Patent Description:
Metals are widespread in the natural world. Metals, commonly used in life, are one of the most important and mostly applied substances in modern industry. Metal exploitation and smelting not only brings an impact to the environment, but also consumes <NUM>%-<NUM>% of global energy supply. Recycling consumes less energy than primary production of metals, and reduces overall impact on places where mines are exploited. However, constrained by the process and recycling cost, the recovery rateof metals remains at a relatively low level. In particular, noble metals are usually dissolved with nitrohydrochloric acid. Such method hurts environment, and results in very high recycling cost and serious pollution. Therefore, an environmentally-friendly method is in an urgent need for metal refining and recycling. Photocatalysis has great attention from scientific researchers in virtue of advantages in moderate reaction conditions and direct conversion from solar energy into chemical energy, and shows a great application prospect in fields of energy sources and environmental protection. Photocatalysis for metal dissolution brings about an every important opportunity for protection and energy utilization, and makes contribution to transition to a low-carbon and resource-saving green economy.

Chinese Patent, No.<CIT>, discloses a method for quickly activating and dissolving insoluble noble metals. The method takes nitrohydrochloric acid or acidic sodium chlorate as a solvent to quickly dissolve insoluble noble metals such as iridium and rhodium. However, the activation temperature reaches <NUM>-<NUM>, which is a rigorous condition. In addition, the highly corrosive nitrohydrochloric acid is used in the process. The Chinese patent, No. <CIT>, discloses a method for quickly dissolving insoluble metal iridium. According to this method, iridium powder and hydrochloric acid are added into a reactor, then stirred while chlorine is introduced to maintain a reaction, and next chlorine removal and liquid-solid separation are carried out. Such method features complicated steps, and temperature rise and pressurization in progress.

<CIT> discloses a method involving agglomeration of mineral raw material, leaching of gold and further extraction of gold from the solution. Prior to leaching, fractional separation of mineral raw material is performed so that slurry fraction and the main volume of large-sized agglomerated mineral raw material is obtained. Slurry fraction is subject to photocatalytic cuvette leaching with mixed alkaline hypochlorite and hydrochloride solutions. Leaching of gold is performed from the main volume of large-sized agglomerated mineral raw material in stages using the solutions supplied through perforated pipes. Initially, leaching is performed in penetration mode using a concentrated cyanide solution. Then, after exposure period in diffusion mode, leaching is performed by supplying water and compressed air or weak solution of cyanides through perforated pipes.

The objective of the present invention is to provide a method for dissolving metals by photocatalysis under a moderate and environmentally-friendly condition to overcome defects in the prior art.

The objective of the present invention can be achieved by technical solution as defined in the appended claims.

All catalysts used in the present invention are commercially available catalysts or those disclosed in this field.

According to the present invention, the cyanide includes one or several ones of acrylonitrile, acetonitrile, phenylacetonitrile, cyanoacetic acid, malononitrile, benzyl cyanide and melamine; and the organic chloride include one or several ones of dichloromethane, trichlormethane, dichloroethylene, trichloroethane and tetrachlormethane. Further, the mass ratio of the cyanide to the organic chloride is <NUM> to <NUM> : <NUM> to <NUM>, preferably <NUM> to <NUM> : <NUM> to <NUM>; further preferably <NUM> to <NUM> : <NUM> to <NUM>.

Those two substances are far less toxic than the inorganic cyanide, environmentally-friendly and low in cost.

Compared with the prior method, the present invention has the following advantages:.

The present invention is further described in detail in conjunction with the attached drawings and specific embodiment.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> mixed-phase titanium dioxide photocatalyst was added. Ultraviolet irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<FIG> are sample diagrams before and after the dissolution reaction, respectively. It can be seen that, the sample was gray black before dissolution and was white after the dissolution reaction from <FIG>; and ICP test data in <FIG> also apparently show that the ratio of platinum in the liquid increased continuously (a small amount of solution was evaporated to obtain dry solvent, and then water was added in an amount equivalent to that of the solvent to dilute the solvent for testing).

