Abstract: Disclosed is a method for clean metallurgy of molybdenum, including steps: 1) roasting molybdenite with calcium to obtain calcified molybdenum calcine, and leaching the calcified molybdenum calcine with an inorganic acid to obtain a molybdenum-containing inorganic acid leachate; 2) extracting molybdenum in the leachate with a cationic extractant to obtain an organic phase loaded with molybdyl cations and a raffinate; 3) using a hydrogen peroxide solution as a stripping agent to obtain a molybdenum stripping liquor; and 4) heating the molybdenum stripping liquor to dissociate peroxymolybdic acid therein so as to form a molybdic acid precipitate, and then calcining to obtain a molybdenum trioxide product. The method solves the problem of ammonia nitrogen wastewater production and can also be used for the enrichment and recovery of rhenium.

Abstract: The present invention relates to the field of catalysts, and provides a porous layered transition metal dichalcogenide (TMD) and a preparation method and use thereof. The preparation method includes the following steps: (1) mixing silica microspheres, a transition metal salt and an elemental chalcogen, and pressing to obtain a tablet, the silica microspheres having a same or different particle diameters; and (2) sintering the tablet under hydrogen, and removing the silica microspheres to obtain the porous layered TMD. The porous layered TMD prepared by the method of the present invention has a high lattice edge exposure, which provides more active sites and higher catalytic activity, so the porous layered TMD can effectively catalyze the oxidation of alcohols to aldehydes or sulfides to sulfoxides under visible light irradiation.

Abstract: A treatment method according to the present invention includes bringing a metal oxyfluoride of the general formula: MO(6-x)/2Fx (where 0<x<6; and M=W or Mo) into contact with a fluorine-containing gas at a reaction temperature higher than or equal to 0° C. and lower than 400° C., thereby converting the metal oxyfluoride to a metal hexafluoride of the general formula: MF6 (where M=W or Mo). This treatment method enables conversion of the metal oxyfluoride to the high vapor pressure compound without the use of a plasma generator and can be applied to cleaning of a metal fluoride production apparatus or cleaning of a film forming apparatus.

Abstract: A technique for exfoliating a transition metal dichalcogenide material to produce separated nano-scale platelets includes combining the transition metal dichalcogenide material with a liquid to form a slurry, wherein the transition metal dichalcogenide material includes layers of nano-scale platelets and has a general chemical formula MX2, and wherein M is a transition metal and X is sulfur, selenium, or tellurium. The slurry of the transition metal dichalcogenide material is treated with an oxidant to form peroxo-metalate intermediates on an edge region of the layers of nano-scale platelets of the transition metal dichalcogenide material. The peroxo-metalate intermediates is treated with a reducing agent to form negatively charged poly-oxo-metalates to induce separation of the transition metal dichalcogenide material into the separated nano-scale platelets of the transition metal dichalcogenide material.

Abstract: A device and a method for producing high-purity nano molybdenum trioxide are provided. The device comprises a raw material bin (1), a feeding machine (2), a subliming furnace (7), a first vent tube (24), a second vent tube (25), a spraying device (23) and a filtering assembly. The sublimated molybdenum trioxide is cooled with clean and dehumidified air so as to finally obtain the nano molybdenum trioxide, and the recycling mode is reliable, pollution-free and high in efficiency.

Abstract: A molybdenum disulfide sensor includes a flexible substrate, a patterned circuit layer and at least a molybdenum disulfide sheet. The flexible substrate has a gas flow channel. The patterned circuit layer is formed on the flexible substrate, and the patterned circuit layer includes a first electrode and a second electrode. The second electrode is faced toward the first electrode, and a gap is formed between the first electrode and the second electrode. The molybdenum disulfide sheet is located in the gap and is connected with the first electrode and the second electrode.

Abstract: Disclosed is a method for effectively leaching valuable metals such as vanadium and tungsten contained in a waste denitrification catalyst by using roasting and water leaching. According to the present invention, the method for leaching valuable metals contained in a waste denitrification catalyst comprises the steps of: (a) mixing a waste denitrification catalyst containing vanadium (V) and tungsten (W) in the form of an oxide with an alkali metal compound to form a mixture; (b) roasting the mixture to generate a roasting product comprising sodium vanadate (NaVO3) and sodium tungstate (Na2WO4); and (c) injecting the roasting product into water to water leach sodium vanadate and sodium tungstate in the form of a vanadate ion (VO3?) and a tungstate ion (WO42?).

