Mining and quarrying wastes utilization in Ghana
Citation for published version (APA):
Hammond, A. A. A. (1986). Mining and quarrying wastes utilization in Ghana. Technische Hogeschool
Eindhoven. https://doi.org/10.6100/IR244274
DOI:
10.6100/IR244274
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Published: 01/01/1986
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IN GHANA
IN GHANA
(Hergebruik van mijnafval in Ghana)
PROEFSCHRIFT
TER VERKRIJGING VAN DE GRAAD VAN DOCTOR IN DE TECHNISCHE WETENSCHAPPEN AAN DE TECHNISCHE HOGESCHOOL EINDHOVEN, OP GEZAG VAN DE RECTOR MAGNIFICUS, PROF. DR. F.N. HOOGE, VOOR EEN COMMISSIE AANGEWEZEN DOOR HET COLLEGE VAN DEKANEN IN HET OPENBAAR TE VERDEDIGEN OP
DINSDAG 22 APRIL 1986 TE 16.00 UUR DOOR
ALEX AMPIM AMMA HAMMOND
GEBOREN TE KINKAWE, OSU ACCRA (GHANA)Prof. ir. P.C. Kreijger en
IN GHANA
THESIS
To obtain the degree of doctor of Technica! Sciences at the Eindhoven University of Technology, by the authority of the Rector Magnificus, professor dr. F.N. Hooge, to be defended in public in the presence of a committee nominated by the Board of Deans,
on Tuesday 22nd April, 1986 at 16.00 hrs.,
by
ALEX AMPIM AMMA HAMMOND
born at Kinkawe, Osu Accra (Ghana)Prof. ir. P.C. Kreijger and
The studies recorded here were eerried out under the Supervision of the First Promoter, Prof, Ir, P,C, Kreijger of the Department of Building, Architecture and Planning of the Univarsity of Technology, Eindhoven, whose advice and direction I gratefully acknowledge. I am also grateful to the Second Promoter, Prof, Ir. H.J, Th, Span of the Technological University, Delft, Civil Engineering Department for his advice and useful suggestions,
I should also thank Dr. M.D. Gidigasu, Director, Building and Road Research Institute, Kumasi for his encouragement; Mr. G.o. Kesse, Director
of Ghana Geological Survey, Accra for valuable geological data and
Dr. K,A.B. Asihene, Director, Institute of Mining and Mineral Engineering, Univarsity of Science and Technology, Kumasi for useful suggestions and ad vice.
Vany thanks are due to the Ghana Chamber of Mines and the Trustees of Valco Fund for funding ~ tr~vel to Eindhoven for the defence of this thesis,
Finally, I wish to thank Miss Margaret Ama Yeboa Ofori-Boateng for typ ing the draft and · the final script.
Alex Ampim Amma Hammond, Deputy Directerand Head, Materials Division
of the Building and Road Research Inetitute of the Council for Scientific
and lndustrial Research, Kumasi WRS born on the 18th December, 1931 at Kinkawe, os~ near Accra,
He studied Civil Enr,ineerin~ at the Belfast Collepe of Technology from 1964-1968 ann holds an M,Sc, Degree in Materials Science from the Uni verRLty of Science ancl Technology, Kumasi,
Befare joining the Council for Scientific and Industrial Research in 1969, he hAd worked with Sir WHl iam Halcrew and Partners, Accra from
1951,-19')9 and with the Queens University of Belfast Materials Testine Station from 1959-1968 as Technica! Officer, From 1969 to 1983, Mr, Hammond
hlls heli! vari.ous oositions in the Council as Chief Technica} Officer,
Senior Research Officer, Head, Materials Division and Principal Research O:'fi.cer, In 198':· he was appointed Deputy J)irector of the Institute,
As a pprt-time lecturer of the University of Science and Technology, Kum11Si, Mr, Hammond has lectured in Soil F.nf"ineer"ing and Soil Mechanics at the J)ecartment of Civil Fngineerinr. anè
•·lH'
a joint Teänical &iitor of the nroceedinf'S of the 7th Reg,ional' Cor.ference for Africa on Soil Mechanics and Foundation Er.fineering. He has also superviseil students' project work both in the Departmer.ts of Civi.l Engineering and Building Technology,Mr. Hrunmonil hii.S carried out extensive rese?rch on local buildill€ m~tteriRls, participated in Intern11tional Conferences, Seminars and Symposia nnd hns publ ished technica! papers on Construction materials, He has been a consul tEmt to UNF.CA, UNCHS (HABITAT) and FAO on local buildinp materials developmer.t in Africa.
He serves as R memher on a number of national and international committees, a few of which could be mentioned aa:
Development Planning Commission, Ghana.
ii. The Adviscry Board of Local Construction Materials Development
of the Ministry of Works and Housing, Ghana.
iii. The Board of Directers of Ankaful Brick and Tile Company, Cape
Coast, Ghana.
iv. The Management BoiU'd of the Building and Road Research Institute,
Kum11S i, Ghana.
v. The Advisory Committee of the International Committee on
Unconventi.onal construction materials Technology - U.S. A.
vi. The International Work Group of the CIB or. Util ization of
industrial waste in construction, The Netherlands.
vii.
RILEM
TC - 84 AAC - Committee on Application of Admixtures for concrete, France.viii. Executive member of the Univarsity of Science and Technology
Chaplaincy Board, Kumasi, Ghana •
.
Mr. Hammond is married and has three children, a daughter and two son.s.
