A method for recovering a precious metal from a precious metal-containing waste catalyst includes the following steps: i) at least partially dissolving a precious metal-containing waste catalyst in an alkaline aqueous solution; ii) performing filtering to obtain a precious metal-containing filtrate and a precious metal; iii) treating the filtrate with a reducing agent; and iv) separating the precious metal from the filtrate after treatment, wherein step iii) is performed under a pressure of 8-12 bar at a temperature of 190-210° C. for 2-4 h. The method provided in the present invention has a simple process and a high recovery rate. The filtrate obtained from separation comprises a precious metal of 1 ppm or less by weight.

The invention discloses a method for cracking slag and smelting soot of the waste circuit board, belongs to the field of comprehensive recycling of valuable elements from typical soot of waste circuit boards, and particularly relates to a method for cracking slag and smelting soot of the waste circuit board for debromination and comprehensive recovery of copper and zinc. The method includes the following steps of: crushing and sorting, mixture roasting, reinforced leaching, replacement and silver precipitation, sulfuration and copper precipitation, and evaporation crystallization. Compared to traditional recycling technology, the purpose of treating two kinds of solid waste in a coupling mode through one recycling technology is achieved. Through mixed sulfuric acid roasting, the requirement of bromide synergistic removal of the waste circuit board cracking slag and smelting soot is met, and the purpose of selective conversion of copper and zinc is achieved.

Recovery of noble metals (including the recovery of gold and/or silver from gold and/or silver containing material) is generally described. The gold and/or silver can be recovered selectively, in some cases, such that gold and/or silver are at least partially separated from non-silver and/or non-gold material. Gold and/or silver may be recovered from material using mixtures of acids, in some instances. In some cases, the mixture can comprise nitric acid and at least one supplemental acid, such as sulfuric acid, phosphoric acid, and/or a sulfonic acid. The amount of nitric acid within the mixture can be, in some instances, relatively small compared to the amount of sulfuric acid or phosphoric acid within the mixture. In some cases, the recovery of gold and/or silver using the acid mixtures can be enhanced by transporting an electric current between an electrode and the gold and/or silver of the material. In some cases, acid mixtures can be used to recover silver from particular types of materials, such as material comprising silver metal and cadmium oxide and/or material comprising silver metal and tungsten metal.

Formation of CaSO.sub.4 and Fe.sub.2O.sub.3 containing deposits is reduced in a pressure oxidation autoclave and/or adjacent circuits during pressure oxidation of gold-containing ore. The gold-containing ore is combined with water to create an aqueous slurry that is heated and introduced into the autoclave. The method includes providing a scale inhibitor that is free of an organic polymer and includes an inorganic phosphate according to formula (I), (XPO.sub.3).sub.m, wherein X is Na, K, H, or combinations thereof, and m is at least about 6, an inorganic phosphate according to formula (II), Y.sub.n+2P.sub.nO.sub.3n+1, wherein Y is Na, K, H, an organic phosphonate; or combinations thereof, and n is at least about 6. The method includes the step of combining the scale inhibitor and at least one of the gold-containing ore, the water, and the aqueous slurry to reduce scale.

A method for producing copper metal from copper concentrates without generating waste by: (a) oxidizing copper concentrate; (b) cleaning and cooling the gases; (c) feeding to a reduction reactor; (d) cleaning the gases; (e) discharging hot powders and calcines into water; (f) performing magnetic separation; (g) thickening and filtering the magnetic fraction; (h) floating silica and inert materials; (i) thickening and filtering the silica and inert materials; (j) thickening and filtering the final concentrate containing the copper metal and noble metals; (k) smelting the final concentrate of copper and noble metals; and (l) recirculating ground smelt slag to a roasting reactor.

A method for recovering precious metal from an acidic aqueous solution containing dissolved precious metal and free chlorine, comprising the following successive steps: (1) combining a salt of a non-precious metal present in a low oxidation state as a solid or as an aqueous solution with the acidic aqueous solution to consume the free chlorine and form an acidic aqueous mixture, and (2) adding non-precious metal to the acidic aqueous mixture formed in step (1) to precipitate elementary precious metal.

Methods and systems for preparing ore for precious metal extraction is provided. For example, a method comprises crushing ore; grinding the crushed ore; screening the ground ore to separate ore particles into a first group of large ore particles and a first group of small ore particles; crushing the first group of large ore particles; screening the crushed ore to separate into a second group of large ore particles and a second group of small ore particles; separating the second group of small ore particles from the screen into a third group of large particles and a third group of small particles; milling the third group of large ore particles; separating milled particles into a fourth group of large particles and a fourth group of small particles; and sending the third and fourth group of small particles for further metal extraction processing.

Methods and systems for preparing ore for precious metal extraction is provided. For example, a method comprises crushing ore; grinding the crushed ore; screening the ground ore to separate ore particles into a first group of large ore particles and a first group of small ore particles; crushing the first group of large ore particles; screening the crushed ore to separate into a second group of large ore particles and a second group of small ore particles; separating the second group of small ore particles from the screen into a third group of large particles and a third group of small particles; milling the third group of large ore particles; separating milled particles into a fourth group of large particles and a fourth group of small particles; and sending the third and fourth group of small particles for further metal extraction processing.

Contemplated is a sensor system for use with a measuring device. The measuring device being of the type adapted to measure the volume of a desired solid component in a sample volume of a solid-liquid slurry obtained from either a carbon-in-pulp or carbon-in-leach process. The solid-liquid slurry comprises granular carbon particles, ore pulp, and water. The carbon-in-pulp or carbon-in-leach process includes at least one retention tank. The measurement device including: a receptacle for receiving the sample volume of the slurry; a screen provided in the receptacle for separating out the desired solid component from a remainder of the slurry. The solid component is retained in the receptacle to form a bed therein and the remainder is exhausted from the receptacle. The sensor system measures in either the retained solid component, or the exhausted remainder, or both one of: pH; dissolved oxygen; pulp density or carbon content.

Desirable methods for larger scale silver nanoplate synthesis are described along with methods for applying a noble metal coating onto the silver nanoplates to form coated silver nanoplates with a desirable absorption spectrum. The silver nanoplates are suitable for use in coatings for altering the hue of a transparent film. The hue adjustment can be particularly desirable for transparent conductive films.