DISTRIBUTION OF GIBBSITE AND KAOUNITE WITH DEPTH IN A ... · of bauxite (gibbsite) designated as...
Transcript of DISTRIBUTION OF GIBBSITE AND KAOUNITE WITH DEPTH IN A ... · of bauxite (gibbsite) designated as...
TECHNICAL PROGRESS REPORT 125 SEPTEMBER 1960
DISTRIBUTION OF GIBBSITE AND KAOUNITE
WITH DEPTH IN A GIBBSITIC SOIL ON KAUAI
W. E. Holmes,
Makoto Takahashi,
and
G. Donald Sherman
HAWAII AGRICULTURAL EXPERIMENT STATION, UNIVERSITY OF HAWAII
TECHNICAL PROGRESS REPORT 125 SEPTEMBER 1960
HAWAII AGRICULTURAL EXPERIMENT STATION, UNIVERSITY OF HAWAII
Honolulu, Hawaii
DISTRIBUTION OF GIBBSITE AND KAOLINITE
WITH DEPTH IN A GIBBSITIC SOIL ON KAUAI
w. E. Holmes, * Makoto Takahas.h.i,t and G. Donald Sherman+
Gibbsitic soils of Hawaii have been described by Shennan (2). Thesesoil s are located on all major islands, and they have received serious consideration by mining companies as possible sources of bauxite. Becausesuch soils may eventually be mined, the University of Hawaii was authori zed by the 1957 Terri tori al Legislature to conduct experim-ents in the revegetation of a simulated stripmined area. An area was selected in theWailua Game Refuge on Kauai as an experimental area. In order to evaluatean appropriate depth at which to termin ate the simulated mining operations,analytical data were needed. These data were obtained from borings takenfrom the experimental area prior to starting the excavation. The purpose ofthis report is to describe the chemical and mineral composition oIbhebauxite deposits on the island of Kauai.
EXPERIMENTAL PROCEDURES
Sampling: Thirteen borings were made over the experimental area. Theborings were made after 1.0 to 1.5 feet of topsoil had been removed. A 3inch diameter, hand-operated soil auger was used. Samples were taken at 1-
* Formerly Assistant Soil Scientist at the Hawaii Agricultural ExperimentStation and Assistant Professor of Agriculture, University of Hawaii.
t Assistant Agronomist at the Hawaii Agricultural Experiment Station.
:j: Senior Soil Scientist, Hawaii Agricultural Experiment Station; Head,Department of Agronomy and Soil Science, College of Tropical Agriculture; and Senior Professor 0 f Agriculture, University of H.awaii.
3
foot intervals to depths. ranging from 15 to 20 feet. A single boring wastaken to a depth of 35 feet, of which the last 20 feet were done after theexcavation of 14 feet. E a ch sample was placed in a plastic sack for shipment to the laboratory of the Department of Agronomy and Soil Science, 'foranalysis.
Upon arrival at the laboratory, each sample was thoroughl y mixed, anda small representative portion of the sample was obtained by, successivequarterin gs , This small sample was dried at 600C., ground to pass througha 60-mesh sieve, then placed in a labelled vial to be saved for differentialthermal analysis. The major portion of the initial moist sample was returnedto the plastic sack to be preserved for a sieving analysis.
Differential thermal analysis: A portable differential thermal apparatusdesigned for rapid anal yses was used. The procedure differed from that described by Norton (1) in that the rapid procedure made use of a fast, nonuniform heating rate. The temperature range used was from room temperature toabout 650 0 C. This range permitted observing the characteristic endothermicreactions of gibbsite and kaolinite with the apparatus employed. A sampleof bauxite (gibbsite) designated as Dana 261 was used as a referencesample for estimating the percentages of gibbsite. The reference sample forestimating the perc en tage s of kaolinite was labelled Dana 492. The originsof the gibbsite and kaolinite reference samples were, respectivel y, LittleRock, Arkansas, and the McNamee Mine in South Carolina.
Sieving analyses: These analyses were conducted to determine thedistribution of gibbsite and kaolinite with respect to size of the soil particles and agwegates. The moist samples saved after sampling for differentialthermal analyses were used. In order to have sufficient sample for sievinganalyses, the samples were composited such that each sample used forsieving represented increments of depth ranging from 3 to 6 feet.