CHAF'l'ER 1. 1 1. 2 1.} 1.4 1. ') 1. 6 1. 7 1. 8 CHA?l'ER 2 2.1 2.2 2.3 2.4 2.5
2.6
CHAPI'ER 3 3.1 3.2 3.3 ACKNOWLED~EMENTS LIST OF TABLES LIST OF ILLUSTRATIONS SUMlfARY INTROOOGTIONThe importance of the building materials and construction industries in Africa
Demand situation
Costs and prices of capital works in ~hana International policy on local building production ~hana national pol icy on local building materials production
Significanee of mining utilization A va Uab i1 ity of waste
Objectives and Scope
1 ITERA TURE RF/ IEW Introduetion
Types of mining and quarrying wastes Location, quantities, disnosal and starage Proparty evaluation
Uses for mini.ng and quarrying wastes 2. 5.1 Civil engineering construction 2.5.2 Roads/Highw~s
2. 5. 3 Bu lid ing materials production 2.5.3.1 The Ceramic industry 2.5.3.2 The Cement industry 2.5.3.3 Lightweight aggregate and
components
Benefits and 1 imitations in the use of mining and quarry wastes
GIDLOGY OF GHANA Introduetion
Pnysical geograp~
General descr ipt ion of the geology
viii.. V xiv xviii XX 2 4 5 7 7 8 11 11 14 23 24 24 27 30 31 32
3.4 Kinerale of economie importance 3.5 nescription of formations
3. 5.1 The Dahomeyan system
3. 5.2 The Birrimian eystem and associated granites ••• 3. 5.3 The Terkwaian system
3. 5.4 The Togo series • a. 3.5.5 The Buem formation 3.5.6 The Voltaian formation
3.5.7 Devonian formation, Upper Jurassic and Cretaceous - Eoeene
3.5.8 Superficial deposits (Quartena~ - Recent) CHAPl'ER 4 A SURVEY OJI' MINING WASTES OF GHANA
4.1 Introduetion
4.2 Location, and distribution of mining wastea 4.2.1 Prestea and Obuasi gold mines 4.2,2 Tarkwa gold mines
4.2.3 Dunkwa-on-Offin gold mines 4.2.4 Nsuta manganese mines 4.2.5 Akwatia diamond field 4.2.6 Awaso bauxite mines 4.3 Ra te of product ion of wastea 4.4 •ethods of disposal
4.5 Quantities of Stockpiles 4.6 Present uses
CH.A.Pl'ER 5 IIEI'HOOOLOGY AND EXPERIMmTALS 5.1 Introduetion
5.2 Methodology
5.2.1 Sampling and sample preparatien 5.2.2 Testing schema 5.3 Experimentals 5.3.1 Chemical tests 38 40 41 41 42 42 42 43 43 41:. 45 45 45 45 45 48 49 49 49 50 50 51 53
54
54 54 55 56 56 5.3.1.1 Silicate and complexametrie methode... 565.3.1.2 Tri-acid methods 6o
5.
3.
2 .ineralogioal tests5.3.2.1 Petrologicel examinatien 5.3.2.2 Differentiel Thermal analysis
ix.
63 63 63
5.4 Phys ie al and mechanical properties 5.5 Geotechnical properties
5.6 Engineering properties
5.7 Durabil ity of the w113te aggregates
CHAPI'ER 6 CfiDIICAL PROPERTIES OF THE MINING WASTES 6.1 Introduetion
6.2 Chemical properties
6.2.1 Oouasi and Prestea mining wastea 6.2.2 Nsuta mining wastea
6.2.3 Tarkwa mining wastea
6. 2.4 Dmkwa-on-Offin mining wastea
6.2.5 Awaso mining wastea
64
64
6567
69
69
70 70 70 71 7576
CHAPI'ER 7 KINERALOGICAL PROPERTIES OF THE MINING WASTES 78
7.1 Introduetion 78
7.2 Obuasi, Prestea and Tarkwa mining wastea 78
7.3 Dunkwa-on-Offin mining wastea 79
7.4 Nsuta mining wastea 79
7.5 Awaso mining wastea 79
7.6 Significanee of the chemical and mineralogical
studies 80
CHAPTER 8 PHYSICAL AND MECHANICAL PROPERTIES OF THE MINING
~ 84
8.1 Introduetion 84
8.2 Physical and machanical properties
84
8.2.1 Prestea gold mines 8.2.2 Obuasi gold mines 8.2.3 Tarkwa gold mines
8.2.4 Dunkwa-on-Offin gold mines 8.2.5 Nsuta manganese mines 8.3 Statistical analysis of the results
8.3.1 Computation for the statistical analysis CHAPTER 9 GIDTECHNICAL PROPERTIES OF THE IIINING WASTES
9.1 Introduetion 9.2 Prestea gold mines
x. 85 85
87
87 88 9596
98
98
98
CHA.PrER
9.4
Nsuta manganese mines9. 5 Awaso bauxite mines 10 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8
ENGINEERING PROPERTIES OF THE MINING WASTES Introdu ct ion
Conorete with coarse aggregate from mines Compressive strength of cubes
l'lexural strength of beams
Modulus of elasticity of the concrete cubes· Avraso bauxite waste pozzolana
Review of the resulta •••
Statistica! analysi.s of the resulta of the compressive strength of concrete cubes
99
99
103 103 103 103 108 108 110 112 118 10.8.1 Computation for the statistica! analysis 120 CHAPI'ER 11 11. 1 11.2 11.3 11.4 11.5 11.6DURABILITY OF THE MINING WASTES Introduet ion
Soundness tests of the coarse mining waste aggregates
Drying and wetting of the coarse mining waste aggregates
Evaluation of the coarse mining waste aggregates for alkali-aggregate reactivity
Evaluation of the effectiveness of the bauxite waste Pozzolana for preventing alkali-aggregate rel\ctivity
Evaluation of the reaiatanee of the ba.uxite waste pozzolana to aome chemical attack •••
11.6.1 Reaiatanee to sulphate attack 11.6.2 Reaiatanee to sea water attack
11.7 Drying shrinkage of concrete with the eol\rse mining waste aggregates ·
CHAPTER 12 l!lNIRONMFNTAL AND HEALTH HAZARDS 12.1 Introduetion
12.2 Stab U ity of tips
12.3 Radioact{vity oi' the mining wastea
12.4
Environmental pollution 12.4.1 Arsenie oxides 12.4.2 Acid rain xi. 122 122 123 126 127 130 130 130135
135
141
141 142 143 145145
147CHAPTER 13 13.1 13.2 13.3 13.4 13.5 13.6 13.7 13.8 on the environment
ANALYSIS AND DISCUSSlONS Introduetion
Location and availabil ity of mining wastes Chemica! properties
Mineralogical properties
PhYsical and mechanica! properties
13.5.1 Grading, shape, and surface texture of the mining wastes
13.5.2 Specific mass ••• 13.5.3 Water absorption
13.5.4 Machanical properties - aggregate Crushing value, aggregate Impact value and Los Angeles abrasion
13.5.5 Coefficient of variation of results Geotechnical properties
13.6.1 Atterbergs limit
13.6.2 Maximum dry density, Optimum moisture content and Natural moisture content 13.6.3 C.B.R. - California Besring Ratio Engineering properties
D.lrability properties •••
13.8.1 Soundness test of the coarse mining waste
150 154 154 154 155 158
161..
164
165 166 166 167 169 169 169 170 172 171 ... ~~~~~1A
13.8.2. Drying and wetting test of the coarse
mining waste aggregates 175
13.8.3 EValustion of the coarse m<n<ng waste
aggregatas for alkali-aggregate reactivity 176 13.8.4 Evalustion of the effectiveness of the
bauxite-waste pozzolana for preventing
alkali-aggregate reactivity... 177
13.8.5 EValustion of the resistance of the
bauxite-waste pozzolana to some chemical attaok 179 13.8.6 D~ing shrinkage of concrete with the
coarse mining waste aggregates 180
Environment hazards and heal th influenc ing properties
xii.
