Acid leach resin-in-pulp pilot plant testing of Monticello Blend ore

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WIN-70

Metallurgy-Raw Materials

TOPICAL REPORT WIN-70

ACID LEACH RESIN-IN-PULP PILOT PLANT TESTING

OF MONTICELLO BLEND ORE

J@CtA

w.n.

Charles

~

_{H.E. Gardner}

By

A.W. Griffith

M.A. Peters

W.D.

Charles

H.E, Gardner

Marah 28, 1957

TECHN1CAL U~RARY

Grand Junctlcn Operations Offltl

A.E.C. 11 12 1 10,'\ll;<,z

9.:~~3

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,,,\\~ 4

7 6

..J MAY 28 1S51 RECElVED

.s.

Breitenstein

Technical Director

Contract AT(49-6)-924

NATIONAL LEAD COMPANY, INC,

Raw Materials Development Laboratory

Holton Street

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ABSTRACT WIN-70 3

-Uranium ore· from the Monticello, Utah, st'ockpile consis.ting of 40 per cent S.tockpile 68, 40 per cent Stockpile 56, and 20 per cent Stockpile 30 was treated in the Acid Leach - Resin-In-Pulp Pilot Plant at Grand Junction, Colorado, from June 15 through August 31, 1956. The name Monticello !llend was given the above mixture. This report presents.' information on leaching, ion exchange, solvent extracJ;ion .of pregnant elhate, precipitation, and tailing neutra:l:ization tests obtained while treating Monti- . cello Blend. From the pilot plant tes.t ,' i t was concluded that the ore is amenable to the Resin-In-Pulp process.

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TABLE OF CONTENTS INTRODUCTION SUMMARY PROCESS DESCRIPTION A; Grinding B. Leaching

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Sand-Slime Circuit

D. Resin-In-Pulp Adsorption Units E.· Solvent Extraction (Eluex Process) F. Precipitation and Eluant Make-up

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TEST WORK - MONTICELLO BLEND

A. Grinding B. Leaching

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Sand-Slime Separation D. Resin Adsorption E. Elution

F. Solvent Extraction (Eluex) G. Precipitation H. Tailings Neutralization I. Metallurgical Balance APPENDIX

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5 6 8 8 12 12 13 14 15 15 20 20 24 25 35 35 40 42

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INTRODUCTION WIN-70 5

-At the request of the Raw Materials Division of the U.

s.

Atomic

Energy Commission, ore from stockpiles in Monticello, Utah, designated Monticello Blend, was treated in the Acid Leach -Res.in-In-Pulp .Pilot Plant at Grand Junction, Colorado.

Tes.t work in the pilot plant was started June 15 and concluded

August 31, 1956. The test was .conducted to obtain amenability

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SUMMARY

Pilot plant test results from a run on 405 tons of ore from the Monticello Stockpiles showed that the material was :amenable .to

the Acid Leach Res in- In-Pulp process. The mate.rial contained 40 per cent St:ockpile 68, 40 per cent Stockpile 56, and 20 per cent Stockpile 30 and was designated Monticello Blend. Average grade nf the mixture was 0.317% U3o8 •

Average leach extraction for the entire run was 96.3 per cent. The leach tests showed that 97.7 per cent of the uranium could be extracted from a SO per cent solids pulp at ambient

tempera-ture. Prior to leaching, the ore had been ground to 1 per cent

plus 28-mesh. Neither lime nor iron was required to adjust the pulp to the desired pH or emf Values necessary for ion exchange. The data obtained indicate the leach reagent requirement necessary .to obtain a leach extraction of greater than 97 per cent was

240 lb H2so4 and 5.0 lb Mh02 per ton of ore.

The sand-slime circuit was operated to produce an ion exchange

f~ed pulp containing the minus 325-m~sh solids of 1.07 density.

The soluble loss was only 0.03 per cent of the uranium :in the mill feed.

The ion exchange circuit was operated with seven banks on ads.orption, six banks on elution, and one bank as stand-by.

Rohm & Haas XE-123

l/

resin was used in 12 banks and Dowex-11

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was. used in the remaining two. Both resins are strong base anion exchangers and both efficiently adsorbed uranium from the ion

exchange feed. Over~all ion exchange recovery was. 98.9 per cent.

Adsorption recbvery, when eluting with 1.0 ~H₂so_{4 .average.d 99,7}

per cent and averaged 98.5 per cent when using 0.8 ·~ H2S04. The

average figure with 0.8 ~ _{H2S04 is not optimum. Twice during}

the tes.t period and while eluting with 0.8 ~ _{H2so4 , neutralized}

tailing water was· returned to the acid plant circuit and in each case had an adverse effect on the ion exchange efficiency. The adsorption recovery when using fresh water throughout the

circuit and 0,8 ~H₂so

₄

for elution averaged_ approximately

99.5 per cent. Elution with either 0.8 ~ or 1

!1

_{H2so4 was}

satisfactory when tailing water was not recycled,

This does not':·con~t!;J,.trute ·.an. e.ndorsem,e.nt of ·these resins nor ..

. does it mean they ·are the only res :ins applicable to the RIP process

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WI~-70

7

-The solvent extraction of pregnant H₂

so

4 eluate was divided into two test ·periods" _{In the first perio.d the pregnant H2}

so

₄ eluate was extracted by a so). vent consisting of 0.3 ~ di-2- ethyl hexyl

phosphor:lc acid (EHPA) and 2.5 per cent primary d.ecyl alcohol

v/v (PDA) dissolved in ker·osene in a pulse column, whereas in the second period mixer•settlers were employed. In both cas.es mixer-settlers. were .used to strip the uranium. from the pregnant organic into a barren Na2

co

3 solution. The over-all extraction recovery when using the pulse column was 96.7 per cent, whereas the extraction when using mixer-settlersaveraged 99.8 per cent, Average extraction for the enti.re run was 97.72 per cent.

Average stripping extraction for the entire run was 92.17 per cent.

Over-all recovery of uranium for the run was 93.67 per cent with an unaccountable loss of 0.56 per cent.

At optimum leach, ion exchange, and solvent extraction conditions, a total recovery of 95 per cent could.be expected.

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PROCESS DESCRIPTION

A detailed description of the flowsheets and process equipment used in the Acid Leach RIP Pilot Plant has been reported pre-viously,

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The fundamental chemistry of the Eluex process has been described in the Topical Report WIN-28.

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The flow-sheets are shown in Figures 1, 21 and

J,

and are briefly

described below,

A. Grinding

The ore as received from the Feed Preparation Plant is minus 1/2 in, and is fed to a Jx5-ft ball mill in closed circuit with a 24-in. spiral classifier, Water is added to maintain a pulp density of 1,5 to 1.6 ~ in the grinding circuit and 1.44 in the classifier overflow,

B. Leaching

The classifier overflow is pumped to the first of five 5x5-ft mild steel rubber-lined tanks which have Devereaux-type

agitators, An additional 5x5-ft steam-heated tank is avail~

able if a hot leach is required or steam may be added to the fir~t tank, Sulphuric acid is metered into the first tank to give the desired terminal pH in the fifth tank, When

necessary an oxidant is added on the feed belt. Hydrated lime may be added to the last leach tank to adjust the pH for ion exchange, Powdered iron may also be added at this point to reduce plus 5 vanadium to plus 4 vanadium,

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Topical Report WIN-171 Initial Operation of New Acid Leach RIP Pilot Plant. by C, K. McArthur, et al, · g/ Solvent Extraction of Acid RIP Pregnant Eluates, by

W, D. Charles and H. E, Gardner, National Lead Co., Inc., Grand Junction, Colorado, September lJ, 1956

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Topical Report WIN-281 Solvent Extraction of Uranium

from Sulfuric Acid Eluates, by H. G. Petrow, K. P. Quinlan, H, N. Marenburg, and J, C. Apidianakis

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GRINDING

*

WHEN REQUIRED (\, _•,

LEACHING

ION

EXCHANGE

Figure I

DESANDING

.f"') ~SANDS Tallinga) Eluant Make np

I JPIIIIIIIIII!

lei

I . . BLEED

*

1 (To Tailings)

YELLOW

CAKE

PR EC I PITA Tl 0 N

ACID LEACH-RIP PROCESS

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\Oz

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PULSE COLUMN EX FRACTION PREGNANT ORGANIC STRIPPING Figure 2

PREGNANT ELUATE SOLVENT EXTRACTION PROCESS

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f-'Z

O.!.:J

1 0

,~-\ ( \ EXTRACTION STRIPPING STEAM

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' TO ACID LEACH Figure 3

PREGNANT ELUATE SOLVENT EXTRACTION PROCESS

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PRECIPITATION YELLOW CAKE I~ f-'Z f-'~ 1 0

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C. Sand-Slime Circuit

The pulp from the las.t leach tank discharges into the first of four 22-in. Esperanza-type drag .classifiers constructe.d of type 304 ·stain:les.s steel. The classifiers are operated to produce a minus 325-mesh slime product, The density of the slime overflow is held at LOS to 1.08 by controlling the water

added to the las.t classifier, Sands are .washed countercurrently and two 2-in, porcelain Dorrclones are used to scalp the .tramp oversize from the overflows of the first and se.cond classifiers. The dilution of the leach pulp in the sand-slime s.eparation circuit rais.es the pH of the slime product to 1.4 to 1.7, a range suitable for ion exchange. Washed sands are dis:charged to tails.

