SMART DOG MININGTM
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HDC 900 Horizontal Centrifuge
A horizontal centrifugal
concentrator,
HCD 900 uses centrifugal force to efficiently concentrate fine
particles.
With the arrival of the HDC 900, a new low cost, highly efficient
fine particle gravity concentrator is now available.
Typical capacities for a HDC 900 are:
Diameter of
Feed Rate
Basket
Ft3/hr
Coal
Gold
mm
ton/hr
ton/hr
900
700
55.0
75.0
The HDC 900 is designed to process fine particle size material.
The top size particle it can handle is 1/4" (6.25 mm), normal
feed is 28 mesh (0.5 mm) x 0.
For gold or metal mining, the HDC 900 replaces table/flotation
plants with one piece of equipment in less than one eighth the floor
area.
In coal the HDC 900 replaces froth flotation/water-only cyclones.
In other applications, such as environmental clean-up or remediation
the HDC 900 is used in place of much more complex circuitry.
The HDC 900 provides a high capacity gravity concentrator with a
very small foot print.
It can be used in fixed or mobile operations (see SDM Modular Plant)
with feed capacities over 50 ton/hour depending on type of feed.
Presenting the new SDM High Density Centrifugal Jig
(HDC 900) and its applications to coal and mineral
processing.
The
HDC 900 is a new and unique machine for the high gravity processing
of very small (down to micron size) particles previously difficult
or impossible to separate by gravity.
The HDC 900 can solve many of the problems inherent in fine
particle processing today.
It is specifically applicable to fine coal (especially for
sulfur reduction) and precious metal processing.
The HDC 900 is adaptable to many different projects and
properties, from new plants to reprocessing tailings and waste from
old operations.
In
coal and mineral processing the goal is to separate the particles
into groups, those having value and those that do not.
The most efficient processing does this by using a natural
difference between one particle and another.
The relative density of the particles is the easiest to use.
Gold has a density of
15+ compared to
the waste material with a density of 2.3.
Coal has a density of
1.5 compared to
the non-coal material with a density of 2.3. For particles whose
size is large, this difference is sufficient to allow an easy low
cost separating means.
When particles become small in size, other factors make this
separation more difficult.
Most
small particle processing is done in a moving stream of water.
This water is used to transport the material being processed
and help carry the separated particles away from each other.
When processing particles 0.5 mm in size and larger and when
there is a large difference in density between the particles, a
water based gravity separation process is very efficient.
But, when the particles become smaller than 0.5 mm in size or
the density difference between the particles is small, the speed
with which the particles will move apart maybe less than the speed
at which the water is flowing.
This prevents the particles from separating. The HDC 900 is
the solution to this problem.
The
HDC 900 solution is to increase the force on the particles by
speeding up their movement.
Current available technology has increased this force by 5 to
10 times. This is a
significant improvement, but, still only works for a small range of
sizes and densitys.
Many small particle applications cannot be processed
economically with current technology.
Importantly, the HDC 900 can increase the force to 50 to 150
times which is much greater than any other available technology.
Thus, the HDC 900 can separate particles which were
heretofore impossible to separate.
Several technologies have been introduced such as fine heavy media
cyclones, column flotation, and air sparged cyclones to reach this
improved level. Fine
heavy media cyclones (uses magnetite ground to very small size) have
been used at a plant in Pennsylvania, USA.
Column flotation for coal (originally developed around 1900
but replaced by froth flotation) is in use at a few locations in
West Virginia and Kentucky.
Air sparged cyclones (using a fragile, high cost, special gas
permeable metal cylinder) are still in the developmental state.
Fine
heavy media cyclones are efficient and work well, but are expensive
to install and operate due to the complex nature of the media
(finely ground magnetite) recovery circuit.
Conventional heavy media uses a magnetite ground to be less
than .6 mm, this circuit uses magnetite ground to be less than .1
mm. To reduce losses of
the magnetite (reduce operating costs) a special multi-stage media
recovery circuit is required.
This requires more capital and operating costs than a
standard circuit. The circuit is also highly susceptible to
fluctuations in the feed.
Column
flotation and air sparged cyclones are variations on conventional
froth flotation. As
such they suffer some of the same limitations, i.e., lower
efficiency than gravity separation and not all coal is foldable.
They both use chemicals and have to have very clean water.
The chemical use also restricts the amount of water that can
be reused without adding other chemicals. The HDC 900 uses no toxic
chemicals, no reagents, and emits no noxious gases.
The
above processes are the most promising technologies, currently in
general use. All are
expensive and difficult to control.
For small particle processing the ideal choice would be a low
capital and operating cost gravity process that was tolerant of feed
and water fluctuations.
Figure
A below shows the processes currently in general use compared to the
HDC 900. All are
limited to particles larger than 0.5 mm or rely on
toxic chemicals which are expensive and difficult to control.
In many places in the world, the use of toxic or potentially
toxic chemicals for coal preparation is restricted or prohibited.
For fine particle processing the ideal choice would be a low capital
and operating cost gravity process that is tolerant of feed and
water fluctuations.
The
HDC 900 is a cross between horizontal centrifuges and jigs.
HDC 900s use the jigging principle assisted by centrifugal
force to efficiently concentrate small particles.
Its use extends the range for gravity concentrating into
areas currently restricted to froth flotation or chemical
processing.
Processing costs are inversely related to the feed particle size.
Coarse particles are easier to process than fine particles.
Most coarse processing is done by a gravity process. Gravity
processing depends on the specific gravity difference between the
concentrate and the tails.
