5,470,554
Nov. 28, 1995
United States Patent [19]
Schmidt et al.
111111111111111111111111111111111111111111 111111111111111111111111111111111
US005470554A
[11] Patent Number:
[45] Date of Patent:
[54] BENEFICATION OF SALINE MINERALS
[75] Inventors: Roland Schmidt, Lakewood; Dale L.
Denham, Jr., Louisville, both of Colo.
4,943,368 711990 Gilbert et al 209/40
5,096,678 311992 Mackie 423/27
OTHER PUBLICATIONS
22 Claims, No Drawings
Primary Examiner-Steven Bos
Attorney, Agent, or Firm-Sheridan Ross & McIntosh
Perry & Chilton, Chemical Engineers' Handbook, 5th ed.
1973, pp. 8-31, no month.
Perry, Chilton and Kirkpatrick, Chemical Engineers Handbook,
4th Ed. (1963), pp. 21-61 to 21-70.
A process is provided for recovering a saline rnineJ;a1 from
an ore containing the saline mineral and impurities. The
process generally comprises 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 surfa.ce moisture therefrom and de-dusting the ore to
recover valuable fines.
[57] ABSTRACT
[73] Assignee: Environmental Projects, Inc., Casper,
Wyo.
[56] References Cited
U.S. PATENT DOCUMENTS
2,981,600 411961 Porter 423/121
3,244,476 411966 Smith 23/63
3,819,805 611974 Graves et al 423/206
3,869,538 311975 Sproul et al. . 423/206
4,202,667 511980 Conroy et al 423/206.2
4,238,277 811981 Brison et al 2091166
4,341,744 711982 Brison et al 423/206 T
4,363,722 1211982 Dresty, Jr. et al 209/40
4,375,454 311983 hnperto et al. 423/206 T
4,512,879 4/1985 Attia et al 209/40
[21] Appl. No.: 66,871
[22] Filed: May 25, 1993
[51] Int. Cl.6 C22B 26/00; B03C 1/30;
B03C 7/00
[52] U.S. CI 423/206.2; 209/40; 209/131
[58] Field of Search 209/40, 131; 4231206.2,
423/121
5,470,554
2
DETAILED DESCRIPTION OF THE
INVENTION
ing the saline mineral and impurities. The process generally
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
5 separatin£ a third portion of impurities from the ore.
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
10 beneficiating trona from an ore containing trona and impurities.
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
15 production of caustic soda by the lime-soda process. The
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
20 separating a third portion of impurities from the ore. The
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
25 recovering alumina from the solution.
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 ofimpurities 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 several locations
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
65 River Formation in Wyoming has been found to have
between about 80 and about 90 wt. % trona. The remaining
10 to 20 wt. % of the ore in the Green River Formation
1
BENEFICATION OF SALINE MINERALS
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.
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 (NlLzC03.NaHC03.2H20), highpurity
trona is commonly used to make soda ash, which is
used in the production of glass and paper. Naturally-occurring
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 30
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, 35
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 40
can be produced utilizing trona having less than 97% purity.
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 45
the crude trona, classifying the trona by particle size, electrostatically
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 50
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 55
a purity. Consequently, these industries generally use trona
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 60
and in particular, trona, resulting in higher purities than
existing dry beneficiation processes and which is simpler
and less expensive than known wet beneficiation processes.
SUMMARY OF THE INVENTION
The present invention is embodied in a process for
recovering a high-purity saline mineral from an ore contain5,470,554
3
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
traces of other impurities. Other samples of trona ore can
i~clude different percentages of trona and impurities, as well 5
as include other impurities.