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Resin-In:-,Pulp Adsorption Units

There are 14 ion .exchange banks, each bank consisting of a tank baffled into. two compartments. Each compartment contains an 18-in. baske.t which is moved slowly up and down while pulp or solution flows slowly through the bank, Each basket holds 1.1 cu ft of wet settled plus 20-,mesh ion exchange resin. The 28x8-mesh screen used for the baskets. permits 'pulp flow and retains. the resin. Flow of pulp or eluate through the baskets is .by displacement and air lifts provide flow between bimks. Normally, seven banks are on the loading or ·adsor,Ption cycle, six are on elution, and one ban:k is a spare. Slime product from the sand-slime separation c.i.rcuit is fed to the first bank on. exhaustion. When the resin i.n the bank reaches a des.ired

u

₃

o

8 loading, ion. exchange feed is advance.d to the next bank and the spare bank then becomes the last bank on ads.orption. Pulp from the last bank on adsorption goes to tailings. The loaded bank, which was. removed from the adsorption .cycle, is washed free of pulp and be.comes the last bank on elution. Made-up eluant is fed to the first bank on elution imd pregnant eluate from the sixth, or last bank, goes to precipitation or solvent extractio.n. Although the resin remains fixed in any one bank, the manner in which

feeds ·are advanced from bank to bank produces a countercurrent effect. The time at which a bank is removed from or added to the circuit is called "changeover" ·and is calculated from the feed rate, uranium content, and desired or possible resi.n loading.

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E. Solvent Extraction (Eluex Process)

WIN-70 13

-The extraction of uranium from a sulphuric acid pregnant eluate into a barren commercial solvent is accomplished by contact between solutions in either a 23-ft pulse column or in separate mixers and settlers. The two methods of contacting are described below.

The pulse column is a 4-in. ID 316 stainless steel pipe con-taining 115 stainless steel sieve plates separated by 2-in. spacers, Each sieve plate has approximately 180 1/8-in. holes. Pyrex tees are flanged to each end of the pipe to facilitate observance of flows, interfacial relations, and phase disen-gagement in the sieve plate area. A pipe from a 3 hp pulsator extends up into the bottom of the column approximately 18-in. The pulse column is· operated with the organic as the continuous phase, The interface is located in the bottom of the column just below the stripped organic inlet and is controlled at a preset level by a photoelectric device coupled to a pneumatic valve located on the raffinate discharge.

Five stages of mixer-settlers may be substituted for the pulse column in the extraction step. The equipment is arranged in tw.o rows, the mixers in one row and the settlers in another. The mixers and settlers are 347 stainless steel tanks 11 inches in diameter and 12 inches high. The mixer of the first stage is 2 .inches above the settler for that stage and the mixer of the second stage is on the same level as the first settler, etc. Air lifts are provided for advancing the aqueous phase from the

settler to the next higher mixer whereas the organic overflows the settler and advances to the next lower mixer by gravity. When using either the pulse column or the mixer-settlers, raffinate is returned to the leach circuit.

Four stages of mixer-settlers are used in the stripping circuit· for the purpose of stripping the uranium from the pregnant organ·ic into a ba.rren 10% Na2C03 solution. The mixers· of the stripping circuit are 8-in. ~ by 14-in. high cylindrical tanks .constructed o.f 316 stainless steel. The settlers are 10-in. ID by 9-1/2 in. high with sight glasses for visual interface control. Internal baffles are incorporated to control overflow at eight inches above the base of the 45° cone bottom. The mixers and settlers of the stripping .circuit are arranged in a similar manner as those of the extraction cir.cuit.-·· Pregnant carbonate flows· from,· the settler of the first or' top stage, while stripped organic overflows the settler of the fourth stage and is returned to the extraction step for re-use in the pulse column or extraction mixer-settlers. Pregnant carbonate from the first stage is pumped to precipitation.

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F. Precipitation .and Eluant Make-up

Pregnant eluate t:rom the RIP unit or pregnant carbonate from .the Eluex

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circuit flows ·to two 6x6-ft rubber·l~ned tanks for batch precipitation. The precipitate is filtered in .a plate and frame

filter press, the cake is washed with water, and the wash is discarded. The yellow cake is .dried in ·.a .. gas.-fired drier, barreled, sampled, and shipped.

When NH4N()₃ is us.ed as. the eluting s.olution, the uranium is pte,.· .. cipitated oy neutralization, i;·e,, raising the pH to 7.0 with either MgO or ammonia. Wit;h MgO precipitation, 10 to 12 per cent of the barren filtrate is bled to tails and the balance is recirculated as make'"up eluant. The bleed is. r.equired to prevent .a build-up of s~lts and subsequent crystallization. With ammonia precipitation, little .or no bleed is required. Eluant .is m_ade up to 0.9 ~ _{NOj"with NH4No3 and the pH is} adju~ted .to 1.0 to 1.2 with H2S04 before recirculation.

When solvent extraction of pregnant eluate is added to the flow-sheet, the eluting solution used is 0 .8 :~ to 1.0 ~ H2S04. The feed to precipitation is no longer ·a low-grade acid_ s.olution but instead becomes a high-grade (50 to 70 g

u

₃

o

_{8;1) carbona.te} solution, Uranium precipitation is .accomplished by first lowering the pH to 2.5 to 3.0 with H2

so

4 to drive off the C02 'and then neutralizing with either MgO or NaOH. Each batch of eluant is made up with fresh water.

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TEST WORK - MONTICELLO BLEND

WIN- 70

15

-A summary of operational data from the Monticello Blend run is presented in Table I. During the run, 405 tons of ore was processed at approximately 6 .1 dr:{"tons· per: day. The average

leach extraction was 96.3 per cent. A. Grinding

Ore fed to the ball mill had been crushed previously to minus 1/2 in. and averageti 0.317%0308. The ore was ground in suf-ficient water to give a ball mill discharge density of 1.65. The ball mill classifier overflow was maintained at 50 per cent solids resulting in a grind of 0.97 per cent plus 28 mesh and 49.99 per cent minus 325-mesh. The minus 325-mesh fraction contained 57.95 per cent of the uranium. Daily grinding and leach data are presented in Appendix Table 1. Screen analyses of the ball mill feed and the classifier overflow are presented in Appendix Tables 2 and 3.

B. Leaching

Daily leach data are presented in Appendix Table 1. For the purpose of simplifying the explanation of results, leach data are divided into the six test periods shown in Table II. During tests 1, 2, 4, and 6 raffinate from the Eluex circuit was returned to the leach circuit, During periods 3 and 4

the raffinate was sent to tails and neutralized tailing water was returned to the head of the leach circuit replacing an equivalent amount. of fresh water.

At the start of the Monticello test, 2000 gallons of raffinate remained in storage from a previous amenability test. The stored raffinate was returned to the leaching circuit during the first two days of test 1 at a flowrate of 0.6 gpm, a rate greater than the flow from the Eluex circuit. A total of 6.08 tons of ore assaying 0.293% U30s was treated during this test. The leach residue averaged 0.012% U308 which resulted in a leach extraction of 95.9 per cent. Acid con-sumption was 219.7 lb H2S04/ton of which 128 lb was fresh acid and 91.7 lb was acid obtained from the raffinate. Leach

condition~ were: density 1.35, terminal pH 1.2, emf minus 373

mv, and retention time 26 hours.

