Jiama Phase 2 Expansion Project — 2014 Technical Report

This technical report presents the processing facilities and expansion plans at the Jiama copper-molybdenum operation as of January 2014.

Report context

The Jiama Phase 2 Expansion Project 2014 Technical Report, dated January 2014, describes the existing processing plants at the Jiama operation, together with design parameters for the planned Huatailong No. 2 New Mineral Processing Plant. The report covers the Huatailong No. 1 Plant, a 600 tpd Pilot Plant, and the proposed 43,500 tpd expansion plant. The existing Huatailong No. 1 Plant commenced operation in 2010 and currently treats copper-molybdenum ore from the Tongquianshan and Niumatang open cut mines.

Processing route

Huatailong No. 1 Plant

The existing 6,500 tpd Huatailong processing plant was designed to treat both Copper-Molybdenum and Copper-Molybdenum-Lead-Zinc ores. For treatment of copper-molybdenum ores, the flotation cells installed to separate lead from copper concentrates are not in operation. If the molybdenum content is too low to be economic, the copper-molybdenum separation flotation circuit is shutdown. Currently, copper concentrate containing gold and silver credits is produced through a conventional beneficiation circuit.

Run-of-Mine is reduced in three stages of crushing, then delivered to a fine ore storage bin. The bin discharges to parallel Primary Ball Grinding Mills operating in closed circuit with hydro-cyclone classifiers. The grinding circuit product at p70 of 74 microns reports to a bulk flotation rougher-scavenger circuit, followed by three cleaning stages. The rougher-scavenger tailings feed a zinc flotation circuit to produce a zinc concentrate and final tailings, which are dewatered in a press filter press and stockpiled.

The copper-molybdenum-lead concentrate is refloated to separate the lead. The copper-molybdenum tail is reground in a ball mill closed with hydrocyclones, then refloated to separate molybdenum from the copper. In Column Cells, all concentrates are thickened and filtered in ceramic disc filters and delivered to stockpiles.

The fine regrind in the copper molybdenum circuit, coupled with the high altitude location, results in high moisture content (approximately 13%) in the copper concentrate through the ceramic disc filter. A filter press with air blow facility would be necessary to improve this.

Pilot Plant

The process plant rated at 600 tpd was constructed using equipment from an earlier processing plant and used for pilot plant testwork. This plant was modified in 2011. The copper-lead-zinc ore represents approximately 3% of the total ore resource and requires a different processing route to produce saleable copper, lead and zinc concentrates.

The flowchart comprises conventional three stage crushing, primary ball mill grinding delivered to flotation circuits for sequential copper, lead and zinc separation. The parallel ball mills are closed with spiral classifiers; the overflow reports to flotation and the sands return to the mill. The flotation feed size is p70 of 74 microns. Copper, lead and zinc concentrates are thickened and then dewatered in ceramic disc filters.

Huatailong No. 2 New Mineral Processing Plant (Proposed Design)

The 43,500 tpd nameplate capacity plant will treat skarn and hornfels hosted copper-molybdenum ores. The design provides for separate or blended treatment. The process flowchart was developed from the results of testwork carried out by the General Research Institute Beijing, and operational experience with the current plant.

The front end comminution will comprise a Primary Gyratory crusher to prepare feed for parallel SAG Mill-Ball Mill circuits. The SAG Mills circuit will incorporate cone crushers to reduce any critical size pebbles. The Primary Ball mills are closed with Hydrocyclones and produce a grind size of p70 = 74 microns for bulk copper-molybdenum flotation.

The two ore types (skarn and hornfels) have different characteristics in terms of mineral assemblage, head grades, and hardness. The parallel circuits will provide flexibility for separate or blended treatment, and flexibility in maintenance scheduling.

The flotation circuitry and reagent regime is conventional, comprising bulk flotation and cleaning of the copper and molybdenum, regrinding of the cleaner concentrate to p90 = 45 microns, followed by selective flotation of the molybdenum from the copper using column flotation cells to achieve the best molybdenum concentrate grades and recovery.

The copper concentrate will be thickened and filtered in a ceramic disc; the molybdenum concentrate will be dewatered in a pressure filter and dried in a rotary dryer. Flotation tailings will be dewatered in filter presses and delivered to a tailing storage facility.

Key reported parameters

Technical qualifications

This technical report is dated January 2014. The Huatailong No. 2 New Mineral Processing Plant was at the time over 50% complete, supported by the "Jiama Phase 2 Preliminary Design Capital Cost Report" dated November 2013. The report presents design criteria for skarn and hornfels copper-molybdenum ores based on testwork at the General Research Institute Beijing, and design criteria for skarn copper-lead-zinc ore based on pilot plant testwork. Capital and operating cost estimates were prepared using standard project engineering methodology, with major equipment quotes obtained from vendors. The report notes that the copper-molybdenum and copper-lead-zinc circuits are not operating for the current ore feed at the Huatailong No. 1 Plant, as the molybdenum content is too low to be economic.

Source: Jiama Phase 2 Expansion Project , 2014 Technical Report, Section 17 Recovery Methods, dated January 2014.