3
MATERIAL PROPERTIES
Principal material properties affecting design and operation
must be considered apart from the distinctive wet or dry,
cementitious or non-cementitious characteristics.
Density
Material density informs the impact force calcula-
tions, in addition to the overall capacity and throughput
considerations.
Hardness/Brittleness/Abrasiveness/Strength
Material hardness and abrasiveness inform the impact and
abrasion effect assessments: wear on the containing/trans-
ferring vessel(s). Friable or overly brittle material may not
be suitable for transfer due to a tendency to break down.
Basic material strengths – compressive and tensile – can fol-
low from the strengths required for the ultimate use – con-
crete, shotcrete, etc. – and guide in selection of that media
as well as the design of the handling conduits and devices.
Particle Size Distribution/Particle Shape
Particle size distribution influences a range of the design
characteristics and operating procedures, including velocity
and cleanout procedures. Particle shape influences velocity,
and shapes can influence segregation in transport.
TRANSFER DEPTH
The system height directly influences the velocity, includ-
ing whether terminal velocity may be reached (apart from
drag on the pipe walls). Depth also determines whether the
Coriolis effect should be considered in design (Appendix).
That can influence velocity as well as wear and general oper-
ation of the system. Depth-dependent velocity is a primary
factor in the impact force. Given the vertical or sub-vertical
alignment, drag along the pipe may be minimal but war-
rants evaluation.
DIAMETER: SLICKLINE/DROPLINE
The slickline/dropline diameter is a principal aspect of the
overall system capacity and operating characteristics. In
general, it is advisable to use a pipe diameter (inside) which
is 4 to 6 times the size of the largest particles to be dropped.
In addition to minimizing perimeter contact and wear, that
will minimize the tendency for material to bridge if the
flow ever is halted in transit by maintenance or operational
disruptions.
At the surface station, the charging arrangements may
entail a change in pipe diameter. Wear-resistant inlet inserts
have been used with success, typically configured for impact
resistance. These can be replaced without handling the
entire slickline. As an example, these can be a single pipe-
length ceramic-lined insert resting on the discharge orifice
of the feed hopper, protecting the orifice and main column
from the initial impact load. Additionally, they tend to cen-
ter the flow away from the perimeter of the slickline, initi-
ating plug flow characteristics and extending protection for
a further distance down the pipe.
In these authors’ experience (1), inlet and outlet
(and nearby) segments had wear at two to three times the
replacement frequency of the rest of the pipe columns,
apparently indicative of inlet/outlet turbulence. An upper
ceramic insert eliminated the concern in that area, and was
continued even when the entire column was changed to
ceramic. Collar inserts are discussed further in Borehole–
Collar Suspended and Borehole—Grouted in Place.
Monitoring pipe wear is prudent, using borehole and
pipe investigation techniques ranging from visual to ultra-
sound. If the pipe is in a shaft where periodic external
observation is possible, wear may be visible before progress-
ing to significant failure. Slickline maintenance is discussed
further in Slickline.
SURFACE STATION
The basic characteristics of the surface station for vertical
transfer systems follow from the respective conventional
system characteristics for handling the material being trans-
ferred. Climate-related weather enclosures are appropriate
but not addressed here in detail.
Load Size
Fundamental is the size of the receiving load at the bottom
of the transfer line, which in the cases of surface mixing
may be smaller than the original mixed load. A common
factor being that conventional surface mixers, stationary
and mobile, range larger than typical underground transit
mixers. When that is the case, or a reasonable expectation,
options for splitting or retaining part of the surface load
must be considered. It is prudent to design the surface hop-
per itself to the underground load size rather than the typi-
cally larger surface vehicle load size.
Hopper Configuration
The surface hopper can be a conventional and relatively
simple design. Provisos to that include:
Movability
Whether the slickline is shaft- or borehole-mounted, occa-
sion will arise for access to the pipe. In the case of shaft-
supported, access from above the collar may be needed
only for the collar segment(s), either for crane or a universal
MATERIAL PROPERTIES
Principal material properties affecting design and operation
must be considered apart from the distinctive wet or dry,
cementitious or non-cementitious characteristics.
