For CHE 311 · Unit Operations

Size Reduction Lab

Four interactive modules that make comminution visible: a ball mill simulated ball by ball, the energy laws on one log–log chart, a jaw crusher and crushing rolls that nip or slip, and a closed grinding circuit you can balance. Every module has guided experiments and exam-style worked examples that set the controls for you.

Start with the ball millAll modules
Jaw crusher 1 m → 150 mm Crushing rolls 50 mm → 12 mm Ball mill + classifier 12 mm → 75 μm Coarse crushing (Kick) → intermediate (Bond) → fine grinding (Rittinger)

Modules

Ball mill

Discrete-element simulation of the charge: cascading, cataracting, centrifuging. Critical speed, release angle, power, and a step-by-step derivation of nc.

critical speedspeed regimesderivation

Energy laws

Bond's law with the work-index table, and Rittinger–Kick–Bond predictions from one test on a log–log chart that shows where each law applies.

work indexapplicabilitydE/dL = −C/Lᵖ

Jaw crusher & rolls

Animated Blake jaw crusher and crushing rolls: nip angle, the no-slip condition, maximum feed size, Taggart and roll capacities.

nip angleslippagecapacity

Size distribution & closed circuit

Sieve analysis to differential and cumulative plots with RRS and GGS fits; an animated mill–classifier circuit with its mass balance and circulating load.

D̄s, D₈₀RRS / GGScirculating load

What the exam asks, and where to practise it

Topic in BUET CHE 311 papersYearsPractise in
Critical speed of a ball mill: definition and derivation2012-13, 2016-17, 2018-19, 2019-20, 2022-23, 2023-24Ball mill · derivation stepper
Factors influencing ball-mill product size; ball-mill construction2011-12, 2017-18Ball mill · speed, filling, liner
Rittinger, Kick and Bond laws and their applicability2012-13, 2015-16, 2017-18, 2020-21, 2022-23Energy laws · chart
Crusher energy from a test (Rittinger / Kick)2016-17, 2023-24Energy laws · examples 2 and 3
Crushers and grinders with the forces they use; gyratory vs Blake2014-15, 2018-19, 2019-20, 2022-23Jaw & rolls · types table
Nip angle, slippage of wet limestone; crushing rolls2023-24 (and slide exercises)Jaw & rolls · animations
Closed-circuit grinding flow diagram; size distribution of products2013-14, 2014-15Size distribution · circuit
Real physics, real unitsThe ball mill runs a contact-force simulation in SI units in real time; crushers use the actual nip geometry.
Checked numbersEvery worked example is recomputed by a test script and matches McCabe–Smith–Harriott, Coulson & Richardson or the course solutions.
Phone friendlyControls stack under the animation; day and night themes; animations pause when you prefer reduced motion.