Bonding properties of mill waste tailings

T - 1 1 5 1

BONDING PROPERTIES OF MILL WASTE TAILINGS

By

Jozef R, Roos

ProQuest Number: 10781610

All rights reserved INFORMATION TO ALL USERS

The qu ality of this repro d u ctio n is d e p e n d e n t upon the q u ality of the copy subm itted.

In the unlikely e v e n t that the a u th o r did not send a c o m p le te m anuscript and there are missing pages, these will be note d . Also, if m aterial had to be rem oved,

a n o te will in d ica te the deletion.

uest

ProQuest 10781610

Published by ProQuest LLC(2018). C op yrig ht of the Dissertation is held by the Author.

All rights reserved.

This work is protected against unauthorized copying under Title 17, United States C o d e M icroform Edition © ProQuest LLC.

ProQuest LLC.

789 East Eisenhower Parkway P.O. Box 1346

Ann Arbor, Ml 4 8 1 0 6 - 1346

A thesis r e s p e c t f u l l y submitted to the Faculty and the Board o f Trustees o f the Colorado School o f Mines in p a r t i a l f u l f i l l m e n t o f the requirements f o r the degree of Master o f Science in

M e ta l l u r g i c a l Engineering.

Signed

Jozef R. Roos Golden* Colorado

Data: II / i S' , 1967

Approved:

Paul G. Herold Thesis Advisor

A. W. Schlech ten

Golden, Colorado

T - 1 1 5 1

ABSTRACT

The United States Bureau o f Mines sponsored t h i s work in the area o f s o l i d waste disposal. This work was aimed at t r y i n g to u t i l i z e mine dump and m i l l waste t a i l i n g p i l e s , which are so abundant in the state o f Colorado.

The waste materials were studied as a raw material f o r the

production o f b u i l d i n g products formed by the use o f low - temperature bonding a c tio n .

The materials from fourteen d i f f e r e n t t a i l i n g p i l e s were analyzed to determine t h e i r c on s ti tu e n ts . Atomic absorption

spectrophotometry was the most important analyzing technique used.

The r e l a t i v e s o l u b i l i t i e s o f s i l i c a in saturated solu tions

o f calcium hydroxide and o f magnesium hydroxide in water were determined.

Test bars were made with t a i l i n g s and calcium hydroxide as bonding agent. The bars were aged under various conditions and t h e i r strength measured. I t was found t h a t aging in steam at 125 C speeded up the strengthening mechanism g r e a t l y .

i i i

T-1151

I t was also found t h a t the two mechanisms f o r cementitious bonding, carbonation and formation o f hydrated calcium s i l i c a t e s , contributed in the same amount to the strengthening.

Construction b ric ks could be formed from t a i l i n g s and lime, using a steam curing treatment.

Also t e s t bars were formed with t a i l i n g s and a petroleum - based

binder. On aging at 110 C-f or ten days, the bars developed appreciable

s t r e n g t h . I n t h i s way, b u i l d i n g blocks of equal q u a l i t y to commercial

'concrete blocks could be produced. Such blocks also would be less

expensive to manufacture.

T-1151

TABLE OF CONTENTS

Page

ABSTRACT ... i i i

TABLE OF CONTENTS ... V LIST OF FIGURES ... ."... v i i i

LIST OF TABLES ... i x

ACKNOWLEDGEMENTS ... x

INTRODUCTION ... 1

REVIEW OF LITERATURE ... 3

MATERIALS USED AMD EXPERIMENTAL PROCEDURE ... 6

T a i l i n g s i n v e s ti ga te d and method o f s a m p l i n g 6 Chemicals u s e d 9 Moisture content o f the t a i l i n g s ... 10

Sieve analysis of the t a i l i n g s ... 10

Analysis by X - ray d i f f r a c t i o n ... 11

Chemical analysis by X - ray fluorescence ... 12

Chemical analysis by atomic absorption spectrophotometry. ... 13

v

T-1151

Page Preparation o f l i q u i d samples f o r atomic

absorption spectrophotometry . . ... 21

Determination o f the i g n i t i o n loss . ... 22

Density measurements ... 23

Preparation o f t e s t bars ... 23

Aging o f t e s t bars ... 24

Strength determinations . ... 25

'Determination of the water o f absorption ... 26

S o l u b i l i t y measurements by means o f o p t i c a l emission spectroscopy ... 27

EXPERIMENTAL RESULTS AND DISCUSSION ... 29

Moisture content o f t a i l i n g s ... 29

Results o f sieve analysis test s o f t a i l i n g s ... 29

Results of X - ray d i f f r a c t i o n analysis ... 33

Chemical analysis re s u l ts ... 33

Results of s o l u b i l i t y measurements ... 36

Strength re s u l ts f o r t e s t specimens with calcium hydroxide as bonding agent . . . 38

v i

T-1151

Page

Results from density measurements ... 44

Strength re s u lt s o f t e s t specimens with Peneprime as bonding agent . . ... . . . ... . 45

CONCLUSIONS ... ... 49

APPENDIX A ... 51

APPENDIX B ... . . . . ... 52 LITERATURE CITED... ... ... 5 4 “

vi i

T-1151

LIST OF FIGURES

Figure Page

1. The emission and absorption processes ... 15 2. Typical c a l i b r a t i o n curve f o r i r o n , calcium,

'magnesium, s i l v e r , and gold ... 18 3. Typical c a l i b r a t i o n curve f o r alum inum... 19 4. The autostandardization method ... 20 5. Modulus o f r u p t u r e - o f a i r - cured specimens,

versus a i r - curing time ... 41 6. Modulus' o f rupture o f 100 C - steam - cured specimens,

versus steam - curing time ... 42 7. Modulus o f rupture o f 125 C - steam - cured specimens,

versus steam - curing time ... 43

vi i i

T-1151

LIST OF TABLES

Table Page

1. T a i l i n g s in v e s ti g a te d in th i s study... 7

2. Moisture content o f the t a i l i n g s ... 29

3. Sieve analysis o f the t a i l i n g s ... - ... 31

'4. Chemical a n a l y s i s - o f the t a i l i n g s ... 34

5. Comparison between- wet chemical analysis by Wood Laboratories and the author's analysis . . . 37

6. Modulus o f rupture o f a i r - cured specimens, versus a i r - curing time ... 41

7. Modulus o f rupture o f 100 C - steam - cured specimens, versus steam - curing time ... 42

8. Modulus of rupture of 125 C - steam - cured specimens, versus steam - curing time ... 43

9. Unpacked density and packed density f o r f o u r t a i l i n g s 44 10. Strength o f t e s t specimens w ith Peneprime as bonding a g e n t ... . 1 ... 47

i x

T-1151

ACKNOWLEDGEMENTS

The author wishes to express his appreciation to

Dr. P. G. Herold f o r his i n t e r e s t and guidance during t h i s study.

