Solubility Ammoniacal Ammonium Salt Solutions of Copper, · Solubility in Ammoniacal Ammonium Salt Solutions of Copper, Nickel, ... The able assistance Dr. I. Graydon for ninning

Solubility in Ammoniacal Ammonium Salt Solutions of

Copper, Nickel, and Cobalt Components of a Waste Product

hoduced at Incois Port Colbome Cobalt Refinery

Selwyn R. FiRh

A thesis submitted in conformity with the requirements for the degree of Master of Applied Science,

Department of Chernical Engineering and Applied Chemistry University of Toronto

O Selwyn R. Firth, 200 1

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ACKNOWLEDGEMENTS

The author thanks Professor Frank R. Foulkes, his supervisor, for his invaiuable assistance

encouragement and skihl guidance.

The heipfùl discussions with Professors D. Krk, and V. Papangelakis are gratefully

appreciated..

The able assistance Dr. I. Graydon for ninning thermogravimetric analysis as well as for

discussions of the experimental iesults of the work is especially appreciated.

The assistance of Ying Lee and Dan Mathers of the Analyst Lab in the Chemistry

Department for assistance with the FAA and ICP analyses is acknowledged, as is the

kindness of Phil Bearse and Dan Young of Inco's Port Colbome Facility for providing

assistance and samples of the waste stream.

The helpful discussions and encouragement fiom fellow graduate students in room 334

and room 233 are greatly appreciated.

Selwyn Robert Firth Master of Applied Science in Chemical Engineering Depanment of Chemical Engineering, U of Toronto 200 College St. Toronto, Ont. M5S 3 E5

ABSTRACT

The feasibility of using different ammoniacal salt solutions, for the dissolution of the nickel. copper, and cobalt components of an industnal waste from the INCO Pon Colborne. Ontario cobalt refinery was investigated.

The solubiIization of the cornponents was examined for various reagents on an aged sample provided, which represents the 25 year accumulation of the waste at the facility.

Several types of the waste were processed differently and then were compared to see if processing conditions affected the solubility of the different components.

It was not possible to solublize al1 of the metals from the waste however. it was shown that the processing conditions and age of the material make a difference in the solubilities of the different cornponents. The maximum solubilities of the unfiltered material were; copper. nickel and cobalt, 98, 88, 76 percent respectively.

It was demonstrated that the three metals could be electrolyticly removed from the ieachate.

TABLE OF CONTENTS

Acknowledgcments

Abstract

Tablc of Contents

List of Tables

List of Figures

i Introduction

2 Thcory and Litenturc Rcvicv

3 Esperimental

3. 1 Appamtus

3. 2 Anal!-tical Equiprncnt

3. 3 Rcagcnts

3. 4 Proccdurc

3. 5 Instmmcnt Calibration

5. 6 Analysis

4 Results and Discussion

4.1 Effcct of Leachant on rnctal solubiliiy

4. 1. a Ammonium Hydrosidc

4 I b Ammonium Sulphote

4 1 c Ammonium Cliloridc

4. 1. d Ammonium Citrate

4. 1. c Ammonium Acctatc

4. 1. f. i Ammonium Sulphate with added Ammonium Hydrosidc

4. 1. f. ii Ammonium Hydrosidc with Addcd Ammonium Sulphatc

4. 1. g. i Ammonium Chloride with added Ammonium Hydrosidc

4. 1. g. ii Ammonium Hvdroside with addcd Ammonium Chloridc

4. 1. h. i .4mmonium Citrate with addcd Ammonium Hydrosidc

4. i . i. Summary of DifTercnt Leachants

4.2 Effect of Lçaching Time

4.3 Secondan- Leaching

4.4 Effect of Hcating

4.5 Effat of Ageing

4.6 Thennogra~imetric Analyses

4.7 Plant Proccssing Conditions

4.8 Elecuo-reduction

-5.8. 1 Electro Stripping

4.8. 2 Current Eficiency

5 Conclusions

6 Recommendations

7 Rcfercnces

8 Nomenclature Used :u'PESDL\: :l

.-VPESDR B

APPEYC'DlS C

..VPENDIS D

LIST OF TABLES

Table 1 Summary of different leachants

Table 2 Cornparison of first and second leaches

Table 3 Cornparison of different treatments

Table 4 Electro- reduction of rnetals in solution

LIST OF FIGURES

Fig. 1 Extractions using Ammonium Hydroxide

Fig. 2 Extractions using Ammonium Sulphate

Fig. 3 Extractions usiny Ammonium Chloride

Fig. 4a Extractions using Ammonium Citrate

Fig. 4b Extractions using Ammonium Citrate

Fig 5 Extractions using Ammonium Acetate

Fig 6 Extractions usinç Ammonium Sulphate with Ammonium Hydroxide

Fig. 7 Extractions using Ammonium Hydroxide with Ammonium Sulphate

Fiç. 8 Extractions using Ammonium Chloride with Ammonium Hydroxide

Fig. 9 Extractions using Ammonium Hydroxide with Ammonium Chloride

Fig. I O Extractions using Ammonium Citrate with Ammonium Hydroxide

Fig. 1 1 a 24 h Copper Extractions

Fig. I I b 24 h Nickel Extractions

Fig. 1 1 c 74 h Cobalt Extractions

Fig. 1 2 Extractions with Heat

Fig. 13 Thennogram I untreated MC0 material

Fig. 14 Thennogram 2 extracted INCO material

1 INTRODUCTION

The work descnbed herein is an investigation of a potential waste reduction and resource

recovery process for an industrial waste produced by MC0 at its Pon Colbome, Ontario, cobalt

refinery .

The advent of concems over environmentai pollution in the 1970s ' ' ' led to mandatory

reductions in waste strearns. The statutes require that waste waters contain less than 5 ppm of

designated heavy metals such as copper, nickel, and cobalt.' ' ' The heavy metal hydroxide

precipitates fiom the electroplating and the mining industries were thus created as companies

complied with the regulations.

Treatment processes to lower the concentrations of designated heavy met& to levels of

less than 5 ppm must do so without dilution of the waste stream.' ' ) The insolubility of most

transition metal hydroxides at pH's of 8 - 10 "' provides a simple and cost effective method of

complying with govemment requirements for waste water discharge. The result of treating waste

water with calcium oxide ( lime ) or sodium hydroxide ( caustic soda ), produces a heavy metal

precipitate which settles out of the waste stream; this precipitate then can be collected and

dewatered to forrn a filter cake.

The preferred method of treating the large volumes of waste water at MCO's Pon

Colborne facility uses lime to adjua pH levels of the waste stream. Calcium carbonate is formed,

because of the high carbonate levels in the waste stream, which are the result of using fiesh water

from limestone formations in southem Ontario, and precipitates and mixes with the insoluble

metal hydroxides.

Ca0 + 40 --> Ca ( OH )2

Ca ( OH )2 ---- > Ca( OH )' + OR pH - 12

Ca ( OH ), + HCO', -----> CaCO, ( s ) + -0 +OH-

Me2' + 2 OH- ------ > Me(OH):(s)

The use of calcium oxide rendes the waste product unsuitable for acid leaching due to the

reactivity of the calcium carbonate formed with acids.

CaCO,(s) + 2K -----> Ca" +no +CO:(g)

Similar heavy metal hydroxide precipitated wastes are also produced by the electroplating

industry. The metal content of the different filtercakes can range From 1 to 5 percent depending

on the operator and the treatment method and precipitant chosen.

MC0 produces approximately 500 tonnes per month at 50 wt % water . of this product

in its Pon Colborne refinery. The waste sample, provided by M C 0 for this project, contains

approximately 0.6 % cobalt, 1.4% nickel and 1.7 % copper on a dry weight basis. Femc

hydroxide is 5 %, alurnina 1 S%, siiica 1% and approxirnately 85 % calcium carbonate. The pH of

the s l u q was 9.54. The actual material varies on a daily basis, depending on the upstream

processing conditions; however a given 20 kg grab sample is very uniform.

In 1994 the electroplating companies in south-western Ontario were producing another

combined 150 tonnes a month of wet filter cake containing 3- 5 % nickel on a dry basis or again

approximately haif that value wet.' ' ) These wastes may also contain quantities of chromiurn

hydroxide which cm render the wastes unsuitable for conventional smelting but which can be

processed by t his method.

INCO has been accumulating its material for the past 25 years at the Pon Colbome

facility. An estimate of the value of the rnetals contained in the waste material is approximately

li I million annually for iNCO at the Pon Colbome operation. There is also approximately $ 5 -

10 million of waste generated by the nickel / chrome electroplating seaor annually as well as a

substantiai amount of copper waste from circuit board manufacturers.

It is important to recover and recycle as much of our resources as we cm and to lirnit the

impact of disposing of the by products of out civilization as much as possible. Some nickel wastes

can be recovered by smelting if they have Iimited chromiurn content. The process herein descnbed

places no such limitation on the wastes.

It is well known that copper, nickel, and cobalt form soluble ammonium cornplexes(') and

that Shemtt Inc..' ) employs an oxidizing ammonium pressure leach process to recover copper,

nickel, and cobalt from sulphide ores. The ammonium salt and ammonium hydroxide leaching

process described in this thesis attempts to evaluate the recoverability of copper, nickel and

cobalt from the oxidized hydroxides found in the INCO waste. The process operates at room

temperature or higher and atmosphenc pressure, making it less expensive fiom a capital

standpoint than a pressurized system, ideaily leaving a markedly less hazardous product that can

be disposed of with a reduced environmental impact. The use of an ammonium-based electrolytic

process to recover waste materials of copper, nickel. and cobait is not found in the literature,

although nickel ammonium sulphate electroplating bathsc6 ' are sometimes used. Vogel describes a

quantitative analyticai technique that electrowins nickel from an ammonium solution.' ' '

Shemtt International employs a hydrogen reduction systemï a ) to recover the cobalt and

nickel fractions from its process Stream, producing substantial quantities of ammonium sulphate

( sold as fertilizer ) as a by product. The process proposed here is a method to recycle the

ammonium sait / hydroxide solution, since there is no added sulphate from the feedstock, as is the

case with Sherritt.