The present process includes removing a first portion of
impurities from an ore containing saline minerals by a
density separation method. Density separation methods are
based on subjecting an ore to conditions such that materials 10
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
separation step of the present invention is most preferably a
dry process, however, wet density separation processes, such 15
as heavy media separation, can be used as well. In dry
density separation processes, the need for processing in a
saturated brine solution, solidfbrine separation, and drying
of the product is eliminated. Consequently, the process
according to the present invention is much cheaper and less 20
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 dif- 25
ferent 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
into more than two streams of varying densities. Typically,
in the case of beneficiating trona, trona is recovered in the 30
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
lower weight recoveries, the recovered stream will have a
higher purity, but the rougher stage process will also have a 35
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
processing (e.g., separation) of the ore and, in addition, may
be of higher value because it can be used in other applica- 40
tions where high purity saline minerals are required.
In the case of beneficiating trona, for example, the weight
recovery (weight of trona recovered/weight of trona in the
feed stream) from the density separation step is between 45
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 50
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
scavenger step recovers a portion of the impurity stream
from the rougher pass having the saline mineral in it and 55
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
further size reduction.
In a further alternative embodiment, the recovered stream 60
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
of the final product. The cleaning step is similar to the
above-described density separation process in that impuri- 65
ties are removed from the stream by density separation. In
both scavenging and cleaning passes, the feed stream into
4
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
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
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.
The present process further includes a magnetic separation
step which subjects the ore to conditions such that
5,470,554
5
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. Pref- 5
erably, 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 10
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 15
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 improv~, the overall recovery. The scav- 20
enger 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
the process with or without further size reduction to increase
the overall yield of the magnetic separation step. Further- 25
more, 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 30
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 35
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, 40
cone crushing, autogenous crushing or semiautogenous
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 min- 45
erals 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 50
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 55
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 60
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 fraction, 65
the higher the efficiency of removal of impurities. On the
other hand, a larger number of fractions will increase the
6
efficiency, but may increase the cost of the overall process.
The use of between 3 and 10 fractions has been 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 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 (Tyler mesh).
In yet another embodiment of the present invention, the
ore is dried prior to the separation processes set forth above.
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
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 interfere
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 industrial 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 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, typically
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
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
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
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
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 beneficiated
trona, the total cost for caustic can be significantly
below that of caustic currently used in the alumina industry.
5,470,554
8
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
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
fractions was subjected to high intensity magnetic separation
10 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 separation
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 of2.14; the majorimpurity was shortite, having
a specific gravity of 2.6; and other impurities having a
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 dafa generated from the foregoing beneficiation processes
is shown in Tables 1-8. As can be seen from the
25 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
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).
EXAMPLES 1-8
Eight samples of trona-containing ore from Bed 17 of the
Green River Formation in Wyoming were beneficiated in
accordance with the present invention. Each of the samples
7
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 5
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 teach- 15
ings, 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 20
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.
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 93.8 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 8.0
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 n.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
5,470,554
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.
non-conductive! 40.3 2.9 12.9 77.4 2.6 22.6 5.4
non-magnetic
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
Trona Prod., Calc. 22.8 100.0 79.7 20.7 20.3 37.8
Trona + 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 Density Separation of Plus 65 Mesh Non-Magnetic!
Non-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.
10 x 20 mesh
conductive stream 57.6 27.6 87.7 40.9 12.3 8.3
magnetic stream 3.7 1.8 68.1 2.0 31.9 1.4
non-conductive! 38.7 18.6 49.4 19.1 6.0 80.9 36.9
non-magnetic
stream
Total 100.0 47.9 60.4 48.9 39.6 46.6
20 x 35 mesh
conductive stream 30.0 3.7 81.3 5.0 18.7 1.7
magn.etic stream 15.9 2.0 62.9 2.1 37.1 1.9
non-conductive! 54.1 6.6 17.7 46.7 5.2 53.3 8.7
non-magnetic
stream
Total 100.0 12.3 59.6 12.4 40.4 12.2
35 x 65 mesh
conductive stream 45.8 9.1 82.8 12.8 17.2 3.9
magnetic stream 13.5 2.7 69.3 3.2 30.7 2.0
non-conductive! 40.7 8.1 21.6 47.7 6.5 52.3 10.4
non-magnetic
stream
Total 100.0 20.0 66.7 22.5 33.3 16.3
65 x 150 mesh
conductive stream 22.0 1.6 82.9 2.2 17.1 0.7
magnetic stream 20.1 1.5 74.3 1.8 25.7 0.9
non-conductive! 57.9 4.2 11.2 42.0 3.0 58.0 6.0
non-magnetic
stream
Total 100.0 7.3 57.5 7.1 42.5 7.6
Minus 150 mesh 12.5 43.6 9.2 56.4 17.3
Plus 65 mesh trona 33.4 31.6 17.8 68.4 56.0
Trona Prod., Calc. 37.6 100.0 32.7 20.8 67.3 62.0
5,470,554
11 12
TABLE 2-continued
Electrostatic and Magnetic Separation of Trona-Containing Waste Rock; Sample 2
Weight Percent Assay
Beneficiated Insoluble Soluble
Fraction Fraction Sample Product % Distr. % Distr.
