Abstract: The invention is a process and an apparatus for removing metal contamination from soil. In the method, the soil is treated to produce soil with a small particle size. The particulate soil is then separated into a coarse fraction and a fine fraction. The coarse fraction and the fine fraction are contacted with a leach solution in separate contacting zones to remove the metal contamination from the soil, the metal is removed from the leach solution and the leach solution recycled to the leaching zones.

Abstract: A process is described for solubilizing lead contained in ores mineralized with sulphidic minerals by in-situ leaching with an acetic acid and acetate containing solution in presence of an oxidant. The in-situ leaching is conducted by means of drillholes in the ore body. In another embodiment the acetic acid and acetate containing solution is percolated through a bed of crushed untreated rock or unconsolidated mineral particles, mill tailings and/or agglomerated or unagglomerated sulphidic lead containing waste material, forming a pile or a layer in an open vat, in presence of an oxidant. Lead is recovered from the pregnant lead acetate containing solution and the solution may subsequently be recycled to further leaching of lead sulphidic minerals or lead sulphide containing particles.

Abstract: Fly ash from incineration plants is treated with an acidic aqueous solution for the purpose of removing heavy metals. The residual solid matter is filtered. The filtration residue is treated with a precipitating agent for heavy metals. The thereby obtained inert residue can be directly dumped.

Abstract: Heavy metals are efficiently removed from contaminated soil by a process which comprises leaching or washing the soil with a mild leachant solution comprised of an aqueous solution of an acid and a salt. Heavy metals are also efficiently removed from paint chips by washing with an aqueous acid. The heavy metals are recovered from the leachant be cementation.

Abstract: Heavy metals are removed from paint chips by leaching with an aqueous acid. Heavy metals are also efficiently removed from contaminated soil by a process which comprises leaching or washing the soil with a mild leachant solution comprised of an aqueous solution of an acid and a salt. The heavy metals are recovered from the leachant by cementation.

Abstract: The invention is a process and an apparatus for removing metal contamination from soil. In the method, the soil is treated to produce soil with a small particle size. The particulate soil is then separated into a coarse fraction and a fine fraction. The coarse fraction and the fine fraction are contacted with a leach solution in separate contacting zones to remove the metal contamination from the soil, the metal is removed from the leach solution and the leach solution recycled to the leaching zones.

Abstract: To remove lead, cadmium and zinc from dusts produced in the electrostatic precipitator in the electrothermal production of yellow phosphorus, the dusts are first digested by phosphoric acid having a content of at least 25% by weight of P.sub.2 O.sub.5 at temperatures above 60.degree. C. in a ventilated reaction zone. The digest solution is then separated in a filter zone into an essentially lead-, cadmium- and zinc-free solid residue and a phosphoric acid containing dissolved lead, cadmium and zinc.

Abstract: The present invention relates to the decontamination of soil and the like and, in particular, soils which are contaminated with metal as a result of the activities of human beings. The invention provides a physical and a chemical means for treating soil aggregate so as to obtain a product aggregate having a relatively low metal content. The physical means is characterized by the classification of a soil aggregate into portions of differing size and metal content. The chemical means is characterized by contacting a soil aggregate with an aqueous lixiviant comprising an organic acid component to lift metal from the aggregate. The physical and chemical means may be used in a combined process for decontaminating soil aggregate.

Abstract: A method for the continuous treatment of air pollution control residues from various resource recovery systems whereby the air pollution control residue is treated with a dilute salt extracting solution at a pH chosen to maximize the recovery of lead, for a reaction time chosen to maximize the recovery of lead, and for a number of recycles chosen to maximize the recovery of lead from the particular residue being treated. Other metals and dissolved salts can also be recovered from the extracting solution. Thus by monitoring these three variables for each batch of residue, and adjusting the extracting solution accordingly, residue from various sources and of varying composition can be treated efficiently and continuously to remove hazardous metals and dissolved salts from the residue. Bottom residue fines, alone or admixed with air pollution control residues, can also be treated in accordance with the process of the invention.

