Comminution is particle size reduction by breaking, crushing, or grinding of ore, rock, coal, or other materials.

It is a critical component in most mineral processing flowsheets and can serve several purposes, including:

  • Liberating valuable minerals that are locked within waste rock
  • Increasing available surface area for chemical reactions
  • Producing particles within a particular size range to meet product specifications

In order to properly evaluate the crushing and/or grinding characteristics of a material, Hazen engineers must first consider the size distribution, shape, and nature of the feed material. In addition to a full complement of laboratory and pilot-scale size-reduction equipment, we also have the necessary classification and particle size determination facilities. Working with the Mineralogical Laboratory, we develop and optimize size reduction flowsheets.

Comminution Descriptions and Costs (Cost, US$)

Breakage Characterization – JKTech Procedures: full drop-weight test procedure, requires 80 to 100 kg of minus 4 in. (100 mm) material: $5,500

  • This test determines the energy vs. breakage distribution function for five ore sizes from 13 to 63 mm and uses these functions to determine crusher performance and autogenous/semiautogenous milling characteristics. These ore-specific parameters are used in grinding circuit simulation and modeling using the JKSimMet software.

SAG Mill Comminution (SMC) Test: requires 15 kg of ¼ core or 20 kg of minus 2 in. (50 mm) rock: $2,200

  • This test uses the same procedure as the full drop-weight test, except it uses only one size fraction at five energy levels.

Bond Rod Mill Grindability: requires 25 kg of minus ½ in. material: $950

  • This test determines the Bond Rod Mill Work Index, which can be used with Bond’s Third Theory of Comminution to calculate net power requirements of sizing rod mills. The test is a closed-circuit, dry grindability test, is run in a standard rod mill, and can be performed at sizes ranging from 4.76 mm to 210 microns. The normal finishing size is 1.2 mm.

Bond Ball Mill Grindability: requires 15 kg of minus 6 mesh material: $950

  • This test determines the Bond Ball Mill Work Index, which can be used with Bond’s Third Theory of Comminution to calculate net power requirements for sizing ball mills. The test is a closed-circuit, dry grindability test is run in a standard ball mill, and can be performed at sizes ranging from 595 mm to 37 microns. The normal finishing size is 149 microns.

Bond Abrasion Test: requires 1.6 kg material, ¾ by ½ in.: $400

  • This test determines the Bond Abrasion Index, which can be used to determine steel media and liner wear in crushers, rod mills, and ball mills. The equipment consists of a rotating drum, into which the dry ore sample is placed, with an impact paddle mounted on a center shaft rotating at a higher speed than the drum. The paddle is made of a standard alloy steel hardened to 500 Brinell. The abrasion index is determined from the weight loss of the paddle under standard operating conditions.

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