Abstract: A method for the synthesis of molybdenum disulphide foam wherein the porosity of the foam can be controlled. The porosity of the foam is employed to adapt the foam to various processes and specific requirements. The foam molybdenum disulphide structures have internal cavities are interconnected to create a large processing surface area.

Abstract: An industrial microwave ultrasonic reactor has an inner wall liner. A microwave generation device is formed by microwave units distributed on an outer sidewall, or by a microwave pipe disposed outside the reactor and microwave units distributed on the microwave pipe. One end of the microwave pipe communicates with the bottom of the reactor via a connection pipe I, and the other end communicates with the top via a return pipe. A shield is disposed outside the microwave generation device to separate the microwave units from the outside, and a heat removal device is disposed outside the shield. An ultrasonic wave generation device is formed by 10 to 30 sets of ultrasonic pulse units disposed at intervals along the outer sidewall. Each set has 10 to 50 members distributed along the circumferential direction of the reactor. A stirring shaft is fixed below a stirring motor and extends into the reactor.

Abstract: A plasma-based processing method includes depositing a transition metal dichalcogenide (TMDC) material onto a substrate. The TMDC material is plasma treated in an oxygen containing ambient to oxidize the TMDC material to form oxidized dielectric TMDC material. The oxidized dielectric TMDC material has a higher electrical resistivity as compared an electrical resistivity of the TMDC material before the plasma treating, typically >103 times greater.

Abstract: A treatment method includes the steps of: Providing an initial supply of an ammonium octamolybdate precursor powder having a bi-modal particle size distribution; applying a quantity of solvent to the initial supply of ammonium octamolybdate precursor powder to form a moistened intermediate powder; and allowing the moistened intermediate powder to adsorb the applied solvent over a time period, the quantity of solvent applied and the time period being sufficient to form a treated ammonium octamolybdate powder composition having a substantially uni-modal particle size distribution.

Abstract: Enriched titanium hydrochloric acid extract residue is provided, for use as the feed stock in the preparation of titanium pigment by sulfuric acid process. The present invention belongs to the field of the preparation of titanium pigment and particularly, relates to the enriched titanium hydrochloric acid extract residue prepared from ilmenite by hydrochloric acid leaching, its use and the method of preparing titanium pigment. The method for preparing titanium pigment using the enriched titanium hydrochloric acid extract residue can effectively utilize the fine ilmenite in Panxi area (the utilization rate is almost 100%), obtain the titanium sulfate solution with an ultralow ratio of iron to titanium dioxide (Fe/TiO2) and double the throughput of digesting equipment.

Abstract: Disclosed is a method of pre-treating molybdenite containing copper. The method includes mixing molybdenite containing copper with sulfuric acid, performing a sulfation reaction through a heating process after the mixing process is performed, performing a water leaching process by putting and stirring water after the sulfation reaction is performed, separating a cake from liquid after the water leaching process is performed, and drying the separated cake.

Abstract: In one aspect, methods of purifying WC compositions are described herein. A method of purifying a WC composition comprises contacting the WC composition with an electrolyte solution comprising a cationic metal oxidant and oxidizing one or more metal impurities of the WC composition with the cationic metal oxidant to solubilize the one or more metal impurities in the electrolyte solution.

Abstract: A composite particle and a population of particles comprising a water-insoluble polyphosphate composition, methods of producing, and methods of using the same are provided. The polyphosphate composition may comprise at least one alkaline earth metal selected from calcium and magnesium and optionally at least one nutrient ion selected from the group consisting of potassium, ammonium, zinc, iron, manganese, copper, boron, chlorine, iodine, molybdenum, selenium or sulfur.

Abstract: The present invention refers to a method being easy to recover metals including nickel and aluminum from waste aluminum catalysts, thereby entirely promoting the recovering rate. Said method comprises: preparing and roasting a waste aluminum catalyst with sodium salts, and then obtaining a first solution comprising vanadium and molybdenum, and a dreg comprising nickel and aluminum through leaching and filtrating; collecting and mixing the dreg with alkali powders to obtain a mixture of the dreg and alkali powders, roasting the mixture at 300 to 1000° C. with aluminum in the dreg reacting with hydroxyl generated from the roasting of mixture and further generating aluminum hydroxide, and then obtaining a second solution comprising aluminum and a concentrate having nickel through another leaching and filtrating; and recovering aluminum from the second solution and recovering nickel from the concentrate.

