CN113332756B - Calcium sulfide-based slow-release vulcanizing agent and preparation method and application thereof - Google Patents

Abstract

The invention discloses calcium sulfide-based slow-release sulfurAgent, preparation method and application thereof. Uniformly mixing molten paraffin, zeolite particles and calcium sulfide particles, carrying out mold-assisted cooling molding to obtain solid particles, spraying a coating liquid containing ethyl cellulose and stearic acid on the surface of the solid particles, and volatilizing a solvent at room temperature to obtain the calcium sulfide-based slow-release vulcanizing agent. The calcium sulfide-based slow-release vulcanizing agent can stably and slowly release heavy metal ions precipitated deeply during vulcanization in an acid solution system, has high vulcanizing agent utilization rate, and can avoid H₂The escape of S causes secondary pollution, is particularly suitable for purifying heavy metal ions in an acid solution, and the calcium sulfide-based slow-release vulcanizing agent has simple and efficient preparation process and low raw material cost, and is beneficial to large-scale production and application.

Description

A calcium sulfide-based slow-release vulcanizing agent and its preparation method and application

technical field

The invention relates to a slow-release vulcanizing agent, in particular to a calcium sulfide-based slow-release vulcanizing agent, a preparation method of the calcium sulfide-based slow-releasing vulcanizing agent, and heavy metal ions of the calcium sulfide-based slow-releasing vulcanizing agent in an acidic solution system The application of sulfide precipitation belongs to the technical field of non-ferrous metal smelting.

Background technique

In 2019, China's top ten non-ferrous metals such as copper, aluminum, lead, zinc, nickel, antimony, and magnesium had a production capacity of 58.416 million tons, ranking first in the world in non-ferrous metal production. At the same time, a large amount of acidic wastewater (that is, polluted acid) containing toxic heavy metal ions such as arsenic, copper, cadmium, and zinc will be produced in the non-ferrous metal smelting process. Wastewater containing heavy non-ferrous metals and their compounds can accumulate and accumulate in aquatic organisms and plant cells, and circulate in the food chain through bioconcentration, bioaccumulation, biomagnification, etc. serious health hazards. Non-ferrous metal smelting polluted acid is mainly produced from flue gas recovery and electrolytic leaching phase. Due to the high content of arsenic and heavy metals and high residual acid in polluted acid, a lot of research has been done on the disposal of polluted acid in China.

Common sewage acid treatment methods in modern non-ferrous metal smelters include chemical method (including lime neutralization method, chemical flocculation method, sulfide precipitation method), physical method (including membrane separation method, adsorption method), biological method, etc. The above single method is difficult to meet the current environmental protection requirements, and now it is mostly a combination of two methods, such as lime neutralization-iron salt method, lime neutralization-sulfurization method, etc.

The sulfurization method can convert heavy metal ions in polluted acid into sulfides to achieve high-efficiency separation of heavy metals, and has been widely used. In the prior art, Na ₂ S and NaHS are commonly used as vulcanizing agents, and the existing technical problem is that it is easy to release a large amount of H ₂ S gas, causing secondary pollution, and the sodium salt (Na ₂ SO ₄ ) contained in the backwater after the vulcanization treatment is in the The heat transfer wall is easy to scab to form Glauber's salt (Na ₂ SO ₄ ·10H ₂ O), which increases the equipment load and deteriorates the working conditions. Chai Liyuan et al. used H ₂ S gas as a vulcanizing agent and invented a gas-liquid enhanced vulcanization technology. The problem is that the vulcanizing agent H ₂ S gas of this technology needs to be acidified by metal sulfide concentrated acid in advance (such as the reaction of pyrite and hydrochloric acid). It is very dangerous and difficult to operate, and in order to obtain better vulcanization effect, a special gas _- liquid reactor needs to be customized, and the equipment investment cost is high. In order to make full use of the abundant calcium and sulfur resources in gypsum slag, it has been reported that calcium sulfide prepared by reduction of gypsum slag is used as a vulcanizing agent for foul acid treatment, but calcium sulfide as a vulcanizing agent has a fast reaction rate and low H ₂ S gas utilization. , some of the H ₂ S gas escapes and causes secondary pollution and other problems.