Fine sizes may require multi-stage or sophisticated
circuitry.
To
date the best fine particle processing circuitry has been a
physio-chemical process (e.g., flotation).
Now, with the HDC 900, this will change.
A new low cost, highly efficient fine particle gravity
concentrator is now available.
Furthermore, the HDC 900
provides for a much better removal of sulfur and ash from
coal than any existing technology.
For
gold or metal mining a circuit similar to shown below would be used,
with the screen oversize reporting back to the grinding circuit.
The material processed must be amenable to gravity
processing. But beyond
that, the use of the HDC 900 will allow maximum capacity in a very
small package.
Furthermore the HDC 900 provides a much better and a much greater
recovery of material than any alternative technology.
In
coal operations the HDC 900 would be used instead of froth flotation
or water-only cyclones.
The following flow diagram shows typical coal circuit processing
1/4" x 0 feed. In a
coal operation the HDC 900 would become the fines cleaning circuit.
For deep cleaning, the HDC 900 could be a second stage
following a coarse first stage.
The first stage product being crushed to 1/4" x 0.
This would produce maximum sulfur rejection at maximum
combustible recovery.
The
HDC 900 will be extremely efficient in ash removal.
It can process any high ash, high sulfur feed.
Such high ash feeds are culm or gob piles such as those in
the eastern U.S., or low rank coals from central Europe.
These piles are uneconomical to clean with current circuitry
due to fine size of the inclusions or refuse.
Now with the development of
the HDC 900 these piles become economically
and environmentally recoverable.
In the
mining industry, capacity is usually expressed in ton/hour of dry
feed. Capacity is
dependent on the volume of total material (solids and water) that
can flow across the basket (bed) in a specific period of time.
It is also dependent on the average particle size being fed
to it. The smaller the
average particle size the lower the net throughput, because the
particles are closer together.
Jigs are dependent on the free settling of particles through
the mobile (pulsed) bed.
Whether the unit is processing coal, gold, or some other
material, the basic through put is the same on a volumetric basis.
The rated capacity in tons per hour is dependent on the
specific gravity of the material being fed.
The
HDC 900 can be used in fixed or mobile operations with feed
capacities over 100 ton/hour depending on the type of feed. Further,
it is relatively small in size for the HDC 900’s capacity to process
material. The HDC
900 has high efficiency, high recovery,
and high capacity.
The rated capacities for a HDC 900 are:
Diameter of
Feed Rate
Basket
Ft3/hr
Coal
Gold
mm
ton/hr
ton/hr
900
700
55.0
75.0
The
HDC 900 is a gravity concentrating device.
With a jig, separation is into layers with the heaviest
particles on the bottom and the lightest particles on the top.
The jig separates particles into two or more layers dependent
upon their relative differences in specific gravity.
To make this separation, three effects (hindered settling,
differential acceleration, and consolidation trickling) are the
principles behind this action.
In a
jig, raw feed enters at one end, flows across the jig and out the
other end. In a
standard jig, this is a flat ribbon of material constrained by the
edges of the jig. In a
HDC 900, the bed is wrapped into a cylinder with the material
flowing along the walls of the cylinder.
Below the feed is a deck in a flat jig and a basket in a HDC
900. Across this deck
or basket flows a bed of material.
In jigging, two effects make the separation.
The first is the opening or expansion of the bed. Secondly,
the expansion is followed by the collapse or closing of the bed.
Each opening and closing is called one jig cycle.
The opening allows the particles to move away from each
other, and during the closing hindered settling, differential
acceleration, and consolidation trickling cause the material to
separate into layers of different specific gravity.
Many
methods can be used to achieve good stratification, but unless the
stratified layers can be removed without remixing, all jigging
advantages are lost. The problems of successful removal of the
stratified layers have received a lot of attention to date.
Many of the differences between a successful jig and a poor
jig depend on the design of the system to remove the different
layers.
Removal of the bottom layers is usually achieved by allowing it to
go through the jig bed and report to the hutch.
A key to good jigging is how the two mineral species layers
are removed. The top
material reports over the weir with minimal bottom material.
And the bottom material reports to the hutch with minimal top
material.
In a
HDC 900, the design and operation of the refuse gate mechanism is
very important. If the
gate opening is too large, too much top product will report through
it. If the gate is too
small, too much bottom product will overflow the weir instead of
reporting to the hutch.
As feed and operating conditions change the gate setting must be
adjusted.
The
HDC 900’s proprietary and patented weir mechanism used in the
separation process overcomes problems associated with the
cylindrical shape of the bed to provide a uniform and precise action
for controlling both the flow of water and solids over the weir and
the extraction of
products.
In
summary:
1.
The HDC 900 is a new and unique patented coal preparation
system, applicable to a wide range of coal, minerals, and soil
remediation.
2. The
HDC 900 is ready for commercial production and use.
3. The
HDC 900 offers a low cost alternative to expensive and potentially
toxic processes for recovering fine coal.
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4. The
HDC 900 provides the best solution in the separation and removal of
sulfur and ash from the coal, recovery of minerals, and soil
remediation, all of which previously were either too difficult or
impossible to economically recover.
o
40+ years’ experience in the mining industry with strong mineral
processing experience in precious metals, copper, industrial
minerals, coal, and phosphate
o
Operational experience in precious metals, coal, and phosphate plus
in petrochemicals.
o
Extensive experience performing studies and determining feasibility
in the US and international (United States, Canada, Mexico, Ecuador,
Columbia, Venezuela, Chile, China, India, Indonesia, and Greece).
o
E-mail:
info@smartdogmining.com