Trona + minus 50.1 35.5 30.0 64.5 79.3
150 Calc.
Sample Calc. 100.0 59.2 100.0 40.8 100.0
Heavy Liquid Density Separation of Plus 65 Mesh
Non-MagneticlNon-Conductive Sample 2
<2.0 S.O. 6.0 2.0
2.0 x 2.3 S.O. 63.0 21.0 4.7 1.7 95.3 49.1
>2.3 S.O. 31.0 10.3 92.3 16.1 7.7 6.9
Total 100.0 33.4 31.6 17.8 68.4 56.0
TABLE 3
Electrostatic and Magnetic Separation of Trona-Containing Waste Rock; Sample 3
Weight Percent Assay
Beneficiated 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 Il.l 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 l.l
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! 68.7 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.O. 0.2 0.1
2.0 x 2.3 S.O. 96.1 53.2 1.2 8.2 98.8 57.1
5,470,554
13 14
TABLE 3-continued
Electrostatic and Magnetic Separation of Trona-Containing Waste Rock; Sample 3
Weight Percent Assay
Beneficiated Insoluble Soluble
Fraction Fraction Sample Product % Distr. % Distr.
>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
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 1&.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
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-conductive! 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 98.4 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
5,470,554
15 16
TABLE 5
Electrostatic and Magnetic Separation of Trona-Containing Waste Rock; Sample 5
Weight Percent Assay
Beneficiated Insoluble 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-conductive! 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-conductive! 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-conductive! 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-conductive! 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
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
5,470,554
17 18
TABLE 6-continued
Electrostatic and Magnetic Separation of Trona-Containing Waste Rock; Sample 6
Weight Percent Assay
Beneficiated Insoluble Soluble
Fraction Fraction Sample Product % Distr. % Distr.
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
non-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 Liqnid Density Separation of Plus 65 Mesh
Non-Magnetic/Non-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
TABLE 7
Electrostatic and Magnetic Separation of Trona-Containing Waste Rock; Sample 7
Weight Percent Assay
Beneficiated 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-conductivel 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
5,470,554
19 20
TABLE 7-continued
Electrostatic and Magnetic Separation of Trona-Containing Waste Rock; Sample 7
Weight Percent Assay
Beneficiated Insoluble Soluble
Fraction Fraction Sample Product % Distr. % Distr.
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
Total 100.0 62.7 8.2 49.9 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 18.9 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
5,470,554
21 22
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.
