The Hinda Project is one of the World’s largest undeveloped phosphate projects, with the Mineral Resource based on continuous mineralization over 20km of strike. At an average thickness of 60m, the ore body is also the thickest sedimentary phosphate deposit known. Cominco discovered and evaluated the deposit with an intense work programme including a drilling campaign of 929 holes.
The exploration and drilling database is independently maintained and verified by CSA Global. The July 2013 JORC 2012 & NI 43-101 Mineral Resource Estimate totals 675.8t Measured, Indicated and Inferred. Following completion of the Definitive Feasibility Study, SRK (UK) provided a JORC compliant Ore Reserve of 404.9Mt grading 11% P2O5.
The Hinda Life of Mine plan developed by SRK schedules mining of a total of 1,489.7 Mt of material, comprising 1,084.7 Mt of overburden and 405.0 Mt of Ore. Mining operations will commence in the southern portion of the Orebody, progressing northwards at an average rate of approximately 500 m per annum. Total tonnage mined increases from 24.4 Mt in Year 1 to a maximum of 88 Mt in Year 21.
The reporting standard adopted for the reporting of the Ore Reserve statement for the Hinda Project is that defined by the terms and definitions given in The 2012 Australian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves as published by the Joint Ore Reserves Committee of the Australasian Institute of Mining and Metallurgy, Australian Institute of Geoscientists and Minerals Council of Australia (JORC 2012).
The ore body is hosted by Upper Cretaceous (Maastrichtian) Holle Series and younger sediments situated within the Cretaceous to Quaternary terrestrial and marine succession. These sequences were deposited within intra-continental rift setting within the Congolese Coastal Basin. Geological data shows that the graben development is associated with a post Atlantic rifting event of salt dissolution in the late Cretaceous. The phosphates were deposited in a high energy environment which prevented clay deposition. The detrital terrigenous content is important and is dominated by quartz. As the paleo-environment changed, secondary dolomitic cement formed in sub-units of the series.
The average grade of P2O5 during the first 10 years production is approximately 12.5%, which is increased to 19.2% by simple screening, before beneficiation. Sectional interpretation of the data during the construction of the mineral resource domains confirms that the phosphate horizons are very consistent along strike. The location, depth, tenor and mineralogy of the deposit can therefore be predicted with a high degree of accuracy. The homogeneity was tested with a geostatistical study using variography, with lateral holes drilled on 10 m spacing and longitudinal every 25 meters. The Gm and Bm ore types display very high continuity with lateral ranges of up to 852, along and 370, across strike. Vertical continuity ranges of up to 5.5 meters are evident.
Geology and Resources
The phosphate deposit is located within a graben structure between 300 m and 800 m wide and extending for more than 20 km in a southern-east to northern-west direction. The depth to mineralisation is very shallow, less than 10 m in the south and slowly deepens northwards. The Ore body is between 40 and 65m thick.
The deposit is a large, structurally controlled and confined sedimentary accumulation of primary biogenic and secondary phosphate mineralisation. There are two main phosphate-bearing sedimentary layers. The Grey Maastrichtian (Gm) upper cretaceous layer represents the primary phosphate rock, providing 90% of the ore. Upper layers of the Gm unit have been subjected to tropical weathering and decarbonatation and the resulting weathered layer is designated Beige Maastrichtian (Bm).
Mineralisation is homogenous along and across strike. The orientation is well suited to a strip-mining type sequence that commences in the south and moves northwards. See the cross section from the southern area of the deposit. The graben host structures can be seen on the West (left) and East (right) side of the Ore body.