14.2 Civil engineering and builaing congtruction 14.3 Building materials industries
14.4 Expected benefits from using the wastea CHAPI'ER 15 CONCLUSIONS AND RECOMJIENDATIONS
15.1 Introduetion 15.2 Conclus i ons 15.3 Recommendations
15.4 Guidelines for poliey formulation and implementation REPERENCES .APPENDICES 2
3
4 5 xiii. 183 183184.
185 188 188 188 193 194 196 209 210 215 222243
2.1 Yearly production and stockplle of coll iery spoil (After 19) •••
2.2 Kining and quarrying wastes, production and stockpile (Adapted from 18 and 22)
2.3 Chemical analysis of some tailings (After 22)
2.4 Typical chemical analysis of raw and burnt rejects (Aftar 29)
2.5
Gompaaition of burnt and unburnt British colliery ahales (in weight percent) (After JO)2.6 Typical chemical analysis of basalt fines (Aftar 31)
2. 7 Chemielil anlllysis of waste china cla,y sand
(Ad lipt ed from ( 27) )
2.8 Comparative mineralogical analysis of colliery spoils (weight
%)
(Aftar 19)2.9 Utilizlltion of colliery spoil (After 19) 2.10 Present uses of mining and quarrying wastas
(AdRpt ed from ( 19))
3.1 TRble of Succession (After (19)) 4.1 Mining areas in Ghana
4.2 Summary of locRtion, production rata (103 ton/year) Rnd stockpile (103 tons) of mining wastas in
5.1
6.1 6.26.3
6.1..6
.5
6
.6
GhMaTesting schema for the concrete cubes made from the mining WRStes
Chemielil composition of grRnite, gRbbro-diorite grRnodiotite
Chemielil composition of mangani.ferous oxides Chemielil campos it ion of manganiferous carbonates Chemie lil composi.ti.on of phyll i. tea
Chemica! campos i t ion of quartzite from Tarkwa Chemie al composi.tion of sandstone f'rom Tarkwa 6.7 Chemical composi.ti.on of alluvial deposits of
Dunkwa-on-Offin wastea
6.8 Chemielil composition of bauxite and bauxite-waste from Awaso
6.9 Chemica! analysis of tbe partially replaced oement with the pozzolana
xiv. 17 18 19 20 20 22 28 29 40
46
51 67 71 7172
73 74 75 75 7677
8.1
Summary of test results of the coarse mining wastea from Prestea gold mines8.2 Summary of test results of the coarse mining wastes from Obuasi gold mines
8.3 Summary of test results of the ooarse mining wastes from Tarkwa gold mines
8.4
Summary of test results of the coarse mining wastea from Dunkwa-on-Offin gold mines8.5 Summary of test results of the coarse mining wastea from Nsuta manganese mines
8.6
Summary of coefficient of variatien of the test results of all the mines8.7 Tabulation of means from Tables 8.1-8.3
9.1 Summary of geotechnical test results of the fine wastes of Prestea gold mines
9.2
Summary of geoteohnical test results of the fine wastas of Dunkwa-on-Offin gold mines9.3
Summary of geotechnioal test results of the fine waste of Nsuta manganese mines9.4 Summary of geotechnical test results of the fine mining wastes of Awaso bauxite mines
10.1
Compressive strengthof concrete oubes made with Ob u as i mining waste and cured for 7 d!\}'B10.2 Compressive strength of concrete cubes made with Obuasi mining waste and cured for 28 days 10.3 Compressive strength of concrete cubes made with
Dunkwe-on-Offin mining waste and cured for
7
days 10.4 Compressive strength of concrete cubes made withDunkwe-on-Offin mining waste and cured for 28 d!\}'S 10.5 Compressive strength of concrete cubes made with
Prestea mining waste .and cured for
7
days10.6
Compressive strength of concrete cubes made withPrestea mining waste and cured for 28 days 10.7 Compressive s'trength of concrete cubes made with
Tarkwa mining waste and cured for 7 d!\}'s
10.8 Compressive strength of concrete cubes made with Tarkwa mining waste and eured for 28 d!\}'s 10.9 Flexural strength of beams made with mining
waste and standard aggregates at 28 d113s 10.10 Modulus of elasticity of concrete cubes made
from mining wastas and also from standard fine and coarse aggregates
xv.
86
8688
89
89
95
96
99
100 101 101 104 104 10~ 105 105 106 106 106109
110calcined bauxite-waste pozzoliUla from Awaso on concrete
10.12 Gomparisen of compressive strengthof concrete cubes between mines
10.13 Summary of results from computation
10.14 Tabulatl'en of means from Table 10.11 on the basis of mix and type of specimen
10.15 Tabulation of means from Table 10.11 on the basis of mix and age of specimen •••
11.1 Results of aggregate soundness test of coaree aggregates of Prestea mining waste using saturated sodium sulphate salution
11.2 Results of aggregate soundness test of coarse aggregates of Prestea mining waste using saturated magnesium sulphate salution
11.3 Results of aggregate soundness test of coarse aggregates of Obuasi mining waste using saturated sodium sulphate salution
11.4 Results of aggregate soundness test of coarse aggregates of Obuasi mining waste using saturated magnesium sulphate salution
11.5 Results of aggregate soundness test of coarse aggregates of Tarkwa mining waste us ing saturated sodium sulph1\te salution
11.6 Results of aggregate soundness test of coarse aggregates of Tarkwa mining WA.Bte using saturated magnesium sulphate salution
11.7 Resul ts of aggregate soundness test of coarse aggregates of Dunkwa-on-Offin mining waste using saturated sodium sulphate salution 11.8 Results of aggregate soundness test of coarse
aggregates of Dunkwa-on-Offin mining waste using saturated magnesium sulphate solution 11.9 Effect of drying and wetting tests on water absorption and aggregate crushing value of coarse aggregates of Prestea mining wastas 11.10 Effect of drying and wetting tests on water
absorption and aggregate crushing value of conrse aggregateaof Obuasi mining wastea 11.11 Effect of drying and wetting tests on water
absarptien and aggregate crushing value of conrse aggregll.tes of Tarkwa mining wastee 11.12 Effect of drying arrl wetting tests on water
absorpt ion and aggregate crushing value of coarse aggregates of Dunkwa-on-Offin mining wast es xvi. 112 118 119 120 120 124 124 125 125 125 126 126 126 127 128 128
129
11~13 Results of tests to evaluate the coarse mining waste aggregates for alkali-aggregate reactivity 11.14 Results of resistance to sulphate and seawater
attack- cement replacement by pozzolana 11.15 Resul ts of resistance to sulphate and seawater
