US 5,375,721 A · Apparatus for dry placer mining

Abstract

A dry placer mining machine and a belt assembly for use therewith. The machine concentrates metallic constituents from a gravel mix by fluidizing the mix with air which passes upwardly through the belt assembly, and moving the fluidized mix over the belt and applying an electrostatic charge thereto. The belt assembly is made up of a composite fabric belt member and a plurality of riffle members which extend transversely across this. The composite fabric belt member is constructed of non-conductive materials so as to minimize dissipation of the electrostatic charge, and this is made up of a finely woven cloth top layer, a reticulated foam middle layer, and a coarse mesh lower layer. The riffle members, in turn, are provided with insulation for preventing the electrostatic charge from being conducted away from the fabric belt member. The belt assembly is driven over the open upper end of a plenum chamber, and air pressure is supplied to this through a blower and ducting. The internal surfaces of these components are coated with an insulating material which enhances the build-up of electrostatic charge on the airflow.

Claims42

Dependent claims

A belt assembly for use in a dry placer mining machine which concentrates metallic constituents from a gravel mix by fluidizing said mix with a gas and separating said metallic constituents from said mix by moving said fluidized mix over said belt assembly and applying an electrostatic charge to said belt assembly, said belt assembly comprising:

a composite fabric belt member, said fabric belt member being configured so that said electrostatic charge is established on said belt member as said fluidizing gas passes therethrough, said fabric belt member being constructed substantially entirely of nonconductive materials so as to minimize dissipation of said electrostatic charge;
and
a plurality of riffle members attached to and extending transversely across said fabric belt member in spaced, generally parallel relationships so as to define a series of collection zones, each said riffle member comprising:
an electrical insulator portion interposed in a conductive path through said riffle member, from said belt member to a conductive structure which is mounted to said riffle member, so as to prevent dissipation of said electrostatic charge due to said charge being conducted away from said fabric belt member to said conductive structure through said riffle member.

1 more element

A dry placer mining machine for concentrating metallic constituents from a gravel mix by fluidizing said mix with a gas and separating said metallic constituents from said mix by moving said fluidized mix over a belt and applying an electrostatic charge thereto, said machine comprising:

a frame for supporting and guiding an endless separation belt along a closed path having an upwardly inclined segment for receiving a gravel mix containing a low concentration of metallic constituents;
an endless separation belt assembly, said belt assembly comprising:
a composite fabric belt member, said fabric belt member being configured so that said electrostatic charge is established on said belt as a fluidizing gas passes therethrough, said fabric belt member being constructed substantially entirely of nonconductive materials so as to minimize dissipation of said electrostatic charge;
and
a plurality of riffle members extending transversely across said fabric belt member in spaced, generally parallel relationships so as to define a series of collection zones, each said riffle member being attached to said fabric belt member and comprising insulating means for preventing dissipation of said electrostatic charge due to said charge being conducted away from said fabric belt member through said riffle members;
fluidizing means for passing said fluidizing gas upwardly through said fabric belt member of said separation belt assembly substantially uniformly along and about said upwardly inclined segment so as to fluidize said gravel mix and establish said electrostatic charge on said belt assembly;
and
drive means for driving said belt assembly along said closed path so that said fluidized gravel mix moves over said belt assembly and said electrostatic charge effectuates a substantial separation of said metallic constituents from said gravel mix and retention of said metallic constituents proximate said riffle members, whereby said metallic constituents are concentrated for collection.

5 more elements

Dependencies are inferred from the claim text.

Apparatus for dry placer mining

Life of this patent

Apparatus for dry placer mining

Life of this patent

Abstract

Claims42