Instance: w23
- Contents:
- Information
- File downloads
- Solution files
- UPIT
- CPIT
- PCPSP
- References
Information:
- Description:
- Partial mine (Phase #2 and #3)
- Block model:
- 74260 blocks of size 25x25x20 ft
- Precedences computed with a 45 degrees pit slope (8 levels)
- 4 destinations: Sulfide mill, Oxide mill, Oxide leach and Waste
- Blockfile columns detail:
- id x y z dest phase AuRec AuFA tons co3 orgc sulf Mcost Pcost Tcost
Tvalue Bvalue rc_Stockpile rc_RockChar
- Blockvalue computation
- UPIT & CPIT: percomputed using column Bvalue
- PCPSP: Computed using (AuFA x Recovery x $900 – Mcost – process cost
– transportation cost)*tonnage
- Process cost $28.28/ton (sulfide mill), $4.30/ton (oxide mill),
$1.12/ton (oxide leach) $0.033 (dump)
- transportation cost: 0.18 (sulfide mill), $0.22 (oxide mill),
$0.20 (oxide leach)
- Recovery is equal to column AuRec (sulfide mill), 92% (oxide
mill), 62% (oxide leach)
- Only sulfide blocks ('hsf','lsf','msf','smf','ssf') can go to sulfide mill. Oxide blocks ('ol','om','ow') can go
to oxide mill/leach. Other blocks ('ag', 'an', 'bf', 'cov') cannot be processed.
- Discount rate = 0.1
- Type of Constraints:
- C0 Capacity constraint (mine): Total extracted tonnage <= 68M
tons
- C1 Capacity constraint (sulf mill): Total processed tonnage <=
3.61M tons
- C2 Capacity constraint (ox mill): Total processed tonnage <= 1M
tons
- C3 Blending Constraint (sulf mill): Average sulf <= 4.5
- C4 Blending Constraint (sulf mill): Average sulf >= 3.8
- C5 Blending Constraint (sulf mill): total sulf/co3 <= 1.2
- C6 Blending Constraint (sulf mill): total sulf/co3 >= 0.85
- C7 Blending Constraint (sulf mill): Average co3 <= 1.6 (*)
- C8 Blending Constraint (sulf mill): Average otgc <= 0.6
- CPIT only includes capacity constraints
- (*) Note: Blending constraint C7 makes the problem trivial (the only solution is to not extract any blocks). We suggest to replace 1.6 by 3.6 to get non-trivial solutions.
File downloads:
Download the
Minelib data format specification.
Solution files:
UPIT
- Download: w23_upit.sol
- Objective value: 510,973,998
- Computed using Hochbaum's pseudoflow algorithm. [*]
CPIT
- Download: w23_cpit_gmunoz120723.sol
- Objective value: 392,226,063 (LP GAP 2.1%)
- Provided by Gonzalo Muñoz, and obtained from the LP relaxation using
a modified TopoSort heuristic. [*]
- Download: w23.LPcpit
- LP relaxation solution (not feasible)
- Objective value: 400,653,199
- Computed using a modified version of Bienstock & Zuckerberg
algorithm. [*]
PCPSP
- Download: w23.LPpcpsp
- LP relaxation solution (not feasible)
- Objective value: 387,693,394
- Computed using a modified version of Bienstock & Zuckerberg
algorithm.[*]
References:
- Daniel Bienstock,
Mark Zuckerberg (2010), Solving LP Relaxations of Large-Scale Precedence
Constrained Problems. IPCO 2010: 1-14
- Dorit
S. Hochbaum (2008), The Pseudoflow Algorithm: A New Algorithm for the
Maximum-Flow Problem. Operations Research 56(4): 992-1009
- Gonzalo Muñoz
(2012), Modelos de optimizacion lineal entera y aplicaciones a la
mineria. Master thesis, Dept. Mathematical Engineering, Universidad de
Chile.