5,651,465
*Jul.29, 1997
[11]
[45]
1lUll 11111111 III 11111 11111111111111111111111111111111111111111111111111111
US005651465A
Patent Number:
Date of Patent:
United States Patent [19]
Schmidt et aI.
[54] BENEFICIATION OF SALINE MINERALS
[75] Inventors: Roland Schmidt, Lakewood; Dale Lee
Denham, Jr., Louisville, both of Colo.
[73] Assignee: Environmental Projects, Inc., Casper.
Wyo.
4,341,744
4,363,722
4,375,454
4,512,879
4,943,368
5,096,678
5,470,554
7/1982 Brison et aI 4231206 T
12/1982 Dresty, Jr. et aI. . 209/40
3/1983 Imperto et aI 2091214 X
4/1985 Attia et aI 209/40
7/1990 Gilbert et aI 209/40
3/1992 Mackie 423127
1111995 Schmidt et aI 209/131 X
[*] Notice: The term of this patent shall not extend
beyond the expiration date of Pat. No.
5,470,554.
[21] Appl. No.: 465,598
[22] Filed: Jun. 5, 1995
Related U.S. Application Data
OTHER PUBLICATIONS
Perry, Chilton and Kirkpatrick, Chemical Engineers Handbook,
4th Ed. (1963), pp. 21-61 to 21-70.
Perry, Chilton and Kirkpatrick, Chemical Engineers Handbook,
5th Ed. (1973) pp. 8-31.
Primary Examiner-William E. Terrell
Assistant Examiner-Than Nguyen
Attorney, Agent, or Firm-Sheridan Ross P.C.
References Cited
Continuation of Ser. No. 66,871, May 25, 1993, Pat No.
5,470,554.
Int. CI.6 B07B 15/00; C22B 26/00
U.S. CI 209/12.2; 209/31; 209/127.1;
423/206.2; 241/19; 241/24.1
Field of Search 209/3, 12.1, 12.2,
209/30-37.39.40. 17, 127.1, 128. 131,
214; 423/121, 206.2; 241/19, 24, 25
31 Claims, No Drawings
A process is provided for recovering a saline mineral from
an ore containing the saline mineral and impurities. The
process generally includes the steps of separating a first
portion of impurities from the ore by density separation,
electrostatically separating a second portion of impurities
from the ore, and magnetically separating a third portion of
impurities from the ore. The process can further include the
steps of crushing the ore and dividing the crushed ore into
a plurality of size fractions before the above-referenced
separating steps. Furthermore, in order to increase the efficiency
of the separating processes, the process of the present
invention may further include the steps of drying the ore to
remove surface moisture therefrom and de-dusting the ore to
recover valuable fines.
[57] ABSTRACT
4/1961 Porter 423/121
4/1966 Smith 23/63
6/1974 Graves et aI 423/206.1
3/1975 Sproul et aI 423/206.1
5/1980 Conroy et aI 423/206.2
8/1981 Brison et aI 209/166
U.S. PATENT DOCUMENfS
2,981,600
3,244,476
3,819,805
3,869,538
4,202,667
4,283,277
[63]
[51]
[52]
[58]
[56]
5,651,465
1
BENEFICIATION OF SALINE MINERALS
2
SUMMARY OF THE INVENTION
DETAllED DESCRlPTION OF THE
INVENTION
The present process is a dry beneficiation process for
recovering saline minerals from an ore containing the saline
mineral and impurities. The process includes separating a
first portion of impurities from the ore by density separation.
The process can further include electrostatically separating
a second portion of impurities from the ore, and/or magnetically
separating a third portion of impurities from the
ore. The present process can alternatively include crushing
the ore to achieve liberation of impurities and/or sizing the
crushed ore into fractions before the separating steps. The
present invention provides a process that beneficiates saline
minerals to a higher purity than prior known dry beneficiation
processes.
The process of the present invention is designed to
recover saline minerals from naturally occurring ores to
produce commercially valuable purified minerals. As used in
the mineral processing industry, the term "saline mineral"
refers generally to any mineral which occurs in evaporite
deposits. Saline minerals that can be beneficiated by the
present process include, without limitation, trona, borates,
potash, sulfates, nitrates, sodium chloride, and preferably,
trona.
The purity of saline minerals within an ore depends on the
deposit location, as well as on the area mined at a particular
deposit. In addition, the mining technique used can significantly
affect the purity of the saline minerals. For example,
by selective mining, higher purities of saline minerals can be
achieved. Deposits of trona ore are located at severallocations
throughout the world, including Wyoming (Green
River Formation). California (Searles Lake), Egypt, Kenya,
Venezuela, Botswana, Tibet and Turkey (Beypazari Basin).
For example. a sample of trona ore from Searles Lake has
been found to have between about 50% and about 90% by
weight (wt. %) trona and a sample taken from the Green
River Formation in Wyoming has been found to have
55
30
The present invention is embodied in a process for
recovering a high-purity saline mineral from an ore containing
the saline mineral and impurities. The process generally
5 includes separating a first portion of impurities from the ore
by a density separation method, electrostatically separating
a second portion of impurities from the ore, magnetically
separating a third portion of impurities from the ore.
10 In one embodiment, the density separation step can
include air tabling or dry jigging to separate impurities
having a different density than the saline mineral. In another
embodiment, the process of the present invention is used for
beneficiating trona from an ore containing trona and impu-
15 rities. In this embodiment, the first portion of impurities
removed by the density separation step comprises shortite.
In another embodiment of the present invention, a process
is provided for the production of purified soda ash for
production of caustic soda by the lime-soda process. The
20 process generally includes the steps of separating a first
portion of impurities from a trona-containing ore by a
density separation method, electrostatically separating a
second portion of impurities from the ore, magnetically
separating a third portion of impurities from the ore. The
25 product of the above-mentioned separation processes is used
to produce caustic soda. The process further includes solubilizing
aluminum hydroxide in bauxite by contacting the
bauxite with the caustic soda to produce a solution and
recovering alumina from the solution.
BACKGROUND OF THE INVENTION
Many saline minerals are recognized as being commercially
valuable. For example, trona, borates, potash and
sodium chloride are mined commercially. After mining,
these minerals need to be beneficiated to remove naturally
occurring impurities.
With regard to trona (Na2C03.NaHC03.2H20), highpurity
trona is commonly used to make soda ash, which is
used in the production of glass and paper. Naturallyoccurring
trona, or crude trona, is found in large deposits in
the western United States, such as in Wyoming and
California, and also in Egypt, Kenya, Botswana, Tibet,
Venezuela and Turkey. Crude trona ore from Wyoming is
typically between about 80% and about 90% trona, with the
remaining components including shortite, quartz, dolomite,
mudstone, oil shale. kerogen, mica, nahcolite and clay
minerals.
The glass and paper making industries generally require
soda ash produced from trona having a purity of 99% or
more. In order to obtain such a high purity, wet beneficiation
processes have been used. Such processes generally involve
crushing the crude trona. solubilizing the trona, treating the 35
solution to remove insolubles and organic matter, crystallizing
the trona, and drying the trona which may subsequently
be calcined to produce soda ash. Alternatively, the
crude trona can be calcined to yield crude sodium carbonate,
which is then solubilized. treated to remove impurities, 40
crystallized and dried to produce sodium carbonate monohydrate.
Not all industries which use trona require such a highly
purified form of trona. For example, certain grades of glass
can be produced utilizing trona having less than 97% purity. 45
For this purpose, U.S. Pat. No. 4,341,744 discloses a dry
beneficiation process which is less complex and less expensive
than the above-described wet beneficiation process.
Such a dry beneficiation process generally includes crushing
the crude trona, classifying the trona by particle size, elec- 50
trostatically separating certain impurities, and optionally
magnetically separating other impurities. Such a process can
yield trona having up to about 95% to 97% purity. depending
on the quantity and type of impurities present in the crude
trona ore.
There are uses for trona, for example, in certain applications
in the glass industry, requiring a purity of at least 97%,
yet not needing a purity over 99%. The known dry beneficiation
processes typically do not consistently produce such
a purity. Consequently, these industries generally use trona 60
purified by the more expensive and complex wet beneficiation
processes.
Accordingly. it is an object of the present invention to
provide a dry process for the beneficiation of saline minerals
and in particular. trona. resulting in higher purities than 65
existing dry beneficiation processes and which is simpler
and less expensive than known wet beneficiation processes.
This is a continuation of application Ser. No. 08/066,871,
filed May 25, 1993. now U.S. Pat. No. 5.470.554.
FIELD OF THE INVENTION
The present invention relates generally to the beneficiation
of saline minerals and, more specifically, trona. The
invention further relates to a dry process for recovering
saline minerals from an ore containing saline minerals and
impurities.
5,651,465
3 4
ties are removed from the stream by density separation. In
both scavenging and cleaning passes, the feed stream into
those passes can undergo further size reduction, if desired,
for example, to achieve higher liberation.
With regard to the beneficiation of trona, which has a
density of 2.14, impurities that are removed during the
density separation step of the present invention include
shortite, having a density of 2.6. dolomite, having a density
of 2.8-2.9 and pyrite, having a density of 5.0. Each of these
is separable from the trona ore because of differences in
density from trona. By practice of the present invention, of
the total amount of shortite, dolomite, pyrite and, if present,
potentially valuable heavy minerals in the trona ore, the
density separation step can remove at least about 10 wt. %
and more preferably, about 50 wt. % and most preferably,
about 90 wt. % of the heavy impurity.