Abstract: A process is described for recovering metal values, e.g., gallium, contained in an aqueous solution by extraction comprising the steps of contacting the aqueous solution with a water immiscible organic phase comprising a water-insoluble substituted 8-hydroxyquinoline whereby the metal values are transferred into the organic phase; separating the organic phase from the aqueous solution and recovering the metal values from the organic phase. The novel feature comprises recovering the metal values by contacting the organic phase containing metal values with an aqueous solution of a strong base whereby metal values are removed from the organic phase to the aqueous solution with the aqueous solution containing the recovered metal values having a concentration of at least 4.6 moles per liter total hydroxide, and then separating the metal values from the aqueous phase.

Abstract: A germanium bearing sulphate solution containing indium and/or gallium is brought at pH 1-2.5 into contact with an organic phase, containing a substituted 8-hydroxyquinoline and an acid organophosphorus compound. So, in addition to germanium, indium and gallium are also extracted from the sulphate solution.

Abstract: A quaternary ammonium trihalide, a novel compound, represented by the formula:[A--R'].sup.+ .multidot.X.sub.3.sup.-(wherein A stands for a trialkyl-amino radical or a pyridyl radical, R' for an alkyl radical of 6 to 22 carbon atoms, and X for a halogen atom) and a method for the dissolution of a metal with a liquid consisting essentially of an organic solvent and the quaternary ammonium trihalide.

Abstract: A process is disclosed for the two-phase extraction of metal ions from phases containing solid metal oxides, which is characterized in that the solid metal oxides are brought into contact with a hydroxamic acid, known per se, dissolved in a hydrophobic organic solvent, the phases containing the solid metal oxides and the organic phase are intensively intermixed over a sufficient contact time, after phase-splitting, the organic phase is separated and the metal ions are re-extracted from the organic phase in a manner known per se and processed.The extracting agent used therein and the use of this extracting agent are also disclosed.

Abstract: A method of releasing metals from catalysts in a form that is readily recoverable using denitrifying bacteria is disclosed. The method can be used to regenerate catalysts and to recover metals from catalysts, especially molybdenum and nickel.

Abstract: The present invention is directed to improved methods for processing battery wastes, battery casing debris and other lead contaminated materials. The improved processes of the present invention provide less environmentally stressful methods for recovering lead from such materials while at the same time producing scrap or recyclable ebonite and plastics having reduced and environmentally acceptable lead and leachable lead levels. Most of the lead is first removed by trammel scrubbing. In another aspect of the present invention ebonite and other hard surface materials to which are adhered lead contaminants are mixed with water and abraded in a high energy scrubber to remove the adhered contaminants prior to separation of the cleaned ebonite from solution. This simple and environmentally preferred hydromechanical process provides clean scrap or recyclable ebonite.

Abstract: A method and apparatus for recovering lead from scrap lead/acid batteries involves first mechanically breaking up the batteries into small pieces, then feeding the small pieces into a substantially vertical, upwardly diverging separation/leaching column through which ammoniacal ammonium sulphate solution (AAS) passes upwardly at a speed that allows the removal of metallic lead and lead alloys as sinks from the bottom of the column, with comminuted case material floating up and out of the column, while the lead compounds remain in suspension in the column for lead sulphate dissolution. The insoluble lead dirxide from the pastes is removed from the AAS downstream of the column and is slurried with sulphuric acid to convert the lead dioxide to lead sulphate, which is then returned to the separation/leaching column. The clarified AAS is fed to an electrowinning tank where metallic lead is plated out.

Abstract: A process for recovery of copper from a copper residue obtained during purification of a zinc sulfate solution comprises leaching the copper residue in a concentrated sulfuric acid solution in the presence of an oxidant at a temperature of between 60.degree. and 80.degree. C. and separating the solids from the leach solution, electrowinning copper from the leach solution, returning the electrolyte solution to the initial leaching stage to initiate dissolution of the copper residue, and bleeding a portion of the electrolyte solution to reduce the concentration of impurities in the solution.

Abstract: The present invention is directed to improved methods for processing battery wastes, batter casing debris and other lead contaminated materials. The improved processes of the present invention provide less environmentally stressful methods for recovering lead from such materials while at the same time producing scrap or recyclable ebonite and plastics having reduced and environmentally acceptable lead and leachable lead levels. Most of the lead is first removed by trommel scrubbing. In another aspect of the present invention ebonite and other hard surface materials to which are adhered lead contaminants are mixed with water and abraded in a high energy scrubber to remove the adhered contaminants prior to separation of the cleaned ebonite from solution. This simple and environmentally preferred hydromechanical process provides clean scrap or recyclable ebonite.

