlorine dust, the thallium in the thallium-containing high-fluorine chlorine dust has strong correlation with zinc sulfate, and alkaline leaching converts the zinc sulfate structure into a zinc hydroxide structure, so that thallium release is realized, and thallium-containing leaching liquid is obtained. Thallium in the slag after alkaline leaching mainly exists in the form of simple compounds, the volatilization is fast at 700-800 ℃, and compounds corresponding to lead, zinc and cadmium in the slag after alkaline leaching are basically not volatilized, so that thallium can be selectively separated from other substances in thallium-containing high fluorine chlorine smoke dust. The method for selectively separating thallium from thallium-containing high-fluorine chlorine smoke dust has simple process and good separation effect.

In some embodiments, the liquid to solid ratio of the alkaline leaching solution to the thallium containing high fluorine chlorine dust is greater than 10:1.

In some embodiments, the concentration of hydroxide ions in the caustic leach solution is between 0.3mol/L and 0.5mol/L.

It is necessary to control the alkali leaching solution concentration between 0.3M and 0.5M, the alkali liquor with lower concentration can lead to incomplete valuable metal reaction and higher leaching rate, and the excessive alkali concentration can lead to reverse leaching of valuable metal hydroxide precipitate and cause reverse leaching rate of valuable metal. Thus, a suitable alkaline leaching solution concentration is necessary to disrupt the structure of the thallium containing phase, achieving selective leaching of thallium.

In some embodiments, the caustic dip is a sodium hydroxide solution and/or a potassium hydroxide solution.

In some embodiments, the thallium-containing high fluorine chlorine dust is reacted in alkaline leaching solution at a reaction temperature of 50-80 ℃ for more than 2 hours.

In some embodiments, the alkaline leaching product is baked under non-reducing atmosphere conditions, and the heat preservation time is more than or equal to 30 minutes.

The metal oxide can be partially reduced into metal simple substance under the reducing atmosphere, and certain volatilization exists under the medium temperature condition. Thus, calcination under non-reducing atmosphere conditions is selected.

In some embodiments, the thallium-containing high fluorine chlorine dust further comprises, prior to the alkaline leaching:

and drying and grinding thallium-containing high-fluorine chlorine smoke dust.

In some embodiments, the step of grinding the thallium-containing high fluorine chlorine dust after drying comprises:

In some embodiments, smelting the post-baked good is also included.

Example 1

Sampling analysis of thallium-containing high-fluorine chlorine smoke dust

And (3) drying (an 80 ℃ air blast drying box) the thallium-containing high-fluorine-chlorine smoke dust to constant weight, grinding (grinding to 100-mesh sieve), digesting the ground thallium-containing high-fluorine-chlorine smoke dust by using hydrochloric acid, nitric acid and ammonium bifluoride, measuring the element content in the thallium-containing high-fluorine-chlorine smoke dust, and carrying out phase analysis.

In this example, the thallium content of the thallium-containing high fluorine chlorine dust was measured to be 0.66wt%. The thallium element in the thallium-containing high-fluorine chlorine smoke dust is unevenly distributed, the thallium content of the whole smoke dust is between 0.5 and 0.7 weight percent, and the calculation of the volatilization rate of thallium in the subsequent examples and comparative examples takes the content obtained by digestion as a calculation standard.

The specific analysis results are as follows:

1. referring to fig. 1 and chemical phase analysis, in this example, the phases in which thallium-containing high fluorine chlorine dust mainly exists include zinc oxide, lead oxide, zinc sulfate (water-soluble zinc), lead sulfate, lead chloride, zinc chloride, and the like, and the existence forms include crystalline and amorphous states.

2. In the embodiment, the mass percentages of main elements in the thallium-containing high-fluorine chlorine smoke dust are shown in the following table:

element(s)	Zn	Pb	S	Cd	Fe	F	Tl	Cl	O
										Content (%)	38.1	17.75	6.135	1.98	3.22	0.93	0.66	4.87	22.5

As can be seen from the above table, the thallium-containing high-fluorine chlorine dust mainly contains valuable metal elements such as Zn, pb and the like.