Also the author is indebted to the United States Bureau o f Mines f o r sponsoring t h i s research.

x

T-1151 1

INTRODUCTION

Mine waste dumps and t a i l i n g p i l e s are very abundant in the stat e o f Colorado. When the gold rush came to an end l a t e in the nineteenth century hundreds o f mines closed down and l e f t a considerable amount o f the waste materials behind.

Mining and m i l l i n g operations today are producing thousands o f tons o f t a i l i n g s each day, thus adding u n s i g h tl y material to the scenery. For example: American Metal Climax, I n c . , at Climax, Colorado, re je c ts f o r t y thousand tons o f t a i l i n g s each day. Mot only is the scenery marred, but also the mining companies have to inve st huge amounts o f c a p i ta l in the disposal o f t h e i r t a i l i n g s .

The present study was aimed at t r y i n g to u t i l i z e these m i l l and mine waste t a i l i n g m a te ri a ls . This study was conceived as pr e li m in a ry th e o r e t i c a l work f o r actual forming o f various types of ceramic ware. The po rtion of the problem covered by t h i s thesis . was d e ta il e d as a study o f the waste ‘materials as a raw material

f o r the production o f b u i l d i n g products formed by the use o f

low - temperature bonding act io n.

T-1151 2

This would be s i m i l a r to the methods presently used in the concrete block i n d u s t r y , with or wit ho ut steam curing.

The study was also intended to include bonding by water - soluble

materials such as calcium hydroxide and magnesium hydroxide.

T-1151 3

REVIEW OF LITERATURE

To our knowledge the present study is new in i t s purpose:

t r y i n g to u t i l i z e mine dump and m i l l waste t a i l i n g s . C e rt a i n l y l i m i t e d studies have been done by several mining companies, but these i n v e s t i g a t i o n s were aimed p r i m a r i l y at s t a b i l i z i n g the t a i l i n g p i l e s .

The l i t e r a t u r e review which follows ref ers to the lime - s o i l and lime - s i l i c a re actions. Zalmanoff ( 1 , 2 ) and Taylor ( 3 ) considered carbonation and formation o f hydrated calcium s i l i c a t e s as the mechanisms f o r strengthening lime - s i l i c a m a te ria ls .

Zalmanoff (1) described the general conditions f o r the carbonation o f lime. The carbonation reaction is given as fo l l o w s :

Ca(0H)2 + C02 + H20 = CaC03 + 2 H20 + 19.6 kcal

T-1151 4

The reaction is heterogeneous inasmuch as a s o l i d , a gas, and a l i q u i d are on the l e f t hand side o f the equation. The p r e c i p i t a t i o n reaction i s most l i k e l y to occur in the l i q u i d s t a t e , due to the i o n i c c h a r a c t e r i s t i c s o f the p a r t i c i p a n t s . I f the reaction takes place in the l i q u i d s t a t e , the gaseous CC^ must undergo a s o l u t i o n i n g process which is another complex step. In the above re ac ti on , the reaction rate is c o n t r o l l e d by the a v a i l a b i l i t y o f CO^ and by the rate at which water can be removed from the system. Since the

na tural CO^ content o f the a i r is so low - only 0.05 % by weight (4) - the reaction proceeds ra th e r slowly.

Hall (5) found th a t calcium hydroxide mixed wi th a clay and cured in a steam atmosphere at 100 C developed very q u i c k l y the strength obtained only a f t e r allowing the carbonation reaction to take place in a i r f o r several weeks. Hall proved t h a t t h i s was due to the formation o f hydrated calcium s i l i c a t e s . This reaction also is l i k e l y to take place in the l i a u i d s ta t e . However, here water has to be provided f o r the hydration reaction to take p l a c e .r The hydrated calcium s i l i c a t e s formed in t h i s way were- found to be amorphous or very poorly c r y s t a l l i n e .

For a more de ta il e d d e s c ri p ti o n o f the mechanisms involved

in carbonation and formation o f hydrated calcium s i l i c a t e s , which

is beyond the scope o f t h i s work, see references 1, 2, and 4.

T-1151 5

I t should also be noted t h a t calcium hydroxide is used f o r the production o f s i l i c a b r i c k w h i c h is a r e f r a c t o r y m a te r i a l. The calcium hydroxide takes s i l i c a in s o l u ti o n and forms calcium s i l i c a t e

l i q u i d which, on d r y in g , acts as a glue ( 6 ) .

T-1151 6

MATERIALS USED AMD EXPERIMEMTAL PROCEDURE

T a i li n g s inv e st ig at e d and method o f sampling

The designation o f the t a i l i n g s used, t h e i r l o c a t i o n , the type of t a i l i n g , t h e i r age (estimated time on the p i l e ) , and the date they were taken are given in Table 1,

Some o f the t a i l i n g s were taken by the author, others were received from the Companies mentioned. The samples were taken at d i f f e r e n t places on the p i l e s so t h a t a f a i r l y representative sample was obtained. To get a b e t t e r representative sample o f a p i l e , d r i l l i n g would have been necessary. Indeed the composition o f the

material at the bottom o f the p i l e can vary somewhat from the composition o f the material at the top. This v a r i a t i o n in composition could be

caused by a change in m i l l i n g or mining procedures and/or by weathering.

However since the primary aim o f t h i s study was to i n v e s ti g a te

the materials in the t a i l i n g p i l e s as a preparation f o r the production

o f s t r u c t u r a l products, these r e l a t i v e l y small v a r ia ti o n s in composition

become unimportant.

T-1151 7 Table 1: T a i l i n g s inv e st ig at e d in t h i s study.

Designation Location Type Age(years) Date taken

Old Climax Climax, Colo.

Amax, Inc.

F l o t a t i on t a i l i n g

40 October 20,

1966

Young Climax Climax, Colo.

Amax, Inc.

F l o t a t i o n t a i l i n g

0 October 20,

1966

Naturi ta N a t u r i t a , Colo.

Vanadium Corp.

o f America

F l o ta ti o n t a i 1ing

0 November 18,

1966

Durango Durango, Colo.

Vanadium Corp.

o f America

F l o t a t i on t a i l i n g

0 December 15,

1966

Idaho Springs Idaho S prings, Colo.

Mine waste dump

80 October 20,

1966

Lead Slag Leadvi1l e , Colo.

Smelter slag dump

10 A p r i l 10, 1967

Si 1verton Si 1v e r t o n , Colo.

Mine waste dump

80 A p r i l 10, 1967

Ouray Ouray,

Colo.

F l o t a t i o n t a i l i n g

50 A p r i l 10,

1967

Table 1 ( continued ) : T a i li n g s in v e s ti g a te d in t h i s study.

Desi gnation Location Type Age(years) Date taken

Sav/ach L e a d v i l i e , Colo.

