| Company | Pebble Limited Partnership |
| Date | 2022 |
| Region | Alaska, USA |
| Commodities | Copper, Gold, Molybdenum |
| Mine Type | Open Pit |
| Throughput | 180,000 tpd |
| Mine Life | 20 years |
| Status | Development |
Executive Summary
This NI 43-101 Technical Report outlines the recovery methods for the Pebble Project, a large-scale copper-gold-molybdenum deposit. The processing plant is designed with a feed rate of 180,000 tons per day, utilizing a SABC (SAG mill, Ball mill, Pebble crusher) circuit for comminution. The ore is processed to produce two principal products: a copper-gold flotation concentrate and a molybdenum flotation concentrate, along with a tertiary gravity gold concentrate.
The flowsheet includes primary crushing via gyratory crushers, followed by grinding in SAG and ball mills. Bulk copper-gold-molybdenum flotation is performed using tank cells, with subsequent regrinding and gravity concentration to recover gold. Molybdenum is separated from the bulk concentrate through selective flotation using column cells and HIG mills. The final concentrates are dewatered and filtered for shipment, with tailings managed in separate TSFs.
The process design criteria indicate a Life of Mine (LOM) of 20 years with a daily process rate of 180,000 tons. The ore is sulphide-based, requiring specific reagents such as sodium hydrosulphide for copper sulphide depression during molybdenum flotation. Power is supplied by a natural gas-fired combined cycle plant, and fresh water is sourced from a treatment plant for various applications including reagent preparation and cooling.
Website: https://northerndynastyminerals.com/pebble-project/project-overview/
Report Date: 2022
Region: Alaska, USA
Project Status: Development
Commodity: Copper, Gold, Molybdenum
Throughput: 180,000 tpd
Mine Life: 20 years
Mine Type: Open Pit
Consolidated report summaries
The following former standalone pages about this operation were consolidated here in October 2026. They are retained for source traceability; dates and figures reflect each report’s own effective date and may be superseded by the current information above.
NI 43-101 Technical Report Update and Preliminary Economic Assessment — Pebble Project
NI 43-101 Technical Report Update and Preliminary Economic Assessment — Pebble Project
| Company | Pebble Limited |
| Date | 2023 |
| Region | Alaska, USA |
| Commodities | Copper, Gold, Molybdenum |
| Mine Type | Open Pit |
| Throughput | 180,000 tpd |
| Mine Life | 20 years |
| Status | Development |
Executive Summary
The Pebble Project Technical Report Update and Preliminary Economic Assessment (August 2023) outlines a comprehensive recovery method for a large-scale porphyry deposit. The processing plant is designed for a daily throughput of 180,000 tons, utilizing a SABC (SAG mill, Ball mill, Pebble crusher) circuit to grind ore to a P80 of 135 µm. The metallurgical flow sheet focuses on the recovery of copper, gold, and molybdenum through a combination of bulk flotation, selective molybdenum flotation, and gravity concentration.
The process begins with primary gyratory crushing followed by SAG and ball milling. Bulk rougher flotation collects copper, gold, and molybdenum, which is then reground. A portion of the regrind underflow is treated with centrifugal gravity concentrators to recover free gold. The bulk concentrate undergoes three stages of cleaner flotation before molybdenum is separated from the copper-gold concentrate using selective flotation with sodium hydrosulphide depression and four stages of column cleaning. Final concentrates are thickened, filtered, and dried (for molybdenum) for shipment.
The design supports a 20-year mine life with specific concentrate grades targeting 26% Cu, 16 g/t Au, and 50% Mo. The facility includes extensive reagent handling, tailings management with separate bulk and pyritic streams, and a marine terminal for concentrate transport via Lake Illamina.
Website: https://northerndynastyminerals.com/pebble-project/project-overview/
Report Date: 2023
Region: Alaska, USA
Project Status: Development
Commodity: Copper, Gold, Molybdenum
Throughput: 180,000 tpd
Mine Life: 20 years
Mine Type: Open Pit
Ore type:
Pebble Project — 2021 Preliminary Economic Assessment
Pebble Project — 2021 Preliminary Economic Assessment
| Company | Pebble Limited Partnership |
| Date | 2021-09-09 |
| Region | Alaska, USA |
| Commodities | Copper, Gold, Molybdenum |
Executive Summary
The Pebble Project 2021 Preliminary Economic Assessment outlines a comprehensive recovery method designed to process 180,000 tons per day of run-of-mine material. The plant is configured to produce three principal products: a copper-gold flotation concentrate, a molybdenum flotation concentrate, and a tertiary gravity gold concentrate. The process flow begins with primary crushing using two gyratory crushers, followed by a SABC circuit involving SAG mills, ball mills, and pebble crushers to achieve a grind size of 135 µm P80.
Bulk flotation is employed to recover copper, gold, and molybdenum together, utilizing tank cells for rougher and scavenger stages. The bulk concentrate undergoes regrinding to 25 µm P80, with a portion diverted to centrifugal gravity concentrators for gold recovery. Subsequent cleaner flotation stages upgrade the bulk concentrate before molybdenum separation. The molybdenum circuit uses column cells for cleaning and nitrogen atmosphere to depress copper sulphides. Final concentrates are dewatered via filtration and drying, with copper-gold concentrate shipped via pipeline to a marine terminal and molybdenum concentrate bagged and containerized at the mine site.
The design criteria specify a 20-year life of mine with a feed grade of 0.46% Copper, 0.47 g/t Gold, and 0.03% Molybdenum. The processing plant operates 365 days per year with high availability targets for grinding and flotation circuits (92%). Tailings are managed in separate bulk and pyritic facilities, and process water is recycled extensively. Power is supplied by a natural gas-fired combined cycle plant, ensuring energy efficiency for the large-scale operation.
Website: https://northerndynastyminerals.com/pebble-project/project-overview/
Report Date: 2021-09-09
Region: Alaska, USA
Project Status:
Commodity: Copper, Gold, Molybdenum
Throughput:
Mine Life:
Mine Type:
Ore type:
