JPS61261446A - Method for recovering zn from zn containing material - Google Patents

Abstract

PURPOSE:To recover Zn having high purity at a low cost by rinsing away water soluble impurities from a Zn-contg. material contg. Fe, Pb, Cl, etc., then extracting the Zn-component therefrom by sulfuric acid, adjusting the pH thereof, removing Fe and heavy metals from the material, adding Zn powder and sulfuric acid to the material and subjecting the same to a Pb removal treatment then to a carbonization treatment. CONSTITUTION:The slurry subjected to rinsing away of the water soluble impurities from the above-mentioned Zn-contg. material is subjected gradually to sulfuric acid dropping at about 3.5+ or -0.2pH to extract the Zn-component. An Na2CO3 soln. of 1-3% concn. is then added to the Zn extraction liquid to adjust the pH to 4-5 and an oxidizing agent such as H2O2 is added thereto to oxidize Fe<2+> to Fe3+ and to settle and separate Fe as Fe(OH)3 and other heavy metals. Sulfuric acid is added to the extraction liquid of the settling and separating treatment to adjust the pH to about 2-3. The Zn powder is added to such liquid and the formed Pb is filtered out by an ion exchange. The Na2CO3 of 2-5% concn. is added to the filtrate and the filtrate is subjected to the carbonization treatment at 6.7-7.2pH to recover Zn as the basic zinc carbonate.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is used in steel plants to recover waste from kiln dust containing impurities such as Fe5Pb1α generated from reduced pellet plants or dust from blast furnaces. It's about how to do it.

[Prior art]

Various methods have already been proposed for recovering K from Zn-containing materials generated in steel works, such as the above-mentioned kiln dust, blast furnace dust, converter dust, and waste liquid sludge from Zn plating. There is. For example, as a wet method,
Method 4 involves dissolving and separating, and Method 2 involves contacting the contained material with Rodan waste liquid and recovering it as Roda 7'Zx+. However, as a dry method, a reducing agent such as coke is added to the K-containing material and the residue is recovered by reducing and volatilizing the K-containing material.
In this case as well, it is difficult to remove a because it is reduced and volatilized, and the purity of the recovered Zn is low.

[Problem that the invention seeks to solve]

The present invention addresses the above-mentioned problems when recovering K from materials containing Fe, Pb, and especially those generated from reduced pellet factories.
This was discovered as a result of various experimental studies with the aim of recovering blood with higher purity than dust containing impurities such as α at a lower cost. Sulfuric acid is added to the slurry from which water-soluble impurities have been removed to extract the Zn component, and after adjusting the pH to 4-5 by adding soda carbonate, an oxidizing agent is added to remove Fe and F.
After removing Fe, blood powder and sulfuric acid are added to the extract to remove it, and the resulting solution is carbonated to make it basic. Recovering as zinc carbonate, returning the filter cake separated by filtration for the sludge removal process to the Zn extraction process, adding sodium carbonate to the extracted zinc sulfate solution, washing with water, and recovering as basic zinc carbonate. ,
It is characterized in that the supernatant liquid is recycled and used as water for washing the Zn-containing material.

[Means and actions for solving problems]

The present invention will be described in detail with reference to the accompanying process diagrams.

Add water and repeat the process of washing with water → standing → draining several times with a washing time of 20 minutes/time to remove water-soluble impurities α, 1'4.
The supernatant water containing K, etc. is treated as wastewater. This washing water is 7tr
? If the amount is too low, sedimentation will be slow, less supernatant water will be discharged, and more impurities will remain.

The slurry after washing with water is mixed by gradually adding sulfuric acid (H2SO4) dropwise at a pH of about 8.5 ± 0.2 without causing large pH variations under pHM observation, and then mixed with the following (1).
) is extracted by the reaction of formula.

Zn + H2SO4−+ ZnSO4+ H2・=(
11 In this case, if the pH is 3 or less, the solubility of Fe increases, which is not preferable.

It is economical to add the filtered cake after removing atom, which will be described later, to the water-washed slurry in the extraction step.

Add a sodium carbonate (Na2CO3) solution with a concentration of 1 to 3 to the extract using H2SO4 and adjust the pH to 4 to 5.
By adding an oxidizing agent such as hydrogen peroxide (H2O2), the following (
2) Oxidize Fe by the reaction of the formula.

In this case, when the Na2CO3 concentration increases beyond 3.
Ni, Mn, etc. are carbonated and mixed into the product as impurities, which is undesirable. In addition, in order to remove Fe according to the above formula (2), the pH is set to 4 or higher, and it is precipitated and separated as ferric hydroxide.If I)H is made higher than 5, Fe is precipitated as zinc hydroxide and removed. Because of this, the yield decreases.

H and other heavy metals are precipitated according to the above formula (2), and filtered using a filter such as a filter press. The filtered cake is returned to the reduction Beret factory for collection, and H2SO4 is added to the p-filtered extract to raise the pH ~ 3, and add mu powder (obtained by cooling zinc vapor by distillation method, also called blue powder, a mixture of metal + oxidized mu powder) which has a greater ionization tendency than 9, and make the following ( 3) Cause ion exchange according to the formula.

Pb + Zn −+ Pb + Zn” − (3)
Bottle Precipitation In this case, H2SO4 is added to lower the pH to 2 to 3 because the H removal effect and the economical effect of the Zn powder cannot be obtained unless the powder is made into an acidic state and then reduced to a reduced state.

It is also possible to use zinc oxide or k lump as a substitute for k powder.