Mine waste dump

30 duly 20,

1967

Lower Denaro Leadvi 1 Te, Colo.

■Mine waste dump

o

!

duly 20, 1967

,

Iron Mask L e a d v i l i e , Cole.

Mine waste dump

30 duly 20,

1967

L i t t l e Jonnv L e a d v i l i e , Colo,

Mine waste dump

80 duly 20,

1967

El Capitan L e a d v i l i e , Colo.

Mine waste dump

80 duly 20,

1967

.. .. ..

i m

*

Leadvi1l e , Colo.

F l o t a t i on t a i l i n g

50 duly 20,

1967

■ k

F l o ta ti o n T a i l i n g s East o f L e a d v i l i e , Colo.

■T-1151 9

Chemicals used

Peneprime: inexpensive petroleum-based binder, commercial product from Empire Petroleum Company, Denver, Colorado. Mo analysis.

Pe rc h lo ri c acid (HCIO^): Baker Analyzed Reagent, Mo. 9652.

Contains less than 0.003 % i m p u r i t i e s .

H y d r f l u o r i c acid (HF): Baker and Adamson Reagent A .t C. S ., Code 1100.

Contains less than 0.006 % i m p u r i t i e s .

Potassium pyr osu lfate (i(9So07) : Baker and Adamson Reagent A. C. S..,

1 i- /

Code 2094. Contains less than 0,008 % i m p u r i t i e s .

Calcium carbonate (CaCO^) used f o r t e s t bars: commercial product from Mai 1in c k ro d t. Mo analysis.

Calcium carbonate (CaCO^) used f o r s o l u b i l i t y measurements:

M a ll i n c k r o d t A n a l y ti c a l Reagent 4071. Contains less than 0.001 % s i l i c a .

Magnesium oxide (MgO):■ M a ll i n c k r o d t A n a l y ti c a l Reagent 6015.

Contains less than 0.04 % s i l i c a .

. Calcium hydroxide was produced by c a l c i n i n g calcium carbonate at 1000 C and. reacting the r e s u l t i n g calcium oxide with d i s t i l l e d water. Magnesium hydroxide was produced by reacting magnesiurn

oxi de wi th d i s t i l l e d water.

T-1151 10

The p u r i t y of the chemicals was checked before use by X-ray d i f f r a c t i o n analysis.

The standard s o l u tio ns used f o r atomic absorption spectrophotometry were supplied by F i s h e r ' . S c i e n t i f i c Company and by Aztec Instruments, Inc.

Moisture con te nt o f the t a i l i n g s

250 g o f each t a i l i n g sample was weighed and dried overnight at 110 C, The moisture content was calc u la te d .b y the fo l l o w i n g expression:

250.0 - dry weight

% Moisture content = --- x 100.0 250.0

Sieve analysis of the t a i l i n g s

In order to determine the sieve analysis o f each t a i l i n g , 200 g of the dry materials were weighed and s t i r r e d in water f o r one hour.

3y washing the material through one sieve a f t e r the ot h e r, the

materials on T v l e r sieves 8, 10*14, 20, 28, 35, 48, 65, 100, 150, 200,

and 325 mesh were obtained. .

T-1151 11

The p a r t i c l e s t h a t passed the 325-mesh sieve were c l a s s i f i e d i n t o d i f f e r e n t size f r a c t i o n s by means o f a s e t t l i n g t e s t in 1 4 -i n .- h i g h glass c y l i n d e rs .

The Lead Slag t a i l i n g s were extremely coarse and were crushed to -3 mesh before the sieve analysis t e s t was made.

Ana ly sis by X - r ay d i f f r a c t i o n

A Morelco X-ray d i f f r a c t i o n apparatus was used with the copper-target tube operating a t 50 kV and 35 mA. The X-rays generated were f i l t e r e d by means o f a nickel f i l t e r , and the re s u l ts were recorded as l i n e i n t e s i t y versus the d i f f r a c t i o n angle on a chart.

The patterns were recorded between 29 values of 10 and 80 degrees at a speed o f 1 degree 29 per minute.

The p r i n c i p l e s on which the d i f f r a c t i o n technique is based

are well known ( 7 a 8). Bragg's law (nA = 2dsin9) gives a r e la t i o n s h i p between the wavelength A o f the X-rays, the d i f f r a c t i o n angle 9, and the i n t e r p l a n a r distance d. Thus each compound has i t s own

c h a r a c t e r i s t i c peaks on a recorded pa tte rn .

T - 1 1 5 1 12

Chemical analysis by X-ray fluorescence

A floreleo X-ray fluorescence apparatus with the copper-target tube operating at 40 kV and 30 mA was used f o r q u a l i t a t i v e a n a ly s is , and also f o r q u a n t i t a t i v e analysis of s i l i c o n and ti ta n i u m .

The method is as follows ( 9 ) : A high capacity e x c i t e r tube i r r a d i a t e s the unknown sample, removing electrons from the L- and K-levels and thus causing the various types o f atoms in the sample to emit t h e i r c h a r a c t e r i s t i c r a d i a t i o n s . These c h a r a c t e r i s t i c X-rays are then analyzed by means o f an analyzer c ry s ta l separating them i n t o t h e i r respective sin 9 values according to Bragg’ s law, n A = 2dsin9. Since each element has i t s own c h a r a c t e r i s t i c ra d i a ti o n an i d e n t i f i c a t i o n can r e a d i l y be made on a q u a l i t a t i v e basis.

For each t a i l i n g sample, two complete patterns were taken between 5 and 110 degrees o f 29, recording l i n e i n t e s i t y versus angle 29.

One pattern o f each t a i l i n g was taken at standard atmospheric pressure, using a l i t h i u m f l u o r i d e cr y s ta l and a s c i n t i l l a t i o n counter. This allowed the detection o f the elements above t i t a n i u m in the p e ri o d ic t a b l e , present in the sample. Another pattern was taken with the system under vacuum and with argon f l u s h i n g through, using an A. D. P.

analyzer c ry s ta l and a gas flow counter. This allowed the detection

T - 1 1 5 1 13

o f the elements between sodium and vanadium o f the p e r i o d ic t a b l e , present in the sample.

The technique was also used to obtain a q u a n t i t a t i v e analysis f o r s i l i c o n and t i t a n i u m . Standards were used with compositions s l i g h t l y lower and higher in s i l i c o n and tianium than the unknown sample,- and with a matrix s i m i l a r to the sample mat rix . The l i n e i n t e n s i t y was measured at a f i x e d angle o f 20 f o r standards and samples,

both f o r s i l i c o n and tit a n iu m . The amount o f unknown in the samples was determined by l i n e a r i n t e r p o l a t i o n . The s e n s i t i v i t y o f the

apparatus used was not very high f o r the determination o f s i l i c o n ; the re s u l ts f o r s i l i c o n analysis need to be considered as ± 2 % s i l i c o n .