Density
Material density informs the impact force calcula-
tions, in addition to the overall capacity and throughput
considerations.
Hardness/Brittleness/Abrasiveness/Strength
Material hardness and abrasiveness inform the impact and
abrasion effect assessments: wear on the containing/trans-
ferring vessel(s). Friable or overly brittle material may not
be suitable for transfer due to a tendency to break down.
Basic material strengths – compressive and tensile – can fol-
low from the strengths required for the ultimate use – con-
crete, shotcrete, etc. – and guide in selection of that media
as well as the design of the handling conduits and devices.
Particle Size Distribution/Particle Shape
Particle size distribution influences a range of the design
characteristics and operating procedures, including velocity
and cleanout procedures. Particle shape influences velocity,
and shapes can influence segregation in transport.
TRANSFER DEPTH
The system height directly influences the velocity, includ-
ing whether terminal velocity may be reached (apart from
drag on the pipe walls). Depth also determines whether the
Coriolis effect should be considered in design (Appendix).
That can influence velocity as well as wear and general oper-
ation of the system. Depth-dependent velocity is a primary
factor in the impact force. Given the vertical or sub-vertical
alignment, drag along the pipe may be minimal but war-
rants evaluation.
DIAMETER: SLICKLINE/DROPLINE
The slickline/dropline diameter is a principal aspect of the
overall system capacity and operating characteristics. In
general, it is advisable to use a pipe diameter (inside) which
is 4 to 6 times the size of the largest particles to be dropped.
In addition to minimizing perimeter contact and wear, that
will minimize the tendency for material to bridge if the
flow ever is halted in transit by maintenance or operational
disruptions.
At the surface station, the charging arrangements may
entail a change in pipe diameter. Wear-resistant inlet inserts
have been used with success, typically configured for impact
resistance. These can be replaced without handling the
entire slickline. As an example, these can be a single pipe-
length ceramic-lined insert resting on the discharge orifice
of the feed hopper, protecting the orifice and main column
from the initial impact load. Additionally, they tend to cen-
ter the flow away from the perimeter of the slickline, initi-
ating plug flow characteristics and extending protection for
a further distance down the pipe.
In these authors’ experience (1), inlet and outlet
(and nearby) segments had wear at two to three times the
replacement frequency of the rest of the pipe columns,
apparently indicative of inlet/outlet turbulence. An upper
ceramic insert eliminated the concern in that area, and was
continued even when the entire column was changed to
ceramic. Collar inserts are discussed further in Borehole–
Collar Suspended and Borehole—Grouted in Place.
Monitoring pipe wear is prudent, using borehole and
pipe investigation techniques ranging from visual to ultra-
sound. If the pipe is in a shaft where periodic external
observation is possible, wear may be visible before progress-
ing to significant failure. Slickline maintenance is discussed
further in Slickline.
SURFACE STATION
The basic characteristics of the surface station for vertical
transfer systems follow from the respective conventional
system characteristics for handling the material being trans-
ferred. Climate-related weather enclosures are appropriate
but not addressed here in detail.
Load Size
Fundamental is the size of the receiving load at the bottom
of the transfer line, which in the cases of surface mixing
may be smaller than the original mixed load. A common
factor being that conventional surface mixers, stationary
and mobile, range larger than typical underground transit
mixers. When that is the case, or a reasonable expectation,
options for splitting or retaining part of the surface load
must be considered. It is prudent to design the surface hop-
per itself to the underground load size rather than the typi-
cally larger surface vehicle load size.
Hopper Configuration
The surface hopper can be a conventional and relatively
simple design. Provisos to that include:
Movability
Whether the slickline is shaft- or borehole-mounted, occa-
sion will arise for access to the pipe. In the case of shaft-
supported, access from above the collar may be needed
only for the collar segment(s), either for crane or a universal