During the second leach test raffinate was returned to the

leach circuit intermittently; however, the average flow for the period was 0.32 gpm. Oxidant was added at a rate of 5.0 lb Mn02/ton. Because of the change in raffinate volume a direct

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Table I

Summary of Pilot Plant Data Monticello Blend

Grinding and Leaching Total tons milled

_Ore feed rate, tons/day Leach contact time, hr

Ore feed assay, % U308

Acid addition, lb H2so4/ton Terminal pH of leach

Terminal emf of leach, mv

Residue assay, % U308

Leach extraction, %

Sand-Sli~e Separation

Sand tails solution assay, g U308/l Adsorption

Adsorption unit feed, density gpm/ton/day pH

emf, mv

g

u

₃

o

_8;1

Ads,orption unit tails, g _U3o811

Adsorption-unit recovery, %

Ghangraover' time, hr Elution

Gallons eluant/bank eluted, LO ~ _H2so4

_ 0.8 ~H

₂

so₄

Pregnant eluate, g u_{3o8 , 1.0} ~ H2S04

o.8 ~ H

2

~o

4

405 6.1 26 - 39 0.317 195 - 257 1.2 -393 0.012 96.3 0.007 1.07 0.66 - 0.73 1.5 -393 0,706 - 0.932

o:oo3 -

o.o11 98.5 - 99.7. '3 .46 - 4. 90 95 119 7.8 5.93

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WIN- 70

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-Table II

Leaching Date - Acid RIP Pilot Plant Monticello Blend

Ambient Temperature

Test

Head assay, %

u

_3o8

Tons treated

Feed rate, ton/day

Oxidant, lb Mn02/ton H2S04 Consumption~ lb/ton Total acid Fresh acid Raffinatelf Contact time, hr Leach density Terminal emf, mv Terminal pH

Residue assay, % U308 Extraction, % 1/ Calculated as 96% H2so4 ~/ Calculated assay 1 2 0.293 0.418 61.08 54.94 6.11 6.10 none 5.0 219.7 224.1 128 177 91.7 47.1 26 26 1.35 1.39 -373 -389 1.2 1.2 0.012 0.013 95.9 96.9

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4 5

_&.

0.440 0.302 0.270 0.282 30.24 110.77 50.10 79.70 6.05 4.10 6.26 6.13 5.0 5.0 5.0 5.0 240 257 237 195 240 257 . 188 122 none none 49 73 26 39 26 26 1.47 1.47 1.39 1.39 -389 -393 -404 -406 1.1 1.1 1.2 1.2 0.010 o.o1o11o.o1o1/o.014 97.7 96.7 96.3 95.0

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comparison of the benefit of MnO ,addition could not be made. Feed

to the leach circuit averaged 0

.~18'7.

_{U308 and the leach residue}

averaged 0.013% U308 resulting in a leach extraction of 96.9 per cent. Leach density during the second p.eriod averaged 1. 39, the terminal pH averaged 1.2, the emf averaged minus 389 mv, and the

retention time was 26 hours. The total acid consumption was

224.1 lb H2so4 per ton of ore of which 177 lb was fresh acid and 47.1 lb was raffinate.

During the third leach test the use of raffinate in the leach circuit was discontinued and the addition of 5.0 lb Mn02/ton of ore was continued. The leach density averaged 1.47, the pH 1.1, the emf minus 389 mv., and the retention time 26 hours. Acid consumption was 240 lb H2so4/ton of ore. The feed to the leach circuit averaged 0.440% U3o

8, the leach residue averaged 0.010%

u3o8,and the leach extraction was 97.7 per cent.

During test 4 the ion exchange tails were neutralized with hydrated lime and the tailing water was returned to the leach circuit. The raffinate, normally returned to the leach circuit, was stored, sampled, and discarded, The leach residue as reported in Table II is a calculated figure obtained from the flowrates and assays of the neutralized slimes and the No. 4 drag classifier

sands. The u_{3o8 content of the leach feed dropped to 0.302%}

during this period while the calculated tails remained at 0.010% U308 resulting in an extraction of 96.7 per cent. The acid con-sumption was 257 lb Hzsp

4/ton of ore. The increase in acid

con-sumption in test 4 was probably the result of increasing the ~.

leach contact time from 26 to 39 hours. The leach density

averaged 1.47, the pH 1.1, and the emf minus 393 mv. Oxidant

addition was 5.0 lb Mn02/ton of ore.

Tailing neutraliz:ation continued during test 5 and raffinate from the Eluex circuit was returned to the leach circuit. The leach retention time was again 26 hours. The leach dens.ity

averaged 1.39, the pH 1,2, and the emf minus 404 mv. Feed to

the leach circuit averaged 0.270% u3o8 • The calculate.d tails

averaged 0.010% u₃

o

₈ which gave a leach extraction of 96.3 per

cent. Total acid consumption was 237 lb H2S04 /ton of which 188 lb was fresh acid and 49 lb was acid obtained from the raffinate. MnOz addition was maintained at 5.0 lb/ton of ore. Daily residue assays during the neutralization period are shown in Table III.

Ra:ffinate was returned to the leach circuit during test 6; however, tailing neutralization was discontinued and fresh water was used

throughout the circuit. The feed to .t~e leach circuit averaged

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WtN-70 19

-95.0 per cent. The leach density averaged 1.39, the terminal pH

l. 2, the emf minus 406 mv, and the retention time was 26 hours.

Mh02 addition of 5.0 lb/ton of ore was continued. Acid consumption was 122 lb fresh H2so4 and 73 lb raffinate H2so4 per ton or a

total cons.umption of 195 lb H2S04/ ton of ore.

Table III

Tailings During Neutralization Test Period - Acid RIP Pilot Plant . Mont.icello Blend

July 30 - August :16., 1956

No. 5 Drag Thickener

Date Leach Tank Sands U'flow

1956 % U309 % U308 % u3o8

7-30 0.017 0.005 0.016 7-31 0.011 0.003 0.019 8-l 0.012 0.002 0.018 8-2 0.012 0.004 0.014 8-3 0.020 0.004 0.015 8-4 0.015 0.005 0.015 8-5 0.019 0.004 0.016 8-6 0.012 0.004 0.016 8-7 0.019 0.005 0.014 8-8 0.031 0.017 8-9 0.006 8-10 0.017 0.005 0.019 8-ll 0.03 0.005 0.019 8-12 0.013 0.005 0.018 8-13 0.014 8-14 0.012 0 •. 006 0.022 8-15 0.014 0.006 0.023 August 0.016 o.qo5 0.017 Operating Conditions

Ball mill feed rate: 5;18 tpd

Drag s.and flow rate: 2.99:tpd

Adsorption flow rate: 2.19 gpm

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Optimum leach conditions of .those studied appear to be those of test 3; viz, 240 lb H2so4 and 5.0 lb Mn02 per ton, a leach pulp density of 1.47 and with 26 hours retention· time· .which resulted in.a leach residue of 0.010% UJOa.

C. Sand-Slime Separation

The sand-slime circuit was operated to provide an ion exchange feed pulp having a density of 1.07, or 8.9 per cent solids. The s.olution discharging with the No. 4 drag classifier sands.

averaged 0.007 g U30a/l which resulted in a soluble loss of 0.03

per cent of the U30a in the mill feed. Screen analyses of the

sand-slime circuit are presented in Appendix Tables 4 and 5.

D. Resin Adsorption

Throughout the test seven ba11ks were used on adsorption, six banks on elution, and one on stand-by. Twelve of the banks

contained Rohm

&

Haas XE-123 resin and two banks contained

Dowex-11 resin. Both are strong base anion exchange resins. The ion exchange test work .on pulp produced from the Monticello Blend is divided into two periods, one discussing operation

while eluting with 1.0 ~ _{HzS04 and the second covering operation}

while 0.8 ~H₂so4 was us.ed as the eluant. Daily ion exchange

da.ta are presented in Appendix Table 6 and a summary of data

for the two periodsis shown in Table IV. Over-all ion exchange

recovery for the entire run averaged 98.9 per cent.

During the period of 1.0 ~H2So

₄

elution (J~ne 15 through.

July 9, 1956) the adsorption feed averaged 0.932 g U3Ds/l

and the adsorption tails 0.003 g

u

_{3o811 resulting in a}

rec.overy of 99.7 per cent. The . intended res in loading was 2.72 lb U308/cu ft WSR, .. the fLowrate of the ion exchange feed pulp averaged 0 .66 gpm/tpd, the pH averaged 1.5, and the <emf

minus 382 mv. Total pulp to resin contact time averaged 146

minut.es and changeover or cycle time averaged 3.46 hours. Fresh water was used throughout the grinding, leaching, sand-slime, and .adsorption circuits, and no difficulty was encount-ered in the ion exchange circuit during this_period of operation.

