DE2125542B2 - PROCESS FOR EXTRACTION OF SILVER AND GOLD FROM DILUTED SOLUTIONS - Google Patents

Description

As has been shown, silver and / or gold can be obtained using the method according to the invention from very dilute solutions of their salts or else gain from their solutions. For example, it is possible to use 1 g of silver or a smaller amount, contained in a solution weighing one tonne. The at the Application of the method according to the invention required relative movement between the adsorbent the solution, from which silver and / or gold are to be recovered, can be made simple Way to achieve that after the introduction of the adsorbent substance into the solution, the solution is shaken for a few minutes. Instead, it is also possible to use a slurry of the adsorbent Substance in the solution from which silver and / or gold are to be recovered, in motion keep. It is also possible to use the solution in itself known way to flow through with the adsorbent substance.

Loading takes place in a relatively short time, i. H. in about 20 to 30 minutes for silver and in an insignificantly longer period of time with gold. To take full advantage of the adsorbent, it is easily possible to carry out the process according to the invention in several stages. That happens in such a way that the adsorbent does not when performing the aforementioned process has been fully loaded is used again to perform the procedure. This can happen several times in a row. To make the method according to the invention as economical as possible to carry out, it is completely sufficient that the weight of the adsorbent introduced into the solution about 80 ° ο of the silver contained in the solution or gold. As it turned out. 1 kg of potassium hexacyanocobaltoferrate is capable of about 1.25 kg Enrich silver from solutions of silver salts. 1 kg of Berlin blue are made according to the procedure deposited according to the invention about 1.2 kg of silver.

A very expedient measure for separating the silver or gold of the adsorbent material is that od for separating these metals with silver or gold loaded adsorbent in a quartz vessel using a high-frequency furnace. Like. To about 1500 ^c C with stirring and then about not dripped silver is secreted by means of a vibrator or an ultrasonic device in a manner known per se. When it is heated, the quartz vessel is expediently surrounded by a tantalum sheet or placed in a gold bath.

Another very advantageous measure is that when using potassium hexacyanocobaltoferrate for separating silver or gold with the dissolved metal loaded adsorbent in an amount whose weight is 1 g, in an aqueous KCN solution with a concentration ratio of 2 g KCN is dissolved in 5 ml of water, then the solution formed in this way is heated to about 40 to 60 ° C and kept at this temperature until the solution takes on a clear yellow-brown color. 5- diluted to 2 times volume, cooled and treated with a solution of 5 g Na ₂ S · 9HJ added ₁ O in 5 ml of water, heated for a period of about 10 minutes at 60 to 8O ⁰ C, filtered the silver sulfide thus formed hot, washed with water and roasted at a temperature of 800 to 900 ^{c C.}

Another advantageous measure is that when using beriiner blue for separation of the metal of the adsorbent loaded with silver or gold, the loaded adsorbent in one Amount the weight of which is 1 g in a KCN aqueous solution having a concentration ratio of 2 g of KCN dissolved in 5 ml of water and increased to 40 bis

ίο heated to 60 ⁰ C and kept at this temperature until the solution takes on a cloudy dark brown color, the solution is then cooled with water to 1.5 to 2 times the volume, the Fe (OH) _{3 formed is} filtered off and is then rewashed with the same volume of water, whereupon the silver sulfide formed is precipitated in a further process step by means of a solution of 5 g of Na, S · 9H ₂ O in 5 ml of water at a temperature of 60 to 80 ^{° C.} , filtered off hot, washed with water and roasted at a temperature of 800 to 900 ° C.

The advantages of the method according to the invention are that the pH of the solutions from

where silver or gold are to be recovered, in all solutions occurring in the industrial sector without any influence on the deposition of the silver and of gold is. The solutions can therefore be neutral to strongly acidic without this Process according to the invention is influenced. As has also been shown, it continues to have no influence on the recovery of the silver and or gold if the solutions in which these metals are dissolved contain numerous other metal ions.

Finally, a particularly great advantage is that the adsorbents used are commercially available are available very cheaply.

1st embodiment

There were 100 mg of potassium hexacyanocobaltoferrate for 20 minutes with a waste solution of 1 ml shaken. The loaded potassium hexacyanocobaltoferrate was then washed with water and then the amount of silver absorbed radiometrically by comparison determined with standard solutions.

This resulted in the conditions set out in the following list

5 ^u the silver recording also given in this list.

minor
55 silver Besides Ag contained the
Solution a mixture of
Ca, Cu, Zn, Cd, Pb.
Fc nitrates of 1 mole each pH Inclusion of Ag
by potassium
Hexacyano
cobalt ferrate
( ¹ Y _n ) 10 ³
6o 10- »
to- = '
Ί0- ³ 10 '
ίο->
ΙΟ " ³
ίο- ³ neutral
1.7
neutral
1.7 100
100
94
98.4

If the separation and recovery of the adsorbed silver, as indicated above, A3s sulfide and made by Röslen, so it was found that the silver obtained in this manner contained less than l ° / ₀ cobalt.

2nd embodiment

100 mg of Prussian blue were shaken with a waste solution containing silver for 20 minutes. The loaded Berlin blue was then washed with water and then washed the amount of silver absorbed radiometrically determined by comparison with standard solutions.