For each si eving anal ysis a sampl e of some 500 to 600 grams of moistsoil was. used. From this, three samples ranging from 30 to 50 grams weretaken for a moisture determination. The moisture determination was necessary for making all cal culations on a dry weight basis. Prior to sieving,each sample was stirred in an aqueous suspension for 20 minutes with alaboratory stirring device. A series of sieves which included the 9-, 16-,32-, 60-, 115-, and 200-meshes per inch sizes were used, but only the dataof the 60-mesh sieve are used in this report. The material remaining on eachof these sieves was collected, dried at 1050 C., and weighed. The percentages retained on each sieve were calculated using the estimated ovendry weight of the initial moist sample. This estimate was made using theinfonnation gained from a moisture determination. Small portions of eachdried sample were prepared for differential th erm al analysis in order toobserve the distribution of gibbsite and kaolinite in each size fraction.
"
RESULTS AND DISCUSSION
Variability in distribution of gibbs ite and kaolinite: The data obtainedfrom the differential thermal analysis are presented in table 1. Although thetwo sites studied are part of the same ridge and are essentially contiguous,being separated by a narrow neck about 300 feet long, gross inspection ofthe data between the two sites indicates distinct differences in the concentration and depth of gibbsite deposits. Subsequent stripping operations indicated some differences in the ore body. Some difference was noted in thecharacter of the weathered rocks. In the East site, nodules and fragments ofgibbsite were frequently encountered over the entire area but none was foundin the West site.
Because of the apparent differences between the two sites, data wererecorded and treated separately. Data on differential thermal analyses ofaverages of five borings taken from the East site and the averages of eightborings taken from the West site are presented in table 1. Since many of thereports on bauxite research present their data in terms of alumina (AI203)instead of gibbsite, the alumina equivalent has also been included in thetable. The following conversion factor was used: 100% gibbsite = 65%alumina.
In the East site the content of gibbsite increases with increase in depthup to the 8-foot depth and thereafter there is a steady decline with someminor fluctuations. On the other hand, in the West site gibbsite content remains at relatively uniform level up to the 8-foot depth and diminishes thereafter with increase in depth. With the exception of the first foot of sampling,the East site has materially higher gibbsite content for all levels of depththan those of corresponding depths in the West si teo In nine of the foot-inter-val sampl es, those from th e East site had doubl e th e gibbsite content ascompared to the corresponding samples from the \Vest site. The differencesin gibbsite content for corresponding depths for the two sites are presentedIn table 3. -
Individual borings highly variable: Marked variations were noted between borings. The extent of variability between the different borings can bereadily seen by inspection of figure 1, in which th-e first three borings takenfrom the East site were plotted out individually. The case history of boringNo.3 is especially an interesting one. At the 6-foot depth it recorded thehighest gibbsite content of 52 percent out of a total 244 readings taken.However, from the 7-foot depth on, the content of gibbsite dropped abruptlyand none was recorded from the 12- to the 18-foot depth.
Because of the great vari ab i l ity in individual borings, for assaying anyprospective individual bauxite ore body site, a minimum of three boringsshould be taken.
5
52.5
45
315
WJ-(f) 30(D(D
(!)
~22.5zw(,)
a:: 15wQ.
~"'I
",I, ~, I, I, ,
I I, I
,r\ !/~I '{ \I !.I ,
/~ ,0'\ 'I '\ I, \ :I ! " :, \,, \,, \,,
nI \I \I \
\\ ~\ I \\ I \\ I \
\ r\ I\ I
~\\\\ p~
I3
BORING .. ,BORING #2BORING .#-3
I I6 9
DEPTH
Figure 1. Distribution pattern of gibbsite in the first three borings taken from theEast site.
Kaolinite-its distribution and relation to gibbsite: Examination of datapresented in table 1 clearly indicates that the content of kaolinite increaseswith depth. In general, kaolinite content increased very slowly for the first 8to 10 feet of depth but from 8 to 10 feet to the 18-foot depth it increasedprogressively with each increase in depth. Examination of the analyses ofgibbsite and kaolinite indicates high correlation. The precise rel ationshipbetween these two components was explored statistically by working out theregression equation. The results of the statistical analysis show a linearregression relationship between kaolinite and gibbsite.