In an alternative embodiment, impurities removed during
the density separation process can be recovered as a product
for commercial use. For example, in the beneficiation of
trona, the impurities removed during the air tabling step can
comprise as much as 90% shortite. Such shortite may be
acceptable, for example, for certain applications in the glass
industry. The acceptability of the shortite in the glass industry
will depend upon the consistency and the relative lack of
25 iron in the product. In addition, for some trona deposits,
potentially valuable heavy minerals may be present. Such
minerals can be separated in the method and recovered.
The present invention further includes removing a second
portion of impurities by an electrostatic separation method.
Electrostatic separation methods are based on subjecting the
ore to conditions such that materials of different electrical
conductivities separate from each other. The electrostatic
separation of the present invention can be accomplished by
any conventional electrostatic separation technique. U.S.
Pat. No. 4,341,744 discloses standard electrostatic separation
processes suitable for use in the present invention in col.
4, line 62 through col. 6, line 32, which is incorporated
herein by reference in its entirety. As discussed in the
above-identified patent, saline mineral ore particles are first
differentially electrified and then separated into a recovered
stream from an impurity stream by various electrostatic
separation processes.
As noted above for the density separation step, the impurity
stream from the rougher pass of an electrostatic separation
process can go through a scavenger step to improve
the overall recovery. The scavenger step recovers a saline
mineral-containing portion of the impurity stream from the
rougher pass through electrostatic separation and combines
50 it with the above-described recovered stream to increase the
overall yield of the electrostatic separation step or otherwise
cycles it to other steps in the process. Furthermore, the
recovered stream from the rougher pass of the electrostatic
separation can go through one or more electrostatic cleaning
steps to further remove impurities from the recovered stream
and improve the purity of the final product.
For example, electrostatic separation can be used to
separate trona from impurities having a higher electrical
conductivity, such as shale, mudstone or pyrite. It should be
appreciated. however, that electrostatic separation could also
be used to separate impurities that have a lower electrical
conductivity than the saline mineral being recovered. By
practice of the present invention, utilizing electrostatic separation
can remove at least about 10 wt. %, more preferably,
about 50 wt. %, and most preferably, about 90 wt. % of the
more conductive mineral impurities from the material being
treated by electrostatic separation.
between about 80 and about 90 wt. % trona. The remaining
10 to 20 wt. % of the ore in the Green River Formation
sample comprised impurities including shortite (1-5 wt. %)
and the bulk of the remainder comprises shale consisting
predominantly of dolomite, clay, quartz and kerogen, and 5
traces of other impurities. Other samples of trona ore can
include different percentages of trona and impurities, as well
as include other impurities.
The present process includes removing a first portion of
impurities from an ore containing saline minerals by a 10
density separation method. Density separation methods are
based on subjecting an ore to conditions such that materials
of different densities physically separate from each other.
Thereby, certain impurities having a different density than
the desired saline mineral can be separated. The density 15
separation step of the present invention is most preferably a
dry process. however, wet density separation processes, such
as heavy media separation, can be used as well. In dry
density separation processes, the need for processing in a
saturated brine solution, solidlbrine separation, and drying 20
of the product is eliminated. Consequently, the process
according to the present invention is much cheaper and less
complex. Any known density separation technique could be
used for this step of the present invention, including air
tabling or dry jigging.
As discussed above, density separation is conducted by
subjecting an ore to conditions such that materials of different
densities separate from each other. The mineral stream
having materials of varying densities is then separated by a
first or rougher pass into a denser and a lighter stream, or 30
into more than two streams of varying densities. Typically,
in the case of beneficiating trona, trona is recovered in the
lighter stream. The purity of a saline mineral recovered from
density separation can be increased by reducing the weight
recovery of the recovered stream from the feed stream. At 35
lower weight recoveries, the recovered stream will have a
higher purity, but the rougher stage process will also have a
reduced yield because more of the desired saline mineral
will report to the impurity stream. Such a "high purity"
process may be beneficial in that it requires less subsequent 40
processing (e.g., separation) of the ore and, in addition, may
be of higher value because it can be used in other applications
where high purity saline minerals are required.
In the case of beneficiating trona. for example, the weight 45
recovery (weight of trona recovered/weight of trona in the
feed stream) from the density separation step is between
about 65% and about 95%. More preferably, the weight
recovery is between about 70% and about 90% and, most
preferably, the weight recovery is about 80%.
In an alternative embodiment, the impurity stream from
density separation can go through one or more scavenger
density separation step(s) to recover additional trona to
improve the overall recovery. The scavenger separation is
similar to the above-described density separation step. The 55
scavenger step recovers a portion of the impurity stream
from the rougher pass having the saline mineral in it and
combines that portion with the above-described recovered
stream to increase the overall yield from density separation
or recycles it to other steps in the process, with or without 60
further size reduction.
In a further alternative embodiment, the recovered stream
from the rougher pass density separation can go through one
or more cleaning density separation steps to further remove
impurities from the recovered stream and improve the purity 65
of the final product. The cleaning step is similar to the
above-described density separation process in that impuri5,651,465
5 6
fraction, the higher the efficiency of removal of impurities.
On the other hand, a larger number of fractions will increase
the efficiency, but may increase the cost of the overall
process. The use of between 3 and 10 fractions has been
5 found to be acceptable. Preferably, the number of fractions
is between 4 and 10 and, more preferably, the number of
fractions is 8. Any conventional sizing technique can be used
for the present process, including screening or air classification.
For dividing into 8 fractions. the fractions typically
10 have the following particle size ranges: 6 to 8 mesh; 8 to 10
mesh; 10 to 14 mesh; 14 to 20 mesh; 20 to 28 mesh; 28 to
35 mesh; 35 to 48 mesh; 48 to 65 mesh (fyler mesh).
In yet another embodiment of the present invention, the
ore is dried prior to the separation processes set forth above.
15 The drying step removes surface moisture from the ore to
better enable the ore to be separated. Drying can be accomplished
by any conventional mineral drying technique,
including rotary kiln, fluid bed or air drying. The ore can be
dried to less than about 2%, and preferably less than about
20 1% surface moisture content. During the drying process, it
is preferred that the saline mineral is not raised to such a
temperature for such a period of time that is it calcined. In
the case of trona, the drying temperature should remain
below about 40 degrees centigrade to avoid calcination.
In still another embodiment of the present invention, a
de-dusting step is added to the basic beneficiation process to
remove fines before the electrostatic and magnetic separation
steps. De-dusting can be particularly important before
electrostatic separation because the dust can otherwise inter-
30 fere with effective electrostatic separation. Such a
de-dusting step can be conducted before, during or after one
or more of the crushing, sizing and/or density separation
steps. The fines produced during the processing of trona are
relatively high purity trona and are useful in several indus-
35 trial applications. For example, trona recovered by
de-dusting can have a purity of greater than about 94%,
preferably greater than about 96% and more preferably
greater than about 98%. Fines can be collected in de-dusting
steps by use of a baghouse, or other conventional filtering
40 device, and sold as purified trona without further processing.
The present invention provides a process for the separation
of saline minerals from an ore utilizing a dry beneficiation
technique, resulting in a high purity product, typi-
45 cally greater than 85% purity, produced at low cost
compared to wet beneficiation processes. Utilizing the
above-described process, trona having about 98.8% purity
from an ore containing 90% trona has been obtained, compared
to less than about 97% purity for the prior art dry
50 beneficiation processes. The purity of recovered product can
be greater than about 97%, preferably greater than about
97.5%, and more preferably greater than about 98%. In
addition, by utilizing selective mining techniques and lower
weight recoveries for the separation steps, higher purities
55 can be obtained.
Utilizing the process of the present invention, recoveries
of greater than about 55% can be obtained. More preferably,
recoveries are greater than about 65% and. most preferably,
greater than about 75%. In the case of trona, the resulting
60 trona product can be used in many applications. especially
those requiring a purity of about 97.5% or greater, such as
in certain areas of the glass industry.
It has been found that the above-identified process for
beneficiating trona is also particularly adaptable for use in
65 the production of caustic for use in alumina production. By
transporting beneficiated and calcined trona ore to alumina
processing facilities and producing caustic from the benefi-
The present process further includes a magnetic separation
step which subjects the ore to conditions such that
materials of different magnetic susceptibilities separate from
each other into a recovered stream and an impurity stream.
The magnetic separation step can be accomplished by any
conventional technique. such as induced roll, cross-belt, or
high intensity rare earth magnetic separation methods.
Preferably. induced roll is used in the present invention for
the finer fractions and high intensity rare earth magnets are
used for the coarser fractions. With regard to the beneficiation
of trona. typical impurities that can be removed during
the magnetic separation step include shale which has a
higher magnetic susceptibility than trona. By practice of the
present invention, the use of an induced roll magnetic
separation technique can remove at least about 5 wt. %,
more preferably, about 50 wt. %, and most preferably about
90 wt. % of the shale from the material being treated by
magnetic separation.
