JP2007070708A - Wet type treating method for zinc leach residue - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve, in a wet type treating process for zinc residue, the dehydrating property of gypsum produced in a first stage neutralization step, to improve productivity in this step, and to improve the quality of the resultant gypsum. <P>SOLUTION: The zinc leach residue is leached, and the resultant leachate is put into a first stage neutralization reaction vessel to undergo neutralization by the addition of a neutralizing agent and then separated into a first overflow and a first underflow, and the first overflow is fed to a subsequent step and the first underflow is separated into first stage gypsum and a filtrate. In the above step, the first underflow and/or the filtrate is returned to the first stage neutralization reaction vessel. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In order to recover the zinc remaining in the zinc leaching residue separated in the zinc leaching process of wet zinc smelting, the present invention removes mainly iron as hematite from the zinc leaching residue and returns to the zinc leaching process. In particular, the present invention relates to a processing method that increases the efficiency of the neutralization step in the hematite process.

  The raw ore of wet zinc smelting usually contains 1 to 12% iron, and forms zinc ferrite corresponding to iron in a roasting furnace. Since zinc ferrite is insoluble under normal sinter (roasted ore) leaching conditions, zinc leaching residue is removed together with other components other than zinc when leaching zinc in wet zinc smelting.

  The zinc leaching residue is mixed with various other elements including zinc, iron, and valuable metals that could not be leached. Therefore, in order to recover the zinc still remaining in the zinc leaching residue, this processed material (liquid) is processed after removing and recovering iron and other valuable metals other than zinc from the zinc leaching residue. Is returned to the zinc leaching process of zinc smelting.

  As a method for recovering zinc from the zinc leaching residue (zinc ferrite) and separating and removing iron, a so-called hematite process, which takes the chemical name of the generated iron residue, has been put into practical use. For example, Patent Document 1 discloses a wet treatment method for zinc leaching residue that separates and recovers hematite generated when the zinc residue treatment of wet zinc smelting is performed in a hematite process. Therefore, the processing method will be briefly described with reference to the drawings.

FIG. 3 is a flowchart showing an outline of an example of a hematite process according to the prior art. In the hematite process, the zinc leaching residue removed as a solid content when leaching sinter by wet zinc smelting and solid-liquid separation is applied to the secondary leaching step (1) and the one-step neutralization step (2 ), Arsenic removal step (3), two-step neutralization step (4), and iron removal step (5), and after the removal of the iron removal solution in the leaching step of zinc smelting It is a process that performs processing. Here, hematite is a substance represented by a chemical formula of Fe ₂ O ₃ .

(1) Secondary leaching step In this step, the zinc leaching residue obtained by wet zinc smelting is added to the above zinc smelting electrolytic tail liquor to form a pulp and then leached in a reducing atmosphere such as SO ₂ to solidify ( S) Liquid (L) The liquid is separated into a solid containing lead and silver as main components and a leachate containing other components.

(2) One-step neutralization step In this step, a neutralizing agent (for example, calcium carbonate) is added to the leachate obtained in the leaching step, and the free sulfuric acid in the leachate is neutralized and solid-liquid separated. Is a step of separating into a liquid containing a solid component and other components.

(3) De-arsenic process This process involves adding zinc powder to the neutralized solution obtained in the above-mentioned one-step neutralization process for solid-liquid separation, and as an RT residue that is a solid content mainly containing copper and arsenic. It is the process of isolate | separating from the liquid containing these components.

(4) Two-stage neutralization step This step involves solid-liquid separation by increasing the pH while adding a neutralizing agent (for example, calcium carbonate) to the solution after separating copper arsenide in the above-mentioned dearsenic step, and mainly using aluminum. This is a step of separating into a solid content of a trivalent cation compound as a component and a liquid containing other components.

(5) Deironing process In this process, the liquid after separation of aluminum and the like in the two-stage neutralization process is hydrolyzed while oxidizing iron in the hematite generation temperature region, and then solid separated to contain iron as hematite. This is a step of separating into a solid and a liquid containing zinc.

