KR20020022856A - Effective recovery of valuable metals from wasted metal tailings, wasted printed circuit boards or low-graded metal stones - Google Patents

Abstract

PURPOSE: An economical and environmental friendly method for recovering valuable metals is provided which effectively recovers valuable metals such as gold, silver, copper and zinc from waste ore tailings, waste printed circuit boards or low-graded ore is provided, and prevents environmental contamination at the same time. CONSTITUTION: The method for recovering valuable metals from waste ore tailings, waste printed circuit boards or low-graded ore comprises the steps of adsorbing gold, silver, copper and zinc on the resin by passing cyanide leaching solution of waste ore tailings, waste printed circuit boards or low-graded ore through a cation exchange resin; recovering gold/silver metals by adding copper powder to the extracted solution containing gold/silver ions after extracting gold/silver adsorbed in the resin using a solution containing Cu(CN)2¬-1 ions as an extractant; and recovering copper/zinc metals by solvent extracting and electrolyzing the extracted solution after extracting copper/zinc adsorbed into the resin using as an extractant a mixed solution in which H2O and H2O2 are mixed with the gold/silver constituent removed resin.

Description

EFFECTIVE RECOVERY OF VALUABLE METALS FROM WASTED METAL TAILINGS, WASTED PRINTED CIRCUIT BOARDS OR LOW-GRADED METAL STONES}

The present invention relates to a method for efficiently recovering valuable metals from waste tailings, waste printed circuit boards, or low grade ores, and specifically, from the cyanide leaching solution of waste tailings, waste printed circuit boards or low grade ores by using a specific extractant. The present invention relates to an economical and environmentally friendly waste resource recycling method for efficiently recovering valuable metals such as silver, copper, and zinc, and recovering and reusing cyanide.

At present, most of the tailings or low-grade ore of waste mines in our country are left untreated, and heavy metals (As, Cr, Cd, Pb, Hg, Mn, Cu, Zn, Fe, etc.) and cyanide that can be eluted from them. (CuCN) and the problem of environmental pollution by acidic water is emerging. The tailings or ore also contains a large amount of valuable metals (gold: 1-3 g / t, silver: 1-10 g / t, copper: 10-150 g / t, zinc: 10-200 g / t). Although it is not known that gold or silver can be economically processed from ore containing a large amount of copper or zinc (more than 50g per ton), the existing mine reclamation project can be applied to their cover and landfill without creating substantial added value. It depends.

Meanwhile, in South Africa, Russia, the United States, Australia, etc., a method of recovering valuable metals from tailings or low-grade ores using resins has been steadily studied. Extracting gold / silver first using Zn (CN) ₄ ^2- as the following and then recovering copper / zinc using NaOH and NaCN as the extractant is most widely used.

However, in the above method, even if the gold / silver adsorbed on the resin is extracted for 24 hours at a temperature of 50 ° C., the extraction rate is only about 60%, and a large amount of gold is extracted during the subsequent extraction of copper / zinc. Has the disadvantage of being lost.

Thus, the present inventors used a mixed solution of H ₂ SO ₄ and H ₂ O ₂ A solution containing Cu (CN) ₂ ^-1 as a result of continued extensive studies, the gold / silver extracting agents, as extractants of copper / zinc The present invention has been completed by discovering that valuable metals such as gold, silver, copper and zinc can be efficiently recovered from the cyan leaching liquid of waste tailings, waste printed circuit boards or low-grade ores for a short time at room temperature.

An object of the present invention is to provide an economical and environmentally friendly valuable metal that can efficiently recover valuable metals such as gold, silver, copper, and zinc from waste tailings, waste printed circuit boards, or low-grade ores and prevent environmental pollution. It is to provide a recovery method.

1 is a schematic recovery process diagram of a valuable metal according to the method of the present invention,

Figures 2a and 2b is a graph showing the change of the content of gold and silver dissolved in the extract according to the gold / silver extraction (or substitution) time in the embodiment, Figure 2c is an extract according to the copper / zinc extraction time in the embodiment Is a graph showing the change of the content of gold, silver, copper and zinc dissolved in the

Figure 3a is a graph showing the change of the content of cyanide dissolved in the extract according to the cyanide recovery time in the embodiment, Figure 3b is a graph showing the change of the content of cyanide dissolved in the extract according to the cyanide oxidation time in the comparative example .

