AU2007216890A1

AU2007216890A1 - Process for treating electrolytically precipitated copper

Info

Publication number: AU2007216890A1
Application number: AU2007216890A
Authority: AU
Inventors: Shigeo Katsura; Yukio Kimura
Original assignee: Nippon Mining and Metals Co Ltd; Nippon Mining Co Ltd
Current assignee: JX Nippon Mining and Metals Corp
Priority date: 2006-09-27
Filing date: 2007-09-20
Publication date: 2008-04-10
Anticipated expiration: 2027-09-20
Also published as: JP2008081784A; CL2007002747A1; KR100866824B1; JP4216307B2; KR20080028745A; AU2007216890B2

Description

S&FRef: 825850

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Nippon Mining Metals Co., Ltd., of 10-1, Toranomon 2-chome, Minato-ku, Tokyo, 105-0001, Japan Yukio Kimura Shigeo Katsura Spruson Ferguson St Martins Tower Level 31 Market Street Sydney NSW 2000 (CCN 3710000177) Process for treating electrolytically precipitated copper The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5845c(956214_1)

SDESCRIPTION

PROCESS FOR TREA TING ELECTROL YTICALL Y c 1 PRECIPITA TED COPPER Technical Field 00 5 [0001] This invention relates to a process for treating electrolytically

INO

precipitated copper produced during a step for smelting copper, and more particularly a process for individually separating and recovering copper, arsenic, bismuth, and antimony, etc. from electrolytically precipitated copper.

Background Art [0002] Copper ore contains various impurities, including arsenic (As), bismuth and antimony Most of these impurities are volatilized and separated by heat during a dry step of smelting copper, and some of them are entrained into the crude copper, and then are brought to the subsequent electrolytic refinery step.

Part of As, Sb, and Bi contained in the crude copper as a copper anode is eluted into an electrolyte, and the non-eluted portion is precipitated as anode slime to the bottom of an electrolysis tank. Since the amount of copper eluted from the anode is generally higher than that of copper deposited on the cathode, the copper level will gradually increase in the electrolyte. Therefore, part of the electrolyte is extracted into another electrolysis tank to control the quality of the remaining electrolyte. The extracted electrolyte is subjected to decoppering electrolysis to separate and recover Cu and the impurities by depositing them on the cathode or precipitate them to the bottom of the electrolysis tank. In the art, such substances precipitated to the bottom of the electrolysis tank together with those deposited on the cathode are called electrolytically precipitated copper.

[0003] Typically, electrolytically precipitated copper is repeatedly fed back to the smelting step. For this purpose, the impurities are preferably separated from the electrolytically precipitated copper. In addition, As, Sb, and Bi, etc.

may be used as valuables. Thus, there is a need for a technique for individually separating and recovering Cu, As, Sb, and Bi from electrolytically precipitated copper.

950823 I.DOC -2- [0004] For example, Japanese Unexamined Patent Application Publication No. 2002-249827 describes a wet process for separating bismuth and antimony from electrolytically precipitated copper. Particularly, electrolytically precipitated copper containing copper oxide, bismuth and antimony, which has been subject to alkaline treatment is leached with 50 to 200 g/L of sulfuric acid at a solution temperature of 40 to 90 0 C for two to five hours, thereby eluting copper, arsenic, and nickel, etc. and leaving bismuth and antimony as residues. This 00 separates bismuth and antimony from copper and the like. According to the description, the recovery of the copper, arsenic, and nickel leached with sulfuric acid can be achieved by neutralization followed by feeding back to the dry smelting step.

[0005] Japanese Patent No. 3212875 describes a process for recovering arsenic from intermediates in the smelting, and more particularly a process for recovering arsenic comprising adding copper and/or copper oxide to an aqueous solution containing arsenic, and producing arsenic acid by oxidation. The arsenic acid is recovered as calcium arsenate by precipitation with slaked lime.

Disclosure of Invention Problems to be solved by the Invention [0006] However, various problems remain unsolved. For example, if large amounts of impurities are present in electrolytically precipitated copper to be fed back to the smelting step, they inevitably increase the load on the dry step and electrolytic smelting. In addition, it is more preferred, if possible, to recover arsenic in a chemical form more suitable for long-term storage compared to calcium arsenate. In other words, from the viewpoint of separation procedure, stabilities of recovered substances, and recycle properties, conventional treatment systems for electrolytically precipitated copper cannot be best, and should be further improved.

[0007] Thus, one object of the present invention is to provide a more convenient process for individually separating and recovering copper, arsenic, bismuth, and antimony from electrolytically precipitated copper.

