JP2007313505A - Method for treating arsenic containing solution - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for recovering a powder of a compound of iron and arsenic, which has a very low concentration of arsenic eluted from the powder, by treating an arsenic containing solution, e.g., a high purity and high concentration arsenic containing solution obtained by treating an arsenic containing substance which contains various elements other than arsenic, such as an intermediate product in a nonferrous metal smelting or refining process. <P>SOLUTION: Bivalent ferrous ions are added to a pentavalent arsenic containing solution, which contains 10 g/L or more of arsenic, so as to cause the molar ratio (Fe/As) of iron to arsenic in the solution to be not less than 1 (preferably, 1 to 1.5), and an oxidizing agent is added to the solution to allow a reaction at a temperature of not lower than 70°C (preferably, 70 to 95°C) to cause, while stirring the solution. Then, a solid-liquid separation is carried out, and solid part separated by the solid-liquid separation is dried. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for treating an arsenic-containing solution, and in particular, a high-purity and high-concentration arsenic-containing solution obtained by treating an arsenic-containing substance containing various elements other than arsenic, such as a non-ferrous smelting intermediate. The processing method of the arsenic containing solution like this.

  Various smelting intermediates and smelting raw materials produced in non-ferrous smelting contain valuable metals, but also contain undesirable elements such as arsenic.

Conventionally, as a method of leaching arsenic from a smelting intermediate containing arsenic and separating and recovering it, a method of separating arsenic by a wet reaction and recovering an arsenic-containing solution has been proposed (for example, Patent Document 1). reference). Further, a method has been proposed in which arsenic present in an iron arsenate solution is removed and fixed as a stable crystalline and non-eluting iron / arsenic compound with iron (see, for example, Patent Document 2). In addition, at least one of an iron (II) solution and an iron (III) solution is added to the arsenic-containing solution and reacted to form Scorodite (FeAsO ₄ .2H ₂ O), which is separated into solid and liquid and contains copper. Collect scorodite containing non-ferrous metal component, add water to scorodite containing non-ferrous metal component containing copper and repulp, dissolve non-ferrous metal component containing copper contained in scorodite in liquid and from scorodite A separation method has been proposed (see, for example, Patent Document 3). Further, arsenic is leached from the ash containing arsenic with an acid solution, and an acidic aqueous solution containing iron ions is mixed into the leached solution to precipitate amorphous iron arsenate (FeAsO ₄ ), and then the mixture is heated. Then, a method has been proposed in which amorphous iron arsenate is crystallized, and the mixed liquid is filtered to remove the crystallized iron arsenate (see, for example, Patent Document 4). In addition, stability evaluation of iron arsenate as a compound of iron and arsenic has been reported (for example, see Non-Patent Document 1).

Japanese Examined Patent Publication No. 61-24329 (page 1-3) JP 11-277075 A (paragraph number 0013-0014) JP 2000-219920 A (paragraph number 0007) Japanese Patent Laying-Open No. 2005-161123 (paragraph number 0006) Tohoku University Beneficiation and Smelting Research Institute Vocabulary Vol. 34 No. 1 Reprint (June 1978), Report of Beneficiation and Smelting Research Institute No. 764, “Solubility products of iron arsenate, calcium arsenate, and magnesium arsenate (Tadahisa Nishimura, Izawa Tozawa)

  However, Patent Document 1 proposes a method for collecting an arsenic-containing solution, but does not propose a method for fixing the collected arsenic-containing solution to a stable non-eluting substance. Further, it is more stable than conventional iron and arsenic compounds produced by the methods of Patent Documents 2 to 4 and conventional iron and arsenic compounds such as iron arsenate reported in Non-Patent Document 1 and the like. It is desirable to produce leachable iron and arsenic compounds. In particular, the method of Patent Document 4 has a problem that it takes a very long time because amorphous iron arsenate is crystallized after the amorphous iron arsenate is precipitated.

  Therefore, in view of such conventional problems, the present invention provides high-purity and high-concentration arsenic obtained by treating an arsenic-containing material containing various elements other than arsenic, such as non-ferrous smelting intermediates. An object of the present invention is to provide a method of treating an arsenic-containing solution such as a containing solution and recovering it as a compound of iron and arsenic with a very low arsenic elution concentration.

  As a result of diligent research to solve the above problems, the inventors of the present invention added a divalent iron ion to a solution containing pentavalent arsenic of 10 g / L or more, and a molar ratio of iron to arsenic in the solution ( Fe / As) is set to 1 or more, and an oxidant is added and reacted at a temperature of 70 ° C. or higher while stirring, and then solid-liquid separation is performed to recover the solid content. The present inventors have found that it can be recovered as an arsenic compound and have completed the present invention.

  That is, in the method for treating an arsenic-containing solution according to the present invention, a divalent iron ion is added to a solution containing 10 g / L or more of pentavalent arsenic so that the molar ratio of iron to arsenic in the solution is 1 or more. It is characterized in that after adding an agent and reacting at a temperature of 70 ° C. or higher with stirring, the solid content is separated by solid-liquid separation.

  In this method for treating an arsenic-containing solution, the reaction is preferably carried out with stirring at atmospheric pressure, the molar ratio of iron to arsenic is preferably 1 to 1.5, and the reaction temperature is 95 ° C. or lower. Is preferred. The arsenic concentration in the solution is preferably 20 g / L or more. Further, it is preferable to add iron (II) sulfate heptahydrate as a divalent iron ion to the solution. Furthermore, oxygen gas can be used as an oxidizing agent.

