The invention provides a process of isolating or enriching a heavy metal present in a liquid medium. The process comprising the following steps: (a) incubating a suspension containing (i) particulate scrap metal, household waste and/or industrial waste containing a heavy metal in elemental form and (ii) biomass comprising a bacterium, or a combination of two or more bacteria, capable of binding the heavy metal; (b) separating the biomass having bound heavy metal from the suspension of step (a); and (c) isolating the heavy metal from the biomass separated in step (b).

The subject invention provides safe, environmentally-friendly, compositions and methods for extracting minerals and/or metals from ore. More specifically, the subject invention provides for bioleaching using a composition comprising one or more biosurfactant-producing microorganisms and/or microbial growth by-products. In specific embodiments, the composition comprises biosurfactant-producing yeasts and/or their growth by-products.

The invention relates to a method for removing metal and/or precious metal-containing depositions from substrates. The substrate is subjected to treatment with an organo amine protectant component P and an inorganic active component A. Component P may be formed in situ by reaction with component R. Component P is an organic amine and/or organic amine hydrochloride. Component A is an inorganic compound and component R is an organic compound that can be split along the CN bond by the component A into an organic amine. The metals in the form of organo-metallic complexes can be isolated and/or separated by means of different chemical reactions and/or biosorption.

A silica aggregate includes primary silica particles aggregated, the primary silica particles having an average particle size of 1 nm or more and less than 10 nm, the primary silica particles being crosslinked to each other by a bond containing a siloxane bond.

A process for recovery of one or more elements, selected from precious metals and chalcophile metals as herein defined, from materials containing precious and/or chalcophile metal/s, said process including: (i) a leaching step comprising contacting the material with an acidic solution containing a lixiviant comprising an aqueous amino acid-thiourea compound formed from an amino acid (as herein defined) and thiourea (as herein defined), in order to form a leachate containing the precious metal and/or chalcophile metal; and (ii) a recovery step comprising recovering the precious metal and/or chalcophile metal from the leachate.

The present invention relates to a method for selectively precipitating and extracting gold in aqueous solution by niacin. Aqueous Au.sup.3+ is precipitated selectively as it's complex from gold containing acidic mixtures by biomolecule niacin, with the formula [AuCl.sub.4].sup.[2Niacin+H].sup.+. After precipitation, the complex is separated from impurities by filtration. Recovered complex is reduced by using a reductant like sodium metabisulfite (Na.sub.2S.sub.2O.sub.5) to recover gold metal. The method is highly cost-effective, sustainable and recovers about 96.5% of gold in 2 minutes from an electronic waste composed of Au. Cu and Ni. The method is also employed to extract gold from nanomaterials waste generated in laboratories.

The invention relates to a method of recovering Pt or Ag or Pt and Ag from a sulfate solution on an electrode. In particular, the invention concerns a method for recovering Pt or Ag or Pt and Ag from base metal bearing process solution, particularly from a hydrometallurgical sacrificial metal bearing solution containing Zn and/or Ni. In general, the method of the present invention can be used for recovery of precious metals, which are dissolvable in sulfuric acid, from sulfate media based solutions. In addition to Pt and Ag, especially Pd should be mentioned.

Deposited precious metal(s) can be recovered from the electrode or the deposition containing electrode can be used as such.

The invention provides an assay for identifying a bacterium capable of binding elemental heavy metal, comprising the following steps: cultivating a test bacterium in a suitable first culture medium; immersing at least a surface portion of a test tool into the first culture medium for a second predetermined period of time, said surface portion being coated by elemental heavy metal, respectively; removing said test tool from said first culture medium and optionally rinsing the test tool; contacting a second culture medium with the surface portion coated by elemental heavy metal of said test tool removed in the previous step; and identifying the test bacterium as being capable of binding elemental heavy metal from growth of the test bacterium in said second culture medium.

The subject matter described herein includes a method for extracting a desired metal from a substance. The method includes contacting the substance with an alkaline leach to separate the desired metal from the substance, providing ultrasound energy and anodic current on a work face of the substance, etching the substance with the alkaline leach, thereby releasing the desired metal from the substance, and collecting the released desired metal.

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 or phosphoric 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.