Note: Descriptions are shown in the official language in which they were submitted.
~ 2177~5
-- 2
SEP~D~TION QF MTNFD)~
This invention relates to the separation of different
media based on differences in density, surface tension
5 ef f ects and general relative settling rates of the
different media over a range of particle 6izes.
The process described is applicable to various
minerals that must be separated for various reasons. In
particular, one of the most important and useful
10 separations that the system or process has been developed
for is the separation of mercury from mercury contaminated
soils, sands, gravels, clays and process sludges, (such as
chlor-alkali sludges) .
Many sites in the world have become contaminated to
15 at least some degree with heavy metals, especially
mercury, as a result of previous and/or on going
industrial operations owing to accidents and/or occasional
leaks or spills. In some instances the potential
environmental impact is minimal; in others it is serious
20 and could represent a danger to large numbers of people
Mercury is one of the heavy metals that could fall into
this latter category (i.e. dangerous to the environment).
Clean up of such industrial wastes in an ef f icient
manner represents a c~nt~nl~;ng challenge for industry and
25 a moral obligation for ever,vone associated with industry
and engineering. Systems are being used and improvements
are being made in these systems or processes in an effort
to ensure that we can eventually clean up our environment.
Thus, the invention broadly relates to a process for
30 the separation of higher density minerals from lower
density minerals comprising supplying material in the form
of a mixture of liquid and particulate material in a
selected particle size range to a hydraulic mineral
separator; maintaining a generally upwardly flowing stream
35 of liquid in said separator while said mixture is supplied
to the upwardly f lowing stream such that higher density
minerals fall downwardly by gravity forces against the
21775~
-- 3
upwardly flowing steam while the lower density minerals
are moved upwardly by said stream; and removing the
downwardly moving higher density minerals from said
separator through a lower discharge opening while the
5 upwardly moving lower density minerals are removed via an
upper outlet opening.
It is significant and possibly vital factor in the
hAnrll; nr~ of mercury r~ntAml nAted material that one of the
basic physical aspects or properties of mercury must be
10 contended with and managed properly. This characteristic
is that o~ the mercury possessing a very strong tendency
to break up into extremely f ine particles when it is
processed or agitated by physical means such as screening,
pumping or any handling that involves attrition or any
15 rapid movement, shaking or distortion of the mercury by
applied forces during handling or processing. If the
cleaning of the c~ntAm; nAted material is to be successful
it is vitally important that (a) a minimum of this fine
and often residue coated or "floured~ mercury is produced,
20 (b) that, if produced, that it be controlled before it
escapes to the discharge water and into the water
treatment circuit. If any mercury ie lost as extremely
fine or "floured" mercury it is then i~ a form most
dangerous to the environment and could most readily enter
25 the food chain. The significance environmentally of
f~l ;m;n~t;nrJ thig general problem of fine mercury particles
discharge or escape cannot be overstated. It is likely,
in f act, that if the problem of very minor carry over of
extremely fine mercury is not basically solved we will be
30 creating a more difficult clean up problem in the future.
Accordingly, an important aspect of the invention, in
cases wherein the higher density, (higher specific
gravity) mineral is mercury, (a portion of which is in the
form of very fine or resldue coated mercury particles
35 which tend not to settle downwardly within the separator),
provides for the application of eonic vibrations to the
liquid and mixture contained in the hydraulic separator to
21 7755~
-- 4 --
induce the mercury particles to coalesce together and form
larger particles which more readily settle downwardly
toward the lower outlet end of the separator thereby to
enhance the recovery of the mercury.
According to a further aspect of the invention there
is provlded apparatus for the separation of higher density
minerals from lower density minerals comprising a
hydraulic mineral separator including: means defining an
upright flow paesage; means for supplying process liquid
to said passage to r~;nt~ln a generally upwardly moving
stream of liquid therein during use; means for supplying
a mixture of liquid and particulate material to be
separated to said passage; an overf low means above said
passage for discharging liquid and lower density
particles; a discharge means below said passage for
discharging liquid and higher density particles which have
moved down by gravity against the upf lowing stream of
liquid; and vibrator means for effecting sonic vibrations
in the mi~ture of particulate material within said passage
to cause coalescence of selected finely divided metallic
minerals to erhance recovery of same via said discharge
means .
In the preferred form of the invention the ap~aratus
is adapted for the recovery of finely divided metallic
mercury particles.