SUMMARY OF THE INVENTION

In view of the problems in the prior art that calcium sulfide is used as a vulcanizing agent in the process of purifying polluted acid heavy metal ions by a vulcanization method, the release rate of sulfur anion is not easy to control, the utilization rate of the vulcanizing agent is low, and the escape of part of the H ₂ S gas causes secondary pollution and the like. The first purpose is to provide a kind of calcium sulfide that can realize slow-release sulfur anion under acidic conditions and can realize deep purification of heavy metal ions of foul acid, which is obtained by coating and modifying active material calcium sulfide with zeolite and paraffin. Based on slow-release vulcanizing agent, the calcium sulfide-based slow-release vulcanizing agent has low cost, controllable release rate of sulfur anion, can improve the utilization rate of calcium sulfide resources, reduce environmental pollution caused by hydrogen sulfide escape, and is economically feasible and green. Development, suitable for large-scale industrial promotion.

The second object of the present invention is to provide a preparation method of a calcium sulfide-based slow-release vulcanizing agent, which is low in cost, simple in operation, and conducive to large-scale production.

The third object of the present invention is to provide the application of a calcium sulfide-based slow-release vulcanizing agent in the sulfide precipitation of heavy metal ions in an acidic solution system. The utilization rate of the vulcanizing agent is improved, and the deep purification of heavy metal ions can be realized, and the pollution of the environment caused by the escape of hydrogen sulfide is reduced, which is conducive to large-scale popularization and application.

In order to achieve the above technical purpose, the present invention provides a preparation method of a calcium sulfide-based slow-release vulcanizing agent. The method is to uniformly mix molten paraffin, zeolite particles and calcium sulfide particles, and then assisted cooling and molding through a mold to obtain solid particulate matter. , after spraying the coating liquid containing ethyl cellulose and stearic acid on the surface of the solid particles, and volatilizing the solvent at room temperature to obtain.

When traditional calcium sulfide is used as a vulcanizing agent, its reactivity is high, and there is a "slow release and burst release", that is, the release rate in the early stage of investment is relatively fast, and the utilization rate of the vulcanizing agent is low, resulting in waste of resources and environmental pollution. After that, it can completely isolate the calcium sulfide active component from contacting with the acidic solution system to form a "slow release coating", that is, the calcium sulfide active component is over-coated and cannot release sulfide ions. The key point of the technical solution of the present invention is to use paraffin and zeolite particles to synergistically modify calcium sulfide. On the basis of paraffin-coated calcium sulfide, an appropriate amount of zeolite particles are mixed into the paraffin coating layer. The zeolite particles have stable structure and acid resistance. It has a porous structure on the surface, which can be used as an effective channel for liquid and sulfur anion. The acidic solution can react with the calcium sulfide active ingredient inside the calcium sulfide-based slow-release vulcanizing agent through the pores of the zeolite, and the generated sulfur anion can pass through the pores of the zeolite. Escape carries out vulcanization reaction on heavy metal ions entering into the acid solution system to achieve the purpose of slow release vulcanization.

As a preferred solution, the mass ratio of molten paraffin, zeolite particles and calcium sulfide particles is (1-3):(2-4):(3-7). The most preferred mass ratio of molten paraffin, zeolite particles and calcium sulfide particles is 1.5:3:5.5. Paraffin wax is mainly used to coat the active substance of calcium sulfide particles, which can effectively isolate the contact reaction between calcium sulfide and acidic solution. The purpose of introducing zeolite particles is to change the structure of the paraffin coating layer, and use the porous structure of zeolite particles to form paraffin wax. It is an effective channel for the calcium sulfide active component inside the coating layer to contact the acidic solution. The acidic solution can enter the slow-release agent through the pore structure of the zeolite, and react with the calcium sulfide inside the slow-release agent, thereby causing the internal and external solutions of the slow-release agent. The concentration difference of sulfide ions promotes the release of sulfide ions inside the slow-release agent into the acidic solution system under the action of the concentration gradient. Therefore, by controlling the dosage ratio of zeolite particles and paraffin to calcium sulfide, the release rate of sulfide anions from the slow-release agent into the acidic solution can be regulated. The amount of paraffin added affects the thickness of the coating layer on the surface of calcium sulfide particles. When the proportion of paraffin added is too high, such as accounting for more than 30% of the mass of the slow-release agent, the surface of calcium sulfide is uniformly and completely coated with paraffin layer. The release amount of calcium sulfide is small and the release is slow, and when the proportion of paraffin added is moderate, such as the addition ratio accounts for 10% to 20% of the mass of the slow-release agent, the slow-release agent is well formed, and there are a small amount of cracks or active components on the surface of the slow-release agent ( Calcium sulfide), which can be continuously released and released completely, but when the proportion of paraffin added is too low, such as less than 6% of the mass of the slow-release agent, due to the low paraffin content, the particles are not tightly bonded, and it is difficult to form, and the early stage When the release rate is relatively large, the phenomenon of "sustained release and burst release" occurs. The addition amount of zeolite particles mainly affects the contact reaction area between the acidic solution and calcium sulfide. . Therefore, by controlling the paraffin, zeolite particles and calcium sulfide particles within the preferred ratio range, the calcium sulfide-based slow-release vulcanizing agent can achieve a better effect of slow-releasing sulfur anion.