attack- addition to pozzolana
11.16 Drying shrinkage for fine and coarse aggregates of Prestea mining wastea
11.17 Drying shrinkage for fine and coarse aggregates of Tarkwa mining wastea
11.18 Drying shrinkage for fine and coarse aggregates of Obuasi mining wastes
11.19 Drying shrinkage for fine and coarse aggregates of Dunkwa-on~Offin mining wastea •••
12.1 Quality factor or relative biological effective-ness {R.B.E.) for converti.ng absorbed doses to do se e qu i val ent
12.2 llaximum permissible levels of ionizing radiation
12.3
Arsenic content in samples collected at the premises of Ariaton gold mines Prestea (After Sandi and Farmilo (105))12.4
Arsenic content in samples collected at the premises of Ariaton gold mines Prestea (After Sandi and Farmilo (105))12.5
Arsenic content in urine samples from Prestea {After Sandi and Farmilo (105))12.6 Arsenic content in hnir samples from Prestea {After Sandi and Farmilo
(105))
12.7
Arsenic samples from Obuasi (After Amasa (104))12.8
Maasurement of pH of rainwater in three miningare as xvii. 129
135
137
140 140 140 144 144 148 148 149 149 149 1501, 1 3,1 4.1 4.2 4.3 8,1 8,2
8.3
8,4 8.') 9.1 10,1 10.2 10.3 10.4 10,') 10.610.7
10.8 10,9 10.10Schemati~ diagram of the Scope of the Stu~ Simplified geological map of Ghana
Map of Southern Ghana showing Mining Locations Picture of stockpils of mining waste at Obuasi Picture of stockpile of mining waste in relation to some of the residential areall of the mines at Obuasi
Partiele size distribution of mining waste from Prestea
Partiele size distribution of mining waste from ObUASi
Partiele size distribution of mining waste from Tarkwa
Partiele size distribution of mining waste from Dunkwa-on-0 ffin
Partiele size distribution of mining waste from Nsuta 10 39 47
52
')2 90 9192
9394
Partiele size distribution of bauxite wastea 102 Sieve analysis of fines from the wastea forconcrete 107
Sieve analysis of crushed mining wastea for
concrete 107
Partiele size distribution ourves of aggregates
for the control concrete specimens 111 Strength distribut ion histograms of concrete cub es
made from Obuasi mining wastea 113
Strength distribution histograms of concrete cubes
mAde from Prestea mining wastea 113
Strength distribution histograma of concrete cubes
made from l>unkwa-on-Offin mining wastea 114 Strength distribution histograms of concrete cubes
made from Tarkwa mining wastea 114
Strength distribution histograms of concrete oubes
of mining wastea from the four mines 11') Strength development of concrete cubes from the
mining WAstea over a period of one year cured
in water at 25°C 116
Relationship of strength development of pozzolana cement concrete cubes cured at 25°C in water
with time ... 117
11.1 Photomicrographs of 8 section of concrete under-going Alkali-8ggreg8te reaction (3 months) 11.2 Photomicrographs of 8 sectien of concrete
under-going Alkali-aggregate reaction (6 months) 11.3 Photomicrographs of a sectien of concrete
under-going Alkali-aggregate re8ction (9 months) 11.4 Photomicrographs of 8 section of concrete
under-going Alkali-aggreg8te reaction (12 months) 11.5 Photomicrographs of a section of concrete
containing 40/Go% pozzolan8 cement (3 montha) 11.6 Phótomicrographa of a section of concrete
containing 40/6CJ1> pozzolana cement (6 months) 11,7 Photomicrographs of a section of concrete
containing 40/6o% pozzolan8 cement (9 months) 11.8 Photomicrographs of 8 section of concrete
containing 40/60% pozzolan8 cement (12 months) 11.9 Specimens befare test (Resiatance to seawater
attack) 11.10 Specimens
attack)
after test (Resistance to seawater 11, 11 Set up of drying shrinkage maasurement of
concrete prisms
12.1 Flow diagram of the roasting operations at the Ariaton gold mine, Prestea •••
A,1 Relation between crushing strength 8nd water/ cement ratio for 4-in cubes of fully compaoted concrete for mixes of various proportions A.2 Graphical combination of ag~regates
A.3
Graphical combination of aggregatesxix. 1'•• 131 1 ~ 1 132 132 1)3 1))
134
134 138 138 139 146 212 213 214SUMMARY
The noed fO!' bullding materials in Ghana am in the davaloping African eoonolliY as a whole is a reflection of the measured need for
houses, schools, factories, offices, roads, dams, harbeurs and communication and other facilities as well as of the rising quality standards and users requirements for bulldings ani facilities. Indeed, a pre-condition for development in GhaM and other African nations is to bulld up their
infrastructure.
The provision of illfrastructure wlll necessarily generata a great demand for such building materials as sand, crushed rock, bricks, tiles arxl cemont in large quantities. This damend r~J~zy in turn result in local depletion of the naturally available materials which are traditionally used for construct ion.
At the saJDB time, there are conoentrated in some areas, where there are mines~ heaps of mining wastea which cannot be disposed of in an economically and environmentally acceptable menner. If the mining wastas possess adequate chemical, p~sical ~nd engineering properties and satist,y certain economie requirements for construction, they can be profitably used for construction. This will lead to conservation of natural resources and
energy and reduction of problem of environmental pollution posed by the waste materials.
The objeotive of the study was to evalluate the chemioal, m.ineralogioal, plzysical and meohanical, geotechnical and enginasring properties of the mining wastes. The potentiel of the waste materials as haal th and
e!l'fironmental oontaminants was also evaluated. Pozzolana was developed
from the bauxite-waste and its strength and effect against sulphate attack of concrete was evaluated,
MI well as other modified standard lll!lthods were used.
A survey of the availability, location and quantities of the mining wastea of eight minif18 areas of Ghana (Prestea, Obuasi, Tark:wa, Dunk:wa-on-Offin, Nsuta, Ak:watia, A.wasro and Konongo) - r e undertaken. The survey revealed that there· are available 136 mUlion tons of mining wastea in Ghana covering an area of 1090lai ( 109 thousand hectares).
