CN115595446B - A method for ultrasonically enhanced potassium dichromate oxidation leaching of zinc oxide dust - Google Patents

Abstract

The invention discloses a method for oxidizing and leaching zinc oxide smoke dust by using ultrasonic reinforced potassium dichromate, belonging to the technical field of hydrometallurgy and comprehensive utilization of resources. The method for oxidizing and leaching zinc oxide smoke dust by using ultrasonic reinforced potassium dichromate comprises the following steps: mixing zinc oxide smoke dust and potassium dichromate, adding sulfuric acid solution to prepare a reaction solution, and then placing the reaction solution under the conditions of ultrasonic wave and stirring to perform oxidation leaching of the zinc oxide smoke dust. The method for leaching zinc and germanium in zinc oxide smoke dust has the advantages of high leaching rate, short leaching time and the like, overcomes the defect that silica colloid and iron colloid adsorb and precipitate zinc and germanium in other processes, reduces acid consumption, can highly enrich lead in the smoke dust and return lead for smelting and use, and has obvious economic benefit.

Description

A method for ultrasonically enhanced potassium dichromate oxidation leaching of zinc oxide dust

Technical Field

The invention relates to the technical field of hydrometallurgy and comprehensive resource utilization, in particular to a method for ultrasonically enhanced potassium dichromate oxidation leaching of zinc oxide smoke.

Background Art

Zinc and germanium are widely used in important fields such as battery manufacturing and national defense. Lead-zinc ore is the main ore deposit associated with germanium. In the process of zinc smelting, the mineral is roasted-neutral leaching-fuming volatilization to obtain by-product zinc oxide dust. In this process, germanium compounds are almost not dissolved, so that the content of zinc and germanium in zinc oxide dust after enrichment is greater than 50wt.% and 500g/t respectively. However, with the development of science and technology and the improvement of people's living standards, the demand for zinc and germanium at home and abroad is increasing, which makes the amount of zinc leaching slag continue to increase, and also leads to the increasing scarcity of resources. If secondary resources such as zinc leaching slag are not rationally utilized, the accumulation of by-products will not only cause environmental pollution, but also cause serious waste of resources. Therefore, it is of great significance to effectively leach zinc and germanium from zinc oxide dust.

At present, industrial production usually adopts two-stage acid leaching to treat zinc and germanium in germanium-containing zinc oxide dust. Industrial production results show that under this process condition, the leaching rate of zinc and germanium is usually 90% and 80%. The reasons for the low leaching rate of this process are: (1) Zinc oxide dust usually contains a large amount of sphalerite, galena and other substances that are difficult to dissolve in acid. These substances will not only wrap the germanium-containing compounds, but also replace each other with germanium in the crystal lattice. (2) Under low-acid conditions, long-term leaching will not only reduce production efficiency, but also cause the trivalent iron and silicate in the leachate to hydrolyze, thereby adsorbing and precipitating valuable metals such as zinc and germanium.

Summary of the invention

The purpose of the present invention is to provide a method for ultrasonically enhanced potassium dichromate oxidation leaching of zinc oxide dust to solve the problems existing in the prior art. The present invention uses potassium dichromate as an oxidant and sulfuric acid as a solvent, and aims to provide a method for efficiently and economically leaching zinc and germanium from germanium-containing zinc oxide dust. The method not only significantly improves the leaching rate of zinc and germanium, but also reduces the amount of leached slag, so that lead compounds can be enriched and comprehensively utilized, meeting the requirements of resource utilization and slag reduction.

To achieve the above object, the present invention provides the following solutions:

One of the technical solutions of the present invention is a method for ultrasonic enhanced potassium dichromate oxidation leaching of zinc oxide smoke, comprising the following steps:

The zinc oxide fume and potassium dichromate are mixed and then added with sulfuric acid solution to prepare a reaction solution, and then the reaction solution is placed under ultrasonic and stirring conditions to oxidize and leach the zinc oxide fume.

The specific reactions are as follows:

ZnS+Fe ³⁺ =Zn ² ++Fe ²⁺ +S ⁰ ;

The main substance in zinc oxide dust is zinc oxide. In addition to zinc oxide, zinc also exists in the form of zinc sulfide. Similarly, lead and germanium also exist in the form of sulfide. Sulfide is not dissolved in the presence of only sulfuric acid. At the same time, according to characterization, germanide in zinc oxide dust will not only be enriched in the sphalerite lattice (zinc sulfide), but will also be wrapped by sulfide, hindering the leaching of germanium. Therefore, the introduction of potassium dichromate as an oxidant can promote the conversion of sulfide into sulfate, thereby achieving the dissolution of sulfide.

Under the action of ultrasound and sulfuric acid, the insoluble sulfides can be reacted, and the insoluble zinc sulfide can be converted into soluble zinc sulfate, and the germanium compounds wrapped in the smoke can be exposed. Compared with oxidants such as ozone and hydrogen peroxide, potassium dichromate will not cause corrosion to the equipment, and will not decompose due to factors such as temperature, resulting in a large consumption of additives and increasing production costs. The addition of potassium dichromate can effectively oxidize sphalerite and other insoluble zinc-containing compounds into soluble substances. At the same time, potassium dichromate has a fast oxidation reaction rate as an oxidant, which can significantly overcome the problem of iron ions and silicate hydrolysis-coprecipitation taking away a large amount of valuable metals, so that the leaching rates of zinc and germanium exceed 99% and 90% respectively.

Furthermore, before preparing the reaction solution, the method also includes drying and sieving the zinc oxide fume to obtain pretreated zinc oxide fume.

Furthermore, the drying is vacuum drying, and the vacuum degree is 0.005-0.01 MPa; the drying temperature is 60° C., and the drying time is 24 hours; and the sieve mesh number used in the screening is 80-200 meshes.

Furthermore, the volume/mass ratio of the sulfuric acid solution to the zinc oxide fume is 6 to 8 mL/g.

Furthermore, the mass/volume ratio of the potassium dichromate to the sulfuric acid solution is 4.5-33.82 g:1L.

Furthermore, the concentration of the sulfuric acid solution is 120-200 g/L.

Furthermore, the power of the ultrasonic wave is 90-600W, the frequency is 19.5kHz, and the current is 0.31A; and the stirring speed is 50-300r/min.

Furthermore, the oxidation leaching temperature is 40 to 90° C., and the time is 30 to 180 minutes.

Furthermore, the main components of the zinc oxide fume include zinc-containing compounds and germanium-containing compounds.

Furthermore, the zinc-containing compound includes zinc oxide, zinc sulfide and zinc sulfate; the germanium-containing compound includes germanium monoxide, germanium dioxide, germanate and its sulfide.

The present invention discloses the following technical effects:

(1) The reaction rate of the present invention is fast, the operation is simple, and there is no danger. Under the action of ultrasound, the interior of the solution is violently vibrated, reducing the viscosity of the reaction system and the mass transfer resistance between the solid and the liquid. In addition, the action of ultrasound causes a large number of microbubbles to be generated inside the solution. As the bubbles grow and burst, the energy in the bubbles is released, causing microjets and shock waves to be generated in the solid-liquid phase, weakening the thickness of the diffusion layer at the solid-liquid interface and continuously eroding to produce a new reaction interface, allowing the reaction to continue. The added potassium dichromate continuously reacts with substances such as sulfides at the new interface, exposing the lattice-substituted and encapsulated germanide to the acid system, thereby increasing the leaching rates of zinc and germanium to more than 99% and 90%, respectively, and controlling the slag rate to about 30%.

(2) The present invention achieves the goal of improving the leaching rate of zinc and germanium by optimizing various influencing parameters, thereby achieving the purpose of comprehensive utilization and harmless treatment of resources.

(3) The method of the present invention is used to leach zinc and germanium from zinc oxide dust, which has the advantages of high leaching rate and short leaching time, and overcomes the disadvantages of other processes that the leaching time is long, resulting in the adsorption and precipitation of zinc and germanium by colloidal silica and iron colloid. At the same time, the acid consumption is reduced, the lead in the dust can be highly enriched and returned to lead smelting for utilization, and has obvious economic benefits.