Abstract: A metal is dissolved by a method which comprises establishing contact of the metal with a quaternary ammonium compound and a halogenated hydrocarbon or with a quaternary ammonium compound, a halogenated hydrocarbon, and a polar solvent.

Abstract: A method and apparatus for treating mineral-bearing ores and, more particularly, for treating ores containing precious metals, base metals and the like values by providing a means to extract the metal or other values from a particulated ore by classifying the ore to separate values from the gangue, and by continuously chemically leaching the said values from the ore. In accordance with an embodiment of the invention, particulated ore is fluidized and intermittently moved through a tank to classify the ore particles into strata according to size, shape and density to beneficiate values, either heavier or lighter than the gangue, for recovery of concentrated values.

Abstract: A process for treatment of incinerator ash typically including heavy metals and both water soluble and insoluble fractions. The insoluble fraction is first removed from the fly ash. The soluble fraction is treated to precipitate heavy metal compounds. Preferably, the heavy metal precipitates are incorporated in a vitrifiable batch. In a separate vitrifiable batch, the insoluble fly ash portions may also be incorporated. Most preferably, bottom ash from the incinerator is also incorporated in a glass batch. The bottom ash glass batch may also incorporate the insoluble fraction from the fly ash.Precipitation of the heavy metal constituents in the soluble portion of the fly ash is preferably accomplished by raising the pH of the solution, most preferably above 10 by addition of alkali metal or alkaline earth metal hydroxides.

Abstract: The invention is a process for the removal of high concentrations of impurities including antimony (Sb), bismuth (Bi), arsenic (As), lead (Pb), zinc (Zn), cadmium (Cd), selenium (Se) and tellurium (Te) contained in flue dusts produced during the smelting of copper. To effect the separation, the flue dust is slurried to about 10-30 weight percent solids. Then slurry is fed to gravity separation equipment, where the lighter impurities fraction segregates from the heavier revenue metals fraction. The segregated high copper concentrate is then washed while the tailings are neutralized by lime milk, dewatered and recovered as tailings cake. The wash solution together with the thickener overflow is subjected to copper cementation to recover the dissolved copper in the solution. The lighter impurities fraction can be subjected to acid leaching in order to further recover copper therefrom.

Abstract: Disclosed is a process for leaching selected metal compounds (e.g. gallium arsenide) from integrated circuits containing those compounds. The method includes placing the integrated circuits into a culture medium containing bacteria. Bacteria capable of leaching the metal compounds from the integrated circuits leach the metals from the integrated circuits. The bacteria preferably used will be ATCC 53921 and mutations and recombinants thereof. The integrated circuits are generally crushed to between 20 and -400 mesh before placement into theThis invention was made with Government support under Contract No. F33615-87-C-5303 awarded by the United States Air Force. The Government has certain rights in this invention.

Abstract: Disclosed is a high temperature process (e.g.>60.degree. C.) for leaching selected metal compounds e.g. gallium or germanium from ore containing those compounds. The method includes placing the ore into a culture medium containing bacteria. Bacteria capable of leaching the metal compounds from the ore leach the metals from the ore. The bacteria preferably used will be bacteria ATCC 53921 and mutations and recombinants thereof. The ore is generally crushed to between 20 and -400 mesh before placement into the culture medium cThis invention was made with Government support under Contract No. F33615-87-C-5303 awarded by the United Stated Air Force. The Government has certain rights in this invention.

Abstract: A process for the hydrometallurgical treatment of an indium chloride solution and at least one element selected from the group consisting of tin and antimony comprises the following steps: a) adjustment of the free chloride ion content by addition of alkaline or alkaline earth chloride or a mixture thereof and of their acidity by the addition of hydrochloric acid; b) bringing said indium chloride solution into contact with an organic phase containing dry trialkyl phosphate; c) extraction of said organic phase by bringing the latter into contact with a 0.1 to 3 N hydrochloric acid solution to obtain an indium chloride solution; d) basic extraction using an alkaline metal hydroxyde. Application to extractive metallurgy and recovery of indium and accompanying elements.