3. In this example, the chemical phase analysis results (mass%) of Zn are shown with reference to the following table:

4. in this example, the chemical phase analysis results (mass percent) of Pb are shown with reference to the following table:

example 2

Temperature single factor test

1kg of a sample of thallium-containing high fluorine chlorine dust (same as in example 1) dried (80 ℃ C. Forced air drying oven) to a constant weight was ground (to a 100 mesh sieve) to obtain a ground product.

The ground product was calcined at 600 ℃,700 ℃, 800 ℃, 900 ℃, 1000 ℃ and 1100 ℃ respectively.

The process of each roasting is as follows: 15g of ground product is put into a vertical tube furnace for roasting under the air atmosphere; the temperature of each roasting is controlled to be respectively the above temperatures, the heat preservation time of each roasting is 1h, and the baked slag is cooled to the room temperature along with the furnace after the roasting.

In this example, the results of chemical phase analysis of water-soluble zinc and zinc oxide in the post-baking slag as a function of baking temperature (mass ratio in the post-baking slag), and the law of change in thallium volatilization rate (as a function of baking temperature) are shown in FIG. 2.

The results of chemical phase analysis of the change of the chlorinated lead, the sulfuric acid lead and the oxidized lead with the roasting temperature (the mass ratio in the slag after roasting) and the change rule of the thallium volatilization rate (the change with the roasting temperature) in the slag after roasting are shown in fig. 3.

Example 3

Oxygen concentration single factor experiment

The ground product was calcined at oxygen concentrations of 0%, 10%, 20%, 30%, 40% and 50%, respectively.

Each roasting process is as follows: taking 15g of ground product and roasting in a vertical tube furnace under the oxygen concentration; the roasting temperature is controlled to be 900 ℃, the heat preservation time of each roasting is 1h, and the slag after roasting is cooled to room temperature along with the furnace.

In this example, the results of chemical phase analysis of water-soluble zinc and zinc oxide in the post-baking slag as a function of oxygen concentration (mass ratio in the post-baking slag), and the law of change in thallium volatilization rate as a function of oxygen concentration are shown in FIG. 4.

The results of chemical phase analysis of the change in oxygen concentration of chlorinated lead, sulfuric acid lead and oxidized lead in the post-baking slag (mass ratio in the post-baking slag), and the change law of thallium volatilization rate (change with oxygen concentration) are shown in fig. 5.

Example 4

Water immersion test

Weighing 0.2000g of ground product, placing into a centrifuge tube, adding 50ml of deionized water into the centrifuge tube, placing into a water bath shaking table (150 r/min) at normal temperature, oscillating for 2 hours, taking out, centrifuging, separating solid from liquid, and taking supernatant to test thallium and zinc content.

The leaching rate is calculated by combining the two, and the mass leaching rate is shown in the following table:

thallium leaching Rate (%)	Leaching rate of zinc in water-soluble state (%)
		98.61	100

Analytical example 1

Analysis of thallium-occupiant phases in connection with examples 1-4

1. Referring to fig. 2-5, in the analysis and test results of the two single factor experiments, thallium volatilization rates all show obvious correlation with zinc-containing phases, but have weaker correlation with lead-containing phases, and regularity is not obvious. It is therefore assumed that thallium presence has a certain correlation with zinc phase.

Further, referring specifically to fig. 2, as the temperature increases, the water-soluble zinc phase decreases, the zinc oxide phase increases, and the thallium volatilization rate increases, presumably during the temperature increase, the water-soluble zinc phase converts to the zinc oxide phase and simultaneously releases thallium.

Referring specifically to fig. 4, in the oxygen concentration single factor experiment, the water-soluble zinc phase increases and then decreases, while the oxidation state zinc phase and thallium volatilization rate decrease and then increase, and it is also presumed that the inter-phase transformation between the water-soluble zinc phase and the oxidation state zinc phase results.

As is clear from the data of the water leaching experiment, in the water leaching process, the water-soluble zinc is completely dissolved, and thallium is almost completely dissolved, and analysis shows that the thallium existing in the water leaching process is released due to the destruction of the water-soluble zinc phase structure in the water leaching process, so that the thallium is dissolved simultaneously.

Since the dissolution relationship between water-soluble zinc and thallium and the change law in the roasting process are strongly correlated, the occurrence of thallium is considered to have a strong correlation with the water-soluble zinc phase.