By utilizing sonlc vibrations to effect coalescence
of the finely divided mercury, it has been found that the
carry-over of this extremely fine mercury can be
dramatically reduced, thereby cutting down on the size and
cost of the final water treatment process by a major
degree. This technique enables the previously
c~ nt~:m;ni~ted material to be returned safely to the natural
environment .
Another problem concerns the fact that very stubborn
retention of fine mercury is encountered when processing
organic type particles, especially such as peat and
related materials. In these cases the fine mercury cannot
=, , _ _ _ , , . , . . _ . .
21 ~7~
be removed by normal washing procedures even when combined
with extended agitation in water It therefore became
necessary to treat this type of material in a different
manner, ln order to obtain removal of the combined
mercury.
Accordingly, a further aspect of the invention
involves the conditioning of the material to be treated
and separated with a suitable conditioning compound. The
conditioning compound may be added to process water that
is sprayed on the mercury cr1n~m;n~ted material, starting
at the f eed hopper and then in the screening stages . The
conditioning agent alters the surface tension differential
and other physical characteristics between the mercury and
the organic and semi-organic material in which it is
trapped, having an almost immediate effect on the mixture
that results in the release or freeing up of the mercury.
The preferred conditioning compound is hexa meta
phosphate, which compound is introduced at relatively low
percentage levels as described hereaf ter .
In the preferred form of the invention, the processes
described above are utilized in con junction with the
improved mineral separator as described and claimed in my
pending (~n~ n application Serial No 2,142,747 ~lled on
February 17, 199~ and entitled MINERAI SEPARATOR, naming
Michael Kuryluk as inventor and assigned to Phase
Remediation Incorporated The corresponding U. S patent
application was filed on ~une 16, 1995 receiving Serial
No 08/470,994, the disclosure of which patent application
i6 incorporated herein by reference thereto
In the preferred practice of the invention, the sonic
vibrational forces are applied to selected chambers of the
mineral separator to er~ance the recovery of the f inely
divided mercury The vibrational system is preferably
controlled automatically such that it can be adjusted to
preform most ef~ectively for the process conditions at the
time .
In cases where organlc particles such as peat and
21 77~5
related materials are involved, the conditioning agent
noted above is utilized in con~unction with the above
apparatus to great advantage thereby to release or free-up
the entrapped mercury particles.
Preferred embodiment3 of the invention will now be
described with reference to the accompanying drawings.
BRI13F DE;S( K I v,LJL5.).N OF T~E v~nS OF nR~WTMrq
FIG. l is a schematic flow diagram showing a typical
separation process in accordance with the invention;
FIG. 2 is a elevation view, partly in cross-section,
of the preferred ~orm of mineral separator l1~;1;7e~1 in the
process;
Fig. 3 i8 a simplified diagram illustrating and
explaining the riffles provided in the upper funnel;
Fig. 4 is an elevation view of a water dilution
chamber, and
Fig. 5 is a plan view of a water dilution chamber;
Fig. ~ is a diagrammatic illustration of the several
stages involved in the coalescence of f inely divided
mercury particles into larger particles;
Fig. 7 is a diagrammatic representation of a portion
of the hydraulic mineral separator showing the application
of vibrators to the settling stages of the separator in
accordance with the preserlt invention;
Figs. 8, 9 and l0 are fld~ ry views of a mineral
separator employing an alternative mechanical arrangement
for imparting vibrations to the settling stage of the
hydraulic separator;
Fig. ll is a sketch of typical peat moss
subst~nt;~11y magnified illustrating the manner in which
mercury particles become entrapped therein.
nT.!T~TT.T~n ~T~!~qrRTp~IoN OF ~ K I~ KK ~:1 ) T'MP.( )l ) I M ~ LS
Referring firstly to the schematic flow diagram of
Fig. l, the ma~or stages in the overall process are
illustrated. The infeed, which will be assumed to be
mercury-contaminated media, is fed on a relatively steady
continuous basis via a hopper l0 and a feeder 12 over an
-
-- 7
automatic scale. A limited amount of water may be added
at this time (usually with a surface active compound, to
be described hereafter), to improve the separation of the
mercury from the material being fed.
The mixture now f low3 or is conveyed onto a coarse
vibrating screen 14 (e . g . 1/4 " mesh) where the material is
spray water washed along with the addition of any desired
amount of surface active compound. The oversize cleaned
material (1/4" size or less) is conveyed to storage or
rescreened if necessary before being stored or returned to
its origin.