As a preferred solution, the molten paraffin, zeolite particles and calcium sulfide particles are uniformly mixed by mechanical stirring, the stirring speed is 100r/min～180r/min, and the stirring time is 15min～25min. By controlling the mechanical stirring conditions, the molten paraffin can be uniformly mixed with the zeolite particles and the calcium sulfide particles, which is beneficial to the formation of a uniform coating structure. The most preferred stirring speed is 150r/min, and the most preferred stirring time is 20min.

As a preferred solution, in the coating liquid, the mass of ethyl cellulose accounts for 8% to 10% of the mass of the calcium sulfide-based slow-release vulcanizing agent; 3% to 5%. The main raw material of calcium sulfide slow-release agent, calcium sulfide, is easy to be oxidized in the air and easy to be hydrolyzed in humid air. It should be sealed and moisture-proof during storage. Therefore, in the technical solution of the present invention, the surface of the slow-release vulcanizing agent is sprayed with a coating liquid (ie, a coating agent) to solve the above-mentioned technical problems. The main components in the coating liquid are ethyl cellulose and stearic acid. Ethyl cellulose is an organic substance with the properties of binding, filling and film-forming, which can be used as a coating for sustained-release pellets, while stearic acid is a A surface active substance that forms a homogeneous and stable emulsion when mixed with ethyl cellulose. The amount of ethyl cellulose and stearic acid added is calculated according to 8% to 10% and 3% to 5% of the mass of the calcium sulfide-based slow-release vulcanizing agent, respectively. If a high proportion of ethyl cellulose is added, the cost will increase, and excessive Encapsulating calcium sulfide sustained-release agent results in a slow release rate in the early stage, and the coating liquid with too low a proportion of ethyl cellulose has poor coverage, and the surface of the sustained-release agent can still be in contact with air. However, the amount of stearic acid added as a surfactant is small, excessive addition will form micelles and flocs, and too little addition will be difficult to form an emulsion, resulting in poor spraying effect. The solvent in the coating solution is an organic solvent capable of dissolving ethyl cellulose and stearic acid and volatile at room temperature. The preferred organic solvent is an alcoholic solvent, such as ethanol, glycerol, etc. The amount of the solvent is not limited, as long as the ethyl cellulose and stearic acid are fully dissolved, which can be understood by those skilled in the art .

As a preferred solution, the mass ratio of stearic acid and ethyl cellulose is (0.5-1):(2-3). The mass ratio of stearic acid and ethylcellulose is most preferably 1:2.5.

As a preferred solution, the paraffin is melted at a temperature of 60°C to 80°C.

The mold involved in the present invention is a conventional mold, and the mold is mainly used for cooling and forming of paraffin, so that the mixture of molten paraffin, zeolite particles and calcium sulfide particles is cooled to form solid particulate material.

The present invention also provides a calcium sulfide-based slow-release vulcanizing agent obtained by the preparation method.

As a preferred solution, it is applied to the sulfide precipitation of heavy metal ions in an acidic solution system.

As a preferred solution, the temperature condition of the sulfide precipitation is 30°C to 50°C.