The water-soluble zinc related in the invention is zinc chloride and zinc sulfate by combining main elements related to thallium-containing high fluorine chlorine smoke dust. Wherein, the volatilization temperature of the zinc chloride phase is lower (about 500 ℃ is obviously volatilized), and the decomposition temperature of the zinc sulfate phase is higher (about 500-600 ℃ is dissociated and 930 ℃ is dissociated violently).

In the temperature single factor experiment, along with the temperature rise, the water-soluble zinc phase is continuously reduced after the temperature exceeds 500 ℃, the water-soluble zinc phase is obviously reduced in the range of 900-1000 ℃ (the severe dissociation temperature of zinc sulfate), and meanwhile, the thallium volatilization rate is obviously improved.

Therefore, it is considered that the thallium occurrence is correlated with the zinc sulfate phase, and the thallium occurrence phase in the thallium-containing high-fluorine chlorine dust is zinc sulfate.

Example 5

Sampling and analyzing the slag after alkaline leaching:

the residue after alkaline leaching was digested with hydrochloric acid, nitric acid and ammonium bifluoride, and the thallium content in the residue after alkaline leaching was measured to be 0.10wt% (it should be noted here that the thallium element in the residue after alkaline leaching was unevenly distributed, and the thallium content of the whole was between 0.07 and 0.10 wt%). In addition, the slag after alkaline leaching mainly contains valuable metal elements such as Zn, pb, cd and the like. See fig. 6 and the table below.

Element(s)	Zn	Pb	S	Cd	Fe	Na	Tl	Cl
									Content (%)	45.7	25.7	2.90	1.71	2.68	0.91	0.10	1.11

Comparing the mass percentages of the main elements in the thallium-containing high-fluorine chlorine smoke dust and the slag after alkaline leaching shows that the thallium content of the slag after alkaline leaching is reduced, which means that the thallium content of the thallium-containing high-fluorine chlorine smoke dust is greatly reduced after alkaline leaching and a large amount of thallium enters the leaching solution. The zinc content of the slag after alkaline leaching is increased because zinc in thallium-containing high-fluorine chlorine cigarettes is converted into zinc hydroxide and enters the slag after alkaline leaching.

Example 6

1kg of dried thallium-containing high-fluorine chlorine smoke dust sample is ground, ground and sieved by a 200-mesh sieve. 2.00g of thallium-containing high-fluorine chlorine smoke dust is weighed, 20mL of 0.4M NaOH alkaline leaching solution is added, and the mixture is placed in a shaking table at 80 ℃ for shaking for 2 hours. And standing, cooling, and carrying out suction filtration to obtain residues after alkaline leaching and thallium-containing leaching liquid. The leaching rate of thallium is 89.04%, and the leaching rates of lead, zinc and cadmium are 2.95%, 0.06% and 0.17% respectively.

The obtained slag is dried and ground, then is sieved by a 200-mesh sieve, and is placed in a vertical furnace for roasting. The temperature is controlled to be 800 ℃, and the heat is preserved for 1h under the air atmosphere condition, so as to obtain baked slag and thallium-containing gas. After roasting, the slag is cooled to room temperature along with the furnace.

The baked slag is digested by hydrochloric acid, nitric acid and ammonium bifluoride, the thallium content in the digestion liquid is measured, and the calculated thallium volatilization rate is 99.75%, and the lead, zinc and cadmium volatilization rates are 12.82%, 3.49% and 5.58% respectively.

The volatilization rate calculation step of each element comprises the following steps:

and calculating the content of each element in the slag after alkaline leaching through the content of each element in the thallium-containing high-fluorine chlorine smoke dust and the difference value of the content of each element in the leaching liquid.

And obtaining the content of each volatilized element by calculating the difference between the content of each element in the residue after alkaline leaching and the content of each element in the digestion liquid.

The content of each volatilized element is divided by the content of each element in the slag after alkaline leaching to obtain the volatilization rate of each element.

Example 7

1kg of dried thallium-containing high-fluorine chlorine smoke dust sample is ground, ground and sieved by a 200-mesh sieve. 2.00g of thallium-containing high-fluorine chlorine smoke dust is weighed, 20mL of 0.3M NaOH alkaline leaching solution is added, and the mixture is placed in a shaking table at 50 ℃ for shaking for 2 hours. And standing, cooling, and carrying out suction filtration to obtain residues after alkaline leaching and thallium-containing leaching liquid. The leaching rate of thallium is 82.93% and the leaching rates of lead, zinc and cadmium are 0.05%, 0.04% and 14.41% respectively.

