A greener gold production from both primary and secondary resources

Good news!

"An interdisciplinary team of experts in green chemistry, engineering and physics at Flinders University in Australia has developed a safer and more sustainable approach to extract and recover gold from ore and electronic waste. ..."

"The glistening gold-extraction technique, ... promises to reduce levels of toxic waste from mining and shows that high purity gold can be recovered from recycling valuable components in printed circuit boards in discarded computers. ...

Around the world, artisanal and small-scale gold miners use mercury, which binds to gold particles in ores, to create what are known as amalgams. These are then heated to evaporate the mercury, leaving behind gold but releasing toxic vapours. Studies indicate that up to 33% of artisanal miners suffer from moderate metallic mercury vapor intoxication. ...

“The study featured many innovations including a new and recyclable leaching reagent derived from a compound used to disinfect water,”  ...

“The team also developed an entirely new way to make the polymer sorbent, or the material that binds the gold after extraction into water, using light to initiate the key reaction.” ..."

"... A final innovation is to recycle the sorbent. Here we relied on a linear poly(trisulfide) that can be “un-made” by depolymerization. This capability allows simultaneous gold recovery and monomer recycling. We are particularly proud of developing this polymer because it was originally thought to be inaccessible. Our photo-chemical polymerization in a flow reactor overcame this challenge to provide that key material. ..."

From the abstract:

"Gold plays an essential role in the global economy and has wide applications in various industrial technologies.

Currently, the gold supply relies heavily on mining processes that employ toxic substances such as cyanide salts and mercury metal, leading to substantial environmental pollution.

Gold extraction approaches that do not rely on cyanide and mercury are needed to improve the overall sustainability of gold production.

Here we develop an approach for gold leaching and recovery from ore and electronic waste. This approach first uses trichloroisocyanuric acid, activated by a halide catalyst, to oxidatively dissolve gold metal from ore and electronic waste, and then applies a polysulfide polymer sorbent to selectively bind gold from the leachate.

The gold can be recovered in high purity by pyrolysing or depolymerizing the sorbent. The efficacy of this approach in gold extraction was validated using ore, electronic waste and other gold-containing waste. Overall, this work provides a viable approach to achieve greener gold production from both primary and secondary resources, improving the sustainability of the gold supply."

Gold from e-waste opens a rich vein for miners and the environment

Golden opportunity to reduce toxic waste (original news release)

Sustainable gold extraction from ore and electronic waste "Our team has developed a sustainable method for gold extraction. Our goal is to reduce the impact of gold mining on the environment and human health, providing safer alternatives to cyanide and mercury in mining."

Sustainable gold extraction from ore and electronic waste (no public access)

Mali Seizes 3 Metric Tonnes of Gold from Canadian Mining Company Barrick

Bad news! I don't think this was a very smart move by the new military junta!

Arbitrary expropriation by a government usually does not end well!

Decade-low tariff to boost Indian gold consumption in festive season

Gold news! And what about rubies?

"The value more than doubled compared to the same month a year ago, and tripled from $3.1 billion in July, according to data from India's commerce ministry."

Decade-low tariff to boost Indian gold consumption in festive season - Nikkei Asia "World's second biggest consumer imports record $10bn of gold in August"

Earthquakes produce giant gold nuggets by electrifying quartz to make “natural batteries”

Amazing stuff! Turns out again, earth quakes are not entirely destructive! 😊

Will there be a new gold rush after the next earthquake? Just kidding!

"... To test this hypothesis, researchers conducted an experiment designed to replicate the conditions quartz might experience during an earthquake. They submerged quartz crystals in a gold-rich fluid and applied stress using a motor to simulate the shaking of an earthquake. After the experiment, the quartz samples were examined under a microscope to see if any gold had been deposited.

“The results were stunning,” ... “The stressed quartz not only electrochemically deposited gold onto its surface, but it also formed and accumulated gold nanoparticles,”  ..."

From the abstract:

"Gold nuggets occur predominantly in quartz veins, and the current paradigm posits that gold precipitates from dilute (<1 mg kg−1 gold), hot, water ± carbon dioxide-rich fluids owing to changes in temperature, pressure and/or fluid chemistry. However, the widespread occurrence of large gold nuggets is at odds with the dilute nature of these fluids and the chemical inertness of quartz. Quartz is the only abundant piezoelectric mineral on Earth, and the cyclical nature of earthquake activity that drives orogenic gold deposit formation means that quartz crystals in veins will experience thousands of episodes of deviatoric stress. Here we use quartz deformation experiments and piezoelectric modelling to investigate whether piezoelectric discharge from quartz can explain the ubiquitous gold–quartz association and the formation of gold nuggets. We find that stress on quartz crystals can generate enough voltage to electrochemically deposit aqueous gold from solution as well as accumulate gold nanoparticles. Nucleation of gold via piezo-driven reactions is rate-limiting because quartz is an insulator; however, since gold is a conductor, our results show that existing gold grains are the focus of ongoing growth. We suggest this mechanism can help explain the creation of large nuggets and the commonly observed highly interconnected gold networks within quartz vein fractures."

Earthquakes produce giant gold nuggets by electrifying quartz to make “natural batteries” "New research suggests that electricity generated by earthquakes might be the key to the formation of giant gold nuggets."

Electricity generated by earthquakes might be the secret behind giant gold nuggets (original news release)

Gold nugget formation from earthquake-induced piezoelectricity in quartz (no public access)

Tether Announces New Synthetic Dollar a USDT That’s Backed by Gold

Good news! The golden years of digital currency are about to begin! (just kidding)

"Alloy by Tether designed to track dollar with gold collateral

Tether Gold has a $573 million market capitalization ..."

"Tether, the largest company in the cryptocurrency industry, is excited to announce the official launch of Alloy by Tether, a ground-breaking tethered asset backed by Tether Gold. Developed by Moon Gold NA, S.A. de C.V. and Moon Gold El Salvador, S.A. de C.V., both of whom are members of the Tether Group, Alloy by Tether aims to redefine stability in the digital economy by combining the strengths of a stable unit of account with the security and reliability of gold. ..."

Tether Announces New Synthetic Dollar aUSDT That’s Backed by Gold - Bloomberg

Tether Announces Launch of Alloy by Tether: A New Digital Asset Backed by Tether Gold (original news release) 

Gold Made Easy XAUt is a digital token, backed by physical gold.

435 Tonnes of African Gold Lost to Smuggling largely to the UAE in 2022 with Palki Sharma

Bad news! 

Ukraine's Soldiers are Fighting Russia in the Sudan War with Palki Sharma

As if the Russo-Ukrainian War is not already a World War III! What a story!

Gold rush in Mauritania

Recommendable!

Graphene efficiently recovers gold from waste electronics

Good news! One man's trash is another woman's treasure! A new gold rush cometh? 😄

This new approach seems to be very selective!

"Discarded electronics can be a gold mine – literally. Researchers have developed an efficient new way to use graphene to recover gold from electronic waste, without needing any other chemicals or energy. ...
First the e-waste is ground up, then dissolved in a solution. A membrane made of reduced graphene oxide is added, and within a few minutes pure gold begins to accumulate on the membrane surface. Just 1 gram of graphene is enough to extract almost twice that amount of gold, attracting over 95% of the gold in a given sample even at concentrations as low as one part per billion. Importantly, it doesn’t attract other metals in the e-waste mixture, and afterwards the graphene membrane can be burned off, leaving behind the pure gold. ..."

From the abstract:

"Materials capable of extracting gold from complex sources, especially electronic waste (e-waste), are needed for gold resource sustainability and effective e-waste recycling. ... Here we report an approach based on reduced graphene oxide (rGO) which provides an ultrahigh capacity and selective extraction of gold ions present in ppm concentrations (>1000 mg of gold per gram of rGO at 1 ppm). The excellent gold extraction performance is accounted to the graphene areas and oxidized regions of rGO. The graphene areas spontaneously reduce gold ions to metallic gold, and the oxidized regions allow good dispersibility of the rGO material so that efficient adsorption and reduction of gold ions at the graphene areas can be realized. By controlling the protonation of the oxidized regions of rGO, gold can be extracted exclusively, without contamination by the other 14 co-existing elements typically present in e-waste. These findings are further exploited to demonstrate recycling gold from real-world e-waste with good scalability and economic viability, as exemplified by using rGO membranes in a continuous flow-through process."

Graphene efficiently recovers gold from waste electronics

Highly efficient and selective extraction of gold by reduced graphene oxide (open access)

Fig. 4: Flow-through technology for gold extraction and recycling

Gold: Denn aller Wert will Ewigkeit

Empfehlenswert! Eine umfassende und gelungenen Beschreibung der Geschichte und Wissenschaft vom Gold in einem nicht zu langen Artikel!

Gold: Denn aller Wert will Ewigkeit