Undersized material from the first stage or stages of
screening is passed on to another screen 16 of finer mesh
(e.g. about 10 mesh) for similar treatment. The coarse or
oversized clean material is returned or conveyed to
storage or rescreened if necessary before being stored or
returned to its origin.
The undersized material from the second stage or
stages o~ screening is routed to a series of vibrating
screens 18, pre~erably of the "Sweco" type, where the
material is again washed by water sprays (including any
desired surface active compound) over finer mesh screens
(20 to 30 mesh). The undersized material (mainly process
water and fine silt together with some entrained mercury)
is routed to at least one mineral separator 30 or, as
shown, to a plurality of such separators 30 for removal of
the mercury and its recovery. As shown, the overflow from
the first mineral separator 30 again passes into a series
of vibrating screens 22 o~ the Sweco type, these screens
being very fine (e.g. about 60 mesh). At the same time
the material is washed with sprays of water together with
the surface active compound if required. The oversized
material (greater than 60 mesh) is again conveyed to
storage or rescreened if necessary before being stored or
returned to its origin. The very fine material left,
which is of less than 60 mesh size, forms the infeed for
the second hydraulic mineral separator 30 and the overflow
21 775~
-- 8
from this second mineral separator, conslsting of process
water and relatively light mercury-free particulate
material, is put into a settling and f inal water treatment
tank 2g. Suitable chemicals may be added at this point to
assist in the settling treatment, following which the
process water is passed through an activated carbon bed 25
with the outflowing process water being recycled and fed
back into the first and second mineral separators 30 along
with any required fresh makeup water (either fresh or
salt).
Practically pure mercury is recovered f rom the lower
small outlet end of each separator 30 for storage and re-
use .
It was mentioned previously that in the pref erred
form of the invention, the hydraulic mineral separator
used is essentially that as described and claimed in the
pending ~anadian patent application Serial No. 2,142,747
filed February 17, 1995 entitled MINERA~ SEPAR~TOR naming
Michael H. Kuryluk as inventor and in its corresponding
~.S. counterpart patent application Serial No. 08/470, 994
filed June 16, 1995. Before proceeding further, a
description of this mineral separator will be incorporated
herein and the ilu~LU~ tS which have been made to it
will be described thereafter.
- By way of general explanation, the description
cr nt;lin~-~l below makes reference to "heavy" particles and
"light" particles or similar terms. It is to be
understood that the terms "heavy" and "light" refer to
particles or materials having, relative to one another,
3 o high or low densities or specif ic gravities; they do not
refer to the mass of the particles. A large ~light~'
particle could have more mass than a smaller ~heavy~'
particle .
Ref erring to Figure 2, the pref erred separator
apparatus is generally indicated at 30. It includes an
upper cone-shaped wall 32 having an upper end 3g which is
closed by a cover member 36 defining a funnel-shaped or
21 77
. ~
g
conical upper chamber 38. An overflow tube 40 connects to
chamber 38. The lower end 42 of the upper chamber 32 is
connected to a conical mixing chamber 44 which has a first
or upper dilution chamber 46 connected to its upper end
5 and a second or lower dilution chamber 48 connected to its
lower end. The lower side of dilution chamber 48 is
connected to a lower conical portion 50 which, in turn, is
connected to a high velocity tube or pipe 52, having its
lower end disposed in a low velocity chamber 54. Chamber
10 54 is c~nn~ l with a concentrate collector 56 having a
discharge tube 58. The exit diameter of tube 58 must be
smaller than the ;nt~rn~l diameter of high velocity tube
52 80 that substantially more of the water supplied at
pipe 60 to chamber 54 will enter tube 52 rather than exit
15 via discharge tube 58.
Water ls fed from a water 6upply (not shown) to a
pipe 62 as indicated by an arrow at the end of the pipe
62 . From ther~ the water f lows through a valve 64 which
is regulated in a pulsed on-off manner by a timed on-off
20 pulse ewitch or actuator 66, for a reason to be explained
later. A by-pass valve 68, normally closed, may be
opened, and valve 64 closed, if it is desired to provide
a steady f low of water to chamber 54 .
An agitator or mixer 70 is rnounted for rotation on
25 brackets 72 attached to the main support for the apparatus
partially shown at 74, so that the agitator is suspended
within the upper chamber 38. The agitator can be rotated
by a drive arrangement 76 via an endless belt or chain 78.