Chemical analysis by atonic absorption spectrophotometry

A Techtron AA-4 atomic absorption spectrophotometry u n i t was used f o r the q u a n t i t a t i v e analysis o f i r o n , calcium, magnesium, sodium, potassium, aluminum, s i l v e r , and gold.

With t h i s technique the element which has to be determined may

be a major component or a " t r a c e " . In t h i s instance " tr a c e " metal

concentration is in the order o f one part per m i l l i o n (1 pom).

r —1 151 14

Some elements can be determined at levels below t h i s , e. g. 0.003 ppm z i n c , - but there are others which are d i f f i c u l t to determine even at the 10 ppm lev^el, e. g. vanadium (9 ).

With the present commercially av a ila bl e equipment the sample should be a l i q u i d . For s o li d s and gas samples conversion to a l i q u i d is required; the ease o f t h i s step depends on the sample under consideration. The method used in t h i s study to convert the s o l i d samples i n t o l i q u i d s is given in a fo l l o w i n g paragraph under

the he ad ing , Preparation c f samples f o r atomic absorption spect r o p h o tometry.

The basis f o r the atomic absorption analyzing method is as follows (10, 11, 12): The element being analyzed is atomized in a flame.

The atoms s tr o n g l y absorb ra d i a n t energy at t h e i r resonance frequencies.

Measurement o f how much energy i s absorbed ind icates how much o f the metal was in the sample. The process i s the reverse o f emission

spectrophotometry as can be seen from Figure 1 (10). Atomic absorption spectrophotometry looks at unexcited atoms; emission spectrophotometry detects energies from excited atoms re tu rn in g to the ground s ta t e .

Because o f the nature of the procedure, there are c er ta in advantages inherent in t h i s method:

1. I t is very s e n s i t i v e . Because of the intensive absorption at the

resonance wavelength, determinations at the ppm level can be done

e a s i l y f o r most elements.

T - 1151 15

Figure 1: The emission and absorption processes.

excited state o r b i t

+ h V

ground state o r b i t

Emission Absorption

2. I t is r e l a t i v e l y free from inte rferences by other elements.

Because the wavelength band absorbed by a p a r t i c u l a r element

i s so narrow, other elements w i l l not absorb even though they

are in the l i g h t path. Unfortunately the element i t s e l f usually

emits at the i d e n t i c a l wavelength at which i t absorbs. However,

T-1151 16

t h i s side e f f e c t has been overcome by modulating the-.equipment.

3. I t is very v e r s a t i l e . As of today about f i f t y metals can be determined by t h i s method. The concentration level o f components which can be d i r e c t l y analyzed can be varied simply by.changing

to a d i f f e r e n t absorption wavelength, or by changing the length o f the absorption o p ti c a l path. This can be seen from the Beer-Lambert law (13):

log I = log I

- K 1c

in which I

= i n i t i a l i n t e s i t y o f the beam o f r a d i a t i o n , I = reduced i n t e s i t y ,

K = e x t i n c t i o n c o e f f i c i e n t o f the vapor at wavelength ,

1 = length o f the absorbing medium, and c = concentration o f analyte.

Some o f the inherent d i f f i c u l t i e s o f the method which have not been overcome as y e t are l i s t e d below:

1. Elements must be determined one at a time.

2. Only l i q u i d samples can be analyzed by the pre sen tly av a ila bl e

equipment. Without doubt the fut ure w i l l provide us wi th the

f a c i l i t y o f atomizing s o li d s d i r e c t l y (14).

T - 1151 17

3. Cations often cause i n te rfe re nc e by c o n t r o l l i n g the rate o f reduction o f molecules to atoms.

4o About f i f t y percent o f the known elements cannot ye t be analyzed by t h i s method.

The determination of the unknown concentration o f a ce rt ai n element in an aqueous s o l u ti o n was done as fo l l o w s : The samples

were d i l u t e d so that the concentration of the analyte was in a d e f i n i t e range. This concentration range was 1 to 20 ppm f o r the elements

i r o n * calcium# magnesium, sodium, and potassium, 50 to 300 ppm f o r aluminum, and 0.05 to 1 ppm f o r s i l v e r and gold. Standards were prepared f o r each element covering the appropriate concentration range.

In the case of aluminum, chemical i n te rf er en ce by sodium was observed. To overcome t h i s problem 1000 ppm of sodium was added to the standards and samples, ' e s t a b l i s h i n g in t h i s way the same amount o f int e rf e r e n ce f o r standards and samples.

The atomic absorption u n i t used in t h i s study i nd ica tes percent transmittance (T) or absorbance (A) d i r e c t l y , where A = log 1/T.

Absorbance was p l o tt e d versus concentration. A c a l i b r a t i o n curve which i s t y p i c a l f o r i r o n , calcium, magnesium, s i l v e r , and gold

is shown in Figure 2. For s i l v e r and gold, only the section o f the

curve below 5 ppm should be considered.

I - 1 151 18

Figure 2: Typical c a l i b r a t i o n curve f o r i r o n , calcium, magnesium, s i l v e r , and gold.

absorbance

4

2

0

concentration - ppm

A t y p i c a l c a l i b r a t i o n curve f o r aluminum is represented in Figure 3. Mote t h a t the Seer-Lambert law is not obeyed at these high, concentrations.

In the case o f sodium and potassium, a d e f i n i t e i n te rf e r e n c e

was observed which was p r i m a r i l y not chemical; a l l kinds o f elements

were added to standards and samples to t e s t t h i s .

T -1151 ₁₉

Figure 3: Typical c a l i b r a t i o n curve f o r aluminum.

0.4

0 . 2

0 . 0

300 400

0 100 200

X3*

concentration - ppm

For the determination o f sodium and potassium the so- ca ll ed method o f additions or autostandardization method was used (13).

In t h i s technique, increasing amounts of the analyte i t s e l f are

added to the unknown sample, being careful to e s ta b l i s h the same

d i l u t i o n volume f o r a l l the f i n a l s o l u ti o n s . A p l o t o f absorbance

against unknown concentration X, X + 1 analyte u n i t , X + 2 analyte

T - 1 1 5 1 20

u n i t s 9 etc, , w i l l e s ta b l i s h an absorbance slope. In t e r s e c ti o n of t h i s curve with the negative po rti on o f the_concentration co-ordinate w i l l i n d ic a te the concentration o f analyte in X. See example in

Figure 4.

Figure 4: The autostandardization method.

0 . 4 - absorbance

, ⁰ . ² -

The unknown sample /

/ contains 3.2 ppm analyte.