As a preferred solution, the dosage of the calcium sulfide-based slow-release vulcanizing agent is 1.1 to 1.5 times the theoretical molar amount of the calcium sulfide-based slow-release vulcanizing agent required to generate the corresponding sulfide from heavy metal ions in the acidic solution system.

As a preferred solution, the acidic solution system is at least one of dirty acid, zinc leaching solution, copper leaching solution, industrial waste acid and electrolyte.

Relative to the prior art, the beneficial technical effects brought by the technical solution of the present invention:

The calcium sulfide-based sustained-release vulcanizing agent provided by the invention has the advantages of stable sustained-release process and good sustained-release effect in an acidic solution system, can improve the utilization rate of the vulcanizing agent, and can avoid secondary pollution caused by the generation of H ₂ S, especially It is suitable for purifying heavy metal ions in acidic solutions.

The preparation method of the calcium sulfide-based slow-release vulcanizing agent provided by the invention adopts calcium sulfide, zeolite and paraffin as raw materials, has low cost, and has a simple and efficient preparation process, which is favorable for large-scale production.

The calcium sulfide-based slow-release vulcanizing agent provided by the invention is applied to the sulfide precipitation of heavy metal ions in an acidic solution system, which can not only deeply remove the heavy metal ions in the acidic solution system, but also has high utilization rate of the vulcanizing agent and avoids the harmful gas of hydrogen sulfide. It is easy to operate, and the process is controllable, which meets the requirements of industrial applications.

Description of drawings

Fig. 1 is the process flow diagram of the present invention to prepare calcium sulfide-based slow-release vulcanizing agent.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

The arsenic concentration of a lead and zinc smelter in Hunan is 2g/L, the zinc ion concentration is 0.7g/L, the lead ion concentration is 100mg/L, and the copper ion concentration is 60mg/L.

First, the paraffin was melted at 70°C, then calcium sulfide and zeolite were added according to the mass ratio of paraffin, zeolite and calcium sulfide at 1.5:3:5.5, stirred for 20 min, and poured into a mold for condensation. Ethyl cellulose and stearic acid were fully dissolved in a small amount of ethanol according to the mass percentages of 8% and 3%, respectively, to prepare a uniform coating solution. The coating liquid is uniformly sprayed on the surface of the solid particles after condensation to obtain a calcium sulfide slow-release agent. The calcium sulfide slow-release agent was added to the acidic solution, and the added calcium sulfide slow-release agent was 1.1 times the theoretical amount. The reaction was stirred for 40 minutes, and the reaction temperature was controlled at 45 °C. After the reaction, a flocculant was added to accelerate the sedimentation, and finally solid-liquid separation was carried out. It can be seen from Table 1 that the arsenic precipitation rate can reach 97.65%, the zinc ion precipitation rate can reach 92.71%, the lead ion precipitation rate can reach 92%, and the copper ion precipitation rate can reach 93.3%.

Table 1: Main components and ion precipitation rate of the lead-zinc smelter sewage acid purification filtrate of Example 1 (paraffin: zeolite: calcium sulfide = 1.5:3:5.5)

name A_S Zn²⁺ Pb²⁺ Cu²⁺ Concentration/mg/L 47 51 8 4.02 Precipitation rate/% 97.65 92.71 92.00 93.33

Comparative Example 1

The source of foul acid is the same as in Example 1, except that no zeolite is added. By comparing Tables 1 and 2, it is found that the vulcanization effect of the calcium sulfide slow-release agent without zeolite is significantly lower than that of Example 1, and the waste of calcium sulfide resources is large.

Table 2: The main components and ion precipitation rate of the lead-zinc smelter sewage acid purification filtrate of Comparative Example 1 (without adding zeolite)

name AS Zn²⁺ Pb²⁺ Cu²⁺ Concentration/mg/L 656.8 242.2 68.9 16.7 Precipitation rate/% 67.16 65.40 68.90 72.17

Comparative Example 2

The source of fouling acid is the same as that in Example 1, except that ethyl cellulose is not added in the coating liquid. By comparing Tables 1 and 3, it is found that the calcium sulfide slow-release agent without ethyl cellulose is vulcanized in the coating liquid. The effect is obviously lower than that of Example 1, and most of the calcium sulfide in the slow-release agent is hydrolyzed or oxidatively deteriorated.

