Comminution

Comprehensive Capability

Common dry comminution tests conducted by ALS for engineering purposes are listed below in order of specimen/particle size:

• Unconfined Compressive Strength (UCS) via two modern Servotronic hydraulic compression machines. Separate specimen tests conducted upon core specimens (either NQ, HQ, PQ diamond drill intervals of Cores drilled from Rocks).
• Bond Impact Crushing Test (CWi). A traditional test conducted upon a set of rock specimens (typically 10 or 20) sized between 50 to 75 mm with two parallel faces.
• Point Load Testing (PLT). A surface hardness test conducted upon selected specimens of typically >20 mm.
• Autogenous Media Competency Tests (AMC). A proprietary SAG Mill competency test consisting of a tumble drum of broken pieces of PQ core, with Bond Impact Crushing Tests (CWi) conducted on survivors.
• JK drop-weight test. Proprietary test developed by the Julius Kruttschnitt Mineral Research Centre (JKMRC) in Queensland, Australia conducted (under license) on selected specimen sets of various sizes from -50mm ore.
• SMC Tests. Proprietary test developed by the SMC Testing Pty Ltd conducted under license on a set of 120 particles at the preferred size of –31.5 +26.5 mm, or in decreasing order –22.4 +19.0 mm and –16.0 +13.2 mm. A mass of 20 kg is usually required.
• SAG Design (Starkey). Proprietary SAG Mill test (US).
• Bond Abrasion Index (Ai) conducted upon charges of -19+12.7mm ore via a rotating impeller incorporating a Bisalloy of 500 Brinell hardness steel paddle within a contra-rotating drum.
• Bond rod mill work index (RWi). Traditional dry grinding lock cycle test in a rod mill conducted on ore charges crushed to P₁₀₀ 12.7 mm.
• Bond ball mill work index (BWi). Traditional dry grinding lock cycle test in a ball mill conducted on ore charges crushed to P₁₀₀ 3.35 mm.
• Levin open circuit grindability test. Test to ascertain grind size product from a fixed specific energy input – utilising the Bond Ball Mill.

Comminution also extends to wet grinding/milling and also to ultra-fine grinding (UFG) using stirred media mills. ALS conducts the following wet grinding and UFG tests:

• IsaMill^TM
• Metso Jar Mill Test
• DRA Milling Test
• Metso Verti-mill
• Deswik Stirred Media Detritor
• Metprotech Mill

Similarly, comminution is also conducted at larger scale for high pressure grinding rolls (HPGR) and Pilot Semi Autogenous (AG/SAG/SABC) grinding. These items are discussed in more detail in our pilot operations section.