0 . 0

---,---:---

p.

analyte added - ppm

T - 1 1 5 1 2 1

For the determination of i r o n , sodium, potassium, s i l v e r , and gold, the so lu tio ns were atomized in a ir - a c e t y le n e flame. Typical gas pressures were 2.5 psi acetylene and 15 psi a i r . The a i r- ac et y le ne flame temperature averages 2300 C (13).

Since calcium, magnesium, and aluminum form r e f r a c t o r y oxides, atomization of these elements at 2300 C is ra th e r poor. Yherefore, f o r the determination o f calcium, magnesium, and aluminum, the sol utions were atomized in an ace tylen e- nitr ous oxide flame. Typical gas pressures were 9 psi acetylene and 16 psi n i t r o u s oxide. The acet yl ene -ni tr ous

oxide flame temperature averages 2955 C (13).

P re p a ra ti on of l i q u i d samples f o r atomic absorption spectrophotometry

The fo l l o w i n g procedure was used f o r the preparation o f samples

used f o r the determination o f i r o n , calcium, magnesium, sodium, potassium, aluminum, s i l v e r and gold by atomic, absorption spectrophotometry; 500 mg were weighed in a platinum c r u c ib l e . The c ru c ib le had a capacity o f

25 ml. Five drops of p e r c h l o r i c acid and ten to twelve ml o f h y d r o f l u o r i c acid ware added. The mixture was then heated to dryness on a hot p la te . Ten ml o f p e r c h l o r i c acid were then added and the mixture was heated

f o r ten minutes,. The c r u c ib l e was allowed to cool down and the content

T - 1 1 5 1

of the c ru c ib l e was placed in a 400-ml beaker and about 200 ml d i s t i l l e d water added. The aqueous, s l i g h t l y acid, s o l u t i o n was the -allowed to b o i l f o r f i v e minutes. The eventual residue was f i l t e r e d o f f and fused with potassium pyrosulfate and added to the main s o l u t i o n .

Determination o f th e i g n i t i o n l o s s of the t a i l i n g samples

The samples were powdered and dried overnight at 110 C.

Then 200 g of each t a i l i n g sample were weighed in a porcelain

c ru c ib l e and calcined in an e l e c t r i c furnace at 1000 C f o r one hour.

The weight of the calcined sample was then determined. The i g n i t i o n loss was determined from the fo l l o w i n g expression:

dry weight - calcined weight

% I g n i t i o n loss = ■ = --- — --- x 100.0

dry weight

T - 1 1 5 1 23

Density measurements

The density o f the t a i l i n g s was determined by pouring a known weight o f material in a 100-ml glass c y l i n d e r and then a reading was taken o f the volume i t occupied.

The packed density was determined by pouring a known weight o f material in a 100-ml glass c y l i n d e r and determining the volume i t occupied a f t e r shaking the glass f o r f i v e minutes.

Prop a r a ti on o f t e s t bars

The specimens in which calcium hydroxide was used as the bonding agent were prepared by thoroughly mixing, u t i l i z i n g a mortar and a p e s t l e , the proper amounts o f the desired powders with enough

moisture to hold the specimens together a f t e r forming. The specimens were formed by pressing- in a rectang ular brass die using a Carver Laboratory h yd ra u lic press having a 20,000-lbs capacity. The pressure exerted by the Carver press on the specimens was 15,000 lbs. The

formed bars were 5 x 1 x 0.4 i n . in s i z e , which resulted in a

forming pressure o f 2,500 psi.

T-1151 24

The specimens in which Penep.rime was the bonding agent were prepared by thoroughly mixing the proper amounts of t a i l i n g and Peneprime l i q u i d . The specimens were formed by pressing in a rectangular brass die using hand pressure or a Carver Laboratory hy d ra u l ic press, using various pressures up to 6,000 lbs maximum, which re sul ted in a maximum forming pressure of 1,000 ps i.

Aging* o f t e s t bars

The specimens with calcium hydroxide as the bonding agent were aged at d i f f e r e n t temperatures f o r d i f f e r e n t times. Aging at room temperature and atmospheric pressure was done in the a i r . Aging at 100 C in steam, and aging at 125 C in steam were done in an e l e c t r i c a l l y - h e a t e d autoclave. The autoclave was manufactured by Barnstead S t i l l and S t e r i l i z e r Company, and was of the type with hinged door and double w a l l .

The specimens w ith Peneprime as the bonding agent were aged

a t . 110 C in a dryer f o r d i f f e r e n t time periods. A f t e r 10 days o f

aging the strength did not.incre ase any more; the refore an aging

time o f 10 days was choosen f o r a l l t e s t s .

T - 1 1 5 1 25

Strength determinations

The normal method o f measuring the strength of a ceramic material is by e i t h e r a crushing t e s t or a modified t e n s i l e t e s t which measures the modulus of rup ture. Of the two test s the modulus

of rupture t e s t is more acceptable because i t gives more accurate data.

The determination of the modulus of rupture o f the specimens was done according to the method described f o r t e s t i n g f i r e c l a y - base cashable r e f r a c t o r i e s a f t e r f i r i n g (14). In p r a c ti c e the t e s t consists of supporting the sample on two k n i fe edges and applying a load on another k n i f e edge at the center of the bar u n t i l

f r a c tu r e occurs. In t h i s study the sample was supported by two 1 / 8 - i n . diameter hardened-steel rods and the load was applied on a s i m i l a r - size rod. The modulus o f rupture of c-ach specimen was calculated according to the f o l l o w i n g expression:

3 P L

where M = modulus of rupture in p s i ,

P = load in lbs at which the specimen f a i l e d ,

T-1151 26

L = distance in i n . between the cen ter lin es o f the lower bearing edges,

b = width of the specimen in i n . , and d = depth o f the specimen in i n .

The load was applied at a speed o f 0.11 i n . per min' and was held the same in every t e s t . This is necessary since the rate o f a p p l i c a t i o n o f load has a very decided e f f e c t on the r e s u l t s . The modulus o f rupture values increase f o r increasing rates of

load a p p l i c a t i o n .

The widthand the depth of the specimens was measured by means o f a micrometer near the fr a ct ur e d surface.

The t e s t i n g machine used f o r t h i s work was a Baldwin-Emery SR-4 t e s t i n g machine, model FGT,

Determination o f the water o f absorption

The water of absorption was determined f o r each specimen wi th Peneprime as the bonding agent.

The method was as fo l l o w s : The dry weight o f the sample was

determined. Then the sample was bo ile d in water f o r one hour and

T - 1 1 5 1 27

the wet weight was determined. The water of absorption was calculated from the fo l l o w i n g expression:

wet weight - dry weight

% Hater of absorption = --- :--- x 100 dry weight

S o l u b i l i t y measurements by means o f o p t i c al emissionspectroscopy

S i l i c a in the form o f t a i l i n g s or in the form of po tters f l i n t was added to saturated so lu ti on s of calcium hydroxide in water, and to saturated so lu ti o n s of magnesium hydroxide in water. The mixtures were brought in contact f o r one hour at d i f f e r e n t

temperatures. The d i f f e r e n t reaction conditions used were the f o l l o w i n g :

1. At. 25 C and atmospheric pressure, and s t i r r e d magnetically.

2. At b o i l i n g temperature o f the s o l u ti o n (about 100 C) and atmospheric pressure, using a r e f l u x condensor.