  In the method for treating an arsenic-containing solution, the step of obtaining a leachate containing arsenic by solid-liquid separation after the arsenic-containing solution is alkali-leached while oxidizing the arsenic-containing substance to an alkaline solution to a pH of 10 or higher and oxidizing the solution. A step of adding an alkaline earth metal or a salt thereof to the leachate, followed by solid-liquid separation to obtain a residue containing a compound of arsenic and an alkaline earth metal; and washing and adding the residue to the sulfuric acid solution An arsenic-containing solution produced by a method comprising a step of obtaining a arsenic-containing solution by liquid separation is preferable. In this case, when manufacturing the arsenic-containing solution, use an arsenic-containing substance containing sulfur as the arsenic-containing substance, or if the arsenic-containing substance does not contain sulfur, add sulfur to the arsenic-containing substance or the leachate, Furthermore, it is preferable that the amount of the alkaline earth metal or salt thereof added to the leaching solution is greater than or equal to the amount of the alkaline earth metal or salt thereof necessary to produce a compound of arsenic and alkaline earth metal.

  According to the present invention, an arsenic-containing solution such as a high-purity and high-concentration arsenic-containing solution obtained by treating an arsenic-containing substance containing various elements other than arsenic, such as a non-ferrous smelting intermediate, is treated. Thus, it can be recovered as a powder of an iron and arsenic compound with a very low elution concentration of arsenic.

  FIG. 1 is a process diagram schematically showing an embodiment of a method for treating an arsenic-containing solution according to the present invention. As shown in FIG. 1, an embodiment of the method for treating an arsenic-containing solution according to the present invention is as follows. (1) After leaching an alkali while oxidizing it to an pH of 10 or more, preferably 12 or more by adding an arsenic-containing substance to the alkali solution. Alkaline leaching / oxidation step for obtaining a leaching solution containing arsenic by solid-liquid separation, and (2) adding an alkaline earth metal or a salt thereof to the leaching solution, followed by solid-liquid separation and containing a compound of arsenic and alkaline earth metal An alkaline earth metal replacement step for obtaining a residue; (3) a washing step for washing the residue to remove the adhering alkaline solution; and (4) a solid-liquid separation after adding the washed residue to the sulfuric acid solution. An arsenic-containing solution is produced by a method for producing an arsenic-containing solution comprising a sulfuric acid dissolving step for obtaining a high-purity and high-concentration arsenic-containing solution. (5) Fe salt is added to the arsenic-containing solution and reacted. Later solid-liquid separation, washed and subjected to solid-liquid separation and a step of obtaining a compound of iron and arsenic. The compound of iron and arsenic thus obtained has coarse crystal grains and a very low arsenic elution concentration, and can be discarded, deposited or stored. Hereinafter, each of these steps will be described.

As the arsenic-containing substance used as a raw material for the method for producing the arsenic-containing solution, a substance containing sulfur and arsenic such as sulfides such as arsenic sulfide (As ₂ S ₃ ) and FeAsS can be used. Also, such residue composed mainly of the resulting copper arsenide (Cu 3 _As) due zinc smelting process can also be used. The residue mainly composed of copper arsenide contains valuable metals such as indium and gallium in addition to zinc and iron. If the arsenic-containing material to be treated by the method for treating an arsenic-containing material of the embodiment does not contain sulfur, a sulfate such as Na ₂ SO ₄ salt is added before the alkali leaching / oxidation step, or Alternatively, it is necessary to add sulfate or the like to the leaching solution after the alkali leaching / oxidation step so that SO ₄ ions are present in the leaching solution before the alkaline earth metal replacement step. In addition to arsenic (As) and sulfur (S), arsenic-containing substances include copper (Cu), zinc (Zn), iron (Fe), indium (In), gallium (Ga), tin (Sn), It may contain at least one of antimony (Sb), lead (Pb), cadmium (Cd), sodium (Na), potassium (K), magnesium (Mg) and calcium (Ca).

(1) Alkali leaching / oxidation step First, the above-mentioned arsenic-containing substance is added to an alkaline solution together with an oxidizing agent so as to have a pH of 10 or more, preferably 12 or more, and the reaction is carried out while stirring at a liquid temperature of 50 to 100 ° C. Leaching while oxidizing the arsenic-containing material. The reaction in the alkali leaching / oxidation step is a reaction that occurs at a strong alkalinity of pH 10 or more, preferably pH 12 or more, and the reaction rate is very fast.

  By this alkali leaching, Cu and As can be separated by leaching As without leaching Cu. In this alkaline leaching, In, Pb, Cd and Mg are not leached, and Fe, Sn, Sb and Ca are hardly leached. However, since Ga is almost leached, As and Ga are not separated at this stage.

  Zn is leached when the alkali concentration is high, but is not leached when the alkali concentration is low. Therefore, the quality of Zn in the arsenic-containing material, the quality of arsenic, and the leaching behavior of other impurities (especially Sn and Sb) are affected. The alkali concentration may be determined in consideration. That is, if the quality of Sn or Sb is low, it is better to leave Zn in the residue, but if the quality of Sn or Sb is high, it is better to dissolve Zn to some extent.

  A NaOH solution can be used as the alkaline solution, in which case the NaOH concentration is preferably 50 to 300 g / L.

  As an oxidizing agent, hydrogen peroxide, ozone, etc. can be used in addition to a solid oxidizing agent such as potassium permanganate, but air or oxygen with increased concentration may be used. Oxidation reaction proceeds easily by bubbling and stirring the gas.

  Solid-liquid separation is performed after alkali leaching. This solid-liquid separation may be any of general filtration such as a filter press, centrifugal separation, decanter, and belt filter, and its type and conditions are determined in consideration of filterability, dewaterability, washability, and the like.

  On the other hand, since the solid content after the solid-liquid separation is a metallic compound containing valuable Cu or In and a partially oxidized compound, it can be effectively utilized in the smelting process. In copper smelting, an anode can be created by directly charging into a flash smelting furnace or a reflection furnace.