Abstract: Various embodiments provide a process roasting a metal bearing material under oxidizing conditions to produce an oxidized metal bearing material, roasting the oxidized metal bearing material under reducing conditions to produce a roasted metal bearing material, leaching the roasted metal hearing material in a basic medium to yield a pregnant leach solution, conditioning the pregnant leach solution to thrill a preprocessed metal bearing material; and leaching the preprocessed metal bearing material in acid medium.

Abstract: A method of treating value bearing material comprising oxidized or surface oxidized mineral values includes the steps of crushing the value bearing material, contacting the crushed material! with a sulfide solution to sulfide the oxidized or surface oxidized mineral values, and adding ions of a selected base metal to the crushed value bearing material. The value bearing material may comprise oxidized or surface oxidized base metal or precious metal minerals. The crushed value bearing material is prepared as a slurry or pulp comprising from 15% to 40% solids and the remainder comprising water. The sulfide solution preferably comprises a soluble sulfidiser such as sodium hydrosulfide and the base-metal ion solution preferably comprises metal salt of base metals like copper or iron.

Abstract: Non-spherical siliceous particles having a plurality of porous branches are disclosed and claimed. The porous branches are randomly oriented and elongated, ring-like, and/or aggregated. An additive introduced during synthesis of the particles modifies pore volume and morphology. The tunability of the pore volume includes an inner diameter ranging from about 2 ? to about 50,000 ?. Synthesizing the particles includes mixing under constant or intermittent stirring in a reaction vessel an aqueous silicic acid solution with an acidic heel solution to form a mixture. The stirring may optionally be performed at a variable speed. An additive is introduced into the mixture at a controlled rate, wherein the additive imposes a pH change from a lower pH to a higher pH to the mixture to induce siliceous particle precipitation.

Abstract: The invention relates to a system and method for the substantially permanent biogeochemical stabilization of solids impacted with hexavalent chromium/Cr(VI), including chromite ore processing residue (“COPR”). The invention comprises a novel treatment method of adding amendment(s) to COPR or other chromate impacted solids for the purpose of (1) weathering COPR minerals (when present) to convert the minerals that control alkalinity of the COPR to non-alkaline forms and liberate incorporated hexavalent chromium (Cr(VI)) in the process; (2) providing a chemical reductant (ferrous iron) to rapidly and permanently reduce the available Cr(VI) to trivalent form (Cr(III)); and/or (3) supporting longer-term biogeochemical Cr(VI) reduction enhanced by recycling of the chemical reductant, ultimately rendering the material non-hazardous as measured by acceptable methods.

Abstract: A method for recycling metals from waste molybdic catalysts, comprises steps of leaching, by soaking a waste molybdic catalyst into a highly oxidized acid and conducting a reaction between sulfur in the waste molybdic catalyst and the acid to obtain sulfide and vaporizer, wherein metals in the waste molybdic catalyst are dissolved and oxidized by the acid to obtain a first solution and dregs; and refining, by further dissolving metals in the dregs into a second solution, and extracting metals in the waste molybdic catalyst from the first and second solution; wherein, the vaporizer obtained from the step of leaching is converted into highly oxidized acid and recycled in the step of leaching.

Abstract: A metal recovery process for heavy effluent from a hydroconversion process. The effluent contains unconverted residue and a solid carbonaceous material containing group 8-10 metal, group 6 metal, and vanadium and/or nickel, and the metals are recovered according to the invention.

Abstract: Compositions are provided that include nuclear fuel. Methods for treating nuclear fuel are provided which can include exposing the fuel to a carbonate-peroxide solution. Methods can also include exposing the fuel to an ammonium solution. Methods for acquiring molybdenum from a uranium comprising material are provided.

Abstract: One embodiment of method for extracting hexavalent chromium includes preparing a liquid sample by adding a fatty acid to a polymer material, adding water or an aqueous alkali solution to this sample, and extracting hexavalent chromium contained in the sample in the water or the aqueous alkali solution.

Abstract: In one embodiment, this invention is directed to a method of recovering metals from a metals bearing material comprising: reducing the particle size of at least a portion of the metals bearing material; mixing the metals bearing material in an acid solution to form a first slurry containing at least alkaline earth metal compounds; separating the at least alkaline earth metal compounds from the first slurry to form a first filtrate and a metals bearing material; leaching metals from the metals bearing material to form a pressure leach solution containing transition metals; precipitating and recovering transition metals from the pressure leach solution. In another aspect, the invention relates to a method for recovering metals from a deoiled and dried coal liquefaction residue that contains spent catalyst originating from a Group VIB metal sulfide catalyst.