JP 2002-30355 A

  In the above-described one-step neutralization step, neutralization is performed with a neutralizing agent (for example, calcium carbonate) until the amount of free acid in the leachate obtained in the secondary leaching step is 5 to 8 g / l. This is because Fe in the secondary leaching solution is efficiently recovered as high-quality iron oxide in the iron removal step, which is a subsequent step. However, since the particle size of the gypsum produced in the neutralization is fine, the dehydrating property of the gypsum is deteriorated, the productivity is lowered, and the quality of the obtained gypsum is lowered.

Furthermore, in order to remove trivalent cations such as aluminum, which is an impurity for the iron removal process, neutralization is performed again with a neutralizing agent (for example, calcium carbonate) after the first stage neutralization to adjust the pH to 4. ˜5, a two-stage neutralization step is performed in which the trivalent cation is precipitated and removed as a hydroxide. Here, when calcium carbonate is used as an inexpensive neutralizing agent, the trivalent cation hydroxide and gypsum are produced to form a slurry. This slurry is separated by a filter, but the amount of generated residue is large, and the capacity of the post-process must be increased. However, even if Mg (OH) ₂ or NaOH is used as a neutralizing agent, these neutralizing agents are expensive and are used as impurities or the combined product adversely affects the smelting process. It was difficult.

  The present invention has been made against the background described above, and one of the problems to be solved is to improve the dehydration property of gypsum produced in the one-step neutralization step and increase the productivity of the step. At the same time, it is to improve the quality of the obtained gypsum. Another problem to be solved by the present invention is to increase the separation of trivalent cation and gypsum from the slurry of trivalent cation hydroxide and gypsum produced in the two-stage neutralization step. Thus, it is to increase the recovery efficiency of useful metals in the trivalent cation while reducing the equipment burden in the subsequent process.

In order to solve the above-mentioned problems, it has been found that the growth process of the neutralized product during the neutralization reaction can be controlled by adding the neutralized product generated after neutralization to the original neutralization tank.
The first means is
It is a wet processing method of zinc leaching residue obtained by wet zinc smelting,
The zinc leaching residue is leached, the obtained leachate is put into a first stage neutralization reaction tank, a neutralizing agent is added, and it is separated into a first overflow and a first underflow. Is sent to the next process and the first underflow is separated into gypsum and filtrate.
The first underflow is classified, and the fine-grained gypsum after classification is repeated in the first stage neutralization reaction tank.

The second means is
It is a wet processing method of zinc leaching residue obtained by wet zinc smelting,
The zinc leaching residue was leached, the obtained leachate was put into a first-stage neutralization reaction tank, a neutralizing agent was added, and the first overflow and the first underflow were separated. 1 overflow into the second stage neutralization reactor, neutralizing agent is added to separate the second overflow and the second underflow, and the resulting second underflow is supplied to the second stage. It is the wet processing method of the zinc leaching residue characterized by repeating to the neutralization reaction tank.

The third means is
It is a wet processing method of zinc leaching residue obtained by wet zinc smelting,
The zinc leaching residue was leached, the obtained leachate was put into a first-stage neutralization reaction tank, a neutralizing agent was added, and the first overflow and the first underflow were separated. In the step of charging 1 overflow into the second stage neutralization reaction tank, adding a neutralizing agent, and separating into a second overflow and a second underflow,
Wet classifier leaching residue, characterized in that a wet classifier is used to separate the second overflow and the second underflow, and the obtained second underflow is repeated in the first stage neutralization reactor. It is a processing method.

The fourth means is
A wet processing method for zinc leaching residue, which is performed in combination with the wet processing methods described in the first and third means.

The fifth means is
A wet processing method for zinc leaching residue, which is performed by using the wet processing methods described in the first, second and third means.

The sixth means is
5. The wet processing method for zinc leaching residue according to any one of the first to fourth means, wherein calcium carbonate is used as a neutralizing agent.