Chemically and mineralogically the mining wastea were found to be stable. They contain no deleterious watèr soluble substanoes that would leach out. But the wastea from Tark:wa, Obuasi and Prestea contain small amounts of pyrites. This oalls for pretesting of the waste befere use
in concrete.
The specifio masses of the waste material range from 2680 to 2770kg/m3 with water absorption of 0.25,1o to 0.49;{. The Nsuta waste gave the highest water absorption of 12.8%. This indioates a poreus and weak aggregates.
The aggregate crushing, impact and Los Angeles abrasion tests gave results comparable to those of oonventional aggregates. The values indicate that the aggregates are strong and though with good reaiatanee to impact, crushing and abra.sion. The coeffioient of variatien of the results of the ooarse materials from all the mines are in the sameorder for the ~peoifio mass. That for the water absorption is relatively low
oempared to those for flakiness index and crushing value. Materials from Dunkwa-on-Offin gave the least ooeffioient of variatien for four of five.tests. This suggests less variability of the waste materials.
The soa.ked C.B.R. of the mining waste r8f18ed from 12.1% to 142%. the highest and lewest values given respeotively by materials from Prestea and DunlDra-on-Offin.
The frequenoy distribution of oompressive strength of all the samples from all the mines used as r.ggregates in concrete show that 28% of the samples
4DN/mi;
40 to 44N/IDII2 and 10% ranging from 44 to ~N/am2.The modulus of elasticity derived from the 28 d~s cube strwngth ranged from 28.04 to 28.33KN/mm2 and oempared favourably with the control value of 28.8kN/mm2• Evidently1 the standard aggregates can be replaced with the mining waste provided they can be obtained at economie haulage distances.
From the soundness test, the alkali-aggregate reaction, sulphate resistance, dfying and wetting and shrinkage tests it was eTident that the waste materi.als are durable for use as aggregates in building and road
construct ion.
The pozzolana developed from the bauxite-waste can replace up to
40%
of Portland cement in concrete and aohieve at 28 d~s87. 2!'/o
of.
the control strength. The pozzolana was found to be less effective in combating sulphate attack.s,The mining wastea per se are not poisonous neither are they dangerous to handle, nor radioactiva but the tips of the tailings ray be proned to erosion whioh may in turn pose stability problems.
In addition to using the mining wastea for oonstructing roadl!, rail, and houses as well as for other engineering works, the taUinga may be used for manufaoturing glass, bricks, tiles and for providing pigments for the pa int industry, Pozzolana-oements ~ be manufaoture• from the bauxite-waste.
RecoMmendations are made for the intensifioation of the use of waste lllll.terials in construotion; monitoring of the performance of projeotl!
oonstruoted with mining waste and writing up specificatien for such materials.
Samenvatting.
ne behoefte aan bouwmaterialen in Ghana en in de zich ontwikkelende Afrikaanse econo111ie als geheel, vloeit voort uit de behoefte aan woningen, scholen, fabrieken, kantoren, wegen, dijken, havens etc. zowel als uit de gewenste kwaliteiteverhoging en de verhoogde gebruikerseisen die worden gesteld aan gebouwen en faciliteiten. Voorwaarde voor de verdere ontwikkeling van Ghana en van andere Afrikaanse landen ia de verdere opbouw van de
infrastructuur. Infrastructuurvoorzieningen zullen noodzakelijkerwijs leiden tot grote vraag naar bouwmaterialen zoals zand, gebroken rots, bakstenen, dakpannen en cement. De grote hoeveelheden die hiervan nodig zijn zullen
resulteren in lokale tekorten van de natuurlijk aanwezige materialen die traditioneel worden gebruikt voor constructies.
Tegelijkertijd zijn er in de mijndistricten grote bergen mijnafval aanwezig die men niet op economische en milieuvriendelijke wijze heeft kunnen gebruiken. Indien dit mijnafval geschikte chemische, fysische en bouwtech-nisch aanvaardbare eigenschappen bezit en tevens aan bepaalde economische
.voorwaarden voor toepassing voldoet, kan dit met voordeel voor constructies worden gebruikt. Dit zal leiden tot besparing van natuurlijke hulpbronnen en van energie en kan deproblemen van vervuiling door de afvalmaterialen reduceren.
Het doel van het onderzoek was om de chemische, mineralogische, fysische, 111echanische, geotechniache en bouwtechnische eigenschappen van het mijnafval
te evalueren evenals de mogelijke gezondheidabeinvloedende eigenschappen. Puzzolanen werden vervaardigd uit bauxiet-afval en de invloed hiervan nagegaan op sterkte en sulfaataantasting van beton 111et toevoegingen van deze puzzoli;UlBn. Bij deze evaluaties werden B.S.-,A.S.T.K.- en A.A.S.H.O.-normen evenals aan het onderzoek aangepaste standaardmethoden gebruikt. Eenoveraioht wordt gegeven van beschikbaarheid, locaties en hoeveelheden
on-Offin, Nsuta, Akwatia, Awaso en Konongo). Uit dit overzicht blijkt dat er 136 millioen ton mijnafval in Ghana is dat een oppervlakte beslaat van 1090
km~
Het mijnafval bleek chemisch en mineralogisch duurzaam te zijn en geenschadelijke in water oplosbare producten te bevatten die later zouden kunnen u i tlogen. Maar het mijnafval van Tarkwa, Ob u as i en Prestea bevat wel kleine hoeveelheden pyri&t zodat bij gebruik als toeslagmateriaal in beton dit materiaal hierop eerst zal moeten worden onderzocht.
De soortelijke massa van het mijnafval varieert van 2680 tot 2770 kg/m
3
en de waterabsorbtie van 0,25 tot 0,49%m/m. Het Nsuta-mijnafval had evenwel een waterabsorbtie van 12,8% hetgeen duidt op een poreus en zwak materiaal. De crushing-,impact- en Los Angeles afslijtproeven op het mijnafval gaven vergelijkbare resultaten met die van conventionele materialen. De gevonden waarden geven aan dat het mijnafvalmateriaal hard is en goede weerstand heeft tegen impact, breuk en afslijting. De variatiecoefficient in de meetresul- -taten van de soortelijke massa van het grove mijnafvalmateriaal had voor alle mijnen dezelfde grootte orde; die in de waterabsorbtie blijkt relatief laag vergeleken met die in de vlakheidsindex en in de breuksterkte. Materialen afkomstig van Dunkwa-on-Offin gaven voor vier van de vijf typen proeven de laagste variatiecoeffici.ent. Dit' suggereert d11t het mijnafval weinig in kwaliteit varieert.De Wilarde VM de natte C.B.R.-proef VM het mijnafval varieert van 12,7% tot 142%, welke waarden respectievelijk werden gevonden voor de monsters
afkomstig van Prestea en Dunkwa-on-Offin.
