Overview

Deposit type

• Sediment-hosted
• Breccia pipe / Stockwork

Summary:

The Mutanda mineralisation is a typical DRC copper belt metasedimentary copper and cobalt deposit. The mineralisation generally occurs as infilling of fissures and open fractures associated with brecciation.

The Mutanda copper-cobalt deposit lies with the lower part of the Neoproterozoic Katangan sedimentary succession which extends over more than 700 km from Zambia through the Katanga province of the DRC and is up to 150km wide. It is part of a thrust-and-fold belt known as the Lufilian Arc. It shares the same characteristics of most of the deposits within the Copperbelt in that it is stratiform and associated with carbonate or carbon-rich lithologies (Cailteux, et. al. 2005).

The main copper oxide minerals present are malachite and pseudomalachite, with heterogenite, the main Cobalt mineral. Quartz and chlorite dominate the gangue component in all the samples.

The sulphide minerals have yet to be subjected to a laboratory mineralogical analysis.

Four mineralised bodies have been delineated at Mutanda. The largest of these lies in the East Zone which extends along an east-west strike for 900m and down dip for 500m. It lies within the R4 dolomites and dolomitic shales and is up to 50m thick near surface. This body dips at 35° to the south and plunges towards to southeast. Although sulphides have been intersected at depth these are more sparsely drilled and have yet to be investigated in detail. The down-plunge extensions of this mineralisation have yet to be drilled.

A second carbonaceous shale-hosted mineralised zone lies stratigraphically above the main mineralisation (some 60m vertically below) and has been intersected in only seven drillholes. It appears to be variable in thickness and intensity of the mineralisation but visually the grades for both copper and cobalt appear to be higher than those in the carbonate hosted sulphide zone.

Mining Methods

• Truck & Shovel / Loader

Summary:

The mining method applied is conventional open pit mining, consisting of drilling, blasting, loading and hauling.

All future mining is planned based on contractor mining.

Pit designs were created based on the current mining methodology that includes mining at 5m or 10m benches. Ramp and pit access designs considered the largest envisaged hauler dimension specifications ensuring safe and practical execution. Pit designs were conducted based on the optimum pit shell. All pit designs adhere to current geotechnical requirements.

Comminution

Crushers and Mills

Summary:

The ROM ore will be tipped into a ROM tip bin equipped with a static grizzly which will ensure that oversize material will not report to the primary crusher (oversize material can choke the crusher). Ore will be withdrawn from the ROM tip bin using a variable speed apron feeder to a vibrating grizzly feeder (to scalp off fines) ahead of the primary crusher. A single toggle jaw crusher will be sized for the purpose of primary crushing.

Ore from the primary crusher will be scrubbed ahead of secondary and tertiary crushing to remove clay associated with the ore. The scrubber will be equipped with a trommel screen and oversize material from this screen will be crushed using an open circuit secondary impact crusher while trommel undersize will be wet screened on a double deck screen. Oversize from this screen will be crushed using a tertiary impact crusher, intermediate product will be conveyed to the mill feed bin and the undersize slurry pumped to the mill discharge sump. Both products from secondary and tertiary crushers will be screened on a single deck screen, with the oversize recycled to the tertiary crusher for further size reduction and the undersize reporting to the mill feed bin. A feed bin will be installed ahead of each impact crusher to ensure consistent feed to the crushers.

Milling and classification of the crushed ore will be through an overflow discharge wet ball mill operating in closed circuit with a hydrocyclone cluster. Crushed ore will be fed to the ball mill using a variable speed belt feeder and mill feed conveyor. The primary screen undersize will be pumped to the mill discharge sump to join the ball mill discharge. The mill discharge together with the primary screen undersize will be pumped to a hydrocyclone cluster. The overflow from the hydrocyclone cluster will be the circuit product and will gravitate to pre leach thickening while the underflow from the hydrocyclone cluster will gravitate to the ball mill for further size reduction.