3. At 125 C and 19.4 psi overpressure, in an autoclave.

The solu tion s were then f i l t e r e d and the f i l t r a t e was heated

to dryness. The residue o f the drying operation was then analyzed

f o r s i l i c o n by means o f o p ti c a l emission spectroscopy.

T - 1 1 5 1 28

I t is well known t h a t the s o l u b i l i t y o f calcium, hydroxide and o f magnesium hydroxide in water changes with temperature (16).

However our ob jec t is not to measure absolute q u a n t i t i e s o f s i l i c o n going i n t o a c e r ta in volume o f saturated s o l u t i o n , but to measure the q u a n t it y o f s i l i c o n going i n t o s o l u t i o n f o r a ce rt ai n amount o f calcium hydroxide or magnesium hydroxide in s o l u t i o n .

The technique of o p t i c a l emission spectroscopy is as fo l l o w s : The sample nixed with an equal amount o f graphite powder is excited

in a D. C-. arc, and a c h a r a c t e r i s t i c spectrum o f a l l the elements present in the sample is obtained on a photographic p l a te . An o p t i c a l

densitometer is used to i d e n t i f y the li n e s in the spectra and to

determine t h e i r r e l a t i v e i n t e n s i t y . In t h i s way a q u a l i t a t i v e

analysis f o r s i l i c o n could be establ ishe d.

T-1151 29

EXPERIMENTAL RESULTS AMD DISCUSSION

Moisture content o f the t a i l i n o s

The values obtained f o r the moisture content o f the d i f f e r e n t t a i l i n g s are represented in Table 2.

The v a r i a t i o n in moisture content is due to the d i f f e r e n t con stituents in the t a i l i n g s , and e s p e c i a l l y to the degree o f dryness o f the t a i l i n g s as they came i n .

Results of sieve analysis test s of t a i l i n g s

The grain size d i s t r i b u t i o n s obtained f o r the d i f f e r e n t t a i l i n g s are represented in Table 3,

Several t a i l i n g s were not su ite d very well f o r a s e t t l i n g t e s t .

Note the dif fe re n ce in grain size d i s t r i b u t i o n o f the two Climax

t a i 1i n g s .

t - 1 1 5 1

Table 2:

30

l o i s t u r e ' content o f the t a i l i n g s

T a i l i n g Percent moisture

Old Climax 2.56

Young Climax 0.00

N a tu r i ta 0.00

Durango 4.80

Idaho Springs i 4.56

Ouray 11.00

S i lv e r t o n 5.33

Lead Slag 0.00

Sawach 3.31

Lower Denaro 6.05

Iron Mask 2.24

L i t t l e Jonny 2.82

El Capitan 3.75

F. T. E. 4.42

T - 1 1 5 1

T a b l e 3: S i e v e a n a l y s i s o f

t a i l i n g s ( p e r c e n t a g e s ) .

8 mesh 8 + 1 0 mesh 10 + 14 mesh 14 + 20 mesh 20 + 28 mesh 28 + 35 mesh 35 + 48 mesh 48 + 55 rnesh 65 + 100 mesh

100 + 150 mesh 150 + 200 mesh 200 + 325 mesh 325 mesh + 10 w.

10 M + 5 M 5 M + 2 2 M + 1 M 1 M

X

O

“O

o

0. 0 0 0 . 0 0

0.15 1.02 5.03 5.53 32.67 19.91 13.99 8.23 5.14 3.27 4.30 0.60 0 . 2 0 0 . 0 0 0 . 0 0

<TJ

o

Cn

C

Z3

o

0 . 0 0 0 . 0 0

0. 00 0.03 0.67 2.87 7.57 10.23 11.66

10.00

■8 . 6 6

6.74

43.98

i/)

s- cu

to

o

_ c

ra

*o

28.34 2.46 2.95 3.79 4.13 4.33 4.77 3.77 3.91 3.15 3..10 2 . 6 6 7.65 24.77 0 . 2 0 0 . 0 0 0 . 0 0

rC +J fO

1.27 0.10 0.50 1.86 2.57 3.76 9.60 16.32 24.98 17.06 10.53 5.24 4.60 1.29 0.30 0.09 0 .0 0

o

c:

f u

s- a rs

0.25 0.54 1.61 2.87 2 . 8 6

4.25 7.99 16.08 22.28 15.63 7.88 6.41 6.08 3.78 1.29 0.18 0 . 0 0

cn ro

I——

to

-a

iT3

CJ

12.70 17.50 15.40 10.57 8 .6 6

7.70 6.63 4.83 3.83 2.93 2.92 5.68 0.50 0 . 2 0 0 . 0 0 0. 0 0

rc

i-

o

49.50

1.61

2,55

3.00

2.67

2.70

2.77

4.19

6.54

5.51

5.17

4.37

4.46

3.34

1.57

0.03

0. 0 0

T - 1 1 5 1 32

T a b l e 3 ( c o n t i n u e d ) : S i e v e a n a l y s i s o f t h e t a i l i n g s ( p e r c e n t a g e s ) .

Q

4->

G .

+->

+->

O I—

Ll_

33.70 0.26 76.51

43.00 51.05 47.67

+ 8 mesh 52.30

3.91 1.71

2.69 2.90 4.13 3.44

0.77 4.31 3.79 2.16 4.33

4.25 6.23

5.77 2.29 2.63

3.73 6.81 4.71

14 + 20 mesh

6.09 4.89

4.49 3.78 1.65

- 2 0 + 2 8 mesh 2.38 4.88

11.17 4.97

3.95 3.36 1.40

2 8 + 3 5 mesh 4.42

5.23

1.56 3.80 3.21 3.41 0.58

35 + 48 mash

13.27 2.75 1.12

1.45 3.36

- 4 8 + 6 5 mesh

14.11 3.17 1.38 5.41

2. 21 2.92 1.22

- 65 + 100 mesh

9.98

2.47 2.65

100 + 150 mesh 1.14

2.53 0.41

0.48 0.06

0.74 150 + 200 mesh 1.10

14.94

2.45 5.58

4.23 6.19

3'. 45 2.10

- 200 + 325 mesh

10.52 10.00

325 mesh + 10 R

12.11 1.30 10 K + 5 R

7.64 14.85 0.26 12.14

18.71 1.05

6.70 0.54 0.05

o.oo-

0 . 0 0

1M

T - 1 1 5 1 33

Results o f X-ray d i f f r a c t i o n analysis

X-ray d i f f r a c t i o n patterns were run on a l l the t a i l i n g samples.

