2
conduits, controls and devices used in dropline/slick-
line systems, but some design, operation, and main-
tenance characteristics are common.
Reception volume – the volume of the receiving vessel or
chamber must be large enough to accept the load(s)
without occluding the discharge orifice. This relates
primarily to the height from the vessel/chamber floor
and the final discharge – which discharge may be a
material handling hose or pipe extension below the
boot.
Slickline – vertical free-fall transfer conduit for wet media.
These are wet-mixed media (aggregates, concrete,
shotcrete). Liquid-only transfer (water, fuels, lubri-
cants, etc.) is not grouped with slicklines, but is
touched on here regarding slickline preparation and
cleanout.
Sub-collar – the workings immediately below a collar. In
a typical shaft, these provide access for utility entry
without congesting conveyance access, and can be
constructed for a number of design objectives.
Wet transfer – this is media which is wet-mixed prior to
transfer, typically concrete and shotcrete. It can
include sand and aggregates without cement, which
to eliminate dust generation are wetted above typical
bank moisture.
WET/DRY TRANSFER
A driving condition in the design and operation of a verti-
cal transfer system is whether it will function as a wet or
dry system. Wet systems are commonly termed slickline
systems, though not like petroleum or pumped concrete
arrangements which also use that term. Dry systems have
been called dropline systems, which also is nomenclature
with other uses.
Both wet and dry media can be transferred, in which
case design and operation considerations must address
aspects of both uses. Wet, especially cementitious mixes,
may tend toward plug rather than segregated flow. That
will affect velocity and impact force. Line preparation and
washdown can be critical for slickline – wet – operation.
The three groups of media primarily addressed in this
paper are:
Concrete/Shotcrete
Concrete and shotcrete in shaft sinking were the initial uses
for slicklines (Appendix). Behavior and treatment of these
media in and after slicklines typically departs from conven-
tional handling methods, especially for long drops. Though
manufacturers can provide reasonable starting points
for mix designs, some degree of field practice and testing
should be expected in order to establish recipes which will
reliably meet the mine’s needs.
Guidelines presented (op. cit.) include that as a slug
of concrete drops, it creates a trailing vacuum that pulls
moisture so the slump at the shaft bottom is lower than
the slump measured at the collar. Concomitantly, the loss
of potential energy is converted to heat, thus the concrete
temperature increases from collar to shaft bottom.
As a rule, different media are not handled in the same
system because coarse aggregate may compromise the shot-
crete equipment. If the gradations are similar, combined
systems can be used though diligent cleanout still would
be in order.
In shaft sinking, transfer typically is wet directly into
final placement. In mine development and operation,
these media are transferred wet or dry, as the overall system
calls. Dry transfer typically is to an underground station-
ary mixer, which subsequently discharges to transit mixers
or other transports. Wet transfer commonly is to transit
mixers.
Aggregate
Aggregates typically are transferred either for mixing under-
ground with binder, or for placement as uncemented fill,
possibly road base. Separate aggregate transfer can be either
for backfill or concrete/shotcrete, as designed. It is common
to use concrete/shotcrete systems for neat aggregate transfer
when required. The specific material property requirements
will depend on the end use.
Binder
Binder in this paper includes solid admixtures such as fly
ash which also are transported in slicklines or droplines.
Typically, unmixed binder is transferred dry to a mixer
underground, where it is mixed for end use. Sole binder
transfer must be dry, with potential moisture eliminated or
controlled, whether strata-bound or aerial/meteoric.
It is common to bring binder from offsite in standard
bulk transport vessels, either rail or highway. From there it is
transferred to intermediate surface storage, typically bins or
silos equipped with dust control systems and valved to han-
dle the media. Discharge into the dropline can be through
a screw conveyor with conventional rotary valves (airlock)
to prevent silo runout (Belt/Screw Feed). Additionally, if the
pressure differential from dropline collar to underground
outlet compromises the airlock integrity, a vacuum release
or a combined vacuum and pressure release valve may be
installed at the dropline collar. These are further discussed
in Vacuum Break/Pressure Release.
conduits, controls and devices used in dropline/slick-
line systems, but some design, operation, and main-
tenance characteristics are common.