Means for solving the Problem [0008] As a result of extensive studies on treatment systems for electrolytically precipitated copper to solve such problems, the inventor has discovered that the following treatment system combining a sequence of 950823 _.DOC -3- 0 operations is unexpectedly effective for treating electrolytically precipitated copper.

SAccordingly, a first aspect of the present invention is a process for treating electrolytically precipitated copper comprising: a first step of, after optionally washing electrolytically Sprecipitated copper with water, leaching with sulfuric acid comprising feeding an Soxygen-containing gas into an electrolytically precipitated copper in a sulfuric N) acid solution, stirring the solution at a temperature for a time sufficient to oxidize wt.% or more of As component contained in the electrolytically precipitated 0o copper to pentavalent As, and then solid-liquid-separating the solution into a

C

post-leaching residue containing Sb component and Bi component, and a sulfuric acid-leached solution containing the pentavalent As component, a second step of adding trivalent iron to the sulfuric acid-leached solution to produce crystalline scorodite (FeAsO 4 O 2H 2 thereby solid-liquid-separating the solution into a residue containing crystalline scorodite and a post-dearsenic solution, an optional third step of, where the post-dearsenic solution contains unreacted Fe, or unreacted Fe and As, adding alkaline to the post-dearsenic solution to produce Fe salts with which As component, if any, is co-precipitated, and then solid-liquid-separating the solution into precipitates containing Fe salts and As component, if any, and a post-deironing solution, and an optional forth step of adding alkaline to the post-deironing solution to precipitate Cu salts, and then solid-liquid-separating the solution into precipitates containing the Cu salts and a post-decoppering solution.

[0009] In one embodiment of the present invention, the leaching with sulfuric acid in the first step includes stirring at 70 to 95 0 C for 4.5 to 11 hours.

[0010] In one embodiment of the present invention, the leaching with sulfuric acid in the first step is conducted without external heating.

[0011] In one embodiment of the present invention, the oxygen-containing gas in the first step is air.

[0012] In one embodiment of the present invention, the feeding and/or stirring of the oxygen-containing gas in the first step is performed through jetting.

[0013] In one embodiment of the present invention, the sulfuric acid-leached solution in the first step has a pH of 0.3 to 2.2.

950823 I1DOC -4- [0014] In one embodiment of the present invention, the leaching with sulfuric acid in the first step oxidizes 95 wt.% or more of the As component to pentavalent SAs.

[0015] In one embodiment of the present invention, the crystalline scorodite in the second step is produced by heating to 60 to 95 0

C.

[0016] In one embodiment of the present invention, the trivalent iron in the second step is provided as ferric sulfate.

00 [0017] In one embodiment of the present invention, the crystalline scorodite N in the second step is produced at a pH of 0.4 to 1.2.

[0018] In one embodiment of the present invention, the alkaline in the third c, step is added until the pH of the post-dearsenic solution reaches the range of 2.2 to [0019] In one embodiment of the present invention, the alkaline in the forth step is added until the pH of the post-deironing solution reaches the range of Is to [0020] In one embodiment of the present invention, the alkaline in the third step and/or the forth step is provided as calcium carbonate.

Advantages [0021] According to the present invention, Cu, As, Bi, and Sb each can be individually separated and recovered from electrolytically precipitated copper.

During the process, As is fixed as stable scorodite, which has lower water solubility than calcium arsenate, and is stable and suitable for long-term storage.

Cu can be fed back to the step of smelting copper, with impurities reduced, resulting in the significant increase of the amount that can be fed back which depends on the purifying ability of the dry step and electrolytic smelting.

Consequently, the present invention can reduce the residence time of copper component in the smelting step, which is contained in electrolytically precipitated copper as an intermediate.

Best Mode for Carrying Out the Invention [0022] Electrolvtically Precipitated Copper Materials intended for the treatment process according to the present invention is mainly electrolytically precipitated copper produced in the smelting process, as described above. However, the treatment process according to the present invention is applicable to any substance having substantially the same 950823_1 .DOC composition as the electrolytically precipitated copper. Accordingly, "electrolytically precipitated copper" as used herein also includes any chemical Ssubstance having substantially the same composition as the electrolytically precipitated copper, regardless of its origin. For example, electrolytically s precipitated copper typically contains Cu: 30 to 70 As: 20 to 50 Bi: 0.1 to 6 Sb: 0.5 to 8 Pb: 0.1 to 10 etc. Any substance having Ssuch a composition can be treated as electrolytically precipitated copper 00 according to the present invention.

