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Table 13-11: BBWi Classification

Waterberg Technical Report

Based on the above classification, the Early Mine Blend is very hard to mill.

Historically, the 2019 DFS ores were classified as listed below (at a 106 µm closing screen) for each ore zone.

• T-Zone samples were hard with BBWi values ranging from 18.3 kWh/t to 20.1 kWh/t.

• F-Central samples were very hard with BBWi values ranging from 19.9 kWh/t to 26.1 kWh/t.

The latest comminution test work result of 27.5 kWh/t is higher than the upper limit of the previously reported 2019 DFS composite sample BBWi, which reported a maximum BBWi value of 26.1 kWh/t. Based on the results, modification to the milling circuit design is not required for the first three years of LOM.

13.2.3 Historic Comminution Test Work

Comminution test work on the following Waterberg Project lithology units was conducted at Mintek between 2013 and 2016: T-South (T2a sample), F-Central (F4 sample), F-Boundary drill cores, and F-North drill cores. The comminution characterization test work scope included SAG mill comminution (SMC) tests, uniaxial compressive strength (UCS) tests, Bond crushability work index (CWi) tests, Bond abrasion index (Ai) tests, Bond rod work index (BRWi) tests, Bond ball work index (BBWi) tests, and Mintek grind mill tests.

Due to the metallurgical drill core sample being available in different core sizes and fractions (i.e., half core, ¾ core, or full core), the samples were not all subjected to identical testing. At a minimum, each sample was subjected to BBWi and Mintek grind mill testing. This allowed for comparison and benchmarking of the different samples against each other by means of various simulation methods. Refer to Table 13-12 for a summary of the results on the tests conducted per lithology unit.

Waterberg Technical Report