Rotation speeds may be varied to suit the size and density
30 of the materials being separated. A typical rotation
speed i8 4Q rpm.
Figures 4 and 5 show the structure of a dilution
chamber, in this case dilution chamber 46. The dilution
chambers provide a means of local water velocity control.
35 Water from a variable control feed source (not shown) is
fed to dilution chamber 46 via an inlet tube 80 connected
to an annular di~tributor ring 82 ~rom which water is fed
21 77~a 5
-- 10 -
through multiple feeder pas~ages 84 into the mixing
chamber 44. The added water creates a centrifugal
spinning motion and increases the verti cal water velocity
allowing additional control over particle settling rates
5 by variation in the water Eeed rate. The diameter and
number of feeder pas6ages may vary, as may the vertical
and horizontal angles of the passages 84. Any number of
dilution chambers may be used, two being shown in Figure
2. The dilution chambers n~ ;nt;l;n a fluidized bed of
10 material in the lower section of the upper chamber 38.
Referring to Fig. 2, the inner surface of the upper
cone-shaped wall 32 i8 provided with a number of sluice
riffles 86. Although not shown in Figure 2, Figure 3
illustrates a riffle 86. It is illustrated as roughly
15 triangular in cross-section but could be of some other
6hape such as rectangular. Variations may be made in the
number, length, width, height, position, material and
cross-sectional shape and angle of attachment to the wall
32. Preferably, the riffles run essentially straight up
20 and down the inner surface of wall 32. The riffles act as
turbulators, similar to riffles in a conventional gold
sluice, behind which zones of zero or very low velocity
occur as indicated at 88 when the agitator 70 is rotating.
These zones of zero or low velocity 88 allow settling out
25 of fine (small size) heavy particles. Gravity acts on the
particles in the stagnant "dead-zone" 88, causing them to
move downwardly along the riffle 86 towards the base of
the chamber 3 8 .
As shown in Figure 2, the agitator 70 includes a
30 hollow shaft 90 provided with a plurality of openings 92.
Material mixtures to be separated are fed into the top of
the hollow shaft as indicated by arrow 94 and exit into
chamber 38 via the openings 92. However, this is only one
possible means for feeding material to chamber 38; it
35 could, for example, be fed into the chamber 38 through an
opening in the chamber wall 32 instead of through the
shaft 90. The agitator 70 includes a plurality of vanes
21 77~5
or paddles 96 running parallel to the inner wall of the
upper chamber 38 and spac~d therefrom so as to pass close
to the riffles 86 when the agitator 70 is rotated.
Rotation of the vanes 96 of the agitator 70 causes the
5 contents of upper chamber 32 to swirl around past the
riffles 86, creating the "dead-zones" 88.
In operation of the apparatus shown in the drawings,
water is fed to the lower chamber 54 by main water feed 60
at a rate selected, based on experimentation, in
10 accordance with the materials to be separated. Most of
the water flows into high velocity pipe 52 and up to upper
chamber 38 while some water (and separated material) flows
out of discharge tube 58. Additional water is added, in
mixing chamber 44, via dilution chamber 48 and in the
15 lower end of chamber 38 via dilution chamber 46. The
total water flow rate provided by the main water feed 60
and the dilution chambers 46 and 48 i8 adjusted so that
material having a density higher than a predetermined
f igure can move downwardly against the upward f low of
20 water while materials having a density lower than the
predetermined figure cannot. The agitator 70 is caused to
rotate and materials to be separated are fed in via the
hollow shaft 90. Because of the rotation of agitator 70,
which causes the water and the particles therein to swirl
25 around in the upper chamber 38, fine particles of material
of high density present in the water are subj ected to
centrifugal forces and tend to move out to the wall of the
upper chamber 3 8 where they become caught in the " dead-
zones'~ 88 behind the rlffles 86. These fine particles of
30 heavy material can then move downwardly along the wall of
chamber 3 8 and then along the wall of mixing chamber 44
until eventually they are e~ected from discharge tube 58
together with the larger sized heavy particles which have
suf f icient mass to be able to move downwardly against the
35 upward flow of water. Because of the centrifugal forces
created by the rotating agitator, fine particles of heavy
material are directed to the wall of the chamber out of
~ 21 775S~
-- 12 --
the comparatively fast upward flow of water which would
otherwise carry them out of the over~10w 40. Water exits
the apparatus via overf low tube 4 0, carrying materlal
having a density less than ~he predetermined f igure .
