Smelting

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staff on 2009/12/29 13:46
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An article “An economical “Solar-pumped laser” produces ultra high temperature” shows that solar-pumped-laser realized ultrahigh-temperature which is impossible with simple concentration of sunlight.
The following movie is an experiment of solar-pumped-laser at Tokyo
Institute of Technology in January 2009. Output of laser was 50W. It can drill a hole on a 0.1mm-thick stainless plate easily.

The next movie shows deoxidation of magnesium oxide with
solar-pumped-laser. You will see the smoke from MgO at the instance
when the laser is correctly focused. The output is not enough for commercial smelting, but deoxidation itself is possible.

staff on 2009/12/22 11:30
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An article “Can a laser smelt magnesium?” explains that laser can evaporate the surface layer of the powder of magnesium oxide, and extract metal magnesium.
The following movie shows the moment that magnesium oxide vaporizes with laser for 0.5sec (1/60 high-speed videography). When magnesium oxide vaporizes in an instant, evaporated materials rise vertically. Therefore we can extract specified elements easily.
30% of collected materials are magnesium oxide, and 70% are metal magnesium. It means we can get 70% pure magnesium with laser smelting. 70% is enough for fuel. By comparison, purity of magnesium with Pidgeon method is 80% at the first stage, and then refinement process makes it purer.

staff on 2009/12/21 22:10
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Question:
How much is conversion efficiency of magnesium with solar-pumped-laser smelting?

Answer:

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staff on 2009/12/15 11:55
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Even if the recycling technologies for magnesium is established, where do we obtain magnesium itself? If we are to procure the quantity of magnesium to circulate as energy currency in the current method of mining dolomite, the mining itself would require a huge amount of energy and cost.
Our plan is to obtain magnesium from the sea. There is 1,800 trillion tons of magnesium in the sea in the form of magnesium ion. As everyone knows, you can obtain magnesium chloride (nigari) by condensing the sea water. It follows that we can condense the sea water to obtain magnesium compound, and then we illuminate this with a solar-energy-pumped laser to produce pure magnesium.
Magnesium chloride in the sea water is called hydrous magnesium chloride, which contains chemically bonded water. When it is heated, the water is removed to yield magnesium oxide. The process that follows is essentially the same as the recycling process for magnesium oxide. Acidum hydrochloricum is produced along with magnesium oxide, but it is relatively easy to handle this because it is liquid.

staff on 2009/12/14 23:08
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Carbon dioxide gas laser smelts magnesium

Carbon dioxide gas laser smelts magnesium

We have verified that we could obtain 400W-1kW level of power from a solar-energy-pumped laser. Following this result, we went on to conduct another experiment, using a different type of commercial laser, in order to see if we could in fact obtain magnesium. We illuminated magnesium oxide powder with a 1kW carbon dioxide gas laser for 0.2 seconds. This evaporated the surface layer of the powder to produce gas, and we verified that 30% of the gas was magnesium atoms. What is important here is how efficiently we can obtain pure magnesium. The energy reduction efficiency is defined as the ratio of the amount of energy produced by burning magnesium to the amount of laser energy required to produce the magnesium. The larger this efficiency, the better. The efficiency we obtained from the experiment was 45%, which is very close to our target of 50%.

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staff on 2009/12/14 09:33
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The amount of magnesium produced world wide in one year is about 600,000 tons. About 70% of this is produced in China, and it is refined using a thermal reduction method. Coal is used as the heat source. It is said that about ten tons of coal is needed to produce one ton of magnesium. This is a very energy consuming process.
It is popularly assumed that we need catalyst such as ferrosilicon in order to refine magnesium. The catalyst is required in order to cut the chemical bond between oxygen and magnesium in magnesium oxide at a relatively low temperature of a thousand and several hundred degrees Celcius. If you factor in energies needed for latent heat to evaporate magnesium and for cutting chemical bond between atoms, the reaction would not occur unless we heat the magnesium oxide up to 20,000 °C. But this also means that as long as the magnesium oxide is given an energy corresponding to 20,000 °C, the bond between its oxygen and magnesium would be broken naturally.