Potential Methods of Ore Extraction on the Lunar Surface
By Alexander M. Lapides
Abstract:
1. Introduction
Since the beginning of time, the moon has been a thing of wonderment to humans, a symbol of the unknown and larger universe. Now more than ever, a push has been made to commercialize the moon, with entrepreneurs and risk-takers investing billions in the newest high-tech equipment needed to reach the moon and harvest its natural resources. The Artemis Society, an international association, has been formulating its Artemis Project for several years, with the hope that one day, science and commercialization will be the primary goals of the first privately-supported lunar land-base and tourist destination. Although one goal of the project will be the development of a commercialized environment on the moon, science offers equally attractive objectives. For instance, the proposed production of solar cells on the moon would provide a solution to the energy crisis on earth for years to come. However, solar cells, rockets, and commercial environments all need raw chemicals in order to function. Therefore, it is necessary to examine the various methods of ore extraction which can take place on the moon. This report will focus on specific types of extractive processes, including electrometallurgy, chemical reactions, and novel concepts proposed by scientists. Then, based on the findings, a brief solution will be suggested.
2. Electrometallurgy
2.1: Definition
One of the potential extraction techniques is electrometallurgy. Although the term electrometallurgy implies that only metals will be extracted from lunar soil, this is not the case. One of the main chemicals being targeted for ore extraction and processing is liquid and gaseous oxygen, because of its use in rocket fuels and simple respiration. Electrometallurgy, which is defined as using electricity and electrolysis in order to separate a compound into its component elements or molecules or to reduce a metallic compound into simply the metal itself, has great potential on the moon because of its lack simplicity, dual extraction-purification purposes, and tested reliability.
2.2: Specific Uses in Artemis
2.2.1: Magma Electrolysis
In the process of magma electrolysis, lunar soil (also known as regolith) is collected, heated to super-hot temperatures using concentrated sunlight, which can reach 5500 degrees Celsius, and is, essentially, melted. Then, the liquid rock is subjected to simple electrolysis, which separates the oxygen (which is the most abundant element in the lunar crust) from the metallic elements with which it commonly bonds, including magnesium, aluminum, calcium, iron, and silicates. One the problems of this process is that one of the electrodes in the electrolysis process would need to be made (or at least coated) with platinum, because of the elementŐs inertness in reactions (the other electrode could be made from steel). Also, platinum is corroded without much difficulty in the presence of silicates, one of the products of the electrolysis. Therefore, this type of extraction might prove costly if the electrodes need to be continually replaced. However, this process has many positive aspects too. A small amount of equipment is involved and the process itself is very simple. Also, the quantity of elements yielded could make this a promising universal (no pun intended) extraction technique.1
2.2.2: Silicate Minerals
One of the main goals of the Artemis Project is to mine enough silicon on the moon (Silicon comprises 21% of the lunar soil.) to be able to produce enough solar panels to, more or less, solve the energy crisis on Earth. Therefore, it is necessary to mine silicon in a reliable and cost-effective way. One proposed method is to use electrolysis on silicate minerals (such as CaAl2-Si4O8) to extract the silicon, oxygen, and, theoretically, the other elements involved as well. Though few experiments have been run, this method requires little energy, no refinement, no reactants, little equipment, and is not complex in nature. A variation on this is called flux silicate mineral processing. In essence, itŐs the same thing, except one must first reduce the CaAl2-Si4O8 with aluminum. This immediately yields solid silicon for the production of solar cells. The other end products are calcium oxide (CaO) and aluminum oxide (Al2O3). Besides the immediate production of solid silicon, the flux process also requires less energy than the normal method, has less corrosion involved, and has higher conductivity in the electrodes. The downside to this method (as with the magma electrolysis) is that the life of the electrodes is unknown and could come at a cost that might jeopardize this method of extraction. The main obstacle still to overcome is finding a cheap, yet reliable electrode for the electrolysis process.