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The aluminum oxide layer formed by anodizing will have substantially higher corrosion and abrasion resistance than non-anodized aluminum. For most applications, simple Type II sulfuric acid anodizing is sufficient. For maximum protection, Type III hard anodizing will yield a much thicker coating with substantially higher corrosion and abrasion resistance. ...


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We can explain this with the example of $\ce{CO + O2 <=> CO2}$. Here we have to focus that there are two reactants on one side and there is only one reactant on the other. The sum of the entropy of the reactants is subtracted from the entropy of the products, which would result in a negative entropy change in the present example of ideal gases, and ...


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The black slag is copper oxide and silver oxide (both are black compounds). If you're trying to refine the sterling silver, i.e. remove the copper and other base metals, then you're approaching this incorrectly. You could theoretically remove the base metals via pyro, but you'll lose a ton of silver to the slag. I'd recommend a hydrometallurgical approach ...


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Voffch mentioned that borax is a flux. Quite true; borax beads are used for determination of various metals, and copper or silver would give characteristic colors, like green and whatever silver gives. Fluxes are also solvents for metal oxides, like the refractory material of the crucible. While molten alloys should be containable by refractory crucibles (I'...


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Gold looks pretty soluble in molten zinc. The melting temperature increases up to about 625 C with 50% gold.Charcoal on the surface of the melt will partly protect the zinc ; I have seen charcoal used on lead but not zinc.


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It depends on the concentration of Pt in your alloy. If the concentration of Pt is to high the HCl will not or not sufficently attack the alloy. In this case you could try to melt your alloy with some additional Fe, to lower the Pt concentration and then hit it with HCl again. You could also try to boil it in HCl to increase the reactivity of the acid (do ...


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Indeed if you do the cupelation, the lead will form litharge and some parts of the litharge will volatilize. But usually the cupel is made out of bone matter - this is very porous. While the molten lead and the gold will stay in the cupel, the litharge will be absorbed by the cupel like a sponge. If all lead is converted to litharge and all litharge is ...


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When I was working with silver a back powder was often formed. I have found out, that this black powder was silver oxide. Don't know if it is silver oxide in your case, but it likely is.


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Reason 1: For example if you have an porous ore and you melt it, the surface area will decrease dramatically. If you just roast it, the surface area will stay about the same. A higher surface area will aid calcination proceses as more oxygen gets into contact with the surface and will eventually react. Reason 2: A higher temperature means more energy to ...


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Let me give an extreme example of chemical analysis. It is an anecdote. Some analytical chemists were using a very sensitive technique to analyze metals in blood. It is called neutron activation analysis. What they saw was that a very small quantity of molybdenum (Mo) was present in small quantities persistently. Nobody expected that. It turned out after a ...


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Some tools were made of "pure" copper. But tin was the best and only available addition to copper for strength. At the time tin was the only type of bronze. Today a variety of copper alloys are called "bronze" that do not contain tin. Lead could possible have been available depending on time and place but it does not improve strength of copper and could ...


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I think the difference is due to the way eddy currents form Magnetohydrodynamics. As the current flows through the conductive liquid, a magnetic field is produced. This in turn causes the liquid to be pushed (at right angles to the current and field). In one version of the cell, this current causes stirring of the aluminum, alumina, flux mix. This is more ...


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