Table 3: The main components and ion precipitation rate of the lead-zinc smelter sewage acid purification filtrate of Comparative Example 2 (without adding ethyl cellulose)

name AS Zn²⁺ Pb²⁺ Cu²⁺ Concentration/mg/L 1593.2 559.02 75.00 43.68 Precipitation rate/% 23.04 20.14 25.00 27.20

Example 2

In a zinc smelter in Hunan, the arsenic concentration was 30.3 mg/L, the zinc ion concentration was 450 mg/L, the cadmium ion concentration was 30.6 mg/L, and the copper ion concentration was 4.7 mg/L.

first. The paraffin was melted at 70°C, then calcium sulfide and zeolite were added according to the mass ratio of paraffin, zeolite and calcium sulfide at 1.5:3.5:5, stirred for 20 min, and poured into a mold for condensation. In addition, ethyl cellulose and stearic acid were fully dissolved in ethanol according to the mass percentages of 10% and 4%, respectively, to prepare a uniform coating solution. The coating liquid is uniformly sprayed on the surface of the solid particles after condensation to obtain a calcium sulfide slow-release agent. The calcium sulfide slow-release agent was added to the foul acid, and the added calcium sulfide slow-release agent was 1.15 times the theoretical dosage. The reaction was stirred for 40 minutes, and the reaction temperature was controlled at 40 °C. After the reaction, a flocculant was added to accelerate the sedimentation, and finally the solid-liquid separation was carried out. From Table 4, it can be seen that the zinc ion precipitation rate can reach 93.78%, the arsenic ion precipitation rate can reach 92.82%, the cadmium ion precipitation rate can reach 93.20%, and the copper ion precipitation rate can reach 95.74%.

Table 4: Main components and ion precipitation rate of the sewage acid purification filtrate of the zinc smelter of Example 2 (paraffin: zeolite: calcium sulfide = 1.5:3.5:5)

name As Zn²⁺ Cd²⁺ Cu²⁺ Concentration/mg/L 2.18 27.99 2.08 0.20 Precipitation rate/% 92.81 93.78 93.20 95.74

Comparative Example 3

The source of foul acid in Comparative Example 3 was the same as that in Example 2, except that no zeolite was added. By comparing Tables 4 and 5, it is found that the sulfide precipitation rate of the calcium sulfide slow-release agent without the addition of zeolite is significantly lower than that of Example 2 of the present invention, and the calcium sulfide resource waste is large, which is not suitable for industrial application.

Table 5: The main components and ion precipitation rate of the sewage acid purification filtrate of the zinc smelter of Comparative Example 3 (without adding zeolite)

name As Zn²⁺ Cd²⁺ Cu²⁺ Concentration/mg/L 10.36 159.75 10.12 1.54 Precipitation rate/% 65.81 64.50 66.92 67.23

Comparative Example 4

The source of fouling acid is the same as in Example 2, the difference is that ethyl cellulose is not added in the coating liquid. By comparing Table 4 and Table 6, it is found that the calcium sulfide slow-release agent without ethyl cellulose is vulcanized in the coating liquid. The effect is obviously lower than that of Example 2, and most of the calcium sulfide in the slow-release agent is hydrolyzed or deteriorated by oxidation.

Table 6: The main components and ion precipitation rate of the lead-zinc smelter sewage acid purification filtrate of Comparative Example 4 (without adding ethyl cellulose)

Example 3

In a zinc smelter in Hunan, the arsenic concentration was 45.3 mg/L, the zinc ion concentration was 330 mg/L, the lead ion concentration was 22 mg/L, and the copper ion concentration was 8.0 mg/L.

first. The paraffin was melted at 70°C, then calcium sulfide and zeolite were added according to the mass ratio of paraffin, zeolite and calcium sulfide at 1:3:6, stirred for 25 minutes, and poured into a mold for condensation. In addition, ethyl cellulose and stearic acid were fully dissolved in ethanol according to the mass percentages of 10% and 4%, respectively, to prepare a uniform coating solution. The coating liquid is uniformly sprayed on the surface of the solid particles after condensation to obtain a calcium sulfide slow-release agent. The calcium sulfide slow-release agent was added to the foul acid, and the added calcium sulfide slow-release agent was 1.2 times the theoretical amount. The reaction was stirred for 45 minutes, and the reaction temperature was controlled at 40 °C. After the reaction, a flocculant was added to accelerate the sedimentation, and finally the solid-liquid separation was carried out. It can be seen from Table 7 that the zinc ion precipitation rate can reach 95.20%, the arsenic precipitation rate can reach 93.50%, the lead ion precipitation rate can reach 95.00%, and the copper ion precipitation rate can reach 97.40%.