Abstract: A method of producing a .beta.-sialon fine powder which comprises using a silane compound represented by the general formula of SiH.sub.x Cl.sub.4-x (0.ltoreq.x.ltoreq.4) as a Si source, aluminum chloride as an Al source and an ether represented by the general formula of ROR' (R,R'=C.sub.y H.sub.2y+1, 1.ltoreq.y.ltoreq.5) as an oxygen source respectively, dissolving them in an organic solvent capable of dissolving them to obtain a solution, introducing ammonia gas into the solution to produce a precipitates, and burning the precipitates in a nonoxidative atmosphere. In the .beta.-sialon fine powder obtained by the method of the invention, respective elements of Si, Al, O and N are uniformly distributed in a chemical viewpoint. A high density high strength sintered body can be produced even at a relatively low temperature by using the .beta.-sialon fine powder.

Abstract: Aqueous effluent solutions containing metal cations may be treated with an extractant comprising an organophosphinic acid, a di-2-ethylhexyl phosphoric acid and/or an aliphatic amine to selectively separate chromium, nickel, cobalt, copper and lead cations from the aqueous solution. Typical extraction techniques include liquid-liquid extraction employing either mixer settlers or columns, liquid membrane extraction and selective supported membrane extraction.

Abstract: The invention relates to a process for the recovery of metal values contained in a ferric gangue.The process comprises the following stages:(a) dissolution of the metal values from the ferric gangue with sulphuric acid;(b) recovery of the metal value or values by a method which is known per se,(c) evaporation of the acid ferric solution resulting from stage (b) so as to increase the acidity to a value of between about 50 and 100%,(d) crystallization from this solution, at a temperature of between -10 and 50.degree. C., of a hydrated iron sulphate of formula Fe.sub.2 (SO.sub.4).sub.3.9H.sub.2 O.Application to the recovery of strategic metals.

Abstract: A process using an extractant, that consists on the one hand of an active component being substituted 8-hydroxyquinoline and on the other hand of by-products of the manufacture of said extractant, said process being characterized in that the extractant contains at least 90 wt % of the active component.

Abstract: A metal is dissolved by being brought into contact with at least one halogenated hydrocarbon in the presence of a cationic surfactant.

Abstract: The present invention relates to an aqueous ferric chloride leach process for the extraction of metal values from a metal-sulphide bearing material, the leach being carried out in the presence of a leaching aid chosen from among salts of diesters of sulphodicarboxylic acids. It, in particular, relates to the enhanced recovery of metal values from complex, metal-sulphide bearing materials such as, for example, fine grained, polymetallic sulphide ores, their concentrates or the like.

Abstract: The invention provides a hydrometallurgical process for recovering lead in essentially pure form from a sulphurized compound containing at least lead as a non-ferrous metal. The process involves treating the sulphurized compound with an aqueous lixiviating solution containing at least one chloride of a metal selected from the group consisting of copper, bismuth, antimony, arsenic, and silver, preferably cupric chloride, the quantity of said at least one chloride being less than or equal to that which is stoichiometrically required for the complete dissolution of the lead contained in the sulphurized compound, thereby to obtain a solution containing lead chloride and the chlorides of metals nobler than lead as impurities if originally present in the sulphurized lead compound, and an insoluble residue containing the sulphide of the metal of said at least one chloride, the sulphides of the non-ferrous metals originally present in the sulphurized compound, and free sulphur.

Abstract: A process for the treatment of flue dust from copper and lead smelters includes the steps of subjecting a slurry (10) of water and flue dust to a first caustic leach (12) to form a first liquids soluble sulfate solution (14) and a first solids portion (15), subjecting the solids portion to a second caustic leach (16) to solubilize lead and arsenic in a second liquid portion (22) and, selectively extracting the arsenic from the second liquid portion by precipitation (23).

Abstract: A method for eluting a metal adsorbed on a chelating agent with an eluent, which comprises using as the eluent an aqueous solution containing a water-soluble inorganic sulfide and a basic compound at concentrations of 0.005 to 3N and 0.1N or more, respectively.