Abstract: The present invention is directed to a process of treating fly ash and/or fly ash leachate to immobilize heavy metals contained in such fly ash and/or fly ash leachate, which process comprises treating such fly ash and/or fly ash leachate with a soluble ferrous compound under alkaline conditions. This process may be conducted in the absence of any pH modification, mixing (in the sense of a physical blending with a solid material), drying or heating steps, making it practical for treatment of alkaline fly ash (and other coal combustion by-products) which is currently stored in landfills or wet ash lagoons, particularly fly ash which has been recovered from flue gas streams treated with highly alkaline materials such as trona, bicarbonate or limestone and the like.

Abstract: A molecularly imprinted polymer ion exchange resin for selectively removing one or more inorganic ions in a liquid medium is disclosed and described. The exchange resin can include a bead having a porous structure and comprising a cross-linked molecularly imprinted polymer having molecular sized cavities adapted to selectively receive and bind a specific inorganic ion in a liquid medium. A process for preparing a molecularly imprinted polymer ion exchange resin can include (a) polymerizing a polmerizable mixture in the presence of an inorganic ion imprinting complex to form a bead, said inorganic ion imprinting complex including a ligand and an inorganic ion; and (b) removing the inorganic ions from the bead to form the molecularly imprinted polymer ion exchange resin, the bead having a porous structure and comprising a cross-linked molecularly imprinted polymer having molecular sized cavities adapted to selectively receive and bind a specific inorganic ion in an liquid medium.

Abstract: TiO2-supported catalysts include at least molybdenum or tungsten as active components for hydrotreating processes, in particular for the removal of sulfur and nitrogen compounds as well as metals out of crude oil fractions and for the hydrogenation of sulfur oxides.

Abstract: Compositions are provided that include nuclear fuel. Methods for treating nuclear fuel are provided which can include exposing the fuel to a carbonate-peroxide solution. Methods can also include exposing the fuel to an ammonium solution. Methods for acquiring molybdenum from a uranium comprising material are provided.

Abstract: A process for chlorinating ore, slag, mill scale, scrap, dust and other resources containing recoverable metals from the groups 4-6, 8-12, and 14 in the periodic table. The process comprises: a) forming a liquid fused salt melt consisting essentially of aluminum chloride and at least one other metal chloride selected from the group consisting of alkali metal chlorides and alkaline earth metal chlorides, wherein the aluminum chloride content in the liquid salt melt exceeds 10% by weight; b) introducing the recoverable metal resources into said liquid salt melt: c) reacting the aluminum chloride as chlorine donor with said recoverable metal resource to form metal chlorides, which are dissolved in the salt melt; and d) recovering the formed metal chlorides from the salt melt.

Abstract: The instant invention relates to a process and plant for the transformation of dangerous wastes containing chromium six as contaminant into non dangerous wastes that can be stored without special care and will be degraded in the environment without time limit. The process basically consists of milling, extracting chromium six in liquid phase and under controlled conditions of stirring, time and temperature, proceeding then, through reduction, to transform the chromium six in chromium three and then precipitating as chromium trioxide, through gasification. The solid resulting from the transformation process can be used as raw material for the manufacturing of firebricks or eventually for the manufacturing of bricks used in the building industry through a process not included in the instant description.

Abstract: A process for recovering metals from a stream rich in hydrocarbons and carbonaceous residues by means of a treatment section, characterized in that it comprises the following steps: sending said stream to a primary treatment, effected in one or more steps, wherein said stream is treated in the presence of a fluxant agent in a suitable apparatus, at a temperature ranging from 80 to 180° C., preferably from 100 to 160° C., and subjected to liquid/solid separation in order to obtain a clarified product essentially consisting of liquids and a cake (oilcake); possibly subjecting the separated cake to drying, in order to remove the hydrocarbon component having a boiling point lower than a temperature ranging from 300 to 350° C. from the cake; sending the cake, possibly dried, to a secondary thermal treatment comprising: a flameless pyrolysis of the cake effected between 400 and 800° C., preferably between 500 and 670° C.