(2) Alkaline earth metal replacement step Next, alkaline earth is added to the leachate (mainly a liquid containing Na and As) after solid-liquid separation. When an alkaline earth such as CaO is added to the leachate after alkaline leaching, the alkaline earth metal reacts with arsenic to produce a compound of alkaline earth metal and arsenic, and an alkaline liquid such as NaOH is regenerated.

By adding an excess of alkaline earth for the above reaction, SO ₄ salts or ions are mixed in the regenerated alkaline liquid to prevent the alkaline earth metal from being mixed into the alkaline liquid. In the case where the regenerated alkaline solution has no SO ₄ salt and is a substantially pure alkaline solution, if the alkaline earth is added excessively, the alkaline earth metal is dissolved in the regenerated alkaline solution.

If alkaline earth metal is present in the regenerated alkaline liquid, when the alkaline liquid is reused for arsenic leaching, arsenic and alkaline earth metal react to produce a precipitate with low solubility. The leaching rate in the leaching process may become extremely poor. On the other hand, if excess alkaline earth metal is not added, arsenic will remain in the alkaline solution without being removed, and the arsenic recovery efficiency will be very poor. In addition, when SO ₄ is mixed in the alkaline solution, when CaO is used as the alkaline earth, CaO or Ca (OH) ₂ remains in the solid content without being dissolved in that state. That is, by increasing the concentration of Na ⁺ and SO ₄ ²⁻ , the solubility of Ca ²⁺ is suppressed to be very low, so that it remains in the solid content as CaO.

The amount of alkaline earth added may be equivalent to produce a compound of arsenic and alkaline earth metal, but is equivalent to produce Ca (OH) ₂ in addition to Ca ₃ (AsO ₄ ) _2. It is preferable to make it slightly richer in alkaline earth.

(3) Washing step Next, the alkaline solution adhering to the arsenic and alkaline earth metal compound obtained as a solid content is washed with water. In this water washing, it is necessary to keep arsenic in the solid content. This is because if arsenic elutes into the washing waste water, a complicated operation for removing the arsenic in the waste water becomes necessary. In order to avoid such an operation, it is necessary to remove the alkaline solution by washing but not to remove arsenic. In order to enable such cleaning, it is preferable that the alkaline earth is made rich by alkaline earth when the alkaline earth is added as described above. Further, when the alkaline earth is rich, not only the alkaline solution is washed away but also the alkaline earth metal is preferentially eluted, and the compound of arsenic and alkaline earth metal is retained as it is. In addition, although the addition amount of alkaline-earth increases with the increase in the quantity of washing water, it is preferable to make it excess 0.5-1.0 mass% rather than the quantity which reacts with As.

(4) Sulfuric acid dissolution step Next, the washed arsenic and alkaline earth metal compound is added to the sulfuric acid solution and reacted with vigorous stirring to re-dissolve arsenic and produce gypsum. This arsenic and alkaline earth metal compound is insoluble on the alkali side, but almost completely dissolves when the pH is 4 or less. Therefore, if the pH is lowered to 4 or less with mineral acid, almost all of the compound can be dissolved. It is. However, in order to separate arsenic and alkaline earth metal, it is preferable to separate into gypsum and an arsenic-containing solution using sulfuric acid. When a compound of arsenic and alkaline earth metal is added to the sulfuric acid solution, precipitation of alkaline earth and sulfate occurs simultaneously with the dissolution of arsenic.

  The concentration of the sulfuric acid solution is preferably 100 to 500 g / L, and more preferably 150 to 300 g / L. To increase the concentration of arsenic in the arsenic-containing solution, it is necessary to increase the concentration of the sulfuric acid solution. However, the concentration of the sulfuric acid solution adhering to the gypsum produced increases, and the viscosity of the solution also increases. Therefore, it is not preferable. However, from the viewpoint of preventing unreacted arsenic, the compound of arsenic and alkaline earth metal is added to concentrated sulfuric acid to dissolve not only arsenic but also gypsum, and then water is added to precipitate gypsum by hydrolysis. May be.

  Stirring is preferably performed strongly. Arsenic dissolution reaction and gypsum precipitation reaction occur at the same time, and it is preferable to put it into the sulfuric acid solution in the form of a wet cake. In addition, it is necessary to vigorously agitate to sufficiently contact arsenic with sulfuric acid to obtain a high-purity and high-concentration arsenic-containing solution.

(5) Step of generating Fe and As compound Next, divalent iron ions are added to the obtained arsenic-containing solution so that the molar ratio of iron to arsenic (Fe / As) in the solution is 1 or more and oxidation is performed. After adding the agent and stirring, the temperature is raised to 70 ° C. or higher to react, and then the solid content obtained by solid-liquid separation is dried.

  The concentration of As in the arsenic-containing solution may not be so high as long as the amount of Na contained as an impurity is 1 g / L or less, but if the concentration of As is low, particles are formed during the growth process from precipitation of a compound of Fe and As. Since there exists a tendency which becomes difficult to coarsen, it is preferable that it is 10 g / L or more, and it is further more preferable that it is 20 g / L or more. Further, the pH of the arsenic-containing solution is preferably 2 or less. If the As concentration in the arsenic-containing solution is high, salts such as Na, Mg, Cu, Zn, and Mn may coexist as impurities in the solution.

As the divalent Fe source, soluble FeSO ₄ · 7H ₂ O is preferably used. The molar ratio of iron to arsenic (Fe / As) in the solution is preferably 1 or more, and more preferably about 1.0 to 1.5.