Abstract: The invention relates to a hydrometallurgical process for the overall recovery of the components of exhausted lead-acid batteries, in a re-useable form, said components being mainly constituted by such materials as polypropylene, ebanite, PVC; by paste comprising lead sulphatized compounds; and by pure or alloyed metal lead, characterized in that it comprises the following steps:(a) battery crushing,(b) separation of paste by wet-screening,(c) separation of polypropylene by water floating,(d) separation of ebanite and PVC from pure or alloyed metal lead, by means of a first hydrodynamic separation,(e) separation of ebanite from PVC by a second hydrodynamic separation,(f) desulfurization of paste by carbonation by sodium carbonate, with pure sodium sulphate being obtained,(g) recovery of so-obtained pure sodium sulphate,(h) treatment of carbonated paste in order to recovery from it the lead, in pure metal form, by extraction by electrowinning.

Abstract: Metal ions contained in trace in an aqueous solution are extracted, for quantitative analysis by an ICP emission spectrometer, with an organic solvent supplemented by chelate compounds in an extraction vessel having a thin cylindrical upper portion, to form an organic layer containing the extracted metal ions over an aqueous layer. After extraction, water is supplied from the bottom of the vessel in an amount so that the interface between the organic and aqueous layers is positioned at a predetermined position of the thin, upper portion where a liquid withdrawal port is provided. The organic layer is recovered from the withdrawal port.

Abstract: A process for treating a first metal, manganese-containing ore comprising contacting the manganese-containing ore with an aqueous, acidic composition and a material containing at least one metal sulfide at conditions effective to (1) chemically reduce at least a portion of the manganese, (2) solubilize at least a portion of the metal from the metal sulfide, and (3) at least partially liberate the first metal from the ore; and recovering the first metal from the ore. The use of Thiobacillus ferrooxidans and/or added ferric ion in the contacting step are also disclosed.

Abstract: A process for recovering at least one first metal from a metal sulfide-containing ore comprising contacting the ore with an aqueous, acidic composition and at least one reducible manganese-containing material at conditions effective (1) to chemically reduce the manganese, (2) solubilize at least a portion of the metal from the sulfide, and (3) at least partially liberate the first metal from the ore; and recovering the first metal from the ore. The use of added ferric ion and/or Thiobacillus ferrooxidans bacteria in the above-noted contacting is also disclosed.

Abstract: A process is described for recovering tin from oxide or oxide/sulphide low-grade starting materials and concentrates containing little or relatively low concentrations of tin, in which such low-grade starting materials are mixed with KOH and decomposed at high temperatures. The decomposed substance is then leached with water, and metallic tin is separated out electrolytically in one or more stages from the lye. The electrolyte with reduced tin content is concentrated by evaporation, impurities being removed, and dehydrated. The potassium hydroxide solution recovered is re-used for decomposition.

Abstract: Iron is recovered from an iron-containing dust obtained in processing iron or steel by dissolving iron and bivalent metals present in the dust in an acid. Subsequently the iron is precipitated as iron hyroxide by adding an alkaline substance or ammonia to adjust the pH to 5 to 8. Before or during precipitation of any iron the bivalent metal ions present, such as zinc, cadmium and lead, are converted into a soluble complex by the addition of a complexing agent, preferred complexing agents being polyamines, particularly triethylene tetramine. The process may be conducted more than once in the same solution, thereby providing a final solution containing considerable amounts of zinc, cadmium, or other bivalent metals, which may be separated by boiling or precipitation.

Abstract: A process is provided for reducing the total concentration of heavy metals, notably lead, copper and zinc, naturally occurring in silica-rich sludge precipitated from geothermal brine in a brine handling system such as a geothermal brine electric generating plant. The process includes washing the sludge with hot water to displace any brine entrapped in the sludge, dewatering the washed sludge and leaching the silicious solids residue with hydrochloric acid having a concentration of between about 2 and about 9 weight percent and an acid-to-sludge weight ratio between about 0.10 and about 0.33. The acid-sludge mixture is heated to a temperature of at least about 50.degree. and the leaching time is at least about one hour. The leaching solution is separated from the leached sludge and the solids residue are washed with water. Preferably the water used in both washing steps is condensate of steam derived from the geothermal brine. Effluent from the process is preferably combined with the brine for reinjection.

Abstract: A method is provided for the removal of lead contaminants from ores and mineral concentrates, comprising leaching the concentrates, at elevated temperatures, with an aqueous solution containing an aminopolycarboxylic acid. After separating the solution from the concentrates, lead can be precipitated by treating the solution with a sulfide; the solution can be recycled for use as a leachant.