De frequentieverdeling van de druksterkte van beton vervaardigd met monsters mijnafval van alle mijnen toonden aan dat 2&,% VM de proefstukken een
28-2
dagen sterkte had gelegen tussen 36 en 40 N/mm , 62% een variatie had van
2 2
40-44 N/mm en 10% van 44-46 N/mm •
De elasticiteitsmodulus, afgeleid van de 28-dagen kubusdruksterkte varieerde
van 28800 N/mm. ruidelijk blijkt dus dat het gebruikelijke toesl~~g~Deteriaal, technisch gezien, goed kan worden verrangen door het afvalmateriaal van de mijnen, uiteraard als dit materiaal ook economisch qua afstand ligt. Uit het onderzoek naar de duurzaamheid, de mogelijkheid van alkali-toeslag
reacties, de sulfaatweerstand, de resistentie tegen drogen en benatten en de dregingakrimp bleek duidelijk dat het mijnafvalmateriaal ook duurzaam is bij gebruik als toeslagmateriaal in beton en bij gebruik in de wegebbouw. Het uit het bauxiet-afval vervaardigde puzzolaan kan tot
40%
portlandcement in beton vervangen en daarbij na 28 dagen verharden 87,2% van de sterkte van de controleproefstukken bereiken. Het puzzolaan bleek echter minder effectief te zijn ten aanzien van eventuele sulfaataantasti~.Het mijnafval bleek geen giftige bestanddelen te bevatten en niet radioactief te zijn, noch is het gevaarlijk te achten voor de gezondheid bij bewerking tot bouwmateriaal. Wel zijn de uitlopen van de mijnbergen onderhevig aan erosie wat eventueel kan leiden tot stabUiteitsproblemen bij de mijnbergen. Naast gebruik van het mijnafval voor wegen en spoorwegen en voor bouwkundige toepassingen is gebruik ook mogelijk bij de vervaardiging van glas,
bakstenen, dakpannen en pigmenten ten behoeve van de verfindustrie. Puzzolaan-cement kan van het bauxiet-afval worden vervaardigd.
Aanbevelingen worden gegeven voor intensiever gebruik van het afvalmateriaal in constructies, het uitvoeren van projecten waar het mijnafVal wordt gebruikt en ten aanzien van het opstellen van normen en specificaties voor het gebruik van de afvalmaterialen afkomstig van de mijnen.
1. INTRO OOGTION
1. 1 THE D!PORTANCE OF THE BUILDING MATERIALS AND CONSTRUCTION INDUSTRIES IN AFRICA
The building materillls and construction industries are the basic meiUUl for the implementation, expansion, impravement and maintenance of all civil engineering works and human settlement projects and therefore constitute ene of the most important industrial sectors in the national economy. There is net a single human activity in which construction and building materials are nat involved. Whether it be the sector designed for tP.e creation or
impravement of tte basic structures for economie development, the sectors necessa.r.y for the satisfaction of social needs, or the sectors involved in the cultural life of a nation, these industries are the first to beoome ooncerned in providing the framewerk and fa.vourable conditions for the full development of such sectors (1).
The building materillle industr.y and the construction industr.y are so closely related that they are generally considered as one sector. Any upward or downward change in the v.olume of construction will have a proportionate effect on the building materials industry, As construction is ver.y flexible, it can expand,and contract significantly in response to sca.ttered, fluctua-ting and discontinuous demand. This can be observed frequently in Africa following the initiating and completion of major infrastructural works such as dams, large irrigation schemes, airports and harbeurs (2).
In the industrialized countries progress in building is generally
taken to mean progress in all sectors. This is one way of a.cknowledging that the construction industry in generlil and the building materials industry
in particular may be taken as highly sensitive, lilmost infallible indicators of a oountry's economie and social health. As a matter of fact, in E.Jrope and the United States, for example, the construction sector has even become
a political factor and a real war-horse which must be reckoned with at the
time of elections since it is well known that this sector has direct or
ir-direct repercussions on family needs And hence ultimAtely on the needs of
the el ectorate (3).
The importance of tre building materials and construction industries
for the economy, particularly during the first phase of development of the
Af'ri can countri es, 1 i es in the fa ct thr.t A substant i al part of the scarce
resources available must be invested in construction. The African nations
ought to build up their infrastructure as A pre-condition to development.
For example, the gross fixed capital formation of Africa in
1975,
has been estimated at approximately$US 19
billion, more than50%
of which was accummul11ted by construction and bui.lding mAterials, I t can be assumed thatat current price levels and labour rates, building materials repreeent more
than
50%
of the total investment in construction. Thus, the1975
expenditure on building materials may be estimated at about $US 5 bill ion. Recent estimates also show that more than half of these materials were imported,which means that more than $US 2.5 billion in foreign currency is being spent annually by African countries to import building materials (1).
1. 2 Da!AND SITIJATION
The need for building materials in the developing African economy
therefore is a reflection of the measured need for houses, schools, factories,
offices, rcads, dams, harbeurs And communication and ether facilities as well
as of the rising quality stAndArds and users requirements for such buildings
and facilities. It is estimated that by the year 2000 the number of people
living in the cities of the less developing countries will be twice as much
there are today (4). This expansion of population will require facilities
which will in turn generate a great demand for building materials and
components.
3.
African region with regard to various types of building materials required for the execution of building and housing programmes because of psucity of data, But it is certain however, that in many countries the formal construc-tion sector experiences severe shortages of essential building materials which are highly priced, sametimes far above the official prices set by government, If the current trends are allowed to continue without any efforts to evereome the inbalance between the supply and de'lland of building materials the gap between the two is bound to increase in the ruture for a number of reasans including the following:i, the demand for building materials will continue to increase because of high urbanization rates requiring new housing and infrastructural as well as accelerate development programmes in a number of countries; ii, the current dependenee on imparts to meet a substantial
portion of building materials needs cannot be sustained by many governments because of foreign exchange constraints; iii, local plants for the production of building materials
have failed in many countries to make an impact on the building rnRterials market
(5).
Historically, African countries have met a substantial portion of their requirements for conventional building materials through imparts as mentioned earlier, The slow pace of growth of local production has not helpad to reduce this dependency which has become increasingly difficult for many countries to finance.