As the oxidizing agent, any oxidizing agent capable of oxidizing Fe ²⁺ can be used, but an oxidizing agent capable of controlling the oxidation rate is preferable, and oxygen gas, air, or the like is preferably used. Even when KMnO ₄ or the like is used as the oxidizing agent, the oxidation rate can be controlled by controlling the amount added.

  If the reaction temperature is 50 ° C. or higher, the compound of Fe and As can be precipitated. However, in order to reduce the elution concentration of As, it is preferably 70 ° C. or higher, and is about 80 to 95 ° C. Is more preferable. The reaction time may be 1 to 3 hours.

  Examples of the method for treating an arsenic-containing solution according to the present invention will be described in detail below.

[Example 1]
First, an arsenic-containing material having the composition shown in Table 1 was prepared as a starting material. 400 g of this arsenic-containing substance is placed in 4 L of NaOH solution (Na concentration 57.5 g / L) having a NaOH concentration of 100 g / L, heated to a liquid temperature of 90 ° C., and air (gas / liquid ratio = 0.0) at a flow rate of 2 L / min. 5) was blown in and allowed to react for 1 hour with stirring, and alkali leaching was performed while oxidizing the arsenic compound. The pH after the arsenic-containing substance was added to the NaOH solution was about 12.

  Next, after cooling to a liquid temperature of 70 ° C., a membrane filter made of PTFE (polytetrafluoroethylene) having an opening of 3 microns is pressurized to 0.4 MPa by a pressure filter and remains on the filter. The solid residue was separated into a residue (leaching residue) and a filtrate (alkaline leachate) that passed through the filter. The obtained leach residue had a water content of 20% and a mass of 600 g.

Next, 95% pure industrial quicklime (CaO) is added to the alkaline leachate, heated to a liquid temperature of 60 ° C., stirred and reacted for 1 hour to obtain a compound of Ca and As as a solid content, and NaOH. The liquid was regenerated. The liquid temperature rose from 60 ° C. to 80 ° C. by this substitution reaction. The amount of industrial quicklime added was the same as that of CaO sufficient to replace the alkaline leaching solution in relation to the NaOH concentration of the NaOH solution added during the alkaline leaching. Moreover, since water (H ₂ O) is consumed when CaO is added, in order to avoid an increase in concentration, water was replenished and adjusted so that the alkaline leachate was the same amount.

  Next, after cooling to a liquid temperature of 70 ° C., solid-liquid separation was performed with a pressure filter. The resulting residue (solid content of arsenic and alkaline earth metal salt) contained 20% water and was 158 g / L.

  Next, in order to remove the alkali component adhering to the solid content after solid-liquid separation, repulp washing was performed three times with a pulp concentration of 200 g / L. In each repulp washing, the liquid temperature was 60 ° C. and the reaction was performed for 1 hour with stirring. Then, using a membrane filter made of PTFE having a mesh size of 3 microns, the pressure is reduced to 0.4 MPa by a pressure filter, and the residue (solid content including calcium and arsenic after washing) and the filter remaining on the filter are removed. The filtrate that passed through (liquid after washing) was subjected to solid-liquid separation.

  Next, 1912 g of the residue after washing (solid content of calcium and arsenic containing 20% water) was added to 5.59 L of a 200 g / L sulfuric acid solution to adjust to pH 1, and the liquid temperature was 50 ° C. and the mixture was vigorously stirred. For 2 hours to redissolve the residue. The liquid temperature rose from 50 ° C. to 80 ° C. by this substitution reaction.

  After that, using a membrane filter made of PTFE having a mesh size of 3 microns, the pressure (0.4 g) was pressurized by a pressure filter and the residue (gypsum) remaining on the filter and the filtrate that passed through the filter (arsenic-containing solution) Separated into solid and liquid. The composition of the filtrate thus obtained was subjected to composition analysis, and as shown in Table 2, it was a solution containing a high concentration of arsenic such as an alkaline earth metal and had a pH of 1.0.

Next, 486 mL of the obtained arsenic-containing solution and 214 mL of a solution prepared by adding water to the first grade reagent FeSO ₄ .7H ₂ O so that the Fe concentration becomes 183 g / L (the total of this solution and the arsenic-containing solution) Is put in a 1 L titanium sealed container (reaction vessel) (As concentration 50.13 g / L, Fe concentration 56.00 g / L, Fe / As ratio = 1.5), The atmosphere in the container was set to an inert gas atmosphere, and the temperature of the single-stage flat paddle was increased to 500 rpm while stirring. When the temperature in the container reached 100 ° C. or higher, the inert gas was once degassed, and then the temperature was raised to a final set temperature of 175 ° C. At this time, the pressure in the container rose to 0.8 MPa.

  When the final set temperature reached 175 ° C., oxygen gas with a purity of 99% or more was blown into the container, and the temperature and pressure (the partial pressure of oxygen was 0.2 MPa, and the total pressure in the container was 1.0 MPa). ) Was allowed to react for 5 hours. After 5 hours, heating to the container was stopped, and the container was cooled to 100 ° C. or less in about 1 hour, and then the container was opened to the atmosphere, and the solution in the container was taken out. After the temperature of this solution reached 70 ° C., solid-liquid separation was performed by applying pressure to 0.4 MPa with a pressure filter using a membrane filter made of PTFE having an opening of 3 μm. The amount of the obtained filtrate (reaction solution) was 640 mL.

In addition, the filtration rate (per 1 m < ² > filtration area of a pressure filter) was measured by measuring the time from the start of pressure filtration until air blows through. In addition, the pH and redox potential (ORP) of the post-reaction solution separated into solid and liquid were measured, and the sulfuric acid concentration (free acid (FA) concentration) in the post-reaction solution and the compositional analysis of each element were performed by ICP. It was. These conditions and results are shown in Tables 3 to 5.