On JU!ly 10, 1.0 ~ _{H2so4 eluant was replaced with 0.8} .~ _H2S04

eluant. While operating with 0.8 ~ _{H2S.04 as the eluant and}

using fresh water throughout the entire plant circuit ion

exchange tails ranged between 0.002 and 0.006 g

u

_{3o 8/1} ~ith

an intended res.in loading of 2.45 lb

u

₃

o

_{8 /cu ft WSR.} However,

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Table IV WIN-70 21

-Ion Exchange .Data - Acid RIP Pilot Plant Monticello Blend

Eluant 1.0 M H2S0

4 0.8 M H2S04

Ads.orption

Adsorption feed, g

u

_3o8/l 0.932 .0.706

gpm 4.06 3.64 gpm/tpd 0.66 0.73 pH 1.5 1.5 emf, mv -382 -404 density 1.07 1.07 Banks 7 7

Total contact time, min 146 163.5

Cycle time, hr 3.46 4.90

IX tails, g u₃o~/l 0.003 O.Oll

u

_3o8 recovery, , 99.7 98.5

Elution

Banks 6 6

Gal eluant/bank eluted 95 ll9

Pregnant eluate, g U3o811 7.8 5.93

Final eluate, g u

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operation and a portion of the tailing·.water, equivaient to 20 per cent of the total mill water, was returned to the mill steady head wa.ter tank. The

so4,

content of the ion exchange feed starte.d to increas.e and immediately the ion exchange tails increased, reaching·a maximum value of 0.08•7." g

u

₃

o

_{8 ;1 on}

July 21. The first theory on the rapid increase in U3.08 content of the ion exchange tails was that the recycle tailing water from the neutralization circuit was affecting adsorption. Accordingly, the tailing water was s.ent to tails on July 18, but the ion exchange tails continued to increas.e. Resin s.trips. for molybdenum indicated a build-up of approximately 0.5 lb Mo/cu ft WSR, an amount normally insufficient to decrease ion exchange efficiency s.ubstantially. However, it was thought that with the adsorption cycles based on an intended resin loading of 2.72 lb U308, 0.5 lb molybdenum on the resin might decrease adsorption efficiency. On July 23 the intended loading was changed to 2.45 lb and three quick changeovers each of two hours duration were made. _{The U3-08 .content of the ion exchange} tails s.tarted decreasing slowly and by July 27 were 0.005

g

u

₃

o

/1. Cycle times based on a. 2.45 lb U3-0

8 loading were used

~or

the remainder of the run. Neutralized tailing water was. again returned to the circuit on August 1 and its use .was continued until Augus.t 15 when again it was sent to tails. On August 11 ion exchange tails increased to 0.007 g

u

_{3o8 /l or} greater and on August 14 reached a high of 0.010 .g U308 /1.

Recovery to normal operation with the discontinuation of tailing water use was. much faster at the 2.45 lb U3o

8 loading than at the 2.72 lb.

Figure 4 contains three graphs by which adsorption efficiency may be compared with the sd,4 content of the ion exchange feed

and with the molybdenum content of the 'e1uted resin . . Two distinct dips in the extraction curve (points. a and b)· are accompanied by both the return of tailing water and an increase in the

§04

content of the ion exchange feed to greater than 20 g SOl;/1. Analys.es. of the neutralized tailing water indicated that the Sd,4 concent:ration was approximately 4 g/1. From the results obtained it appeared that an :s04 concentration in the ion exchange feed of greater than 20 g/1 was harmful to adsorption ·efficiency and that 0.5 to 0.6 lb/Mo. 'au ft WSR was not.

(

(

'--· ( \ (I() 0

_....,

::> toe ~ 95 >, ....

..

s

_u

&

90 87 30 28 26 ... 24

...

(! 22

"'

20 00 18 16 ' ~4 12 p::: ~ 0,8

_,.

0.6

.,_,

0,4 :;:! ~ 0.2

:i'

o.o

' ... ~ ... I ... (a)

---

...

....

'

0 (b) WIN-70 23

-Ion Exchange Recovery

S04~ in Ion Exchange Feed

'

_'

'

_'

' '~

-o--- --.--

--o

--o---o---0- - - - -

--Molybdenum on Eluted Resin

'

....

0

..,

g ...

'?

_~

LAJ ~ N I

....

o-l

rtob

00 00 Date, 1956

I

B

c

D

E

F - - - 1

A - Water from neutralization thickener returned to circuit (20% of total circuit water).

B - Water from neutralization thickener returned to circuit (51% of total circuit water),

C - Intended resin loading, 3,25 lb

u

₃

o

_{8/cu ft,}

D- Intended resin loading, 3,00 lb.U30s/cu ft. E - Raffinate from Eluex circuit discarded,

F - Raffinate from Eluex circuit returned to acid leach circuit, Figure 4

Ion Exchange Adsorption'"Data Acid RIP Pilot Plant July 11 - August 28, 1956

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E. E!1ution

Eluant us.ed un.til July lO Wa:a 1.0 ~ H_{2so4 at a flow of 95 ga:llona}

to precipitation per bank eluted. Final eluates in the lead

bank on elution averaged 0.18 g U305/l and pregnant eluate averaged

7.8 g u_{3o8/l. Acid consumption was 3.88 lb Hzso4 /lb U308 produced}

while eluting with 1.0 .~ HzS04. A portion of this acid consumption

. was required in .the Eluex ·circuit to convert the sodium salt of the stripped organic solvent to the acid form.

On July lO the 1.0 ~ HZS04 eluant was replaced with 0.8 ~ H2S04

eluant. The 0.8 M solution was used for the remainder of the test

period. The vol~e· of pregnant eluate sent to precipitation varied

from 110 to 125 gallons per bank elj!ted, During this. period an

average of 119 gallons of 0.8 ~H₂so

₄

was required which is

equiva-lent to approximately 59.5 gallons of eluant per cu ft WSR.

Satis-factory barren eluates were obtained when using as little as 110

gallons 0.8 ~H₂so_{4 per bank eluted. Final eluates in the lead}

bank ~n elution averaged 0.17 g U30₈11 and pregnant eluates averaged

5.93 g U3o8;1. Reagent figures showed an acid .consumption of 4.21 lb of H2S04/lb U308 produced. Daily eluate analyses are presented

in Appendix Table 7. An elution gradient to determine the amount

. of H2so4 lost in the RIP circuit when using 0.8

.k!

HzS04 eluant was

·. taken August 7 and is presented in Table V.

Table V

HzS0₁₁ Loss During Elution - Acid RIP Pilot Plant

Monticello Blend Eluar!t: . ' ··:· Eluate: Elution cycle: Bank No. lO 11 12 13 14 1 H2S04 in discharge, g/1 after 2 hr 4 hr 6 hr 74.5 73.5 70.8 73.7 74.0 75.0 74.0 74.5 75.0 75.8 75.0 75.5 74.0 74.0 75.5 65.5 69.5 77 .o

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(

WIN-70 25

-These data show that the 1.65 lb H2S04 consumed by the rj'sin per lb U30

8 Was essentially all ;idsorbed in the bank which: had just been put on elution (Bank 1) and that no H2so4 gradient exist·ed·'. the preceeding banks.

The above figures indicate that approximately 40 per cent of the 4.21 lb H

2so4 consumed in elution remained on the resin whereas 60 per cent was used to convert the sodium salt of the barren di-2-ethyl hexyl phosphoric acid to the acid form.

F. Solvent Extraction (Eluex)

Made-up solvent consisted of 0.3 M di-2-.ethyl hexyl phosphoric acid (EHPA) and 2.5 per cent primary d;cyl alcohol v/v (PDA) dis.s.olved in kerosene, whereas the stripping solution was 10% Na2co₃.

A pulse column was used in the e.xtraction circuit at the start of the test but was replaced by five mixer-settler units on October 8. The mixer-settler ·units permitted higher extractions. at greater throughput rates than were possible with the pulse column:. Strip-ping of .the pregnant organic utilized four stages of mixer-settler units but as the test progressed the number was eventually decreased to two stages.

Extraction

Daily extraction data are shown in Appendix Table 8. Extraction for the entire test period was 97.72 per cent.