The African regional damend situation is practically the same as that of Ghana. Specifically, in Ghana, the effective demand for buildings and facilities, ia directly dependent upon the tinanclal ability of the country's private end public investors to requisition and purchase its capital works,
This ability does not only depend on the investors financial reserves and resources of finance, but l'':l the increasingly higher co st of material s, plant
and labeur, expreseed in higher unit cast of the capital works. 1,3 COSTS A.ND PRICES OF CAPITAL WORKS IN GHANA
While the cast of labour is regulated locally by the nati.onal control of wages and salaries, the casts of many basic materials, equipment and construction plant are at the mercy of the oversaas market especially for those goeds whi.ch have to be i.mported into Ghana. In turn, the abi.lity to import such goods is dependent on the foreign exchHnge earned through national exports, the sterling or dollar value of whi.ch are tending to lag behind the price of the imparts urgently needed for the capital works equipment and construction programma,
Proporti.onately, therefore, the prices of finiehed capital works are rising much faster than the i.ncrease in the private and public fund2 that can be allocated to capital works expenditure, AS a direct result, the actual areas of useful building space being produced year by year is falling behind the calculated requirements, In addition, the same fixed output of
us&ful building space is also declining because of the general need to raise the standards of construc~ion and equipment and public demand for better
fp._cilities9 The 1 inkage of the construction i.ndustry with the building materials in:lustry as mentioned earlier, is such that any upward ar downwArd change in the volume of construction activity reflects proportionately on
t~e building mater-ials i.ndustry,
Inversely, therefore, one of the major factors contributing directly to the low national output of houses needed in the urban areas and i.ndirectly to the poor qu
u
i. ty of houses in rural are as in Ghana is the high cast of imported buildine; mnterials. There is the need therefore for manufacturing buil:line; materials from local raw materials and i.ndustrial wastes, such as-n lning wastes,
1, I._ OOERNATIO!lAL POLICY ON LOC AL BUIL DI~!G PRODUCTION
5.
course, not new. It has long been reoognized by maqy developing as well as developed oountries, and its importance to the economie development and stability of such countries has been widely acknowledged and emphasized. The United Nations in particular, through many of her organizations has advocated for development of building materials indust~ as part of her economie develop-ment programme for the developing countrtes. In 1965, a General Assembly resolution recommended that developing count~ governments should take allnecessa~ measures to develop a building materials industry by utilizing l~cal
raw material s to the maximum ( 6).
Later, at the International Symposium for Industrial Development held in Athens in 1967, it was recommended that developing countries should, where appropriate give high priority to the development of building materials industries in order to achieve a greater efficiency in their construction activities (7). Since then various meetings and conferences have edopted many resolutions and recommendations dealing with the great need for imprave-ment in the construction indust~ and in the building materials industry subsector.
The most recent International Conferences at which important decisions regarding the construction and building materials industries were taken include the United Nations Conference on Human Settlement held in Vanecuver in May and June, 1976 (8), the Fourth Conference of Ministers of
E.C.A.
held in Kinshasa in Februa~, 1977 (9), the Fourth Conference of African Ministers of Industry held in Kaduna, Nigeria, in November, 1977 (10) and at aSymposium held in Nairobi in 1983 on Appropriate Building Materiala for Low Coat Housing and organized by CIB, RILFl!, UNCHS, UNESCO, UNECA and CEC (11). 1.5 GHANA NATIONAL POLICY ON LOCAL BUILDING MATERIALS PRODUCTION
The provision of adequ_ate housing in decent human settlementa which satisfy not only the physical and biologica! requirements of man but will slso uphold his dignity and improve the quality of his life is a basic human
necessity. The Government of the Republic of Ghana is committed to the
impravement of the quality of life in all human settlements for the presentand future generations of Ghanaian citizens especially those who form the under privileged sections of the population.
In recent ycnrs considerable national effort has been expended on the exploita-tion of availl>.ble resources with vnrying degrees of success for the achievement of the objective of a better qunl ity of 1 ife for all in all human settlements in the country (12).
Housing is only one of the physical requirements that sustains human settlements. A n;>.tional houaing pol icy and execution programme aimed at achieving thc objectives in such a pol icy should therefore net be 1 imited solely to thc provision of housing but should take account of the totality of
hum~n community, whether city, town or village and give adequate consideration
te all the social, material, organizational and cultural elE'!Dents that
sustain the human community. These elements include the physical requirements for housing, water and sanitation, services for education, health and cultural f'aci.l ities for reereatien and leisure. These elements will require buildil18 materials and components.
In Ghana imported material5 ac~ount for a large share of construction cast which may range from 50-5~; the foreign currency spent for this purpose hns now increaaed to an unacceptable level. Planned action is needed to repl<'lce imparts and te develop an efficiently werking dornestic building materials inè.uatry. A consi<lerable shnre of national resources is te be
invested in developing materials industries. These industries in turn will depend on loc al raw m<'l.teri<'l.l s includil18 industrial wast es (mining wastea ).
There is every reason, therefore, for Ghana's national policy objective of subst i. tut ing to an increas ing ex tent - building material a made from loc al
raw materials and industrial wastes. Nat only will soaree roreign exchange thereby be conserved, but there is a goed chance that some of the rises in price of ,,,aterials and components could be halted and, in addition, a definite
7.
contribution could be made to stahilizing the unit coats of useful building space created by builders.1.6 SIG-NJli'ICANCE OF MINING WASTE UTILIZATION
The mining industry produces large quantities of inorganic industrial waste. In countries like Ghana, where mining is a major industry there are therefore large tips of mining waste materials, the presence of which do not only mar the landscape but can causa despoliation and environmental pollution.
As most of these wastea consist mainly of sand, gravel and crushed rock the construction industry uses large quantities of these as aggregates. In recent years, however, attention has increasingly been focussed on the possibilities of using waste materials directly as alternatives or indirectly as raw materials for producing other construction materials such as bricks, pozzolanas and Portland cement.
Naturally, there are limitations to the utilization of waste materials and because of that the materials must fulfil the performance requirements in terros of engineering and physical properties as well as chemical and
mineralogical composition so as to identify and exclude any deleterious materials which might cause instability or other forma of failure in use.
Research into the nature and properties of mining and quarrying wastea is therefore vital for identifying suitable materials and for establishing the basis for developing standerds which can be written to proteet the user and thereby creating more confidence in the usage of the waste materials. 1.
