The processing plant at the Lordsburg millsite produced smelter flux and flotation concentrate from Summit Mine material during operations from March 2010 to October 2013.
Report context
The processing plant operated from March 2010 to October 2013, producing two separate products for sale to local and overseas smelters. The Lordsburg millsite is situated 4.8 miles southwest of the town of Lordsburg at the site of the former Banner Mining Company and Federal Resources Bonney copper mine and mill. Lordsburg Mining purchased the grinding and flotation section of the 400-ton-per-day St. Cloud Mining Company mill located at Winston, New Mexico. The equipment was dismantled and moved to the old Banner millsite where it was refurbished. A new building was purchased, concrete poured, and the mill reconstructed. A two-stage portable crushing plant located at the nearby St. Cloud aggregate quarry was purchased, refurbished, and moved to the new millsite. A shop and analytical laboratory were built. The former Banner mine-manager’s house was repaired and made into the project office. A lined, stormwater-catchment pond was constructed adjacent to the millsite. A lined, tailings-impoundment facility was constructed in the original Banner tailings basin.
Processing route
Crushing and Screening
Production from the Summit Mine is received in 24-ton-capacity, highway haul trucks. The material is dumped and pushed into stockpiles with a front-end loader. Mine-run material is fed by front-end loader into a portable, two-stage, Cedar Rapids crushing-screening plant. A nominal minus 3/8-inch product is stockpiled by a stacker conveyor over a mill feed reclaim tunnel. Storage capacity is about 4000 tons. The crushing plant has a 25 x 40-inch jaw crusher and a 45-inch cone crusher operating in a closed-circuit system.
Processing involves crushing run of mine material through a jaw and cone crusher in closed circuit with a triple-deck screen. The ball mill feed material is crushed to minus 1/4 inch while the smelter flux is sized to minus 3/8 and plus 1/4 inch. Fines remaining from crushing of flux are added to the mill feed stockpile. A portion of the minus 3/8 inch is screened to 3/8 inch x 1/4 inch and stockpiled separately in the mill yard for shipment as flux. The crushing plant can process 50 tons per hour and will operate one shift per day, 5 days per week.
Grinding and Flotation
Vibrating feeders in the mill feed reclaim tunnel place the fine crushed material onto a conveyor for transport to a 7-ft x 10-ft, 300 H.P., rubber-lined ball mill where the feed is ground to a nominal 80% passing 100 mesh. The ball mill discharge goes to a conditioner tank and then to banks of Denver flotation cells including roughers, scavengers and cleaners. The flotation concentrate is pumped to a 24-ft x 10 ft-diameter, concentrate thickener for storage and thickening.
The minus 1/4 inch crusher fines are fed through a ball mill for grinding to 80% minus 100 mesh and fed through a rougher, scavenger and cleaner flotation circuit. The cleaner concentrate is dewatered in a thickener and drum filter and air dried to 8% moisture for shipment. Concentrate is loaded into one ton super sacks and loaded into a sea container for shipment to overseas smelter in 20-ton lots. Smelter flux is loaded onto highway trucks for delivery to the smelters. Tailings from the process flows by gravity into a lined tailings storage facility.
The principal reagents used in the flotation process are: potassium amyl xanthate (KAX) – collector/promoter at 0.05 lb/ton; dithiolphosphate (Aero 3477) – promoter at 0.067 lb/ton; frother (Flomin F-160) – flotation reagent at 0.052 lb/ton; and soda ash – pH control, used periodically. The milling section can process 240 tons per day and will operate 7 days per week.
Historical Operating Data
Operations to date have shipped 69,765 tons of flux to smelters containing 360,000 ounces of silver and 5580 ounces of gold and processed an additional 110,315 tons of material in the grinding and flotation plant to produce 446 tons of concentrate containing 340,526 ounces of silver and 6,819 ounces of gold. Flux shipments were made to both Freeport McMoRan (FMI) at the Miami smelter operation and to Asarco at the Hayden smelter operation, both in Arizona. Both smelters have expressed interest in continuing flux shipments once operations resume.
Key reported parameters
| Parameter | Value | Basis |
|---|---|---|
| Crushing plant capacity | 50 tons per hour | Design |
| Crushing plant operating schedule | One shift per day, 5 days per week | Design |
| Mill feed stockpile capacity | About 4000 tons | Design |
| Ball mill dimensions | 7-ft x 10-ft, 300 H.P., rubber-lined | Design |
| Ball mill grind size | 80% passing 100 mesh (nominal) | Design |
| Milling section capacity | 240 tons per day | Design |
| Milling section operating schedule | 7 days per week | Design |
| Concentrate thickener dimensions | 24-ft x 10 ft-diameter | Design |
| Concentrate moisture after drying | 8% | Design |
| KAX reagent dosage | 0.05 lb/ton | Design |
| Aero 3477 reagent dosage | 0.067 lb/ton | Design |
| Flomin F-160 reagent dosage | 0.052 lb/ton | Design |
| Flux shipped (historical) | 69,765 tons | Actual |
| Silver in flux shipments | 360,000 ounces | Actual |
| Gold in flux shipments | 5580 ounces | Actual |
| Material processed in flotation plant (historical) | 110,315 tons | Actual |
| Concentrate produced (historical) | 446 tons | Actual |
| Silver in concentrate (historical) | 340,526 ounces | Actual |
| Gold in concentrate (historical) | 6,819 ounces | Actual |
| Flux product size | Minus 3/8 inch, plus 1/4 inch | Design |
| Mill feed size | Minus 1/4 inch | Design |
Technical qualifications
The recovery methods described represent the processing plant design as originally implemented and the historical operating data from March 2010 to October 2013. The report references simplified and detailed flow sheet diagrams (Figures 17.1 and 17.2) that are not reproduced in this text. No testwork results, economic analysis, or feasibility assessments are included in the recovery methods section of the report. The crushing plant and milling section capacities and operating schedules are stated as design parameters, not necessarily as achieved during operations. The report does not provide metallurgical balances, recovery percentages, or grade data beyond the contained ounces reported in shipments.
Source: Lordsburg Mining , Summit Mine, Technical Report, Section 17.0 Recovery Methods, 17.1 Introduction, 17.2 Lordsburg Millsite – General, 17.3 Crushing and Screening, 17.4 Grinding and Flotation.
