2
operating data. The E1B mix box appears to have been rede-
signed by Fluor Daniel Wright in 1994 and replaced. The
Winters Company, as part of the Loaded Organic Wash
project had revised flow sheet values as 6,000 gpm nominal
and 7,000 gpm design PLS and 6,420 gpm nominal and
7500 gpm Organic flows.
The original Brown and Root structural design of the
mix box itself was of 10-gauge 316L stainless steel sheet
acting as a false floor and liner for a reinforced concrete
box. The later design by Fluor shows a 1/4” plate design
for the false floor inserted in essentially the same configu-
ration. The pump mixer originally procured and installed
by Brown and Root, Tag No. 232-W-008, consisted of a
Lightnin Model 77- Q-40 Extraction Pumping Mixer
with an R301 6-bladed 85.5” diameter straight radial vane
impeller with 10.5” wide vanes driven at 42 rpm by a 40 hp
1200 rpm motor and right- angle speed reducer.
FAILURES AND REPAIR HISTORY
Since construction, a long history of yielding and metal
fatigue related failures and subsequent solution leaks into
the facility containment have occurred on the sidewalls
and false floor of the primary mix boxes. Adverse hydrau-
lic loading appeared to have initiated premature failure of
much of the box structure.
Over the course of a typical year an SX train would
require multiple shut-downs to drain the system, clean the
boxes, and locate and repair cracks by welding. See Figures
1 and 2 for typical plate repairs. Some cracks were very dif-
ficult to locate and resulted in some being missed and not
repaired, negating much of the benefits of the repair effort.
Repairs were also being attempted in extremely cramped
confined spaces presenting a myriad of potential hazards
and requiring a variety of controls.
Freeport initiated a mix box replacement program
around 2001 at the Chino SX Operation in Vanadium, New
Mexico. CAID Industries, a mining technology equipment
fabricator and supplier in Tucson, Arizona, was contacted
to develop a reinforced drop-in replacement that could be
installed within a short time-frame, which was subsequently
successfully accomplished. Learnings coming from issues
with the replacement boxes informed design improvements
by CAID prior to attempting replacements at the Morenci
operation in 2007 at the Central SX Plant where flows were
higher and larger primary mixers employed.
A preliminary design from CAID was provided to
Freeport in 2011 for the Metcalf SX E1B mix box. A sub-
sequent request from Freeport was made for a third-party
analysis of the efficacy of the replacement along with the
development of a concise study report. The findings from
that initial basic study of the original 1986 and proposed
2011 mix box designs including the mix box hydrodynam-
ics and structural analysis follow.
Table 1. Operating conditions for FMI Morenci Metcalf SX E1B Mix Box
Stream
Flowsheet
Nominal
Flowsheet
Maximum
Field Data
2/8/2012 Study 1 Study 2
PLS flow (gpm) 6,000 7,000 7,650 7,800 12,000
Organic flow (gpm) 6,420 7,500 3,700 3,600 6,200
Pump mixer speed 42 rpm @60 Hz -37 rpm @53 Hz 37 rpm @53 Hz 40 rpm @57 Hz
Figure 1. Typical fatigue cracking repair
Figure 2. Fatigue crack repair
operating data. The E1B mix box appears to have been rede-
signed by Fluor Daniel Wright in 1994 and replaced. The
Winters Company, as part of the Loaded Organic Wash
project had revised flow sheet values as 6,000 gpm nominal
and 7,000 gpm design PLS and 6,420 gpm nominal and
7500 gpm Organic flows.
The original Brown and Root structural design of the
mix box itself was of 10-gauge 316L stainless steel sheet
acting as a false floor and liner for a reinforced concrete
box. The later design by Fluor shows a 1/4” plate design
for the false floor inserted in essentially the same configu-
ration. The pump mixer originally procured and installed
by Brown and Root, Tag No. 232-W-008, consisted of a
Lightnin Model 77- Q-40 Extraction Pumping Mixer
with an R301 6-bladed 85.5” diameter straight radial vane
impeller with 10.5” wide vanes driven at 42 rpm by a 40 hp
1200 rpm motor and right- angle speed reducer.
FAILURES AND REPAIR HISTORY
Since construction, a long history of yielding and metal
fatigue related failures and subsequent solution leaks into
the facility containment have occurred on the sidewalls
and false floor of the primary mix boxes. Adverse hydrau-
lic loading appeared to have initiated premature failure of
much of the box structure.
Over the course of a typical year an SX train would
require multiple shut-downs to drain the system, clean the
boxes, and locate and repair cracks by welding. See Figures
1 and 2 for typical plate repairs. Some cracks were very dif-
ficult to locate and resulted in some being missed and not
repaired, negating much of the benefits of the repair effort.
Repairs were also being attempted in extremely cramped
confined spaces presenting a myriad of potential hazards
and requiring a variety of controls.
Freeport initiated a mix box replacement program
around 2001 at the Chino SX Operation in Vanadium, New
Mexico. CAID Industries, a mining technology equipment
fabricator and supplier in Tucson, Arizona, was contacted
to develop a reinforced drop-in replacement that could be
installed within a short time-frame, which was subsequently
successfully accomplished. Learnings coming from issues
with the replacement boxes informed design improvements
by CAID prior to attempting replacements at the Morenci
operation in 2007 at the Central SX Plant where flows were
higher and larger primary mixers employed.
A preliminary design from CAID was provided to
Freeport in 2011 for the Metcalf SX E1B mix box. A sub-
sequent request from Freeport was made for a third-party
analysis of the efficacy of the replacement along with the
development of a concise study report. The findings from
that initial basic study of the original 1986 and proposed
2011 mix box designs including the mix box hydrodynam-
ics and structural analysis follow.
Table 1. Operating conditions for FMI Morenci Metcalf SX E1B Mix Box
Stream
Flowsheet
Nominal
Flowsheet
Maximum
Field Data
2/8/2012 Study 1 Study 2
PLS flow (gpm) 6,000 7,000 7,650 7,800 12,000
Organic flow (gpm) 6,420 7,500 3,700 3,600 6,200
Pump mixer speed 42 rpm @60 Hz -37 rpm @53 Hz 37 rpm @53 Hz 40 rpm @57 Hz
Figure 1. Typical fatigue cracking repair
Figure 2. Fatigue crack repair