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> mixed-phase titanium dioxide photocatalyst was added. Visible-light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> mixed-phase titanium dioxide photocatalyst was added. Visible light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and trichlorethanol (<NUM>:<NUM>). Then, <NUM> mixed-phase titanium dioxide photocatalyst was added. Ultraviolet irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and trichlormethane (<NUM>:<NUM>). Then, <NUM> commercial mixed-phase titanium dioxide catalyst was added. Ultraviolet irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and tetrachlormethane (<NUM>:<NUM>). Then, <NUM> commercial mixed-phase titanium dioxide catalyst was added. Ultraviolet irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of phenylacetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> commercial mixed-phase titanium dioxide catalyst was added. Ultraviolet irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of phenylacetonitrile and trichlorethanol (<NUM>:<NUM>). Then, <NUM> commercial mixed-phase titanium dioxide catalyst was added. Ultraviolet irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of phenylacetonitrile and trichlormethane (<NUM>:<NUM>). Then, <NUM> commercial mixed-phase titanium dioxide catalyst was added. Ultraviolet irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of phenylacetonitrile and tetrachlormethane (<NUM>:<NUM>). Then, <NUM> commercial mixed-phase titanium dioxide catalyst was added. Ultraviolet irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). <NUM> commercial mixed-phase titanium dioxide catalyst was added. Ultraviolet irradiation proceeded for <NUM> in an atmosphere with <NUM>% of oxygen. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> commercial mixed-phase titanium dioxide catalyst was added. Ultraviolet irradiation proceeded for <NUM> in an atmosphere with <NUM>% of oxygen. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> commercial mixed-phase titanium dioxide catalyst was added. Ultraviolet irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of palladium was dispersed in <NUM> mixed solution of acrylonitrile and trichlorethanol (<NUM>:<NUM>). Then, <NUM> commercial mixed-phase titanium dioxide catalyst was added. Next, a gas containing <NUM>% of oxygen was introduced. Irradiation by ultraviolet light with a <NUM> wavelength proceeded for <NUM>. The dissolution rate of palladium was <NUM>%.

<NUM> material containing <NUM>% of rhodium was dispersed in <NUM> mixed solution of malononitrile and trichlormethane (<NUM>:<NUM>). Then, <NUM> mixed-phase titanium dioxide catalyst was added. Next, a gas containing <NUM>% of oxygen was introduced. Irradiation by deep ultraviolet light with a <NUM> wavelength proceeded for <NUM>. The dissolution rate of rhodium was <NUM>%.

<NUM> material containing <NUM>% of iridium was dispersed in <NUM> mixed solution of benzyl cyanide and dichloroethylene (<NUM>:<NUM>). Then, <NUM> commercial mixed-phase titanium dioxide catalyst was added. Next, a gas containing <NUM>% of oxygen was introduced. Irradiation by ultraviolet light with a <NUM> wavelength proceeded for <NUM>. The dissolution rate of iridium was <NUM>%.

<NUM> material containing <NUM>% of gold was dispersed in <NUM> mixed solution of cyanoacetic acid and dichloroethylene (<NUM>:<NUM>). Then, <NUM> commercial mixed-phase titanium dioxide catalyst was added. Next, a gas containing <NUM>% of oxygen was introduced. Irradiation by ultraviolet light with a <NUM> wavelength proceeded for <NUM>. The dissolution rate of gold was <NUM>%.

<NUM> material containing <NUM>% of silver was dispersed in <NUM> mixed solution of melamine and dichloromethane (<NUM>:<NUM>). Then, <NUM> cadmium sulfide catalyst was added. Next, a gas containing <NUM>% of oxygen was introduced. Irradiation by visible light with a <NUM> wavelength proceeded for <NUM>. The dissolution rate of silver was <NUM>%.

<NUM> material containing <NUM>% of copper was dispersed in <NUM> mixed solution of acrylonitrile and trichlormethane (<NUM>:<NUM>). Then, <NUM> cadmium sulfide catalyst was added. Next, a gas containing <NUM>% of oxygen was introduced. Irradiation by visible light with a <NUM> wavelength proceeded for <NUM>. The dissolution rate of copper was <NUM>%.