The obtained slag is dried and ground, then is sieved by a 200-mesh sieve, and is placed in a vertical furnace for roasting. The temperature is controlled to be 700 ℃, and the heat is preserved for 1h under the air atmosphere condition, so as to obtain baked slag and thallium-containing gas. After roasting, the slag is cooled to room temperature along with the furnace.

And (3) digesting the baked slag, measuring the thallium content in the digestion liquid, and calculating to obtain the thallium volatilization rate of 97.56 percent and lead, zinc and cadmium volatilization rates of 15.43 percent, 4.91 percent and 8.56 percent respectively.

Example 8

The obtained slag is dried and ground, then is sieved by a 200-mesh sieve, and is placed in a vertical furnace for roasting. Controlling the temperature to 700 ℃ and preserving the temperature for 30min under the air atmosphere condition to obtain baked slag and thallium-containing gas. After roasting, the slag is cooled to room temperature along with the furnace.

And (3) digesting the baked slag, measuring the thallium content in the digestion liquid, and calculating to obtain the thallium volatilization rate of 93.67%, and lead, zinc and cadmium volatilization rates of 2.30%, 4.87% and 8.35% respectively.

Comparative example 1

1kg of dried thallium-containing high-fluorine chlorine smoke dust sample is ground, ground and sieved by a 200-mesh sieve. 2.00g of thallium-containing high-fluorine chlorine smoke dust are weighed, 10mL of 0.1M NaOH alkaline leaching solution is added, and the mixture is placed in a shaking table at 80 ℃ for shaking for 2 hours. And (5) standing, cooling, and carrying out suction filtration, wherein the leaching rate of thallium in the leaching solution is 49.44%.

Based on this comparative example, it was found that it is necessary to control the liquid-solid ratio to 10:1 or more, and when the liquid-solid ratio is low, the slag-liquid reaction is incomplete, the occurrence of thallium is not completely destroyed, thallium is not completely released, and therefore the thallium leaching rate is low. Thus, a higher liquid-to-solid ratio is necessary to disrupt the structure of the thallium containing phase and achieve selective leaching of thallium.

Comparative example 2

1kg of dried thallium-containing high-fluorine chlorine smoke dust sample is ground, ground and sieved by a 200-mesh sieve. 2.00g of thallium-containing high-fluorine chlorine smoke dust is weighed, 20mL of 0.05M NaOH alkaline leaching solution is added, and the mixture is placed in a shaking table at 80 ℃ for shaking for 2 hours. After standing and cooling, leaching, the leaching rate of thallium is 87.92%, and the leaching rates of lead, zinc and cadmium are 0.11%, 12.86% and 62.99% respectively.

Based on the comparative example, it is known that it is necessary to control the alkali leaching solution concentration between 0.3M and 0.5M, the reaction of the valuable metal is incomplete due to the alkali solution with lower concentration, the leaching rate is high, and the precipitation and dissolution of the valuable metal hydroxide are reversely caused by the excessive alkali concentration, so that the leaching rate of the valuable metal is reversely increased. Thus, a suitable alkaline leaching solution concentration is necessary to disrupt the structure of the thallium containing phase, achieving selective leaching of thallium.

Comparative example 3

1kg of dried thallium-containing high-fluorine chlorine smoke dust sample is ground, ground and sieved by a 200-mesh sieve. 2.00g of thallium-containing high-fluorine chlorine smoke dust is weighed, 20mL of 0.3M NaOH alkaline leaching solution is added, and the mixture is placed in a shaking table at 25 ℃ for shaking for 2 hours. After standing and cooling, leaching, the leaching rate of thallium is 57.81%, and the leaching rates of lead, zinc and cadmium are 0.02%, 0.01% and 2.45% respectively.

Based on this comparative example, it was found that it is necessary to control the alkaline leaching temperature between 50 and 80 ℃, the lower temperature would result in incomplete reaction of the system, the thallium leaching rate is lower, and the excessively high temperature would cause complexation of the generated valuable metal precipitate with chloride ions and hydroxide ions in the solution, resulting in a reverse increase in the leaching rate of the valuable metal. Thus, a suitable leaching temperature interval is necessary for destroying the structure of the thallium containing phase, achieving selective leaching of thallium.

