FI66911B - FOERFARANDE FOER UTFAELLNING AV METALLCEMENT UR EN LOESNING SO TILLSATTS ETT UTFAELLNINGSMEDEL - Google Patents

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Federal Republic of Germany-Förbunds republi ken Tyskland (DE) P 2540100.7 Proven-Styrkt (71) Klöckner-Humboldt-Deutz Aktiengesellschaft, Deutz-MOlhelmer-Str. Ill, 5000 Cologne 80, Federal Republic of Germany-Förbundsrepubliken Tyskland (DE) (72) Ernst Kausel, Lima, Peru (PE), Reinhard Nissen, Cologne, Federal Republic of Germany-Förbundsrepubliken Tyskland (DE) (74) Antti Impola (54) Method for precipitating metal 1 cement from a solution to which a precipitant has been added - Method for precipitating metal cement from a solution to a finishing agent

The invention relates to a method for eatering metal cement from a solution to which a precipitant has been added, applying a method for eaafering copper cement from a copper solution to which iron bodies have been added, wherein the copper cement deposited on the iron bodies is continuously removed by moving the iron bodies and removed from the solution.

When an metal is alloyed as a metal cement from a solution of this metal to which a base metal has been added as a precipitant, there is a so-called In the context of “cementation”, regardless of which metals are involved in each case, it is always a matter of substantially similar events, in which, according to the voltage series, ion exchange occurs between the nobler and the nobler metal.

The term "cementation" is defined in Lexikon der Hiittäni echnik von Mger, 4 ·. Auflage 1963, Band 3, Deutsche Verlaganstalt Stuttgart, page 733 as follows: ‘’ Alloying of metal from solution by means of a base.

The potential of the base metal is more negative than that of the metal to be alloyed and releases positively charged ions into the solution, thus negatively charging itself and discharging all cations with more positive potentials. The separation takes place in a metallic form. The decisive factor is therefore the potential difference between the different cations under the prevailing conditions. ” 2,66911

In connection with the most different methods of cementing or precipitating metals, there are fundamental difficulties due to the fact that the precipitated metal, the so-called cement metal, covers the surfaces of the base metal used as a precipitant and thus prevents or even interrupts the electrochemical reaction, i.e. ion exchange. Other obstacles to the reaction are due to the formation of either an oxide layer on the surface of the metallic precipitant or the formation of a coating of fine gas bubbles from electrolytic events.

The object of the invention is therefore to overcome these difficulties known in all kinds of precipitation processes and thus to improve both the economy and the metal recovery and thus the overall efficiency of the process.

The invention is based on the application of a method for precipitating copper cement from a copper solution to which iron bodies have been added, wherein the copper cement deposited on the iron bodies is continuously removed by moving the iron bodies and removed from the solution from which the copper is to be removed. The invention is characterized in that the method is used for arbitrary other wet metallurgical processes for precipitating arbitrary metals as metal cements from their solutions to which a more noble electrochemically negative metal has been added as a metal precipitant, the metal bodies being vibrated at such a frequency that these metal particles are continuously impacted.

A preferred embodiment of the invention is based on the application of zinc wet metallurgy to precipitate a noble metal relative to zinc, e.g. Cu, Cd, Co, Ni, as a metal cement from a zinc solution to which zinc metal bodies have been added as a precipitant.

A preferred variant of the invention is based on the fact that the method is applied to precious metal-wet metallurgy, e.g. for precipitating silver or gold as a metal cement from their cyanide solution, to which zinc bodies have been added as a precipitant.

A pendulum mill is then suitably used as the precipitation reactor.

The invention and the technological and economic advantage which can be obtained therefrom over the prior art will be explained in more detail on the basis of a representative use example selected from zinc wet metallurgy.

In zinc wet metallurgy, the neutral broths hitherto conventionally formed have been purified of foreign metals dissolved therein, e.g. Cu, Cd, Co or Ni, by adding metallic zinc powder to the broth in mixers, so that said impurities precipitate.