  In addition, when the valence analysis of As was analyzed by the thionalide method, 99% was pentavalent As, and when the valence analysis of Fe was analyzed by the absorptiometry, all were trivalent.

  On the other hand, the wet weight of the solid content obtained by solid-liquid separation was measured, and water was added to 1 L of water with respect to 100 g of the solid content on a wet base to perform repulp washing. In this repulp washing, the liquid temperature was set to 30 ° C. and stirred at 400 rpm for 1 hour. After this washing, solid-liquid separation was performed again using a pressure filter.

The weight of the cake obtained as a solid content by this solid-liquid separation was measured, dried at 60 ° C. for 18 hours, and then lightly crushed in an agate mortar, composition analysis, dissolution test, wet particle size Distribution measurement, specific surface area measurement by N ₂ gas adsorption method (BET 1-point method), Beckman type specific gravity measurement, compression density by 1 ton pressurization were measured. The composition analysis was performed by ICP after once dissolving in water. The wet particle size distribution was measured using a wet particle size distribution measuring device (LA500 manufactured by Horiba, Ltd.). Specific surface area measurement by N ₂ gas adsorption was performed by a BET one-point method using a specific surface area measuring device (Monosorb manufactured by Yuasa Ionics). In addition, the dissolution test is based on the Environmental Agency Notification No.13. After mixing 1 L of water with a pH of 5 with 100 g of solid content and stirring for 6 hours with a dedicated machine for dissolution test, a 0.45 micron membrane filter is used. The arsenic concentration in the filtrate (eluate) obtained by solid-liquid separation using was analyzed.

  From the analysis results, the Fe / As ratio, the amount of generated residue (the amount per 1 ton of As determined from the arsenic quality and moisture value), and the amount of liquid to be processed (As 1 ton determined from the As concentration before and after the treatment solution) are removed. The amount of liquid required for the calculation was calculated.

  Further, the obtained powder was subjected to powder X-ray diffraction using an X-ray diffractometer. In this powder X-ray diffraction, the counter cathode is Kα of Cu, wavelength λ = 1.5418 angstrom, tube voltage = 50 kV (partial 40 kV), tube current = 300 mA, scanning speed 0.01 ° / sec, scanning angle 2θ = A scintillation counter was used at 5 ° to 85 °. Whether the obtained diffraction image is crystalline or not and whether a halo pattern is observed around the low-angle side was determined to be amorphous or crystalline. The particles were observed with a scanning electron microscope (SEM).

  These results are shown in Tables 6-8.

  As shown in Table 8, Fe / As (molar ratio) of the obtained powder was 1.01, and from the result of X-ray diffraction, it was found that a powder of crystalline iron and arsenic compound was obtained. It was. Further, the elution concentration of arsenic from the obtained powder of iron and arsenic compound was 0.03 mg / L, which was much lower than the reference value (0.3 mg / L).

[Example 2]
The same arsenic-containing solution (solution having the composition shown in Table 2) as in Example 1 was used, except that the stirring speed was 1000 rpm and the reaction temperature (final set temperature) was 95 ° C. Reacted by the method.

In addition, the filtration rate (per 1 m < ² > filtration area of a pressure filter) was measured by measuring the time from the start of the pressure filtration at the time of the solid-liquid separation of the reaction product until air blows through. In addition, the pH and redox potential (ORP) of the post-reaction solution separated into solid and liquid were measured, and the sulfuric acid concentration (free acid (FA) concentration) in the post-reaction solution and the compositional analysis of each element were performed by ICP. It was. These conditions and results are shown in Tables 3 to 5.

  Moreover, the measurement and calculation similar to Example 1 were performed about the powder obtained by processing the solid content obtained by solid-liquid separation of a reaction product like Example 1. FIG. The results are shown in Tables 6-8. Moreover, the scanning electron microscope (SEM) photograph and X-ray diffraction (XRD) data of 5000 times the powder obtained in this example are shown in FIGS. 2 and 3, respectively.

  From the results of Example 1 and Example 2, when an arsenic-containing solution having a high purity and a high arsenic concentration was reacted with Fe, a precipitate was obtained regardless of the reaction temperature, and the As removal rate was good at 97%. Because the moisture content is low, the volume of solids is small, the arsenic content is high, the filterability is good, crystalline precipitates can be obtained, and the attached salt can be removed by simple washing It can be seen that the elution concentration of arsenic is much lower than the reference value (0.3 mg / L).

[Example 3]
Except for using 40 g / L of Zn in the same arsenic-containing solution as in Example 1 (solution having the composition shown in Table 2), after reacting in the same manner as in Example 1, the reaction product The solid content obtained by solid-liquid separation was treated in the same manner as in Example 1, and the same measurement and calculation as in Example 1 were performed on the obtained powder. The conditions and results are shown in Tables 3 to 8.

  As shown in Table 8, the Fe / As (molar ratio) of the obtained powder was 0.98, and from the results of X-ray diffraction, it was found that a powder of crystalline iron and arsenic compound was obtained. It was. The elution concentration of arsenic from the obtained powder of iron and arsenic compound was 0.05 mg / L, which was much lower than the reference value (0.3 mg / L).

[Example 4]
Except for using 40 g / L of Zn in the same arsenic-containing solution (solution having the composition shown in Table 2) as in Example 1, the reaction product was reacted in the same manner as in Example 2 The solid content obtained by solid-liquid separation was treated in the same manner as in Example 2, and the same measurement and calculation as in Example 1 were performed on the obtained powder. The conditions and results are shown in Tables 3 to 8.

