United States Patent [19]
Brison et at
[II]
[45]
4,283,277
Aug. 11, 1981
6 Claims, 1 Drawing Figure
Primary Examiner-Robert Halper
Attorney, Agent, or Firm-Edwin H. Baker
A froth flotation method for the separation of trona
from ground trona ore slurried in a saturated brine
solution of sodium carbonate and sodium bicarbonate
by using organic compounds of a specified type as flotation
collectors.
[54] BENEFICIATION OF TRONA BY
FLOTATION
[75] Inventors: Robert J. Brison; John C. Gathje,
both of Arvada, Colo.
[73] Assignee: Stauffer Chemical Company,
Westport, Conn.
[21] Appl. No.: 34,527
[22] Filed: Apr. 30, 1979
[51] Int. Cl.3 B03D 1/02
[52] U.S. Cl. 209/166; 209/10
[58] Field of Search 209/166, 167; 55/73;
23/293 S
[56] References Cited
U.S. PATENT DOCUMENTS
2,211,396 8/1940 Weinig 209/166 X
2,385,527
2,834,430
2,839,192
3,525,434
3,973,734
4,110,207
4,139,481
[57]
9/1945
5/1958
6/1958
8/1970
8/1976
8/1978
2/1979
Menefee 23/293 S
Johnson 55/73
Monson 209/166
Garrett 209/166
Rosan 209/166
Wang 209/166
Wang 209/166 X
ABSTRACT
CRUSHING AND GRINDING
CONC
THICKENER OVERFLOW
UNDERFLOW
FILTER FILTRATE
TAILS
RECYCLE BRINE STORAGE
FINES TO
CALCINER DISSOLVE
TO PROCESS AS REQUIRED
u.s. Patent Aug. 11, 1981 4,283,277
ISTORAGE I TO PROCESS AS REQUIRED
IMINED ORE\ FIGURE I
r
ICRUSHING AND GRINDINGI
COLLECTOR BRINE
AGENT ~ It
/CONDITIONERI
, BRINE I r ,FROTHER
I ROUGHER FLOTATION CELLS TAILS
BRINE CONe CALCINER WATER
~ ~ TAILS FINES
• 1
TAILS , CLEANER I CELLS I DECANT - DISSOLVER I
BRINE CONe F _OCCULANT
+ !7 ,Ir
ICLEANER 2 CELlS~ -lTAILlNG THICKENER I
CONe UNDERFLOW
l?
ITHICKENER OVERFLO':! - TAIL ING PONDI
UNDERFLOW
, OVERFLOW
,
I FILTER FILTRATE - IUNTREATED BRINE STORAGE I
ACTIVATED
1
CARBON
• 1
ICALCINER
FINES TO I BRINE TREATMENT I DISSOLVER
1 ,
\COOLER! -- RECYCLE BRINE STORAGE I
~~
Ir
a
II
(-C-O-);
and
(c) At least one oxo radical (0=) which is bonded to
a carbon atom that is separated from the carbon atom of
a carboxyl group by I, 2 or 3 carbon atoms, a nitrogen
and I carbon atom or a nitrogen and 2 carbon atoms, the
2
It has now been discovered that trona can be effectively
beneficiated by froth flotation using organic compounds
of a specified type as flotation collectors.
A flowsheet for the flotation of trona is shown in
5 FIG. 1. The mined ore is crushed and ground to minus
30-mesh. The grinding may be either wet or dry. The
nominal size range of commercial soda ash is typically
30X 140 mesh. Several options are available for handling
the minus 140 mesh fines. They may be removed
10 from the process prior to flotation; they may remain in
the process and be removed and agglomerated after
flotation; or they may remain in the product to be sold
"as is".
After grinding, the trona ore is slurried in a saturated
brine solution of sodium carbonate and sodium bicarbonate
and mixed with the collector agent in a conditioner.
The trona is then floated in a rougher flotation
stage and cleaned in two additional stages. The cleaner
tails are pumped back to the feed end of the preceding
stage. The froth product in each case should preferably
flow by gravity to the following stage to minimize size
degradation by pumping. A small amount of frother is
added to the flotation section.
The final flotation concentrate is pumped to a
thickner to partially debrine the concentrate. The thickener
underflow is either filtered or centrifuged, then
calcined, and cooled.
Nearly all of the brine is recycled. However, some
brine leaves the flotation system via the filtered concentrate
and the tailings. The only unrecoverable brine is
that which is retained in the tailing pond with the settled
solids.