The solvent extraction pulse column was operated at a frequency of 60 cycles per minute with an amplitude of two inches. Mechanical difficulties were encountered in the extraction circuit as the

result of dreg build-up at the aqueous-organic interface. The dreg, if permitted, accumulated to a depth of several inches, After

accumulating immediately above the pulse pipe, the material behaved . as follows: either it mixed with the emulsion above the interface

and plugged the holes, or a part of the dreg became dispersed in the raffinate and interfered 'with operation of the electric eye. In either cas.e the column .began to flood and became inoperative, A sample of the dreg was s.ent to the Raw Materials Development Laboratory at Winchester, Massachusetts, for analysis and was identified as principally ore slimes.

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The pregnant elu"!te was predominantly green in .color which was imparted to the organic phase on passing through the column. Spot samples of the circuit indica,ted the green color was the result of iron, predominently ferrous., and/or molybdenum.

In an attempt to up-grade the pregnant carbonate solution, the

volume of carbonate strip used in the .stripping units wa,s reduced ,/

excessively resulting in a build-up of U308 in the stripped organic 1 returning to the column. The build-up was intentionally allowed to go unhindere.d for experimental purposes. Before the carbonate strip volume was increased, the U308 content of the stripped organic had reached a value of 8 g U308/l, the pregnant organic assayed

22 ·g U3o8;1, and the pregnant carbonate assayed 67 g U308/1. Although the circuit was. definitely out of balance, the raffinate for this period averaged only 0.32 g U308/1 and the extraction averaged 96 per cent.

Two tests on column operation were studied wherein the total throughput to the column was varied. At a total throughput rate of,423 gal/hr/sq ft of column cross-sectional area, raffinates averaged 0.49 g U30811 and extraction averaged 93.7 per cent. At throughput rates of 359 gal/hr/sq ft, raffinates averaged 0.16 g U30

8/l and extraction averaged 97,6 per cent. Table VI lists t.he column operational data. for the. two tests. The over~all extraction recovery while using the column averaged 96.7 per cent,

On August 2, the pulse column was replaced with five stages of external mixer-settlers. A dreg similar to that which collected

in the column also built up in the settlers. This material had to be removed from the settlers every 4 to 6 hours to prevent plugging of the overflow lines. When allowed to stand several hours most of the organic was decanted from the solids and was returned to the circuit.

Table VII presents the pertinent data obtained on extraction with mixer-settler units. The extraction recovery for the run while

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Table VI

. Eluex :Circuit ·- Mid RIP Pilot l?lant Extraction Data - Pulse .Coli.unn U"nit

Monticello Blend

Tes.t No.

Pregnant eluate, g U308/l Total throughput, ml/min

gal/hr/sq ft Flow ratio, aqueous:organic

Raffinate, g u_3o8/1

Pregnant organic, g U308/l

Extraction, % Table VII 1 7.84 2347 423 l . 99:1 0.49 13.93 93.7

Eluex Circuit - Acid RIP Pilot Plant

E)<traction Data ---Mixer~settler.Uriits

Monticello Blend

Test No. 1 _2_ 3

Eluate, g U308/l 5.80 5.87 5.65

flow, ml/min 1373 1495 2101

Stripped organic, g U308/l 1.36 3.60 0.38

flow, ml/min 743 741 745

Flow ratio, aqueous. :organic 1.85 2.02 2.82

Total throughput, gal/hr/sq ft 51 54 68.4

Raffinate, g U308/l 0.015 0.026 0.005

Pregnant organic, g U3o8;1 13.34 16.49 17.74

Ex!=raction, % 99.7 99.6 99.9 WIN-70 27 -2 6.80 1977 359 1.85:1 0.16 13.93 97 .6. _4_ 5.52 2412 0.64 855 2.82 78.6 0.009 17.63 99.8

(

Stripping

Daily stripping data are presented in Appendix Table 9. The average stripping recovery for the entire run was 92.17 per cent. Four stages of mixer-settlers were used through August 3 for stripping the pregnant organic. Average .data for the period June 19 to July 9 are presented in Table VIII. From July 10 to August 3 the carbonate solution flow was such that an average of 2.3 lb Na2co3 entered the circuit per pound of U308 in the pregnant organic. However, the stripped organic averaged 2.02

g

u

₃

o

_{8;1 so the actual consumption was 2.7 lb NazC03/lb U308}

recovered. It was found that the stripped organi.c could be held

below 0.5 g U3o₈;1 only i f the carbonate strip flow was maintained

at 2.7 lb Na2co3/lb u_{3o8 or greater. A typical stripping gradient}

taken at 2.8 lb Na2co3/lb U3o8 is shown in Table IX. Average flowrates and .assays for the day the gradients were t.aken are

shown in Table IX and in the gradient tables which follow. At.

2.7 lb Na2C03/lb U3o8 or greater, the carbonate consumption was

considerably higher than .expected. Sulfate analyses of the

pregnant organic and the pregnant carbonate solutions showed a

l

~. neglibible entrainment of sulfuric acid, nor did the bicarbonate

/ content of the pregnant carbonate account for the added carbonate

(

consumption. Assays showed, however, that the average .EHPA .content

of the solvent was 0.36 M. Ass.ays of individual solvent additions

had all been very close ~o 0.30 M EHPA. Apparently there was a

preferential loss .of the kerosen;, presumably due to evaporation. The high EHPA content accounted for the unexpected carbonate con-sumption.

A stripping gradient taken on August 7 revealed a peculiar con-dition in the mixer-settlers which was called "inversion." A

gradient illustrating this condition is shown in Table X. The

uranium concentration in the carbonate solution had built up in the second and third stages until it was higher than in the preg-nant carbonate. Also the uranium concentration in the organic phase was higher than in the pregnant organic being fed to the circuit. Apparently this inversion was due to an insufficient quantity of carbonate being fed to the circuit.

Since the data showed that essentially all of the stripping was

accomplished in two stages, it was decided to eliminate one ·suage

from th~ circuit. Stripping was accomplished with the same

efficiency as with four stages, but as shown in Table XI, inversion

was still taking place. These data showed, however, that stripping

could be done in two stages; therefore, another stage was by-passed and the circuit operated with only two stages of stripping. A

gradie~nt was taken and the da.ta are presented in Table XII. Although

the operation was quite satisfactory, the data in Table XIII, show that the amount of Na2co3 cons.umed in excess of the theoretical requirement increased when using two stages.

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Table VIII

Eluex Circuit - Acid RIP Pilot Plant

CarJ;ona.te Stripping Data .~ 2..43 .lb IirazC03/lb.'U30S

Monticello Blend June 19 - July 9, 1956

Noo of stages

Pr.egnant organic, g U308/l

S.tripped organic, g _U308/l

~lowrate, ml/min

'

Carbonate strip solution, g u_308/l

feed rate, ml/min

g _Na2

co

_3/l lb Na2

co

3 /lb

u

3

o

8 4 13.98 0.032 821 nil 286 97 o5 2.43

Pregnant carbonate. solution, g U308/1 45.8

flowrate, ml/min 225

Extraction, %. 99o77

WIN- 70 29

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Organic g U30s/l .11.8 .6 .1 0.80 0.63 0.23 Table IX

Eluex Circuit - Acid RIP Pi]ot Plant

Monticello Blend July 16, 1956 Stage No. 1 2 3 .4 Carbonate Strip g UJOa/1 49.2 20.3 2.4 0.19 nil July 16 Average Pregnant organic Carbonate solution Stripped organic Pregnant carbonate 12.1 0.058 45.69 104 ;

-697 234 735 174

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Table X

Eluex Circuit - Acid RIP Pilot Plant

Stripping Gradient at 2,6 lb Na2

co

3 /lb

u

3

o

8

Monticello Blend August 7, 1956

WIN- 70 31

-Organic Stage Carbonate Strip

g

u

_3o8/l 12.4 27.7 27.3 4.4 0.43 Pregnant organic Carbonate solution S.tripped organic Pregnant organic No. 1 2 3 4 12.70 0.53 57.22 g

u

_3oa/l 59.8 106.7 107.7 14.9 nil August 7 Average 106 706 216 785 151

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Organic g U~Og/1 17.5 20.0 2.04 0.18 Table XI

Eluex Circuit - Acid' RIP Pilot Plant Stripping Gradient with Three Stages

Monticello Blend August 20, 1956 Stage No. 1 2 3 Carbonate Strip g U30g/l 68.8 7L6 8.49 nil August 20 Average Pregnant organic Carbonate solution Stripped organic Pregnant carbonate 18.23 0.36 64.96 103 907 319 989 237