  As shown in Table 8, Fe / As (molar ratio) of the obtained powder was 1.05. From the result of X-ray diffraction, it was found that a powder of crystalline iron and arsenic compound was obtained. It was. The elution concentration of arsenic from the obtained powder of iron and arsenic compound was 0.06 mg / L, which was much lower than the reference value (0.3 mg / L). From this result, even if zinc coexists in the arsenic-containing solution, the arsenic elution concentration is very low, and the processing method of the arsenic-containing solution according to the present invention can be applied to the treatment of the zinc smelting process liquid. I understand.

[Example 5]
An arsenic-containing solution (solution having the composition shown in Table 2) similar to that in Example 1 was placed in a 2 L glass open container (reaction vessel), the stirring speed was 1000 rpm, and the reaction temperature (final set temperature) was After reacting by the same method as in Example 1 except that the reaction time was 95 ° C. and 7 hours, the solid content obtained by solid-liquid separation of the reaction product was treated in the same manner as in Example 1 to obtain The obtained powder was subjected to the same measurements and calculations as in Example 1. The conditions and results are shown in Tables 3 to 8.

  As shown in Table 8, Fe / As (molar ratio) of the obtained powder was 1.07. From the result of X-ray diffraction, it was found that a powder of crystalline iron and arsenic compound was obtained. It was. Further, the elution concentration of arsenic from the obtained powder of iron and arsenic compound was 0.02 mg / L, which was much lower than the reference value (0.3 mg / L).

[Example 6]
An arsenic-containing solution similar to that in Example 1 (solution having the composition shown in Table 2) was diluted with water, the As concentration in the solution was 30.02 g / L, and the Fe concentration was 33.63 g / L (Fe / As ratio = Except for 1.5), after reacting in the same manner as in Example 5, the solid content obtained by solid-liquid separation of the reaction product was treated in the same manner as in Example 1, and the resulting powder was obtained. The same measurements and calculations as in Example 1 were performed. The conditions and results are shown in Tables 3 to 8.

  As shown in Table 8, Fe / As (molar ratio) of the obtained powder was 1.02, and from the result of X-ray diffraction, it was found that a powder of crystalline iron and arsenic compound was obtained. It was. Further, the elution concentration of arsenic from the obtained powder of iron and arsenic compound was 0.02 mg / L, which was much lower than the reference value (0.3 mg / L).

[Example 7]
The same arsenic-containing solution (solution having the composition shown in Table 2) as in Example 1 was diluted with water, the As concentration in the solution was 20.07 g / L, and the Fe concentration was 22.41 g / L (Fe / As ratio = Except for 1.5), after reacting in the same manner as in Example 5, the solid content obtained by solid-liquid separation of the reaction product was treated in the same manner as in Example 1, and the resulting powder was obtained. The same measurements and calculations as in Example 1 were performed. The conditions and results are shown in Tables 3 to 8.

  As shown in Table 8, Fe / As (molar ratio) of the obtained powder was 1.03. From the result of X-ray diffraction, it was found that a powder of crystalline iron and arsenic compound was obtained. It was. Further, the elution concentration of arsenic from the obtained powder of iron and arsenic compound was 0.02 mg / L, which was much lower than the reference value (0.3 mg / L).

[Example 8]
Instead of the same arsenic-containing solution as in Example 1 (solution having the composition shown in Table 2), the first grade arsenic liquid (pentavalent arsenic liquid) (containing 500 g / L arsenic) was diluted to a capacity of 5 L Put in an airtight container (reaction tank), set As concentration in the solution to 10.00 g / L, Fe concentration to 11.18 g / L (Fe / As ratio = 1.5), stirring speed to 360 rpm, oxygen content The reaction was carried out in the same manner as in Example 1 except that the pressure was 0.3 MPa and the repulp washing after the solid-liquid separation was performed twice, and then the solid content obtained by solid-liquid separation of the reaction product was carried out. The same processing as in Example 1 was carried out, and the same measurement and calculation as in Example 1 were performed on the obtained powder. The conditions and results are shown in Tables 3 to 8.

  As shown in Table 8, Fe / As (molar ratio) of the obtained powder was 1.20, and it was found from the result of X-ray diffraction that a powder of crystalline iron and arsenic compound was obtained. It was. Further, the elution concentration of arsenic from the obtained powder of iron and arsenic compound was 0.02 mg / L, which was much lower than the reference value (0.3 mg / L).

[Example 9]
Except that the concentration of As in the solution placed in a glass open container (reaction vessel) with a capacity of 2 L was 10.1 g / L and the Fe concentration was 11.21 g / L (Fe / As ratio = 1.5), After reacting by the same method as in Example 5, the solid content obtained by solid-liquid separation of the reaction product was treated in the same manner as in Example 1. The obtained powder was measured in the same manner as in Example 1. Calculated. The conditions and results are shown in Tables 3 to 8.

  As shown in Table 8, the Fe / As (molar ratio) of the obtained powder was 1.03. From the result of X-ray diffraction, it was found that an amorphous iron-arsenic compound powder was obtained. . The elution concentration of arsenic from the obtained powder of iron and arsenic compound was 0.01 mg / L, which was much lower than the reference value (0.3 mg / L).

[Comparative Example 1]
Using polyiron (Fe ³⁺ ) instead of the primary reagent FeSO ₄ · 7H ₂ O, As concentration 47.97 g / L, Fe concentration 53.77 g / L, Fe / As ratio = 1.5) Except for the above, after reacting by the same method as in Example 1, the solid content obtained by solid-liquid separation of the reaction product was treated in the same manner as in Example 1. Similar measurements and calculations were performed. The conditions and results are shown in Tables 3 to 8.