As noted above for the density and electrostatic separation
steps, the impurity stream from the rougher pass of the
magnetic separation process can go through one or more
scavenger steps to improve the overall recovery. The scavenger
step recovers a portion of the impurity stream from the
rougher pass through magnetic separation and combines it
with the above-described recovered stream or recycles it to 25
the process with or without further size reduction to increase
the overall yield of the magnetic separation step.
Furthermore, the recovered stream from magnetic separation
can go through one or more magnetic cleaning steps to
further remove impurities from the recovered stream and
improve the purity of the final product.
It should be appreciated that the above-identified process
steps could be performed in any order. Preferably, however.
the density separation is performed first. followed by electrostatic
separation and finally magnetic separation.
In a further embodiment of the present invention, the
saline mineral-containing ore can be crushed to achieve
liberation of impurities prior to the separation steps. The
crushing step of the present invention can be accomplished
by any conventional technique, including impact crushing
(e.g., cage or hammer mills), jaw crushing. roll crushing,
cone crushing. autogenous crushing or semi-autogenous
crushing. Autogenous and semi-autogenous crushing are
particularly beneficial because the coarse particles of ore
partially act as the crushing medium. thus requiring less cost
in obtaining grinding media. Moreover. because saline minerals
are typically soft. these methods are suitable for use in
the present process. In addition, these two crushing methods
allow for the continuous removal of crushed material and
high grade potentially saleable dust.
In general. crushing to smaller particle size achieves
better liberation of impurities and thus, improved recovery.
However, if the particle size after crushing is too fine, there
may be adverse effects upon subsequent separation steps. In
addition, over-crushing is not needed for many applications
of the present invention and merely increases the costs
associated with the crushing step. It has been found that
acceptable liberation for the present process can be achieved
by crushing the ore to at least about 6 mesh. Preferably, the
particle size range after crushing is from about 6 to about
100 mesh and, more preferably, from about 6 to about 65
mesh.
In another embodiment of the present invention. the ore is
sized into size fractions prior to the separation steps. Each
size fraction is subsequently processed separately. In
general. the narrower the range of particle size within a
5,651,465
7
ciated trona. the total cost for caustic can be significantly
below that of caustic currently used in the alumina industry.
For this application. the trona-containing ore is beneficiated
and the resulting beneficiated trona is calcined to produce
soda ash (Na2C03). The soda ash is then converted to caustic
soda by conventional processes at an alumina plant and can
then be used in conventional alumina processing. For
example. the Bayer process can be used in which caustic
soda is mixed with bauxite to solubilize the aluminum
hydroxide in the bauxite to produce a sodium aluminate
solution. Alumina hydrate can be precipitated from the
solution and calcined to remove water therefrom.
The foregoing description of the present invention has
been presented for purposes of illustration and description.
Furthermore. the description is not intended to limit the
invention to the form disclosed herein. Consequently, variations
and modifications commensurate with the above
teachings, and the skill or knowledge of the relevant art. are
within the scope of the present invention. The embodiment
described hereinabove is further intended to explain the best
mode known for practicing the invention and to enable
others skilled in the art to utilize the invention in such. or
other. embodiments and with various modifications required
by the particular applications or uses of the present invention.
It is intended that the appended claims be construed to
include alternative embodiments to the extent permitted by
the prior art.
EXAMPLES 1-8
Eight samples of trona-containing ore from Bed 17 of the
Green River Formation in Wyoming were beneficiated in
8
accordance with the present invention. Each of the samples
was crushed to -10 mesh on a roll crusher. The samples were
allowed to air dry until they attained a constant weight
(about 24 hours). The samples were subsequently screened
5 at 20 mesh. 35 mesh, 65 mesh and 150 mesh Tyler. Each of
the four 150 plus size fractions was then subjected to
electrostatic separation to generate a conductive and nonconductive
stream. The non-conductive stream resulting
from the electrostatic separation regime for each of the size
10 fractions was subjected to high intensity magnetic separation
to generate a magnetic and non-magnetic stream. The resulting
non-conductive/non-magnetic streams from each of the
size fractions were then subjected to a density separation
step. A heavy liquid separation was used for density sepa-
15 ration in these examples. The heavy liquid used was a
mixture of acetylene tetrabromide and kerosene. Since the
saline mineral being beneficiated was trona, having a specific
gravity of 2.14; the major impurity was shortite, having
a specific gravity of 2.6; and other impurities having a
20 specific gravity lighter than 2.0 were present, density separations
were made at specific gravities of 2.0 and 2.3 to
generate a 2.0x2.3 fraction which is the trona fraction.
The data generated from the foregoing beneficiation pro-
25 cesses is shown in Tables 1-8. As can be seen from the
Tables. the purity of trona recovered ranged from 95.3 in
Example 2 to 98.8 in Example 3 (shown as soluble % in
2.0x2.3 S.G. separation). In addition, the effectiveness of the
density separation in improving trona purity can be seen by
30 comparing the Soluble % in the "Plus 65 mesh trona" line
(before density separation) with the Soluble % in the ''2.0x
2.3 S.G." line (after density separation).
TABLE 1
Electrostatic and Magnetic Separation of Trona-Containing Waste Rock; Sample 1
Weight Percent Assay
Beneficiated Insoluble Soluble
Fraction Fraction Sample Product % Distr. % Distr.
10 x 20 mesh
conductive stream 86.4 41.7 93.9 44.6 6.2 21.2
magnetic stream 2.0 1.0 67.3 0.7 32.7 2.6
non-conductive! 11.6 5.6 24.6 69.5 4.4 30.5 14.0
non-magnetic
stream
Total 100.0 48.3 90.5 49.8 9.5 37.7
20 x 35 mesh
conductive stream 56.9 12.1 91.9 12.6 8.1 9.0
magnetic stream 9.5 2.0 83.6 1.9 16.4 2.7
non-conductive! 33.6 7.1 31.3 83.2 6.8 16.8 9.8
non-magnetic
stream
Total 100.0 21.2 88.2 21.3 11.8 20.5
35 x 65 mesh
conductive stream 28.6 3.9 91.5 4.1 8.5 2.7
magnetic stream 19.1 2.6 87.0 2.6 13.0 2.8
non-conductive! 52.2 7.1 31.3 85.3 6.9 14.7 8.6
non-magnetic
stream
Total 100.0 13.6 87.4 13.6 12.6 14.1
65 x 150 mesh
conductive stream 50.8 3.7 87.8 3.7 12.2 3.7
magnetic stream 8.9 0.7 82.7 0.6 17.3 0.9
non-conductive! 40.3 2.9 12.9 77.4 2.6 22.6 5.4
non-magnetic
5,651,465
9 10
TABLE I-continued
Electrostatic and Magnetic Separation of Trona-Containing Waste Rock; Sample 1
Weight Percent Assay
Beneficiated Insoluble Soluble
Fraction Fraction Sample Product % Distr. % Distr.
stream
Total 100.0 7.3 83.2 6.9 16.8 10.0
Minus 150 mesh 9.6 77.4 8.4 22.6 17.7
Plus 65 mesh trona 19.9 80.1 18.1 19.9 32.4
'frona Prod., Calc. 22.8 100.0 79.7 20.7 20.3 37.8
'frona + minus 32.4 79.0 29.2 21.0 55.5
150 Calc.
Sample Calc. 100.0 87.8 100.0 12.2 100.0
Heavy Liquid DellSity Separation of Plus 65 Mesh Non-MagneticlNon-Conductive Sample 1
<2.0 S.G. 0.2 0.0
2.0 x 2.3 S.G. 19.0 3.8 3.4 0.1 96.6 29.8
>2.3 S.G. 80.8 16.1 98.3 18.0 1.7 2.5
Total 100.0 19.9 80.1 18.1 19.9 32.4
TABLE 2
Electrostatic and Magnetic Separation of Trona-Containing Waste Rock: Sample 2
Weight Percent Assay
Beneficiated Insoluble Soluble
Fraction Fraction Sample Product % Distr. % Distr.
0.7
0.9
6.0
1.7
1.8
8.7
49.1
6.9
56.0
7.6
17.3
56.0
62.0
79.3
12.2
39
2.0
10.4
46.6
8.3
1.4
36.9
42.5
56.4
68.4
67.3
64.5
33.3
2.2 17.1
1.8 25.7
3.0 58.0
5.0 18.7
2.1 37.1
5.2 53.3
1.7 95.3
16.1 7.7
17.8 68.4
7.1
9.2
17.8
20.8
30.0
22.5
12.8 17.2
3.2 30.7
6.5 52.3
48.9 39.6
12.4 40.4
409 12.3
2.0 31.9
6.0 80.9
4.7
92.3
31.6
57.5
43.6
31.6
32.7
35.5
66.7
59.6
82.9
74.3
42.0
82.8
69.3
47.7
81.3
62.9
46.7
60.4
87.7
68.1
19.1
11.2
21.6
17.7
49.4
100.0
1.6
1.5
4.2
3.7
2.0
6.6
9.1
2.7
8.1
7.3
12.5
33.4
37.6
SO.l
20.0
12.3
27.6
1.8
18.6
47.9
22.0
20.1
57.9
45.8
13.5
40.7
16.3
30.0
15.9
54.1
57.6
3.7
38.7
100.0
100.0
100.0
100.0
10 x 20 mesh
conductive stream
magnetic stream
non-conductivel
non-magnetic
stream
Total
20 x 35 mesh
conductive stream
magnetic stream
non-conductivel
non-magnetic
stream
Total
35 x 65 mesh
conductive stream
magnetic stream
non-conductivel
non-magnetic
stream
Total
65 x ISO mesh
conductive stream
magnetic stream
non-conductive/
non-magnetic
stream
Total
Minus 150 mesh
Plus 65 mesh trona
'frona Prod., Calc.