As r~n~;on~l above, the main water feed 60 is
preferably regulated at a pulsed rate by valve 64
activated by timed on-off switch 66. The pulsing is
necessary on a continuous feed operation to allow any
accumulated f~n~ ntrate in high velocity pipe 52 to flow
10 into the low velocity chamber 54 and then on to the
c on~Pntrate collector 56 while the main water flow i8
m~m-~n~rily interrupted. When the main water flow
resumes, the material in the concentrate collector 56 is
forcefully ejected via discharge tube 58. The exit
15 diameter of tube 58 muet be of smaller diameter than the
internal diameter of high velocity tube 52, as discussed
above. By adjusting the water fIow rate and on-off pulse
rate, the optimum discharge rate of concentrate may be
achieved. The apparatus is, however, capable of being
20 operated manually.
~ Iaving now described the basic mineral separator
structure forming the subject matter of the patent
applications referred to above, we will now describe the
coalescing system that is to be incorporated in the
25 mineral separator described above. This system, which i8
basically a sonic vibrational system, is to be
incorporated in the lower settling stages of the
separator. This system is used to cause the rapid but
staged coalescing of the very f ine or f loured mercury
30 particles. By way of further explanation it is known by
those experienced in this field that fine mercury globules
with clean metallic surfaces easily coalesce; however,
this is not the case with fine mercury particles
particularly as found in chlor-alkali sludge produced in
35 the chlor-alkali process. The6e particles have been found
to be coated with extremely fine residues from the
process, which coatings in effect: set up a barrier around
21 77~55
-- 13 --
each particle. Because of the above-described nature of
these particles they are not amenable to gravity
separation or coalescing and normally pass through to the
process tailings thus decreasing the efficiency of the
recovery operation.
The coalescing system i8 best illustrated in Fig. 7
which shows a portion of the mineral separator 3 0 . In
particular, the system employs the use of four vibrators
mounted on the exterior of the separator as illustrated.
Two vibrators 100 are diametrically opposed and fixed to
chamber wall 32 adjacent the lower end of the upper
chamber 38. These vibrators lO0 should be positioned a
distance upwardly from the bottom end of upper chamber 38
which is equal to about 1/4 to about 1/3 the total length
"X" of the chamber wall 32. In similar ~ashion a further
pair of vibrators 102 are positioned diametrically
opposite one another flxed to the wall of and adjacent the
lower end portion of the mixing chamber 44. The vibrators
100 and 102 are preferably Model H1-V1 vibrators
manufactured by ERIEZ, Series ~ These vibrators are
driven and controlled from a variable speed solid state
controller 104 also preferably by ERIEZ. This controller
has a range of up to 3600 vibrations per minute (60 Hz) on
60 cycle current.
It has been found that optimum coalescing of the fine
mercury in relatively coarse materials (from about 20 to
about 60 mesh range) occurs between 2000-3000 vibrations
per minute. For finer materials, down to the 30 micron
range, the optimum range appears to be from about 2500-
3400 vibrations per minute based on preliminary testing.
However, it should be understood that the nature of the
slurry in the separator can vary significantly, i.e. the
slurry can include silica grains, carbon, mixtures of
these and others, including silt and clay fractions all of
which affect somewhat the optimum vibration rate required
for maximum coalescing. Routine testing and
experimentation should enable those skilled in the art to
2t 77S5~
-- 14 -
provide suitable operating parameters for all materials
likely to be processed by this technique. Stated
differently, each ~n~tl~rl~l to be coalesced will have a
more or less critical resonance level at which the
particles of necessity will coalesce.
The coalescing process is illustrated in Fig. 6 . In
the first stage there is shown multiple pairs or groups of
f inely divided mercury globulee each being coated with
fine residues as described previously. In stage 1 these
globules are separate and distinct from one another.
E~owever, with the application of the sonic vibrational
energy, the vibrations in the liquid medium tend to break
the surface coating thus exposing the mercury and allowing
the coalescing of the mercury particles which then move as
larger particles into stage 2 and, while being c~nt;nll;3lly
subject to the vibrational energy, again coalesce together
to form still larger particles in stage 3. At this or
some subsequent stage of coalescence the ~ercury particles
will become big enough 80 as to separate out and settle
downwardly by gravity, enabling same to move downwardly
through the lower stages of the separator 3 0 as described
above to be eventually discharged through the exit tube
58 .