  As shown in Table 8, Fe / As (molar ratio) of the obtained powder was 1.04. From the result of X-ray diffraction, it was found that a powder of crystalline iron and arsenic compound was obtained. It was. The elution concentration of arsenic from the obtained powder of iron and arsenic compound was 0.48 mg / L, which was higher than the reference value (0.3 mg / L). In this comparative example, the average particle size is large, the proportion of particles of 5 μm or less is 0%, and the BET specific surface area is small. However, from the result of the SEM image, it is not a dense crystal form but agglomerated. Therefore, it was found that the average particle diameter, the ratio of particles of 5 μm or less, and the BET specific surface area were apparent values.

[Comparative Example 2]
A method similar to Comparative Example 2 except that a solution having an As concentration of 47.97 g / L dissolved in arsenous acid was used instead of the arsenic-containing solution similar to Example 1 (solution having the composition shown in Table 2). After the reaction, the solid content obtained by solid-liquid separation of the reaction product was treated in the same manner as in Example 1. The obtained powder was subjected to the same measurements and calculations as in Example 1. The conditions and results are shown in Tables 3 to 8.

  As shown in Table 8, Fe / As (molar ratio) of the obtained powder was 1.21, and from the results of X-ray diffraction, it was found that a powder of crystalline iron and arsenic compound was obtained. It was. The elution concentration of arsenic from the obtained powder of iron and arsenic compound was 4.45 mg / L, which was much higher than the standard value (0.3 mg / L).

[Comparative Example 3]
Except for setting the final set temperature (reaction temperature) to 70 ° C., the reaction was carried out in the same manner as in Example 5, and then the solid content obtained by solid-liquid separation of the reaction product was obtained in the same manner as in Example 1. The same measurement and calculation as in Example 1 were performed on the processed powder. The conditions and results are shown in Tables 3 to 8.

  As shown in Table 8, Fe / As (molar ratio) of the obtained powder was 1.06. From the result of X-ray diffraction, it was found that a powder of crystalline iron and arsenic compound was obtained. It was. The elution concentration of arsenic from the obtained powder of iron and arsenic compound was 0.32 mg / L, which was higher than the reference value (0.3 mg / L).

[Comparative Example 4]
It was obtained by solid-liquid separation of the reaction product after reacting by the same method as in Example 5 except that the final set temperature (reaction temperature) was 50 ° C. and air was blown in place of oxygen gas. The solid content was treated in the same manner as in Example 1, and the same measurement and calculation as in Example 1 were performed on the obtained powder. The conditions and results are shown in Tables 3 to 8.

  As shown in Table 8, Fe / As (molar ratio) of the obtained powder was 1.01, and from the result of X-ray diffraction, it was found that a powder of crystalline iron and arsenic compound was obtained. It was. The elution concentration of arsenic from the obtained powder of iron and arsenic compound was 22.84 mg / L, which was much higher than the standard value (0.3 mg / L).

[Example 10]
Except for using 80 g / L of Zn in the same arsenic-containing solution (solution having the composition shown in Table 2) as in Example 1, the reaction product was reacted in the same manner as in Example 1 The solid content obtained by solid-liquid separation was treated in the same manner as in Example 1, and the same measurement and calculation as in Example 1 were performed on the obtained powder. The conditions and results are shown in Tables 3 to 8.

  As shown in Table 8, the Fe / As (molar ratio) of the obtained powder was 0.98, and from the results of X-ray diffraction, it was found that a powder of crystalline iron and arsenic compound was obtained. It was. The elution concentration of arsenic from the obtained powder of iron and arsenic compound was 0.21 mg / L, which was lower than the reference value (0.3 mg / L). As can be seen from this result, even when the zinc concentration in the arsenic-containing solution is as high as 80 g / L, the arsenic elution concentration is low, so the arsenic-containing solution processing method according to the present invention is applied to the zinc smelting process liquid. In this case, it can be applied even if the zinc concentration in the zinc refining process liquid is high, and it can cope with variations in the process.

[Example 11]
The reaction product was reacted in the same manner as in Example 5 except that 40 g / L of Zn was used in the same arsenic-containing solution (solution having the composition shown in Table 2) as in Example 1 and then used. The solid content obtained by solid-liquid separation was treated in the same manner as in Example 5, and the same measurement and calculation as in Example 1 were performed on the obtained powder. The conditions and results are shown in Tables 3 to 8.

  As shown in Table 8, Fe / As (molar ratio) of the obtained powder was 1.04. From the result of X-ray diffraction, it was found that a powder of crystalline iron and arsenic compound was obtained. It was. Further, the elution concentration of arsenic from the obtained powder of iron and arsenic compound was 0.02 mg / L, which was much lower than the reference value (0.3 mg / L). From this result, even if zinc coexists in the arsenic-containing solution, the arsenic elution concentration is very low, and if the arsenic concentration in the arsenic-containing solution is high, even if the pressure of the injected oxygen is atmospheric pressure, it is not affected. Therefore, it can be seen that the method for treating an arsenic-containing solution according to the present invention can be applied to the treatment of a normal zinc smelting process liquid.

[Example 12]
The reaction product was reacted in the same manner as in Example 5 except that 40 g / L of Cu was used in the same arsenic-containing solution as in Example 1 (solution having the composition shown in Table 2). The solid content obtained by solid-liquid separation was treated in the same manner as in Example 5, and the same measurement and calculation as in Example 1 were performed on the obtained powder. The conditions and results are shown in Tables 3 to 8.

  As shown in Table 8, Fe / As (molar ratio) of the obtained powder was 1.00, and it was found from the results of X-ray diffraction that a powder of crystalline iron and arsenic compound was obtained. It was. The elution concentration of arsenic from the obtained powder of iron and arsenic compound was 0.08 mg / L, which was much lower than the reference value (0.3 mg / L). From this result, it can be seen that even when copper coexists in the arsenic-containing solution, the arsenic elution concentration is very low, and the processing method of the arsenic-containing solution according to the present invention can be applied to the processing of the copper smelting process liquid. . In addition, if the arsenic concentration in the arsenic-containing solution is high, there is no effect even if the pressure of the blown oxygen is atmospheric pressure. Therefore, the arsenic-containing solution processing method according to the present invention is used for processing a normal copper smelting process liquid. You can see that it can be applied.