9 is precipitated as a metal by the reaction of formula (3) above,
In the case of the wire Fe, solid-liquid separation is performed using a filter press in the same manner as above, and since K still remains in the filter cake, it is returned to the above-mentioned mu extraction step, and the 10-20 concentration is removed from impurities by p filtration extraction. of zinc sulfate (Zn5O4) solution,
Add 2-5% Na2CO3 solution and adjust the pH to 6,7.
~7.2, at a temperature of 10 to 65°C, Zn5O, a + Na2
cO3+4H2α+2ZnCOs ・3Zn((E)2
%Ω+3CO2+5NazSO4−-・”(41(4)
React according to the formula.

In this case, if the ZnSO4 concentration is increased, more impurities will be mixed in during the reaction of formula (4), and if the Na2CO3 concentration is increased above 5%, Ni, Mn, etc. will be carbonated and mixed into the product as impurities. Furthermore, if the pH is increased beyond 7.2, impurities will be present and the purity of the product will be poor, while if the pH is below 6.7, the yield will be significantly reduced. CO in Na2CO3 solution
2 gases may be added supplementarily.

Since SO4 ions and Na 2 So 4 remain in the solution after the reaction according to the above formula (4) is completed, washing with water → standing → draining is repeated several times to remove the above impurities and convert the basic carbonic acid into Zinc is produced, and the supernatant water is reused as washing water in the washing process for Zn-containing materials.

The basic zinc carbonate produced as described above is purified to Zn by a commonly employed known method.

[Experimental examples and effects]

Next, an experimental example of kiln dust containing Fe, PB, C1, etc. will be explained.

(1) Water washing process: kiln dust (Zn-containing material), water amount ratio "/49)"
It was washed with water under the following conditions: 3 times in water and 20 minutes in washing time.

Table 1 shows the analysis results before and after washing with water. Before and after washing with water, Na
1, a removal rate of 90% or more was obtained for C1.

(21Znn oil extraction process H2SO4 dropping rate and extraction liquid to slurry after washing,
The analysis results of the residue are shown in Table 2. As is clear from the same table, the amount of H2SO4 dropped is limited to about 95% of the Zn equivalent.
As shown in Table 2, it is not advisable to use more than that because impurities such as Fe will dissolve. Therefore, it is understood that the pH should be set at 3.5±0.2 as the end point.

Table 2 (3) R removal (contains trace amounts of heavy metals) step To the extract of (2) above, add a NazCO3 solution with a concentration of 1 to 3,
By dropping an oxidizing agent such as H2O2 after adjusting the pH to 4 to 5, Fe can be removed as well as trace amounts of heavy metals.

Table 3 shows the results of removing Fe and trace heavy metals.

Table 3 (41Pb Removal Step) H2SO4 was added to the extract after Fe removal in (3) above to adjust the pH to 2 to 3, and K powder was added and the ion exchange reaction was carried out until the pH was 5. As shown in Table 4. (Fb, Cd is 1
is removed to below my/l.

Table 4 (5) Zinc carbonate manufacturing process 10
2-5% Na2C in ~20% zinc sulfate solution
O3 solution was added to terminate the reaction at pH 6.7 to 7.2, and washing with water → standing → draining was repeated four or more times to remove IJh2E)4, and highly pure basic zinc carbonate was obtained.

The purity and impurities of the obtained basic zinc carbonate are shown in Table 5 in comparison with the conventional method.

(Note) (Il Conventional method...dry method (method of recovering Zn compounds by reducing and volatilizing them) ([I] Purity of basic zinc carbonate is calculated value, Zn and Z
The nO purity is an actual value.

As is clear from Table 5, it can be seen that the method of the present invention is extremely superior in terms of purity and impurities of basic zinc carbonate compared to the conventional method. Incidentally, by implementing this method, 70 tons of basic zinc carbonate are recovered per month.

The dropping rate of H2SO4 in the above experimental example was
1.9 K+ up to PH5! /min, pH
Up to 3.5±0.2, it is set as 0.3 ken and A in, and adjustments are made according to the setting of the payout.

As explained in detail above, according to the method of the present invention, Fe,
Since it also contains Pb1C/, it has a great effect in that highly pure blood can be efficiently recovered from the contained substances.

[Brief explanation of drawings]

The figure is a process diagram showing an example of the method of the present invention.

Claims (2)

[Claims] (1) Sulfuric acid is added to the slurry in which the Zn-containing material, which also contains impurities such as Fe, Pb, and Cl, is removed to remove water-soluble impurities, and then sodium carbonate is added to extract the Zn component.
Add an oxidizing agent to H4~5 after adjustment to convert Fe^2^+ to Fe^
Oxidize to 3^+ to separate and remove Fe and trace amounts of heavy metals as precipitates, add Zn powder and sulfuric acid to the extract after Fe removal to remove Pb, and carbonate the resulting solution. Z characterized in that it is recovered as basic zinc carbonate by
A method for recovering Zn from n-containing materials. (2) Sulfuric acid is added to the slurry in which the Zn-containing material, which also contains impurities such as Fe, Pb, and Cl, is removed to remove water-soluble impurities, and sodium carbonate is added to extract the Zn component.
Add an oxidizing agent to H4~5 after adjustment to convert Fe^2^+ to Fe^
Oxidize to 3^+ to separate and remove Fe and trace amounts of heavy metals as precipitates, add Zn powder and sulfuric acid to the extract after Fe removal, filter and separate, return the filtered cake to the Zn extraction process, and extract Zn is removed from the Zn-containing material by adding sodium carbonate to the prepared zinc sulfate solution, washing with water, recovering basic zinc carbonate, and using the supernatant liquid as washing water for the Zn-containing material. How to collect.