However, this known method has the particular disadvantage, 3 6691 1, that zinc powder must first be prepared, e.g. by spraying metallic zinc. Moreover, the reaction between the precipitating powder and the broth takes place extremely slowly, so that the reaction takes up to several hours, especially because an immunizing zinc oxide layer forms on the zinc particles, which decisively prevents the reaction from continuing.

In contrast to this prior art, the invention instead proceeds to add zinc in pieces to the broth instead of zinc powder, e.g. 2 ... 10 mm granules, and to carry out the whole precipitation process using a pendulum mill as a precipitating reactor to continuously develop the desired strong strike each other.

Due to the strong vibration movement of the zinc bodies, the invention thus provides in a simple and efficient manner that the surfaces of the zinc bodies coated with the noble metal precipitate become continuously impacted and rubbed clear and so that these surfaces remain active for continuous ion exchange reaction.

In addition, the strong vibration movement of the precipitation reactor and the metal bodies causes a strong turbulence in the broth. Thus, thorough mixing of the solid and liquid phases in the boundary layer is achieved. As a result, the ion concentration in the surface area of the precipitant will be considerably higher than when applying previously known precipitation methods, which further accelerates the metabolism. In addition, the hydrogen sulfide liberated as a result of the reaction is emulsified in a fine bubble in the broth and can thus considerably improve the effect as a reducing agent.

Thanks to the invention, an economical effect is achieved, for example, in zinc wet metallurgy, so that instead of expensive zinc powder, cheap zinc waste and intermediate products can be used as a precipitant, e.g. shards, slags from roasting process, etc. which are only in part metallic zinc. Until now, such wastes have had to be smelted to separate zinc, so that the wastes can be returned to the zinc leach and dissolved there.

All such expensive treatment steps become unnecessary and can be omitted when, according to the invention, not expensive zinc powder is used for precipitation, but slag, waste, granules or other granular metal particles in a vibrating tank.

Due to the forced vibration of the precipitation reactor, the contents of this reactor acquire such a high energy potential that the zinc bodies are exposed to .. i \; 4 6691 1 in continuous strong motion and strike and rub against each other. In this case, their surfaces remain free of impurities or immunizing coatings, be they oxides, metal-cement deposits or the formation of gas bubbles, which results in an accelerated metabolism due to the ion exchange between the metal and the solution.

This will ultimately lead to a considerable shortening of the process and, in addition, to a better utilization of the metal material used, as the consumption of the metal will be reduced to an approximately stoichiometric value, while this consumption in a conventional precipitation drum can be up to 500% of the stoichiometric amount.

The technological possibilities and economic advantages obtained as an example of the zinc wet metallurgy used are, in principle, valid for other applications of the process in virtually all arbitrary cementation processes in the field of wet metallurgy.

The invention will be explained in more detail below on the basis of some application examples, in which case two cementation examples according to the current state of the art are compared with two precipitation-treatment examples according to the invention.

1) Example of performing precipitation according to the current state of the art

The broth contains, as a solution, metal compounds obtained from complex iron ore by chlorinating evaporation in the following amounts; 23 g / l Ousaj 3 g / l Fe: aj 80 g / l Zmaj 1 g / l Fb} 1 g / l As: aj the rest Bi, Co, Cd Ag about 200 mg / 1.

A precipitating drum with a volume of about 100 m 2 is filled with about 30 jd? broth with dissolved metals. The precipitating drum is a pear-shaped, acid-resistant lined container rotatable about its axis. In addition to the broth, about 50 tons of iron scrap is placed from the top opening. At about 30 ° C, the cartridge is agitated for about 120 minutes by rotating the vessel. The result is a final broth with about 380 mg / l copper. The scrap consumption of this discontinuous process is about 215% of the stoichiometric amount of iron.