Comparative example 4

1kg of dried thallium-containing high-fluorine chlorine smoke dust sample is ground, ground and sieved by a 200-mesh sieve. 2.00g of thallium-containing high-fluorine chlorine smoke dust is weighed, 20mL of 0.4M NaOH alkaline leaching solution is added, and the mixture is placed in a shaking table at 80 ℃ for shaking for 2 hours. After standing and cooling, leaching, the leaching rate of thallium is 89.04%, and the leaching rates of lead, zinc and cadmium are 2.95%, 0.06% and 0.17% respectively. The obtained slag is dried and ground, then is sieved by a 200-mesh sieve, and is placed in a vertical furnace for roasting. The temperature is controlled to 1100 ℃, the heat is preserved for 1h under the air atmosphere condition, and the slag is cooled to the room temperature along with the furnace after roasting. And (3) digesting the baked slag, measuring the thallium content in the digestion liquid, and calculating to obtain the thallium volatilization rate of 99.88%, and lead, zinc and cadmium volatilization rates of 33.39%, 3.20% and 12.33% respectively.

Based on this comparative example, it was found that it is necessary to control the roasting temperature of the alkaline leaching residue to 700 to 800 c, and the thallium volatilization temperature is not reached at a low temperature, resulting in incomplete thallium volatilization, and too high a temperature increases the volatilization rate of the valuable metal, failing to achieve selective separation of thallium from the valuable metal. Thus, a suitable firing temperature interval is necessary to achieve selective separation of thallium and valuable metals.

In the above technical solution of the present invention, the above is only a preferred embodiment of the present invention, and therefore, the patent scope of the present invention is not limited thereto, and all the equivalent structural changes made by the description of the present invention and the content of the accompanying drawings or the direct/indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for selectively separating thallium from thallium-containing high fluorine chlorine dust comprising:

alkaline leaching thallium-containing high-fluorine chlorine smoke dust in alkaline leaching liquid until zinc sulfate in the thallium-containing high-fluorine chlorine smoke dust is changed into zinc hydroxide, so as to obtain alkaline leached substances and thallium-containing leaching liquid, wherein the alkaline leaching liquid comprises hydroxide ions;

roasting the alkaline leaching product at 700-800 ℃ to obtain a roasted product and thallium-containing gas;

the thallium in the thallium-containing high-fluorine chlorine dust mainly exists in the form of monovalent thallium, and the components in the thallium-containing high-fluorine chlorine dust comprise lead-zinc sulfate, lead-zinc oxide and lead-zinc fluorine-chlorine compound.

2. A method according to claim 1, characterized in that the liquid-to-solid ratio of the alkaline leaching solution to the thallium-containing high fluorine chlorine dust is greater than 10:1.

3. The method according to claim 1, wherein the concentration of hydroxide ions in the alkaline leaching solution is 0.3mol/L to 0.5mol/L.

4. The method according to claim 1, characterized in that the alkaline leaching solution is a sodium hydroxide solution and/or a potassium hydroxide solution.

5. The method according to claim 1, wherein the thallium-containing high-fluorine chlorine dust is reacted at a reaction temperature of 50 to 80 ℃ for a reaction time of 2 hours or more in the alkaline leaching solution.

6. The method according to any one of claims 1 to 5, wherein the alkaline leaching product is calcined under a non-reducing atmosphere and the incubation time is not less than 30min.

7. A method according to claim 1 wherein the thallium-containing high fluorine chlorine dust further comprises, prior to the alkaline leaching:

and drying and grinding thallium-containing high-fluorine chlorine smoke dust.

8. A method as set forth in claim 7 wherein the step of drying and grinding thallium-containing high fluorine chlorine dust comprises:

and drying the thallium-containing high-fluorine chlorine smoke dust to constant weight at 60-90 ℃ and grinding to 100-400 meshes.

9. The method of claim 1, further comprising smelting the baked good.

10. Use of a method according to any one of claims 1 to 9 for the selective separation of thallium from thallium-containing high fluorine chlorine fumes.