US 12,735,769 B1 · Deployable multi-zone rotary-kiln system and method for recovery of gallium oxide from electronic waste

Abstract

A deployable system and method are provided for recovering gallium oxide from gallium-nitride-bearing electronic waste in a single, continuous, multi-zone rotary-kiln reactor. Shredded E-Waste is introduced through a sealed feed assembly into a refractory-lined kiln having a first zone operating at about 700° C.-900° C. for partial oxidation of organics and a second zone operating at about 1000° C.-1200° C. for oxidation of gallium nitride to gallium oxide. Controlled oxidant injection and kiln rotation of 0.25-3 rpm maintains residence times of 0.5-2 hours for complete conversion. An expanded velocity-reduction chamber separates oxidized solids from gases, while a downstream heat-recovery and dry-neutralization system removes acid gases and volatile metals without producing liquid effluent. The resulting porous gallium oxide is directly leachable to yield high-purity gallium. The modular, containerized design allows field deployment and scalability, and may also recover indium, tin, cobalt, lithium, and rare-earth oxides from other composite electronic wastes.

Claims24

Dependent claims

A method for recovering gallium oxide from electronic waste containing gallium nitride, comprising the steps of:

a) shredding and metering the electronic waste to form a controlled feed;
b) introducing the feed into a rotary-kiln reactor under conditions of limited oxidant supply to effect partial oxidation of organic constituents at a temperature between about 700° C. and 900° C., thereby leaving an inorganic residue;
c) transferring the inorganic residue to a higher-temperature zone of the same reactor and introducing oxidant to oxidize gallium nitride to gallium oxide at a temperature between about 1000° C. and 1200° C.;
d) rotating the reactor at a rate between about 0.25 rpm and 3 rpm to control the residence time of solids between about 0.5 hour and 2 hours;
e) discharging the oxidized solids into a velocity-reduction chamber to separate metals from process gases;
f) collecting the gallium-oxide-containing solids and cooling them to ambient temperature;
and
g) subjecting the cooled solids to acid leaching to produce a soluble gallium salt suitable for recovery of metallic gallium.

5 more elements

Dependencies are inferred from the claim text.

Deployable multi-zone rotary-kiln system and method for recovery of gallium oxide from electronic waste

Life of this patent

Deployable multi-zone rotary-kiln system and method for recovery of gallium oxide from electronic waste

Life of this patent

Abstract

Claims24