2) Example of conventional cementation:

Neutral dissolution in zinc metallurgy gives a neutral broth which, in addition to the dissolved zinc oxides, contains varying amounts of dissolved ions of electrochemically nobler metals, in particular Cutn, Ni, Co and Cd. These foreign metals, which are considered to be impurities in relation to the zinc metal to be taken, must be alloyed with the broth, since even very low concentrations of these metals have a very detrimental effect on the subsequent electrolysis of zinc.

These metallic impurities are doped with zinc dust because said impurities are more positive than electrochemical than the cementing agent. The cementation is suitably carried out in stages so that the fractions obtained from the cementate can be further processed accordingly.

The cementation is carried out discontinuously in a mixing vessel, in which case zinc dust is added in batches. The broth introduced into the vessel contains 150 g / l Sins «} 500 mg / l Cu 400 mg / l Cd 20 mg / l Niiaj 20 mg / 10 0o.

In the first step, the broth is subjected to a precipitation treatment at 95 ° C with the addition of zinc dust, copper sulphate and arsenic trioxide, whereby Co, Cu, Ni and As are cemented, while Cd remains dissolved.

The processing times for both cementing steps are about 260 minutes. Zinc dust consumption is 550% of the stoichiometric theoretical amount of zinc.

Result

The purified neutral liquor contains the following amounts of residual impurities: Cu 0.1 mg / l, Co 0.2 mg / l, Ni 0.05 mg / l, Cd 0.2 mg / l.

3) Example of cementation according to the invention:

The copper solution of the neutral broth of the oxide copper ore concentrate is cemented using scrap iron as a precipitant. The cementation is carried out in a test apparatus by means of a pendulum mill, the speed and amplitude of which can be adjusted. The reactor is a heated satellite connected to a pendulum mill and having a filling volume of 8.5 dm ^. The filling of the cementing agent is 65% of the reactor volume, i.e. 5.5 dm ^, and the amount of broth is 45% of the reactor volume, i.e. 3 dm ^.

Cementation of copper from a copper sulphate solution by means of iron stamping waste begins at a copper content of 36 g / l. The diameter (amplitude) of the oscillation circle is 10 mm, and the oscillation frequency is 12.5 Hz. The processing temperature is 18 ° C and the processing time is 180 sec. The analysis shows a residual copper content of 40 mg / l.

When the parallel test is carried out under exactly the same conditions, but using a treatment temperature of 63 ° 0, a residual concentration of 40 mg / l of copper is reached after only 32 seconds.

6 6691 1

In both cases, the consumption of scrap iron corresponds to 1.2 times the stoichiometric amount of iron.

4) Example of aementation according to the invention;

Using the same experimental reactor, copper is cemented with a pendulum mill using a neutral broth of zinc using zinc granules. The amount of dissolved copper at the beginning of the reaction is about 500 mg / l of copper when the amount of zinc is 150 g / l · The treatment temperature is 95 ° C and the pH of the broth is 4. The grain size of the zinc granules used as filler is in the range of 5 ... 10 mm. The oscillation is performed with an amplitude of 10 mm And at a frequency of 12.5 Hz. After a cementation treatment of as little as 29 seconds, the analysis shows that the final copper content is less than 0.1 mg / l copper.

The invention includes other applications of the principle of the method to arbitrary other treatments of cementation reactions in the field of wet metallurgy, provided that they fall within the scope of the following claims.

A '1

Claims (3)

6691 1 7 A method for precipitating a metal cement from a solution to which a precipitant has been added using a method for precipitating a copper element from a copper solution to which iron bodies have been added, wherein the copper as mental cements from their solutions to which a more precious electrochemically negative metal has been added as metal pieces as a precipitant, these metal pieces being vibrated at such a frequency that these metal pieces are continuously struck against each other. Process according to Claim 1, characterized in that the process is used in zinc wet metallurgy for precipitating a metal nobler than zinc, e.g. Cu, Cd, Co, Ni, etc., as a metal cement from a zinc solution to which zinc metal bodies have been added as precipitating melt. . Process according to one of Claims 1 to 2, characterized in that a pendulum mill is used as the precipitation reactor.