6
TABLE 1. Tabulation of gibbsite content and percentage difference of two sites atvarying depths from 1 to 18 feet
Depth Percent gibbsite, Percent gibbsite, Di fference Percent
in feet East site West site between two increase orsites decrease in
gibbsitecontent - Eastover West site
1 15.6 18.6 - 3.0 - 10.62 23.8 20.6 + 3.2 + 15.5
3 24.8 20.0 + 4.8 + 24.0
4 33.4 25.5 + 7.9 + 31.1
5 29.8 20.2 + 9.6 + 47.3
6 37.0 18.6 + 18.4 + 98.3
7 39.4 21.0 + 18.4 + 87.6
8 29.4 14.0 + 15.4 + 102.3
9 24.6 10.7 + 13.9 + 129.1
10 30.8 13.5 + 17.3 + 127.9
11 17.8 10.3 + 7.5 + 73.4
12 17.0 10.1 + 6.9 + ss.o13 23.2 10.1 + 13.1 + 130.3
14 14.2 9.6 + 4.6 + 47.3
15 10.2 9.8 + 0.4 + 4.0
16 20.7 6.6 + 14.1 + 121.3
17 15.7 3.3 + 12.4 +254.9
18 14.0 5.3 + 8.7 + 96.3
Distribution of gibbsite and kaolinite in various size fractions: Datapresented in table 2 show the distribution of gibbsite and kaolinite in thefractions greater and less than 60-mesh in size. The data are from 4 of the13 borings made in the two excavation areas. The percentages of gibbsiteand kaolinite are weighted averages calculated from data presented in theappendix.
Within the upper 10 to 12 feet of the four borings, an average of 41 percent of the material was retained on a 60-mesh sieve. This average figuremay be somewhat high for samples from this area because of an unusuallyhigh value of 61 percent observed in hole No.6 of the West excavation site.The average of the other five borings is but 34 percent, The average gibbsite content in the greater than 60-mesh fraction was found to be 45 per cent,which compares to 25 percent observed in the unfractionated soil. Kaolinitein the greater than 6Q-mesh fraction was essentially the same as that of theunfractionated soil. An average gibbsite content of only 21 percent wasfound in the less than 60-mesh fraction, and the kaolinite content also wasnot essentially different from that of the unfractionated eoil; i.e., 2 to 3percen t,
7
T ABL E 2. Distribution of gibbsite and kaolinite in the size fractions greaterand less than 60-mesh
Dep th, feet Fraction Percentage 0 f
to tal sampl e
Percent
gibbsite
Percent
kaolinite
3 - 11
12 - 20
1 - 10
11 - 20
1 - 10
11 - 19
1 - 8
9 - 20
60 mesh60 mesh60 mesh60 mesh
60 mesh60 mesh60 mesh60 mesh
60 mesh60 mesh60 mesh60 mesh
60 mesh60 mesh60 mesh60 mesh
Hole No.1, East excavation
27672177
Hole No.4, East excavation
31662670
Hole No.5, East excavation
45552476
Hole No.6, West excavation
61365643
671843
7
3812
45
44336928
30
2084
oo
1216
6125954
oo16
oo
3230
Averages of four holes, fractions
1 - 10
10 - 20
60 mesh
60 mesh60 mesh60 mesh
41553267
45213111
2
32627
1 - 10
11 - 20
Averages of unfractionated soil
Entire soil 25
Entire soil 17
8
3
29
T ABL E 3. Che mical ana ly ses of a Kapaa si l ty clay profil e wi thin th e reclamationproj ect, Wai lua, Ka uai
Depth, inch es Si lic a (Si02), per c ent Alumina (AI203)' per cent
o - 10 6.58 29.7 610 - 15 1.85 3 1.4415 - 30 0.90 37.4430 - 69 0.69 42.3269 - 74 0.70 40.1674 - 77 0..73 4 1. 3277 - 93 0.67 42. 1693 - 103 0.72 40.40
103- 104 0.59 37.60104- 128 2. 18 29. 12128 - 130 4.27 31. 20130 - 136 5.7 1 28.48136 - 146 18. 50 29. 04146 - 150 8.85 40.48150 - 160 2 1.79 29.28160 - 170 9.0 2 45.9 2
Within the 10- to 20- foot depth, the average gibbsite content of thegreater than 60-mesh fraction was 31 percent, whi ch comp.ares to 17 percentfor the average of the unfractionated soil from th at depth. Kaolinite content,however, in the greater than 60-mesh fraction was found to be 26 percent,which is not essentiall y different from that of either the Iess than 60-meshfraction or the unfractionated soil.