35 x 65 mesh
conductive stream 10.0 1.1 50.2 5.9 49.8 0.6
magnetic stream 3.2 OJ 48.9 1.8 51.1 0.2
non-conductive! 86.7 9.3 14.4 6.9 7.0 93.1 9.6
non-magnetic
stream
Totai 100.0 10.8 12.6 14.7 87.4 10.4
65 x 150 mesh
conductive stream 12.7 1.5 22.1 3.6 77.9 1.3
magnetic stream 2.5 0.3 32.0 1.0 68.0 0.2
non-conductive! 84.8 10.0 15.4 3.6 3.9 96.4 10.6
non-magnetic
stream
Total 100.0 11.8 6.7 8.5 93.3 12.1
Minus 150 mesh 21.9 3.9 9.2 96.1 23.2
Plus 65 mesh trona 54.7 5.5 32.5 94.5 57.0
Trona Prod., Calc. 64.7 100.0 5.2 36.4 94.8 67.6
Trona + minus 86.6 4.9 45.6 95.1 90.8
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.O. 0.3 0.2
2.0 x 2.3 S.O. 97.0 53.1 2.0 11.5 98.0 57.3
>2.3 S.G. 2.7 1.5
Total 100.0 54.7 5.5 32.5 94.5 57.0
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, available
from Solvay Minerals S.A., Green River, Wyo. The
T-50 material has a trona purity of about 95% and a size
range of 20xl50 mesh Tyler.
The ore sample was first classified using a screening
process to divide the ore sample into three size fractions:
+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
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
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
fraction, and the -65 mesh size fraction that was not air
tabled. Each of the above-identified electrostatic separation
processes divided the sample into three electrostatic fractions:
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
40 9, as noted above.
The non-conductors and middlings from each of the
above-referenced electrostatic separation processes were
individually magnetically separated utilizing an induced roll
45 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 non-
50 magnetic. 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
55 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,
60 91.3% of the original sample was recovered as non-magnetic,
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
65 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.
5,470,554
23 24
TABLE 9 TABLE 9-continued
Density, Electrostatic and Magnetic Separation of Density, Electrostatic and Magnetic Separation of
Trona Ore; Sample 9 Trona Ore; Sample 9
5
Weight Weight
(g, unless (g, unless
otherwise Weight Percent Purity otherwise Weight Percent Purity
Separation noted Fraction' Sample" (% trona) Separation noted Fraction' Sample" (% trona)
10
SCREENING 35 x 65 mesh Non Condo from lights + heavies
plus 35 mesh 3621b 36.8 36.8 Hi Mag. 61.1 4.1 1.67
35 x 65 mesh 4821b 49.0 49.0 HI Non Mag. 1438.1 95.9 39.23
minus 65 mesh 140lb 14.2 14.2
15
Total 1499.2 100.0 40.90
Total 9841b 100.0 100.0 plus 35 mesh Non Condo from ultra heavies
AIR TABLE SEPARATIONS
plus 35 mesh HI Mag. 11.2 1.2 0.01
HI Non Mag. 931.7 98.8 0.90
illt. Heavy 1605 4.2 1.5
Heavy 1814 4.7 1.7 Total 942.9 100.0 0.91
Lights 34960 91.1 33.5 20 35 x 65 mesh Non Condo from ultra heavies
Total 38379 100.00 36.8 HI Mag. 53.1 8.9 0.08
35 x 65 mesh HI Non Mag. 541.7 91.1 0.78
illt. Heavy 800 2.4 1.2 Total 594.8 100.0 0.86
Heavy 1603.5 4.7 2.3 25 minus 65 mesh Non Condo
Lights 31560 92.9 45.5
HI Mag. 59.9 3.5 0.46
Total 33963.5 100.0 49.0 HI Non Mag. 1649.0 96.5 12.71
minus 65 mesh not air tabled
