Orbite Aluminae Message Board - Msg: 27808492

SiliconInvestor

register

Sponsor

register

Gold/Mining/Energy : Orbite Aluminae

Public Reply | Prvt Reply | Mark as Last Read | File

Previous 10 | Next 10 | Previous | Next

To: Whaspe who wrote (318)	12/6/2011 6:11:08 PM
From: E. Charters	Read Replies (1) of 5040

Acidulation must proceed by the stoichiometry of the solvent and solute ions. To achieve complete dissolution of aluminum you need to use as more acid mole per mole than there are moles of Al. The acid you start with is 34% HCL, so you need about 3 times the weight of the standard industrial liquid HCL solvent (10 molar) to be equivalent to one weight measure of Aluminum by molarity. As I pointed out, you are ending up with AlCl3, which would require a lot of HCL. But you need to start with about 1.176 HCL for 1 Al. If I were dissolving any metal from an ore powder I would normally use twice weight of liquid solvent to the weight of the ore. Assuming the host material for the Al is not soluble or sparingly soluble in chloride solution, I would tend to that formula. 2Al+6HCl = 2AlCl3+3H2 plus an increase for complete exposure of alumina to acid molecules. Under elevated temperature and pressure I don't know what that excess would be but it is found that at elevated temperatures one can use 10 times the volume of 3 molar acid to clay to dissolve perhaps +60% of the naturally occurring Alumina in clay. The industrial acid strength is about 10 molar, which means it will dilute down to to 3.33 volumes of 3 molar acid, which is optimal for clay or calcined clay dissolution. For one tonne of ore, one would need ~10 tonnes of diluted - or 3 molar acid solvent - for one tonne of clay that runs 25% Al2O3. Rough stoichiometry of the mix might be One tonne clay = 250 Kg Al2O3 -- This is 132.31 kgs Aluminum 10 tonnes 3 molar acid contains 1093 kgs of pure HCL This appears to be twice by formula what acid you need to dissolve the Al. i.e. 2Al combines with 6 HCL which is a ratio of 53.96 Al to 218.7 HCL = 1:4.05 In other words by formula you need +4 times the weight of pure HCl in ratio to weight of Aluminum to dissolve the metal in clays. But empirically you need twice that. The increase in temperature and pressure such as you would find in an autoclave will increase the rate of reaction and probably the degree of extraction, but should not fiddle with the stoichiometry unless you are talking gaseous states. Less acid is needed in a gaseous state to dissolve Al. You can go right to 1 to one acid to metal but that compound is unstable. Usually one oxidizes the clay or calcines it before acidulation as it improves extraction and reduces other problems with the reaction. There are advantages with regard to iron and fines to the acidic process over the alkaline one. Alkalis were more efficient and cheaper in the past. EC<:-}

Report TOU Violation

Share This Post

Public Reply | Prvt Reply | Mark as Last Read | File

Previous 10 | Next 10 | Previous | Next

Copyright/IP Policy

Copyright © 1995-2013 Knight Sac Media. All rights reserved.