The work described herein is an attempt to develop and evaiuate a method of using a

combination of ammonium saits and ammonium hydroxide at atmosphenc pressure to dissolve

the vaiuable CO-precipitates of copper, cobait and nickel into an aqueous solution, followed by an

electrowinning process for their separation and recovery from the pregnant solution, thereby

allowing the leachant solution to be regenerated to effect a closed loop recovery process for

copper, nickel, and cobalt.

This work is an attempt to examine factors which affect the solubilization and recovery of

valuable minerals fiom the iNCO waste product descnbed earlier.

2 THEORY AND LITERATURE REVIEW

Priestly first produced amrnonia gas '9'in 1754 by heating lime with sa1 ammoniac

( ammonium chloride ), which had been known since about 400 BC. The sal ammoniac was

narned for the town of Ammon in Egypt where it was first produced.

It is well known that nickel, copper. and cobalt form soluble complexes with arnmonia and

ammonium salts. ' ''

The stepwise formation constants for arnrnonia metal complexes were extensively

investigated in the 1 930s by J. Bjemm, who used a glass electrode.' ' ' Me2- + MI, -----------> M~W,"

Me( NH, )," + NH, ------> Me( NH, ):'

The use of ammonia leaching was pioneered by Caron' 'O ' in the early part of the twentieth

century. Caron used an ammonium hydroxide and ammonium carbonate mixture to leach nickel

From reduced ores. In the late 1940s and early 1950s Shemtt Gordon Mines ( now Shemtt

International ) discovered that the use of ammonia under oxidizing conditions ar elevated

temperatures and pressures would oxidize and dissolve the sulphidic nickel and copper ores

without prior reduction.'"'

Sherritt then developed the process further to remove copper and iron contaminants and

to separate and reduce the nickel and cobalt fractions using hydrogen gas under pressure.' ' ' The

depleted solution of ammonia and ammonium sulphate then was stripped of the volatile ammonia

gas, which was recycled, while the ammonium sulphate was crystallized and sold as fertilker.' "'

The use of ammonium sait and ammonium hydroxide solutions. on the other hand, do not react

with the calcium carbonate or the ferric hydroxide, alumina or silica fractions. ( See Appendix B )

Thus it seemed ideai to dissolve the valuable metal components using a combination of

those reagents. The electrolytic separation of copper fiom nickel and cobalt can be achieved in

acid electrowinning systems ' l 3 ' and the same may be possible with ammoniacal solutions. ~ogel"

has described a quantitative electrolytic procedure for the determination of nickel in ammonicai

solutions, so it may be possible to produce a cobalt nickel alloy by electrowinning if the copper

first can be separated.

If electrolytic separation of copper is not possible, another technique to separate the

copper might be the use of sulphur- bearing chemicais, as implemented by Shemtt.' " ' Sherritt aiso uses an oxidative procedure that preferentially oxidizes the cobaltous ions to

cobaltic, leaving the nickelous ions which then are selectively reduced in the presence of the

cobaitic ions to separate the nickel and cobalt Fractions' "' since cobalt has the ability to form

cobaitic amine complexes whereas nickel doesn't:'"

~CO(NH,);' + N~(NH,),' + 40 + 112 O2 W ! O H ., 2Co(NH3):+ + Ni(NH,)," + ZOH.

3 EXPERIMENTAL

3. 1 Amaratus

The majority of the experiments were performed using 250 mL erlenmeyer flasks equipped

with a magnetic stir bar and sealed with parafilm. Most of the expenments were conducted at

room temperature ( 2 1 - 23 deg C ) and atmosphenc pressure for two hours. Heated experiments

were conducted using a reflux condenser, seded. but not pressure tight.

3. 2 Analvtical Eauipment

Attempts were made to use standard analytic techniques such as those found in Vogel ' ' '

for the analysis of nickel. However. this procedure was suitable oniy for certain reagents and was

abandoned. The use of UV spearoscopy also was attempted but this too was abandoned as

impractical due to the difficulty of setting up standard solutions. since dl three metal ammonia

complexes absorb light in the sarne range. Thus. depending on the ratio of metal complexes in

soiution one could get readings that were the same but the two solutions could have different

levels of ail three metal complexes.' l 3 )

Atornic Absorption Spectroscopy was found to be effective but too time consurning for

the number of samples. Induaively Coupled Plasma spectroscopy ( ICP ) finally was chosen for

the majority of the analyses. The ICP analyses were contracted to the Analyst Lab located in the

Lash Miller Chemistry building at the university of Toronto.

Thermogravimetrk analyses were performed by Dr. J. Graydon, using a Dupont

Instmments Mode1 93 1 thermogravimetric analyser located in Prof Kirk's laboratory.

3.3 Reaeents

Al1 solutions were prepared from deionized distilled water of 18 Mohm- cm resistivity.

using a MILLIPORE - Q WATER SY STEM deionizer.

Al1 reagents were ACS grade, ammonium hydroxide, ammonium sulphate, ammonium

chlonde, ammonium acetate, citric acid. sulphunc acid, nitnc acid, hydrochloric acid, potassium

hydroxide. nickel sulphate, copper sulphate, and cobalt nitrate.

Analytical standards were AA grade for AA anaiysis at 1 O00 PPM ( BDH AA Standards ).

ICP standards were Specpure@ certified NBS traceable.

Al1 solutions and residue washings were made with the 18 Mohm- cm deionized water.

3.4 Procedure

1 Extractions

A slurry was made by blending approximately 1.5 kg of the MC0 filter cake with

deionized water to a volume of 2.5 L.

Dual samples then were taken for drying at 250 C and at 105 C to establish the solids

content (approximately 30 % by weight ) and to determine which temperature gave more accurate

values for the solids content. The 105 C drying was within 0.2 percent of the 250 C drying.

Leaching experiments were set up based on the metal content of the slurry, as eaablished by ICP

andysis of either HCI or HNO, digests of a weighed sample of the sluny.

lnitially a set volume of the slurry was measured out using a calibrated graduated

cylinder. The samples then were quantitatively transferred using 1 x 10 rnL wash foiiowed by 2 x

5 rnL washes of deionized water. Later, samples of the well k e d s l u q were weighed into the

250 mL erlenrneyer flasks, a measured quantity of an ammonium salt or concentrated ammonium

hydroxide reagent added, the flask sealed with parafilm and mixing comrnenced for five hours.

Samples were taken hourly and the solutions and residues were analysed for copper, nickel, and

cobalt. It was determined From these experiments that very h i e extra material dissolved between

2 and 5 h. Thereafter the reactions were run for 2 hours.

At the end of the experiment the samples were centnfbged and then were decanted to

separate the pregnant solution from the residue. The residues then were re-suspended in fresh

deionized water. The washed residues then were centnfuged a second time. Washing was

repeated four times with wash ratios of 2 volumes of fresh water to 1 volume of retained solution.

This ensured that after washing the retained liquid per washing contained no more than 33 % of

the amount of liquid retained pnor to the wash. The clear coloured supernatant washes were

added to the pregnant solutions of the respective samples.

The respective rnixed washings and pregnant solutions then were diluted to a standard

volume using volumetnc flasks ( normally 250 mL class A ). Sarnples were retained for later

analysis. The retained samples were fbnher diluted by a known amount with 5 percent v/v nitric

acid to be in an accurately measurable range for the instrument ( For ICP and AA this was at O -

10 ppm )-

Residues of ~amples were digested using concentrated nitrk acid, and mass balances were

performed to ensure that the extracted solution contained metals in proportion to the original

unreacted product analysis.

3. 5 Instrument Calibration

3.5. 1 Atomic Absorption Spectroscopy

Fresh unopened AA standards were used to calibrate the AA spectrometer. The original

solutions were 1000 pprn guaranteed 5 5 ppm.

Calibration standards of 1, 2 and 5 pprn were made. Dilute standards of 100 rnL at 100

pprn were made by taking a 10 mL aliquot of the 1000 pprn standard and diluting to 100 mL using

class A volumetnc glassware.

A funher dilution then was made by taking a 10 rnL aliquot of the 100 pprn standard and

diluting to 200 mL for a 5 pprn standard.

An 80 rnL aliquot of 5 pprn standard then was diluted to 200 mis for a 2 ppm standard.

and a 50 mL aliquot of the 2 pprn standard then was taken and diluted to 100 rnL for the 1 pprn

standard.

The correlation coefficients of the analyses were 0.9999 using these standards.

3. 5. 2 Inductively Coupled Plasma

A 10 rnL aliquot of a rnixed 25 element, Nationai Bureau of Standards, traceable standard

was used to make 100 rnL of a 10 pprn solution of 25 elements. A ten mL aliquot of the 10 pprn

standard then was used to make 100 rnL of a 1 pprn solution. These two standards then were

used to caiibrate the instrument. The correlation coefficient for the instrument was 1.0000.

3. 5.3 Electronic balance

The electronic balance used , supplied by Van Waters and Rodgers, was a mode1

ACCULAB # VI- 3MG. The readability was 1 mg. The sensitivity was 0.003 g over the full

range of measurement of 0.000 - 3 10.000 g. A 200.000 g calibrated weight was used to verify the

accuracy of the machine before and after each use.

3.6 Analyses

Attempts to use a volumetnc method of analysis for the detemination of nickel had to be

abandoned due to interferences caused by the ieaching reagents ammonium sulp hate, ammonium

hydroxide and ammonium citrate. Attempts to use üV spectroscopy to analyse the extracted

solutions was not able to discriminate between the three different element's amine complexes well

enough to accurately determine the relative arnounts of each element, nor the total amounts of al1

elements. This was due to overlap of the absorption spectra of the ammine complexes of each of

the elements.' '"

Atomic absorption spectroscopy was anempted and found to yield excellent results, but.

due to the large number of sarnples and the lack of an autosampler it was decided to use ICP

analysis instead. ICP ( Inductively Coupled Plasma ) is sirnilar to AA in that the sample is heated

to a high temperature ( in an inductiveiy coupled argon gas Stream ) which ionizes the elements,

The ionized elements emit characteristic wavelengths of light, the intensity of which is

proportional to the amount of the element in the sample. The ernitted light is focused on a

difiaction grating which separates the beam into separate wavelengths of light. The amount of

light of each wavelength is then determined by computer analysis of a ccd ( charged coupled

device ) detector output. The levels are compared to the set of standards used to calibrate the

machine. The ICP analyser has a linearity of five orders of magnitude and can accurately measure

quantities of unknowns from ppb to pp ten thousand depending on the calibration setup. Samples

were diluted to the ppm range as a suitable method for the analyser had been previously

established for elements at that concentration.

