3702 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
PROCESS DESIGN CONSIDERATIONS
The flowsheet targeted for this evaluation considers multi-
stage crushing, high pressure grinding, and conventional
ball milling. Run of Mine ore is fed to a gyratory crusher
where product is screened, fed to a secondary cone crusher,
and delivered to a coarse ore stockpile. Ore is metered and
fed to High Pressure Grinding Rolls (HPGR), which oper-
ates in closed circuit with a vibrating screen. The vibrat-
ing screen controls the top-size material which is delivered
downstream for further ball milling. The ball mill also oper-
ates in closed circuit with a bank of hydrocyclones which
classifies the mill product and directs hydrocyclone over-
flow for separation. Figure 1 depicts the comminution cir-
cuit modeled.
For this HPGR-ball mill flowsheet, a 66,000 Metric
Tons per Day (MTPD) copper concentrator was selected to
be evaluated. Ore characteristics reflect medium hardness
ore with a typical grinding circuit product size requirement
of 80% passing 75 microns. Process input data for the ball
mils is summarized in Table 1.
EQUIPMENT SELECTION
Grinding Mill Selection
Considering the input process details provided earlier as
well as identification of the flowsheet, two different ball
mill selections were made for this application. Ball mill
selections are as follows:
Quantity (3) 27'-0" × 44'-0" Flange-Flange [43'-6"
EGL] Ball Mills with 18.6MW installed each
Quantity (2) 30'-0" × 53'-0" Flange-Flange [52'-6"
EGL] Ball Mills with 28.0MW installed each
Both selections were made considering a total installed
grinding mill circuit power of 56 MW. Mill geometry and
installed power allow for normal milling circuit utilization
factors to ensure the mills can accommodate fluctuations
in feed characteristics and slightly coarser feed as upstream
screens wear during operation.
Table 1. Process design criteria
Input Data Values
Ore Type Copper
Ore SG 2.72
Daily Throughput (MTPD) 66,000
Availability (%)92%
Hourly Throughput (MTPH) 2,990
Bond Work Index (kWH/mT) 16.0
Axb 29.5
Feed Size, 80% Passing (microns) 4,000
Product Size, 80% Passing (microns) 75
Recirculating Load (%)400
Figure 1. HPGR-BALL Mill Flowsheet
PROCESS DESIGN CONSIDERATIONS
The flowsheet targeted for this evaluation considers multi-
stage crushing, high pressure grinding, and conventional
ball milling. Run of Mine ore is fed to a gyratory crusher
where product is screened, fed to a secondary cone crusher,
and delivered to a coarse ore stockpile. Ore is metered and
fed to High Pressure Grinding Rolls (HPGR), which oper-
ates in closed circuit with a vibrating screen. The vibrat-
ing screen controls the top-size material which is delivered
downstream for further ball milling. The ball mill also oper-
ates in closed circuit with a bank of hydrocyclones which
classifies the mill product and directs hydrocyclone over-
flow for separation. Figure 1 depicts the comminution cir-
cuit modeled.
For this HPGR-ball mill flowsheet, a 66,000 Metric
Tons per Day (MTPD) copper concentrator was selected to
be evaluated. Ore characteristics reflect medium hardness
ore with a typical grinding circuit product size requirement
of 80% passing 75 microns. Process input data for the ball
mils is summarized in Table 1.
EQUIPMENT SELECTION
Grinding Mill Selection
Considering the input process details provided earlier as
well as identification of the flowsheet, two different ball
mill selections were made for this application. Ball mill
selections are as follows:
Quantity (3) 27'-0" × 44'-0" Flange-Flange [43'-6"
EGL] Ball Mills with 18.6MW installed each
Quantity (2) 30'-0" × 53'-0" Flange-Flange [52'-6"
EGL] Ball Mills with 28.0MW installed each
Both selections were made considering a total installed
grinding mill circuit power of 56 MW. Mill geometry and
installed power allow for normal milling circuit utilization
factors to ensure the mills can accommodate fluctuations
in feed characteristics and slightly coarser feed as upstream
screens wear during operation.
Table 1. Process design criteria
Input Data Values
Ore Type Copper
Ore SG 2.72
Daily Throughput (MTPD) 66,000
Availability (%)92%
Hourly Throughput (MTPH) 2,990
Bond Work Index (kWH/mT) 16.0
Axb 29.5
Feed Size, 80% Passing (microns) 4,000
Product Size, 80% Passing (microns) 75
Recirculating Load (%)400
Figure 1. HPGR-BALL Mill Flowsheet