The make-up brine for the flotation system is prepared
by agitating the flotation tailing, calcined fines,
tailing pond decant, and water in a dissolving tank. The
brine preferably contains approximately 18 grams (g)
NazC03 and approximately 4 g NaHC03 per 100 g
brine. The dissolving tank overflows to the tailing
thickener. Flocculant may be added to aid the separation
in the thickener. The thickener underflow is discharged
to the tailing pond and the overflow is sent to
the untreated brine storage tank. Brine from this tank is
treated with activated carbon to remove organics resulting
from the dissolution step, then transferred to the
recycle brine storage tank. The concentrate thickener
overflow and filtrate is also added to this tank which
supplies brine to the process.
Generally, the method of this invention for the froth
flotation separation of trona from ground trona ore
slurried in a saturated brine solution of sodium carbonate
and sodium bicarbonate comprises floating the trona
from the slurry using as a flotation collector an organic
compound which contains the following essential constituents:
(a) At least one non-polar hydrocarbon group containing
a total of at least .10 carbon atoms;
(b) At least one polar carboxyl group,
65
4,283,277
1
NaC03.ZCaC03
NaC03·NaHC03.ZHZO.
BENEFICIATION OF TRONA BY FLOTATION
The major impurities occur in the irregular seams
which are commonly termed "oil shale", more accurately
these can be described as marlstone rich in or- 15
ganic matter, approximately 4% of the ore as mined is
the mineral shortite,
BACKGROUND OF THE INVENTION
Trona is a naturally occurring ore found in the area of
Green River, Wyoming and Kenya, Africa. Crude
trona, for example, from the state of Wyoming consists
of about 90% sodium sesquicarbonate
which is relatively insoluble in water and is always 20
associated with the oil shale. The crude ore also contains
organic matter which is found in the sodium sesquicarbonate
and oil shale. Iron,' present mostly, as
pyrite, vanadium, chromium and other heavy metals are 25
also present as minor impurities, mixed with about 4%
to 6% insoluble impurities which are largely silicates
and contains small amounts of iron, sulfates, chlorides,
etc. A typical reported trona analysis is 45.11% Naz.
C03, 35.75% NaHC03, 15.32% water, 0.03% NaCI, 30
0.01% NazS04, 0.11% Fez03 and 3.75% insolubles.
However, the analysis will differ depending upon the
location in the mine from which the trona is removed,
some portions carrying larger or smaller percentages of
insolubles and other impurities. 35
Two basic processes have been used commercially in
the processing of the ore.
One process dissolves the sesquicarbonate as such,
treats the solution to remove insolubles and organic
matter, and then crystallizes sodium sesquicarbonate 40
which may be used as such or calcined to soda ash. The
resultant soda ash is pseudomorphic in form after the
crystal pattern of the sodium sesquicarbonate, and special
additives are needed to get desirable crystal properties.
Moreover, the crystal structure is different from 45
that obtained by the conventional Solvay process, so
that the product is sometimes difficult to substitute for
conventional Solvay process soda ash. Processes of this
type are disclosed in U.S. Pat. Nos. 2,346,140; 2,639,217;
2,798,790 and 3,028,215. 50
The second basic process for handling natural trona,
the so-called monohydrate process, produces a product
which is like Solvay process soda ash. In this process,
the trona is first calcined to crude soda ash; the ash is
dissolved, and the solution treated to remove insolubles. 55
The resultant solution is crystallized to produce sodium
carbonate monohydrate crystals, which are then treated
to remove the water of hydration and produce soda ash.
Process of this type are disclosed in U.S. Pat. Nos. 60
2,343,080; 2,343,081; 2,962,348; 3,131,996 and 3,260,567.
Each of these processing techniques involves dissolution,
clarification, filtration and crystallization, with
relatively high energy consumption, adding substantially
to the cost of the final product.
Accordingly, it is an object of the present invention
to provide a relatively simple and inexpensive process
for the production of soda ash from trona ore.
4-
amounts of collector agent increase the percent recovery.
Additionally, the acid-insoluble content of the products
was ascertained by determining what weight per-
5 cent of the materials was insoluble in dilute hydrochloric
acid (13.6% HCl by volume). The mineral shortite,
which is water-insoluble, is not considered an undesirable
impurity in the floated trona product. Therefore,
10 the acid-insolubility determination was selected as a
main basis for evaluation. The percentage of the total
acid-insoluble material collected in the trona concentrate
is also reported in Table I for the collector agent.
Generally, higher overall weight percent recovery in
15 the rougher froth and lower recovery of acid-insoluble
material in the froth indicate higher efficiency for the
collector agent.
The recovery of acid-insoluble material in the froth is
substantially further reduced by two flotation cleaning
20 stages.
Iron was found to be removed by the flotation
method in approximately the same percentage as acidinsoluble
material.