In the present invention to achieve the above object,

(1) Cyan leaching liquid of waste tailings, waste printed circuit board or low grade ore is passed through cation exchange resin to adsorb gold, silver, copper and zinc to resin;

_{(2) Cu (CN) 2} -1 ion is extracted by using the extraction agent for the gold / are adsorbed to the resin-containing solution, the gold / copper powder is added to the ion-containing extract gold / silver, and recovering the metal,

(3) The copper / zinc adsorbed on the resin was extracted using a mixed solution of H ₂ SO ₄ and H ₂ O ₂ as a extractant on the resin from which the gold / silver component was removed, and then the solvent was extracted and electrolyzed. Comprising recovering the zinc metal,

Provided are methods for recovering valuable metals from waste tailings, waste printed circuit boards, or low grade ores.

Hereinafter, the present invention will be described in more detail.

A schematic recovery process diagram of a valuable metal according to the method of the present invention is shown in FIG. According to Figure 1, the cyan leaching liquid of the waste tailings, waste printed circuit board or low-grade ore is passed through a cation exchange resin to adsorb the various ions eluted in the leaching liquid to the resin, and then the gold / silver is first extracted and recovered from the resin and then copper / Extract and recover zinc.

Adsorption of the eluted ions to the resin in the cyan leaching solution made by immersing the object in a cyan solution such as NaCN is represented by the following Scheme 1, where R means resin:

Na ²⁺ Au (CN) ₂ ^-1 , Cu (CN) _x ^x-1 , Ag (CN) ₂ ^-1 , Zn (CN) ₄ ^2- + R-SO ₄ ^2-

¡Æ R-Au (CN) ₂ ^-1 , Cu (CN) _x ^x-1 , Ag (CN) ₂ ^-1 , Zn (CN) ₄ ^2- + Na ₂ SO ₄

As the cation exchange resin, a conventional one can be used, and it is usually used in the form of a column.

Then, as shown in the following scheme 2, in accordance with the gold / extract recovery process of the present invention, it is passed through the Cu (CN) ₂ ^-1 ion-containing solution with the resin is extracted with gold / silver.

R-Au (CN) ₂ ^-1 , Cu (CN) _x ^x-1 , Ag (CN) ₂ ^-1 , Zn (CN) ₄ ^2- + Cu (CN) ₂ ^-1

¡Æ R-Cu (CN) _x ^x-1 , Zn (CN) ₄ ^2- + Au (CN) ₂ ^-1 + Ag (CN) ₂ ^-1

The gold / silver extraction recovery process may be carried out by passing a solution containing Cu (CN) ₂ ^-1 ion of 0.1 to 2M at room temperature over 6 to 16 hours. Cu (CN) ₂ ^-1 ion containing solution is simple, by a method of adding a copper powder in a NaCN solution or mixture of CuCN and NaCN solution, the solution may be prepared by conventional. Subsequently, an excess of copper powder corresponding to 10 to 20 times the amount of gold and silver was added to the obtained extract, and gold / silver cyanide (Au (CN) ₂ ⁻¹ and Ag (CN) ₂ ⁻¹ ) was added. The mixture of gold and silver metal can be recovered in solid form by cementation of silver ions with copper ions. The recovered metal mixture can be separated into gold and silver metal, respectively, by reacting with nitric acid to selectively dissolve silver. Further, the resulting Cu (CN) ₂ ^-1 solution of gold / silver is reused as extractant. On the other hand, since a large amount of unsubstituted copper powder remains in the extracted extract after the recovery of the gold / silver metal, copper is further dissolved by further adding H ₂ SO ₄ and an oxidizing agent (eg, H ₂ O ₂ ) to the copper. Can be recovered as copper metal in the zinc recovery process.

In the copper / zinc extraction recovery process of the present invention following the gold / silver extraction recovery process, copper / zinc is extracted by passing a mixed solution of H ₂ SO ₄ and H ₂ O ₂ through the resin, as shown in Scheme 3 below.