Abstract: Stabilized precursor solutions can be used to form radiation inorganic coating materials. The precursor solutions generally comprise metal suboxide cations, peroxide-based ligands and polyatomic anions. Design of the precursor solutions can be performed to achieve a high level of stability of the precursor solutions. The resulting coating materials can be designed for patterning with a selected radiation, such as ultraviolet light, x-ray radiation or electron beam radiation. The radiation patterned coating material can have a high contrast with respect to material properties, such that development of a latent image can be successful to form lines with very low line-width roughness and adjacent structures with a very small pitch.

Abstract: A method of recovering vanadium, nickel and molybdenum from heavy crude oil refinery residues comprises pyrolysis and combustion of the residues at temperatures up to 900° C. to produce an ash, converting the ash to an aqueous slurry comprising sodium hydroxide as leading agent and hydrogen peroxide as oxidizer, and extracting vanadium, nickel and molybdenum salts and oxides from the slurry. Extraction processes for the metals are disclosed.

Abstract: A process is disclosed for separation and recovery of vanadium, molybdenum, iron, tungsten, cobalt and nickel from alumina-based materials, mattes, ores, manufacturing by-products and waste. These elements are oxidized. The oxides are reacted with gaseous HCl to form volatile chloride-bearing compounds that subsequently sublimate. The volatile compounds are condensed in a downward-stepped thermal gradient that allows collection of moderate to high purity compounds of individual elements with exception of a nickel-cobalt co-condensate. Nickel is separated from cobalt by precipitation of nickel chloride from concentrated HCl pressurized with gaseous HCl.

Abstract: A method of recovering rhenium (Re) and other metals from Re-bearing materials in the form of ammonium perrhenate having at least the step of adding Re-bearing materials into a leaching slurry. Additionally, the method has the step of adjusting the pH of the slurry to obtain Re in soluble form in a metal salt solution and insoluble residues; filtering the metal salt solution to remove the insoluble residues; selectively precipitating Re from the metal salt solution; filtering the Re precipitate from the metal salt solution to obtain a Re filtercake; and formulating and drying the Re filtercake to obtain a Re sulfide product. The method further has the step of combining the Re sulfide product with a Molybdenum (Mo) concentrate containing Re to obtain a Mo/Re concentrate; roasting the Mo/Re concentrate to obtain Mo oxide product and a flue gas containing Re; and treating the flue gas containing Re to obtain ammonium perrhenate.

Abstract: A process for digesting molybdenum oxide concentrates includes suspending a molybdenum-containing starting material in an aqueous solution so as to obtain a suspension. While stirring, an oxidizing agent and an alkali solution of at least one alkali metal are metered to the suspension so as to set a pH and produce a product having a molybdenum content of at least 98% of the molybdenum-containing starting material. The alkali metal is selected from the group consisting of Na, K and Li.

Abstract: A method of recovering minerals from hydrocarbonaceous materials can include forming a constructed permeability control infrastructure. This constructed infrastructure defines a substantially encapsulated volume. A comminuted hydrocarbonaceous material can be introduced into the control infrastructure to form a permeable body of hydrocarbonaceous material. The permeable body can be contacted with an agent sufficient to remove minerals therefrom. The agent is typically a solution containing a solvent, leachant, chelating agent and the like via which minerals can be removed having value, toxic minerals, radioactive minerals and the like.

Abstract: Processes for reducing hexavalent chromium, Cr(VI) in a chromite ore processing residue matrix and processes for analyzing and determining effective treatment are disclosed.

Abstract: A method of sequestering carbon dioxide emissions during recovery of hydrocarbons from hydrocarbonaceous materials can include forming a constructed permeability control infrastructure. This constructed infrastructure defines a substantially encapsulated volume. A comminuted hydrocarbonaceous material can be introduced into the control infrastructure to form a permeable body of hydrocarbonaceous material. The permeable body can be heated sufficient to remove hydrocarbons therefrom. During heating, the hydrocarbonaceous material is substantially stationary as the constructed infrastructure is a fixed structure. Additionally, during heating, any carbon dioxide that is produced can be sequestered. Removed hydrocarbons can be collected for further processing, use in the process, and/or use as recovered.