Comparison of differential thermal data wi th those from chemical analy
ses. Table 3 presents data from a single sampling in the same area fromwhich samples for the differential thermal data we re obtain ed. The samplesused for the anal yses represented in ta ble 3 are not the same as th ose usedfor the differential thermal data presented in table 1, but are taken from anadjacent site. In the differential thermal data of table 1 the percentages ofkaolinite and gibbsite are, respectivel y, measures of the percentages ofsilica (Si02) and alumina (AI203). Data in table 3 are expressed as silicaand alumina. For purposes of comparison, kao i in ite is 46 percent silica and40 percent alumina.
Keeping in mind that gibbsite is but 65 percent a lumina , a comparisonof the data of table 3 with those of table 1 shows that at depths up to 10feet the differential thermal data tend to underestimate th e percentage ofalumina. This conclusion that the differential thermal data tend to underestimate the percentage of alumina appears to be justified because, withinthe top 10 feet, several of the samples of table 3 anal yzed 40 percent alumina. This corresponds to a gibbsite percentage of 60, which is higher than
9
any of the samples reported in table 1. The alumina contributed by kaoliniteis ne gl igi hl e at depths less than 10 feet. Also, the data of table 3 show alow silica content at depths less than 10 feet. This is in accord with thelow kaolinite perc en tage s shown at similar depths as shown in table 1.Thus, even though the differential thermal data differ from those of chemicalanalyses, the same trends are shown; namely, low silica or kaolinite accompanied by high alumina or ~ibbsite at depths less than 10 feet andincreasing silica or kaolinite accompanied with decreasing alumina orgi bbsl te at lower depths. Subsequent investigation indicates that a largeproportion of the alumina exists as hydrated ferruginous-alumina gel and thusis not reflected in the differential analysis.
SUMMARY
Borings were made in a gibbsitic area within the Wailua Game Refuge ofKauai, The area was excavated for an experiment in revegetation of asimulated stripmined area.
Differential thermal analyses of soils from the borings showed thatwithin the first 10 feet, gibbsite predominates over kaolinite, but between 10and 20 feet, there is a gradual decrease in ~ibbsite which is accompanied bya sharp increase in kaolinite. Also within the first 10 feet, material retainedon a 60-mesh sieve is substantially higher in ~ibbsite than is either theless than 60-mesh fraction or the unfractionated soil. Within this depth (1 to10 feet) the content of kaolinite in the fractions and in the unfra ctionate dsoil averaged but 2 to 3 percent.
Within the 10- to 20-foot depth, ~ibbsite was higher in the grea ter than60-mesh fraction than in either the less than 60-mesh fraction or the unfractionated soil. However, kaolinite content of this fraction did not differmaterially from that of the unfractionated soil.
Chemical analyses showed that the gi bbaite percentages obtained fromrapid differential thermal procedures underestimated the alumina present inthe 1- to 10-foot depths and that its values could not be used to evaluate theore for commercial purposes. These data indicate a large portion of thealumina is in a hydrated amorphous state, probably a ferrugin ou s-al uminou s~el.
LITERATURE CITED
1. Norton, F. H. 1939. Critical study of the differential thermal method forthe identification of clay minerals. Jour. Amer, Ceramic Soc. 22:54-63.
2. Sherman, G. Donald. 1958. Gibbsite-rich soils of the Hawaiian Islands.Hawaii AW. Expt. Sta, Bul. 116.
10
AP
PE
ND
IXLa
Tab
le1.
Dif
fere
nti
alth
enn
ald
ata
from
fiv
eb
ori
ng
sin
the
East
exca
vat
ion
site
Hol
eN
o.
1H
ole
No.
2H
ole
No.