2. A method for the froth flotation separation of trona
from ground trona ore slurried in a saturated brine
solution of sodium carbonate and sodium bicarbonate
comprising flotating the trona from the slurry using as
the flotation collector a compound having the structural
formula
3. A method for the froth flotation separation of trona
from ground trona ore slurried in a saturated brine
solution of sodium carbonate and sodium bicarbonate
comprising flotating the trona from the slurry using as
the flotation collector a compound having the structural
formula
What is claimed:
1. A method for the froth flotation separation of trona
from ground trona ore slurried in a saturated brine
solution of sodium carbonate and sodium bicarbonate
comprising flotating the trona from the slurry using as
the flotation collector a compound having the structural
formula
61.3 34.6
92.3 35.1
90.1 36.6
73.4 37.3
83.0 32.2
70.6 39.5
8.2 14.5
Overall WI. Acid Insol.
(%) (%)
TABLE I
3.0
4.0
2.0
2.0
2.0
1.0
0.0
Amounl
Lbs./Ton
o
II
H H COH 0
I I I II
C14H29-C=C-CH--CH2-COH .
H 0 S02Na
I II I
ClsH37-N-C-CH2CH--CONa.
TESTING OF TRONA FLOTATION AGENTS
Recovery in Rougher Froth
1
2
3
4
5
6
Compound
Number
·Solution without a flotation agent.
30
25
4,283,277
o
~
CHz-C"ONa
o
~
CH-C
I 0 "ONa SOzNa 0
II I II
ClsH37-N-C-CH2-CH--CONa
H 0 S02Na 0
I II I II
ClsH37-N-C-CH2-CH--CONa
o
II
H H COH 0
I I I II
CI4H29-C=C-CH-CH2-COH
o CH3 0
II I II
CIIH23-C-N-CH2-C-OH
o CH3 0
II I II
C17H35-C-N-CH2-C-OH
o 0
II II
C12H25-0-C-CH2~CH2-C-OH
6
2
4
Compound
Number
FLOTATION TESTS
Trona ore from the area of Green River, Wyoming 35
was crushed to approximately minus six mesh. A 500 g
sample of this crushed ore was wet ground in a laboratory
rod mill (8" longX8" diameter) for I to 2 minutes.
During this wet grinding operation, a saturated solution
derived from trona ore and having organic material 40
removed was used as the flotation medium.
Next during the conditioning stage, the 500 g sample
of the wet ground ore was placed in a Wemco ® laboratory
flotation cell, size 600 g. The conditioning consisted
of adding a collector agent to the wet ground ore 45
sample and then mixing the treated sample by running
the rotor of the flotation cell at about 900 r.p.m. for
about 3 to 9 minutes at ambient temperature without air
being introduced into the sample. During the last 10 50
seconds of this conditioning, a small amount of a frother
agent, such as Dowfroth® 250, was added to the sample.
Next during the flotation stage, the flotation cell" was
run with air being introduced into the sample. 55
The introduced air rises through the pulp to the top
surface to form a froth. Trona treated with an operative
collector agent attaches itself to the rising air bubbles
and rises to the top of the cell. The trona then overflows
or is skimmed from the top surface as froth into a col- 60
lecting vessel. The flotation stage was run until a nonmineralized
froth was obtained generally from 5 to 10
minutes and on the average about 8 minutes.
Next, the floated trona ore was debrined and weighed
and the percent recovery of this rough froth and the 65
overall weight percent collected were calculated. This
overall weight percent collected for various collector
agents is reported in Table I. Generally, greater
3
remaining bond of said nitrogen atom being substituted
by either hydrogen or lower alkyl.
Compounds of the specified type include, for example,
those having the structural formulas:
o CH3 0
II I II
CllH23-C-N-CH2-C-OH .
6
5. A method for the froth flotation separation of trona
from ground trona ore slurried in a saturated brine
solution of sodium carbonate and sodium bicarbonate
comprising flotating the trona from the slurry using as
5 the flotation collector a compound having the structural
formula
4,283,277
5
4. A method for the froth flotation separation of trona
from ground trona ore slurried in a saturated brine
solution of sodium carbonate and sodium bicarbonate
comprising flotating the trona from the slurry using as
the· flotation collector a compound having the struc- 10
tural formula
6. A method for the froth flotation separation of trona
from ground trona ore slurried in a saturated brine
solution of sodium carbonate and sodium bicarbonate
15 comprising flotating the trona from the slurry using as
the flotation collector a compound having the structural
formula
o
~
CH2-C
I .~ONa
~
CH-C
I ;;-ONa S02Na 0
II I II
ClsH37-N-C-CH2-CH-CONa.
20
o 0
II II
C12H2S-0-C-CH2-CH2-C-OH.
* * * * *
25
30
35
40
45
50
55
60
65