optimizing crusher output (case study)
TRANSCRIPT
OPTIMIZING CRUSHER OUTPUT
• Theoretical Assumptions• Field Observations• Recommendations
Theoretical AssumptionsVRM OPERATING CAPACITY 240 TONS/HOUR
OPERATING TIME 24 HOURS
VRM Requirements 5760 TONS/DAY
LIMESTONE 90% 5184 TONS
SILICA 9% 518.4 TONS
PYRITE 1% 57.6 TONS
BDP RATED CAPACITY
CRUSHER CAPACITY 450 TONS/HOUR 500 TONS/HOUR
CRUSHER OPERATING TIME 12 HOURS
TOTAL CAPACITY 5400 TONS/DAY 6000 TONS/DAY
TRUCK FACTOR 22
TRIPS PER DAY 246 273
TRIPS PER HOUR 20.45 22.75
TRUCK DUMPING INTERVAL 2.93 MINUTES 2.64 MINUTES
January and February
Total Production based on Weighfeeder
Trips per day
March and April
Trips per day
Total Production based on Weighfeeder
ELEMENTS OF THE CYCLE
THEORETICAL:
Travel from Crusher to Extraction Area
Loading
Travel from Extraction Area to Crusher
Dumping
BASED ON OBSERVATION:
Travel from Crusher to Extraction Area
Waiting for Loading
Loading
Travel from Extraction Area to Crusher
Dumping
Computing the required number of samples5 preliminary samples
elements 1 2 3 4 5 X 1 2 3 4 5 X2 samples
crusher to extraction 3 2 2 2 2 9 4 4 4 4 25
waiting 6 6 3 7 4 36 36 9 49 16 146
loading 3 2 2 3 2 9 4 4 9 4 30
Extraction to crusher 4 4 4 3 3 16 16 16 9 9 66
dumping 1 1 1 1 1 1 1 1 1 1 5
total cycle time 17 15 12 16 12 72 289 225 144 256 144 1058 8
Using the formula :
Actual Time Chartas observed May 2, 2012; 1:30-3:00pm
Travel Time from Crusher to Extraction Area
Waiting Time for Loading
Loading Time
Travel Time from Extraction Area to Crusher
Dumping Time
Area: AQUINO WESTLoading equipment = 4m3 bucket capacity
TRUCK 1 TRUCK 2 TRUCK 3
Minor causes of delayas observed(May 2, 2012; 1:30-3pm)
• Path suddenly blocked• Sudden equipment maintenance• Dumptruck waits for dumped limestone to go down the hopper
before dumping its own load• Backhoe operator attends to personal needs
_______ delay• The back hoe is scraping rocks to be loaded to the dump trucks.
Loading unit = 3.67m3 bucket capacity
No. of passes Duration seconds sec/pass7 3 180 25.71429
6 2 120 20
7 3 180 25.71429
6 3 180 30
6 2 120 20
6 3 180 30
6 2 120 20
6 3 180 30
6 3 180 30
6 3 180 30
5 2 120 24
6 2 120 20
6 2 120 20
6 1 60 10
6 2 120 20
6 2 120 20
6 1 60 10
6 3 180 30
6 3 180 30
5 2 120 24
6 2 120 20
6 2 120 20
6 3 180 30
6 2 120 20
5 1 60 12
5 3 180 36
7 4 240 34.28571
7 2 120 17.14286
6 1 60 10
6 2 120 20
6 2 120 20
6 2 120 20
6 2 120 20
6 1 60 10
6 2 120 20
7 3 180 25.71429
Average 6.02 2.25 22.34921
Tons
Bucket Capacity 9.17
Truck capacity 22
No. of Passes 2.4
No. of passes Duration Seconds Sec/Pass
14 3 180 12.85714
12 5 300 25
13 3 180 13.84615
12 4 240 20
16 6 360 22.5
11 5 300 27.27273
17 6 360 21.17647
14 4 240 17.14286
16 5 300 18.75
15 5 300 20
15 6 360 24
16 5 300 18.75
15 5 300 20
Average 14.31 4.769231 20.09964
Loading unit = 1.7m3 bucket capacity
Tons
Bucket Capacity 4.23
Truck capacity 22
No. of Passes 4.20
1 minute interval between loading of each truck
TRUCK 1 TRUCK 2 TRUCK 3
ELEMENT TIME Frequency
Travel from Crusher to Extraction Area
4 mins
Loading 3 mins 14
Travel from Extraction Area to Crusher
4 mins
Dumping 40 secs 12
Travel Time from Crusher to Extraction Area
Loading Time
Travel Time from Extraction Area to Crusher
Dumping Time
Addition of another truck
TRUCK 1 TRUCK 2 TRUCK 3 TRUCK 4
ELEMENT TIME Frequency
Travel from Crusher to Extraction Area
4 mins
Loading 3 mins 18
Travel from Extraction Area to Crusher
4 mins
Dumping 40 secs 16
Travel Time from Crusher to Extraction Area
Loading Time
Travel Time from Extraction Area to Crusher
Dumping Time
1 minute interval between loading of each truck
TRUCK 1 TRUCK 2 TRUCK 3
ELEMENT TIME Frequency
Travel from Crusher to Extraction Area
4 mins
Loading 3 mins 19
Travel from Extraction Area to Crusher
4 mins
Dumping 40 secs 17
Travel Time from Crusher to Extraction Area
Loading Time
Travel Time from Extraction Area to Crusher
Dumping Time
Addition of another truck
TRUCK 1 TRUCK 2 TRUCK 3 TRUCK 4
ELEMENT TIME Frequency
Travel from Crusher to Extraction Area
4 mins
Loading 3 mins 25
Travel from Extraction Area to Crusher
4 mins
Dumping 40 secs 23
Travel Time from Crusher to Extraction Area
Loading Time
Travel Time from Extraction Area to Crusher
Dumping Time
TRIPS PER HOUR 23
TRUCK FACTOR 22
CRUSHER
OPERATING TIME 12
PRODUCTION PER HOUR 506
PRODUCTION PER DAY 6072
NUMBER OF TRUCKS 4
LOADING EQUIPMENT 1
Rest pauses are important for the following reasons:• They break up the monotony of the day. • They give workers the chance to recover from fatigue and to
attend to personal needs.• They reduce the amount of time off taken by workers during
working hours.• Where workers are working in conditions of heat, cold, noise
or vibration it may be necessary to introduce mandatory rest pauses as part of a work--rest routine to ensure the health and safety of the workers.
Recommendation• To eliminate backing
Widen hopper
This allows dump trucks to continue dumping even though crusher is not yet operating, or is experiencing a down time.