An alternative form of vibrator system is illustrated
in Figs. 8, 9 and 10. This system comprises a mechanical
vibrator which is positioned within the cavity of the
separator well down into the settling section of same.
With reference to Fig. 8, the mechanical vibrator is
driven by a conventional 60 cycle, 1725 RPM electric motor
110 supported on mounting bracket 112 and aligned to drive
pulley 114 which in turn drives a flexible drive cable 116
(see Fig. 10) which extends downwardly through the hollow
mixer shaft 90 supported by bearing housing 118. In
effect this configuration is a rotating shaft 116 within
an outer rotating shaft 90.
Because of ~ the u~e of the hollow mixer shaf t 9 0 as a
carrier for the flexible drive shaft 116, it becomes
-
21 77~5
- 15 -
necessary to provide the wall 32 o~ upper chamber 38 with
a feed port 120 (see Fig. 9) through which the mixture to
be separated is fed into the separator.
The submersible vibrator is shown in detail in Fig.
5 10. An elongated rubber housing 122 is secured to the
lower end of shaft 90 by means of a stainless steel clamp
ring 124. The cavity 126 defined by rubber housing 122 is
filled with lightweight oil (No. 1 oil).
The vibrations are supplied by an eccentric shaft 128
10 journalled by two small roller bearing assemblies 130
positioned in spaced apart relationship as shown in Fig.
10, which in turn are held in place within the rubber
housing 122 via means of two stainless ~3teel clamp rings
132. The upper end of the eccentric shaft 128 is firmly
15 secured to the lower end of the fle2~ible drive cable 116.
Hence, during operation, as electric motor 110 drives the
drive pulley 114, the eccentric shaft 128 is rotated thus
imparting vibrational energy through the oil contained in
the rubber housing 122 to the walls of this housing and in
20 turn imparting sonic vibrational energy to the mixture
,-,,nt~inPr~ in the mixing chamber 44 within which the rubber
housing 122 is disposed as clearly illustrated in Fig. 9.
During operation, the sonic vibrational energy thus
generated serves to ef f ect coalescence o~ the f inely
25 divided mercury particles in essentially the same manner
as described previously.
It was noted previously that suitable conditioning
agents (surface active compounds) could be added to the
process water which is sprayed onto the contaminated
30 material, beginning at the initial stages of the operation
at the ~eed hopper 10 and continuing through the various
screening stages. The principal reason for adding a
conditioning material relates to the fact that test work
has revealed that very stubborn retention of f ine mercury
35 is encountered when processing organic type particles
especially peat and related materials. Reference may be
had to Fig. 11 which is a diagrammatic sketch of a
21 77~5
-- 16 --
fragment of peat moss material showing the intricate
network of cellular structures; because of its porosity
and interc~nn~ tf~ cellular structure, the mercury
particles become trapped therein and held by capillary and
5 possibly molecular and ionic forces. In these casee the
f ine mercury cannot be removed by normal washing
procedures even when combined with extended agitation in
water . It theref ore i~ necessary to treat this type of
material in a somewhat different manner in order to obtain
10 removal of the entrapped mercury particles.
The treatment developed involvee the conditioning of
the cont~m;n~ted material with a compound known as sodium
hexametaphoephate at relatively low percentage levels.
This conditioning compound i8 added to all process water
15 that is eprayed on the mercury ~-,,n~m; n~ted material
starting at the feed hopper 10 (see Fig. 1) and then
during the subsequent screening stages, reference being
had to screens 14, 16, 18 and 22. This conditioning agent
alters the surface tension differential and other physical
20 characteristics between the mercury and the organic and
semi-organic material in which it is trapped, having an
almost immediate effect on the mixture which results in
the release or freeing-up of the mercury.
Sodium hexametaphosphate is commerclally available
25 and is sold under the trademark "CAIGON". Typical Calgon
usage varies depending on the percentage of organic
material present in the mercury cont~m;n~ted material
being treated and varies depending on the particle size
range of this material. This results in a rather wide
30 range in the amount of Calgon required for any given feed
to the system and may vary between a trace addition up to
0.5 to 1.0 grams per 1000 grams of process water.