4 RESULTS AND DISCUSSION

4. 1 Effect of Leachant on metal solubilitv

A set of timed expenments over 5 h with sarnples being taken hourly was initially

conducted. The plot of metal extracted vs time indicated that a maximum was reached at 2 h.

Therefore a 2 h reaction time was used for most of the experiments. Initiaily single reagents

ammonium hydroxide, ammonium chloride, ammonium sulphate, ammonium citrate and

ammonium acetate were used to leach the INCO filtercake. Later, combinations of ammonium

hydroxide with ammonium sulphate, ammonium chloride, and ammonium citrate were tned, to

see if there was any benefit obtained by adding ammonium hydroxide to the ammonium salt

leachants. PH rneasurements were made for the sait only experiments and the result was t hat the

pH changed very little from values of 7 to 8 for the different salts. The addition of ammonium

hydroxide raised the pH of the solutions significantly in the range between 8 at the low

concentrations to 9.5 with the addition of 50 mL of 27 % ammonium hydroxide. The effect of pH

changes the ammonium hydroxide concentration. The formation constant for the hexamine

complexes i.e. K, Ni( MI,), = 539 .

Ni" + 6 w40H < ------ > Ni( NH,)," + 6 50

6 Ni( Mi,), = 539 = [ Ni( MI,),'+] / [ Ni"] x [ Mi40H l6

The high concentrations of ammonium salts and ammonium hydroxide used ennire that the

NH,OH concentration changes very little and the activity of NH,OH will also change very little as

a very small amount of ammonium hydroxide is consumed in forming the ammine complexes. The

effiect on the hexamine complex is far overwhelmed by the ammonium ion and ammonium

hydroxide concentrations. The reactions are limited by the solubiiïty of a species rather than by

equilibnum control. The concentrations of the metal amine complexes were at levels less than

0.5 % of their maximum values in the concentrated ammonium salt and ammonium hydroxide

solutions.

4. 1. a Ammonium Hydroxide

The results of a 2 h leach using vaiying amounts of ammonium hydroxide per mole of the

desired metals copper, nickel, and cobalt are plotted in Fig. 1 below.

Fig 1 Metals Dissolved Using Ammonium Hydroxide ai Room Temperature for 2 h

O 10 20 30 u) 50 Hl 70 80 9(]

Moles of Ammonium Hydroxide per mole of metals

The results of the ammonium hydroxide leaching for 2 h at room temperature were that a

smail portion of the nickel and cobalt, 6.8 and 2.7 percent respectively, and 30.8 percent of the

copper were dissolved.

4. 1. b Ammonium Sulphate

Ammonium Sulphate is the least soluble of the ammonium salts tned, and equivalent

quantities of other salts were used as a basis for comparisons. The results of a 5 h ammonium

sulphate leach are shown in Fig. 2 below.

Fig. 2 Percent Metal Dissolved Using Various amounts of Ammonium Sulphate

O 5 10 15 20 23 30 35 40 45

Moles of Ammonium Sulphate added per mole of metal in sampk

The copper at 48.4 percent solubilization is 66 percent higher than obtained with the pure

ammonium hydroxide. There is better than a 100 percent improvement over the use of

ammonium hydroxide with the percent of nickel solubilized tnpling to 21.7 percent and that of

cobalt tripling to 9.3 percent. Note'

1 The ammonium sulphate reaction ran for 5 h as opposed to 2 h for the other extractions.

4. 1. c Ammonium Chloride

Ammonium chlonde was tned with varying arnounts to match the equivalents of the

ammonium sulphate used. The quantities used were based on the actual mole fraction of the

metals contained in the waste sample. Fig. 3 below is a plot of the results.

Fig 3 Metal Solubilized using Ammonium Chloride 2h

O 10 20 30 40 50 60 'O 90

Moia Ammonium Chtotidc Pm Mdc . M d

It is seen from Fig. 3 that there is an irnprovement in the amount of the rnetals dissolved

compared to the ammonium hydroxide leach. The copper is highest at 40 percent, followed by

nickel at 1 1.1 and cobalt at 4.2 percent dissolved. The improvements are not as great as the 5 h

ammonium sulphate leach but still substantial cornpared to the 2 h ammonium hydroxide leach.

4. 1. d Ammonium Citrate.

Ammonium citrate, unlike ammonium chioride and ammonium sulphate, is the salt of the

weak acid ( citric acid) and ammonium hydroxide which is a weak base. It dissociates in water

and its ions c m react with hydroxyl or hydronium ions; consequently it becomes a buffenng

agent. Citric acid is known to be used in the electroless plating industry.' 16' for solubizing nickel;

therefore, it was thought that using ammonium citrate might yield usehl data when compared to

ammonium chlofide and ammonium sulphate. Fig. 4a below is a plot of the ammonium citrate

extractions.

Fig 4a Metals Dissolved by Varying Amounu of Arnmouium Citrate in 2 h

A O

O 2 4 6 8 10 12 14

Moles of Ammonium Citrate added per mole of Metab

The extraction using ammonium citrate very rapidly reached a maximum afîer 6 moles per

mole of metals was added, and appeared to taper off and decrease, however, the decrease is

w i t h the range of experimental error of + 3 % and may be an anefact.

The maximum values of the extraction for ammonium citrate were 78, 70, and 62 percent

respectively for copper, nickel, and cobalt. These values were al1 higher than previous results. The

extracted value for copper was 63 percent higher using ammonium citrate than for ammonium

sulphate. However the differences for the nickel and cobalt were some 500 percent for nickel and

an astounding 930 percent increase for the cobalt extraction. Ammonium citrate also dissolved

450 mg of iron as well as the other metals. The iron levels dong with the acnial solution ppms of

nickel are plotted in Fig. 4b for cornparison purposes.

Fig. 4b Concentrations of Metals In Solution

O 2 4 6 8 10 12

Moies of Ammonium Citrate PerMole o f Metals

The maximum iron concentration is over 1800 ppm. The high iron levels led to some

difficulty in separating the solids and liquids because, as the retained solutions becarne less

concentrated in ammonium salts, some iron precipitated as colloidal ferric hydroxide. The iron

value may be unreliable due to the high levels; nevertheless, it does point out a potential problem

with the use of ammonium citrate. Ammonium acetate next was investigated to see the effect of

using a mono carboxylic acid ammonium salt as opposed to the tri-carboxylic ammonium citrate.

4. 1. e Ammonium Acetate

Ammonium acetate in solution acts as a buffering agent, as does the ammonium citrate,

since both its ions, acetate and ammonium, will react with either excess hydronium ions or

hydroxyl ions. The results fiom the 2 h reaction with ammonium acetate are ploned in Fig. 5

below.

il 00 :O 00 au0 6000 8000 100 00 120 IJO lM OO

Mokes of ammonium Acetate per moie of metals in rample

Fig. 5 Percent Metd Dissolved Using Various amounts of ammonium Acetate

I iUJ

90 -

The maximum values for extracted metals are 66, 38, and 27 percent respectively for copper ,

nickel, and cobalt. The extraction results for copper, nickel, and cobalt are midway between the

values for ammonium sulphate and ammonium citrate leaching. Iron was not dissolved by the

ammonium acetate.

80

2 70 '

i

I

- R c m t Cobolt Disolvcd Y *Percent Nickel ~ I v d

9 - /--

Next a set of experiments using the maximum concentration of ammonium sait with

varying quantities of ammonium hydroxide was carried out. Ammonium sulphate, ammonium

chloride, and ammonium citrate were used.

1. 1. f. i Ammonium Sulphate with added Ammonium Hydroxide

First a fixed quantity of ammonium sulphate was used ( 47 .9 g ) which was the maximum

amount soluble for the conditions, and corresponded to 36 moles of ammonium sulphate per mole

of metal in the sample. Fig 6 below is a graph of the percent metal dissolved vs ammonium

sulphate with added ammonium hydroxide for a 2 h reaction.

Fig. 6 Metals Dissolved Using 37.4 moles of af Ammonium Sulphate

per mole of metals with varying ratios of Ammonium Hydroxide

Pacmi C a r Di.iolved

APaœnt Nickel Dudved

Moles o f Ammonium Hydroxide added per mole of Metals in Sample

There is a quick rise to a maximum for al1 three rnetals and then the curves flatten out. The

maximum for ail three metals occurs at the sarne quantity of ammonium hydroxide added,. namely

18 moles of ammonium hydroxide per mole of metal in the sample. Next a fixed amount of

ammonium hydroxide was used with varying arnounts of ammonium sulphate added.

4. 1. f. ii Ammonium Hydroxide with Added Ammonium Sulphate

This set of expenments used a fixed quantity ( 50 mL of 15.9 M ) of ammonium hydroxide

with the addition of various amounts of ammonium sulphate. The plot of the results is shown in

Fig 7 below.

Fig 7 Metal Dissolved Using 80 Equivalents of Ammonium Hydmide and Varying amaunts

of Ammonium Sulpbate per Mole of Metab In samplc

n q 10 15 !O 3 10 $3 10

.Vola of Ammonium Sulphate Pcr M o k or Metah in Sample

Here we see a simila. trend towards a maximum extractabiiity for each metai with the copper

reaching a plateau first. Nickel and cobalt slowly climb to a maximum later with aimost identical

later stage curves. Note ' A similar cornparison next was done for the ammonium chlonde

ammonium hydroxide system.