[0023] Washing Treatment with Water Prior to the first step, electrolytically precipitated copper may optionally be subject to washing treatment with water. The washing with water can be carried out as follows: an electrolytically precipitated copper is repulped with water, and stirred for 0.5 to 6 hours to elute electrolyte (containing copper sulfate, Ni, Fe) adhered during production of the electrolytically precipitated copper, and trace amounts of Ni and Fe, etc. contained in the electrolytically precipitated copper, followed by filtering the slurry for solid-liquid separation. This step can separate most of the Fe and Ni from the electrolytically precipitated copper.

However, this operation is primarily intended to calculate the amount of zero-valent copper, which is water-insoluble and excludes copper sulfate, from the total copper component in the electrolytically precipitated copper, and to determine more exactly the amount of sulfuric acid required for leaching the electrolytically precipitated copper in the subsequent step. This step is not needed when trace elements such as Ni and Fe are of no great significance, when the copper sulfate content is known, or when only a small amount of electrolyte is incorporated into the electrolytically precipitated copper.

[0024] First Step The first step includes leaching with sulfuric acid comprising feeding an oxygen-containing gas into an electrolytically precipitated copper in a sulfuric acid solution and stirring the solution at a temperature for a time sufficient to oxidize 90 wt.% or more of As component contained in the electrolytically precipitated copper to pentavalent As, and then solid-liquid-separating the solution into a post-leaching residue containing Sb component and Bi component, and a sulfuric acid-leached solution containing the pentavalent As component.

[0025] The leaching reaction generally proceeds according to the following scheme in which Cu is oxidized to Cu 2 and As is oxidized to As S 950823_I.DOC -6- Cu H 2 S0 4 1/202 CuSO 4 H20 I-0 0 (1) 2As 5/20 2 3H 2 0 2H 3 AsO 4 0000 (2) SPreferably, the amount of sulfuric acid used is 1.0 to 1.2 equivalents based on the amount of Cu. Below 1.0 equivalent, the leached solution becomes s weakly acidic. This leads to precipitates such as Cu 3 AsO 4 to form and the leaching rates of Cu and As to decrease. Above 1.2 equivalents, the leaching rates of Cu and As are not affected, but the amount of sulfuric acid used increases.

00 Cu and As may be present at any concentrations in the sulfuric acid solution, and preferably each concentration of Cu 2 a n d As 5 is equal to or less than each i solubilityof Cu 2 and As 5 O t h erwi se the leaching rates of Cu and As may decrease.

When the sulfuric acid-leached solution has a pH of 0.3 or less, solubility of crystalline scorodite subsequently produced in the second step will rapidly increase so that production of the crystalline scorodite may be inhibited. When a pH being 2.2 or more, the iron added is precipitated as iron hydroxide so that iron cannot be effectively used for production of scorodite. For these reasons, the pH is preferably in a range of 0.3 to 2.2, and more preferably in a range of 0.4 to 1.2.

[0026] In leaching with sulfuric acid, stirring, for example, at 70 to 95 0 C for 4.5 to 11 hours, and preferably at 80 to 95°C for 7 to 11 hours ensures the oxidation of As. This can oxidize 90 wt.% or more, preferably 95 wt.% or more, and more preferably 98 wt.% or more of As component to pentavalent As. The leaching with sulfuric acid, which is an exothermic reaction, can be conducted without external heating. Stirring may be performed for a longer period, and the period should be suitably determined in view of a balance between economy and efficiency.

To enhance the oxidation efficiency of As, an oxygen-containing gas should be provided in a fine bubble form, and in a sufficient amount (for example, equivalents of oxygen to copper/7 hours). Thus, vigorous stirring is preferred.

For example, feeding of the oxygen-containing gas and/or stirring are conveniently performed through jetting. The example value is in case ofjetting (trade name: JET AJITER). With a stirrer equipped with conventional turbine blades, reaction efficiency will decrease. For example, even when the amount of the oxygen-containing gas fed is 3.5 times or more the above value, this reaction will take twice or more the above reaction time. Valency control of As at this 950823 I.DOC -7- 2+ stage facilitates production of scorodite in the second step. Cu is also effective for promoting oxidation of As.

[0027] Any oxygen-containing gas that does not significantly have adverse effects on the reaction can be used. For example, pure oxygen, and mixtures of oxygen and inert gases can be used. From the viewpoint of handling and cost, air is preferred.

[0028] To efficiently separate Sb and Bi from the electrolytically precipitated 00 ID copper, preferred are to increase pulp density of the electrolytically Sprecipitated copper in leaching with sulfuric acid, to use the electrolytically 0o precipitated copper with high grade of Sb and Bi, and the like, since each Ssolubility of Sb and Bi in the sulfuric acid-leached solution is constant. The Bi and Sb separated from the electrolytically precipitated copper can be further individually separated and recovered, for example, by treatment in an electric oven.