3
Dep
th,
Sam
ple
Gib
bsi
te,
Ka o
lin
ite,
Sam
pIe
Gib
bsi
te,
Kao
lin
ite,
Sam
ple
Gib
bsi
te,
Kao
lin
ite,
feet
num
ber
per
cent
per
cen
tnu
mbe
rp
erce
nt
per
cen
tn
um
ber
per
c en
tp
erc
ent
I58
-1
811
058
-84
818
058
-9
88
110
258
-28
200
58-8
58
290
58-
9913
190
358
-3
816
058
-86
831
058
-10
08
310
458
-4
820
058
-87
84
10
58-1
018
210
558
-5
827
058
-88
837
058
-102
836
06
58-
68
290
58-8
98
420
58-1
03
85
20
758
-7
837
058
-90
B38
058
-104
817
08
58-
88
250
58-9
1B50
058
-105
814
09
58-
98
270
58-9
2B27
058
-10
68
1714
1058
-10
829
058
-93
B38
058
-10
78
158
1158
-118
1410
58-9
48
170
58-1
08B
935
12
58-3
98
1410
58-9
58
275
58-1
0 98
03
1....
13
58-4
08
465
58
-96
813
1358
-11
08
0.....
1458
-41
832
1058
-97B
1514
58-1
11
80
2215
58-4
2B20
1058
-11
213
05
016
58-4
38
1720
58-ll
3B0
40
1758
-44
812
2058
-114
B0
2418
58-4
513
1420
58-1
15
80
54
1958
-46
814
2020
58-4
7B15
40
21
58-4
88
05
222
58-4
98
74
32
358
-50
1311
2324
58-5
1B
1023
2558
-52
80
4326
58-5
3B
035
2758
-54
B0
5328
58-5
585
4229
58-5
6B8
4030
58-5
7B31
2131
58-5
8B35
18~2
58-5
9B5
7933
58
-60
83
4834
58-6
1B0
63
APPENDIX 1b
Table 1. (Continued)
Hol e No . 4 Hoi e No. 5
Depth , Sampl e Gibbs i te, Kaolinit e, Samp le Ci bbsite, Kaolinit e,
fe et number p erc ent p er cen t numb er p er cent p ercent
1 58-227B ~6 0 58-245B 12 02 58-228B 33 0 58- 246B 18 03 58-229B ' 23 0 58-247B 23 04 58-230B 42 7 58-248B 43 05 58-231B 24 12 58-249 B 25 06 58-232B 23 9 58-250B 39 07 58-233B 45 9 58-251B 60 08 58-234B 13 18 58-252B 45 09 58-235B 13 21 58-253B 39 0
10 58-236B 22 47 58-254B 50 011 58-237B 6 73 58-255B 43 012 58-238B 5 41 5~-256B 39 213 58-239B 24 69 58-257B 33 014 58-240B 0 9 5 58-258B 24 315 58-241B 3 44 58-259 B 18 016 58-242B 6 72 58-260B 39 617 58-2 43B 2 88 58-261B 33 1018 58-244B 3 4 8 58-262B 25 019 58-263B 26 16
12
APP
EN
DIX
2a
Tab
le2.
Dif
fere
nti
alth
erm
ald
ata
from
eig
ht
bo
rin
gs
inth
eW
est
exca
vat
ion
site
I--'
Col
j
Dep
th,
feet 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Sam
ple
nu
mb
er
58-2
64B
58
-26
5B
58
-26
6B
58
-26
7B
58-2
68B
58-2
69B
58
-27
0B
58-2
71B
58-2
72B
58
-27
3B
58
-27
4B
58-1
93B
58
-19
4B
58-1
95B
58
-19
6B
58-1
97B
58
-19
8B
58-1
99B
58
-20
0B
Ho
leN
o.
