Mining Intelligence and News
United States

Henderson Mine

Click for more information

Categories

Overview

Mine TypeUnderground
StatusActive
Commodities
  • Molybdenum
Mining Method
  • Block caving
Production Start1976
Mine Life2038
SnapshotHenderson mine is the largest primary producer of molybdenum in the world.

Separated by the Continental Divide, the Henderson Mine and Mill are connected by one of the world’s longest conveyor systems, a 10 mile elevated belt that runs underneath the Continental Divide and emerges above ground for the final five miles.

Owners

SourceSource
CompanyInterestOwnership
Freeport-McMoRan Inc. 100 % Indirect
Climax Molybdenum Company (operator) 100 % Direct
Freeport-McMoRan owns 100% of Henderson mine through its wholly-owned subsidiary Climax Molybdenum Company.

Contractors

ContractorContractDescriptionRef. DateSource
Xcel Energy Inc. Power supply Henderson operations receive electrical power through long-term contracts with Xcel Energy. Dec 31, 2023

Deposit type

  • Porphyry

Summary:

The Henderson mine is a porphyry molybdenum deposit with molybdenite as the primary sulfide mineral.

The Henderson deposit is composed of two partially overlapping ore bodies beneath the summit of Red Mountain. The ore bodies are entirely within a Tertiary rhyolite porphyry intrusive complex that has intruded the Precambrian Silver Plume granite. The mineralization is relatively continuous in the ore bodies and consists of molybdenite and quartz in random intersecting closely spaced veinlets.

Reserves at December 31, 2023

Cut-off grade for Mineral reserves is 0.13% Mo.

Cut-off grade for Mineral resources is 0.11% Mo.
CategoryTonnage CommodityGradeContained MetalRecoverable Metal
Proven 34 Mt Molybdenum 0.18 %
Probable 14 Mt Molybdenum 0.12 %
Proven & Probable 48 Mt Molybdenum 0.16 % B lbs 0.15 B lbs
Measured 72 Mt Molybdenum 0.15 %
Indicated 32 Mt Molybdenum 0.12 %
Measured & Indicated 104 Mt Molybdenum 0.14 % 0.33 B lbs

Mining Methods

  • Block caving

Summary:

The Henderson operation consists of a large block-cave underground mining complex feeding a concentrator with a current capacity of approximately 32,000 metric tons per day.

The available underground mining equipment fleet consists of fifteen 9-metric-ton load-haul-dump (LHD) units and seven 73-metric-ton haul trucks, which deliver ore to a gyratory crusher feeding a series of 3 overland conveyors to the mill stockpiles.

The Henderson mine is located in a mountainous region with the main access shaft at 3,180 meters above sea level. The main production levels are currently at elevations of 2,200 and 2,350 meters above sea level.

The Henderson mine and mill are connected by a 10-mile conveyor tunnel under the Continental Divide and an additional five-mile surface conveyor.

Comminution

Crushers and Mills

TypeModelSizePowerQuantity
Gyratory crusher 1

Summary:

The available underground mining equipment fleet delivers ore to a gyratory crusher feeding a series of three overland conveyors to the mill stockpiles.

Processing

  • Vacuum filtration
  • Crush & Screen plant
  • Flotation
  • Dewatering
  • Roasting

Summary:

Henderson has the capacity to produce approximately 15 million pounds of molybdenum per year. The majority of the molybdenum concentrate produced is shipped to our Fort Madison, Iowa, processing facility.

The mine and the Mill are connected by a fifteen-mile elevated belt that passes underneath the Continental Divide through an old train tunnel and then above ground to the mill. Molybdenite (the molybdenum containing mineral) is obtained from the ore by crushing, grinding, and flotation.

Flotation & Concentration
Chemicals are added to the slurry. These are called collectors and frothers. The collectors attach to the surface of the molybenite causing it to become hydrophobic or “water hating.” The slurry is poured into giant mixing tanks called flotation cells. Air is introduced to the mixing process to create air bubbles. The hydrophobic moly sticks to the air bubbles and floats to the surface of the tank where they are skimmed off. The frother that was added earlier makes sure that the bubbles are stable and don’t burst before the moly can be skimmed off.

The final concentrate, still in the form of a slurry, is processed through many filters where the water is removed. A vacuum pulls the water away and a “cake” of molybdenite is left behind. These cakes go through a heat drying process to make sure any remaining water is removed. A dry, concentrated gray-black powder remains. The powder is packaged into giant bags that weigh about 3,750 pounds when they are full. The bags are shipped to a “roasting” plant for further processing.

The waste or tailings from the milling process is still in the form of slurry. It flows down into an area where the particles settle out of the water and create a tailings dam. The water is returned to the mill and is recycled over and over again.

Roasting
The roasters are huge – tall as a six-story building and 21 feet in diameter. They run twenty-four hours a day at a temperature of approximately 1200 degrees Fahrenheit. At the roasting plant, about 120,000 pounds of molybdenum concentrate are processed daily.

Even though the moly can be 98% pure when it leaves the mill, it needs to be purified even more so it can be used in hundreds of products. The heat of the roasting process removes all remaining impurities.

Production

CommodityUnits202320222021202020192018201720162015
Molybdenum M lbs 131212101214121025
All production numbers are expressed as metal in concentrate.

Operational metrics

Metrics202320222021202020192018201720162015
Daily milling capacity 32,000 t32,000 t32,000 t32,000 t32,000 t32,000 t32,000 t32,000 t32,000 t
Annual production capacity 15 M lbs of molybdenum metal in concentrate15 M lbs of molybdenum metal in concentrate15 M lbs of molybdenum metal in concentrate16 M lbs of molybdenum metal in concentrate18 M lbs of molybdenum metal in concentrate18 M lbs of molybdenum metal in concentrate35 M lbs of molybdenum metal in concentrate35 M lbs of molybdenum metal in concentrate40 M lbs of molybdenum metal in concentrate

Production Costs

Commodity production costs have not been reported.

Heavy Mobile Equipment

HME TypeSizeQuantity
Load-Haul-Dump (LHD) 9 t 15
Truck (underground) 73 t 7

Personnel

Mine Management

Job TitleNameProfileRef. Date
Chief Geologist Nyssa Loeppke LinkedIn Feb 23, 2024
Mine Manager Dave Loring LinkedIn Feb 23, 2024
Mine Production Superintendent Josh Gresham LinkedIn Feb 23, 2024
Sr. Mine Engineer Dino Febiawan LinkedIn Feb 23, 2024
Supply Chain Superintendent Catherine Patti LinkedIn Feb 23, 2024

Total WorkforceYear
358 2023
360 2022
360 2021
383 2020

Aerial view: