Because it requires toxic chemicals and produces greenhouse gases, ore smelting can be a messy industrial process. Fortunately, MIT researchers have found a new way of separating metal from impurities that could be potentially cheaper, safer and less harmful to the environment than traditional ore processing methods.
Originally, the researchers were testing a new chemical formulation for the development of a new kind of high temperature storage battery. The formulation used antimony sulfide, in addition to a second electrolyte (a blend of sodium chloride, potassium chloride, and sodium sulfide), between the positive and negative electrodes of the battery. But when the battery wouldn’t hold a charge, they opened it up to find that the antimony sulfide had completely separated into pure liquid antimony and gaseous sulfur.
By trying to figure out the cause of this reaction, they discovered that the second electrolyte was a good ionic conductor, which caused the antimony sulfide to undergo electrolysis – separating the metal from the sulfide compound. Electrolysis is the same reaction a jeweler uses to apply rhodium plating.
In typical smelting processes, the sulfur would immediately bond with oxygen in the air to form sulfur dioxide, a common source of air pollution. Since the electrolysis developed by MIT is contained in the "battery," it provides purified metal without the need to worry about scrubbing/filtering out pollutants. Although researchers have only demonstrated the process with antimony, they believe that the same principles may also be applied to producing much more economically important metals such as copper and nickel.
Gold prices continue to make newsworthy changes as 2016 comes to a close. Just before Thanksgiving, gold prices fell to less than $1,200, marking a nine-month low for the metal.
Despite the timing, this discount on gold had nothing to do with Black Friday. At least, not in the way you might think. Investor speculation has been pointing toward a stronger currency market brought on by increased spending – not just by consumers, but also through the US government and the expectations being set by President-elect, Donald Trump.
But an even bigger influence on gold prices came from speculation that the US Federal Reserve will finally raise interest rates. From an investment standpoint, gold provides no yield, so any gains for investors come through price appreciation. If the Fed raises interest rates, then the opportunity costs of holding gold also increases, making it a less desirable investment.
The Fed won’t make an official announcement on interest rates until its December 13-14 meeting. Gold prices could move in either direction depending on the outcome of that meeting. You can stay in the loop by downloading our precious metal prices app and setting up alerts.
Scientists from Rice University have created a new type of alloy, using a 3-to-1 mixture of titanium and gold, which could vastly improve the quality and durability of medical implants and prosthetics.
Because it is biocompatible (non-toxic) and resistant to wear, titanium is the standard material for medical prosthetics like artificial joints. Unfortunately, they eventually do wear down and require replacement every 10 years or so. In testing their new alloy, called beta-Ti3Au, Rice University researchers found it to be four times harder than pure titanium - suggesting it could be used to create prosthetics that last much longer. Since the alloy is extraordinarily strong, it could also have applications in mining, drilling, and safety equipment.
Since it is also biocompatible, it’s easy to imagine gold being used in new types of medical implants. However, gold is also the most malleable metal – which begs the question: how does gold combine with titanium to form such a strong alloy? The answer lies in the way the atoms of the alloy are arranged.
The researcher’s key discovery was not the idea to combine gold and titanium – it was the change that occurs when the metals are combined at higher temperatures. Combining the metals at a low temperature creates alpha-Ti3Au, a known alloy which has properties comparable to regular titanium. High temperatures cause the atoms to arrange into a more crystalline structure, creating the beta alloy. According to the research abstract, the alloy’s structure allows for “elevated valence electron density, reduced bond length, and pseudogap formation" - all of which increase its hardness.
Image attribution: Svanidze, Eteri, et al. "Fig. 2 Structural analysis of the Ti0.75Au0.25 alloy." Figure. Science Advances, 20 July 2016, advances.sciencemag.org/content/2/7/e1600319.figures-only. Accessed 2016.