Abstract: This is a method for the complete leaching of the valuable metals in a metal sulphide material which contains copper, zinc, lead, silver and iron by the use of a solution which essentially contains cupric chloride/sulphates. After the valuable metals have been recovered, the solution is regenerated whereby ferrous chloride and cuprous chloride/sulphate is oxidized to a ferric hydroxide solid and a cupric chloride solution respectively. The regenerated solution is split into two part-solutions and returned to the process.One part-solution goes to a metathesis stage where the fresh metal sulphide material is added in large excess with respect to the part-solutions's content of copper. The result is that only the valuable metals like zinc, lead and silver are leached while copper and iron remain in the residue.The other part-solution goes to a leach stage where the residue from the metathesis stage is added.

Abstract: A process for selectively stripping and separating iron ions from an organic solvent (A) which comprises bringing the organic solvent (A) containing iron and zinc ions, and containing one or more compounds selected from the group consisting of alkyl phosphoric acid, alkyl-aryl phosphoric acid, alkyl thio phosphoric acid and alkyl-aryl thio phosphoric acid together with a petroleum hydrocarbon as a diluent, into contact with an aqueous solution containing NH.sub.4.sup.+ and F.sup.- ions so as to selectively strip the iron ions into the aqueous solution despite the coexistence of zinc ions.

Abstract: Metal values are separated from arsenic sulfide ores in a hydrometallurgical oxidation process using a balanced reactant slurry. The molar concentration of As and Sb in the reactant slurry is controlled with respect to the molar concentration of Cu, Pb, and Zn in the slurry so that, upon reacting, soluble arsenic compounds or toxic arsenic vapors are not formed.

Abstract: This invention relates to the development of a viable metallurgical process capable of treating low grade concentrates, bulk concentrates, dirty concentrates, or ore directly for the recovery of non-ferrous metals such as zinc, lead, copper, and precious metals and accordingly is significant to the development of massive fine grained sulphide ore bodies found throughout the world. The process involves the consecutive steps of sulphatizing roasting in a fluidized bed reactor, a two stage leach, metal recovery from solution by conventional processes such as electrowinning and precipitation, and recycling of residue wash waters and leach liquors containing high concentrations of iron and minor impurity elements to the roaster or a spray dryer for thermal decomposition. Simple and efficient rejection of iron from the circuit to residue as stable hematite is the net result of the recirculation and thermal decomposition.

Abstract: The present invention relates to a process for purifying flue gases developed during the combustion of waste materials and containing solids of various compositions as well as pollutant gases and heavy metals in gaseous form, wherein the primarily solid components are removed from the flue gas in a separating system and are collected as flue ashes and wherein the flue gas is washed for the purpose of binding the pollutant gases of the residual solids components, particularly in the slag.It is the object of the present invention to provide a process wherein, during flue gas purification, the gaseous heavy metal contaminants as well as the heavy metal contaminants which are present in the flue ash and in the slag in soluble form, can be removed from the flue gas purification process in the most compact form, with simultaneously achieving good, or even improved, initial purification of HCl, SO.sub.2. NO.sub.x. All other residues should be returnable for further use.

Abstract: A hydrometallurgical process is provided for separating heavy metal nuisance elements such as As, Sb, Bi, Sn and Pb from precious metals and/or selenium. The process can be used as a step in an overall hydrometallurgical process for treating refinery residues such as anode slimes for the separation and recovery of valuable metal values.

Abstract: A process is disclosed for the hydrometallurgical treatment of finely divided iron-containing steel plant dusts containing zinc, lead and such other metal values as calcium, manganese, silicon, magnesium, aluminum, cadmium, copper, and the like. The process is carried out by forming an aqueous slurry of the flue dust with a mixed lixiviant comprising HCl and H.sub.2 SO.sub.4, the amount of sulfate ion concentration being in excess of the chloride ion concentration and in stoichiometric excess of that required to sulfate substantially all of the lead and calcium present. The amount of chloride ion present as HCl should be sufficient to maintain the pH at about 1 to 4. The leaching is conducted at a temperature ranging from ambient to below the boiling point for a time at least sufficient to effect dissolution of at least zinc and other metal values and form a residue containing iron oxide, calcium sulfate and lead sulfate.

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