BRIEF DESCRIPTION OF THE DRAWINGS

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

FIG1 is a process flow chart of Example 1 of the present invention;

FIG2 is an XRD diagram of zinc oxide smoke (raw material) in Example 1 of the present invention;

FIG3 is an XRD diagram of the filter residue obtained after oxidative leaching in Example 1 of the present invention;

FIG4 is a graph showing the effect of leaching time on the leaching rate of zinc and germanium;

Figure 5 is a graph showing the effect of leaching time on the leaching rates of lead, iron, silicon and aluminum.

DETAILED DESCRIPTION

Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and materials related to the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

The zinc oxide soot treated in the following embodiments and comparative examples of the present invention is germanium-containing zinc oxide soot, and its main components are zinc-containing compounds and germanium-containing compounds; the zinc-containing compounds are zinc oxide, zinc sulfide and zinc sulfate, etc.; the germanium-containing compounds are germanium monoxide, germanium dioxide, germanate and its sulfide, etc., and the main chemical components are shown in Table 1. The values in Table 1 are ICP-OES quantitative analysis values.

Table 1 Main chemical components of germanium-containing zinc oxide dust

Ge (g/t) indicates the number of grams of Ge contained in each ton of germanium-containing zinc oxide dust.

The zinc oxide smoke used in the following examples and comparative examples of the present invention is subjected to vacuum drying treatment, the vacuum degree of the vacuum drying treatment is 0.005-0.01 MPa, the drying temperature is 60° C., and the drying time is 24 h.

The following examples and comparative examples of the present invention use Cu-Kα as the X-ray light source, λ=0.15416nm, voltage ≤40KV, current ≤40mA, and an X-ray diffractometer (XRD) (D8ADVANCE) for phase analysis.

Example 1

A method for ultrasonically enhancing potassium dichromate oxidation leaching of zinc oxide dust:

(1) Pass zinc oxide dust through a 200-mesh sieve, then weigh 40 g of the sieved zinc oxide dust (raw material), weigh 6.31 g of potassium dichromate, and measure 280 mL of sulfuric acid solution (concentration: 140 g/L).

(2) zinc oxide fume and potassium dichromate are mixed and placed in a reactor, and then sulfuric acid solution is added and mixed to obtain a reaction solution (the volume/mass ratio of sulfuric acid solution to zinc oxide fume in the reaction solution is 7 mL:1 g, that is, the liquid-to-solid ratio is 7 mL/g, and the concentration of potassium dichromate in the reaction solution is 22.54 g/L, that is, the mass/volume ratio of potassium dichromate to sulfuric acid solution is 22.54 g/L, that is, 6.31 g:280 mL). Under a constant temperature of 90° C., The ultrasonic power is 500W, the frequency is 19.5kHz, the current is 0.31A, and the stirring speed is 150r/min. The oxidation leaching is carried out for 30min. After the leaching is completed, the solid-liquid separation is carried out, and the solid is washed with 25mL of deionized water (the washing liquid is used as part of the filtrate) to obtain a filter residue and a filtrate; the filter residue is dried at 60°C for 15h to obtain a dry-base filter residue with a mass of 11.81g; after the filtrate is impurity-free, tannin germanium is precipitated, and then zinc electrolysis is carried out. The specific flow chart is shown in Figure 1, the XRD diagram of zinc oxide smoke is shown in Figure 2, and the XRD diagram of the filter residue is shown in Figure 3.

Comparative Example 1

The same as Example 1, except that ultrasonic treatment is not performed, specifically: the zinc oxide fume and potassium dichromate are mixed and placed in a reactor, and then a sulfuric acid solution is added. Under a constant temperature of 90° C., the stirring speed is controlled to be 150 r/min, and oxidative leaching is performed. The leaching time is 30 min. After the leaching is completed, solid-liquid separation is performed, and the solid is washed with 25 mL of deionized water (the washing liquid is used as part of the filtrate) to obtain a filter residue and a filtrate; the filter residue is dried at 60° C. for 15 h to obtain a dry filter residue with a mass of 13.61 g.

Comparative Example 2

The same as comparative example 1, except that the leaching time is 120 min, and filter residue and filtrate are obtained; the filter residue is dried at 60° C. for 15 h to obtain a dry-base filter residue with a mass of 13.93 g.