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'):'able XII

WIN~70

~ 33 ~

Eluex Circuit ~ Acid RIP Pilot Plant

Organic

g U30g/l

17.2

7.09 0.57

Stripping Gradient with Two Stages Monticello Blend August 31, 1956 Stage No. 1 2 Carbonate Strip g

u

₃

o

₆₁₁ 61.2 20.2 nil August 31 Average Pregnant organic Carbonate solution Stripped organic Pregnant carbonate 17.21 0.35 59.68 104 899 319 973 258

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Table XIII

Eluex Circuit - Acid RIP Pilot Plant Stripping Data

Monticello Blend July 10 - August 30

No. of stages 4

Pregnant organic, g

u

_3o811 13.51

flow, ml/min 700

Carbonate solution, g Na2C03/l 103.9

flow, ml/min 208

Pregnant carbonate, g

u

_3o811 51.04

flow, ml/min 149

Stripped organic, g

u

_3o811 2.02

flow, ml /min 736

M

EHPA 0.360

lb Na2C03/lb u_{3o8 in pregnant carbonate}

1 2.84

Theoretical requirement, lb Na2co3/lb U308-/ 2.26

% _{Na2co3 in excess of theoretical requirement 25.7}

_3 _ _ 2_ 17.66 17.63 898 901 101.1 103.9 312 328 64.31 57.39 228 253 .0.38 0.64 971 980 0.339 0.320 2.15 2.35 1.77 1.71 21.5 37.4

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Solvent Loss

The solvent loss while using the pulse column for extraction and

the mixer-settlers for stripping was 0.0525 gal solvent/lb

u

₃

oa

produced or 3.43 gallons of solvent per 1000 gallons of raffinate. Solvent loss while both extracting and stripping in mixer.osettlers averaged 0.0589 gal/lb U308 produced or 3.34 gallons of solvent per 1000 gallons of raffinate. The solvent loss for the entire

test period averaged 0.054 gal/lb

u

₃

o

_{8 produced.}

G. Pre.cipitation

A total of 23 precipitations was made .during the test run. Sixteen

precipitations were made by ~cidifiying the pregnant carbonate

solution from the Eluex circuit to a pH of 3.0 and neutralizing

this solution with MgO. Reagent consumptions were· 1.44 lb H2S04 and

0. 217 lb MgO per lb U30₁₁, The average assay of the yellow cake

produced was 84.99% U308.

Six of the twenty-three precipitations were made by neutralizing the pregnant RIP eluate with NH3 and one was made by neutralizing

with NaOH. All seven of these precipitations were for the purpose

of alleviating a solution build·~!J.p ,ahead-of the Eluex circuit.

The yellow cake produced was filtered in a plate and frame press and both the filtrate and water washes were discarded to tails. Precipitation data are listed in Table .XIV ..and chemical analysis

of the yellow cake produced is shown in 'Table

XY!..

All' analyses'

except that of

co'j

meet specifications which are .now .. generally.

being used by the AEC for the present uranium .conc.entrate .pur-chasing contracts.

H. Tailings. Neutralization

Tailings neutralization tests on Monticello Blend ore were started

July 13, 1956. Ion exchange tails were fed by gravity to a 5x8-ft

thickener where Separan 2610 was added to flocculate the pulp. The thickener underflow was pumped to a sand sump where it was mixed with the sands from the No. 4 drag classifier and pumped to tailings. The thickener overflow was split so that part was recirculated to dilute the .Separan 2610 solution.and the remainder was either returned to the mill circuit via the steady head tank or discarded to tails.

Table XIV

Precipitation Data - Acid RIP Pilot Plant Monticello Blend

Precip Reagents Preg Filtrate Press Wash Yellow Cake

.Date Precip _H2so4 Eluate lb lb % lb

i956 No. Gal Agent lb

_{- -}

lb _{g u3o6/1 g U10g/l U30S · Gal . g u3os/l}

_!!.3Qs..

_.!.£..

_!!3Qa

_u3oe

6-21 1 1000 NJi4

-

-·- 7.76 0.025 0.21

-

_-

_-

88 65.84 57.94 6-24 2 325 NaOH 121.0

-·

46.54 0.36 0.98

-

-

-

163 73.74 120.20 6-28 3 342 MgQ 24.0 215 52.26 0.92 2.74 100 0.74 0.62 176 78.10 134.76 7-1 4 250 MgO 19.0 162 48.06 2.70 5.63 100 1.85 1.55 110 80.81 88.89 7-5 5 256 MgO 23.5 155 40.92 0.09 0.18 100 0.58 0.49 92 83.63 76.49 7-6 6 1000 NJi4

-

-

7.54 0.002 0.02

-

-

"

-

82 74.73 61.28 7-7 7 1000 NH4

-

-

-

0.003 0.03

-

-

-

105 64.92 61.68 7-8 8 250 MgO 22.75 152 51.39 0.01 0.02 100 0.008 0.01 120 81.58 97.90 7-10 9 1000 NH4

-

-

8.20 0.003 0.03

-

-

-

95 65.45 62.18 7-11 10 1000 NH4

-

-

7.19 nil

-

-

-

-

86 65.37 56.22 7-12 11 299 MgO 21.5 158 45.23 0.001

_-

100 nil

-

117 85.36 99.87 7-17 12 274 MgO 20.0 140 51.52 0.51 1.30 100 0.23 0.18 112 85.48 .95.74 7-22 13 266 MgO 19.75 126 62,93 0.002 0.004 100 0.001

-

105 85.58 89.86 7-24 14 1000 NH4

-

-

5.75 nil

-

-

-

-

70 58.90 41.23 7-28 15 300 MgO 24.50 147 57.02 0.001 0.003

-

-

156 83.48 130.23 8-3 16 250 MgO 26.0 138 53.92 0.009 0.019 100 0.005 0.004 121 88.56 107.16 8-8 17 257 MgO 22.0 153 57.37 0.001 0.002 100 0.007 0.006 134 87.20 116.85 8-14 18 257 MgO 23.0 147 55.02 0.005 0.011 100 0.015 0.012 143 88.51 126.57 8-17 19 257 MgO 28.5 154 62.43 0.001 0.002 100 0.001 0.001 138 86.31 119.11 ' ·:o:: H 8-21 20 257 MgO 27.0 196 67.67 0.014 0.030 100 0.034 0.028 152 89.51 136.06

wz

0'> I 8-24 21 250 MgO 22.5 185 59.32 0.014 0.029 100 0.008 0.007 i38 88.38 121.96 1--l 8-28 22 257 MgO 25.0 160 62.85 0.002 0.004 100 0.002 0.002 144 84.79 122.10 0 9-1 23 190 MgO 31.5 141 53.73 0.040 0.063 100 0.025 0.021 109 82.54 89.97

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Table X'J

Yellow Cake Analysis - Acid RIP Pilot Plant Monticello Blend

Analysis Per Cent

U308 81.96 v2o5 0.006 P04 0.35 Mo 0.38 B 0.0007 Halogens

,.co

.02 F O.Oll Fe 0.50 Cu 0.0042 As 0.012 Ca <O.l

so

₄ 4.23

co

₃ 1.03

!/

Insoluble 0.64 H20 1.12

l l

Does not meet current AEC specifications

WIN- 70 37

-(

In the neutralization circuit' the addition of 97 lb hydrated lime/ton of· original feed resulted in a neutralized slime having a pH of 6,6, while the addition of 85 lb hydratedlime/ton of ore feed resulted in a pH of 6.2. A' Separan 2610 addition of 0,126 lb/ton ore -,was required to settle the pulp effectively when using 97 lb lime/ton of ore and 0.136 lb was required when using 85 lb lime/ton. Table XVI lists the pertinent data obtained from the neutralization tests. Appendix Table 10 lists the daily neutralization data.

The thickener circuit was analyzed for dissolved solids and .sulfate ion. The results of these analyses are presented in Table XVII. A quantitative spectrographic analysis of the thickener overflow water is presented in Table XVIII.