The fo l l o w i n g compounds were found to be present in detectable amount in a l l the samples except the Lead Slag:

1. Alpha quartz (SiOg),

2. Muscovite, na tural 3T~type, (K,Na) (A I, Mg, Fe)g (Si^ j AI^ Q)

■(OH) £ » ' and

3. Orthoclase ( F e l d s p a r ) K ’ (A1, Fe) Si^Og.

Since t h i s analysis is q u a l i t a t i v e ra th e r than q u a n t i t a t i v e , i t is impossible to state the amount o f these compounds present in the sample. However i t was c le a r from the obtained patterns t h a t alpha quartz was the most abundant component.

The d i f f r a c t i o n pattern o f Lead Slag did not show any decided peak, which in d ic a te d t h a t i t was p r i m a r i l y an amorphous glass.

Chemical analysis r e s u l t s -

The r e s u l t s o f the a u a n t i t a t i v e - a n a l y s i s of the t a i l i n g s are

represented i n.T abl e 4.

T - 1 1 5 1 34

Table 4: Chemical analysis o f the t a i l i n g s .

X

CO CD X

rg E

*r~

<_>

E

•r—

r—■

O O'.

c

•r—

S- o.

CO o

rC -M si

o O ' c

ra CO

“O

~ o r —■

o

3

o

> -

jcz.

<v>

- a V—(

- j +J- fO

i - 13 Q

raa

* w

%.

O

o

c/

/o

t

Si 0^ 84.15 78.25 69.50 85.74 83.05 45.01 72.09

O f

io a i

2

3 7.22 11.01 10.11 6.16 7.10 6.51 10.40

% FeO 1.23 1.82 5.77 1.03 1.54 30.90 5.79

c /iOn

° 2 0.14 0.18 0.61 0.16 0.27 0.81 0.47

% CaO 0.22 0.35 0.11 1.00 1.08 12.84 0.28

% Mg O' 0.39 0 S80 0.94 1.17 1.08 1.60 .1.26

%

K? 0 2.97 3.22 2.13 0.75 0.95 0.90 2.18

Of

I Na20 0.13 0.21 1.23 1.09 1.42 0.74 0.54

c f

io

Ag

< .003

.002

.002 4. .002 .002 < .002

c!

io

Au

.002 < .002 < .002 < .002 < .002 0.005 .002

of

io

Ign. loss 1.23 1.85 8.74 0.91 1.71 0.00 6.01

<Y

/o

t o t a l 97.68 97.71 99.15 98.01 98.21 99.31 •99.02

T - 1 1 5 1 35

T a b l e 4 ( c o n t i n u e d ) : C h em i c a l a n a l y s i s o f t h e t a i l i n g s .

c o +->

s -

sz

o i-

n3 C

Qi

O r

in r3

c

ra

+ J

• r “ C L IO

> >

c c o

o

• U J

QJ

u fO

3: ^o

o

c o

C_) 4->

4-> 1—-

•r—

OO

LTi

of

Io

Si 02 63.10 79.09 71.75 78.15 69.26 58.00 68.75

ot

Io

A12°3 17.76 10.33 13.56 4.26 15.61 7.93 7.41

% FeO 5.69 2.80 3.64 5.48 4.62 12.77 10.24

Of

Ti°2 0.82 0.27 0.30 0.34 0.26 0.40 0.36

% ^{CaO 0.13 0.06 0.13 0.10 0.13 3.58 1.96}

%

0.38 0.64 0.85 0.12 0.70 3.40 1.96

%

2.61 2.27 1.90 0.57 1.73 0,90 1.02

°/

Na„0 0.38 0.09 0.08 . 0.04 0.09 0.09 0.10

% Ag 0.003 0.011 0.015 0.010

.002 0.002

.002

c/

Io A u <

.002

.002 < .002 0.003

.002 0.004 .002

% Ign. loss 7.73 3.64 5.81 9.41 5.96 12.80 6.17

% Total 98.60 99.19 98.02 98.47 98.36 99.87 97.97

T - 1 1 5 1 36

The X-ray fluorescence method was used f o r the determ ination o f s i l i c o n and tita n iu m . A ll o th e r elements were determined by atomic absorption spectrophotometry. Except f o r s i l v e r and gold the r e s u lts were expressed in percentage o f the oxide.

The values obtained f o r s i l v e r and gold cannot be taken as • t r u l y re p re s e n ta tiv e f o r the content o f these elements in the t a i l i n g , p i l e s . This is due to the sampling method.

In order to check the a n a ly tic a l methods used in t h is study, a clay named "Johnson Red.Shale" was analyzed by wet chemical an alysis at the Wood L a b o ra to rie s , and also in t h is work by the methods c ite d above. The re s u lts o f both analyses are represented in Table 5.

Re s u 1 ts from s o 1 ub i 1 i tv me as u re men ts

A q u a n t it a t iv e analysis f o r s i l i c o n could not be obtained by

o p tic a l emission spectroscopy, because o f the very small amount o f

s i l i c o n present in the samples. However most im portant are the

q u a l i t a t i v e r e s u lt s , I t was found t h a t the higher the temperature

o f re a c tio n , the more s i l i c o n went i n t o s o lu tio n f o r a c e rta in

amount o f calcium hydroxide or magnesium hydroxide in the s o lu t io n .

T - 1 1 5 1 37

Table 5: Comparison between wet chemical analysis by Wood Laboratories and the a u th o r's a n a ly s is .

Wood This study

% SiOg 42.40 43.70

% A1„CL

L 3 15.37 15.22

. ’% FeO 3.60 3.61

% T i0 2 0.41 0.45

% CaO 11.95 12.00

% MgO 1.78 1.70

%

2

1.18 1.31

% Na2Q 0.89 0.85

% I g n it io n loss 19.33 19.46

% Total 97.80 98.30

Since the formation o f hydrated calcium s i l i c a t e s is l i k e l y

to take place in the l i q u i d s ta te (see above), the reactants have

to go in to s o lu tio n before the re a c tio n can take place.

T - 1 1 5 1 38

The r e s u lts thus in d ic a te d th a t a la rg e r amount o f hydrated calcium s i l i c a t e s , and hence a hig he r strength could be expected f o r the t e s t bars, cured at the higher temperature.

Strength re s u lts f o r t e s t specimens w ith calcium hydroxide as bonding agent

Calcium hydroxide was selected as bonding agent. Magnesiurn hydroxide was not considered because i t is r e l a t i v e l y expensive, and also because the water s o l u b i l i t y o f magnesium hydroxide is much sm alle r than th a t o f calcium hydroxide. However i t is believed t h a t s i m i l a r re s u lts could be obtained using magnesium hydroxide.