HIGH TENSION ELECTROSTATIC SEPARATIONS (HT) Total 1708.9 100.0 13.17
plus 35 mesh air table lights + heavies 30 plus 35 mesh HT Mid from lights + heavies
Condo 190.8 7.4 2.6 HI Mag. 15.6 7.8 0.25
Midd 230.5 8.9 3.1 HI Non Mag. 183.8 92.2 2.90
Non-Cond. 2159.5 83.7 29.5
Total 199.4 100.0 3.15
Total 2580.8 100.0 35.3
35
35 x 65 mesh HT Mid from lights + heavies
35 X 65 mesh air table lights + heavies
HI Mag. 13.8 6.0 0.29
Condo 90.4 4.5 2.2 HI Non Mag. 216.9 94.0 4.48
Midd 199.3 10.0 4.8
Non-Cond. 1709.5 85.5 40.9 Total 230.7 100.0 4.77
minus 65 mesh HT Mid
Total 1999.2 100.0 47.8 40
plus 35 mesh air table nltra heavies HI Mag. 11.8 12.2 0.02
HI Non Mag. 85.1 87.8 0.16
Condo 467.3 29.2 0.4
Midd 188.7 1l.8 0.2 Total 96.9 100.0 0.18
Non-Cond. 943 59.0 0.9 plus 35 mesh HT Mid from ultra heavies
45
Total 1599 100.0 1.5 HI Mag. 7.6 4.0 0.01
35 x 65 mesh air table ultra heavies HI Non Mag. 181.2 96.0 0.15
Condo 97 12.1 0.1 Total 188.8 100.0 0.15
Midd 106.8 13.4 0.2 35 x 65 mesh HT Mid from ultra heavies
Non-Cond. 595 74.5 0.9 50
HI Mag. 6.9 6.5 0.05
Total 798.8 100.0 1.2 HI Non Mag. 100.0 93.5 0.80
minus 65 mesh
Total 106.9 100.0 0.85
Condo 23.4 1.4 0.2 CUMULATIVE PRODUCTS
Midd 96.9 6.0 0.9
55
Recovered from lights + heavies
Non-Cond. 1500.6 92.6 13.2
Primary non mag, non conductor 81.13 99.2
Total 1620.9 100.0 14.2 Scavo non mag, non conductor 7.54 94.4
HIGH INTENSITY MAGNETIC SEPARATIONS (HI)
plus 35 mesh Non Condo from lights + heavies Subtotal 88.67 98.0
Recovered from ultra heavies
HI Mag. 22.6 1.0 0.31 60
HI Non Mag. 2136.0 99.0 29.19 Primary non mag, non conductor 1.68 85.0
Scavo non mag, non conductor 0.94 95.7
Total 2158.6 100.0 29.50
Subtotal 2.62 88.9
65
noted Fraction" Sample""
Weight
(g, unless
otherwise Weight Percent
Density, Electrostatic and Magnetic Separation of
Trona Ore; Sample 9
Purity
26
("Total" subco1umn) 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"
5 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
a theoretical purity based on perfect density separation. In
10 addition, the improvement in trona purity between the
non-magnetic/non-conductive product which was not air
tabled and the non-magnetic/non-conductive product which
was air tabled can be seen by comparing the "Total NonMagnetic/
Non-Conductive from Untabled Feed" line with
15 the "Total Non-Magnetic/Non-Conductive from Cleaner
Lights" line in the "Cumulative Products" section of Table
10.2.
5,470,554
97.7
55.2
80.3
94.8
(% trona)
91.30
5.56
3.14
100.00
25
TABLE 9-continued
Separation
"Based on feed to separation as 100%
""Based on original sample as 100%
Total non mag, non conductor (incl. -65
mesh)
Total conductor
Total HI magnetics
Head Calc. from all test products
EXAMPLE 10 TABLE 10.1
Data from Air Table Tests on Bulk Trona Sample
Crushed to Minus 6 Mesh
0.2
7.7
7.9
0.2
5.4
5.6
0.3
11.1
11.4
0.9
11.4
12.3
7.9
36.7
44.6
0.6
36.2
36.7
1.0
11.3
12.3
0.8
10.6
11.3
0.0
5.3
5.4
25.2
100.0
1.2
81.1
82.3
3.1
17.2
20.3
2.3
90.1
92.4
0.7
95.5
96.2
6.3
85.9
92.2
7.6
92.4
100.0
7.8
92.2
100.0
17.7
82.3
100.0
3.8
96.2
100.0
Size Fraction Sample
Weight, % of
Feed
1.5
98.5
100.0
2.5
97.5
100.0
7.6
92.4
100.0
17.7
82.3
100.0
2.8
97.2
100.0
7.8
92.2
100.0
3.8
96.2
100.0
6.8
93.2
100.0
0.7
99.3
100.0
Heavies
Lights
Feed Calc.