  According to the first or third means, a first-stage gypsum having a large particle size and good dewaterability was produced, and the productivity of the process was improved, and at the same time, a good-quality first-stage gypsum could be obtained.

  According to the 2nd means, the particle size of the gypsum became large and the separability of the 2nd underflow and the 2nd overflow improved.

  According to the fourth means, a single-stage gypsum having a large particle size and good dehydrating properties is produced, and the productivity of the process can be improved. A second underflow composed mainly of good gypsum was produced, and the quality of the solid concentrate containing trivalent cations was improved in the second overflow.

  According to the 5th means, the cost of the process was able to be reduced by using an inexpensive raw material called calcium carbonate as a neutralizing agent.

Hereinafter, embodiments of the present invention will be described with reference to the drawings and tables.
FIG. 1 is a flow diagram of an example of a hematite process according to the present invention.
The zinc concentrate 1 becomes a zinc sinter through the roasting process 2, and zinc is mainly separated and recovered in the primary leaching process 3 and sent to the liquid purification process 4 and the electrolysis process 5. On the other hand, the zinc residue 6 after the zinc is recovered contains various components from zinc ore and auxiliary materials. Examples of the components are shown in Table 1. As is apparent from Table 1, the zinc residue 6 contains gold, silver, copper, lead, iron, zinc, and cadmium as components. Two examples of composition of zinc residue 6 are listed in Table 1.

In the hematite process, iron in the zinc residue 6 is fixed and removed as iron oxide, and the remaining zinc content is returned to the main system of zinc smelting.
First, the zinc residue 6 is subjected to a secondary leaching step 7 using sulfuric acid and SO ₂ gas, and iron or the like is leached into the secondary leaching solution 9 as Fe ^{2+ and the} like, and solid-liquid separation is performed. For example, lead, silver or the like is separated as a solid lead residue 8 as a solid content. Two examples of the composition of the secondary leachate 9 are listed in Table 2.

The step of neutralizing the free sulfuric acid in the secondary leachate 9 with the neutralizing agent 10 to make the concentration of the free sulfuric acid 5-8 g / l and removing the remaining free sulfuric acid as the first-stage gypsum 17 is in one stage. It is a sum process.
(In the present invention, in order to distinguish a plurality of processes having the same name, the first, second, etc. are identified for convenience. However, the identification method and expression are not particularly limited.)
First, preferable neutralizing agent 10 includes calcium carbonate and quicklime. The addition of the neutralizing agent 10 is preferably performed while stirring the secondary leachate 9 accommodated in the first stage neutralization reaction tank 11. Note that the number of addition ports for the neutralizing agent 10 and the appropriate position of the first-stage neutralization reaction tank 11 with respect to the stirrer are appropriately determined depending on the liquid amount, tank pressure, stirring speed, and the like. After the completion of neutralization, the liquid in the first stage neutralization reaction tank 11 is sent to the thickener 12, and the first o / f (overflow) 15 is sent to the next dearsenation process 18, where the first The u / f (underflow) 19 is dehydrated using the centrifuge 13 to obtain a liquid 16 containing particles mainly composed of fine gypsum and a first-stage gypsum 17. Two examples of the composition of the first-stage gypsum 17 are shown in Table 3.

  In the present embodiment, the liquid 16 containing particles mainly composed of fine gypsum obtained from the first u / f 19 using the centrifuge 13 is fed into the first stage neutralization reaction tank 11. The structure is repeated. The filtrate 16 contains a gypsum content (the gypsum content may be referred to as repetitive gypsum), and the repetitive gypsum is re-introduced into the first stage neutralization reaction tank 11, thereby In the one-stage neutralization reaction tank 11, it becomes a growth point (core) of newly precipitated gypsum, and the particle size of the gypsum can be increased. Here, the particle size of the repeated gypsum is preferably fine and uniform, and the gypsum formed into needle-like crystals is preferably repeated. The median diameter of gypsum is in the range of 140 to 170 μm, but it is preferable to repeatedly use gypsum on the fine grain side of about 150 μm or less. Therefore, classification is performed with a centrifuge.