Abstract: A process for the recovery of high purity boehmite with controlled pore size from spent hydroprocessing catalyst includes the step of treating the spent hydroprocessing catalyst composition in order to get recovery of the aluminas after extracting the valuable metals. The process permits easy and resourceful recovery of high quality boehmite from waste catalyst, which can be further used as hydroprocessing catalyst carrier having a pore structure almost identical or better than that used in heavy oil hydroprocessing catalysts. Such catalyst carrier is required to have high pore volume, macro-porosity, high strength and optimum surface area for active metal dispersion. The treating steps include process steps such as decoking, roasting, leaching, dissolving, digestion, precipitation, washing, stripping, and the like. The recovery steps include digestion, hydrothermal treatment, flocculation or precipitation, filtration, drying, calcination and the like.

Abstract: The present disclosure is a process for the recycling of tungsten carbide alloy. Tungsten carbide alloy scrap is heated in an oxidizing atmosphere and the oxidized material is pulverized by grinding. The powder material is treated with a carburizing mixture for reducing and carburizing the powdered tungsten oxides and other metal oxides. The method is cost effective and environment friendly.

Abstract: A process is disclosed for separation and recovery of vanadium, molybdenum, iron, tungsten, cobalt and nickel from alumina-based materials, mattes, ores, manufacturing by-products and waste. These elements are oxidized. The oxides are reacted with gaseous HCl to form volatile chloride-bearing compounds that subsequently sublimate. The volatile compounds are condensed in a downward-stepped thermal gradient that allows collection of moderate to high purity compounds of individual elements with exception of a nickel-cobalt co-condensate. Nickel is separated from cobalt by precipitation of nickel chloride from concentrated HCl pressurized with gaseous HCl.

Abstract: Methods for recovering base metals, including, among other metals, molybdenum and nickel, from metal sulfides containing a Group VIB metal and a Group VIII metal. Generally, the methods comprise: contacting metal sulfides with a leaching solution containing ammonia and air to dissolve the metals into the leaching solution, forming a slurry containing soluble complexes of the metals, ammonium sulphate and solid residue containing ammonium metavanadate and any carbonaceous materials. The solid residue containing ammonium metavanadate and carbonaceous materials is then separated from the slurry and metal complexes are precipitated from the slurry by adjusting the pH. A second slurry may be formed comprising a second solid residue and a primary filtrate comprising ammonium sulfate solution that is substantially free of metals.

Abstract: The instant invention relates to a process and plant for the transformation of dangerous wastes containing chromium six as contaminant into non dangerous wastes that can be stored without special care and will be degraded in the environment without time limit. The process basically consists of milling, extracting chromium six in liquid phase and under controlled conditions of stirring, time and temperature, proceeding then, through reduction, to transform the chromium six in chromium three and then precipitating as chromium trioxide, through gasification. The solid resulting from the transformation process can be used as raw material for the manufacturing of firebricks or eventually for the manufacturing of bricks used in the building industry through a process not included in the instant description.

Abstract: A method of isolating a radioisotope according to example embodiments may include vaporizing a source compound containing a first isotope and a second isotope of an element, wherein the second isotope may have at least one of therapeutic and diagnostic properties when used as a radiopharmaceutical. The vaporized source compound may be ionized to form charged particles of the first and second isotopes. The charged particles may be separated to isolate the particles of the second isotope. The isolated charged particles of the second isotope may be collected with an oppositely-charged collector. Accordingly, the isolated second isotope may be used to produce therapeutic and/or diagnostic radiopharmaceuticals having higher specific activity.

Abstract: An improved process for the separation of different metal values from raw materials, and an apparatus for carrying out such processes are disclosed.

Abstract: Proppants which can be used to prop open subterranean formation fractions are described. Proppant formulations which use one or more proppants of the present invention are described, as well as methods to prop open subterranean formation fractions, and other uses for the proppants and methods of making the proppants.

Abstract: The present teachings are directed methods of producing tungsten-containing nanoparticles, specifically tungsten nanoparticles and tungsten oxide nanoparticles with an average particle size of less than about five nanometers.

Abstract: The instant invention relates to a process and plant for the transformation of dangerous wastes containing chromium six as contaminant into non dangerous wastes that can be stored without special care and will be degraded in the environment without time limit. The process basically consists of milling, extracting chromium six in liquid phase and under controlled conditions of stirring, time and temperature, proceeding then, through reduction, to transform the chromium six in chromium three and then precipitating as chromium trioxide, through gasification. The solid resulting from the transformation process can be used as raw material for the manufacturing of firebricks or eventually for the manufacturing of bricks used in the building industry through a process not included in the instant description.