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Table XVII

Tailings Neutralization - Acid RIP Pilot Plant .Dissolved Solids. and ·Sulfate Analyses

Monticello Blend

Thickener Overflow

Date Dissolved Solids

Sd4

,

% ,S04 in

WIN-70 39 -1956 ppm Pm!L Dissolved Solid.s 7-25 7-27 8-2 8-9 7-25 7-27 8-2 8-9 8~25 7-27 8-2 8-9 6874 7139 7826 5996 7350 6685 7389 7861 4050 4288 3900 4750 2 88 4567 4413 5237 4017 Thickener Underflm< 4526 4448 4978 5251 Final TaiL 2564 2644 2575 2000 D:!still ed Hater 2 Tap Water .. 11 66.44 61.82 66.92 66.99 61.58 66.54 67.37 66.80 63.31 61.66 66.03 42.11 100.00 12.50

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Table XVIII

Tailings Neutrali~ation - Acid RIP Pilot Plant

Quantitative Spectrographic Analyses - Thickener Overflow Monticello Blend

Date Anal sis

1956 Ca

_M&

Cu Fe Li Mn Na Si Sr 7-25 Mm Mm mt .m t Mm M Mm mt 7-27 Mm Mm t m M mt 8-2 Mm Mm m Mm. mt 8-9 Mm Mm m Mm mt Code: MM,

>

10 g/1 m, 0.01 to 0.1 g/1 M, 1 .to 10 g/1 mt, 0.001 to 0.01 g/1 Mm, 0.1 to 1.0 g/1 t, <0.001 g/1 not detected Metallurgical Balanc.e

A metallurgical balance for the entire run is shown in Table XIX. Over-all calculated recovery based on the uranium in the mill feed and known losses was 92.41 per cent. The uranium in the yellow cake produced amounted to 91.85 per cent of that in the mill feed result-ing in an unaccountable loss of 0. 56 per cent. Average leach extrac-tion was 96.3 per cent and ion exchange recovery averaged 98.9 per cent.

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Table XX

Metallurgical Balance - Acid RIP Pilot Plant Monticello Blend

Tons _U308

Treated % g/1

Feed 405.67 0.317

Residue 405.67 0.012

Soluble loss in drag sands 0.007

Leach liquor 0.783

Adsorption tails 0.007

Pregnant eluate on hand at end of run

Feed to solvent extraction 6.40

Raffinate pumped to tails 0.15

Press filtrate 0.21

Water wash 0.23

Calculated recovery

Yellow cake produced 2882 lb 8L96

Unaccountable loss WIN- 70 41 -U308 % of Content lb Total 2571.51 100.00 95.15 3,70 0.83 0.03 2475.53 96.27 22.78 0.89 45.44 1.77 2407.31 93.61 16.68 0.65 11.31 0.44 2.93 0.11 2376.39 92.41 2361-.92 91.85.!/ 14,47 0.56

Overall recovery 96.32 per cent when including uranium in inventory as pregnant eluate

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APPENDIX

~

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.~ /

' ' _'

Table 1

Daill:: Grindins· and Leach ins Data··..,, Acid RIP Pilot Plant

,..-Monticello Blend

Grinflins Circuit Leachin~ Circuit

Leach

Feed BMCO Fres Recycle

Date. Tune lb/hr Ton/;aay 0308 _{Terminal Terminal HzS04 H7S04 Residue Ext'n}

1956 Hr Wet Dry Density .. %. _{' pH} emf, -mv lb/ton lb ton % _{U308 .} %

U.J.0

₈

6-15 15.83 1038 7.97 1.45

-

1.0

-

187 6-16 1.00 1036 0.50 1.46

-

~.o 380 92 6~17 24.00 891 10.37 1.45 0.272 1.1 380 111 52.10 0.011 -95.96 6-18 24.00 563 6.55 1.45 0.263 _1.2 370 155 82.49 0.013 95.06 6-19 24.00 522 6.08 1.45 0.248. 1.1 379 138 89.89 o·.o11 95.56 6-20 24.00 522 6.11 1.45 0.243 1.2 376 119 87.23 0.014 94.24 6-21 24.00 520 6.02 1.45 0.236 1.2 373 120 90.79 0.010 95.80 6-22 24.00 521 6.06 1.45 0.238 1.2. 374 113 94.82 0.012 94.96 6-23 24.00 521 6.09 1.45 0.259 1.2 374 104 90.60 0.012 95.37 6-24 24.00 521 6.06 1.45 0.345 1,3 373 116 94.83 0.012 96.52 6-25 24.00 521 5.97 1.44 0.364 1.2 371 110 94.34 0.014 97.22 6-26 24.00 522 6.07 1.45 0.367 1.3 371 120 101.31 0.014 95.41 6-27 24.00 522 6.07 1.45 o. 370. 1.2 373 112 91.08 0.012 96.22 6-28 24.00 522 6.12 1.44 0.476 1'.3 376 164 85;78 0.013 97.27 6-29 24.00 523 6.16 1.44 0.463 1:2 391 136 81.17 0.012 97.41 6-30 24,00 523 6.20 1.45 0.424 1.2 392 195 7:10 0.012 97.17 7~1 24.00 522 6.20 1.45 0.364 1,~ 390 202 10.32 0.013 96.43 7-2 24.00 521 6.06 1.45 0.313 1.2 393 130 80.36 0.012 96.17 7-3 24.00 521 6.06 1.45 0.415 1.2 _{' .} 392 137 71.78 0.012 97.11 7-4 24.00 520 6.04 1.45 0.433 1.3 388 204 13.41 0.014 96.77 7-5 24.00 521 6.03 1.45 0.430 1.2 389 186 24.88 0.014 96.74 7-6 24.00 524 6.07 1.46 0.448 1.2 390 189 39.21 0.012 97.32

•:e:

_H 7-7 24.00 524' 6.05 1.46 0.450 1.2 389 219

1

0.012 97.33 -1'-21 N l 7-8 24.00 520 5,99 1.45 0.463 1.2 389 243 0.011 97.62

·~

7-9 24.00 524 6.10 1.4:; 0.448 1.1 391 232 0.013 97.10 7-10 24.00 522 6.10 1.45 0.436 1.1 388 211 0.011 97.48 7-11 24.00 520 6.00 1.45 0.405 1.1 390 245 0.008 98.02

Table 1 (Contd.)

Daily Grinding and Leaching Data.- Acid RIP Pilot Plant Monticello Blend

Grindin~ Circuit Leachin~ Circuit

Feed BMCO Fresh Recycle Leach

Date Time lb/hr Ton/day _{U308 Terminal Terminal H2}

_so

_{4 H2S04} Residue Ext'n

1956

_....!!E...

Wet Dry Density __!_ pH

' emf, -mv lb/ton lb/t<>.I1 % u~o,. % u~o,.

7-12 24.00 363 4.28 1.45 0.392 1.0 382 221

I

O.Oll '.!7.19 7-13 24.00 349 4.12 1.44 0.394 1.2 390 304 0.008

y

+

7-14 24.00 351 4.12 1.45 0.383 1.1 397 359

""

0.007 "" 7-15 24.00 351 4.08 1.45 0.354 1.1 400 351 ... 0 0.007

,_

.

7-16 24.00 349 4.11 1.62 0.392 1.0 408 325

,..

Q) 0.006

"'

"'

7-17 24.00 348 4.05 1.63 0.345 1.0 408 303

_""

0.006 >. 7-18 24.00 349 4.10 1.63 0.338 1.1 405 248 ...

"'

0.007 Q)

,..

7-19 24.00 351 4.12 1.63 0.338 1.2 411 337

""

....

0.007 Ei 7-20 24.00 847 4.08 1.63 0.316 1.2 385 363 00 0.009

e

<J 7-21 24.00 335 3.94 1.63 0.286 0.7 389 196 ...

"'

7-22 24.00 350 4.12 1.45 0.286 1.0 385 245

,..

0.009

""

"

Q) 7-23 24.00 350 4.16 1.45 0.281 1.1 391 216

""

0.008

....

_"'

7-24 24.00 350 4.11 1.45 0.260 1.1 391 231

....

"'

0.006

....

"

7-25 24.00 ~350 _{4.11 1.45 0.264 1.2 390 238} ... _0.006

_"

"'

....

7-26 24.00 350 4.11 1.45 0.283 1.2 382 241

....

0.005 u

"'

7-27 24.00 351 4.14 1.45 0.281 1.1 393 216

....

0 0.006 7-28 24.00 350 3.06 1.45 0.273 1;1 400 224

_""

0.005 7-29 24.00 351 4.08 1.45 0.282 1.,1 400 235

_If

Q) 0.005 7-30 24.00 352 4.09 1.45 0.283

-

-

-"

0.005 •:C 24.00 4.06 1.45 0.284 Ll 400 213

""

0.003 ""!;;! 7-31 351 24.00 350 4.01 1.45 0.278 1.1 390 231 Q) 0.002

...,,

8-1

....