.)

The last points on this graph were taken h m the results of the previous experiment as were the starting

values taken from the work on the ammonium hydroxide extraction.

4. 1. g. i Ammonium Chloride with added Ammonium Hydroxide

The ammonium chloride expenrnents were pattemed after the ammonium sulphate

expenments. A fixed 72 moles of ammonium chloride per mole of metal was the starting point

and varying ratios of ammonium hydroxide were added. The results are shown in Fig. 8 below.

Fig 8 Percent Metal Dissolved using 38.9 g of Ammonium Chloride

100 with varying amounts of Ammonium Hydroride

Moles of Ammonium Hydroxide added per mole of metal in samples

The results for this set of experiments parallels those of the ammonium sulphate

experiments shown earlier, with the copper quickly reaching a slowly rising plateau d e r 20

equivdents of ammonium hydroxide was added and 70 percent of the copper had been leached.

Thereafler the amount of copper leached slowly rising to a maximum of 77 percent at an addition

of 80 equivalents of ammonium hydroxide. The cobalt and nickel foliowed the trend of copper

with a slower climb to 30 percent at 32: 1 moles of ammonium hydroxide added per mole of metal

and from there a slow steady clirnb to 40 percent dissolved for both cobalt and nickel at 80 moles

of ammonium hydroxide added per mole of metais in sample.

4. 1. g. ii Ammonium Hydroxide with added Ammonium Chloride

A continuation of the ammonium hydroxide and ammonium chloride extractions was the

use of a fixed arnount ( 80 moles of ammonium hydroxide ) per mole of metal with varying

amounts of ammonium chioride added. The results of these experiments are s h o w in Fig. 9

beiow .

Fi 9 Metal Dissolved Using 80 Moles of Ammonium Hydroxide and Varying

Amounts of Ammonium Chloride Per Mole of Meta1 in Sample

The trend to a maximum continues and the curves almost duplicate those of the

ammonium sulphate with added ammonium hydroade reactions. Copper is the most soluble at a

78 percent with cobalt and nickel dissolving approximately half that amount at 40 percent each.

Next ammonium citrate with varying amounts of ammonium hydroxide was inveaigated.

4. 1.h Ammonium Citrate with added Ammonium Eydroxide

A series of experiments using 12 moles of ammonium citrate with varying amounts of

ammonium hydroxide was mn for 2 h at room temperature and pressure. The results are shown

below in Fig. 10.

Fig 10 Metal Dissolved using 12 Equivdents of Ammonium Citrate with

Varying amounts of ammonium hydroxide

Equivalents of ammonium hydroxîde per mole of total metals in sample

'O

JO

The addition of ammonium hydroxide to the ammonium citrate had no effect, as clearly

can be seen from the above graph. The respective amount for each metal extracted is the same in

.

al1 cases. The above graph demonarates the lack of effect of additionai ammonium hydroxide

1 PercentCqpsds4va l

8 P u a n t Cobait Duiolvcd -&- Perant Nickel Diuolved

when used in combination with ammonium citrate.

This can be explained by the pka of the citric acid which is a weak tri-carboxylic acid. The

ammonium citrate is completely dissociated in water. The respective ions react with water and

form the acid and base. The fiee ammonium ion can take up the excess hydroxide ion to form

ammonium hydroxide.

Note '

The overall reactions end up producing ammonium hydroxide in situ and therefore any

additional amounts would be superfluous and there would be no advantage of adding extra

ammonium hydroxide. The ammonium acetate behaves in a similar fashion.

4. 1. i Surnmary of Different Leachants

It was found that there were maximum arnounts of metd leached for each leachant. The

worst case was with ammonium hydroxide which leached very small proportions of the most

valuable materials cobalt and nickel. The overall best leachant thus far is the ammonium citrate,

which kaches up to 83 percent of the copper, 70 percent of the nickel and 60 percent of the

cobalt. The pH of the ammonium citrate solution was 7.5 at the low concentration to 8.5 at the

hi& concentration. However, the ammonium citrate also leaches high levels of iron which none of

the other leachants does. This is due to the citrate ion being tri-dentate'? thus being able to

supply three electron pairs to the femc ion and chelate it extrernely well. It is clear from the above

that the use of ammonium hydroxide with either ammonium chloride or ammonium sulphate has a

synergistic effect in that more material is leached than can be accounted for if each matenal was

3 The stepwise ionization of citrate has been ignored for brevity

acting independently of the other. The maximum percentages that were dissolved are surnmarized

in Table 1 below.

Table 1

Percent Metal solubilized with different ammonium compounds

Tercent Copper Percent Nickel Percent Cobalt

Ammonium Hydroxide

Ammonium Chioride

Ammonium Sulphate

Ammonium Acetate

Ammonium Citrate

Ammonium Chloride

plus Ammonium

Hydroxide

Ammonium Sulphate

plus Ammonium

Hyd roride - -

Temp 2 1 C, ambient pressure, 2h,

The reagents in the above table were the maximum values used in the previous

expenrnents. The arnounts of ammonium hydroxide used in those expenments with ammonium

hydroxide were al1 50 mL of 30 % solution.

4 .2 Effect of Leaching Tirne

A series of extractions were canied out over 24 h for the four most effective leachants

from the short tenn leaching runs discussed in section 4.1. They were ammonium citrate,.

ammonium acetate, ammonium suiphate with ammonium hydroxide, and ammonium chloride with

ammonium hydroxide. The experiments used four separate flasks for each experiment so that

there was no loss of matenai when sarnples were taken. The times were set for 1, 8, 16, and 24

hours. The two hour values were taken from the previous results.

The results are s h o w on three separate graphs cornparing the same metal extracted with

different leachants. Fig 1 1 a is the copper extraction, Fig. 1 1 b is the nickel extraction, and Fig. 1 1

c is the cobalt extraction. The experiments were performed at room temperature ( 2 1 C ) and

atmospheric pressure. The reagents used were as follows

Ammonium Sulphate 47. 9 g Plus 50 rnL 30 % Ammonium Hydroxide Plus 57.2 g Slurry

Ammonium Chloride 38.9 g Plus 50 mL 30 % Ammonium Hydroxide Plus 57.2 g Slurry

Ammonium Citrate 50 mL of 2 M solution Plus 57.2 g slurry

Ammonium Acetate 87 g Plus 57 g slurry Plus 25 mL water.

Fig I l a Coppcr Extracted over 24 h with Different kachanis

Fig.11 b Nickel Earacted over 24 h with Different Leachants

Fi 11 c Cobalt Ertwcted over 24 h with Dlfferent hachants

3 -0 O

i - O

. - # . P 4

Paant Cohlt Durolved Sul@tiaic - Cl Paann Coboli Durolvcd Orionde

A P a m t Cobalt Diwlved Aœwc

Perunt Cdnit Duu>lvcd C i m

O I O I! 20 3

Time h

The experiments were performed at 21 C and atmospheric pressure.

The time curves for each salt behave similarly; the absolute values differ depending on the

reagents. The results plotted above show that mon of the material is dissolved in 2 h and that only

slight additional leaching occurs from 2 to 24 h. The time curves for each salt behave similarly;

the absolute values difEer depending on the reagents. This Iack of improvement with time could

have been the result of reaching a saturated condition.

To test this hypothesis second leaching experiments then were performed on several of the

previously-leached samples using identical reagent concentrations, conditions, and times as for the

first leach.

4.3 Secondary Leaching

Four previously leached residues tiom ammonium hydroxide with either ammonium

sulphate or ammonium chloride extracts were reacted using the identical reagents and conditions.

The samples had been first leached with 50 mL of 30 % ammonium hydroxide plus 47.9 g of

ammonium sulphate or the equivalent arnounr of ammonium chlonde.

.Table 2

Cornparison of fint and second leaches

1 Am Chl Oct 24 # 8 Cu 76 4 80 78

Experiment # And

Metd Dissoived

Am Chl Oct. 24 #7 Ni

Am Chl Oct. 21 # 8 Ni ,

Am Chl Oct. 21 #7 Co

Am Ch1 Oct, 21 # 8 CO

Am Chl Oct. 21 #7 Cu

Sulp Oct. 27 # 7 Co

Although there was some secondary leaching the results were low compared to the first kaches.

Percent Metai

First Extraction

45

43

43

12

78

Percent Metai

Second Extraction

6

8

Total Percent

Metal Ertracted

51

51

Percent Extracted

in 24 Rours

47

47

47

47

78

7

9

4

50

51

82

The above table demonstrates t hat a second leach can extract fiom 6 to I 1 percent more

than the first leachV4 but it only reaches a slightly higher maximum arnount of metal than can be

dissolved in a single 24 h leach. It cm also be seen that the total values for the first and second

leaches are the same for a particular ammonium salt and ammonium hydroxide set. This would

suggest that. since not al1 the metals were dissolved in the second leach. some fraction of the

metals are in different compounds which are less soluble. That is, there are two different

compounds for each metal in the waste product. The effect of heating on the extractions using

ammonium sulphate, and ammonium chloride next was investigated to see if heating made the

materiai more soluble.

4.4 Effect of Heating

A weighed quantity of slurry was placed in a 500 m . three neck round bottomed

reaction flask equipped with a magnetic stirrer, a thermowell and a reflux condenser. The flask

was secured in a water bath which was heated using a hot plate magnetic stirrer combination. The

ammonium salt and ammonium hydroxide was added, heating started and well rnixed samples

were taken at 1, 2, and 5 hours. The solution boiled at 78 C. because of the high concentration of

ammonium hydroxide in the solution. The sarnples were well mixed throughout the experiment.

The solution volume changed with time as ammonia escaped, therefore it was decided to

separate the pregnant solution fiom the solids for each sample, wash out and collect the retained

solution and then digest the washed sample residue. Analysis of the extracted solution and the

residue digest would give a total quantity of metal for each sarnple and thus a relative percentage

f Both first and second leaches were for 2 h at room temperature and atmospheric pressure.

The 24 h values are included to demonstrate the maximum leached for the same reagents.