Trona +minus
150 Calc.
Sample Calc. 100.0 59.2 100.01 40.9 100.0
Heavy Liquid DellSity Separation of Plus 65 Mesh Non-MagneticlNon-Conductive Sample 2
<2.0 S.G. 6.0 2.0
2.0 x 2.3 S.G. 63.0 21.0
>2.3 S.G. 31.0 10.3
Total 100.0 33.4
5,651,465
11
TABLE 3
Electrostatic and Magnetic Separation of Trona-Containing Waste Rock: Sample 3
12
Weight Percent
Beneficiated
Assay
Insoluble Soluble
Fraction Fraction Sample Product % Distr. % Distr.
10 x 20 mesh
conductive stream 26.1 13.2 30.1 50.8 69.9 10.0
magnetic stream 4.4 2.2 4.6 1.3 95.4 2.3
non-conductive! 69.5 35.2 58.8 2.4 10.8 97.6 37.3
non-magnetic
stream
Total 100.0 50.6 9.7 63.0 90.3 49.6
20 x 35 mesh
conductive stream 24.9 4.0 25.0 12.7 75.0 3.2
magnetic stream 5.8 0.9 5.6 0.7 94.4 1.0
non-conductive! 69.3 11.1 18.5 3.0 4.3 97.0 11.7
non-magnetic
stream
Total 100.0 16.0 8.6 17.7 91.4 15.9
35 x 65 mesh
conductive stream 12.3 1.3 21.3 3.7 78.7 1.1
magnetic stream 4.0 0.4 6.6 0.4 93.4 0.4
non-conductive! 83.7 9.1 15.2 4.1 4.8 95.9 9.5
non-magnetic
stream
Total 100.0 10.9 6.3 8.8 93.7 11.1
65 x 150 mesh
conductive stream 27.5 1.8 8.2 1.9 91.8 1.8
magnetic stream 3.9 0.3 4.4 0.1 95.6 0.3
non-conductive! 69.7 4.4 7.4 3.6 2.0 96.4 4.6
non-magnetic
stream
Total 100.0 6.5 4.9 4.0 95.1 6.7
Minus 150 mesh 16.0 3.2 6.6 96.8 16.8
Plus 65 mesh trona 55.4 2.8 19.8 97.2 58.4
Trona Prod., Calc. 59.8 100.0 2.9 21.9 97.1 63.1
Trona + minus 75.9 2.9 28.4 97.1 79.9
150 Calc.
Sample Calc. 100.0 7.8 100 92.2 100
Heavy Liquid Density Separation of Plus 65 Mesh Non-MagneticlNon-Conductive Sample 3
<2.0 S.G. 0.2 0.1
2.0 x 2.3 S.G. 96.1 53.2 1.2 8.2 98.8 57.1
>2.3 S.G. 3.7 2.1 44.5 11.7 55.5 1.4
Total 100.0 55.4 2.8 19.8 97.2 58.4
TABLE 4
Electrostatic and Magnetic Separation of Trona-Containing Waste Rock; Sample 4
Weight Percent Assay
Beneficiated Insoluble Soluble
Fraction Fraction Sample Product % Distr. % Distr.
10 x 20 mesh
conductive stream 11.7 6.4 11.3 22.3 88.7 5.9
magnetic stream 6.3 3.5 3.0 3.2 97.0 3.5
non-conductive! 82.0 45.0 68.3 1.9 26.3 98.1 45.6
non-magnetic
stream
Total 100.0 54.8 3.1 51.8 96.9 54.9
20 x 35 mesh
conductive stream 15.4 2.2 14.3 9.5 85.7 1.9
magnetic stream 10.8 1.5 5.4 2.5 94.6 1.5
non-conductive! 73.8 10.3 15.7 2.6 8.3 97.4 10.4
non-magnetic
stream
Total 100.0 14.0 4.7 20.3 95.3 13.8
35 x 65 mesh
conductive stream 18.7 1.4 11.1 4.9 88.9 1.3
magnetic stream 2.1 0.2 10.5 0.5 89.5 0.1
non-conductive! 79.2 6.0 9.2 3.8 7.1 96.2 6.0
5,651,465
13
TABLE 4-continued
Electrostatic and Magnetic Separation of Trona-Containing Waste Rock; Sample 4
14
Weight Percent
Beneficiated
Assay
Insoluble Soluble
Fraction Fraction Sample Product % Distr. % Distr.
non-magnetic
stream
Total 100.0 7.6 5.3 12.5 94.7 7.5
65 x 150 mesh
conductive stream 17.9 1.1 7.0 2.3 93.0 1.0
magnetic stream 4.4 0.3 2.5 0.2 97.5 0.3
non-conductivel 77.7 4.6 6.9 3.0 4.2 97.0 4.6
non-magnetic
stream
Total 100.0 5.9 3.7 6.7 96.3 5.8
Minus 150 mesh 17.7 1.6 8.7 99.4 18.0
Plus 65 mesh trona 61.3 2.2 41.7 97.7 66.6
Trona Prod., Calc. 65.9 100.0 2.3 45.9 97.8 78.7
Trona + minus 83.6 2.1 54.6 97.9 84.6
150 Calc.
Sample Calc. 100.0 3.2 100.0 96.8 100.0
Heavy Liquid Density Separation of Plus 65 Mesh Non-MagneticlNon-Conductive Sample 4
<2.0 S.G. 0.4 0.0
2.0 x 2.3 S.G. 98.6 60.5 2.0 37.3 98.0 61.2
>2.3 S.G. 1.0 0.6 23.3 4.4 76.7 5.3
Total 100.0 61.3 2.2 41.7 97.7 66.6
TABLES
Electrostatic and Magnetic Separation of Trona-Containing Waste Rock: Sample 5
Weight Percent Assay
Beneficiated _ ...Ins=o",l""ub",l",e_ Soluble
Fraction Fraction Sample Product % Distr. % Distr.
10 X 20 mesh
conductive stream 23.0 10.9 37.8 48.0 62.2 7.4
magnetic stream 5.2 2.5 3.8 1.1 96.2 2.6
non-conductivel 71.9 34.2 56.2 3.0 11.9 97.0 36.3
non-magnetic
stream
Total 100.0 47.6 11.0 61.0 89.0 46.4
20 x 35 mesh
conductive stream 21.3 3.7 25.7 11.0 74.3 3.0
magnetic stream 10.2 1.8 5.2 1.1 94.8 1.8
non-conductivel 68.5 11.9 19.5 3.5 4.8 96.5 12.5
non-magnetic
stream
Total 100.0 17.3 8.4 16.9 91.6 17.4
35 x 65 mesh
conductive stream 19.8 2.2 17.0 4.4 83.0 2.0
magnetic stream 5.9 0.7 7.4 0.6 92.6 0.7
non-conductivel 74.3 8.4 13.8 4.6 4.5 95.4 8.7
non-magnetic
stream
Total 100.0 11.3 7.2 9.5 92.8 11.4
65 x 150 mesh
conductive stream 19.7 1.6 11.0 2.1 89.0 1.6
magnetic stream 3.4 0.3 3.8 0.1 96.2 0.3
non-conductivel 76.8 6.4 10.5 4.4 3.3 95.6 6.7
non-magnetic
stream
Total 100.0 8.3 5.7 5.5 94.3 8.6
Minus 150 mesh 15.5 4.0 7.2 96.0 16.3
Plus 65 mesh trona 54.5 3.4 21.2 96.5 64.3
Trona Prod., Calc. 60.8 100.0 3.5 24.5 96.6 72.0
Trona + minus 76.3 3.6 31.7 96.4 80.5
150 Calc.
Sample Calc. 100 8.6 100 91.4 100
Heavy Liquid Density Separation of Plus 65 Mesh Non-MagneticlNon-Conductive Sample 5
<2.0 S.G. 0.3 0.2
5,651,465
15
TABLE 5-continued
Electrostatic and Magnetic Separation of Trona-Containing Waste Rock; Sample 5
16
Weight Percent
Beneficiated Insoluble
Assay
Soluble
Fraction Fraction Sample Product % Distr. % Distr.
2.0 x 2.3 S.G. 92.6 50.4 2.5 14.6 97.5 53.8
>2.3 S.G. 7.1 3.9 20.2 9.1 79.8 10.5
Total 100.0 54.5 3.4 21.2 96.5 64.3
TABLE 6
Electrostatic and Magnetic Separation of Trona-Containing Waste Rock; Sample 6
Weight Percent Assay
Beneficiated Insoluble Soluble
Fraction Fraction Sample Product % Distr. % Distr.
