Specialized metallurgical processes – compositions for use therei – Processes – Electrothermic processes
Patent
1984-11-28
1986-09-23
Doll, John
Specialized metallurgical processes, compositions for use therei
Processes
Electrothermic processes
75101R, 75108, 423 2, 423 3, 423 22, 423 27, 423 53, 423 66, 423 98, 423104, 423127, 423140, 423150, C22B 100
Patent
active
046133615
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a process for pretreatment at high temperature, by means of an alkaline aqueous solution, of ores containing at least one usable element, the gangue of which contains argillaceous compounds which are capable of forming a stable plastic suspension in the presence of water.
The applicants use the term `pretreatment` to define a hydrometallurgical treatment prior to extraction of the usable element or elements in the ore in order subsequently to impart to the solid phase, in the presence of a liquid phase, a capacity for easy separation of the two phases in question.
The applicants use the term `usable element` to define all the metallic elements which are present in at least one of the minerals constituting the argillaceous ore, which are capable of being extracted therefrom in order to be put to use, such as for example uranium, vanadium, molbdenum, gold, nickel . . . .
The man skilled in the art has long been aware that argillaceous compounds forming the gangue of certain ores (which it would be desirable to make use of) have a real tendency to swell, then split up and finally disperse in the form of fine crystals and small agglomerates in contact with an aqueous phase. That phenomenon makes it very difficult to carry out hydrometallurgical treatments for making use of such ores since the suspension produced becomes unsuitable for separation of the liquid and solid phases, both by filtration and by settling, or the suspension may occur in a condition of high viscosity.
Argillaceous compounds which are capable of forming a stable plastic suspension upon contact with water, which are frequently present in the above-mentioned argillaceous-gangue ores, may belong to the groups formed by kaolinites such as for example kaolinite, dickite, halloysite, disordered kaolinites and serpentines; the mica group such as for example muscovite, biotite and paragonite, pyrophyllite and talcum, illites and glauconite; the montmorillonite group such as for example beidellite, stevensite, saponite and hectorite; the chlorite group; the vermiculite group; the group of interstratified clays whose unitary structure is a combination of the preceding groups; the group of fibrous clays such as for example attapulgite (palygorskite) and sepiolite. Such argillaceous-gangue ores may also contain other compounds such as for example quartz, calcite (CaCO.sub.3), dolomite, gypsum, limonite (FeO(OH)nH.sub.2 O) and other metal oxides and hydroxides.
If hydrometallurgical processes for the treatment of ores, that is to say, for attacking ores, are generally well known to the man skilled in the art, it is also well known that argillaceous-gangue ores require specific treatments which are adapted to the gangue and/or to the element included therein, which is to be put to use.
It is found that it is, if not impossible, at least very difficult simply to transpose known hydrometallurgical processes for treating ores having a gangue which is at most slightly argillaceous, to ores having a gangue which is highly argillaceous, because the suspension resulting from the attack operation is found to be unsuitable for separation of the liquid and solid phases.
Among hydrometallurgical processes for treating ores, for example uraniferous ores, it is known preferably to effect the alkaline oxidising attack on the uranium ore by means of an aqueous solution of sodium carbonate and/or bicarbonate. The attack operation is generally performed in the presence of free oxygen which is blown into the hot reaction medium in order to permit oxidation and solubilisation of the uranium but also to provide for oxidation of the sulphides of impurities and the organic materials present in the ore.
Thus, the specialist literature in this art has described modes of operation for carrying out the oxidising alkaline attack operation (The extractive Metallurgy of Uranium, by Robert C. Merritt, edited by Colorado School of Mines Research Institute 1971 edition, pages 83 ff).
A first mode of operation comprises attacking a uraniferous ore, prefer
REFERENCES:
patent: 2992887 (1961-07-01), Thunaes
patent: 3238038 (1966-03-01), Hunter et al.
Lamerant Jean-Michel
Pallez Francois
Personnet Pierre-Bernard
Doll John
Stoll Robert L.
Uranium Pechiney
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