Effect Example 1

The contents of zinc and germanium in the filtrates of Example 1 and Comparative Examples 1-2 were determined, and the leaching rates were calculated. The results are shown in Table 2.

CP-OES quantitative analysis shows that the zinc content in zinc oxide dust is 53.3wt.%, and the germanium content is 510.10g/t, that is, 40g of dust contains 21.32g of zinc and 20.4mg of germanium.

The formula for calculating the zinc leaching rate is as follows:

Wherein μ is the zinc leaching rate, x is the zinc concentration in the filtrate, v is the volume of the filtrate, w is the zinc content in the zinc oxide fume, and m is the mass of the added zinc oxide fume.

The formula for calculating the leaching rate of germanium is as follows:

Wherein μ is the leaching rate of germanium, x is the germanium concentration in the filtrate, v is the volume of the filtrate, w is the germanium content in the zinc oxide fume, and m is the mass of the added zinc oxide fume.

Table 2

It can be seen from Table 2 that without ultrasonic treatment (Comparative Example 1 and Comparative Example 2), the leaching rates of zinc and germanium decreased, while extending the leaching time can increase the leaching rate.

Example 2

(1) Pass zinc oxide dust through a 200-mesh sieve, then weigh 40 g of the sieved zinc oxide dust (raw material), weigh 6.31 g of potassium dichromate, and measure 120 mL of sulfuric acid solution (concentration: 140 g/L).

(2) zinc oxide fume and potassium dichromate are mixed and placed in a reactor, and then sulfuric acid solution is added and mixed to obtain a reaction solution (liquid-to-solid ratio is 3 mL/g, and the concentration of potassium dichromate is 22.54 g/L). Under a constant temperature of 90° C., the ultrasonic power is controlled to be 300 W, the frequency is 19.5 kHz, the current is 0.31 A, and the stirring speed is 150 r/min. Oxidative leaching is performed for 30 min. After the leaching is completed, solid-liquid separation is performed, and the solid is washed with 25 mL of deionized water (the washing liquid is used as part of the filtrate) to obtain a filter residue and a filtrate; the filter residue is dried at 60° C. for 15 h to obtain a dry filter residue.

Example 3

Same as Example 2, except that the amount of sulfuric acid solution used is 160 mL (liquid-to-solid ratio is 4 mL/g).

Example 4

Same as Example 2, except that the amount of sulfuric acid solution used is 200 mL (liquid-to-solid ratio is 5 mL/g).

Example 5

Same as Example 2, except that the amount of sulfuric acid solution used is 240 mL (liquid-to-solid ratio is 6 mL/g).

Example 6

Same as Example 2, except that the amount of sulfuric acid solution used is 280 mL (liquid-to-solid ratio is 7 mL/g).

Example 7

The same as Example 2, except that the amount of sulfuric acid solution used is 320 mL (liquid-to-solid ratio is 8 mL/g).

Effect Example 2

The contents of zinc and germanium in the filtrates of Examples 2 to 7 and the mass of the dry residue were determined, and the leaching rates were calculated (the calculation method was the same as that of Effect Example 1). The results are shown in Table 3.

Table 3

As can be seen from Table 3, during the leaching process, the liquid-solid ratio has a crucial effect on the leaching rate of germanium. When the liquid-solid ratio is between 7 and 8 mL/g, the germanium leaching rate is high. When the liquid-solid ratio is lower than 3 mL/g, the germanium leaching rate is low. The main reason is that the amount of sulfuric acid added is small, so the reaction cannot be fully carried out. In addition, when the liquid-solid ratio is lower than 7 mL/g (the larger the liquid-solid ratio, the lower the viscosity), the viscosity of the reaction system is large, the diffusion resistance between the solid and the liquid increases, and the reaction interface between the metal compound and the sulfuric acid is slowly updated. When the leaching rate is higher than 7 mL/g, the leaching rates of zinc and germanium do not change much. Therefore, from an economic point of view, it is most appropriate to take a liquid-solid ratio of 7 mL/g.

