Ivanhoe Mines’ Platreef Discovery and Mine Development, South Africa

Mine development work focused on resources in Flatreef underground discovery

The Flatreef Deposit, with a strike length of six kilometres, predominantly lies within a flat to gently dipping portion of the Platreef mineralized belt at relatively shallow depths of approximately 700 to 1,100 metres below surface.

The Flatreef Deposit is characterized by its very large vertical thicknesses of high-grade mineralization and the platinum-to-palladium ratio of approximately 1:1, which is significantly higher than other PGMs discoveries on the Northern Limb of the Bushveld. The grade shells used to constrain mineralization in the Flatreef Indicated Resource area have average true thicknesses of approximately 24 metres at a 2 g/t 2PE+Au (platinum-palladium-gold) cut-off grade.

On May 11, 2016, Ivanhoe Mines announced a substantial increase in Indicated and Inferred Mineral Resources at the Platreef Project. The updated estimate is for Mineral Resources amenable to underground mining methods within Platreef’s Flatreef Deposit. It is the first update of the overall resource estimate to be issued in more than three years. The new estimate includes the Turfspruit Cyclic Unit (TCU), which hosts the majority of the Flatreef Mineral Resources, and also two additional underground zones of mineralization – the Footwall (FW) and the Bikkuri (BIK) – that occur in close proximity to the TCU.

Indicated Mineral Resources now contain an estimated 42.0 million ounces of PGMs plus gold – a gain of 45% – with an additional 52.8 million ounces in Inferred Resources, at the base case cut-off grade of 2 grams/tonne. At a cut-off grade of 1 gram/tonne, Indicated Mineral Resources now contain an estimated 58.8 million ounces of PGMs plus gold, and an additional 94.3 million ounces in Inferred Resources.

The updated Mineral Resource estimate was prepared by Ivanhoe Mines under the direction of Dr. Harry Parker, RM SME of Amec Foster Wheeler E&C Services Inc (Amec Foster Wheeler). Dr. Parker and Mr. Timothy Kuhl RM SME, also of Amec Foster Wheeler, have independently confirmed the Mineral Resource estimate and are the Qualified Persons for the estimate, which has an effective date of April 22, 2016.

Click here to view Platreef Project - 2016 Resource Technical Report, June 2016

Platreef Mineral Resource - all mineralized zones (2.0 g/t base case).

Indicated Mineral Resources - Tonnage and Grades
Cut-off Grade (3PE+Au)MtPt (g/t)Pd (g/t)Au (g/t)Rh (g/t)3PE+Au (g/t)Cu (%)Ni (%)
3.0 g/t2042.112.110.340.
2.0 g/t3461.681.700.280.113.770.160.32
1.0 g/t7161.
Indicated Mineral Resources - Contained Metal
Cut-off Grade (3PE+Au)Pt (Moz)Pd (Moz)Au (Moz)Rh (Moz)3PE+Au (Moz)Cu (Mlbs)Ni (Mlbs)
3.0 g/t13.8613.862.230.9230.868001 597
2.0 g/t18.6618.943.121.2341.951 2262 438
1.0 g/t25.6326.814.491.8258.752 0764 108
Inferred Mineral Resources - Tonnage and Grades
Cut-off Grade (3PE+Au)MtPt (g/t)Pd (g/t)Au (g/t)Rh (g/t)3PE+Au (g/t)Cu (%)Ni (%)
3.0 g/t2251.911.930.320.
2.0 g/t5061.421.460.
1.0 g/t14310.880.940.
Inferred Mineral Resources - Contained Metal
Cut-off Grade (3PE+Au)Pt (Moz)Pd (Moz)Au (Moz)Rh (Moz)3PE+Au (Moz)Cu (Mlbs)Ni (Mlbs)
3.0 g/t13.7813.962.330.9431.018651, 736
2.0 g/t23.1723.784.261.5652.771,7753, 440
1.0 g/t40.3843.017.813.0694.274,1297,759
  1. Mineral Resources have an effective date of April 22, 2016. The Qualified Persons for the estimate are Dr. Harry Parker, RM SME, and Timothy Kuhl, RM SME, who are employees of Amec Foster Wheeler E&C Services Inc. and independent of Ivanhoe. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.
  2. The 2 g/t 3PE+Au cut-off is considered the base case estimate and is highlighted. The rows are not additive.
  3. Mineral Resources are reported on a 100% basis. Mineral Resources are stated from approximately -200 m to 650 m elevation (from 500 m to 1,350 m depth). Indicated Mineral Resources are drilled on approximately 100 x 100 m spacing (locally 150 m spacing); Inferred Mineral Resources are drilled on 400 x 400 m (locally to 400 x 200 m and 200 x 200 m) spacing.
  4. Mineral Resources have been estimated on an externally undiluted basis and without consideration for mining recovery. Dilution and mining recoveries will vary with the geometry (dip, thickness, faulting and or irregularities in contacts) of the mineralization and the eventual mining method used.
  5. Reasonable prospects for eventual economic extraction were determined using the following assumptions. Assumed commodity prices are Pt: $1,600/oz, Pd: $815/oz, Au: $1,300/oz, Rh: $1,500/oz, Cu: $3.00/lb and Ni: $8.90/lb. It has been assumed that payable metals would be 82% from a smelter/refinery and that mining costs (average $34.27/t) and process, G&A, and concentrate transport costs (average $15.83/t of mill feed for a 4 Mtpa operation) would be covered. The processing recoveries vary with block grade but typically would be 80%-90% for Pt, Pd and Rh; 70-90% for Au, 60-90% for Cu, and 65-75% for Ni.
  6. 3PE+Au = Pt + Pd + Rh + Au.
  7. Totals may not sum due to rounding.