Processing

• Sulfuric acid (reagent)
• Crush & Screen plant
• Spiral concentrator / separator
• Acid plant
• Counter current decantation (CCD)
• Agitated tank (VAT) leaching
• Dense media separation
• Dewatering
• Filter press
• Solvent Extraction & Electrowinning

Summary:

The concentrate operations consist of a crusher, a small dense media separator plant, and a spiral plant. These operations produce more than 20,000 metric tons each year. The two older Mutanda copper plants consist of four tank houses, commissioned between September of 2010 and January 2012. They use two-stage metallurgical process of solvent extraction and electro winning to process a combined 110,000 metric tons of copper each year. The expansion completed at the end of 2013 included the addition of:
· Increasing crushing, milling, leaching and CCD capacity to 200 ktpa (kilo-tonnes per annum) at design feed grades.
· 54 ktpa HG SX and 46 ktpa LG SX.
· Adding Electro winning sections EW5 to EW7 of 30 ktpa each.

The sulfuric acid and liquid sulfur dioxide plant was commissioned in early 2012 and has an expected daily capacity of 390 MT of sulfuric acid and 73 MT of liquid sulfur dioxide. The production of sulfur dioxide – a reagent used in cobalt leaching, enables significant savings in reagent costs.

Leaching, using acidified raffinate and/or sulphuric acid, will take place in four mechanically agitated tanks operating in a series overflow cascade configuration under atmospheric conditions. A 25% W/w Sodium Metabisulphite solution will be also added to the leach tanks to facilitate the leaching of the Co3+ species by reducing the Co3+ to Co2+.

The slurry from the final leach tank will be washed, with cobalt effluent solution topped up with return dam solution, and then thickened in a series of five counter current decantation CCD thickeners. Alternate wash water will be sourced in order of preference from process water, raw water or raffinate.

The overflow from the first CCD thickener will be treated in a clarifier to reduce the amount of suspended solids in the pregnant leach solution (“PLS”). Overflow from the clarifier will gravitate to the PLS pond while the underflow from the final CCD thickener will be pumped to the tailings disposal tank. The clarifier underflow will be pumped back to the CCD circuit or the clarifier feed tank. Due to the need to further dilute the discharge from the final leach tank in the CCD thickeners before thickening to ensure optimum settling of solids, high rate thickeners with auto feed dilution will be incorporated into the design.

The PLS (aqueous phase) will be pumped to two extraction mixer settlers where it will be mixed with an organic solvent solution consisting of an extractant and diluent (organic phase). The solvent solution will extract the copper from the PLS producing a copper loaded organic stream (loaded organic) and a copper depleted aqueous stream (raffinate).

The loaded organic will be mixed with a solution from electrowinning (spent electrolyte) in two stripping mixer settlers where it will be stripped of the copper producing an advance electrolyte. This advance electrolyte will be filtered using dual media filters to remove entrained organic solution, to prevent ‘organic burn’ on the deposited copper. The advance electrolyte will then be heated using a heat exchanger prior to it being fed to electrowinning. The stripped solvent solution (stripped organic) will be returned to the extraction mixer settlers.

Advance electrolyte will be pumped to 16 polishing cells before being pumped to 66 commercial cells. Each cell will have 48 cathodes and 49 anodes. Copper will plate onto the cathodes by the process of electroplating. Blank stainless steel cathodes and lead anodes will be used in the cells. The spent electrolyte from the electrowinning banks will be pumped back to the strip section of solvent extraction. After the plating cycle, the cathodes will be removed from the electrowinning cells, washed in a hot water tank, the deposited copper stripped from the cathodes using a semi automatic stripping machine and the blank cathodes returned to the cells. The copper stripped from the cathodes will be the finished copper product.

Production

Personnel

Job Title	Name	Profile	Ref. Date
Engineering Manager	Aubrey Thiel		May 2, 2024
Health, Safety & Environment Manager	Roger Dancause		May 2, 2024
Maintenance & Reliability Manager	Augustin Mukini		May 2, 2024
Process Plant Superintendent	Gourab Satapathy		May 2, 2024
Procurement Superintendent	Declain Muland		May 2, 2024
Sr. Plant Manager	Mark Badyoczek		May 2, 2024