Technology  

Apart from being treasured for its own essential purity and beauty, and being a global standard of value, gold is used in many electronics for its conductivity and resistance to tarnishing. Gold continues to be mined worldwide, but producers are looking to more sustainable technologies as they extract and process this precious resource.

There are three steps that are involved in the making of all minerals for current industrial and commercial applications—gold included. These include exploration, mining, post mining and production. These three components of the process tend to overlap most of the time. With time, many advances have been made in the world of mining and it keeps getting better each day. Below are some of the changes that are taking the sector by storm.

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Reef Boring Technology

This is a technology that makes it possible for new ore to be tapped from old mines. Not only is the method a simpler way to extract gold, but it is also the best way to improve the sustainability of the gold mines. When commenting on the development of this technology, AngloGold Ashanti Limited, the third largest gold producer stated that they could increase the life of their mines in South Africa by up to 30 years. The method is automatic, which means that it will cut down on labor costs and there will be the possibility of mining being done round the clock.

Fumeless Refining

There have been increasing concerns about environmental sustainability and the mining. Fumeless smelting is a technology that condenses the process of gold smelting into one simple step. As a result:

• No toxic fumes are produced during the smelting process
• There is a reduced amount of toxic waste coming from the smelting process.
• It brings in the possibility of no acids used in smelting.

The possibility of smelting gold without creating any toxic waste is made a reality by this process.

Did you know?
There are about 10 troy ounces of gold (or about three-fifths of a pound) per ton of smartphones on the planet.

Wohlwill Processing

One of the main challenges that come from the gold smelting process is the possibility of getting a purity of more than 99 percent with a single step smelting and processing. With this invention, it will be possible to get up to 99.9 percent pure gold with a one-step purification process. The step gold refining systems will make it possible to get extremely high grade of gold. Luckily there is tons of equipment, like that from Ceramic Technology Inc. to help make gold processing as easy as possible.

Improved Electrolytic Gold Refining

The electrolytic refining system makes it simpler to remove any impurities that could be in the gold. The process of refining gold has always been tedious and involved many steps. However, with the new process, it has become much simpler to clean up the gold with a one step process. By simply immersing the gold you want refined in the system and adding nitric acid, you will get all the impurities out.

The world of gold smelting and refining is bound to get better with these technologies. Not only will smelting be simpler, but it will also be green. It will be really cool to see how it continues to advance in years to come.

By  Kara Masterson

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 Nanotechnology  

By turning Earth’s superabundance of carbon dioxide — a greenhouse gas — into fuel or other useful industrial chemicals we could both counteract the Greenhouse Effect, and create new sources of energy and materials. Now, researchers from Brown have shown that finely tuned gold nanoparticles can do the job. The key is maximizing the particles’ long edges, which are the active sites for the reaction.

By tuning gold nanoparticles to just the right size, researchers from Brown University have developed a catalyst that selectively converts carbon dioxide (CO2) to carbon monoxide (CO), an active carbon molecule that can be used to make alternative fuels and commodity chemicals.

“Our study shows potential of carefully designed gold nanoparticles to recycle CO2 into useful forms of carbon,” said Shouheng Sun, professor of chemistry and one of the study’s senior authors. “The work we’ve done here is preliminary, but we think there’s great potential for this technology to be scaled up for commercial applications.”

The findings are published in the Journal of the American Chemical Society.

The idea of recycling CO2 — a greenhouse gas the planet current has in excess — is enticing, but there are obstacles. CO2 is an extremely stable molecule that must be reduced to an active form like CO to make it useful. CO is used to make synthetic natural gas, methanol, and other alternative fuels.

Converting CO2 to CO isn’t easy. Prior research has shown that catalysts made of gold foil are active for this conversion, but they don’t do the job efficiently. The gold tends to react both with the CO2 and with the water in which the CO2 is dissolved, creating hydrogen byproduct rather than the desired CO.

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The Brown experimental group, led by Sun and Wenlei Zhu, a graduate student in Sun’s group, wanted to see if shrinking the gold down to nanoparticles might make it more selective for CO2. They found that the nanoparticles were indeed more selective, but that the exact size of those particles was important. Eight nanometer particles had the best selectivity, achieving a 90-percent rate of conversion from CO2 to CO. Other sizes the team tested — four, six, and 10 nanometers — didn’t perform nearly as well.

