b'Seismic window ago I was using teleseismic1 arrivalsEast African Rift. Back then the coldearthquakes as they have a point source to model the structure beneath thewar was going strong, and the Sovietsand known onset time with little noise. were testing nuclear weapons inAn example seismogram of a nuclear 1Teleseismic arrivals are seismic waves that doKazakhstan. The resulting explosionsexplosion is shown in Figure 1. Example not travel through the Earths core but travelprovided useful data for my project.seismograms from earthquakes are through the mantle and crust. Explosions are much cleaner thanshown in Figure 2.Figure 2.Example seismograms of earthquakes recorded in East Africa. These recordings are noisy Figure 1.Example seismogram of a nuclear test in Kazakhstan recorded in East Africa. The verticaland variable when compared to the seismogram component has minimal noise with a clear first break. Compare this to the seismograms in Figure 2. in Figure 1.Henderson Byte: Biomining and bioleachingBiomining and bioleaching are techniques for extracting metals from ores and other solid materials typically using single-celled organisms like bacteria, and by fungi or plants (the latter is also termed phytomining). These microorganisms gain energy by breaking down minerals into their constituent elements.As we strive for a carbon-free low-emissions future, the metals necessary to construct wind farms, solar cells and electric batteries will become more in demand. Mine tailings are a repository for such metals, but currently the concentrations are less than commercially viable. With an increasing requirement for these metals, the techniques of biomining and bioleaching (for tailings) will become more viable.It was discovered in the mid-1900s that some microorganisms use metals in their cells. Some of these microbes can use stable metals such as iron, copper, zinc and gold, as well as unstable atoms such as uranium and thorium. Biomining via microorganisms is capable of extracting metals from low grade ores, such as tailings, an important consideration with the inevitable future depletion of high-grade deposits. Biomining is also an environmentally friendly technique releasing only gases that the bacteria secrete.Bioleaching can partially replace the extensive crushing and grinding that translates to high cost and energy consumption in a conventional process. Bioleaching is much cleaner than the traditional heap leaching using cyanide.Bacteria such as Acidithiobacillus ferrooxidans can leach copper from mine tailings with improved recovery rates and reduced operating costs. It was also found that these bacteria grow faster and are more motile in high iron concentrations. Whereas gold is frequently found in nature associated with minerals containing arsenic and pyrite, Acidithiobacillus ferrooxidans and its relatives are able to attack and make soluble the arsenopyrite minerals and, in the process, release the gold.Large cultures of microbes, or chemostats, can be grown to leach metals from their media. These chemostats can then be transformed into many marketable metal compounds. The development of such industrial mineral processing has been established now in several countries including South Africa, Brazil and Australia. As continual biomining research leads to new technologies their implementation may lead to higher metal yields.A recent paper, entitled, Plants to mine metals and remediate land, (see reference) is recommended along with its references for further information on this topic especially for phytomining.ReferenceRylott, E. L. and Bruce, N. C., 2022. Plants to mine metals and remediate land, Science, 377 (6613), 23 September 2022, 1380-81.Roger Henderson rogah@tpg.com.au41 PREVIEW APRIL 2023'