Cleaner Pass
Heavies
Lights
Feed Calc.
20 x 35 MESH
Rougher Pass
Heavies
Lights
Feed Calc.
10 x 20 MESH
Rougher Pass
Heavies
Lights
Feed Calc.
Cleaner Pass
Heavies
Lights
Feed Calc.
Scavenger Pass
Heavies
Lights
Feed Calc.
Cleaner Pass
Heavies
Lights
Feed Calc.
MINUS 65 MESH (not air tabled)
TOTAL FEED CALC.
Heavies
Lights
Feed Calc.
Cleaner Pass
Heavies
Lights
Feed Calc.
35 x 65 MESH
Rougher Pass
Product
25 6 x 10 MESH
Rougher Pass
This example illustrates beneficiation of trona using air 20
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 30
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. 35
Each of the size fractions was then subsequently beneficiated
using either magnetic separation (in the case of 6xlO
mesh fraction) or electrostatic separation and magnetic
separation. The portions of material from each separation 40
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-magnetic/non-conductive fractions were then
further analyzed by conducting a second density separation 45
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
">2.3 S.G., %" identifies the total amount of material 50
separated from the beneficiated ore by the additional heavy
liquid density separation step. Additionally, that column
shows subco1umns titled "Plus" and "Minus." These two
subcolumns represent a breakdown of the "Total" percentage
of material which is greater than 2.3 S.G. which falls 55
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 8x10 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 60
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 65
Assay" provide data on the portion of each stream which is
insoluble (Le., impurity) before heavy liquid separation
5,470,554
27 28
TABLE 10.2
Data from Electrostatic and Induced Roll Separation on NT Table Products
Feed Crushed to minus 6 mesh
Weight Insoluble Soluble
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
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 MaglNon Condo 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
Rougher Lights
Condo 15.0 1.7
Mag 2.4 0.3
Non MaglNon 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 MaglNon 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 MaglNon Condo 78.9 9.7 0.62 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 MaglNon 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 MaglNon 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 MaglNon 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 MaglNon Condo 86.8 4.7 0.45 2.44 2.89 13.8 77.0 44.9 5.3 2.6 94.7 97.4
29
5,470,554
30
TABLE 1O.2-continued
Data from Electrostatic and Induced Roll Separation on Air Table Products
Feed Crushed to minus 6 mesh
Weight Insoluble Soluble
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
Feed Calc. 100.0 5.4
Cleaner Lights
Condo 13.0 0.7
Mag 4.8 0.3
Non MaglNon Condo 82.2 4.4 0.24 1.73 1.97 6.8 50.7 28.5 4.9 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. + Scavo 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 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, Le., 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 mat 48 m.
Size Fraction Sample
Weight, % of
Feed
13.6 13.6 4.1
86.4 86.4 26.3
100.0 100.0 30.4
8.2 1.8 0.3
91.8 12.5 3.8
100.0 14.3 4.1
3.0 2.6 0.8
97.0 83.8 25.5
100.0 86.4 26.3
TABLE 11.1
Data from Air Table Tests on Bulk Trona Sample
Crushed to Minus 10 Mesh
45
25 Assay" provide data on the portion of each stream which is
insoluble (Le., impurity) before heavy liquid separation
(''Total'' subcolumn) and after heavy liquid separation
("<2.3 S.G." subcolumn). Thus, for example, the purity of
30 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
compared with the subsequent column, having a higher
purity, which identifies the purity of the beneficiated mate-
35 rial 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
non-magnetic/non-conductive product which was not air
tabled and the non-magnetic/non-conductive product which
40 was air tabled can be seen by comparing the ''Total NonMagneticlNon-
Conductive from Untabled Feed" line with
the ''Total Non-MagneticlNon-Conductive from Cleaner
Lights" line in the "Cumulative Products" section of Table
11.2.
