# Model:Morrell SS SAG

## Contents

## Morrell Mi (SMC) single-Stage SAG Mill Model

This is a SAG or AG mill model that estimates the specific energy consumption (E_{SAG}) using the equations of Morrell (2004).

### Testwork Required

- The SMC™ test, stored in the "DWT" testwork table (SMC is a Drop Weight Test).
- Bond ball mill work index. The method requires
**all the parameters**of the ball mill work index test to be filled in:- Ball mill Wi test closing screen size,
*umclosing*, µm - Ball mill Wi test product size,
*P*, µm_{80} - Ball mill Wi test feed size,
*F*, µm_{80} - Ball mill Wi grams per revolution at test conclusion,
*gpr*

- Ball mill Wi test closing screen size,

### Required parameters

**F**is the 80% passing size of the fresh feed to the circuit (expected to be a Bond-compatible size distribution)._{80}, µm**P**is the 80% passing size of the circuit product (expected to be a Bond-compatible size distribution)._{80}, µm**Availability**, expressed as a decimal (0.90 = 90% availability) is used to convert t/h to t/d.

### Optional parameters

**Description**and**Comment**are optional text fields**Maximum t/h limit**is a t/h throughput above which a warning message is displayed (but does not actually limit the throughput).**CFsag calibration factor**, model tuning factor for E_{ASAG}

### Formulae

The method is superficially similar to Bond (among other models), but with a variable exponent on size defined by:

Where *x* is the particle 80% passing size in µm.

SAG with pebble crushing circuit: ^{Morrell, 2004}

SAG with pebble crushing circuit: ^{Morrell, 2004}

Circuits with a pebble crusher have an extra term to account for the pebble crusher specific energy, which requires an estimate of the pebble crusher F_{80} (*PEB*, the size of the pebbles as µm) and the pebble crusher product P_{80} (approximately the crusher's closed side setting as µm, *CSS*). The quantity of material passing through the pebble crusher is also required, expressed as a fraction of the fresh feed rate to the SAG circuit. Pebble crushers are expected to operate in open circuit, so the open circuit factor 1.19 applies.

^{Morrell, 2009}

For the purposes of simulations (and because the E_{peb} term tends to be small), the following conditions are assumed:

- fraction of circulating load = 0.15
- pebble crusher CSS (P
_{80}) = 12.5 mm - pebble dimension (F
_{80}) = 35 mm

### CF_{sag} calibration factor

The *CF _{sag}* factor is used to reflect the effect of

**pebble crushing**on the overall circuit performance. This value is automatically selected if you leave this field blank in the model configuration settings.

- Base value, SAB circuit (no pebble crushing, ~6 inch SAG feed), CF
_{sag}= 1.00 - Pebble crushing, SABC circuit, CF
_{sag}= 0.95