[0029] Second Step The second step includes addition of trivalent iron to the sulfuric acid-leached solution produced in the first step so as to produce crystalline scorodite (FeAsO 4 r12H 2 and then solid-liquid separation of the solution into a residue containing the crystalline scorodite and a post-dearsenic solution.

[0030] The crystalline scorodite can be produced, for example, by heating to to 95C under atmospheric pressure. For example, a reaction for 8 to 72 hours yields a sufficient amount of the scorodite. Since As has been sufficiently oxidized to pentavalent As in the first step, the crystalline scorodite is produced with trivalent iron at high reaction efficiency. The scorodite is chemically stable, and suitable for long-term storage.

[0031] The trivalent iron includes iron oxide, iron sulfate, and iron chloride.

Preferably, the trivalent iron is provided in the form of acidic aqueous solution since the reaction is conducted in an aqueous solution; and preferably in the form of aqueous ferric sulfate (Fe 2

(SO

4 )3 solution since recycling the post-deironing solution to the electrolyte for electrolytic smelting is the most effective.

Aqueous polyferric sulfate solutions for use in drainage treatment, etc. can also be used. Advantageously, the aqueous solution is added to the sulfuric acid-leached solution such that the leaching solution during addition of the aqueous solution is maintained at a pH of 0.3 to 2.2, and preferably 0.4 to 1.2, from the viewpoint of scorodite production. Since As has been sufficiently 950823 I.DOC -8oxidized to pentavalent As in the first step, scorodite can be readily formed even N at such a low pH. In addition, the pH need not to be increased in this stage, Swhich leads to an advantage of no need for addition of alkaline such as caustic soda. Therefore, the process for treating electrolytically precipitated copper according to the present invention allows for a simple and seamless link between Sthe first step and the second step.

00[0032] The trivalent iron needs to be used in an amount of 1.0 equivalent or Smore based on the amount of As from the viewpoint of As removal, and Npreferably in an amount of 1.1 to 1.5 equivalents from an economic viewpoint.

ic0 [0033] Third Step SThe third step is optionally conducted when the post-dearsenic solution contains unreacted Fe, or unreacted Fe and As. This step includes addition of alkaline to the post-dearsenic solution to produce Fe salts with which As component, if any, is co-precipitated, and then solid-liquid separation of the solution into precipitates containing Fe salts and As component, if any, and a post-deironing solution.

[0034] Any alkaline that can produce insoluble Fe salts (with which As, if any, can be co-precipitate) is used. Such alkalines include, for example, sodium carbonate, calcium carbonate, sodium hydroxide, calcium hydroxide, and magnesium hydroxide.

It is the most advantageous for the smelting step to return the post-deironing solution to the electrolyte for electrolytic smelting. From this point, use of sodium is not preferred due to difficulty of removing from the electrolyte. On the other hand, no strict limitations are placed on use of calcium because it can be removed by forming gypsum with coexistent sulfuric acid. Accordingly, preferred as alkaline are calcium compounds such as calcium carbonate and calcium hydroxide, and especially preferred is calcium carbonate due to its easy pH control.

[0035] Iron hydroxide begins to significantly precipitate at a pH of 2.2 or above, while at a pH of above 4.0, copper is readily precipitated. From the viewpoint of precipitation efficiency of Fe salts and avoidance of precipitating Cu salts, alkaline is preferably added until the pH of the post-dearsenic solution reaches the range of 2.2 to 4.0, and more preferably until the pH becomes in a range of 3.0 to 950S23 1,DOC [0036] This precipitate can be dissolved with sulfuric acid followed by recycling the dissolved material to the second step as an iron source and As, if any, to be treated. The post-deironing solution primarily contains copper sulfate Swith few impurities, and thus can be utilized as electrolyte for electrolytic smelting. However, the subsequent forth step may further recover Cu as Sprecipitate from the post-deironing solution.

00 [0037] Forth Step The forth step is optionally conducted where Cu should be recovered as Nprecipitate, and includes addition of alkaline to the post-deironing solution to precipitate Cu salts, and then solid-liquid separation of the solution into precipitates containing the Cu salts, and a post-decoppering solution. For example, heating at 40 to 70C for 30 to 90 minutes to mature the precipitates is effective for enhancing filterability.

[0038] Any alkaline that can produce insoluble Cu salts is used. Such Is alkalines include, for example, sodium carbonate, calcium carbonate, sodium hydroxide, calcium hydroxide, and magnesium hydroxide. When calcium salts are used, intrusion of gypsum occurs, degrading the quality of copper in the precipitate. Therefore, sodium alkaline is preferably used in order to reduce the precipitate. For cost consciousness, inexpensively available calcium alkaline is preferably used.