-.J

"'

•o 8-2 24.00 350 4.05 1.46 0.270 1.1 390 245

"'

0.004 ... 8-3 24.00 350 4.04 1.45 0.265 1.1 394 241

_""'

0.004

""'

8-4 24.00 352 4.12 1.45 0.262 1.0 374 242 _~ 0.005 8-5 24.00 351 4.05 1.45 0.250 1.0 390 230 0.004

r"-

n

.~

Table 1 (Contd.)_

-Daily Grinding· and Leaching Data- Acid RIP Pilot Plant Monticello Blend

Grindin~ Circuit Leachin~ Circuit

Feed BMCO Fresh Recycle Leach

Date Time lb/hr Ton/day U308 Terminal Terminal H2

so

_{4 H2}

so

_{4 Residue} Ext'n

.!.22.§.- Hr Wet DrJ!: Densitl!: __.!._ EH emf, -mv _{lb/ton 16/ton % u3oa} %

u

₃

o

₈

8-6 24.00 350 4.11 1.45 0.263 1.0 380 226

43~63

0.004.!/

t

8-7 24,00 466 5.35 1.45 0.247 1.1 400 189 0.005 8-8 24.00 534 6.28 1.44 0.248 1.1 396 155 44.96 8-9 24.00 535 6.25 1.45 6.260 1.2 398 186 43.01 0.006 8-10 24.00 535 6.31 L45 0.278 1.2 405 203 46.08 0.005

.,

.

" » 8-11 24.00 535 6.24 1.45 0,260 1.1 409 211 46,88 0.005 ~$-l~

"'

"

"'

8-12 24.00 536 6.27 1.45 0.273 1.1 404 223 38.39 0.005 ... :> • ::l 0 " ' 8-13 24.00 535 6.23 1.45 0.279 1. 2 .. 403 223 43.15 0.005 0 0 " '

...

"

8-14 24.00 535 6.24 1.45 0.282 1.2 410 164 64.96 0.007

"'

... 8-15 24,00 535 6.28 1.45 0.283 1.1 408 138 66.70 0.006 u

t

8-16 24.00 535 6.26 1.45 0.276 1.2 393 122 64.89 0.011 96.01 8-17 24.00 541 6.25 1.45 0.264 1;2. 388 131 64.17 0.015 94.31 8-18 24.00 537 6.24 1.45 0,268 1.2 403 104 64.77 0.013 95.15 8-19 24.00 536 6.22 1.45 0.275 1;3 400 145 62.96 0.014 94.91 -8-20 24.00 536 6.27 1.45 0.273 1.2 400 104 58.48 0.015 94.51 8-21 24.00 533 6.20 1.45 0.277 1.3 398 153 75.93 0.014 94.95 8-22 24.00 536 6.22 1.45 0.273 1.2 410 72 79.38 0.015 94.51 8-23 24.00 536 6.20 1.45 0.263

-

-

-

80.14 0.021 92.01 8-24 24.00 534 6.21 1.45 0 .• 285 1.2 422 120 75.82 0.016 94.39 •:0: ~!2! 8-25 24.00 536 6.22 1.45 0.296 1.3 416 143 78.71 0.009 96.96 ~ ·1 8-26 24.00 535 6.26

-

0,296 1.2 411 139 80.70 • 0.010 96.28 I --J 8-27 24.00 538 6.33 1.45 0.291 1.2 415 119 79.16 0.010 96.56 0 8-28 18.50 535 4.82 1.45 0.323 1.2 411 109 81.04 0.014·. 95.67

c

c

(

Screen Analysis

Table 2

- Ball Mill Feed - Acid RIP Pilot Plant

Monticello Blend

% Retained U30a Distribution

Screen Weight Cumulative Assay Weight Cumulative

Size % % % U30s % % +0.525 in. 0.55 0.199 0.35 0.371 in. 5.12 5.67 0.124 2,00 2.35 3M 6.31 11.98 0.306 6.08 8.43 4 6.13 18.11 0.454 8.69 17.12 6 6.59 24.70 0.296 6.08 23.20 8 5.21 29.91 0.446 7.25 30.45 10 5.21 35.12 0.455 7.54 37.99 14 5.12 40.24 0,396 6.38 44.37 20 5. 86 46.10 0.371 6.95 51.32 28 7.41 53.51 0.326 7.53 58.85 35 11.16 64.67 0.216 7.53 66.38 48 10.98 75.65 0.236 8.11 ' 24.49 65 4.94 80.59 0,262 4.06 78.55 100 7.23 87.82 0.280 6.37 84.92 150 4.31 92.13 0,290 4.06 88.98 200 2.75 94.88 0,368 3.19 92.17 270 1.09 95.97 0.426 1.45 93.62 325 1. 74 97.71 0.455 2.61 96.23

-

325 2.29 2.29 0.529 3. 77 3. 77

c

·Table 3

Screen Analysis - Ball Mill Classifier Overflow Monticello Blend

Screen % Retained

Size Weight Cumulative Assay

Mesh % '7. '7. U30a

+

20 0.08 0.225 28

o.

89 0.97 0.276 35 2.27 3.24 0.271 48 5.14 8.38 0.278 65 9.56 17.94 0.283 100 9.19 27.13 0.269 150 7.90 35.03 .0.271 200 5.64 40.67 0.231 270 3.50 44.17 0.269 325 5.84 50.01. 0.322

c

-325 49.99 49.99 0.379

c-·

WIN- 70 46

-- Acid RIP Pilot Plant

U308 Distribution Weight Cumulative '7. % 0.05 0.75 0.80 1.88 2.68 4.37 7.05 8.28 15.33 7.57 22.90 6.54 29.44 3.98 33.42 2.88 36.30 5.75 42.05 57.95 57.95

Table 4

Screen Analyses - Cyclone Circuit - Acid RIP Pilot Plant Monticellu Blend

No. 1 Drag No. 1 Cyclone No. 1 Cyclone No. 2 Drag No. 2 Cyclune

Screen Overflow Overflow Underflow Overflow Overflow

Size Wt Cum Wt Cum Wt Cum Wt Cum Wt Cum

Mesh % % % % % % % % % %

+

35 48 0.12 0.12 65 0.23 0.35

o.

82 0.24 0.36 100 1.12 1.47 1.48 2.30 0.36 0.72 1.38 150 2. 82 4.29 4.35 6.65 0.48 1.20 4.13 5.51 200 3. 72 8.01 6.24 12.89 1.08 2.28 5.05 10.56 270 2.59 10.60 4. 35 17.24 1.08 3.36 3.67 14.23 325 3. 82 14.42 6.57 23.81 2.78 6.14 5.73 19.96 -325 85.58 85.58 100.00 100.00 76.19 '76 .19 93.86 93.86 80.04 80.04 No. 2 Cyclone Underflow Wt Cum % _~ 0.06 0.06 0.12 0.17 0.29 0.33 0.62 0.69 1.31 1.66 2.97 1.93 4.90 4.05 8.95 91.05 91.05 •:<:: H -1>-21

...

·<:3

/--:----\

n

Table 5

Screen Analyses- Drag, Sands- Acid RIP Pilot Plant Monticello B4end

No. 5 L. T.

Screen Discharge No. 1 Drag No. 2 Drag No. 3 Dras;

'

Size Wt Cum Wt Cum Wt Cum Wt Cum

Mesh _{_J_} % % % % % % _~

+

20 0.24 0. 32 0.16 28 1.19 2.69 2.93 1.82 2.14 1.32 1.48 35 2. 85 4.04 8.55 ll.48 5.24 7.38 4,20 5.68 48 4.93 8.97 16.98 28.46 10.91 18.29 9.05 14.73 65. 7.37 16.34 23.42 51.88 17.43 35.72 13.58 28.31 100 6.33 22.67 16.64 68.52 13.48 49.20 10.95 39.26 150 6.27 28.94 11.49 80.01 11.66 60.86 9.55 48.81 200 4.31 33.25 7.75 87.76 8.02 68.88 8.47 57.28 270 2.43 35.68 2.95 90.71 3.74 72.62 4.86 62.14 325 2.64 38.32 2.49 93.20 3.53 76.15 13.74 75.88 -325 61.68 61.68 6.80 6.80 23.85 23.85 24.12 24.12 No. 4 Drag Wt Cum % % 0.70 2. 82 3.52 5.63 9.15 9.58 18.73 8.45 27.18 7.89 35.07 4.65 39.72 2. 82 42.54 3.52 46.06 53.94 53.94 ·') •:0:

-1'-!2!

(X>~ 1 0