R-Cu (CN) _x ^x-1 , Zn (CN) ₄ ^2- + H ₂ SO ₄ + xH ₂ O ₂

¡Æ Cu ²⁺ SO ₄ ^2- + Zn ²⁺ SO ₄ ^2- + HCN (gas) + H ₂ O

The copper / zinc extraction recovery process may be performed by passing a mixed solution of H ₂ SO ₄ and H ₂ O _{2 in} a molar ratio of 1: 0.1 to 0.2 over 0.5 to 3 hours at room temperature. Subsequently, the obtained CuSO ₄ and ZnSO ₄ containing extracts may be recovered by solvent extraction and electrolysis according to a conventional method, and each of the copper and zinc metals may be recovered, and various heavy metals adsorbed on the resin may also be selectively removed. The resulting H ₂ SO ₄ solution will also be reused as a copper / zinc extractant.

As can be seen from Scheme 3, HCN, a contaminant during copper / zinc extraction, is produced in gaseous form. Conventionally, the cyanide produced is oxidized and removed, but since a large amount of oxidizing agent is required for oxidation, in the present invention, the produced HCN gas is reacted with NaOH solution again as in Scheme 4 below to recover in the form of NaCN and waste tailings. Recycled as a solvent for waste printed circuit boards or low grade ore cyanide leaching solutions.

HCN (gas) + NaOH → NaCN (liquid) + H ₂ O

On the other hand, the cyan leaching liquid (tailing liquor) after the resin adsorption process, as shown in Scheme 5 below, is re-passed through the resin in the middle of the gold / silver extraction and copper / zinc extraction process to completely remove the cyan ions and then the CN concentration to the environment It can be discharged by removing below the reference value.

^{_{R-Cu (CN) 2 -1}} , Zn (CN) 4 2- + R-SO 4 2- + 2Na + CN -

≧ R-Cu (CN) _x ^x-1 , Zn (CN) ₄ ^2- + Na ₂ SO ₄

According to the valuable metal recovery method of the present invention, the high-quality gold and silver, including copper and zinc, for about a short time at room temperature from the cyan leaching liquid of waste tailings, waste printed circuit board or low-grade ore, or waste-rock storage leachate, Not only can it be recovered with little loss, but it can also efficiently remove harmful substances such as heavy metals and cyanide, which can solve economic and environmental pollution.

Hereinafter, the present invention will be described in more detail based on the following examples. However, the following examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

Example

Gold, silver, according to the recovery process of the present invention shown in Figure 1 using a standard mixed metal compound solution (solvent is NaCN) containing gold, silver, copper and zinc at 2, 10, 40 and 7 mg / L, respectively Recovery of copper and zinc was performed. After passing the standard mixed metal compound solution through 50 g of a cation exchange resin Dowex (Sigma Chemical Corporation), the amount of gold, silver, copper and zinc contained in the resin was measured to be 3.46, 17.3, 32.2 and 8.05 g / kg.

After passing 500 mL of 0.5 M Cu (CN) ₂ ^-1 ion-containing aqueous solution through the resin at 25 ° C. for 12 hours, 20 g of copper powder was added to the solution that passed through the resin and stirred to prepare a mixture of gold and silver metal. Recovered in the form. The recovered metal mixture was reacted with nitric acid to dissolve silver, and gold and silver metal were separately recovered. Subsequently, 2L of a mixed solution of 5% H ₂ SO ₄ and 4 g / LH ₂ O ₂ was passed through the resin at 25 ° C. for 2 hours, and the solution passed through the resin was then extracted from the LIX series (Henkel). ) And then electrolyzed to recover each of the copper and zinc metals. In addition, HCN gas generated during copper / zinc extraction was collected, reacted with NaOH solution, and recovered in the form of NaCN.

The recoveries and recoveries of gold, silver, copper and zinc are shown in Table 1 below, and the changes of the amounts of gold and silver dissolved in the extract according to the gold / silver extraction (or substitution) time are shown in FIGS. 2A and 2B. The change of the contents of gold, silver, copper and zinc dissolved in the extract with the copper / zinc extraction time is shown in FIG. 2C. In addition, the change of the content of cyanide dissolved in the extract according to the cyanide recovery time is shown in Figure 3a.

Extractant Recovery g / kg (% recovery) Copper zinc gold silver Cu (CN) ₂ ^-1 4 hours - - 2.664 (77) 8.05 (100) 12 hours - - 3.391 (98) - H ₂ SO ₄ + H ₂ O ₂ 1 hours 30.01 (93.2) 17.3 (100) 0.014 (0.4) - 2 hours 32.2 (100) - 0.017 (0.5) -

As can be seen from Table 1 and FIGS. 2A to 2C, according to the method of the present invention, gold and silver can be recovered more than 98% in 12 hours of gold / silver extraction, and copper and zinc in 2 hours of copper / zinc extraction. 100% zinc can be recovered with little loss of gold and silver. In addition, from Figure 3a, according to the method of the present invention, it can be seen that the cyanide which is a harmful substance is also 100% removed within a short time.