10 x 20 mesh
conductive stream 28.3 14.1 18.0 47.7 82.0 12.2
magnetic stream 4.4 2.2 2.8 1.1 97.2 2.2
non-conductive! 67.3 33.4 57.3 2.1 13.2 97.9 34.5
non-magnetic
stream
Total 100.0 49.7 6.6 62.0 93.4 49.0
20 x 35 mesh
conductive stream 17.5 2.7 21.4 10.8 78.6 2.2
magnetic stream 6.7 1.0 3.8 0.7 96.2 1.0
non-conductive! 75.8 11.6 19.9 3.0 ·6.5 97.0 11.9
non-magnetic
stream
Total 100.0 15.3 6.3 18.1 93.7 15.1
35 x 65 mesh
conductive stream 13.0 1.1 16.2 3.5 83.8 1.0
magnetic stream 6.0 0.5 6.7 0.7 93.3 0.5
non-conductive! 81.0 7.1 12.3 2.8 3.8 97.2 7.3
non-magnetic
stream
Total 100.0 8.8 4.8 7.9 95.2 8.9
65 x 150 mesh
conductive stream 16.5 1.3 6.6 1.6 93.4 1.3
magnetic stream 4.2 0.3 3.6 0.2 96.4 0.3
non-conductive! 79.3 6.1 10.5 2.2 2.5 97.8 6.3
IlOn~magnetic
stream
Total 100.0 7.7 3.0 4.3 97.0 7.9
Minus 150 mesh 18.5 2.2 7.7 97.8 19.1
Plus 65 mesh trona 52.1 2.4 23.5 97.6 60.1
Trona Prod., Calc. 58.3 100.0 2.4 26.0 97.6 71.3
Trona + minus 76.8 2.3 33.7 97.7 79.2
150 Calc.
Sample Calc. 100.0 5.3 100.0 94.7 100.0
Heavy Liquid Density Separation of Plus 65 Mesh Non-MagneticlNon-Conductive Sample 6
<2.0 S.G. 0.4 0.2
2.0 x 2.3 S.G. 98.8 51.5 2.0 19.4 98.0 53.3
>2.3 S.G. 0.8 0.4 52.5 4.1 47.5 6.8
Total 100.0 52.1 2.4 23.5 97.6 60.1
5,651,465
17
TABLE 7
Electrostatic and Magnetic Separation of Trona-Containing Waste Rock: Sample 7
18
Weight Percent
Beneficiated
Assay
Insoluble Soluble
Fraction Fraction Sample Product % Distr. % Distr.
10 x 20 mesh
conductive stream 0.0 0.0 0.0 0.0
magnetic stream 15.8 5.0 34.1 16.5 65.9 3.6
non-conductive/ 84.2 26.3 34.6 9.7 24.9 90.3 26.5
non-magnetic
stream
Total 100.0 31.3 13.6 41.3 86.4 30.2
20 x 35 mesh
conductive stream 0.0 0.0 0.0 0.0
magnetic stream 8.0 1.7 29.3 4.8 70.7 1.3
non-conductive! 92.0 19.3 25.3 7.7 14.5 92.3 19.9
non-magnetic
stream
Total 100.0 21.0 9.4 19.2 90.6 21.2
35 x 65 mesh
conductive stream 0.0 0.0 0.0 0.0
magnetic stream 11.4 2.2 23.7 5.1 76.3 1.9
non-conductive! 88.6 17.0 22.3 6.4 10.6 93.6 17.8
non-magnetic
stream
Total 100.0 19.2 8.4 15.7 91.6 19.6
65 x 150 mesh
conductive stream 0.0 0.0 0.0 0.0
magnetic stream 6.5 0.9 21.1 1.9 78.9 0.8
non-conductive! 93.5 13.6 17.8 7.6 10.0 92.4 14.0
non-magnetic
stream
Total 100.0 14.5 8.5 12.0 91.5 14.8
Minus 150 mesh 14.0 8.7 11.8 91.3 14.2
Plus 65 mesh trona 62.7 8.2 49.9 91.9 78.1
Trona Prod., Calc. 76.3 100.0 8.1 60.0 91.8 77.5
Trona + minus 90.2 8.2 71.8 91.8 92.4
150 Calc.
Sample Calc. 100.0 10.3 100.0 89.7 100.0
Heavy Liquid Density Separation of Plus 65 Mesh Non-MagneticlNon Conductive Sample 7
<2.0 S.G. 0.2 0.1
2.0 x 2.3 S.G. 93.0 58.3 4.2 23.8 95.8 62.2
>2.3 S.G. 6.8 4.3 63.0 26.1 37.0 15.9
'Ibtal 100.0 62.7 8.2 499 91.9 78.1
TABLE 8
Electrostatic and Magnetic Separation of Trona-Containing Waste Rock: Sample 8
Weight Percent Assay
Beneficiated Insoluble Soluble
Fraction Fraction Sample Product % Distr. % Distr.
10 x 20 mesh
conductive stream 18.8 6.2 35.0 23.6 65.0 4.5
magnetic stream 1.3 0.4 28.7 1.4 71.3 0.4
non-conductive/ 79.9 26.5 40.9 4.4 12.6 95.6 27.9
non-magnetic
stream
Total 100.0 33.2 10.5 37.6 89.5 32.7
20 x 35 mesh
conductive stream 13.6 3.0 45.7 15.0 54.3 1.8
magnetic stream 2.1 0.5 40.9 2.1 59.1 0.3
non-conductive/ 84.3 189 29.2 6.3 12.9 93.7 19.5
non-magnetic
stream
Total 100.0 22.4 12.4 30.0 87.6 21.6
35 x 65 mesh
conductive stream 10.0 1.1 50.2 5.9 49.8 0.6
magnetic stream 3.2 0.3 48.9 1.8 51.1 0.2
non-conductive! 86.7 9.3 14.4 6.9 7.0 93.1 9.6
5,651,465
19 20
TABLE 8-continued
Electrostatic and Magnetic Separation of Trona-Containing Waste Rock; Sample 8
Weight Percent Assay
Beneficiated Insoluble Soluble
Fraction Fraction Sample Product % Distr. % Distr.
10.4
1.3
0.2
10.6
57.3
57.0
12.1
23.2
57.0
67.6
90.8
87.4
93.3
96.1
94.5
94.8
95.1
3.6 77.9
1.0 68.0
3.9 96.4
14.7
11.5 98.0
8.5
9.2
32.5
36.4
45.6
32.5 94.5
2.0
6.7
3.9
5.5
5.2
4.9
5.5
22.1
32.0
3.6
12.6
15.4
100.0
10.8
1.5
0.3
10.0
11.8
21.9
54.7
64.7
86.6
12.7
2.5
84.8
100.0
100.0
mn-magnetic
stream
Total
65 x 150 mesh
conductive stream
magnetic stream
mn-conductivel
mn-magnetic
stream
Total
Minus 150 mesh
Plus 65 mesh trona
Trona Prod., Calc.
Trona + minus
150 Calc.
Sample Calc. 100.0 9.2 100.0 90.8 100.0
Heavy Liquid Density Separation of Plus 65 Mesh Non-MagneticlNon-Conductive Sample 8
<2.0 S.G. 0.3 0.2
2.0 x 2.3 S.G. 97.0 53.1
>2.3 S.G. 2.7 1.5
Total 100.0 54.7
The non-conductors and middlings from each of the
above-referenced electrostatic separation processes were
individually magnetically separated utilizing an induced roll
magnetic separator. The conductors from each of the electrostatic
separation processes were not subjected to magnetic
separation. The magnetic separation process separated each
incoming sample into two fractions: magnetic and nonmagnetic.
The weights and weight percentages of each
magnetically separated fraction are listed in the three columns
of data in Table 9, as described above.
The cumulative products of the entire recovery process
are represented by the data in the third column at the end of
Table 9. The data represents the weight percentage of
non-magnetic, non-conductor material recovered from the
combined light and heavy density fractions and from the
ultra-heavy density fraction. As can be seen from the Table,
91.3% of the original sample was recovered as nonmagnetic,
non-conductive material. The trona purity of the
recovered material was determined. The trona product from
the lights plus heavies had a purity of 98.2%. The trona
product from the ultra-heavies, which contained the shortite,
had a purity of 88.9%. Comparison of these purities illustrates
the benefit of removing shortite.
processes divided the sample into three electrostatic frac-
30 tions: conductors, middlings, and non-conductors. The
respective weights and weight percentages of each electrostatic
fraction are listed in the three columns of data in Table
9, as noted above.
EXAMPLE 9
An ore sample containing trona, recovered from Bed 17
of the Green River Formation in Wyoming, was beneficiated
using the process described below and the results are represented
by the data in Table 9. The ore was a commercially
available trona-containing material identified as T-50, avail- 35
able from Solvay Minerals S.A., Green River, Wyo. The
T-50 material has a trona purity of about 95% and a size
range of 20x150 mesh Tyler.
The ore sample was first classified using a screening
process to divide the ore sample into three size fractions: 40
+35 mesh, 35x65 mesh, and -65 mesh. After screening, the
+35 mesh and 35x65 mesh fractions were each separated on
an air table into three density fractions: ultra-heavy, heavy
and light.