Product
10 x 20 MESH
Rougher Pass
55
Heavies
Lights
Feed Calc.
Scavenger Pass
60 Heavies
Lights
Feed Calc.
Cleaner Pass
Heavies
65
Lights
Feed Calc.
20 x 35 MESH
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 lOx20
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 IOx20
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.
The non-magnetic/non-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 50
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
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
stream. For example, the lOx20 mesh fraction was broken
down into a lOxl4 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
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).
The columns titled "Insoluble Assay" and "Soluble
5,470,554
31
TABLE 11. I-continued
Data from Air Table Tests on Bulk Trona Sample
Crushed to Minus 10 Mesh
5
Weight, % of
32
TABLE 11. I-continued
Data from Air Table Tests on Bulk Trona Sample
Crushed to Minus 10 Mesh
Weight, % of
Product Feed Size Fraction Sample Product Feed Size Fraction Sample
Rougher Pass
Heavies
Lights
Feed Calc.
Cleaner Pass
Heavies
Lights
Feed Calc.
35 x 65 MESH
~ougher Pass
10
1.3 1.3 0.3 Heavies 13.0 13.0 1.1
98.7 98.7 20.1 Lights 87.0 87.0 7.4
100.0 100.0 20.4 Feed Calc. 100.0 100.0 8.5
Cleaner Pass
4.4 4.3 0.9
15
Heavies 18.0 15.7 1.3
95.6 94.4 19.2 Lights 82.0 71.3 6.1
100.0 98.7 20.1 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
Weight Insoluble Soluble
Percent >2.3 S.G., % >2.3 S.G., Disl., % Assay, % of Assay, % of
Product Feed Sample Plus Minus Total Plus Minus Size Total <12.3 SG Total <2.3 SG
10 x 20 MESH
Not Tabled
Condo 24.7 7.5
Mag 1.6 0.5
Non MaglNon 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
Condo 16.6 4.4
Mag 3.6 0.9
Non MaglNon 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
Condo 23.1 0.9
Mag 3.7 0.1
Non MagINon Condo 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
Condo 23.1 5.9
Mag 3.7 1.0
Non MaglNon 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 x 35 MESH
Not Tabled
Condo 4.2 0.9
Mag 9.7 2.0
Non MaglNon 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 MaglNon 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 MaglNon 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
5,470,554
33 34
TABLE I1.2-continued
Data from Electrostatic and Induced Roll Separations on Air Table Products
Feed Crushed to minus 10 mesh
Weight Insoluble Soluble
Percent >2.3 S.G., % >2.3 S.G., Dis!., % Assay, % of Assay, % of
Product Feed Sample Plus Minus Total Plus Minus Size Total <12.3 SG Total <2.3 SG
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 MaglNon 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
CUMULATIVE PRODUCTS
Total NMlNC from Untabled 47.0 100.0 100.0 100.0 5.0 3.0 95.0 97.0
Feed
Total NMlNC from Rou. + 46.9 27.3 89.8 65.2 4.2 3.0 95.8 97.0
Scavo
Lights 44.1 24.0 77.2 56.3 4.0 3.0 96.0 97.0
Total NMlNC from Rou. 40.4 1l.5 61.0 41.5 3.6 3.0 96.4 97.0
Lights
Total NMINC from Cl. Lights
NOTE:
The >2.3 sink products from the non mag., non condo were screened at intermediate mesh size 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.
What is claimed is:
1. A process for recovering trona from an ore containing
trona and impurities, comprising the steps of:
(a) reducing a particle size of said ore to less than about 40
6 mesh;
(b) sizing the ore into size fractions, wherein ore having
a particle size between about 6 mesh and about 100
mesh is sized into at least three size fractions;
(c) separating a first portion of impurities comprising 45
shortite from each of said fractions by subjecting each
fraction to a density separation method selected from
the group consisting of air tabling and dry jigging to
produce recovered trona;
(d) electrostatically separating a second portion of impu- 50
rities from each of said fractions to produce recovered
trona; and
(e) magnetically separating a third portion of impurities
from each of said fractions to produce recovered trona.