Alkaline is preferably added until the pH of the post-deironing solution reaches the range of 4.0 to 8.0, and more preferably until the pH becomes in a range of 5.0 to 7.0, from the viewpoint of precipitation efficiency of Cu salts, alkaline costs, the copper grade in the precipitate, and drainage standards.

[0039] The post-decoppering solution contains mainly calcium or sodium which was used for neutralization, and sulfuric acid radical, with heavy metals removed, and then can be treated as general total drainage.

[Examples] [0040] Now, the following examples will be given for better understanding of the present invention and advantages thereof, but the present invention is not limited to the examples.

Fig. 1 is a flow chart of the treatment according to one embodiment of the present invention.

[0041] Washing Treatment of Electrolytically Precipitated Copper with Water 950823.I.DOC With 2000 ml of water, 1000 g (wet weight) of electrolytically precipitated N copper having a composition shown in Table 1 was repulped, and stirred for four Shours to elute electrolyte (containing copper sulfate, nickel, iron, and so on) adhered during production of the electrolytically precipitated copper, followed by filtering the slurry for solid-liquid separation. The resulting residue was dried, and directed to the first step. The residue weight after drying was 733.2 g.

00 Ni and Fe were found almost completely removed. Table 1 shows the results N together with analytical values for the residue.

[0042] First step: Leaching of electrolytically precipitated copper with io sulfuric acid To 200 g (dry weight) of the electrolytically precipitated copper after the washing treatment above, 228.6 g of 98% conc. sulfuric acid was added (1.1 equivalents based on the copper contained in the electrolytically precipitated copper), and then water was added to adjust the amount of the slurry to 2000 ml (pH before the reaction: 0.07).

Leaching was performed while feeding air at a rate of 700 ml/minute for seven hours with stirring. For air feeding and stirring, a JET AJITER (available from SHIMAZAKI) was used. The solution temperature was not particularly controlled. Since the leaching with sulfuric acid is an exothermic reaction, the temperature increased to 88 0 C four hours after the beginning of leaching, and then gradually decreased to 70C seven hours after. During the reaction, the solution turned black to blue (pH after the reaction: 0.85). After leaching with sulfuric acid, the leached material was filtered for solid-liquid separation. The residue was washed with water, and the wash solution was combined with the sulfuric acid-leached solution. Table 2 shows the amounts in the resulting sulfuric acid-leached solution and the residue after leaching with sulfuric acid.

The amount of the residue indicates that 87.1% of bismuth in the electrolytically precipitated copper was removed as the residue from the leached solution. Only 1.6% of arsenic and 0.4% of copper are present in the residue.

This means the reaction has a high efficiency.

[0043] Second Step: Scorodite Formation To 425 ml of the sulfuric acid-leached solution produced in the first step, 225 ml of a ferric sulfate solution (a solution of 43 g of a ferric sulfate reagent (n-hydrate, the ferric content: 21.3%) dissolved in warm water, 1.45 equivalents of the ferric based on the arsenic contained in the sulfuric acid-leached solution) 950823_I.DOC S-11was added to adjust the amount of the solution to 650 ml, followed by heating to 0 C and carrying out scorodite formation for 24 hours.

SJust after mixing the sulfuric acid-leached solution with the ferric sulfate Ssolution at a room temperature, the reaction did not take place. With heating, precipitation of scorodite was observed at around 60 0 C. The pH of the solution for formation was 0.63 (at room temperature) before the beginning of the reaction, and 0.58 (at room temperature) after the completion of the reaction. After 00 scorodite formation, the scorodite crystal was filtered followed by solid-liquid N separation.

r"- The scorodite crystal was washed with water, and the water used was C combined with the post-dearsenic solution. Table 3 shows the amounts in the resulting scorodite crystal and the post-dearsenic solution. Fig. 2 shows an XRD of the resulting scorodite crystal. Little arsenic was eluted, and stable crystalline scorodite was obtained.

0.2 mg/L of arsenic was eluted from the scorodite obtained through this procedure (TCLP, with acetate buffer solution of pH This proved that the arsenic was stable. The amount of the scorodite crystal indicates that 98.0% of arsenic is distributed in the scorodite crystal, showing a high efficiency of the reaction.

Considering that trivalent arsenic does not contribute to scorodite, leaching of the electrolytically precipitated copper with sulfuric acid converts 98% or more of the eluted arsenic to pentavalent arsenic. This shows that it is effective to use the sulfuric acid-leached solution of the electrolytically precipitated copper as an ingredient for scorodite formation.