“At first, that result was confusing,” said Andrew Peterson, professor of engineering and also a senior author on the paper. “As we made the particles smaller we got more activity, but when we went smaller than eight nanometers, we got less activity.”

To understand what was happening, Peterson and postdoctoral researcher Ronald Michalsky used a modeling method called density functional theory. They were able to show that the shapes of the particles at different sizes influenced their catalytic properties.

“When you take a sphere and you reduce it to smaller and smaller sizes, you tend to get many more irregular features — flat surfaces, edges and corners,” Peterson said. “What we were able to figure out is that the most active sites for converting CO2 to CO are the edge sites, while the corner sites predominantly give the by-product, which is hydrogen. So as you shrink these particles down, you’ll hit a point where you start to optimize the activity because you have a high number of these edge sites but still a low number of these corner sites. But if you go too small, the edges start to shrink and you’re left with just corners.”

Now that they understand exactly what part of the catalyst is active, the researchers are working to further optimize the particles. “There’s still a lot of room for improvement,” Peterson said. “We’re working on new particles that maximize these active sites.”

The researchers believe these findings could be an important new avenue for recycling CO2 on a commercial scale.

“Because we’re using nanoparticles, we’re using a lot less gold than in a bulk metal catalyst,” Sun said. “That lowers the cost for making such a catalyst and gives the potential to scale up.”



SOURCE  Brown University

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 Space  

Researchers have revealed that neutron star collisions are responsible for the formation of virtually all the heavy elements in the universe—a list that includes gold, mercury, lead, platinum and more.

Gold is valuable to us for many reasons: its beauty, its usefulness as jewelry, and its rarity. Gold is rare on Earth in part because it's also rare in the universe. Unlike elements like carbon or iron, it cannot be created within a star.

 Instead, it must be born in a more cataclysmic event - like one that occurred last month known as a short gamma-ray burst (GRB). Observations of this GRB provide evidence that it resulted from the collision of two neutron stars - the dead cores of stars that previously exploded as supernovae. Moreover, a unique glow that persisted for days at the GRB location potentially signifies the creation of substantial amounts of heavy elements - including gold.

"We estimate that the amount of gold produced and ejected during the merger of the two neutron stars may be as large as 10 moon masses - quite a lot of bling!" says lead author Edo Berger of the Harvard-Smithsonian Center for Astrophysics (CfA).

The team's results have been submitted for publication in The Astrophysical Journal Letters and are available online.

Berger presented the findings in a press conference at the CfA in Cambridge, Mass.

A gamma-ray burst is a flash of high-energy light (gamma rays) from an extremely energetic explosion. Most are found in the distant universe. Berger and his colleagues studied GRB 130603B which, at a distance of 3.9 billion light-years from Earth, is one of the nearest bursts seen to date.

Gamma-ray bursts come in two varieties - long and short - depending on how long the flash of gamma rays lasts. GRB 130603B, detected by NASA's Swift satellite on June 3rd, lasted for less than two-tenths of a second.

Image Source: Dana Berry, SkyWorks Digital, Inc.

Although the gamma rays disappeared quickly, GRB 130603B also displayed a slowly fading glow dominated by infrared light. Its brightness and behavior didn't match a typical "afterglow," which is created when a high-speed jet of particles slams into the surrounding environment.

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Instead, the glow behaved like it came from exotic radioactive elements. The neutron-rich material ejected by colliding neutron stars can generate such elements, which then undergo radioactive decay, emitting a glow that's dominated by infrared light - exactly what the team observed.

"We've been looking for a 'smoking gun' to link a short gamma-ray burst with a neutron star collision. The radioactive glow from GRB 130603B may be that smoking gun," explains Wen-fai Fong, a graduate student at the CfA and a co-author of the paper.

The team calculates that about one-hundredth of a solar mass of material was ejected by the gamma-ray burst, some of which was gold. By combining the estimated gold produced by a single short GRB with the number of such explosions that have occurred over the age of the universe, all the gold in the cosmos might have come from gamma-ray bursts.

"To paraphrase Carl Sagan, we are all star stuff, and our jewelry is colliding-star stuff," says Berger.



SOURCE  Harvard-Smithsonian Center for Astrophysics

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