Provided is a process for recovering metals from solid radioactive waste, preferably uranium, cesium, mercury, thorium, rare earths or combinations thereof. The process comprises a leaching step and a separation step. The leaching step comprises contacting the solid radioactive waste with an aqueous inorganic acid and a leaching salt to produce a mixture of a metal-rich leachate and a metal-poor waste, which are separated in the separation step. Also provided is a process for recovering metals from solid radioactive waste comprising an attrition step, a leaching step, a washing step, a combination step and a recovery step.

A system and method for treating cement kiln dust is provided. The method includes the steps of receiving cement kiln dust (CKD) from a kiln; heating the collected CKD; forming a gas stream of vaporized metal and CKD by sufficient heating to separate at least one heavy metal from the collected CKD stream to create a cleaned CKD stream and a metal stream; providing a water soluble alkaline-earth metal polysulfide; combining the heavy metal stream with the water soluble alkaline-earth metal sulfide to create a combined stream; and removing at least a portion of one heavy metal from the combined stream.

A system and method for treating cement kiln dust is provided. The method includes the steps of receiving cement kiln dust (CKD) from a kiln; heating the collected CKD; forming a gas stream of vaporized metal and CKD by sufficient heating to separate at least one heavy metal from the collected CKD stream to create a cleaned CKD stream and a metal stream; providing a water soluble alkaline-earth metal polysulfide; combining the heavy metal stream with the water soluble alkaline-earth metal sulfide to create a combined stream; and removing at least a portion of one heavy metal from the combined stream.

A method for producing a catalyst using an additive layer method includes: (i) forming a layer of a powdered catalyst or catalyst support material, (ii) binding or fusing the powder in said layer according to a predetermined pattern, (iii) repeating (i) and (ii) layer upon layer to form a shaped unit, and (iv) optionally applying a catalytic material to said shaped unit.

A method for producing a catalyst using an additive layer method includes: (i) forming a layer of a powdered catalyst or catalyst support material, (ii) binding or fusing the powder in said layer according to a predetermined pattern, (iii) repeating (i) and (ii) layer upon layer to form a shaped unit, and (iv) optionally applying a catalytic material to said shaped unit.

Disclosed is selective removal of mercury from aqueous feeds also including precious metals. In particular, the present invention is useful for removal of mercury from processing waters produced during precious metal mining processes. The process includes contacting the aqueous feed solution with a solid sorbent material including thiol and/or thiolate functional groups, wherein (i) the aqueous feed solution includes at least 10 ppm of free cyanide ions; and/or (ii) the sorbent material is contacted with an aqueous cyanide solution after contact with the aqueous feed solution to selectively desorb precious metal from the sorbent material.

Disclosed is selective removal of mercury from aqueous feeds also including precious metals. In particular, the present invention is useful for removal of mercury from processing waters produced during precious metal mining processes. The process includes contacting the aqueous feed solution with a solid sorbent material including thiol and/or thiolate functional groups, wherein (i) the aqueous feed solution includes at least 10 ppm of free cyanide ions; and/or (ii) the sorbent material is contacted with an aqueous cyanide solution after contact with the aqueous feed solution to selectively desorb precious metal from the sorbent material.

A process of extracting metals from a wet mass includes a step A of concentrating the metals in a carbonaceous solid with a thermochemical treatment of the wet mass, with the ancillary production of a treatment gas; a step B of thermochemical decomposition of the carbonaceous solid in an atmosphere constituted by an operating gas which contains oxygen in substoichiometric quantity to carry out the thermochemical decomposition in order to promote a combination of the metals with substances present in the carbonaceous solid to form salts and others solid compounds and to concentrate the latter in residual ashes of the carbonaceous solid at the same time providing for the formation of a combustible synthesis gas comprising hydrocarbons from the carbonaceous solid; and a step C of extraction of the metals from the ashes produced.

A process of extracting metals from a wet mass includes a step A of concentrating the metals in a carbonaceous solid with a thermochemical treatment of the wet mass, with the ancillary production of a treatment gas; a step B of thermochemical decomposition of the carbonaceous solid in an atmosphere constituted by an operating gas which contains oxygen in substoichiometric quantity to carry out the thermochemical decomposition in order to promote a combination of the metals with substances present in the carbonaceous solid to form salts and others solid compounds and to concentrate the latter in residual ashes of the carbonaceous solid at the same time providing for the formation of a combustible synthesis gas comprising hydrocarbons from the carbonaceous solid; and a step C of extraction of the metals from the ashes produced.

A process for separating one or more elements among the rare-earth elements from other metals in columns 4 to 14 of the Periodic Table of the Elements, in admixture in aqueous solution. The process uses a polyethyleneimine-CS2 adduct in the form of a salt and involves liquid/solid separation to obtain a solid predominantly containing the rare-earth elements.