3 1

extracted could be calculated. The mass balances for the total metals was between 95 and 10 1 %.

The results of the 5 h heating are plotted in fig. 12 below.

Fig 12 Percent Metal Dissolved witb heliting up to 5 h

1 I 1 4 9 6

Time ( h )

The maximum amounts dissolved were reached in 1 h versus 2 without heating.

The above plot shows that the curves for copper are almoa identical at 84 percent and

that the cobalt and nickel cluster around 60 percent. Heating at 78 C did not increase the amount

of the metals solubilized to any appreciable extent. The dmost identicai curves indicate that both

the ammonium sulphate and ammonium chlonde with added ammonium hydroxide are equaily

effective leachants for this material.

4.5 Effect of Ageing

Cunosity led to dissolving some pure nickel hydroxide in the ammoniacal ammonium

sulphate. A four year old sample of purified nickel hydroxide was used. A leach of the aged nickel

hydroxide, which used 47.9 g of ammonium sulphate and 50 mL of 30 % ammonium hydroxide at

2 1 C, and which ran for 24 hours, lefi a Fraction of insoluble materiai that had the same

appearance as the original nickel hydroxide. This material was soluble in dilute ( 0.1 N )

hydrochloric, sulphunc, and nitric acids.

It was suggested , by Dr. George Babjak at MCO's Sheridan Park Research facility, that

the insoluble compound in the aged nickel hydroxide could be a basic salt of the type.

('NiOH)2S0,

Basic salts are known' '" and can be insoluble in water and basic solutions, but are soluble

in acids. However upon dissolution of the insoluble material in 10 % HCL and testing for sulphate

using a barium chioride solution there was no precipitate; therefore the insoluble matenal could

not be a basic salt, since it had been made fiom nickel sulphate. If it were a basic salt then a

precipitate of bariurn sulphate would have ensued fiom the barium chloride addition.

Nea a sample of fresh nickel hydroxide containing 5 g of nickel was added to a flask

containing 47.9 g of ammonium sulphate in 50 mL of water. The nickel hydroxide was observed

to slowly dissolve and colour the solution blue. When 50 rnL of 30 % ammonium hydroxide was

added the solution cleared before the addition was completed. The freshly made nickel hydroxide

was completely soluble in the ammonium sulphate and ammonium hydroxide mixture. This was

expected and confirms literature finding~."~ )

The jack of confirmation of a basic sait combined with the insoluble fraction in pure nickel

hydroxide led to discussions with Dr. John Graydon, of the department, regarding ways to

determine if there is an aged matenal present . It is known that ageing' " ' of transition metai

hydroxides does occur. Thennogravimetnc anaiysis was suggested as a possible way to detemine

whether there was an aged product present.

4.6 Thermogravimetric Analvses

Thermogravimetry as the narne implies is the use of heat to cause changes in the weight of

a sample. If there is a component of a systern that can be volatilized by heating the weight of the

remaining substance can be monitored. The temperature of the material will change over tirne but

there will be plateaus where energetic processes are taking place, such as the dehydration of a

hydrated salt. A sarnple of washed but othedse unreacted MC0 filtercake, and a well leached

and washed sample were analysed by Dr Graydon.

One of the problems with thermogravimetry is the small sample size; this makes it difficult

to monitor changes for relatively rninor components of a sarnple. The metal hydroxides in our

sample made up little more than 3 percent of the sarnple weight.

The graphical output is show below.

, Fig 13 Thennogram 1

Untreated INCO Matenal

Fig 14 Thennogram 2

Leached INCO filtercake

The derivative of the thennogram of the unleached material has a smail maximum which is

absent fiom the derivative of the thermogram of the leached materiai. This is an indication that

the leaching is removing ail of the materiai associated with that maximum.

Dr Graydon confirmed that a thennogram of a sarnple of the purified 4 year old nickel

hydroxide indicated that it had a sirnilar maximum. A thermogram of freshly made nickel

hydroxide aiso showed the same maximum. The occurrence of the maximums at the same

temperature indicates that a sirnilar process is taking place at that temperature. We can conclude

that the three materials contain the same substance. This may help explain the inability to dissolve

al1 the metal compounds since al1 of the material that causes the maximums is in fact solubilized.

Dr. Graydon also confirmed that a thermogram of the older purified nickel hydroxide was

found to be sub-stoichiometric for nickel hydroxide because the weight loss. at the temperature at

which hydroxide loses water to form oxide, was less than the expected arnount for the quantity of

material analysed. This helps to confirm that there are at least two different compounds in the

material.

As mentioned above, it is known that transition metal hydroxides, including nickel, age.'"'

Ni(OH),> NiO. H,O - - - > Ni0 + &O

The nickel oxide is thermodynamically more stable than the hydroxide and over time the

hydroxide will convert to oxide. This is true of al1 transition metal hydroxides and their respective

oxides.'"' The use of ammonium hydroxide and ammonium salts to separate the ammonium

hydroxide insoluble aged products from the soluble nickel hydroxide may be of some use in

investigation of the phenomena of copper, nickel, or cobalt hydroxide ageing. The possibility

that ageing had an effect on the solubility of the waste suggested that evaluating differently

treated materials might yield some information on the waste.

4.7 Plant Processine Conditions

The MC0 material is filtered using a rotary vacuum filter which draws tremendous

volumes of air through the cake. This may partially dry the cake and make the end product oniy

partially soluble in the ammonium sait solutions.

Sarnples of a 7 day old filtercake, dong with samples of influent and filter pre-feed were

obtained. The 20 L of influent was treated with 120 g of calcium oxide and the precipitate was

collected after decanting the supernatant. It then was centrifuged and transfemed to a 250 mL

erlenrneyer flask for reaction. The pre-feed was shaken to mix it thoroughly, two 100 mL samples

then were centrifuged to remove the excess solution. Samples of the 7 day old matend were aiso

taken. As well a sample of the 5 year old matenal was digested in 5 M sulphuric acid and then

reprecipitated using lime.

Each of the samples then was reacted with 47.8 g of ammonium sulphate and 50 mL of

concentrated ammonium hydroxide for 2 h at 22 C. The samples then were centrifuged and the

residues washed and the washings collected. The respective pregnant solutions and washings were

CO-mingled and diluted to 250.0 rnL for anaiysis.

The washed residues of the above materials were al1 digested in concentrated Ntnc acid,

the digests were centrifuged and the clear solution decanted. The residues from the digests then

were washed and the solutions added to the clear digest and diluted to 250.0 mi,.

Table 3 below is a cornparison of the results of processing conditions on the leachability of

the metals.

Table 3

Extractions of different precipitates of 16 g solids

47.9 g ammonium sulphate with 50 mL of 27 % ammonium hydroxide

II Type of Rcsidue 1 % Copper Dissalveci / % Nickel Dissolved 1 % Cobalt Dissolved

7 Day Old Cake 1 94 I 81 I 55

Old Cake

Note '

Copper is little affeaed by the age of the materiai whereas cobalt is the most affected.

Ufiltered prefeed and re-precipitated material behave simiiarly for al1 three metals. The seven day

old cake was dmost as good as the ufiltered pre-feed materiai for copper and nickel extraction

but was only slightly better for cobalt than the five year old material. The laboratory preparation

of material using lime as a precipitant was not as good as for the re-precipitated material even

though both products were made using the same reagents and following the same protocol.

From the results obtained there is clear evidence that the metals are precipitated as their

hydroxides and that by the time they exit the rotary vacuum filter they have aged sufficiently to

render a portion of each insoluble in the ammonium hydroxide ammonium salt solutions at

atmospheric pressure and with limited ammonium hydroxide present.

1 l

- - - - - - - -

82 50

5 The experimental volumes were 130 mL each

39

48.1

The MC0 material is first precipitated in very large 1,000,000 L reactors and as a resuit it

will have aged for several weeks before it is filtered. This may explain why 12 percent of the

nickel and 24 percent of the cobalt is not removed fiom the pre-feed material.

The lower levels of cobalt leaching as compared to the nickel, rnay be explained by the

observation that wet cobaltous hydroxide formed a dark higher oxidation product when it was

shaken in air as happened with a sample of fieshly made pink cobaltous hydroxide that was being

washed in the \ab.

The ageing process may change the hydroxide Me ( OH ), to a metal oxide hydrate with a

formula MeO. H.O. This is an interesting question and the use of an ammoniacal ammonium salt

solution may be a way to separate that component of an aged system, at least for copper, cobalt

and nickel hydroxides.

The inability of the ammonium hydroxide / ammonium sulphate mixture, which clearly

dissolves nickel hydroxide, to completely dissolve the nickel fraction fiom the waste matenal

leads one to conciude that there are at lest two distinct nickel containing chernical compounds

present. The aged nickel hydroxide may explain why there is an insoluble fraction but it does not

prove that the insoluble compounds in the waste are a result of ageing of the hydroxide

precipitates.

M e r the leaching investigation a prelirninary investigation of the practicality of using an

electro-reduction to recover the metais from the ammonium sulphate solution was investigated.

4.8 Electro-reduction

4.8. 1 Electro Stripping

This experiment was to demonstrate the practical ability to remove the copper, nickel, and

cobalt frorn solution and to thus be able to recycle the barren Ieaching solution so formed. Table 4

beiow is a tirne vs % removal of the three metals.

Table 4

Electro-reduction of metals in ammoniacal ammonium sulphate solution.

V = 4.0 volts 1 = 0.5 amperes Measured at the electrodes

L

The above table resulted from an electroplating experiment by which ferrous ions were

dissolved from a steel anode and the copper, nickel, and cobalt ions were reduced and deposited

onto a stainless steel cathode. The dissolving ferrous ions were being oxidized by stimng the

solution in air. The air oxidation was continued for an additional ten hours. The ievel of iron in the

solution after precipitation of femc hydroxide was Iess than 1 ppm.