Here, by repeatedly charging the gypsum into the first-stage neutralization reaction tank 11, the particle size of the newly-deposited first-stage gypsum 17 in the first-stage neutralization reaction tank 11 is increased. What can be done will be further described with reference to Table 4 and FIG.
Table 4 is a table showing the ratio of the particle size, specific surface area, and particles having a particle size of 5 μm or less for three samples of the first-stage gypsum 17. FIG. 2 is a graph in which the vertical axis represents the distribution ratio and the horizontal axis represents the particle size, and the particle size distribution for three samples in the first-stage gypsum 17 is plotted. As is clear from the results of Table 4 and FIG. 2, all the three samples of the first-stage gypsum 17 produced have a particle size of 1000 μm or less, and are in the range of 100 to 300 μm and are homogeneous. On the other hand, the proportion of particles having a particle size of 5 μm or less, which can cause a decrease in productivity in the filtration step, is less than 2% in any sample. Therefore, the produced first-stage gypsum 17 contributed to improving the productivity of the filtration process, and also excellent in dehydrating properties, which also contributed to improving the productivity.
The particle size and particle size distribution can be measured using a commercially available sieve or a laser diffraction type particle size distribution measuring machine.

On the other hand, the first o / f 15 sent to the arsenic removal process 18 is stored in the second stage neutralization reaction tank 21 after the RT residue (copper arsenide) 20 is removed in the arsenic removal process 18. A Ca-based neutralizer 22 is added to carry out a two-step neutralization reaction. The neutralization reaction is preferably performed while stirring the first o / f15 as in the case of the above-described one-stage neutralization. Note that the number of addition ports for the neutralizing agent 22 and the appropriate position of the second-stage neutralization reaction tank 21 with respect to the stirrer are appropriately determined depending on the liquid amount, tank pressure, stirring speed, and the like. Moreover, as a preferable neutralizing agent 22, calcium carbonate and quicklime are mentioned. An example of the composition of the product produced by the two-stage neutralization reaction is shown in Table 5.

  The product generated by the two-stage neutralization reaction is classified by the classification thickener 23 (or hydraulic classification), the second o / f27 containing a hydroxide-based precipitate, and the first-stage neutralization A gypsum concentrated slurry 26 that is the second u / f to be repeated into the reaction vessel 11 is obtained. Here, for the classification, a wet classifier is preferably used, and gypsum can be efficiently separated by using a classification thickener (or hydraulic classification).

The obtained gypsum concentrated slurry 26 is repeated to the second stage neutralization reaction tank 21. Here, the particle size of the gypsum concentrated slurry 26 is preferably fine and uniform, and it is preferable to re-inject the gypsum that has become needle-like crystals. The median diameter of gypsum is in the range of 10 to 200 μm, but it is preferable to use a gypsum on the fine grain side of about 150 μm or less for recharging. Therefore, classification may be further performed. Here, composition examples of the gypsum concentrated slurry 26 are shown in Table 6.

The gypsum concentrated slurry 26 is re-introduced into the second-stage neutralization reaction tank 21 to become a growth point (core) of gypsum newly precipitated in the second-stage neutralization reaction tank 21, Increase the particle size of gypsum.
In addition, it is also preferable to take the structure which repeats the gypsum concentration slurry 26 to the neutralization reaction tank 11 of the 1st stage. By adopting this configuration, it is possible to further increase the particle size and dewaterability of the first-stage gypsum described above.
Of course, it is also preferable to use a combination of the configuration in which the gypsum concentrated slurry 26 is repeated in the second-stage neutralization reaction tank 21 and the configuration in which the gypsum-concentrated slurry 26 is repeated in the first-stage neutralization reaction tank 11.