Comparative example

In recovering gold, silver, copper and zinc by the same method using the standard mixed metal compound solution and the cation exchange resin used in the above example, 0.5M Zn (CN) ₄ ^2- at 50 ° C. during gold / silver extraction. A solution containing 4 g / L NaOH and 50 g / L NaCN was passed through the resin for 24 hours at 50 ° C. during the copper / zinc extraction and the excess of HCN gas generated during the copper / zinc extraction. It was removed by oxidation with H ₂ O ₂ .

The recovery and recovery rates of gold, silver, copper, and zinc were as shown in Table 2 below, and the change in the amount of cyanide dissolved in the extract according to cyanide oxidation time is shown in FIG. 3B.

Extractant Recovery g / kg (% recovery) Copper zinc gold silver Zn (CN) ₄ ^-2 6 hours 1.932 (6) 1.211 (7) 1.384 (40) 4.83 (60) 24 hours 2.576 (8) 1.73 (10) 2.145 (62) 6.04 (75) NaOH + NaCN 3.5 hours 21.6 (67.2) 12.11 (70) 0.296 (8.6) 0.733 (9.1) 24 hours 24.5 (76.2) 14.71 (85) 0.298 (8.6) 0.83 (10.3)

As can be seen from Table 2, according to the conventional method, it can recover only about 62% of gold and silver during 24 hours of gold / silver extraction at 50 ° C., and copper and zinc even during 24 hours of copper / zinc extraction at 50 ° C. Only 76% of this is recovered, resulting in significant losses of gold and silver. 3b, it can be seen that only about 50% of cyanide can be removed by the conventional method.

According to the valuable metal recovery method of the present invention, the high-quality gold and silver, including copper and zinc, for about a short time at room temperature from the cyan leaching liquid of waste tailings, waste printed circuit board or low-grade ore, or waste-rock storage leachate, Not only can it be recovered with little loss, but it can also efficiently remove harmful substances such as heavy metals and cyanide, which can solve economic and environmental pollution.

Claims (8)

(1) Cyan leaching liquid of waste tailings, waste printed circuit board or low grade ore is passed through cation exchange resin to adsorb gold, silver, copper and zinc to resin; _{(2) Cu (CN) 2} -1 ion is extracted by using the extraction agent for the gold / are adsorbed to the resin-containing solution, the gold / copper powder is added to the ion-containing extract gold / silver, and recovering the metal, (3) The copper / zinc adsorbed on the resin was extracted using a mixed solution of H ₂ SO ₄ and H ₂ O ₂ as a extractant on the resin from which the gold / silver component was removed, and then the solvent was extracted and electrolyzed. Comprising recovering the zinc metal, A method for recovering valuable metals from waste tailings, waste printed circuit boards or low quality ores. The method of claim 1, Gold / Silver extraction, characterized in that a solution containing 0.1 to 2 M of Cu (CN) ₂ ^-1 ion is passed through the resin for 6 to 16 hours. The method of claim 1, Gold / silver method characterized by using the Cu (CN) ₂ ^-1 solution generated during the metal recovery of gold / silver extraction agent again. The method of claim 1, H ₂ SO ₄ and an oxidizing agent are added to the remaining extract after gold / silver metal recovery to dissolve the remaining copper powder, and then combined with the extract obtained in step (3) to use for recovery of copper / zinc metal. The method of claim 1, A method for producing a copper / zinc extraction, wherein the mixed solution of H ₂ SO ₄ and H ₂ O _{2 in} a 1: 0.1 to 0.2 molar ratio is passed through the resin for 0.5 to 3 hours. The method of claim 1, HCN gas generated during copper / zinc extraction is reacted with NaOH solution to recover in the form of NaCN and reused as a solvent for waste tailings or low grade ore cyanide leaching solution. The method of claim 1, Using H ₂ SO ₄ solution generated during copper / zinc recovery as a copper / zinc extractant. The method of claim 1, In the middle of the gold / silver extraction and copper / zinc extraction process, the cyan leaching solution after the resin adsorption step is passed through the resin to completely remove the cyan ions in the leaching solution and discharged.