JPS6115133B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to the recovery of metals, and in particular to the recovery of gold, silver, nickel or copper metal values. A method for recovering the above metals from a carrier in which they are adsorbed as a complex is disclosed in Japanese Patent Application No. 49-49.
It is disclosed in the specification of No. 135004 (Japanese Unexamined Patent Publication No. 84417/1983). According to this method, valuable metal components are desorbed by bringing the carrier into contact with water having a low concentration of metal cations. Preferably, the water has a low multiply charged cation (eg alkaline earth metal cation) concentration.
Concentrations below 300 ppm, preferably 50 ppm are preferred. In other words, water is relatively pure and has low ionic strength. Suitable water is, for example, distilled water, deionized water and soft water. Any suitable adsorbent carrier may be used in the above method which has special application for metal values in the form of cyanide ion-bound complexes, where the metal values form the anionic component of the complex. is possible,
Carbon, especially activated carbon, is preferred. Especially when the complex is a gold cyanide complex, when the cation of the complex is an alkaline earth metal,
It is also disclosed that the complex is more strongly adsorbed on the support than when the cation is an alkali metal. Therefore, the cation of the complex is an alkaline earth metal,
Particularly in the case of calcium, it is preferred to pre-treat the support with an alkali metal salt solution before water desorption. This pretreatment results in an exchange reaction between the alkali metal and the alkaline earth metal. The exchange reaction is enhanced by providing a salt in which the anion forms an insoluble or substantially insoluble salt with the alkaline earth metal such that the latter is effectively removed from the system as the exchange occurs. be done. Suitable salts for this purpose are carbon salts, oxalates, sulphites and fluorides; the alkali metals are preferably sodium, potassium or lithium. The preferred pretreatment solution according to the above patent is basic.
Potassium carbonate/potassium hydroxide solution with pH. We have now discovered that improved results can be obtained with other pretreatment solutions. According to the invention, the carrier is contacted with a solution selected from the group of alkali metal cyanide solutions, alkali metal hydroxide solutions and mixtures thereof, and the metal values are subsequently retained in water with a low concentration of metal cations. A carrier having one or more metal values adsorbed in the form of an alkaline earth metal ion-bound complex in which the metal values form part of the anionic component, including a step of desorption from the body. from,
A method for recovering valuable metals selected from gold, silver, copper and nickel is provided. The solution may contain a concentration of alkali metal cyanide within the range of 1 to 10% by weight and an alkali metal hydroxide concentration within the range of 1 to 20% by weight. Preferably, the concentration of cyanide ions is greater than the concentration of hydroxyl ions in the solution. A preferred mixture is sodium cyanide and sodium hydroxide. A particularly suitable pretreatment solution contains an alkali metal cyanide concentration of about 10% by weight and an alkali metal hydroxide concentration of about 1% by weight. Another suitable pretreatment solution is sodium hydroxide solution. It has been found that concentrations not exceeding 10% by weight give satisfactory results. Initially, the metal components are adsorbed onto the support in the form of alkaline earth metal ion-bound complexes. A preferred carrier is activated carbon. After treatment of the support with the chosen solution, desorption is carried out using conditions and water as described in the above and above-mentioned patents. It is important to point out that the desorption process only involves physical adsorption/desorption functions and not ion exchange. The alkaline earth metal is generally calcium;
And the complex is generally a cyanide ion-bound complex. The present invention involves the preparation of gold-containing ores from solutions containing gold and other metal values obtained by cyanidation treatment of gold-containing ores with, for example, sodium cyanide/calcium hydroxide leaching solutions such as those described in the patents mentioned above. There are special applications for the extraction of valuable metals. The invention is illustrated by the following examples. Example 1 Type G210 using gold factory curing method after spill
Granular activated carbon [Le Carbon (Putey) company {Le
Carbone (Pty) Lta}]. The analysis results of the loaded activated carbon were as follows. Gold 2.9 kg/ton Silver 64 g/ton Nickel 2.2 kg/ton Copper 90 g/ton These metals are present on activated carbon in the form of calcium cyanide ion-bound complexes, e.g. Ca(Au(CN) ₂ ) ₂ was. The initial capacity constant of the virgin activated carbon was 22 mg gold/g activated carbon. Various operations were performed using different pretreatment solutions and operating conditions. Unless otherwise noted, 16 g of activated carbon was packed into a small glass elution column using a vibrator in each case, with an inner diameter of 1 cm and a length of 25
cm activated carbon bed was prepared. After some excess water begins to flow out of the column, 1/2 of the treatment solution is pumped through the bed at a rate of about 1 bed volume per hour (apparent flow rate 9.2 x 10 ^-3 cm/sec).
The bed volume was pumped to pre-treat the bed. The pretreatment was then eluted using 90°C deionized water at an elution rate ranging from 0.5 to 2.0 bed volumes per hour. Ten bed volumes were then collected and analyzed. Finally, the activated carbon was removed from the column, dried in an oven, analyzed, and tested for activity. In all the experiments performed, the pretreatment solution consisted of a mixture of sodium cyanide and sodium hydroxide. (a) Operations 1 to 11 The first series of experiments investigated the effects of changing the relative proportions of these two components. The results of these experiments are shown in Tables 1 and 2 below.