Obviously, for purposes of economy, the amount of Calgon
added should be kept as low as reasonably possible
35 consistent with good recovery of mercury. A small amount
of routine experimen~ation in any given situation will
quickly reveal the amounts of Calgon required for any
21 77~5~
- 17 -
particular application. Other types of similar
conditioning compounds such as Giltex; Quadrafos; Hagan
Phosphate and Micromet (which are mixtureg C~n~i~;n;n~
sodium hexametaphosphate as the principal agent) may also
5 be used.
The conditioning of the ~aterial to be treated thus
involves the use of the above-described conditioners as
indicated in the flow sheet of Fig. 1 covering the
treatment of mercury contaminated media; inorganic,
10 organic or mixtures thereof and they fall under the
general description of surfactants and detersive systems.
Full descriptions of these systems can be found in the
standard chemical technology literature; such as Volume 22
of the "Encyclopedia of Chemical Technology" Third
15 Edition, John Wiley & Sons or the "Encyclopedia of
Chemistry" Third Edition, Reinhold Publishing Corp. This
latter work states, "It ha~ been known for many years that
the polyphosphates are strong complexing agents, and this
property has formed the basis of a number of industrial
20 applications for these materials". In general, it is
found that the chain phosphates (especially the longer-
chain materials) form complexes with a wide variety of
cations, ranging from the alkali metals to the transition
metals " . (Encyclopedia of Chemistry) . " . . . detergent
25 refers to a combination of surfactants with other
substances, organic or inorganic, formulated to enhance
functional performance, specifically cleaning, over that
of the surfactant alone". (Encyclopedia of Chemical
Technology) . Those skilled in the art will understand
3 o that in the use of the term conditioning we mean to cover
the use of compounds or mixtures of compounds that may be
characterized by the use of the term detergent or
surfactant. These compounds, or mixtures of these,
constitute a pool of products that can be drawn on for use
3 5 as conditioning agents in the system described herein and
are intended to constitute a part of this process when
used as al~ lntegral part of the process, i.e. in ~he
21 77~55
- lB -
washing and screenlng ~tages.
EXAMP~ OF ~ W~lR~T~G PR0~ESS
One example of a working process follows:
The feed is natural geological media, i.e. till,
5 consisting of 3 " stone down to sub-micron clays . See
table immediately below.
3" to 1/4 49~ (Oversize Material)
1/4 to 20 Tyler mesh 1096 (Undersize material)
-20 mesh to 60 mesh 609
-60 mesh to 100 mesh 1596
-100 mesh 11~
Typical size range for primary screen is 1/4" mesh
15 Tyler. Typical size for the secondary screen is 10 mesh.
The average soil being treated at this ~ite will run
approximately 80g~ silica. The feed routinely ran 3
mercury by weight. The feed slurry ran, on average 20~6-
25~ solids, at a total average feed rate of 2.5 to 3.0
20 metric tormes/hour and a~ high as 5 metric tonnes/hour.
Tertiary ~creen 1 is a 20 mesh ~creen. Tertiary screen 2
is a 60 mesh screen. Tertiary screen 1 feeds separator
No. 1 and Tertiary screen 2 feed separator No. 2. Screen
1 above has a cleaned discharge of -10 to +20 mesh (i.e.
25 less than 10 to greater than 20 mesh) material and screen
2 has a cleaned discharge of -20 to +60 ~ands. Both
discharge~ are mercury free below acceptable level~ of
0.25 PPM.
The overflow from separator No. 2 carries sands with
30 a grain slze average of -60 mesh, which is routed to the
settling ~ystem and carries routinely values in the range
of 0 . 25 PPM . This settling system constitutes the f irst
stage of the settling and water treatment system; here the
suspended solids are removed by a standard water treatment
35 system of precipitation by coagulation using aluminum
21 7755~
-- 19 --
sulphate (e~uivalent) in a restricted Ph range of 4 or
less. The cleaned water is stripped o~ trace levels of
any metals remaining by use of an activated carbon
filtration system. This polishing step yields a finished
5 water that routinely has levels of mercury acceptable - to
municipal water treatment plants. This water constitutes
the recycled water used in the process.
Preferred embodiments of the invention have been
described and illustrated by way of examples. Those
10 skilled in the art will realize that various modification3
and changee may be made while still rf~;n-ng within the
spirit and scope of the invention. ~ence the invention is
not to be limited to the embodiments as described but,
rather, the invention encompasses the full range of
15 equivalencies as defined by the appended claims.