This preliminary experiment was done merely to dernonarate that the three met& could

be effectively stripped from an ammoniacal ammonium sulphate solution using an electroplating

technique and that the ferrous ammonium sulphate in solution, could be air oxidized to remove

Time h

O

24

40

Percent Copper

removed

O

98.5

99.9

Percent cobalt

removed

O

78

98

72

Percent nickel

removed

O

12

34

99 99.9 99

the iron as ferric hydroxide, which is insoluble in ammoniacal solutions' I9 ', leaving a regenerated

barren solution for recycling.

The effective process is that steel reacts with the copper, nickel, and cobalt hydroxides

plus oxygen to fom femc hydroxide and the metals. This will use less energy as it is easier to

oxidize iron than to oxidize water by almost a full volt.

The results from air oxidation of the ferrous sulphate in ammonium hydroxide were that

the intense blue colour had completely disappeared, indicating that the ferrous matenal had been

oxidized to ferric and that femc hydroxide had been precipitated. There was a noticeable build-up

of ferric hydroxide in the bottom of the beaker.

1.8. 2 Current Efficiency

The initial concentrations ( ppm ) of metais in solution were Ni 10,294 Cu 144 1

and Co 2065. Solution volume 500 mL volumetric class A.

The molar quantities are 0.17755 mol Ni, 0.02268 mol Cu and 0.03 504 mol Co.

The current was 0.5 A for 72 H. Therefore 72 X 3600 X 0.5 C = 129600 Coulombs.

96,487~ Moles of bivalent metal are 0.2353 and requires 0.2353 mol x (5) x (F-) = 45 40 1 C . 45,JO l c Therefore the current efficiency (-) x 100 = 3 5 Percent.

This investigation was preliminary and was an attempt to demonstrated the practicality of

electro-reduction to remove the metals. The development of an electrolytic recovery is

recommended.

5 CONCLUSIONS

1. The use of an ammoniacal ammonium sulphate or ammonium chloride solution to

extract the copper, nickel, and cobalt fiom freshly made or non vacuum filtered M C 0 waste has

some merit and may have some application in industry.

2. The waste as produced yielded lower solubility than waste that had not been vacuum

filtered. Also, the older waste had a markedly reduced solubility of the nickel and cobait fractions.

3. Ammonium citrate, while an excellent leachant, aiso dissolved the undesirable iron

component and was aiso heat sensitive; therefore it is not recomrnended as a leachant for this

product .

4. Heating the solution at atmosphenc pressures had no advantage in solubilizing the metal

components.

5. A two hour leach effectively dissolved most if not al1 of the soluble components of the

waste.

6. The use of an electroplating process utilizing iron to replace the copper, nickel and

cobalt in solution would ailow for the leaching solution to be recycled, since the iron then could

be precipitated and removed with the leached residual waste.

6 RECOMMENDATIONS

1. Further work should be performed on developing an effective electrolytic recovery

system for the ammoniacal ammonium sulphate solution. The nature of the ammoniacal cornplex

changes the nature of the system with reference to electrode reduction voltage characteristics of

the metal.' "

2. The use of membranes to keep the anolyte and catholyte separated to reduce the

possibility that iron could CO-deposit with the other metals should be investigated.

3. A high temperature and high pressure ammonium hydroxide and ammonium sulphate

leach for the aged material rnay lead to a viable process for the recovery of the wastes that have

been stockpiled.

4. Investigation of the nature of the insoluble aged nickel with ammoniacal ammonium

sulphate may help understand the ageing of transition metal hydroxides better.

7 REFERENCES

Environmenta1 Protection Act Ont., Section 309

Atlas of Electrochemical Equilibria in Aqueous Solutions. M. Pourbaix NACE

Data Collected FFom survey that the author compiled in 1994

Meta1 h m i n e Formation In Aqueous Solution, J. Bjemm P. Haase And Son 194 1

Ammonia Pressure leach process for recovenng Nickel, Copper, and Cobalt from Shemtt

Gordon Nickel Sulphide Concentrate, F. A. Forward. Transactions Volume LVI 1952 pp

373 - 380

Mellor's Modem Inorganic Chemistry 1939, G. D. Parkes and J. W. Mellor

A. I. Vogel " A Textbook of Quantitative Inorganic Anaiysis " 3rd ed. Longmans.

Reduction of Nickel by Hydrogen from Ammoniacal Nickel Sulphate solutions. V N.

Mackiw. W. C. Lin, and W. Kunda. p 786 Journal of Metals 1957.

Ammonia, A. V. Slack 1973 Marcel Dekker Inc.

Ammonia Leaching of Nickel and Cobalt Ores, M. H. Caron Transactions AIME Vol.

188 1950 Journal of Metals 67

Chemistry of the Ammonia Pressure Process for Leaching Ni, Cu, and Co from Shemtt

Gordon Sulphide Concentrates. F.A. Forward and V. N. Mackiw Journal of Metals

Mach 1955 pp 457 - 463

Operation of a byproduct ammonium sulphate plant at Shemtt Gordon Mines Limited.

J. Stiksrna, R. Schech and M. McKimon Presented at the International Symposium on

Crystallization and Precipitation, Saskatoon, Saskatchewan, Oct 5 - 7 1987.

Metallurgical Improvernents in the Treatment of Copper - Nickel Ores. The Staff of

MC0 MME Journal of Metals vol. LI 1948 pp 187 198.

The Recovery o f Cobalt by The Soluble Cobaltic Arnmine Process, R. Stauffer and S.

Lindsay Presented at the Conference of Metallurgists of the Canadian Institute of Mining

and Metallurgy in Toronto, Ontario, August 29 - 3 1 , 1966.

Stability Constants of Metal Ion Complexes 1964, J. Bjemm The Chernical Society

London

Handbook of Electroplating 1999, American Electroplaters and Surface Finishers.

Basic lnorganic Chemistry 1976. F. A. Cotton and G. Wilkinson. John Wiley And Sons

Mellor's Modern Inorganic Chemistry 1939. G. D. Parkes and .J W. iMellor

Inorganic Chemistry 1894. G. S. Newth. lonmans Green And Co

Inorganic Chemistry 1967, R. T Sanderson, Reinhold Publishing Corporation

8 NOMENCLATURE USED

The following nomenclature was used

Sample weight

Sample Volume

Solids content

Solids in a volume

Analyte

Dilution Factor

Diluted Volume

Residue

place

Residue Digest

Total metals moles

means the weight of a sample used in a reaction

means the measured volume of a sample of slurry of known solids

content

means the fraction of solids in a given sample

means the theoretical dry weight of a sample based on dried

standards

means the analysed sample d e r dilution

means the amount the original sample had to be diluted by for an

accurate anaiysis to be performed

means the standard volume to which the extracts and digests were

diluted to (in most cases this was 250 rnL )

means the undissolved solids remaining afker a reaction had taken

means the solution obtained by reacting a residue with excess acid

means the sum of the theoreticai moles of the individual metals in a

sample based on ICP analyses of nitnc acid digests of dud

samples

Percent metai dissolved means the arnount of metal dissolved compared to the

theoretical amount in a given sample

APPENDIX A

Sample Calculations

- 1 - To calculate the weight of a metal dissolved where the residue was not digested

Weight dissolved = analyte concentration ( pprn ) X dilution factor X standard volume of

solution ICP (analyte ppm 9.43) X IO0 X 0.25 L = 235.75 mg

Weight in HNO, digest = ICP Value for HNO, Digest X dilution factor X Standard

Volume of solution = 9..78 ppm X 100 X 0.25L = 244.5 mg in digested sample of sluny

Metal Fraction per dry weight of solids

= weight of metal in digested sarnple / ( Sarnple wt of Slurry X fraction of solids )

= 244. 5 mg 1 ( 57285 mg X 0.29 13 = 0.0 146 metal fraction in dried slurry

Percent dissolved = weight of metai dissolved / weight in sample X 100

For a sample weight of 64.569 g with a solids content of 29.13 % and a metal fraction of solids

of 0.0 146 The ICP value might be 8.714 for a 100 : 1 dilution of a 0.250 L standard volume.

Weight dissolved = 8.7 14 ppm X 100 X 0.250 L = 2 17.85 mg dissolved

Weight in sample = weight of sarnple X solids fraction X rnetal Fraction in dried slurry.

Weight in sample = 64.569 X 0.2913 X 0.0146 = 0.2746 g

Percent dissolved = weight dissolved X 100 / weight in sarnple

= 2 1 7.85 mg X 100 / 274.6 mg = 79.33 Percent of the metal dissolved

-2- Where there was a residue digested the total weight of the metal is known

Weight in extract = analyte concentration ( ppm ) X dilution factor X standard volume of

solution

9.. 78 ppm X 100 X 0.2SL = 244.5 mg in digested sample of slurry

Weight in residue = ICP Value for HNO, Digest X dilution factor X Standard Volume of

solution

Total weight = Weight in extract + weight in residue digest

Percent Dissolved = Weight in extract 1 total weight X 100.

weight in extract =1 ICP Value 9.43 X 100 X 0.25 L = 235.75 mg

Weight in Residue Digest = ICP Value 2.43 X 100 X 0.25 L = 60.75 mg

Total weight = 23 5.75 mg + 60.75 mg = 296.50 mg

Percent Dissolved = 23 5.75 X IO0 / 296.5 = 79.5 1 .