[0044] Third Step: Neutralization for Deironing To 1370 ml of the post-dearsenic solution resulted from the second step, 26.6 g of calcium carbonate (10.64 g as Ca) was added to neutralize the solution to a pH of 3.48, and co-precipitate arsenic and iron as iron hydroxide. Then, the precipitate was aged by heating at 60 0 C for 30 minutes in order to enhance filterability. This precipitate included iron hydroxide with co-precipitated arsenic, as well as gypsum formed from calcium carbonate added for neutralization and sulfuric acid radical.

This precipitate was filtered, followed by solid-liquid separation. The precipitate was washed with water, and the water used was combined with the post-deironing solution. Table 4 shows the amounts in the resulting precipitate 9508231 .DOC -12- (hereinafter referred to as "deironing mud") and the post-deironing solution. No arsenic was detected from the post-deironing solution, showing that arsenic was Sefficiently removed. On the other hand, only 0.3% of copper was distributed in Sthe deironing mud, showing that copper remained in the post-deironing solution.

Fig. 3 shows the results when the neutralization for deironing was performed with varying the pH for studying its pH dependence.

[0045] Forth Step: Neutralization for Deironing 00 IN To 2315 ml of the post-deironing solution resulted from the third step, 9.2 g C of calcium carbonate (3.68g as Ca) was added to neutralize the solution to a pH of 5.59, and precipitate as copper hydroxide. Then, the precipitate was aged by C heating at 60 0 C for 30 minutes in order to enhance filterability. This precipitate was filtered, followed by solid-liquid separation. Table 5 shows the amounts in the resulting precipitate (hereinafter referred to as "decoppering mud") and the post-decoppering solution. Copper was highly recovered, and well separated from bismuth and arsenic.

Fig. 4 shows the results when the neutralization for decoppering was performed with varying the pH for studying its pH dependence.

950823 I.DOC 13- [0046] [Table 1] Electrolytically Precipitated Copper (Wet) Amount of 1000.0 Material (Wg) Number of Molecular Grade Moles (mol) Weight 10.5 Electrolytically Precipitated Copper (Dry) Amount of 895.0 Material (Dg) Number of Molecular Grade Moles (mol) Weight As 26.0 3.11 74.92 Fe 0.05 0.01 55.85 Oa 62.0 8.73 63.55 Sb 2.4 0.18 121.76 Bi 0.26 0.01 208.98 N 0.84 0.13 58.69 Pb 0.09 0.00 207.21 Q_ <0.01 40.08 Si cI 0. 03 0.00 60.09 S 8.5 2.37 32.07

I

4 Precinitated Connner (Drv Washina Treatment with Watei I Amount of Material (Dg) Number of Molecular Grade Moles (mol) Weight As 31.0 3.03 74.92 Fe <0.01 0.00 55.85 ai 66.0 7.61 63.55 Sb 2.7 0.16 121.76 Bi 0.31 0.01 208.98 N 0.28 0.03 58.69 Pb 0.28 0.01 207.21 Ch <0.01 40.08 Si C 0.03 0.00 60.09 S 0.51 0.12 32.07 Treatment with Water

I

Amount of Material (ml) 3060 Number of Molecular Grade Moles (mol) Weight As 0.13 0.01 74.92 Fe 0. 15 0.01 55.85 C1i 6.70 0.32 63.55 Sb 0.02 0.00 121.76 Bi 0.03 0.00 208.98 N 2.50 0.13 58.69 Pb <0.01 0.00 207.21 C 40.08 Si Ce <0.01 0.00 60.09 S 10.33 0.99 32.07 950823 I.DOC -14- [0047] [Table 2] Residue after Washing Electrolytically Precipitated Copper with Water (Dry) Amount ol Material (Dg) 2 Number of Molecular Grade Moles (mol) Weight As 31.0 0.828 74.92 Fe <0.01 55.85 Ou 66.0 2.077 63. 55 Sb 2.7 0.044 121.76 Bi 0.31 0.003 208.98 N 0.28 0.010 58.69 Pb 0.28 0.003 207.21 Ca <0.011 40.08 Si C2 0.03 0.001 60.09 S 0.51 0.032 32.07 H12SOt 98.07 98% Sulfuric Acid (adding 1.1 equivalents to copperlj Amount of Material (g) Number of Molecular Grade Moles (mol) Weight As __74.92 Fe 55.85 Oa 63.55 Sb 121.76 Bi 208.98 N -_58.69 Pb 207.21 Ca 40.08 SiO 60.09 S 9832.07 1-1SOl 98.0 2.28 98.07

