Henderson Mine is an underground molybdenum mine located near Empire, Colorado that is owned and operated by the Climax Molybdenum Company, a subsidiary of Freeport McMoRan (one of the world’s largest base metal producers). Their mining method consists of underground block-caving where molybdenite ore is extracted. The Henderson Mine has been operating since 1976 and most of the ore they extract is processed into concentrate and shipped to a processing facility in Fort Madison, Iowa where it is made into a number of different products made available for final sale to customers.
Henderson Mine is a 30,000 tons per day (tpd) underground operation running approximately 11,000 truck cycles per month. With a measured average of 3 tons of deadbed per truck, Henderson would be able to gain an extra 33,000 tons per month by simply using Alderox® ASA-12® to eliminate deadbed and running the same amount of truck cycles.
Following a successful demonstration with a handheld sprayer with 120 psi, Henderson worked together with the manufacturer to build an automated applicator system and to run a 60 day trial to determine correct operating logistics.
The applicator system development was designed and built over three months. Various working models were tested but the final configuration included the following specifications:
- Heavy duty steel construction powder coated for durability >
- Dual 150 psi diaphragm pumps >
- 1500 lb electromechanical ram >
- Able to be operated on any 110 volt power source >
- Multiple spray nozzles to provide coverage to entire truck bed >
- Safety sensors to ensure proper placement of spray head in truck bed >
- Preprogrammed on-board computer system >
- Activated remotely by truck drivers from the cabs of their trucks >
- Able to select heavy or regular amounts of spray depending on the material being hauled >
- Spray head is designed to slide out of truck bed in case of malfunctions or power loss. >
To eliminate the capital expenditure portion of the project, the automated applicator system (Figure 1) is supplied to Henderson at no charge by the manufacturer for as long as Henderson continues purchasing product.
The location of the sprayer was easy to determine since all operating trucks dump out at the crusher. The automated applicator system has the option of being trailer-mounted but Henderson decided on permanently installing it adjacent to the crushing station. To use the product, truck operators simply line up to a red laser beam and to activate the system, they press a button similar to a garage-door opener. The applicator will then lower into the truck bed and evenly mist Alderox® onto the metal liners. The applicator ensures that the correct amount of product is always applied, thereby eliminating overuse and allowing maximum performance of Alderox® ASA-12®.
The product requires no mixing/dilution and with every new container, the pump and lines only need to be primed before regular operation. The entire application process takes no longer than two minutes which include lining up to the spray system and actual spraying time.
With one gallon of Alderox® covering approximately 1,000 square feet, only a very small amount is required per application. Henderson uses one half gallon per truck per spray and sprays approximately once every 25 truck cycles. In general, the applicator frequency and amount will vary throughout the year due to climate and precipitation pattern changes but since Henderson is an underground operation, they remain at a steady application frequency year round.
Outside of environmental and safety concerns, another main concern included possible negative effects of Alderox® on equipment, material, or downstream processing. To date, there have been no recorded negative effects on equipment and material. In regards to downstream processing, after review of the product ingredients and the quantity used per day, the chief engineer at Henderson’s processing plant stated that there are no anticipated recovery or grade effects on the processing circuit. To date, there are no reports of a dramatic change in concentrate grade or recovery that has been attributed to using Alderox®.
Henderson Mine completed the 60 day trial process in mid-June of 2007. The trial was successful and Henderson continues to implement the Alderox® procedure in their regular operations.