Example 8

(1) Pass zinc oxide dust through a 200-mesh sieve, then weigh 40 g of the sieved zinc oxide dust (raw material), weigh 6.31 g of potassium dichromate, and measure 280 mL of sulfuric acid solution (concentration: 120 g/L).

(2) zinc oxide fume and potassium dichromate are mixed and placed in a reactor, and then sulfuric acid solution is added and mixed to obtain a reaction solution (liquid-to-solid ratio is 7 mL/g, potassium dichromate concentration is 22.54 g/L), and under a constant temperature of 80° C., ultrasonic power is controlled to be 300 W, frequency is 19.5 kHz, current is 0.31 A, and stirring speed is 150 r/min to perform oxidation leaching. The leaching time is 30 min. After the leaching is completed, solid-liquid separation is performed, and the solid is washed with 25 mL of deionized water (the washing liquid is used as part of the filtrate) to obtain a filter residue and a filtrate; the filter residue is dried at 60° C. for 15 h to obtain a dry filter residue.

Embodiment 9

Same as Example 8, except that the concentration of the sulfuric acid solution is 140 g/L.

Example 10

Same as Example 8, except that the concentration of the sulfuric acid solution is 160 g/L.

Embodiment 11

Same as Example 8, except that the concentration of the sulfuric acid solution is 180 g/L.

Example 12

Same as Example 8, except that the concentration of the sulfuric acid solution is 200 g/L.

Comparative Example 3

Same as Example 11, except that potassium dichromate is replaced with an equal mass of ferric sulfate.

The Fe ³⁺ in ferric sulfate plays an oxidizing role.

Comparative Example 4

Same as Example 11, except that potassium dichromate is replaced with an equal mass of sodium nitrate.

The sodium nitrate in sodium nitrate is oxidizing and has an oxidizing effect.

Comparative Example 5

The same as Example 11, except that potassium dichromate is replaced with an equal mass of sodium nitrate and the oxidation leaching time is adjusted to 60 min.

Effect Example 3

The contents of zinc and germanium in the filtrates of Examples 8 to 12 and Comparative Examples 3 to 5 and the mass of the dry residue were determined, and the leaching rates were calculated (the calculation method was the same as that of Effect Example 1). The results are shown in Table 4.

Table 4

As can be seen from Table 4, the reason why the leaching rate is reduced by extending the leaching time of Comparative Example 4 compared with Comparative Example 5 is that the reaction time is extended, and some substances in the oxidizing smoke (such as silicate, aluminum-containing compound, iron-containing compound, etc.) will gradually react and enter the solution, so that the pH of the system increases. In the reaction process, the hydrolysis of substances such as silicate is a dynamic process. When the pH is greater than 2 or less than 2, the silicate will be hydrolyzed. Therefore, at the beginning of the leaching reaction, as the silicate is dissolved in the sulfuric acid solution, the hydrolysis of the silicate will occur. Therefore, the leaching rate of zinc and germanium (increase or decrease) depends on the adsorption amount of the colloid formed by the silicate and the dissolution amount of zinc and germanium. That is, at the beginning of the leaching reaction, only a small amount of silicate is hydrolyzed, and the adsorption amount of the colloidal silica is small at this time, and the dissolution amount of zinc and germanium is very large, so the leaching rate of zinc and germanium is on the rise. After zinc and germanium are leached out in large quantities, the remaining zinc and germanium can only be gradually dissolved at a slow rate. At this time, more silicates are also dissolved in sulfuric acid, producing more colloidal silica, which makes the adsorption amount larger, that is, greater than the dissolution amount of zinc and germanium, so the leaching rate of zinc and germanium shows a downward trend.

Example 13

(1) Pass zinc oxide dust through a 200-mesh sieve, then weigh 40 g of the sieved zinc oxide dust (raw material), weigh 1.26 g of potassium dichromate, and measure 280 mL of sulfuric acid solution (concentration: 120 g/L).

(2) zinc oxide fume and potassium dichromate are mixed and placed in a reactor, and then sulfuric acid solution is added and mixed to obtain a reaction solution (liquid-to-solid ratio is 7 mL/g, potassium dichromate concentration is 4.5 g/L), and under a constant temperature of 80° C., ultrasonic power is controlled to be 300 W, frequency is 19.5 kHz, current is 0.31 A, and stirring speed is 150 r/min to perform oxidation leaching. The leaching time is 30 min. After the leaching is completed, solid-liquid separation is performed, and the solid is washed with 25 mL of deionized water (the washing liquid is used as part of the filtrate) to obtain a filter residue and a filtrate; the filter residue is dried at 60° C. for 15 h to obtain a dry filter residue.

Embodiment 14

(1) Pass zinc oxide fume through a 200-mesh sieve, then weigh 40 g of the sieved zinc oxide fume (raw material), weigh 9.47 g of potassium dichromate, and measure 280 mL of sulfuric acid solution (concentration: 120 g/L).

(2) zinc oxide fume and potassium dichromate are mixed and placed in a reactor, and then sulfuric acid solution is added and mixed to obtain a reaction solution (liquid-to-solid ratio is 7 mL/g, potassium dichromate concentration is 33.82 g/L), and under a constant temperature of 90° C., ultrasonic power is controlled to be 200 W, frequency is 19.5 kHz, current is 0.31 A, and stirring speed is 150 r/min to perform oxidation leaching. The leaching time is 30 min. After the leaching is completed, solid-liquid separation is performed, and the solid is washed with 25 mL of deionized water (the washing liquid is used as part of the filtrate) to obtain a filter residue and a filtrate; the filter residue is dried at 60° C. for 15 h to obtain a dry filter residue.

Embodiment 15

(1) Pass zinc oxide dust through a 200-mesh sieve, then weigh 40 g of the sieved zinc oxide dust (raw material), weigh 6.31 g of potassium dichromate, and measure 280 mL of sulfuric acid solution (concentration: 140 g/L).

(2) zinc oxide fume and potassium dichromate are mixed and placed in a reactor, and then sulfuric acid solution is added and mixed to obtain a reaction solution (liquid-to-solid ratio is 7 mL/g, potassium dichromate concentration is 22.54 g/L), and under a constant temperature of 90° C., ultrasonic power is controlled to be 500 W, frequency is 19.5 kHz, current is 0.31 A, and stirring speed is 150 r/min to perform oxidative leaching for 180 min. After leaching, solid-liquid separation is performed, and the solid is washed with 25 mL of deionized water (the washing liquid is used as part of the filtrate) to obtain a filter residue and a filtrate; the filter residue is dried at 60° C. for 15 h to obtain a dry filter residue.

Example 16

(1) Pass zinc oxide dust through a 200-mesh sieve, then weigh 40 g of the sieved zinc oxide dust (raw material), weigh 6.31 g of potassium dichromate, and measure 280 mL of sulfuric acid solution (concentration: 140 g/L).

(2) zinc oxide fume and potassium dichromate are mixed and placed in a reactor, and then sulfuric acid solution is added and mixed to obtain a reaction solution (liquid-to-solid ratio is 7 mL/g, potassium dichromate concentration is 22.54 g/L), and under a constant temperature of 60° C., ultrasonic power is controlled to be 300 W, frequency is 19.5 kHz, current is 0.31 A, and stirring speed is 150 r/min to perform oxidation leaching. The leaching time is 30 min. After the leaching is completed, solid-liquid separation is performed, and the solid is washed with 25 mL of deionized water (the washing liquid is used as part of the filtrate) to obtain a filter residue and a filtrate; the filter residue is dried at 60° C. for 15 h to obtain a dry filter residue.

Effect Example 4

The contents of zinc and germanium in the filtrates of Examples 13 to 16 and the mass of the dry residue were determined, and the leaching rates were calculated (the calculation method was the same as that of Effect Example 1). The results are shown in Table 5.

Table 5

Compared with Comparative Example 2, Example 13 has a lower initial acid sulfuric acid concentration, a lower reaction temperature and a lower oxidant concentration, so the effect of Example 13 is far inferior to that of Comparative Example 2.

Compared with Comparative Example 2, Example 14 has a low sulfuric acid concentration. During the leaching process, the acid concentration plays a decisive role in the leaching rate, and the effect of ultrasound is smaller than that of sulfuric acid.

