Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Gold without poison

25.02.2008
Researchers from the Krasnoyarsk State University together with their colleagues from the Institute of Chemistry and Applied Chemistry, Siberian Branch, Russian Academy of Sciences, also located in Krasnoyarsk, have developed an original method for extracting gold and silver from multicomponent solutions.

The peculiarity of the suggested technology is that chemists have ultimately managed to find an adequate and fundamentally less toxic replacement to cyanide – the reagent which is widely applied for extracting gold from ore and recyclable materials and which is even called a “poisonous companion of gold”. It is the very poison the detective story authors like so much but river and lake inhabitants dislike so much.

They dislike it to such extent that they simply die – this happened, for example, to fish in the Danube, when in 2000 cyanide got into the Tisa river and then from it – into the Danube through a small Austrian gold-mining company’s fault. The company used cyanide to extract gold and silver from solutions. However, not only fish suffered – a lot of birds and wild animals died, millions of Hungary inhabitants were deprived of drinking water.

Basically, the method developed by the Krasnoyarsk chemists does not differ fundamentally from the known one. In both cases, the reagent is added to complicated solutions containing a noble metal– for example, after ore dissolution, or as the specialists put it, opening up of ore. The reagent forms a complex both with gold and silver. Thus a compound is obtained, in which the central atom of the metal is surrounded by several ions – either those of cyanide (as usual), or of thiocyanate (a new method).

The entire construction is an anion, and it can be further extracted from the solution on the so-called ion-exchanging column – chlorine ions can be “changed” (they go into the solution) for composite ions that contain the noble metal in the ion-exchange resin filling the column.

Then these ions, certainly together with silver and gold should be washed off the column, and the target metal should be educed from this solution – it can be reduced electrolytically or by any other method.

However, this seems simple only on paper. But in real life chemists had to perform tremendous work to select the most efficient sorbent and conditions of dealing with it to “catch” maximum noble metal from the solution and then to wash all of it off the column, it is desirable to do that separately. And they have succeeded in doing that.

The researchers not only investigated the sorbtion mechanism of thiocyanate complexes of gold and copper on very different sorbents, but they also discovered those that enable to extract practically all noble metal from the solution. Moreover, having designed the necessary methodology, the authors learned to fully separate gold and silver, varying the solution composition, which “washes off” the target metal from the sorbent. Besides, the researchers developed and patented the method that allows to determine the gold content directly in the sorbent, but not in a ready solution. Of course, this is very convenient – because this allows to learn exactly how fully the noble metal was extracted from the initial solution and then – how fully it was extracted from the sobent.

In brief, the researchers have developed an excellent method for extracting gold and silver – it is efficient and much less poisonous the traditional method. Cyanide is almost one hundred times more toxic than thiocyanate. So, the Krasnoyarsk chemists have managed to relieve gold at least one poisonous companion – cyanide.

Olga Myznikova | alfa
Further information:
http://www.informnauka.ru

More articles from Ecology, The Environment and Conservation:

nachricht Value from wastewater
16.08.2017 | Hochschule Landshut

nachricht Species Richness – a false friend? Scientists want to improve biodiversity assessments
01.08.2017 | Carl von Ossietzky-Universität Oldenburg

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>