The compositions used f o r the t e s t bars were as fo llo w s :

Series C: 100 g Young Climax t a i l i n g 35 g calcium hydroxide 25 ml water

Series P: 100 g Young Climax t a i l i n g

35 g calcium hydroxide

10 g Portland cement

25 ml water

T - 1 1 5 1

The specimens a f t e r forming had no measurable stre ngth* The specimens showed a considerable increase in strength a f t e r various a i r curing tim es, and also a f t e r various steam curin g treatment times.

The stre ngth o f the a ir-c u re d specimens as a fu n c tio n o f curing time is given in Table 5 and represented in Figure 5. The strength o f the specimens cured in 100 C steam as a fu n c tio n o f curing time is given in Table 7 and shown in Figure 6. The’ stre ng th o f the

specimens cured in 125 C steam as a fu n c tio n o f curing time is given in Table 8 and shown in Figure 7*

The values f o r the modulus o f rupture given in Tables 6, 7, and 8, and represented in fig u re s 5, 6, and 7 are average values c a lc u la te d from 15 d i f f e r e n t te s t s .

I t is c le a r from Figures 5 , 6 , and 7 th a t steam curing is a much f a s t e r strengthening method than a i r c u rin g . A comparison o f Figures 6 and 7 also shows th a t the hig her the steam temperature the f a s t e r the strengthening takes place. This is in p e rfe c t agreement w ith the r e s u lts from the s o l u b i l i t y measurements, confirm ing th a t the strengthening in a steam atmosphere p r im a r ily occurs w ith the formation o f hydrated calcium s i l i c a t e s . Hydrated calcium s i l i c a t e s could not be detected in the steam-cured specimens by X-ray

d i f f r a c t i o n an alysis because these compounds are mostly amorphous.

However Hall (5) detected them by e le c tro n microscopy stu d ie s .

T - 1151 40

In the a ir-c u re d specimens the presence o f calcium carbonate was detected by X-ray d i f f r a c t i o n analysis o f the bulk o f the sample.

By powdering the samples the calcium carbonate peaks disappeared from the p a tte rn almost com pletely. This in d ic a te s th a t the carbonate was probably being formed at the surface o f the s o lid hydrate i n ­

voids between p a r t i c l e s . ;

More calcium carbonate was found at the surface o f the specimens than on the in s id e which was s o f t and chalky compared to the

r e l a t i v e l y hard surface. .

From a comparison o f the modulus o f rupture values f o r the longest curing times in the three cases, i t can be estimated th a t i f longer curing times were allowed, the maximum strengths obtained would be o f the same magnitude f o r a ir-c u re d specimens and f o r steam-cured specimens. This confirms th a t both 1ow-temperature cementitious re a c tio n s , form ation o f calcium carbonate and formation o f hydrated calcium s i l i c a t e s r e s u l t in the same amount o f

s tre n gth e n in g.

Also i t can be seen from Figures 5, 6, and 7 t h a t the e f f e c t

on. the stre n gth o f adding Portland cement to the specimen composition

is ra th e r s m a ll, and in the order o f 0 to 5 %.

T—1151

Table 6: Modulus o f rupture ( in nsi ) o f a i r - cured specimens versus a i r - curing time.

A i r curing time

3 days 1 week 2 weeks 3 weeks 4 weeks 5 weeks 6 weeks 7 weeks

Series C

180 331 512 565 591 605 618 620

Series P

185 336 515 571 595 606 620 624

Figure 5: Modulus o f rupture o f a i r - cured specimens, versus a i r - curing time.

700

l/!

CL

,509 _

CJ S~

n 4->

CL Z3

300

<A

a a

* o o

100

serie s P serie s C

4 5 6

Time a i r cured - weeks

M o d u lu s of ru p tu re - p s i

T - 1151 42

Table 7: Modulus o f Rupture ( in psi ) o f 100 C - steam - cured specimens, versus steam - curing time.

Steam - curing time Series C Series P

1 hour 176 179

2 hours 305 303

4 hours 426 437

8 hours 549 561

12 hours 632 647

16 hours 668 679

Figure 6: Modulus o f rupture o f 100 C - steam - cured specimens, versus steam - curing time.

700

500

series P 300 1

series C

100

1 2 4 8 12 16

Time s t e a m c u r e d - h o u r s

T - 1 1 5 1 43

Table 8: Modulus o f Rupture ( in psi ) o f 125 C - steam - cured specimens, versus steam - curing time.

Steam - curin g time Series C Series P

1 hour 2 hours 4 hours 8 hours 12 hours

242 387 559 705 745

245 392 570 725 749

Figure 7: Modulus o f rupture o f 125 C versus steam - curing time.

700 -

steam - cured specimens,

tn

O-

CL>

^ 500

C X

£<

<+-

o

in

- j

~a

300 A

100

series P series C

-I— 12

Time s t e a m c u r e d - h o u r s

T - 1151 44

These ta i lin g s , except the lead s la g , could thus w ell be used f o r the production o f sand-1ime b r ic k , economical fa c to rs not taken i n t o co n s id e ra tio n .

Mo attempt was made in t h is study to optimize the amount o f calcium hydroxide used.

Results from d e nsity measurements

Density measurements were made f o r the fo llo w in g t a i l i n g samples:

Old Climax, Young Climax, N a t u r it a , and Durango. The re s u lts f o r the unpacked d e nsity and the packed de nsity are given in Table 9.

Table 9: Unpacked d e n sity and packed denasity f o r fo u r t a i l i n g s .

---

- —

f a i l i n g

.

Unpacked de nsity (o /c c )

Packed d e nsity (g /c c )

Old Climax 1.36 1.61

Young Climax 1.25 1.54

N a tu rita 1.44 1.62

Durango . 1.40 1.59

T-1151. 45

Because o f i t s hiqh packed d e n s ity , the N a tu rita t a i l i n g was then choosen f o r a more d e ta ile d study of the packed d e n s ity .

The N a tu rita t a i l i n g was d iv id e d in t o the fo llo w in g grain size f r a c t i o n s :

a = -4 mesh + 48 mesh b = - 43 mesh + 65 mesh c = - 65 me'sh + 100 mesh

d = - 100 mesh + 200 mesh, and e = - 200 mesh.

By making combinations in 20 % steps w ith these f i v e f r a c t i o n s , a maximum packed de nsity o f 1,71 g/cc was found f o r the fo llo w in g compositi on:

80 % o f g rain size f r a c t io n a, and 20 % o f grain s iz e f r a c t io n e.

Complete re s u lts f o r the packed de n sity are given in Appendix A.

Strength re s u lts f o r t e s t specimens w ith Peneprime as bonding agent

The composition o f the mixture used f o r the t e s t bars was:

80 % N a tu r ita a + 20 % N a tu rita e, since t h is composition had shown