Compared with Comparative Example 2, Example 15 has a longer reaction time. According to our research, adding ultrasound can increase the leaching rate by 2-5%. However, the longer leaching time makes the colloid produced by the hydrolysis of silicate and Fe ³⁺ absorb a large amount of dissolved zinc and germanium. The negative effect of adsorption is much greater than the positive effect of ultrasound, so the leaching rate of Example 15 is much lower than that of Comparative Example 2.

Compared with Comparative Example 2, Example 16 has a lower reaction temperature. The low temperature reduces the movement rate of various substances in the reaction system, slows down the mass transfer rate, and reduces the probability of collision between molecules, resulting in a decrease in the reaction rate. Therefore, the leaching rate of Example 16 is slightly lower than that of Comparative Example 2.

Effect Example 5

The experimental parameters with a leaching time of 30 minutes are the same as those in Example 1. Only the leaching time is changed, and the other parameters are the same as those in Example 1. A leaching effect diagram (zinc and germanium) varying with the leaching time is obtained, and the results are shown in FIG4 .

FIG4 is a graph showing the effect of leaching time on the leaching rate of zinc and germanium;

The test parameters for the leaching time of 30 min are the same as those in Example 1. Only the leaching time is changed, and the other parameters are the same as those in Example 1. A leaching effect diagram (lead, iron, silicon and aluminum) varying with the leaching time is obtained. The results are shown in Figure 5.

According to the effect of reaction time on the leaching rate of zinc and germanium (Figure 4), it can be found that with the extension of reaction time, the leaching of zinc first shows a platform trend, and then shows a decreasing trend after 60 minutes, while the leaching rate of germanium shows a decreasing trend as a whole. Combined with the reaction time to the reaction diagram of iron and silicon (Figure 5), it is mainly because the long-term leaching causes some substances (such as silicates) in the zinc oxide fume to react slowly, causing the pH in the liquid to increase, reaching the pH at which silicon and iron (especially silicon) hydrolyze. At 60 minutes, the iron content in the solution began to decrease, and at 90 minutes, the silicon content in the solution decreased, all because of the hydrolysis.

The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims (5)

1. The method for oxidizing and leaching zinc oxide smoke dust by using ultrasonic reinforced potassium dichromate is characterized by comprising the following steps of: mixing zinc oxide smoke dust and potassium dichromate, adding sulfuric acid solution to prepare a reaction solution, and then placing the reaction solution under the conditions of ultrasonic wave and stirring to perform oxidation leaching of the zinc oxide smoke dust;

The volume/mass ratio of the sulfuric acid solution to the zinc oxide smoke dust is 7mL/g;

The mass/volume ratio of the potassium dichromate to the sulfuric acid solution is 22.54g:1L;

The concentration of the sulfuric acid solution is 140g/L;

The power of the ultrasonic wave is 500W, the frequency is 19.5kHz, and the current is 0.31A; the stirring speed is 150r/min;

the temperature of the oxidation leaching is 90 ℃ and the time is 30min.

2. The method for oxidizing and leaching zinc oxide fume by using ultrasonic enhanced potassium dichromate according to claim 1, wherein the method further comprises the steps of drying and screening the zinc oxide fume before preparing the reaction solution to obtain pretreated zinc oxide fume.

3. The method for oxidizing and leaching zinc oxide fume by using the ultrasonic enhanced potassium dichromate according to claim 2, wherein the drying is vacuum drying, and the vacuum degree is 0.005-0.01 MPa; the drying temperature is 60 ℃ and the drying time is 24 hours; the mesh number of the sieves adopted by the screening is 80-200 meshes.

4. The method for oxidation leaching of zinc oxide soot using ultrasonic wave to intensify potassium dichromate according to claim 1, wherein the main components of the zinc oxide soot include zinc-containing compounds and germanium-containing compounds.

5. The method of oxidizing leaching of zinc oxide fumes of claim 4, wherein the zinc-containing compound comprises zinc oxide, zinc sulfide, and zinc sulfate; the germanium-containing compounds include germanium monoxide, germanium dioxide, germanates and sulfides thereof.