4,283,277 Beneficiation of trona by flotation

Patent Number/Link:

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

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

ITHICKENER OVERFLO':! - TAIL ING PONDI

UNDERFLOW

, OVERFLOW

I FILTER FILTRATE - IUNTREATED BRINE STORAGE I

ACTIVATED

CARBON

• 1

ICALCINER

FINES TO I BRINE TREATMENT I DISSOLVER

1 ,

\COOLER! -- RECYCLE BRINE STORAGE I

(-C-O-);

and

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

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,

4,283,277

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.

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

1.0

0.0

Amounl

Lbs./Ton

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

Compound

Number

·Solution without a flotation agent.

4,283,277

CHz-C"ONa

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

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

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

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 .

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

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

CH2-C

I .~ONa

CH-C

I ;;-ONa S02Na 0

II I II

ClsH37-N-C-CH2-CH-CONa.

o 0

II II

C12H2S-0-C-CH2-CH2-C-OH.

* * * * *