IV-

Leaching with Sulfuric AcidEOOg/IlO0 'hrs,air70Dml/min (JET AJITER~j Amount of 2000 Material (ml) Number of Molecular Grade (g/Il) Moles (mol) Weight As 31.0 0.828 74.92 Fe 55.85 Cu 66.0 2.077 63. Sb 2.7 0.044 121.76 Bi 0. 3 0.003 208.98 N 0.3 0.010 58.69 Pb 0.3 0.003 207.21 C- 40. 08 Si C2 0.0 0.001 60.09 S 148.6 2.316 32.07 H2SO4 112.0 2.284 98.07 t, Residue after Leaching with Sulfuric Acid (Dry) Amount of 8. 3 Material (Dg) Number of Molecular Grade Moles mol) Weight As 11.0 0.012 74.92 Fe 0.00 55.85 Cu 6.7 0.009 63.55 Sb 28.0 0.019 121.76 i 6.90 0.003 208.98 N 0. 00 0.000 58.69 Pb 17.00 0.007 207.21 Ch 40.08 Si C2 1. 10 0.002 60.09 S 1.40 0.004 32.07 HWS1 0 I 98. 07 nffl. Sulfuric Acid-Leached Solution Amount of 2840 Material (ml) Number of Molecular Grade Moles (mol) Weight As 20.00 0.758 74.92 Fe 0.00 0. 000 55.85 OC 50.00 2.234 63.55 Sb 0.90 0.021 121.76 Bi 0.03 0.000 208.98 N 0.20 0.010 58.69 Pb 0.01 0.000 207.21 a 0.000 40.08 Si C5 0.00 0.000 60.09 S 24.00 2.125 32.07 H2SO 17.20 0.498 98.07 950823_1.DOC [0048] [Table 3] Sulfuric Acid-Leached Solution pHi .03 Amount of42 Material (ml)42 Grae (/1)Number of Molecular Grae (il)Moles (mol) Weight AS 20.00 0. 113 74.92 Fe 0.00 0.000 55.85 GU 50.00 0.334 63.551 Sb 0.90 0.003 121.76 0.03 0.000 208.98 Pb 0.01 0.000 207.21 0. 000 40. 08 S 24.00 0.318 32.07 22.99 Scorodite Production pH=0.63E]95F Oj 2hr Amount Material Grae (/1)Number of Molecular Grae (il)Moles (mol) Weiaht ,AS 13.08 0. 113 74.92 Fe 14. 07 0. 164 55. GU 32.69 0.334 63.55 Sb 0.59 0.003 121.76 R0.02 0.000 208.98 Pb 0.01 0.000 207.21 Ca 0. 00 1 0. 000 40. 08 S27.81 0.564 32.07 EE]h 0. 00 0. 000 22. 99 Ferric Sulfate (n-hydrateoi Amount of Material 43. 0 Grade Number of Molecular (mol) Weight T- AS 0.00___ T- Fe 21.26 0. 164 55. 0.00___ Sb S 18. 31 0.246 32.07 0.00 ni-n ~R Scorodite Crytal Amount of 2.

Material (Dai)269 Gae()Number of Molecular Gae()Moles (mol) Weiaht AS 27.00 0.097 74.92 Fe 23.00 0. 111 55. 85 a 1.20 0.005 63.55 Sb 1.30 0.003 121.76 Bi0.04 0.000 208.98 Pb 0.00 0.000 207.21 Ca 0. 00 0. 000 40. 08 S 1.20 0.010 32.07 0. 00 0. 000 122. 99 Post-Dearsenic solution Amount of 18 Material (ml) 18 Gae(/)Number of Molecular Grae (il)Moles (mol) Weight AS 0. 10 0.002 74. 92 Fe 2.20 0.058 55. CU 12.00 0.279 63. .Sb 0.01 0.000 121.76 B0.00 0.000 208. 98 Pb 0. 00 0. 000 207. 21 Ga 0. 00 0. 000 140. 08 S12.00 0.554 320 0.0 0 .001 F 2-2. 991 950823_1L)OC 16- [0049] [Table 4] Post-Dearsenic Solution Amount of Material (ml) 1480 Grae (/1)Number of Molecular Grae (il)Moles (mol) Weight As 1 0. 10 0. 002 74. 92 Fe 2.20 0.058 55. CU 12.00 0.279 63.55 Sb 0.01 0.000 121.76 a0.00 0.000 208.98 Pb 0.00 0.000 207.21 Ca0. 00 0. 000 40. 08 S 12.00 0. 554 32.07 0.01 001 2.99 1370/1480ml C aC 03 10.64 g(Ca) Deironing Mud Amount of 4.

