Abstract: A process for the treatment of spent pot linings impregnated with alkali metal cyanide and fluoric products by grinding previously crushed pot linings in the presence of lime, suspending the ground pot linings in an aqueous medium in order to precipitate a flux in the form of CaF.sub.2 accompanied by the release of soda, followed by the heating of the suspension at a temperature T>140.degree. C. in the presence of clay to form, after fixing the free soda, insoluble synthetic silicate compounds of the feldspathoid or zeolite type and finally the separation by filtration of the resulting solid phase from the liquid phase, which liquid phase is recycled to form a new ground pot lining suspension.

Abstract: Process for pretreatment at atmospheric pressure or a pressure close to atmospheric pressure by alkaline wetting and holding at temperature of natural materials whose gangue comprises argillaceous compounds capable of forming a stable plastic suspension in the presence of water and containing at least one combustible element which can be put into useful form wherein, in order to permit subsequent easy operations for separation of the liquid aqueous and solid phases of the gangue:(a) the natural material which was possibly been subjected to a preliminary drying operation is brought into intimate contact with at least 4 kg expressed in terms of OH.sup.- of at least one alkaline agent per ton of clay contained in said material, the total volume of liquid present in the natural material after the contacting operation being such that the ratio L/S of said volume expressed in terms of cubic meters to the weight of solid expressed in tons of dry ore is at most equal to 0.

Abstract: A process for pretreatment at high temperature by means of an aqueous pretreatment solution, of crushed ores containing at least one usable metal element, whose gangue contains argillaceous compounds which, in the attack operation for making use of the ore, are capable of forming a stable plastic suspension in the presence of water, which makes it virtually impossible subsequently to separate the liquid and solid phases by virtue of its character being such that it cannot be subjected to filtration and/or settlement, which is characterized in that, to cause stabilization of the argillaceous gangue before the operation of subjecting the ore to attack and to produce easy separation of the liquid and solid phases after the attack operation, the ore, the granulometry of which is at most equal to the liberation sieve mesh size of the metal or metals to be put to use, and before being subjected to the attack operation for making use of the ore, is brought into contact with an aqueous pretreatment solution containin