【table】

[Table] As the concentration of sodium hydroxide is decreased and the concentration of sodium cyanide is increased, the recovery rate of metal values is improved, and the best results are obtained at 10% by weight of sodium cyanide and 1% by weight of sodium hydroxide. It can be seen that the results were obtained using a pretreatment solution consisting of: (b) Runs 12 to 14 In the second series of experiments (Runs 12 to 14), the efficiency of the process with respect to high gold loading was studied. The results are shown in Table 3. G215 activated carbon was loaded with 4-6% gold using clarified gold mill concentrate solution. The metal values in the solution were in the form of cyanide ion-bound complexes. Loaded activated carbon was treated with various sodium cyanide/sodium hydroxide reagents and
Elution was performed with deionized water at 90°C. In Operation 12, the analytical values of the loaded activated carbon were 4% gold, 600 g/ton silver, and 2600 g/ton nickel. Pretreatment solution is sodium cyanide 10
%/14% sodium hydroxide. Money
A recovery rate of 98.6%, 83% for silver, and 99% for nickel was obtained. After treatment with 6 bed volumes of deionized water (12 hours), the gold eluate contained only 6 g/ton of gold. In Operation 13, the analytical values of the loaded activated carbon were 6% gold, 2000 g/ton silver, and 6000 g/ton nickel. Pretreatment solution is sodium cyanide 12
%/1% sodium hydroxide. Money
A recovery rate of 99.9%, silver 97.1% and nickel 99.9% was obtained. Lower concentrations of hydroxide appear to give better results. Similar results were obtained in Operation 14, but the activated carbon analysis values in this case were 4% gold, 1000 g/ton silver, and 1700 g/ton nickel.

【table】

[Table] (c) Operations 15 to 17 In the third series of experiments, the method of the invention was combined with the other two methods, namely potassium carbonate pretreatment and then 90%
A comparison was made between elution with deionized water at 65°C and sodium sulfide/sodium hydroxide solution at 65°C. The results are shown in Table 4 below and illustrated in Figures 1 (gold), 2 (silver) and 3 (nickel).

[Table] It can be seen that the method using sodium cyanide/sodium hydroxide pretreatment is superior to the other two methods. In the case of gold recovery, Na ₂ S/NaOH is replaced by NaCN/
gives slightly better recovery than NaOH, but
The discomfort of handling Na ₂ S/NaOH and its cost make it unacceptable as a pretreatment reagent. No by-products precipitate on activated carbon.
Recovery is close to 100%. Since the regenerated sodium cyanide and sodium hydroxide solutions can be reused in other parts of the gold circuit, the cost of the reagents is relatively low and the elution requires only 5 to 7 bed volumes of eluent at 90°C, or 125 It is flexible in that it can be performed at a rate of 1/2 to 1 bed volume per hour (elution time 3 hours) at 4 to 5 bed volumes at °C, and the higher the gold loading on the activated carbon, the more ,
Improves elution efficiency. Example 2 In this example, the effect of using a sodium hydroxide pretreatment solution was studied. The methods and materials used were similar to those used in Example 1. As in Example 1, the concentrated solution of metal was a cyanide effluent from a gold extraction process. Various sodium hydroxide solutions were studied and the results of these studies can be found in Table 5. From these results it can be seen that no effective benefit can be obtained using concentrations of sodium hydroxide higher than 10% by weight. It should also be pointed out that in all of steps 18-21, the loaded activated carbon was acid washed with hydrochloric acid to remove calcium carbonate from the carbon before being treated with sodium hydroxide.

【table】

【table】 [Brief explanation of the drawing]

Figures 1, 2 and 3 show the elution of gold, silver and nickel adsorbed on activated carbon using the method of the present invention and other methods, namely the potassium carbonate/potassium hydroxide method and the sodium sulfide/potassium hydroxide method. This is a graph comparing the elution status with the method using sodium hydroxide. Figure 1 is gold, Figure 2 is silver, Figure 3 is gold, Figure 3 is silver,
The figure is a graph for Nickel. Curve A in Figures 1, 2, and 3 is 3% Na ₂ S/3% NaOH at 65°C (Table 4, step 16), and curve B is 10% NaCN/3% NaOH at 90°C. 1% NaOH
(Table 4, operation 17), curve C is 10% K ₂ CO ₃ /5 at 90°C.
Figure 2 is a graph showing the test results for %KOH (Table 4, step 15).

Claims (1)

[Claims] 1. A carbonaceous support in which a metal component is adsorbed in the form of an alkaline earth metal cyanide ion complex forming a part of the anion component is brought into contact with a pretreatment solution, and then A method for recovering gold, silver, copper or nickel valuables by desorbing metal valuables from the carrier with water containing a low concentration of metal cations, wherein the pretreatment solution comprises alkali metal cyanide, A method for recovering metal valuables, characterized in that the solution is selected from the group consisting of alkali metal hydroxides and mixtures thereof. 2. The first above, wherein the solution contains an alkali metal cyanide at a concentration within the range of 1 to 10% by weight, and an alkali metal hydroxide at a concentration within the range of 1 to 20% by weight.
The method described in section. 3. The method according to item 2 above, wherein the concentration of cyanide ions is higher than the concentration of hydroxyl ions. 4. The method according to item 2 or 3 above, wherein the solution contains sodium cyanide and sodium hydroxide. 5. The method according to item 1 above, wherein the solution is a sodium hydroxide solution with a concentration not exceeding 10% by weight.