After air tabling, each of the density fractions which were 45
air tabled, and the -65 mesh size fraction that was not air
tabled, were electrostatically separated by a high tension
separator. To improve trona recovery, as seen in Table 9, the
light and heavy density fractions from the +35 mesh size
fraction were combined and electrostatically separated 50
together. Similarly, the light and heavy density fractions
from the 35x65 mesh size fraction were electrostatically
separated together. Electrostatic separation was further performed
on the ultra-heavy fraction from the +35 mesh size
fraction, the ultra-heavy fraction from the 35x65 mesh size 55
fraction, and the -65 mesh size fraction that was not air
tabled. Each of the above-identified electrostatic separation
5,651,465
21 22
TABLE 9
Density, Electrostatic and Magnetic Separation of Trona Ore; Sample 9
Weight
(g, nnless)
otherwise Weight Percent Purity
Separation noted) Fraction' Sample" (% trona)
SCREENING
plus 35 mesh 362lb 36.8 36.8
35 x 65 mesh 482lb 49.0 49.0
minus 65 mesh 140lb 14.2 14.2
Total 984lb 100.0 100.0
AIR TABLE SEPAR1UIONS
plus 35 mesh
fit. Heavy 1605 4.2 1.5
Heavy 1814 4.7 1.7
Lights 34%0 91.1 33.5
Total 38379 100.00 36.8
35 x 65 mesh
fit. Heavy 800 2.4 1.2
Heavy 1603.5 4.7 2.3
Lights 31560 92.9 45.5
Total 33963.5 100.0 49.0
minus 65 mesh not air tabled
IDGH TENSION ELECTROSTI\TlC
SEPAR1UIONS (HT)
plus 35 mesh air table lights + heavies
Condo 190.8 7.4 2.6
Midd 230.5 8.9 3.1
Non-Cond. 2159.5 83.7 29.5
Total 2590.8 100.0 35.3
35 x 65 mesh air table lights + heavies
Condo 90.4 4.5 2.2
Midd 199.3 10.0 4.8
Non-Cond. 1709.5 85.5 40.9
Total 1999.2 100.0 47.8
plus 35 mesh air table ultra heavies
Condo 467.3 29.2 0.4
Midd 188.7 11.8 0.2
Non-Cond. 943 59.0 0.9
Total 1599 100.0 1.5
35 x 65 mesh air table ultra heavies
Condo 97 12.1 0.1
Midd 106.8 13.4 0.2
Non-Cond. 595 74.5 0.9
Total 798.8 100.0 1.2
minus 65 mesh
Condo 23.4 1.4 0.2
Midd %.9 6.0 0.9
Non-Cond. 1500.6 92.6 13.2
Total 1620.9 100.0 14.2
IDGH JNIENSITY MAGNETIC
SEPAR1UIONS (ill)
plus 35 mesh Non Condo from lights + heavies
IDMag. 22.6 1.0 0.31
IDNonMag. 2136.0 99.0 29.19
Total 2158.6 100.0 29.50
35 x 65 mesh Non Condo from lights + heavies
IDMag. 61.1 4.1 1.67
ID Non Mag. 1438.1 95.9 39.23
Total 1499.2 100.0 40.90
plus 35 mesh Non Condo from ultra heavies
IDMag. 11.2 1.2 0.01
ID Non Mag. 931.7 98.8 0.90
Total 942.9 100.0 0.91
35 x 65 mesh Non Condo from ultra heavies
IDMag. 53.1 8.9 0.08
ID Non Mag. 541.7 91.1 0.79
Total 594.8 100.0 0.86
minus 65 mesh Non Condo
IDMag. 59.9 3.5 0.46
ID Non Mag. 1649.0 96.5 12.71
Total 1708.9 100.0 13.17
5,651,465
23 24
TABLE 9-continued
Density. Electrostatic and Magnetic Separation of Trona Ore; Sample 9
Weight
(g, unless)
otherwise Weight Percent Purity
Separation noted) Fraction* Sample** (% trona)
plus 35 mesh HI Mid from lights + heavies
HI Mag. 15.6 7.8 0.25
HI Non Mag. 183.8 92.2 2.90
Total 199.4 100.0 3.15
35 x 65 mesh HI Mid from lights + heavies
HI Mag. 13.8 6.0 0.29
HI Non Mag. 216.9 94.0 4.48
Total 230.7 100.0 4.77
minus 65 mesh HI Mid
HI Mag. 11.8 12.2 0.02
HI Non Mag. 85.1 87.8 0.16
Total 96.9 100.0 0.18
plus 35 mesh HI Mid from ultra heavies
HI Mag. 7.6 4.0 om
HI Non Mag. 181.2 96.0 0.15
Total 188.8 100.0 0.15
35 x 65 mesh HI Mid from ultra heavies
HI Mag. 6.9 6.5 0.05
HI Non Mag. 100.0 93.5 0.80
Total 106.9 100.0 0.85
C~ATIVEPRODUCTS
Recovered from lights + heavies
Primary non mag, non conductor 81.13 98.2
Scavo non mag, non conductor 7.54 94.4
Subtotal 88.67 98.0
Recovered from ultra heavies
Primary non mag, non conductor 1.68 85.0
Scav. non mag, non conductor 0.94 95.7
Subtotal 2.62 88.9
Total non mag, non conductor (inc!. -65 mesh) 91.30 97.7
Total conductor 5.56 55.2
Total HI magnetics 3.14 80.3
Head Calc. from all test products 100.00 94.8
*Based on feed to separation as 100%
**Based on original sample as 100%
40
based on heavy liquid separation to identify what portion of
impurities which are separable by density separation had not
been removed in the earlier air tabling step. The results of
this analysis are shown in Table 10.2. The column entitled
45 ">2.3 S.G., %" identifies the total amount of material
separated from the beneficiated ore by the additional heavy
liquid density separation step. Additionally, that column
shows subcolumns titled "Plus" and "Minus." These two
subcolumns represent a breakdown of the 'Total" percent-
50 age of material which is greater than 2.3 S.G. which falls
into either the coarser or finer portion of the particular
stream. For example, the 6xlO mesh fraction was broken
down into a 6x8 mesh fraction and an 8xl0 mesh fraction.
Thus, by comparing the "Plus" and "Minus" subcolumns of
55 the ">2.3 S.G., %," it can be seen that inefficiency in the air
tabling density separation tended to be at smaller particle
sizes within each size fraction because most of the higher
specific gravity material left by air tabling was in the smaller
particle sizes (the "Minus" subcolumn).
The columns titled "Insoluble Assay" and "Soluble
Assay" provide data on the portion of each stream which is
insoluble (i.e., impurity) before heavy liquid separation
(''Total'' subcolumn) and after heavy liquid separation
("<2.3 S.G." subcolumn). Thus, for example, the purity of
65 products resulting from beneficiating ore using air tabling
can be seen in the ''Total'' subcolumn of the "Soluble Assay"
column for each of the different streams. This purity can be
EXAMPLE 10
This example illustrates beneficiation of trona using air
tabling, electrostatic separation and magnetic separation,
and demonstrates a relationship between breadth of size
fractions and effectiveness of air tabling as the density
separation method by comparison with heavy liquid separation.
A sample of bulk trona from Bed 17 of the Green River
Formation in Wyoming was crushed to -6 mesh. The sample
was subsequently sized into size fractions of 6xlO mesh,
lOx20 mesh, 20x35 mesh, 35x65 mesh (Tyler mesh). Each
of the plus 65 mesh size fractions was then subjected to
initial density separation on an air table (Rougher Pass). The
Rougher Pass light fractions were subsequently sent through
a cleaner pass and for the 6xlO mesh fraction, the heavy
fraction was sent to a scavenger pass. The resulting separations
are shown in Table 10.1.
Each of the size fractions was then subsequently beneficiated
using either magnetic separation (in the case of 6xlO 60
mesh fraction) or electrostatic separation and magnetic
separation. The portions of material from each separation
reporting to various product streams are shown in Table
10.1.
The non-magnetic, in the case of the 6xlO mesh fraction,
and the non-rnagnetic/non-conductive fractions were then
further analyzed by conducting a second density separation
5,651,465
25
compared with the subsequent column. having a higher
purity. which identifies the purity of the beneficiated material
with the subsequent heavy liquid separation to indicate
a theoretical purity based on perfect density separation. In
addition, the improvement in trona purity between the 5
non-magnetidnon-conductive product which was not air
tabled and the non-magneticlnon-conductive product which
was air tabled can be seen by comparing the 'Total NonMagneticlNon-
Conductive from Untabled Feed" line with
the "Total Non-MagneticINon-Conductive from Cleaner 10
Lights" line in the "Cumulative Products" section of Table
10.2.
TABLE 1O.1-continued
Data from Air Table Tests on Bulk
Trona Sample Crushed to Minus 6 Mesh
TABLE 10.1
15
26
Product
Cleaner Pass
Heavies
Lights
Feed Calc.
20 x 35 MESH
Weight, % of
Size
Feed Fraction
2.5 2.3
97.5 90.1
100 92.4
Sample
0.3
11.1
11.4
Rougher Pass
Heavies
Lights
Feed Calc.
Cleaner Pass
Heavies
Lights
Feed Calc.
35 x 65 MESH
Rougher Pass
Heavies
Lights
Feed Calc.
Cleaner Pass
Heavies
Lights
Feed Calc.