Gib
bsi
te,
per
cen
t
23 24 27 46 23 29 23 17 19 24 15 21 14 3 11 3 3 7
Kao
lin
ite,
per
cen
t
o o o 2 o o 3 3 8 15 4 921 30 24 63 33 41
Sam
ple
num
ber
58-1
83B
58-1
84B
58-1
85B
58-1
86B
58
-18
7B
58-1
88B
58-1
89B
58-1
90B
58-1
91B
58-1
92B
58-1
75B
58-1
76B
58
-17
7B
58-1
78B
58-1
79B
58-1
80B
58-1
81B
58-1
82B
Hol
eN
o.2
Gib
bsi
te,
per
cen
t
15 13 31 18 16 21 17 12 14 17 6 1 2 3 8 6 19
Kao
lin
ite,
per
cen
t
o o o 8 21
2 9 3 10 24 29 22 56 65 31 69o
Sam
ple
nu
mb
er
58-3
19B
58-3
20B
58-3
21B
58-3
22B
58-3
23B
58-3
24B
58-3
25B
58-3
26B
58-3
27B
58-3
28B
58-3
29B
58-1
30B
58-1
31B
58-1
32B
58-1
33B
58-1
34B
58-1
35B
58-1
36B
58-1
37B
58-1
38B
Hol
eN
o.3
Gib
bsi
te,
per
cen
t
15 19 15 14 12 14 13 6 11 13 11 15 21 21 9 7 5 o o o
Kao
lin
ite,
per
cen
t
o o o o o o 2 21 15 22 16 29 21 9 49 25 53 51
AP
PE
ND
IX2b
Tab
le2.
(Con
tinu
ed)
Hol
eN
o.4
Hol
eN
o.5
Hol
eN
o.6
Dep
th,
Sam
ple
Gib
bsi
te,
Kao
lini
te,
Sam
ple
Gib
bsi
te,
Kao
lin
ite,
Sam
ple
Gib
bsi
te,
Kao
lini
te,
feet
num
ber
per
cen
tp
erce
nt
num
ber
per
cen
tp
erce
nt
num
ber
per
cen
tp
erce
nt
158
-308
B20
058
-286
B14
058
-275
B8
0
258
-309
B·
230
58-2
87B
170
58-2
76B
100
358
-310
B27
058
-288
B20
058
-277
B8
44
58-3
11B
360
58-2
89B
204
58-2
78B
270
558
-312
B21
058
-290
B30
058
-279
B8
36
58-3
13B
230
58-2
91B
190
58-2
80B
153
758
-314
B32
058
-292
B13
958
-281
B37
0~
858
-315
B23
058
-293
B5
658
-282
B19
0~
958
-316
B7
658
-294
B12
1358
-283
B0
510
58-3
17B
330
58-2
95B
114
58-2
84B
22
1158
-318
B16
1058
-296
B11
658
-285
B5
1612
58-1
66B
1725
58-1
48B
1514
58-1
57B
2539
1358
-167
B15
2058
-149
B10
4558
-158
B11
1458
-168
B23
1158
-150
B8
1558
-159
B20
15
1558
-169
B23
1358
-151
B4
1358
-160
B17
33
165
8-l
70
B23
1958
-152
B4
3958
-161
B11
19
1758
-171
B7
2158
-153
B-
-58
-162
B0
33
1858
-172
B19
3658
-154
B-
-58
-163
B7
13
1958
-173
B14
3758
-155
B5
3258
-164
B0
2058
-174
B0
4158
-156
B50
3'2
58-1
65B
033
._- - - - - ---
APPENDIX 2c
Table 2.(Continued)
Hole No.7 Hol e No.8
Depth, Sample Gibbsi te, Kaolinite, Sample Gibbsite, Kaolinite,feet number percent per cen t number p ercent p ercen t
1 58-297B 20 0 58-218B 34 02 58-298B 18 3 58-219B 33 03 58-299B 17 6 58-220B 33 04 58-300B 15 10 58-221B 15 45 58-301B 14 11 58-222B 36 56 58-302B 30 3 58-223B 17 137 58-303B 12 24 58-224B 17 108 58-30 4B 12 25 580225B 13 209 58-305B 14 22
10 58-306B 8 42 580226B 3 6711 58-307B 4 4412 58-139B 0 42 58-211B 1 8213 58-140B 0 6 4 58-212B 4 2514 58-141B 0 64 58-213 B 1 5715 58-142B 9 28 58-214B 3 7016 58-143B 0 20 58-215B 2 4417 58-144B 0 72 580216B 0 4718 58-l45B 0 63 58-217B 0 6019 58-146B 0 7520 58-147B 0 60
15
I.
UNIVERSITY OF HAWAIICOLLEGE OF TROPICAL AGRICULlURE
HAWAII AGRICULTURAL EXPERIMENT STATIONHONOLULU, HAWAII
LAURENCE H. SNYDERPresident of the University
MORTON M. ROSENBERGDean of the College and
Director of the Experiment Station