Figure 1. Platreef’s Indicated Resources shown in green; Inferred Resources in blue; areas of resource expansion indicated with diagonal lines; exploration target areas in beige. Additional detail on the exploration target areas is shown in Figure 2.

Exploration targets provide upside in adjoining areas

Potential for additional UMT-TCU mineralization within targets for further exploration

Exploration potential exists immediately outside the area of Inferred Mineral Resources that has not been explored by Ivanhoe. Amec Foster Wheeler has defined four targets for further exploration (exploration targets) in areas that are contiguous with the current Mineral Resource areas that are shown in Figure 7.

Target 1 could contain 150 to 250 million tonnes grading 1.2 to 1.9 g/t Pt, 1.2 to 1.9 g/t Pd, 0.19 to 0.32 g/t Au, 0.08 to 0.14 g/t Rh, (2.6 to 4.3 g/t 3PE+Au), 0.11 to 0.19% Cu and 0.23 to 0.38% Ni over an area of 4.1 km2. The tonnage and grades are based on intersections of 2.0 g/t 3PE+Au mineralization in drill holes located adjacent to the target.

Target 2 could contain 50 to 90 million tonnes grading 1.3 to 2.1 g/t Pt, 1.4 to 2.3 g/t Pd, 0.19 to 0.31 g/t Au, 0.11 to 0.18 g/t Rh, (2.9 to 4.9 g/t 3PE+Au), 0.11 to 0.19% Cu and 0.23 to 0.39% Ni over an area of 3.9 km2. The tonnage and grades are based on intersections of 2.0 g/t 3PE+Au mineralization in drill holes located adjacent to the target.

Target 3 could contain 5 to 10 million tonnes grading 1.3 to 2.2 g/t Pt, 1.1 to 1.9 g/t Pd, 0.20 to 0.34 g/t Au, 0.10 to 0.17 g/t Rh, ( 2.7 to 4.6 g/t 3PE+Au), 0.11 to 0.18% Cu and 0.23 to 0.38% Ni over an area of 0.5 km2. The tonnage and grades are based on intersections of 2.0 g/t 3PE+Au mineralization in drill holes located adjacent to the target.

Target 4 could contain 40 to 60 million tonnes grading 1.3 to 2.2 g/t Pt, 1.5 to 2.5 g/t Pd, 0.18 to 0.30 g/t Au, 0.12 to 0.20 g/t Rh, (3.1 to 5.2 g/t 3PE+Au), 0.10 to 0.17% Cu and 0.22 to 0.36% Ni over an area of 1.5 km2. The tonnage and grades are based on intersections of 2.0 g/t 3PE+Au mineralization in drill holes located adjacent to the target.

The potential quantity and grade of these exploration targets is conceptual in nature. There has been insufficient exploration and/or study to define these exploration targets as Mineral Resources. It is uncertain if additional exploration will result in these exploration targets being delineated as a Mineral Resource.

In addition, there are approximately 48 km2 of unexplored ground beyond these exploration target areas on the property under which the prospective stratigraphy is projected to lie. It is not possible to estimate a range of tonnages and grades for this ground with current information. There is excellent potential for mineralization to significantly increase with further step-out drilling to the southwest.

Figure 2. Mineralization at the Platreef Project is open to expansion to the south and west, beyond the area of the current Mineral Resources. Indicated Resources are shown in green and Inferred Resources are shown in blue.

Development of Shafts #1 and #2

Following the successful commissioning and licencing of Shaft 1 in early July 2016, the permanent sinking phase has started. Ivanhoe expects that the subsequent main sinking phase will advance at a rate of approximately 45 metres per month until it reaches the planned, final depth at 1,025 metres below surface in 2018.

Included in the sinking contract is the development of four shaft stations at depths of 450 metres, 750 metres, 850 metres and 950 metres below surface. Shaft 1 is expected to reach the Flatreef Deposit at a depth of 777 metres below surface during early 2018.

Shaft 1 will provide early development access into the deposit and will be utilized to fast track the production during the first phase of the project.

The selected mining areas proposed in the current Platreef Project pre-feasibility study mine plan occur at depths ranging from approximately 700 metres to 1,200 metres below the surface. Four vertical shafts are expected to provide the main access to the Flatreef Deposit and ventilation. Shaft 2 will host the main personnel transport cage, material and ore-handling systems, while Shafts 1, 3 and 4 are planned to be utilized for ventilation to the underground workings. Shaft 1, now under development, will be used for initial access to the deposit and early underground development.

The planned mining methods will use highly productive, mechanized methods, including long-hole stoping, drift-and-bench and drift-and-fill mining methods. The mined-out areas within the deposit will be backfilled with a paste mixture that utilizes tailings from the process plant and cement. The ore will be hauled from the stopes to a series of ore passes that will connect to a main haulage level connected to Shaft 2, where it will be hoisted to the surface for processing.

Shaft 2 will have an internal diameter of 10 metres and will have the capacity to hoist six million tonnes per year. The headgear design for the six-million-tonne-per-year permanent hoisting facility has been completed by South Africa-based Murray & Roberts Cementation. Ivanhoe expects to start Shaft 2 early works, including civil work for the box-cut and hitch-foundation, in 2017.

Ivanhoe Mines’ exploration geologists receive the 2016 Colin Spence Award for excellence in global mineral exploration for the Flatreef Discovery of platinum-group metals in South Africa