Gold, precious forever but especially lately, is a tricky metal. Bound up in consumer electronics, jewelry and the ores that it comes from, gold is difficult to extract, and most modern processes do it with a highly toxic combination of cyanide salts. The cyanide leaches the gold out, but the cyanide can seep into the ground, causing environmental problems and posing threats to human health.
Researchers at Northwestern University recently stumbled upon a solution that uses cornstarch instead. It involves some complex chemistry, but its cheap, biologically friendly and nasty-ingredient-free.
Led by Sir Fraser Stoddart, a chemistry professor at Northwestern, the team discovered this method by accident when looking for something else. A postdoc named Zhichang Liu was trying to make three-dimensional cubes out of gold and starch, aiming to use them as storage containers for gases and small molecules. But a liquid mixture of dissolved gold-bromide salts and a starch-derived sugar didnt form cubes, it formed needles. This was strange, so the team decided to try to replicate it and tested different forms of sugars.
Alpha-cyclodextrin, a cyclic starch fragment with six glucose molecules, is the best way to isolate gold, they found. Zhichang stumbled on a piece of magic for isolating gold from anything in a green way, Stoddart says in a statement. The spontaneous bundle of needles is made of thousands of nanowires, each 1.3 nanometers in diameter, which contain a charged gold atom inside four bromine atoms.
The interaction between the starch fragment and the gold allows the precious metal to be selectively recovered from other materials, including platinum, palladium and others. The researchers already developed a process to isolate gold from scraps, and they hope this will lead to an environmentally friendly, cheap way to recover gold from anything. The research is published in Nature Communications.
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For its extensive practical experience, 911 Metallurgisthas a clear understanding of what successful mineral processing engineering is and how to go about achieving it. Your goal is the production of a material that is marketable and returns you and your investors sustainable revenues.
Although improvements to the metallurgical processes have been made over the years the fact is that the unit operations, the machines, those too often called black boxes involved have not evolved or changed much since inception. Ore is reduced in size, chemicals are added and minerals separated and upgraded to produce a marketable product. Much of this process is mechanical and generally mistaken for some dark alchemy.We are the Anti-Alchemists.
Our vast experience has been gained through operation and start-up of both small and large scale mining/metallurgical operations in a range of commodities in thebase metals (Cu, Pb, Zn) and theprecious metals (Au, Ag,)
A solid metallurgist understands, the most important aspect of an operating process is its stability. Simple to say, but generally the most ignored in mineral processing. Linked unit operations require each to be stable, and each contains a different set of variables that have to be contended with. Thanks to some degree of stability: operating changes can be made and evaluated; increases in throughput can be made; and equipment performance improved. The more complicated the processes become, the more difficult it is to achieve and maintain stability. In mineral processing, unlike most processing operations, we have limited control of the main input, the feed ore. In most cases this inherently is variable and usually outside of the processors control.
Because you are too close to your own story, you might not see the forest for the trees and have chaos mistaken for stability. We, you, and your group have been battling plant problems for weeks, you start to accept chaos as a daily state of affair and consider it your new stability.
Each mineral processing plant is different: with varied ore types, mining equipment, and management (operating) philosophy. The evaluation and prioritisation of variables that affect the plant performance is the primary function. Implementing changes within the constraints imposed can be difficult, as resources may be limited.
Invariably the ability to solve problems can be confusing due the large numbers of variables that may impact the processes. In most cases problems are not metallurgical in nature but rather operational and mechanical. Problem solving is a process and in many operations this ability is absent. All too often many changes are made together without a solution resulting, on more confusion. Most plants learn to live or survive their problems, not to solve them.
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