<NUM> material containing <NUM>% of iron was dispersed in <NUM> mixed solution of acrylonitrile and trichlormethane (<NUM>:<NUM>). Then, <NUM> cadmium sulfide catalyst was added. Next, a gas containing <NUM>% of oxygen was introduced. Irradiation by visible light with a <NUM> wavelength proceeded for <NUM>. The dissolution rate of iron was <NUM>%.

<NUM> material containing <NUM>% of nickel was dispersed in <NUM> mixed solution of acrylonitrile and trichlormethane (<NUM>:<NUM>). Then, <NUM> cadmium sulfide catalyst was added. Next, ozone was introduced. Irradiation by visible light with a <NUM> wavelength proceeded for <NUM>. The dissolution rate of nickel was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> zinc porphyrin (Zn-porphyrin) catalyst was added. Visible-light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> porphyrin-based metallic organic compound (PCN-<NUM>) catalyst was added. Visible-light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> self-assembled porphyrin nano-sheet (SA-TCPP) catalyst was added. Visible-light irradiation proceeded in airfor <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> porphyrin loaded titanium dioxide (TCPP-TiO2) catalyst was added. Visible-light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> titanium dioxide (OV-TiO2) rich in oxygen defects catalyst was added. Visible-light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> hydroxyl modified titanium dioxide (OH-TiO2) catalyst was added. Visible-light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> two-dimensional titanium dioxide (2D-TiO2) catalyst was added. Visible-light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> titanium-dioxide and amino-modified metallic organic compound (TiO<NUM>@NH2-MIL-<NUM>) catalyst was added. Visible-light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> nitrogen doped titanium dioxide (N-TiO2) catalyst was added. Visible-light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> titanium dioxide (H-TiO<NUM>-x) rich in trivalent titanium ions catalyst was added. Visible-light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of <NUM> acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> anatase-phase titanium dioxide catalyst was added. Ultraviolet irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> molybdenum disulfide loaded titanium dioxide (MoS2/TiO2) catalyst was added. Visible-light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> a compound of molybdenum disulfide and cadmium sulfide (MoS2/CdS) compound catalyst was added. Visible-light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> cadmium sulfide quantum dots (CdS QDs) liquid catalyst was added. Visible light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> in-situ vulcanized oxide (W2S/WO3) catalyst was added. Visible-light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> phosphorus-doped indium oxide (P-In2O3) catalyst was added. Visible-light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> carbon nitride (g-C<NUM>Nx) with nitrogen defects catalyst was added. Visible-light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> carbon-dots modified carbon nitride (C Dots-C3N4) catalyst was added. Visible-light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> enzyme catalyst was added. Visible-light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> compound catalyst of organic optical system and inorganic compound (PSII/Ru2S3/CdS) was added. Visible-light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> bismuth bromide nanosheets with (<NUM>) face exposed (BiOBr nanosheets) catalyst was added. Visible-light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> bismuth bromide with defects (Bi<NUM>O<NUM>Br) catalyst was added. Visible-light irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> zinc oxide catalyst was added. Ultraviolet irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> copper oxide catalyst was added. Ultraviolet irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> bismuth oxide catalyst was added. Ultraviolet irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

<NUM> material containing <NUM>% of platinum was dispersed in <NUM> mixed solution of acetonitrile and dichloromethane (<NUM>:<NUM>). Then, <NUM> ferric oxide catalyst was added. Ultraviolet irradiation proceeded in air for <NUM>. The dissolution rate of platinum was <NUM>%.

Claim 1:
A method for dissolving metals by photocatalysis, characterized in that the method comprises steps of dispersing a metal-containing material to be dissolved in a mixed solution containing a photocatalyst and further comprising cyanide and organic chloride, and performing irradiation for a period of time to dissolve the metals, and wherein the light wavelength of the irradiation is <NUM> - <NUM>, characterized in that the cyanide comprises one or several ones of acrylonitrile, acetonitrile, phenylacetonitrile, cyanoacetic acid, malononitrile, benzyl cyanide and melamine; and characterized in that the organic chloride includes one or several ones of dichloromethane, trichlormethane, dichloroethylene, trichloroethane, trichlorethanol and tetrachlormethane, and performing irradiation for a period of time to dissolve metals.