APPENDIX B

TABLE OF 22 ELEMENT ICP ANALYSIS

A 22 element analysis of ammonium sulphate with ammonium hydroxide Expt 8 July 5 , 2000

Sample-lD Analyte 758 Ag 328.06 758 A1 308.21 5 758 As 188.97 758 Ba 233.52 758 Be313.10

Mean-ST -0.138 1 01 -0.050527 0.362958

-0.018548 -0.004961

RSD . Cal-Units Std-U 1 Std-U 2 1.151 mg/L -0.13781 1 -0.136675 3.337 mg/L -0.048582 -0.05 1 586 1.80I. mg/L 0.355643 0.368233 0.897 mjjL -0.01 8584 -0.01 8366 0.339 lm& -0.004975 -0.004942

Std-U 3 -0.139816 -0.05 14 12 0.364997

-0.0 18693 -0.004965

APPENDIX C

Raw ICP Values for the rnetals Copper Nickel and Cobalt

July 5 2000 Ammonium Sulphate with Ammonium Hydroxide

[Sample-I 1 Analyte Mean-ST RSD Cal-Units Std-U 1 Std-U 2 Std-U 3

119l61'f .E :69188f'E :Z ; ILE68f-E ; 1 ,EO-3tl'S SESISI'O .LIL16E'f !N 00'Za !?;'~LzL 5ESL09'C f SI CG97 ii: 16S6P19-f 1 1 EO-306'L 15 16101'0 (69ZS19'5 !N OO'SG !S;UZL 9628t.8'1 : f . L6LECS'I ;5 !86nE8'1 1 i €0'308'8 ; L Ob8ft'O ' t 9 18C8' 1 !N OO'ZCL !N'9LSf SSIûl6'0 f tlC696.0 :Z :ZIPL6'0 1 i EO-39S'Z SELC9Z'O ,LOSIL6'0 !E; OO'ZEi !NISLSL SbSl9f'O . E E86LSf.0 ;5 !91t19E'O 11 r EW38T'f I8LC806'0 . S 1 f 19f.0 !S OO'ZEZ !K itLSL 20'38L'L ' E ZO-3EI'L Ii: ;Z0-386'9 : 1 i EO-38t' l 8599LO-Z ;O-3E I 'L !K OO'SEZ !.h; i ELSL 20-38t.Y f ITO-30'2 IS iSO-3Sl.i: 1 1 'CO-3ZCC !8019t'01 mZO*XZT !N 00'Slc !SISLZL ZO-390'1 f CO'XS'6 ; Z 120-3CW1 : 1 : t i)-3tI 'S i S8P690.5 : 20-310'1 !N OO'SCi !.";' l LZL

ZIlS66'0 E 106686'0 ;Z ' 81 ES86'0 1 ; CO-306't i 6S6Mt'O 1 1066'0 03 19'8Zi: 03 8LSL 68MlL'O S E 161f9ZL'O If IZIZSZL'O 1 1 ! CO-318'C ! 186925'0 L08EZL.O 03 I9'8ZC 03 UZi ZEtSSt'O : C :t9IlSt'O ;Z ! 898ûSt.0 ! I 'fW3SS'Z I 18t49S'O .88tZSt'O 03 1 9'8X 03' 9LZL SOSZ 12'0 ' C I8ZLllZ'O iZ ItZllZ*O ' 1 .t@310'8 4108UE0 ~Sf6115'0 03 19.822 03 SLLL 20-3St.9 f sZ0-3X~9 ;Z 150-3L C'9 : 1 , EO-391' 1 ! 9ZOtE8' 1 ; 20'3PE.9 03 19'855 03 tLZL Z05?Sl'l E '20-3LZ I : Z 120-XI'1 11 i ti)-Xt.'9 1 L90SOt-'5 ' ZO-30;' 1 03 1 9'822 03 EL TL EO-Xt 'Z ' E I fV396‘1 :Z I CO-305'1 ! 1 I W3SO't I WLS'bZ €0-3L6' I 03 8 19'8SZ 03: SLSL EO-3S.Z- IWd30'f 1 CO-3t.Z- 100-30'5 I EO-31'2- I 1 I W-39L-1 I I SEWS'L i CO-3E.Z- 03 19'8ZZ 03 ILZL ,3) 3 ~ 3 ~ 1 r ; I W % ~ ? I O ) 3 ~ m ~ IWI(~!PD) ~ ~ ~ S I O N ~ h i ( q ! m ) as ~03) am ;m) 3 ~ 0 3 ~ 1 3 N a r i l w v ~ a l aldute

Ammonium Chloride with added ammonium hydroxide

Sample-1 Analyte Mean-ST RSD Cal-Units Std-U 1 Std-U 2 Std-U 3

Ammonium citrate with added ammonium hydroxide

Sample-1 Anaiyte Mean-ST RSD Cal-Units Std-U 1 Std-U 2 Std-U 3 720 1 Cu 324.75 9.142995 0.154 rndL 9.126801 9.149312 9.152873

APPENDIX D The raw ICP Values and the Respective Spreadsheets of Experiments The Tables in this section are used to calculate the percent of metal dissolved or removed February l e - 14 e

Ammonium Sulphate Extractions

kmplc Dilutcd Pcrant ldcnufiatio Slmplc Fnaion Gnatnuati Diluum SImplc H g GbJt C d d t n Eicmcnt Mcan-ST SD-Calib RSD Cal-Uni& Weighr g Mcul ai F a a a Vdume ûissdvcd D iudved march7-le Co 278.6 16 0.03251268 0.002031 6.167 m u t

Samptc-ID Analyre Mean-ST SD-Cdib RSD Cal-Unics march7-lc Ni 31003 0.11 11579 0.00343 3.M mg& march7-2c Ni 3 2 0 0 3 0,338261 0.005213 1.541 mgiL march7-3c Ni 31003 0.W18M58 0.006116 0.768 mgfL march7-k Ni 232003 1.3079563 0.006103 0.522 mg/L march7-5t Ni 233303 I W Q S I O.W327 O. 121 mg/L march7-k Ni 232003 2.7295044 0.015495 0.567 mg/L march7-7e Ni 23303 12.091665 0.074397 0.615 mg/L rnarch7-tk Ni 232003 18.969963 l). 115797 0.61 mglL

Sample Pcrant Dilution Volumc Mg Nidctl Nickel

Sid-U 1 Factor ( L ) Dissolved üissolvcd 0.0132 O. 114942 10 0.25 0.287355 0.130616 0.0132 0.342971 10 0.25 0.857427 0.38974 0.0132 0 .WW3 10 0.3 102JS07 0.9203 O.0132 1.306948 10 0.25 3.37371 1.485169 0.0132 1087527 10 0 . 3 5.218819 2.37219 0.0132 L%?28f 10 0.25 6.WMJ55 3.ü93M3 0.0132 12.Olm 10 0.15 30.04313 13.65597 0.0132 18.dSW7 10 0 . 3 47.t46û5 21.43002

March 19 Ammonium Chloride extractions

Experimen t Mar 19- 1 Mar 19 - 2 Mar 19- 3 Mar 19 - 1 Mar 19 - 5 mar 19 - 6 Mar 19 - 7 Mar 19 - 8

Dilution 10 50 50 50 50 50

100 100

Experirnent Analyte AauaI Mg of Perant Idzntificatio Dilution Sampie Copper Conanira Standard q p e r Cappcr in n Faaor wcighr Conc tion ppm volume dissolved Solution

PPm Cu Aaual Volume Mg's in 16.652 1.9 1 19.1 0.25 4.775 16.652 0.874 43.7 0.25 10.93 16.652 1.351 67.55 0.25 16.8875 16.652 1.638 81.9 0.25 $6.475 16.652 2.225 11 1 . 3 0.25 27.8125 16.652 1534 126.7 O . 31.675 16.652 3.42 342 0.25 85 5 16.652 4.481 448.1 0.25 112.0?5

Dilution Faaor for Co and Ni

Dilution Mar 19- 1 1 Mar 19 -2 1 O Mar 19- 3 10 Mar19-4 10 Mar 19 -5 1 O rnar 19 - 6 10 Mar 19 - 7 10 Mar 19 - 8 10

Dilution Mar 19 - 1 1 Mar 19- 2 10 Mar 19- 3 1 O Mar 19 - 4 1 O Mar 19 - 5 10 mat 19 -6 10 Mar 19- 7 1 O Mar 19 - 8 10

Analyie lobalt Auual Pcrtxnt Concentra Concentra Standard Mg Cobalt Cobalt lion [ion ppm VoIum dissolved Dissolvtd

Conc in Mg's Co PPM Co Sol'n Volume in Sol'n Perœnt

16.652 0.661 0.661 0.25 0.16525 0.2 16.652 0.047 0.47 0.25 O. 1175 O. 1 16.652 O. 102 1.02 0 . 3 0.255 0.3 16.652 0.143 1.43 0.25 0.3575 0.4 16.652 0.17 1.7 0.25 0.325 0.5 16.652 0.173 1.73 0.25 0.4325 0.5 16.652 0.904 9.84 0.75 2.46 2.7 16.652 1.812 18.12 0.25 4.53 4.9

Conc in Standard Perant in PPM Ni Sample Volum mg In soln Solution

16.652 1.9 1.9 0.25 0.95 0.4 16.652 0.308 3.08 0.3 1.54 O. 7 16.652 0.782 7.82 0.25 3.91 1 .8 16.652 0.9U 9.44 0.25 4.72 I I 16.652 0.778 7.78 0.25 3.89 1.8 16.652 0.961 9.6 1 0.25 4.805 -.. 9 9

16.652 3.219 32.19 0.25 16.095 7.3 16.652 5.214 52-14 0.25 26.07 11.85

Ammonium Citrate

Mg's in Soi'n

115.65 160.1

l69.n 193.8

197.55 IIrS17

-Tm33

Percen t Copper in Solution T'mu72

3 1.m 61.O6tTS

10.43 165 -7-mm3 -773m35

16.- 73;2554

Pcrccni Nickel in Solution 3.2 J4.5

J . - -IaO Y

39.3

7 36.6

'Moles Ammoniu m Citrate per Mole Metal

Copper in Solution

Perm t Cobalt in Solution D

7.0

3 4.3 43. r 94.0 60.7 66.4 69.5

Ammonium Sulphate With Ammonium Hydroxide

I 1 I

t Ihmiol m d -a l lUW#ls l l rq# lbmraml w h d

- b d d l -MC- I U o f C - dC-i- C d C U W u m e i m l & I 1 u?rip* 4 8 ) -- =iip*

O a137 O r OCMM flmlb 1 6 0 ~ -

O ml7 «,3llI / 0- O IR16 umir / o r n a - 0 m37 O (Rlb

1

O.O(U7 O,?l 1 U t m m O WI8 - omis 1 U a m '

n m n 0-WI I o a w omm o m i s 1 a m m 7 o w O 1 o m m 0 . m ~ ornia i aum.