[Example 13]
The reaction product was reacted in the same manner as in Example 5 except that 40 g / L of Na was used in the same arsenic-containing solution as in Example 1 (solution having the composition shown in Table 2). The solid content obtained by solid-liquid separation was treated in the same manner as in Example 5, and the same measurement and calculation as in Example 1 were performed on the obtained powder. The conditions and results are shown in Tables 3 to 8.

  As shown in Table 8, Fe / As (molar ratio) of the obtained powder was 1.05. From the result of X-ray diffraction, it was found that a powder of crystalline iron and arsenic compound was obtained. It was. Further, the elution concentration of arsenic from the obtained powder of iron and arsenic compound was 0.07 mg / L, which was much lower than the standard value (0.3 mg / L). From this result, even if sodium coexists in the arsenic-containing solution, the elution concentration of arsenic is very low. It can be seen that it can be applied to processing. It can also be seen that if the arsenic concentration in the arsenic-containing solution is high, there is no effect even if the pressure of the oxygen blown is atmospheric pressure.

[Example 14]
The reaction product was reacted in the same manner as in Example 6 except that 40 g / L of Cu was used in the same arsenic-containing solution as in Example 1 (solution having the composition shown in Table 2). The solid content obtained by solid-liquid separation was treated in the same manner as in Example 6, and the same measurement and calculation as in Example 1 were performed on the obtained powder. The conditions and results are shown in Tables 3 to 8.

  As shown in Table 8, Fe / As (molar ratio) of the obtained powder was 1.02, and from the result of X-ray diffraction, it was found that a powder of crystalline iron and arsenic compound was obtained. It was. Further, the elution concentration of arsenic from the obtained powder of iron and arsenic compound was 0.04 mg / L, which was much lower than the reference value (0.3 mg / L). From this result, even when the arsenic concentration in the arsenic-containing solution is lowered to about 30 g / L, there is no influence even if the pressure of the blown oxygen is atmospheric pressure. It can be seen that even if the concentration is low to some extent, the method for treating an arsenic-containing solution according to the present invention can be applied to the treatment of an ordinary zinc smelting process liquid.

[Example 15]
After reacting by the same method as in Example 12 except that air was blown in place of oxygen gas, the solid content obtained by solid-liquid separation of the reaction product was treated in the same manner as in Example 12 and obtained. The same measurement and calculation as in Example 1 were performed on the obtained powder. The conditions and results are shown in Tables 3 to 8.

  As shown in Table 8, Fe / As (molar ratio) of the obtained powder was 1.01, and from the result of X-ray diffraction, it was found that a powder of crystalline iron and arsenic compound was obtained. It was. Further, the elution concentration of arsenic from the obtained powder of iron and arsenic compound was 0.01 mg / L or less, which was much lower than the reference value (0.3 mg / L). As can be seen from this result, if the arsenic concentration in the arsenic-containing solution is high, there is no influence even if a gas having a low oxygen concentration such as air is blown at atmospheric pressure. The present invention can be applied to the treatment of copper smelting process liquid, and the cost can be reduced.

It is process drawing which shows schematically embodiment of the processing method of the arsenic containing solution by this invention. 3 is a scanning electron microscope (SEM) photograph of the powder obtained in Example 2. FIG. 4 is a graph showing X-ray diffraction (XRD) data of the powder obtained in Example 2. FIG.

Claims (9)

Add divalent iron ions to a solution containing 10 g / L or more of pentavalent arsenic to bring the molar ratio of iron to arsenic in the solution to 1 or more, and react at a temperature of 70 ° C. or higher while adding an oxidizing agent and stirring. And treating the arsenic-containing solution by solid-liquid separation and collecting the solid content. The method for treating an arsenic-containing solution according to claim 1, wherein the reaction is performed with stirring at atmospheric pressure. The method for treating an arsenic-containing solution according to claim 1, wherein the molar ratio of iron to arsenic is 1 to 1.5. The method for treating an arsenic-containing solution according to any one of claims 1 to 3, wherein the temperature is 95 ° C or lower. The method for treating an arsenic-containing solution according to any one of claims 1 to 4, wherein the concentration of arsenic in the solution is 20 g / L or more. 6. The method for treating an arsenic-containing solution according to claim 1, wherein iron (II) sulfate heptahydrate is added to the solution as the divalent iron ion. The method for treating an arsenic-containing solution according to claim 1, wherein the oxidizing agent is oxygen gas. The arsenic-containing solution is obtained by adding an arsenic-containing substance to an alkaline solution and leaching the alkali while oxidizing to obtain a leaching solution containing arsenic by solid-liquid separation and oxidizing the alkaline-earth metal or its A step of solid-liquid separation after adding a salt to obtain a residue containing an arsenic and alkaline earth metal compound, a step of washing the residue and adding it to a sulfuric acid solution, and then solid-liquid separation to obtain an arsenic-containing solution; The method for treating an arsenic-containing solution according to any one of claims 1 to 7, wherein the arsenic-containing solution is produced by a method comprising: In manufacturing the arsenic-containing solution, an arsenic-containing material containing sulfur is used as the arsenic-containing material, or when the arsenic-containing material does not contain sulfur, sulfur is added to the arsenic-containing material or the leachate In addition, the amount of the alkaline earth metal or salt thereof added to the leachate should be more than the amount of the alkaline earth metal or salt required to produce the arsenic and alkaline earth metal compound. The processing method of the arsenic containing solution of Claim 8 characterized by these.

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