MINUS 63 MESH (not air tabled)
TOTAL FEED CALC.
TABLE 10.2
7.8 7.8 1.0
92.2 92.2 11.3
100.0 100.0 12.3
6.8 6.3 0.8
93.2 85.9 10.6
100 92.2 11.3
3.8 3.8 0.2
96.2 96.2 5.4
100.0 100.0 5.6
0.7 0.7 0.0
99.3 95.5 5.3
100.0 96.2 5.4
25.2
100.0
Data from Electrostatic and Induced Roll Separations on Air Table Products Feed Crushed to minus 6 mesh
Insoluble Soluble
Weight Percent >2.3 S.G., % >2.3 S.G., Dist.• % Assay, % of Assay. % of
Product Feed Sample Plus Minus Total Plus Minus Size Total <2.3 SG Thtal <2.3 SG
6 x 10 MESH
Not Tabled
Mag 9.0 4.0
Non Mag 91.0 40.6 0.47 0.74 1.21 100.0 100.0 100.0 3.8 2.3 96.2 97.7
Feed Calc. 100.0 44.6
Rougher Lights
Mag 12.2 4.5
Non Mag 87.8 32.2 0.17 0.86 1.03 28.7 92.3 67.6 3.2 2.3 96.8 97.7
Feed Calc. 100.0 36.7
Scavenger Lights
Mag 4.6 0.4
Non Mag 95.4 7.3 1.02 2.26 3.28 39.3 55.3 49.0 6.7 2.4 93.3 97.6
Feed Calc. 100.0 7.7
Cleaner Lights
Mag 11.6 4.2
Non Mag 88.4 32.0 0.1 0.86 0.96 16.8 91.6 62.5 3.2 2.3 96.8 97.7
Feed Calc. 100.0 36.2
10 x 20 MESH
Not Tabled
Condo 20.6 2.5
Mag 1.7 0.2
Non MagINon Cond 77.6 9.6 0.6 1.32 1.92 100.0 100.0 100.0 5.1 3.1 94.9 96.9
Feed Calc. 100.0 12.3
5,651,465
27 28
TABLE 1O.2-continued
Data from Electrostatic and Induced Roll Separations on Air Table Products Feed Crushed to minus 6 mesh
Insoluble Soluble
Weight Percent >2.3 S.O., % >2.3 S.O., Dist., % Assay, % of Assay, % of
Product Feed Sample Plus Minus Total Plus Minus Size Total <2.3 SO Total <2.3 SO
Rougher Lights
Condo 15.0 1.7
Mag 2.4 0.3
Non MagINon Condo 82.6 9.4 0.06 0.52 0.58 9.9 38.8 29.8 3.6 3,1 96.4 96.9
Feed Calc. 100.0 11.4
Cleaner Lights
Condo 9.9 1.1
Mag 2.1 0.2
Non MagINon Condo 88.0 9.8 0.01 0.55 0.56 1.7 42.6 29.8 3 2.5 97 97.5
Feed Calc. 100.0 11.1
20 x 35 MESH
Not Tabled
Condo 18.2 2.2
Mag 2.9 0.4
Non MagINon Condo 78.9 9.7 0,682 2.24 2.86 100.0 100.0 100.0 5.4 3.1 94.6 96,9
Feed Calc. 100.0 12.3
Rougher Lights
Condo 15.8 1.8
Mag 2.3 0.3
Non MagINon Condo 81.9 9.3 0.15 1.93 2.08 23.1 82.2 69.4 4.7 3.1 95.3 96.9
Feed Calc. 100.0 11.3
Cleaner Lights
Condo 14.2 1.5
Mag 2.8 0.3
Non MagINon Condo 83.0 8.8 0.1 0.71 0.81 14.6 28.8 25.7 4.4 3.1 95,6 96.9
Feed Calc. 100.0 10.6
35 x 65 MESH
Not Tabled
Condo 8,6 0.5
Mag 5.5 0.3
Non MagINon Condo 85.9 4.8 3.18 3.09 6,27 100.0 100.0 100.0 9.2 3,5 90.8 96.5
Feed Calc. 100.0 5.6
Rougher Lights
Condo 10.0 0.5
Mag 3.2 0.2
Non MagINon Condo 86.8 4.7 0.45 2.44 2.89 13.8 no 44,9 5.3 2.6 94.7 97.4
Feed Calc. 100.0 5.4
Cleaner Lights
Condo 13.0 0.7
Mag 4.8 0.3
Non MagINon Condo 82.2 4.4 0.24 1.73 197 6.8 50,7 28.5 49 2.8 95,1 97.2
Feed Calc. 100.0 5.3
CUMULATIVE PRODUCTS
Total NMlNC from Untabled Feed 64.7 100.0 100.0 100.0 4.6 2.6 95.4 97.4
Total NMlNC from Rou. + Scav. 62.9 36.9 99.1 76.2 4.0 2.6 96.0 97.4
Lights 55.6 20.7 78.1 57.0 3,7 2.6 96.3 97.4
Total NMlNC from Rou. Lights 54.9 11.3 58.9 41.4 3.5 2.5 96.5 97.5
Total NMlNC from CI. Lights
Note: The >2.3 sink products from the non mag., non condo were screened at intermediate mesh sizes to determine the recoveries by particle size, i.e., the
6 x 10 m at 8 m, the 10 x 20 m at 14 m, the 20 x 35 m at 28 m, and the 35 x 65 m at 48 m.
50
EXAMPLE 11
This example illustrates beneficiation of trona using air
tabling, electrostatic separation and magnetic separation,
and demonstrates a relationship between breadth of size
fractions and effectiveness of air tabling as the density
separation method by comparison with heavy liquid separation.
A sample of bulk trona from Bed 17 of the Green River
Formation in Wyoming was crushed to .-10 mesh, The
sample was subsequently sized into size fractions of 10x20
mesh, 20x35 mesh and 35x65 mesh (Tyler mesh). Each of
the size fractions was then subjected to initial density
separation on an air table (Rougher Pass). The size fractions
were subsequently sent through a cleaner and for the lOx20
mesh fractions, a scavenger pass, The resulting separations
are shown in Table 11.1.
Each of the size fractions was then subsequently beneficiated
using electrostatic separation and magnetic separation.
The portions of material from each separation reporting
to various product streams are shown in Table 11.1.
55 The non-magnetidnon-conductive fractions were then
further analyzed by conducting a second density separation
based on heavy liquid separation to identify what portion of
impurities which are separable by density separation had not
been removed in the earlier air tabling step, The results of
60 this analysis are shown in Table 11.2. The column entitled
">2.3 S,G.. %" identifies the total amount of material
separated from the beneficiated ore by the additional heavy
liquid density separation step. Additionally, that column
shows subcolumns titled "Plus" and "Minus," These two
65 subcolumns represent a breakdown of the 'Total" percentage
of material which is greater than 2.3 S,G, which falls
into either the coarser or finer portion of the particular
5,651,465
29
stream. For example. the lOx20 mesh fraction was broken
down into a lOx14 mesh fraction and an 14x20 mesh
fraction. Thus. by comparing the "Plus" and "Minus" subcolumns
of the ">2.3 S.G.• %." it can be seen that inefficiency
in the air tabling density separation tended to be at 5
smaller particle sizes within each size fraction because most
of the higher specific gravity material left by air tabling was
in the smaller particle size (the "Minus" column).
10
The columns titled "Insoluble Assay" and "Soluble
Assay" provide data on the portion of each stream which is
insoluble (i.e., impurity) before heavy liquid separation 15
("Total" subcolumn) and after heavy liquid separation
("<2.3 S.G." subcolumn). Thus. for example, the purity of
products resulting from beneficiating ore using air tabling
can be seen in the 'Total" subcolumn of the "Soluble Assay" 20
column for each of the different streams. This purity can be
compared with the subsequent column, having a higher
purity. which identifies the purity of the beneficiated material
with the subsequent heavy liquid separation to indicate 25
a theoretical purity based on perfect density separation. In
addition, the improvement in trona purity between the
non-magnetidnon-conductive product which was not air
30
tabled and the non-magnetic/non-conductive product which
was air tabled can be seen by comparing the 'Total NonMagneticlNon-
Conductive from Untabled Feed" line with
the 'Total Non-MagnetidNon-Conductive from Cleaner 35
lights" line in the "Cumulative Products" section of Table
11.2.