2. A process, as claimed in claim 1, wherein said density 55
separation comprises air tabling.
3. A process, as claimed in claim 1, wherein said first
portion of impurities is more dense than said trona.
4. A process, as claimed in claim 1, wherein said second
portion of impurities is more electrically conductive than 60
said trona.
5. A process, as claimed in claim 1, wherein said third
portion of impurities is more magnetic than said trona.
6. A process, as claimed in claim 1, wherein the purity of
said recovered trona is at least about 85% after all of said 65
steps.
7. A process, as claimed in claim 1, further comprising,
before steps (d) and (e), the step of de-dusting said ore to
recover fines.
8. A process, as claimed in claim 1, further comprising,
before step (c), the step of sizing the ore into between three
and ten size fractions before said separating steps.
9. A process, as claimed in claim 1, further comprising,
before step (c), the step of drying the ore to remove surface
moisture therefrom.
10. 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.
11. A process, as claimed in claim 1, further comprising
an additional separating step on said fractions selected from
the group consisting of density separation, electrostatic
separation and magnetic separation to further remove impurities
therefrom.
12. A process, as claimed in claim 1, wherein a weight
recovery of said trona resulting from said density separation
step-is between about 65% and about 95%.
13. A process, as claimed in claim 1, wherein the purity
of said recovered trona is at least about 85% after all of said
steps.
14. A process, as claimed in claim 13, wherein the purity
of said recovered trona is at least about 97% after all of said
steps.
15. A process, as claimed in claim 1, further comprising
the steps of:
scavenging a recovered portion from said first portion of
impurities; and
35
5,470,554
36
* * * * *
5
18. A process, as claimed in claim 16, further comprising:
(e) magnetically separating a second portion of impurities
from each of said fractions, said second portion being
more magnetic than trona.
19. A process, as claimed in claim 16, wherein the purity
of said trona is at least about 85% after said separating step.
20. A process, as claimed in claim 19, wherein the purity
of said trona is at least about 97% after said separating step.
21. A process, as claimed in claim 17, further comprising,
10 before step (e), the step of de-dusting each of said fractions
to recover fines and wherein said fines have a purity of
greater than about 94%.
22. A process, as claimed in claim 16, further comprising,
before step (c), the step of:
drying each of said fractions to remove moisture therefrom.
recycling said recovered portion back to said process.
16. A process for recovering trona from an ore containing
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 size fractions, wherein ore having
a particle size between 6 mesh and 100 mesh is sized
into between three and ten size fractions;
(c) separating a first portion of impurities comprising
shortite from each of said fractions by subjecting each
fraction to a density separation method selected from
the group consisting of air tabling and dry jigging; and
(d) recovering trona.
17. A process, as claimed in claim 16, further comprising: 15
(e) electrostatically separating a second portion of impurities
from each of said fractions, said second portion
being more electrically conductive than trona.
UNITED STATES PATENT AND TRADEMARK OFFICE
CERTIFICATE OF CORRECTION
PATENT NO. . 5,470,554
DATED November 28, 1995
INVENTOR(S) : Schmidt, et. al.
It is certified that error appears in the above-indentified patent and that said Letters Patent is hereby
corrected as shown below:
Title page, item [54] and col. 1, line 1, delete "BENEFICATION" and insert
therefor --BENEFICIATION--.
Columns 31-32, Table 11. 2, line 25 , please delete "<12.3
SG" and insert therefor --<2.3 SG--.
Columns 33-34, Table 11. 2 - continued, line 5, please
delete "<12.3 SG" and insert therefor --<2.3 SG--.
Signed and Sealed this
Seyenth Day of~lay, 1996
Attest:
BRl'CE LEHMA~
Attesting Officer