On the other hand, the second o / f 27 is subjected to solid-liquid separation by the filter press 28, and the solid content is recovered as a solid concentrate containing a trivalent cation such as Al. At this time, since most of the gypsum has already been removed by the classification thickener 23, the second o / f 27 is solid-liquid separated by the filter press 28 with high efficiency.
The filtrate 29 of the filter press 28 is sent to a deironing step 30 where hematite (iron oxide) 31 is separated, and then becomes a deironed post-solution 32 which is repeated to the primary leaching step 3 and the like. Table 7 shows a composition example of the solid concentrate 33 containing trivalent ions such as Al, In, and Ga.

  When comparing the results shown in Tables 6 and 7, most of the trivalent cations such as Al migrate to the solid concentrate 33 containing trivalent cations such as Al, and most of the gypsum It turned out that it moved to the gypsum concentrated slurry 26. That is, the recycle gypsum is re-introduced into the second-stage neutralization reaction tank 21, thereby containing valuable metals such as In, Ga, etc. while using a simple, easy and highly productive separation means of classification. Extraction of valuable metals from the solid concentrate 33 containing trivalent cations as well as the separation of the solid concentrate containing trivalent cations from the gypsum content is sufficiently performed and the productivity in the separation process is improved. It has become clear that it can also contribute greatly to the productivity of.

It is a flowchart of one example of the hematite process which concerns on this invention. It is the graph which plotted the particle size distribution of the 1 step | paragraph gypsum sample which concerns on this invention. It is a flowchart of an example of the hematite process which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Zinc concentrate 2 Roasting process 3 Primary leaching process 4 Purification process 5 Electrolysis process 6 Zinc residue 7 Secondary leaching process 8 Lead silver residue 9 Secondary leaching solution 10 Neutralizing agent 11 First stage neutralization reaction Tank 12 Thickener 13 Centrifuge 14 First u / f
15 First o / f
16 Filtrate 17 First stage gypsum 18 Dearsenic process 19 First u / f
21 Second stage neutralization reactor 22 Neutralizing agent 23 Classification thickener 26 Gypsum concentrated slurry 27 Second o / f
28 Filter press 29 Filtrate 30 Deironing process 32 Deironed post-solution 33 Solid concentrate

Claims (6)

It is a wet processing method of zinc leaching residue obtained by wet zinc smelting,
The zinc leaching residue is leached, the obtained leachate is put into a first stage neutralization reaction tank, a neutralizing agent is added, and the first overflow and the first underflow are separated. Overflow is sent to the next process, and the first underflow is the process of separating gypsum and filtrate,
A wet treatment method for zinc leaching residue, characterized by classifying the first underflow and repeating the classified fine-gypsum side gypsum to the first stage neutralization reaction tank. It is a wet processing method of zinc leaching residue obtained by wet zinc smelting,
The zinc leaching residue was leached, the obtained leachate was put into a first-stage neutralization reaction tank, a neutralizing agent was added, and the first overflow and the first underflow were separated. 1 overflow into the second stage neutralization reactor, neutralizing agent is added to separate the second overflow and the second underflow, and the resulting second underflow is supplied to the second stage. A wet processing method for zinc leaching residue, which is repeated in a neutralization reaction tank. It is a wet processing method of zinc leaching residue obtained by wet zinc smelting,
The zinc leaching residue was leached, the obtained leachate was put into a first-stage neutralization reaction tank, a neutralizing agent was added, and the first overflow and the first underflow were separated. In the step of charging 1 overflow into the second stage neutralization reaction tank, adding a neutralizing agent, and separating into a second overflow and a second underflow,
Wet classifier leaching residue characterized in that a wet classifier is used to separate the second overflow and the second underflow, and the obtained second underflow is repeated to the first stage neutralization reaction tank. Processing method.   A wet processing method for zinc leaching residue, wherein the wet processing method according to claim 1 and 3 is used in combination.   A wet processing method for a zinc leaching residue, wherein the wet processing method according to claim 1, 2 and 3 is used in combination. 6. The wet treatment method for zinc leaching residue according to any one of claims 1 to 5, wherein calcium carbonate is used as a neutralizing agent.

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