30
TABLE 11.1
Data from Air Table Tests on Bulk
Trona Sample Crushed to Minus 10 Mesh
Weight, % of
Size
Product Feed Fraction Sample
10 x 20:MESH
Rougher Pass
Heavies 13.6 13.6 4.1
Lights 86.4 86.4 26.3
Feed Calc. 100.0 100.0 30.4
Scavenger Pass
Heavies 8.2 1.8 0.3
Lights 91.8 12.5 3.8
Feed Calc. 100.0 14.3 4.1
Cleaner Pass
Heavies 3.0 2.6 0.8
Lights 97.0 83.8 25.5
Feed Calc. 100.0 86.4 26.3
20 x 35:MESH
Rougher Pass
Heavies 1.3 1.3 0.3
Lights 98.7 98.7 20.1
Feed Calc. 100.0 100.0 20.4
Cleaner Pass
Heavies 4.4 4.3 0.9
Lights 95.6 94.4 19.2
Feed Calc. 100.0 98.7 20.1
35 x 65:MESH
Rougher Pass
Heavies 13.0 13.0 1.1
Lights 87.0 87.0 7.4
Feed Calc. 100.0 100.0 8.5
Cleaner Pass
Heavies 18.0 15.7 1.3
Lights 82.0 71.3 6.1
Feed Calc. 100.0 87.0 7.4
MINUS 65 :MESH (not air tabled) 40.7
TOTAL FEED CALC. 100.0
TABLE 11.2
Data from Electrostatic and Induced Roll Separations on Air Table Products Feed Crushed to minus 10 mesh
Insoluble Soluble
Weight Percent >2.3 S.G.• % >2.3 S.G., Dist., % Assay, % of Assay, % of
Product Feed Sample Plus Minus Total Plus Minus Size Total <2.3 SG Total <2.3 SG
6 x 10:MESH
Not Tabled
Cond 24.7 7.5
Mag 1.6 0.5
Non MagINon Condo 73.7 22.4 0.59 1.19 1.78 100.0 100.0 100.0 4.0 2.6 96.0 97.4
Feed Calc. 100.0 30.4
Rougher Lights
Cond 16.4 4.4
Mag 3.6 0.9
Non MagINon Condo 79.8 21.0 0.06 0.7 0.76 9.5 55.1 40.0 2.7 2.4 97.3 97.6
Feed Calc. 100.0 26.3
Scavenger Lights
Cond 23.1 0.9
Mag 3.7 0.1
Non MagINon Cond 73.1 2.8 0.51 3.05 3.56 10.7 31.8 24.8 6.5 2.3 93.5 97.7
Feed Calc. 100.0 3.8
Cleaner Lights
Cond 23.1 5.9
Mag 3.7 1.0
Non MagINon Condo 73.1 18.6 0.02 0.63 0.65 2.8 44.1 30.4 2.5 2.3 97.5 97.7
Feed Calc. 100.0 25.5
20 x35 MESH
Not Tabled
Condo 4.2 0.9
5,651,465
31 32
TABLE I1.2-continued
Data from Electrostatic and fuduced Roll Separations on Air Table Products Feed Crushed to minus 10 mesh
Insoluble Soluble
Weight Percent >2.3 S.G., % >2.3 S.G., Dis!., % Assay, % of Assay, % of
Product Feed Sample Plus Minus Total Plus Minus Size Total <2.3 SG Total <2.3 SG
Mag 9.7 2.0
Non MagINon Condo 86.1 17.6 1.48 1.61 3.09 100.0 100.0 100.0 6.2 3.7 93.8 96.3
Feed Calc. 100.0 20.4
Rougher Lights
Condo 4.8 1.0
Mag 10.1 2.0
Non MagINon Condo 85.1 17.1 0.44 1.72 2.16 29.0 104.1 68.1 5.5 3.7 94.5 96.3
Feed Calc. 100.0 20.1
Cleaner Lights
Condo 4.6 0.9
Mag 8.6 1.7
Non MagINon Condo 86.8 16.7 0.23 1.29 1.52 14.7 76.0 46.7 4.7 3.9 95.3 96.1
Feed Calc. 100.0 19.2
35 x 65 MESH
Not Tabled
Condo 10.8 0.9
Mag 6.6 0.6
Non MagINon Condo 82.6 7.0 0.66 1.8 2.46 100.0 100.0 100.0 5.4 2.8 94.6 97.2
Feed Calc. 100.0 8.5
Rougher Lights
Condo 12.5 0.9
Mag 5.8 0.4
Non MagINon Condo 81.7 6.0 0.29 1.33 1.62 37.8 63.6 56.7 4.5 3.2 95.5 96.8
Feed Calc. 100.0 7.4
Cleaner Lights
Condo 13.3 0.8
Mag 2.8 0.2
Non MagINon Condo 83.9 5.1 0.16 1.56 1.72 17.7 63.2 51.0 4.1 2.5 95.9 97.5
Feed Calc. 100.0 6.1
CUMUL..ITI\'E PRODUCTS
Total NMlNC from Untabled Feed 47.0 100.0 100.0 100.0 5.0 3.0 95.0 97.0
Total NMlNC from Rou. + Scav. 46.9 27.3 89.8 65.2 4.2 3.0 95.8 97.0
Lights 44.1 24.0 77.2 56.3 4.0 3.0 96.0 97.0
Total NMlNC from Rou. Lights 40.4 11.5 61.0 41.5 3.6 3.0 %.4 97.0
Total NMlNC from Cl. Lights
Note: The >2.3 sink products from the non mag., non condo were screened at intermediate mesh sizes to determine the recoveries by particle size, i.e., the
10 x 20 m at 14 m, the 20 x 35 m at 28 m, and the 35 x 65 m at 48 m.
45
8. A process, as claimed in claim 1, wherein the purity of
said recovered saline mineral is at least about 85% after all
of said steps.
9, A process, as claimed in claim 1, further comprising,
before steps (b) and (c), the step of de-dusting said ore to
recover fines.
10. A process, as claimed in claim 1, further comprising,
before step (a), the step of reducing a particle size of said ore
50 before said separating steps.
11. A process, as claimed in claim 1, further comprising,
before step (a), the step of sizing the ore into between three
and ten size fractions before said separating steps.
12. A process, as claimed in claim 1, further comprising,
55 before step (a), the step of drying the ore to remove surface
moisture therefrom.
13. Aprocess, as claimed in claim 1, wherein a maximum
particle size before all of said steps is about 6 mesh.
14. A process, as claimed in claim 1, wherein a minimum
60 particle size before all of said steps is about 100 mesh.
15. A process, as claimed in claim 1, further comprising
the steps of:
scavenging a recovered portion from one or more of said
first, second and third portions of impurities; and
recycling said recovered portion back to said process.
16. A process, as claimed in claim 1, further comprising
an additional separating step on said ore selected from the
What is claimed is:
1. A process for recovering a saline mineral from an ore
containing said saline mineral and impurities, comprising
the steps of:
(a) separating a first portion of impurities from the ore by
density separation such that materials of different densities
separate from each other;
(b) electrostatically separating a second portion of impurities
from the ore; and
(c) magnetically separating a third portion of impurities
from the ore, whereby a recovered saline mineral is
produced after all of said steps.
2. A process, as claimed in claim 1, wherein said density
separation comprises a process selected from the group
consisting of air tabling or dry jigging.
3. A process, as claimed in claim 2, wherein said density
separation comprises air tabling.
4. A process, as claimed in claim 1, wherein said first
portion of impurities is more dense than said saline mineral.
5. A process, as claimed in claim 1, wherein said first
portion of impurities comprises shortite.
6. A process, as claimed in claim 1, wherein said second
portion of impurities is more electrically conductive than
said saline mineral,
7. A process, as claimed in claim 1, wherein said third 65
portion of impurities is more magnetic than said saline
mineral.
5,651,465
33
group consisting of density separation, electrostatic separation
and magnetic separation to further remove impurities
therefrom.
17. A process, as claimed in claim I, wherein a weight
recovery of said saline mineral resulting from said density 5
separation step is between about 65% and about 95%,
18. A process, as claimed in claim I, wherein said
recovered saline mineral comprises trona.
19. A process, as claimed in claim 18, wherein. said first
portion of impurities comprises shortite. 10
20. A process, as claimed in claim 18, wherein the purity
of said recovered saline mineral is at least about 85% after
all of said steps.
21. A process, as claimed in claim 20, wherein the purity
of said recovered saline mineral is at least about 97% after 15
all of said steps.
22. A process, as claimed in claim 18, further comprising
the steps of:
scavenging a recovered portion from said first portion of
impurities; and 20
recycling said recovered portion back to said process.
23. A process, as claimed in claim 18, wherein a weight
recovery of said saline mineral resulting from said density
separation step is between about 65% and about 95%.
24. A process for recovering trona from an ore containing 25
trona and impurities, comprising the steps of:
(a) reducing a particle size of the ore to less than about 6
mesh;
(b) sizing the ore into between three and ten size fractions;
and
34
(c) separating a first portion of impurities compnsmg
shortite from a first fraction by a density separation
method such that materials of different densities separate
from each other, whereby a recovered saline mineral
is produced after all of said steps.
25. Aprocess, as claimed in claim 24, further comprising:
(d) electrostatically separating a second portion of impurities
from said first fraction, said second portion being
more electrically conductive than trona.
26. Aprocess, as claimed in claim 24, further comprising:
(d) magnetically separating a second portion of impurities
from said first fraction, said second portion being more
magnetic than trona.
27.Aprocess, as claimed in claim 24, wherein a minimum
particle size before said separating step is about 100 mesh in
diameter.
28. A process, as claimed in claim 24, wherein the purity
of said trona is at least about 85% after said separating step.
29. A process, as claimed in claim 28, wherein the purity
of said trona is at least about 97% after said separating step.
30. Aprocess, as claimed in claim 25, further comprising,
before step (d), the step of de-dusting said first fraction to
recover fines and wherein said fines have a purity of greater
than about 94%.
31. Aprocess, as claimed in claim 24, further comprising,
before step (c), the step of:
drying the first fraction to remove moisture therefrom.
* * * * *