The Bishop Gold Mill
NorthBay Resources owns and operates a permitted gold mill in Bishop, California.
This facility processes up to 100 tons of Gold Ore per day.
Gold Mill Details:
96-ton per day flotation mill. Processing capacity for ores.
Tailings Facility: Class A lined tailings facility. Approval of water license.
Regulatory Approvals:
Plan of Operation approved by US Bureau of Land Management.
Completion of the California Environmental Quality Act (CEQA) assessment.
On-Site Facilities:
power. Mechanical building.
Fully equipped assay lab. Office trailer.
Site well and monitoring wells.
Location
Location and context:
The Bishop Mill Project is situated in Inyo County, Owens Valley, northeast of Bishop, California.
Proyect Area Location:
The Bishop Mill site (Project area) is approximately 1 mile west of State Route (SR) 6 on Rudolph Road.
It is situated around 9 miles northeast of the town of Bishop, California.
Access Roads:
Rudolph Road, an existing improved dirt road, extends westerly from SR 6 for about 1 mile.
The road leads to the power line and mill-site access road.
The mill-site access road travels approximately half a mile southerly to the Project area entrance.
Land Ownership and Administration:
The site falls within public lands managed by the U.S. Department of the Interior, Bureau of Land Management, Bishop Field Office (BLM).
Specifically located within the SW quarter of section 4, Township 6 South, Range 33 East, Mount Diablo Baseline and Meridian.
Mill-Site Claims:
The Project area is covered by three mill-site claims controlled by the Project Applicant.
The total area of the mill site claims is 161.33 acres.
Active Project Area:
The current active Project area encompasses 9.1 acres of the total mill site claims area.
Ore Handling:
Ore off-loaded at existing concrete ore patio or temporary ore stockpile area northwest of the patio.
Raw ore loaded into ore feed bin (25-ton capacity) by front end loader.
Gravity-fed to mill at approx. 4 tons per hour or 96 tons per 24- hour shift.
Crushing and milling:
Ore crushed and milled to approx. minus 10 mesh.
Jigging Concentration:
Coarse concentrates dried and bagged for off-site refining.
Jigging process generates tailings mixed with water and reagent chemicals:
Xanthate 350 (general collector).
Aero 208 (free gold collector).
Aero 31 (sulfide collector).
Soda ash added to maintain near neutral pH.
Resulting chemically charged ore slurry is 30% solids.
Flotation Process:
Ore slurry transferred to flotation cells.
Aero Froth, a flotation agent, added for metallic particle recovery.
Agitated air-infused froth created, bringing metallic particles to cell surface.
Frothed metallic particles collected by each cell and transported to conditioner tank.
Flotation Process:
Concentrate containing reagents and precious metals piped to conditioner tank.
Dewatered to recycle additive chemicals into processing system.
Further dewatered at Leaf/Disk filter.
Concentrate Preparation for Shipping:
Concentrate filter material dried to around 10% moisture content.
Loaded in drums or flexible intermediate bulk container sacks.
Shipped off-site to refinery.
Waste Managenment Unit
Tailings Processing:
Tailings from flotation cells directed to Launderer tray.
Surfactant (Shaklee’s Basic H) added to tray.
Basic H breaks down remaining flotation reagents.
Heavy metal particles sink, preparing ore slurry for Diester gravity recovery shaker table.
Gravity Recovery:
Diester shaker table recovers larger or heavier metallic particles not captured in flotation process.
Concentrate Handling:
Shaker table concentrates sent to concentrate thickener tank.
Concentrates dewatered, filtered, and processed through concentrate dryer.
Dried concentrate shipped off-site for refining.
Tailings Disposal:
Rejects from Deister table are tailings.
Tailings piped to Waste Management Unit (WMU) for disposal.
Water Management:
Tailings piped to tailings impoundment for settling.
Water re-circulated to mill for reuse.
Flow Chart
Site Plan
Equipment
Primary Ore Processing:
Primary Ore Bin: 8’x12’ x 15’ steel hopper with steel grizzly and I-beam support (24 tons).
Fine Ore Feeder: 24-inch x 5-foot with 5 HP electric volume control.
Primary Jaw Crusher: 14” x 24” with 20 HP electric motor.
Ore Transportation and Handling:
Bucket Elevator: 6”x10” x 18’ with 2 HP electric motor.
Crushed Ore Bin: 8’ diameter, 15” tall, cone bottom, ¼” steel with I-beam legs.
Crushed Ore Feeder: Volume control, 2 HP, 15’ long, 18-inch rubber belt.
Milling and Grinding:
5’ x 6’ Denver Ball Mill: 50 HP electric motor, start panel, drum, mixed-size ball charge.
Rake Classifier: 4’ x 15’ with 5 HP electric motor.
Flotation Process:
Steel Tank: 5’ x 6’, ¼” steel, 2 HP agitator, steel prop, 3 HP.
4 Clarkson Reagent Feeders with Storage Side Tanks.
4 Denver #18 Sub A Flotation Cells with launders.
6 Denver #18 Sub A Flotation Cells.
Gravity Separation:
Wilfrey #12 Gravity Table: 2 HP gear head eccentric drive, 2 HR.
Pumps and Filtration:
Denver 1” Vertical Disc Pump: 1 HP electric.
3-Foot Disc Concentrate Filter De-water.
Heating and Furnace:
Propane Furnace: #300 carbide crucibles.
Facility Structures:
Mill Building: Warehouse/shop, steel beam frame, 40’x60’, sheet metal siding (no insulation).
Assay Office Structure:
Assay Office: 30’x40’, steel beam with sheet metal siding (no insulation).
Assay Equipment:
2”x4” Inch Jaw Crusher: 1 HP electric with sample tray.
Disc Grinder: 1 HP electric with sample tray.
Sample Scale with Test Weights.
Electric 12 Crucible Assay Furnace.
Steel Anvil (Lead Button) with Hammer.
Button Digest Crucibles Box (24).
Gold Balance with Test Weights and Pans.
Electric Vacuum Fan with Vent Hood/Discharge.
4ft x 6ft Double Deck Screen with 2 decks, feed apron, discharge apron.
4 Replacement Screens (80-150-200-250 mesh).
3’ diameter x 12-inch Discharge Fan: 2 HP electric.
Additional Facilities:
Chemical Shed: 15’x15’, sheet metal and wood construction.
Electrical CDWP Transformer.
Outside Safety Fence: Chain link, steel posts (3000 feet).