Reception volume – the volume of the receiving vessel or
chamber must be large enough to accept the load(s)
without occluding the discharge orifice. This relates
primarily to the height from the vessel/chamber floor
and the final discharge – which discharge may be a
material handling hose or pipe extension below the
boot.
Slickline – vertical free-fall transfer conduit for wet media.
These are wet-mixed media (aggregates, concrete,
shotcrete). Liquid-only transfer (water, fuels, lubri-
cants, etc.) is not grouped with slicklines, but is
touched on here regarding slickline preparation and
cleanout.
Sub-collar – the workings immediately below a collar. In
a typical shaft, these provide access for utility entry
without congesting conveyance access, and can be
constructed for a number of design objectives.
Wet transfer – this is media which is wet-mixed prior to
transfer, typically concrete and shotcrete. It can
include sand and aggregates without cement, which
to eliminate dust generation are wetted above typical
bank moisture.
WET/DRY TRANSFER
A driving condition in the design and operation of a verti-
cal transfer system is whether it will function as a wet or
dry system. Wet systems are commonly termed slickline
systems, though not like petroleum or pumped concrete
arrangements which also use that term. Dry systems have
been called dropline systems, which also is nomenclature
with other uses.
Both wet and dry media can be transferred, in which
case design and operation considerations must address
aspects of both uses. Wet, especially cementitious mixes,
may tend toward plug rather than segregated flow. That
will affect velocity and impact force. Line preparation and
washdown can be critical for slickline – wet – operation.
The three groups of media primarily addressed in this
paper are:
Concrete/Shotcrete
Concrete and shotcrete in shaft sinking were the initial uses
for slicklines (Appendix). Behavior and treatment of these
media in and after slicklines typically departs from conven-
tional handling methods, especially for long drops. Though
manufacturers can provide reasonable starting points
for mix designs, some degree of field practice and testing
should be expected in order to establish recipes which will
reliably meet the mine’s needs.
Guidelines presented (op. cit.) include that as a slug
of concrete drops, it creates a trailing vacuum that pulls
moisture so the slump at the shaft bottom is lower than
the slump measured at the collar. Concomitantly, the loss
of potential energy is converted to heat, thus the concrete
temperature increases from collar to shaft bottom.
As a rule, different media are not handled in the same
system because coarse aggregate may compromise the shot-
crete equipment. If the gradations are similar, combined
systems can be used though diligent cleanout still would
be in order.
In shaft sinking, transfer typically is wet directly into
final placement. In mine development and operation,
these media are transferred wet or dry, as the overall system
calls. Dry transfer typically is to an underground station-
ary mixer, which subsequently discharges to transit mixers
or other transports. Wet transfer commonly is to transit
mixers.
Aggregate
Aggregates typically are transferred either for mixing under-
ground with binder, or for placement as uncemented fill,
possibly road base. Separate aggregate transfer can be either
for backfill or concrete/shotcrete, as designed. It is common
to use concrete/shotcrete systems for neat aggregate transfer
when required. The specific material property requirements
will depend on the end use.
Binder
Binder in this paper includes solid admixtures such as fly
ash which also are transported in slicklines or droplines.
Typically, unmixed binder is transferred dry to a mixer
underground, where it is mixed for end use. Sole binder
transfer must be dry, with potential moisture eliminated or
controlled, whether strata-bound or aerial/meteoric.
It is common to bring binder from offsite in standard
bulk transport vessels, either rail or highway. From there it is
transferred to intermediate surface storage, typically bins or
silos equipped with dust control systems and valved to han-
dle the media. Discharge into the dropline can be through
a screw conveyor with conventional rotary valves (airlock)
to prevent silo runout (Belt/Screw Feed). Additionally, if the
pressure differential from dropline collar to underground
outlet compromises the airlock integrity, a vacuum release
or a combined vacuum and pressure release valve may be
installed at the dropline collar. These are further discussed
in Vacuum Break/Pressure Release.