Material (Dg) 466 Grad (%)Number of Molecular Grae %)Moles (mol) Weight As 0. 30 0. 002 74. 92 Fe 6.20 0.052 55. 85 CU0. 12 0. 001 63. 55 Sb 0.04 0.000 121.76 Bi 0.00 0.000 208.98 Pb 0.00 0.000 207.21 Ca 20.00 0. 233 40.08 S 16.00 0.232 32.07 0. 00 0. 000 22. 99 pH-3.48 Post-Deironing Solution Amount of 22 Material (ml1) 242 Grae (/1)Number of Molecular Grae (/l)Moles (mol) Weight As 0.00 0.00 74.92 Fe 0.01 0.00 55. 6.80 0.26 63. Sb 0.00 0.00 121.76 0.00 0.00 208.98 Pb 0.00 0.00 207.21 0.49 1 0.03 40.08 S3. 80 0.29 32.07 0.01 0.001 22.99 950823J DOC -17- [0050] [Table Post-deironing Solution Amount of 2425 Material (ml) Numberof Molecular Grade (g/I) Moles (mol) Weight As 0.00 0.00 74.92 Fe 0.01 0.00 55.85 Cu 6.80 0.26 63.55 Sb 0.00 0.00 121.76 Bi 0.00 0.00 208.98 Pb 0.00 0.00 207.21 Ca 0.49 0.03 40.08 S 3.80 0.29 32.07 Na 0.01 0.001 22.99

I

2315/24251 CaC03 pH559 368 gCa) Decoppering Mud Amount of 58.2 Material (Dq) Number of Molecular Grade Moles (mol) Weight As 0.00 0. 000 74.92 Fe 0.05 0.001 55.85 Ci 27.00 0.247 63.55 Sb 0.00 0.000 121.76 Bi 0.00 0.000 208.98 Pb 0.00 0.000 207.21 Ch 14.00 0.203 40.08 S 12.00 0.218 32.07 N 0. 00 0.000 22.99 4 Post-Vecoppering Solution Amount of 2990 Material (ml) 2 Number of Molecular Grae Moles (mol) Weight As 0.00 0.00 74.92 Fe 0.00 0.00 55. Cu 0.00 0.00 63.55 Sb 0.00 0.00 121.76 Bi 0.00 0.00 208.98 Pb 0.00 0.00 207.21 Ca 0.58 0.04 40.08 S 0.47 0.04 32.07 Ni 0.00 0. 000 22.99 [0051] [Fig. 1] Fig. 1 shows a flow chart of the treatment according to an embodiment of the present invention.

[Fig. 2] Fig. 2 shows an XRD of the scorodite crystal produced in Examples.

[Fig. 3] Fig. 3 shows pH dependence of neutralization for deironing.

[Fig. 4] Fig. 4 shows pH dependence of neutralization for decoppering.

9508231 .DOC

Claims

2. The process according to claim 1, wherein the leaching with sulfuric acid in the first step includes stirring at 70 to 95 0 C for 4.5 to 11 hours.
3. The process according to claim 1 or 2, wherein the leaching with sulfuric acid in the first step is conducted without external heating.
4. The process according to any one of claims 1 to 3, wherein the oxygen-containing gas in the first step is air. The process according to any one of claims 1 to 4, wherein the feeding and/or stirring of the oxygen-containing gas in the first step is performed through jetting.
6. The process according to any one of claims 1 to 5, wherein the sulfuric acid-leached solution in the first step has a pH of 0.3 to 2.2. 950823 .DOC -19- S7. The process according to any one of claims 1 to 6, wherein the Nleaching with sulfuric acid in the first step oxidizes 95 wt.% or more of the As Scomponent to pentavalent As.
8. The process according to any one of claims 1 to 7, wherein the crystalline scorodite in the second step is produced by heating to 60 to 95 0 C.
9. The process according to any one of claims 1 to 8, wherein the trivalent iron in the second step is provided as ferric sulfate. 00
1110. The process according to any one of claims 1 to 9, wherein the Ncrystalline scorodite in the second step is produced at a pH of 0.4 to 1.2. 11. The process according to any one of claims 1 to 10, wherein the (alkaline in the third step is added until the pH of the post-dearsenic solution reaches the range of 2.2 to 12. The process according to any one of claims 1 to 11, wherein the alkaline in the forth step is added until the pH of the post-deironing solution reaches the range of 4.0 to 13. The process according to any one of claims 1 to 12, wherein the alkaline in the third step and/or the forth step is provided as calcium carbonate. 14. A process for treating electrolytically precipitated copper, which process is as defined in claim I and substantially as herein described with reference to Figs. 1 to 4. Electrolytically precipitated copper treated by the process of any one of claims 1 to 14. DATED this Twentieth Day of September, 2007 Nippon Mining Metals Co., Ltd. Patent Attorneys for the Applicant SPRUSON FERGUSON 950823) 1.DOC