Table 7: The main components and ion precipitation rate of the filtrate of sewage acid purification filtrate from the zinc smelter of Example 3 (paraffin: zeolite: calcium sulfide = 1:3:6)

name AS Zn²⁺ Pb²⁺ Cu²⁺ Concentration/mg/L 2.95 15.84 1.21 0.21 Precipitation rate/% 93.50 95.20 95.00 97.40

The above is only the preferred embodiment of the application, and does not limit the application in any form. Although the application is disclosed as above with the preferred embodiment, it is not intended to limit the application. Without departing from the scope of the technical solutions of the present application, any changes or modifications made by using the technical contents disclosed above are equivalent to equivalent implementation cases and fall within the scope of the technical solutions.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, and substitutions can be made in these embodiments without departing from the principle and spirit of the invention and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (10)

1. A preparation method of calcium sulfide-based slow-release vulcanizing agent is characterized by comprising the following steps: uniformly mixing molten paraffin, zeolite particles and calcium sulfide particles, carrying out cooling molding with the assistance of a mold to obtain solid particles, spraying a coating liquid containing ethyl cellulose and stearic acid on the surfaces of the solid particles, and volatilizing a solvent at room temperature to obtain the catalyst.

2. The method for preparing a calcium sulfide-based slow-release vulcanizing agent according to claim 1, wherein the calcium sulfide-based slow-release vulcanizing agent comprises the following steps: the mass ratio of the molten paraffin, the zeolite particles and the calcium sulfide particles is (1-3) to (2-4) to (3-7).

3. The method for preparing a calcium sulfide-based slow-release vulcanizing agent according to claim 1, wherein the calcium sulfide-based slow-release vulcanizing agent comprises the following steps: the molten paraffin, the zeolite particles and the calcium sulfide particles are uniformly mixed by adopting a mechanical stirring mode, the stirring speed is 100 r/min-180 r/min, and the stirring time is 15 min-25 min.

4. The method for preparing the calcium sulfide-based slow-release vulcanizing agent according to claim 1, characterized in that: the mass of the ethyl cellulose in the coating liquid accounts for 8-10% of the mass of the calcium sulfide-based slow-release vulcanizing agent, and the mass of the stearic acid accounts for 3-5% of the mass of the calcium sulfide-based slow-release vulcanizing agent; the solvent in the coating liquid is an organic solvent which can dissolve the ethyl cellulose and the stearic acid and is volatile at room temperature.

5. The method for preparing a calcium sulfide-based slow-release vulcanizing agent according to claim 1 or 4, wherein: the mass ratio of stearic acid to ethyl cellulose is (0.5-1) to (2-3).

6. A calcium sulfide-based slow-release vulcanizing agent is characterized in that: the preparation method of any one of claims 1 to 5.

7. The use of a calcium sulfide-based slow-release vulcanizing agent according to claim 6, wherein: the method is applied to the sulfide precipitation of heavy metal ions in an acid solution system.

8. The use of a calcium sulfide-based slow-release vulcanizing agent according to claim 7, wherein: the temperature condition of the sulfuration precipitation is 30-50 ℃.

9. The use of a calcium sulfide-based slow-release vulcanizing agent according to claim 7, wherein: the dosage of the calcium sulfide-based slow-release vulcanizing agent is 1.1-1.5 times of the theoretical molar quantity of the calcium sulfide-based slow-release vulcanizing agent required for generating corresponding sulfides by heavy metal ions in an acidic solution system.

10. The use of a calcium sulfide-based slow-release vulcanizing agent according to claim 7, wherein: the acidic solution system is at least one of waste acid, zinc leachate, copper leachate, industrial waste acid and electrolyte.

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