This resulted in the conditions set out in the following list the silver pick-up also given in this list.

minor
silver Besides Ag contained the
Solution a mixture of
Ca, Cu. Zn, Cd. Pb
Fe nitrates of mol / 1 each pH Inclusion of Ag
by
Berlin blue ίο- ³
ΙΟ " ³
10 " ³
io- ³ ίο- ¹
ίο- ¹
ίο- ³
ΙΟ " ³ neutral
1.7
neutral
1.7 100
100
97
98.7

If the Berlin blue laden with silver was treated further as above, it was found that the resulting silver contained less than 1% iron.

Claims (5)

is washed with the same volume of water according to patent claims, whereupon in a further process stage by means of a solution of 5 g of NajS-9H, O in 5 ml of water at a temperature of 60 to 1. Process for obtaining silver or 5 8O ⁰ C precipitates the suber sulfide formed, hot gold scraped off from solutions of these metals or the salts, washed with water and with These metals, in particular from diluted ones, are roasted at a temperature of 800 to 900 ° C Solutions, characterized in that, that a silver or gold salt adsorbing Substance such as ammonium or metal hexacyanoio cobaltoferrate, in particular potassium hexacyanocobaltoferrate, iron hexacyanoferrate, such as Berliner Blue or the like, in such an amount in the dilute solution is introduced that the The invention relates to a method for Weight of the substance to be adsorbed, which is contained in 15 wins of silver or gold from solutions of this solution, corresponds, this being metals or the salts of these metals, in particular in such a way that the solution and adsorber from dilute solutions. This method should make it possible for silver and / or gold to stand relative to one another over a predetermined period of time, whereupon the silver or gold deposited on the silver and / or gold-containing wastewater, sludge adsorbent can be recovered from or other industrial waste.
the adsorbent is separated. This is done according to the previously known 2 The method according to claim 1. thereby driven either electrolytically or in that indicates that the weight that goes into the solution on this waste initially metallic copper introduced adsorbent can act about 80 ° "des in or iron in the form of metal wool. Solution contained silver or gold amounts. »5 being used to purify what is obtained in this way 3. The method according to claim 1 or 2, silver electrolysis is used. This thereby characterized in that known processes for separating are in particular in combination with these Metals laden with silver or gold have been developed with the photography industry. Be adsorbent in a quartz vessel by means of a kannt is also a method for the extraction of High frequency furnace or the like to about 1500 ° C 30 pure silver, after which the silver chloride is heated with soda and then, for example, is not yet melted, and the sodium drips that occur in the process Silver can be washed out by means of a vibrator or a chloride and the soda. These Ultrasonic apparatus in known methods, however, require a behaviorally isolated will. nism moderately high economic outlay. 4. The method according to claims 1 and 2, 35 is the object of the method according to the invention characterized in that when using it, therefore, a process for the extraction of silver of potassium hexacyanocobaltoferrate for separating from dilute solutions. Leaching, sludge nen \ on silver or gold with the dissolved metal or the like to create that in a simple and very vortex-laden Adsorbent in an amount whose economic mode is feasible even then. if wichn is 1 g, in an aqueous KCN solution 40 the content of the residues to be obtained with a concentration ratio of 2 g KCN metals is very low. to 5 ml of water is dissolved, then this object is achieved according to the invention in which the solution thus formed is heated to about 40 to 60 "C process of the above-mentioned type, heated and kept at this temperature for so long that a silver - or gold salts adsorbent until the solution takes on a clear yellow-brown color such as ammonium or metal hexacyanocobaltoferrate, the solution then with in particular potassium hexacyanocobaltoferrate, iron-water to 1.5 to 2 times the volume of hexacyanoferrate Like Berlin blue or the like, in thin, cooled and mixed with a solution of 5 g of such an amount in the diluted solution-Na ₂ S-9H ₂ O in 5 ml of water, for which it is brought that the Weight of the adsorbing duration of about 10 minutes to 60 to 80 ^c C 50 substance about the weight of the heated substance to be adsorbed, the super sulphide hot substance formed thereby, which is contained in the solution ash and at which this happens in such a way that the solution and a temperature of 800 to 900 ⁰ C roasted adsorbent is relative to each other for a predetermined time, whereupon the 5. The method according to claims 1 and 2, 55 deposited silver or gold from the adsorbent characterized in that adsorbent is separated when used. of Prussian blue for separating the metal The potassium hexacyanocobaltoferrate used in the method according to the invention from the adsorbent loaded with silver or gold is a combination of the loaded adsorbent in an amount. plex salt of the approximate composition, the weight of which is 1 g, in an aqueous KCN- 60 K ₂ / FeCo (CN) _e . This salt is extremely be-solution with a concentration ratio of constant and is dissolved by hydrochloric acid, nitric acid and 2 g of KCN to 5 ml of water and is not attacked on 40 to highly concentrated alkalis. It is heated to 60 ° C and, as has been shown, does not decompose at this temperature until the solution takes on a cloudy, dark boiling concentrated hydrochloric acid or nitric brown color, followed by the solution. It can be purchased commercially, ßend with water to 1.5 to 2 times the volume. This also applies to the diluted after another variant, cooled from the Fe (OH) ₃ formed in the process according to the invention is filtered off and then Berlin blue on it.