Ammonium Chloride With Ammonium Hydroxide

Ammonium Acetate

Ammonium Citrate with Ammonium Hydroxide

Fnaian of Nickcl in Soli&

= 0.013: (1.013; m 1).013; 0.0f3;

nicorctia I Mda of Cobalt in Sample

7nmlm -Umm5 -omlm U.ODTS57 7Imm [IIWISn [lI1101568 O.W156

nicorciia 1 mola ot mdal in vmplc

-lJlmm -immla -lmmm -inmm O.W9685 -unFm -Umm m

Paœnt Cobal i

Dirtolvcd

63I3! T T -59.g? aI.Y = -7im

tual yc Conan tri iim ppn

Nickel ïE33m 6.16267,ç -inRZR 6.[]97CiS1 ï5lmm 7cmmT XxFm b.71KJS5;

aalpc Con a n in

tim ppm Cappcr

TRw -xm%3 -mmm ggn(JS7 V.102611 V.Z67PJ7 T+mm Tmm

24 Hour Experiments Ammonium Acetate

Smplc Thmct ia Identification Elcmenr Analyic Weighi l T o u l Thcœclia t\mmcmium & Ehmcni Concentra Anaiyic Nickel Soli& Ppm of weighr of I mole Percent Aatatc Mdytc wvelengr a d d tim ppm Dilution Vdume Durolved Waghi of Conicnt d mctal in mcul in ofmeul in Mcrai Extractions Numkr h for Meul Fa- ( L ) ( mg ) Emplc Emple Solids wmple m p l e Dirpolved I h am a m 16 Ni 31003Ni 3.7W836 100 0.15 976É091

Ammonium Citrate

24 h Ammonium Sulphate with ammonium hydroxide

Sarnple Identification Am moni um Sulphate with Ammonium Hydroxide Extractions 1 h am sulp 8h am sulp 16 h am sulp 25 h am sulp

Elernent Sr Element

Analyte wavelengt Analyseci Number h for

6 Ni 232.003 Ni 7 Ni 232.003 Ni 8 Ni 232,003Ni 9 Ni 232003 Ni

Anafyte Analyte Analyte Weigh t Concentra Concentrati Concentra Analyte Nickel tion pprn on ppm tion ppm Dilution Volume Dimlved Nickel Coppet Cobalt Faaor ( L ) ( m g ) 3.233%1 8.12668652 1.4035 1 100 0.25 80.84904 3.985885 9.09057034 1.715985 100 0.25 99.64713 4.247242 9.35844669 1.807734 100 0.25 106.1816 4.319696 9.41 160789 1.83755 100 0.25 107.9923

Theoretici Theoretica l Total Theoretica I Total

Weight of Solids Ppm of Ppm of PPM of weight of 1 moles of weight of Weight of Copper Cobalt Weight of Content of Nickel in Copper in Cobalt in nickel in nickel in Copper in dissolvcd Dissolved Sample Sample Sol ids sol ids Solids sample sample Sample

203.167163 35.234 57.962 0.29135 0.0132 0.0167 0.0055 0.2291 1 0.003802 0.282017 227.26125&1 42.900 57342 0.29135 0.0132 0.0167 0.0055 0.220527 0.003761 0.279 33.961 1 6 2 45.181 57391 0.29135 0.0132 0.0167 0.0055 0.220715 0.003765 0.379238 235.2901972 46.189 57.273 0.29 13s 0.0132 0.0167 0.0055 0.2û262 0.003757 0.278664

Theoretica 1 Total Theoretica weight of I Moles of Peraent Percent Percent

T7ieoteticaI Moles of Cobalt in Cobalt in Copper Cobalt Nickel Copper in Sample sarnple Sarnple dissolved Dissolved Dissolved

0.004438412 0.09288 0.001576 72.04 37.93 36.27 0.004390936 0.091 886 0.001559 82.46 16.69 45.19 0.004394688 0.091965 0.00156 1 83.79 49.13 $8.1 1 0.003385652 0.091 7ï6 0.001 557 84.43 5033 49.03

24 h Ammonium Chlonde with ammonium hydroxide

Smplc Idenlincation Ammonium Chloride with Ammonium Hydraxidc Exinctions 1 h am ch1 8h am ch1 16 h am ch1 24 h am ch1

A d p e Anaiyte Amiyte Weight Element Gncmuati Conccntrati Conantrati M y t c Nickel

N y t c Elemcnt & Analyscd on ppm on ppm on ppm Dilutiar Volume ( Dissalved ( Nurnber wavclcngth for Nickel Copper Cobalt Faam L ) mg )

1 Ni 32.003 Ni 3. 127884 7.836025 1.31 1523 100 0.25 78.19709 2 Ni 32.003 Ni 3.861 229 8.464101 1.6 19582 100 0.25 96.53074 3 Ni 332.003 Ni 3.876488 8.346 f 24 1.630079 100 0.25 96.9122 4 Ni 02.003 Ni 4.128037 8.685067 1.73 1632 100 0.25 103.2009

Theoretid Theoretical Total nieoreticai Total

Weight of Solids Ppmof Ppm of PPM of wcight of molcs of wcight of Weight of Coppcr Cobalt Weight of Content of Niclel in Coppcr in Cobalt in nickel in nickel in Coppet in drssolved Dissolved Sample SampIe Solids solids Solids samplc samplc Sample

195.9006262 32.788 57.03 1 0.291 35 0.0132 0.0167 0.0055 O.?lW3 1 0.003741 0,27487 21 1.603 132 40.490 58.676 0.29135 0.0132 0.0167 0.0055 0.225465 0.003846 0.285247 208.6531021 40.752 59.389 0.29135 0.0132 0.0167 0.0055 0.22399 0.003896 0.28896

217.12668 43.291 57.239 0.29135 0.0132 0.0167 0.0055 0.2201 3 1 0.003755 0.278499

Theorciical Toial Theuetical weight of Molcs of Perant Percent Ptrant

Thcoteticil Moles of Cobalt in Cobolt in Coppcr M a l t Nickel Coppcr in Sample sarnple Samptc -olvcd Dissolved DiJsolvcd

0.0043671 21 0.091388 O.Ool55 1 70.60 35.88 35.65 0.00J589258 0.093943 0.001594 74.18 13.10 42.81 0.004537684 0.095 166 0.001 6 15 72.21 42.82 42.43 0.004383049 0.09 1721 0.001 556 77.96 47.20 46.88

Heated Experirnents Ammonium Sulphate

u m5 urnb

um:

Heated Ammonium Chloride

Concctcd values Of

Mgs Nickel in solution 62.1 61.1 m -11.0 7 T

16.2 37.8 --3m3

Nickei

Sample dissolved 60.0 0.a

110.0 0.6f 300.0

Different Treatments

FreshCake and Lab Preps Sarnples

Solut ion Total Percent Analyte Element & Sarnple Fpm In Dilution Pprn in volume Mg Cobalt cobalt Numkr Wavelcngth Wemcnt Identification analytc factor solution ( 1 ) ûissolved ( mg ) d i d v c d

25 Co 28.616 Co ûec 27 1000 1nm 10.03365 4 40.17361 0 . 3 10.04 33.66214 57.5539049 29 C o 3 6 1 6 Co Dec 27 lnco exua 0.544739 100 54.47393 0.25 13.61 30 Co 28.616 Co Dec 27 Inca extra 0.61241 100 61.24103 0.3 153 1 26 Co 28.616 Co Dec 27 $000 Inn, 11.95955 4 51.83819 0.25 12.96 28.2698 54.15763 12 31 Co 28.616 Co ûec 27 Lab 2000 1.879618 100 187.9618 0 .3 46.99 27 Co 228.616 Co k c 2'7 2000 Lab 44.01632 4 176.0653 0 . 3 44.01 91.00678 51.633021 1 32 Co 228.616 Co Dec 2'7 300 Lab 1.59381 100 159.381 0.25 39.85 28 Co 228.616 Co Dec 27 2000 Lab 35.1 1644 4 140-4657 0.25 35.11 74.9617 53.1541613

Percent Cob Percent Copp Rrccnt Nickel Dissolved Dec 27 lnco c5755390402 93.68962702 8234763859 Dec 2'7 fnco e54.15763125 93.39482616 80.67185178 Dec 27 1OOO 53.15416132 Y6.81M8776 66.39477961 k c 2'7 ?Ooû 51.64102109 96.65454288 6 8 . 8 8 0 9 ~ 8

Solution Mg krccnt Pprn Coppcr in Volume Cappcr Total mg Coppe Solut ion ( L ) Dissotved Coppr Dtssolvtd

4.40017341 17.60069364 0.X 4.400173 69.71921 93.69963 Ni 233003 Ni 2.61316158 1613161581 0.25 6532904 Ni 232.003 Ni 3.15106529 315.1065192 0.25 78.77663 84.34796 9339483 Ni 237003 Ni 5.5713295 1 22.2853 1803 0.3 5.57133 Ni 237003 Ni 6.60897803 660.8978033 0.25 165.2245 170.6679 96.81049 Ni 232003 Ni 5.4347337 21.773897445 0.25 5.443475 Ni 137003 Ni 5.23083598 523.083598 0.25 130.7709 t35.2972 96.65354 Ni 233003 Ni 4.52631013 t8.10524051 0.25 4.52631 Ni 232003 Ni

Perceni M g Nichl in Solurion Mg Nickl Total Nickel Nickcl samplc Volume Dissolvcd ( mg ) Disolvcd

127.88192 0 . 3 31.97198 181.0688427 82.35264 596.38135 1 0.25 149.096863 70 1 ,200969 0.25 175.300242 217.3003823 80.67185

168.00056 0.25 42.00014 527.931384 0.25 13 1.982846 198.4860767 66.49478 266.0127îJ 0.25 665031807 456.WS9 0.15 1 14.012115 1655206513 68.8809 106.034 146 0.25 515085365

Dilution Factor

4 4 4 4

100 Io0 100 Io0