7
AVAILABILITY OF WASTEMining activities started in Ghana many centuries ago but it was not until 1860 when a modern type of mines was established in Prestea in the principal goldfields in Western Wassaw. Later in 1897 the Ashanti G-oldfields Corporatien was formed to work the Concession of 26o sq.km. {100 square miles) which had been aarlier acquired in the Obuasi district. The other mines at
befere the Firat World
wa:r
or soon Rfter it (13, 14, 15 & 16).As an extractive induatry the Operatiens of the mines naturally produce lllrge quant i.ties of bul ky WRStes. As R re sult the operRt ions of these mines over the years hRve led to the accumulation of large quAiltities of mining wastea in piles or tips ar in retentien dams, the stock pile of which runs
into mill ions of tons. Where they exist as tips and pil es they have been unsightly Rnd have pose many environmentl\1 problems.
Most important of these problems a:re these posed by the stabil ity of the tips which have alw~s been a souree of risk and hazRrd to life and
properties in U•e mines; and these due to pollution of air, water and lAild by substance leaohing out from tips of mining waates. In order to reduce the
env ironmental problemr associated with the storRge and d isposal of the wast es, and to conserve bath enera and nRtural resources uses must be found for them. One of the arel\e where the wastea can be profitably utilized is in construction.
Ag~regates, particularly, coarse aggregates, a:re a major component of materials required for construction and maintenance of roads and buildings. The avai.lability, distribution and cast of aggregates are therefore major
economie factors for consideration in construction. If the mining wastea
possess adequate engineering propert~es and satisfy certAin economie require-ments for construction, their use will not only give the mi.nes additional rcvenue through a ales, but as earl i er menti.oned, natu ral resources, aggregates
anè energy for winning it will be conserved. This will lead to the reduction
of the problems posed by the wastes. 1.8 OBJECTIVES AND SCOPE
The purpose of this study is to evaluate the chemical, mineralogical, physical, geotechnical and engineering properties of the waste materials. To identify uses for the waste materiRis directly ar through the manufacture of building materials from them. And finally, to assess their potential as
9.
health hazard and as environmental contaminants: leaching out of heavy metals,
taxicity of the waste material and radio-activity of the waste materials. In order to achieve these objectives a literature survey will be carried out as well as a survey of the distribution, location and quantities of the wastee, The waste materials will be assessed fortheir suitability employing BS and ASTM Standard Testing Methods, The data so obtained will be organized and interpreted. During the interpretation, the data will be fully discussed
and the application and uses derived from the interpretation will be ap~lied
to construction in general but particularly, to roads and buildings and the expected benefits from the study evaluated and recommendations given, Based on the recommendations pol icy guidel i nes will b e formulated as to judicieus planning of future mines so as to enhanoe the ready use of waste as they are produced. Figure 1 shows a schematic diagram of the scope,
DEC I SION MAKING Policy guidetines
EXECUTIOH AND ~ formulJJtion
ADMINISTRA TIO N lmpll m ontat1 on . and .
l
_t_
..
0::: PROBLEMS .2i
ldentification 0:::..
Definitjone
AnalYSISe
r - -J
..
..
u...
Noturat Environmentol Land'""L
f-
Resource Po Hution Mis u se..
-- 0 : : :ii ..
~ ~
SURVEY"'
e e
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Location...
·-
...
-
Literature1
Types and auantitie s...
!::.Ë1 .... ....!!!...-0::: z: z:
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-;i
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PRO PERTY :::.'-<C( EVALUATION ...~....
Chemicat Physicat
~~eotechnicatl
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-
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~
<C( and and and Durabitity u
co Mineratoaical Mechanica! Engineerin!l
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APPLICATIOH-
lnterpretation-
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2, LITERATURE
REVIEW
2.1 INTRODUeTION
For the past fifteen years, many countries including the United States, the United Kingdom, the Netherlands and others from B.Jrope, Africa and As ia. have carried out surveys and assessment; of waste materiills and industrial by-products. In addition, such Interrlll.tiona.l bodies as the Organization for Economie Co- oparation and Development (OECD), the InterMt ioni\1 Uni on of Test ing and Research Laboratories for Material s and Structures ( RILE1t!), and the International Council for Building Research Studies and Documentation (CIB) as well as the American Society for Testing Materials (A~TM), have also carried out surveys of waste materials ( 18, 19),
The main reasans for undertaking such surveys are the need to conserve soaree natural resources, reduce environmental polJution and to conserve energy. In identifying the raasons underlying these surveys and ~tssessments
in the United States, Bortz (20) attributes the basic realities th11.t ne cessi-tates industrial waste evalu~ttion and utilization in the United States to:
i. A strong, continuing demand for mineral resources of all kinds from ever - widening number:s of sources.
i i, A steep rise in the price of mnny mineral s and industrial oommodities after dec~tdes of relativa price stability.
iii, A continuing development in oversaas cartels to control sourees of supply of primary metals.
iv. The mounting problems and casts to industry to meet ever-stricter environmental specifications to cut down on pollution. v. An ever-growing need to conserve industrial energy, power and
consequent rel iance on util izing mineral resources which will best achieve that end.
vi, The continuing pressure to strengthen delicate balance of peyments position.
Anothcr reasen is that the expansion and maintenance of transportation facilities rcquired by growing popul~tions and urbanization is dependent on
a large supply of low-cost raw materials such as sand, grRvel, crushed stone,
lime, Portl~.nd cement and asphal ts. The increasing demand for crushed stone,
sand 11nè grf_vel, the conventionlil bulk constituents, is closely -paralleled by
requirements for building construction. In many areas, the increased
consump-t~cn of construction materials has been out-p11cing the population increase, as
the per capita demand is also rising steadily. Again, at the same time when
dem11nd for 11ggregRte is rising the economie sourees 11re being depleted,
daterio-rating in qulll i.ty, or becoming unavailable bec11use of environmentlil proteetion
regulations, zoning restrictions and appreciating land villues in developing
~:'eRs. The objectives in carrying out such surveys have been universally the
s1une al tr.ough the scope has naturlllly differed •. This review confines i tself
to mining ar.d quarrying wastes.
A distinction is us~ally made between mineral mining and quarrying
wastes ancl coal refusc. V/astes from sizing and cleaning of coal, from either
underground mining or from strip mining operations, are defined as coal
refuse. Goal refuse miiJ contain mine rocks, carbonanceaus shale, pyrites and
other debris from mining operations. , Dredge spoils are also covered in this
sectien because their mineralopiclll compositions and physical states are like
these of mining wastes (
22).
Mining wastes are the coRrse waste which are derived from rock blastings and at tunnel preparation stages of mining, thereare nlsc the tailinfS from milling of the ore. Quarrying wastes are surface
overburden materials, which must be removed and disposed of to gain access
to the ore or the profitable rock
(18, 19,
20,22).
These include wastes from gold, copper, lead, zinc, iron, bRuxite, Rnd taconite ore mines andslate, china cliiJ and crushed stone quarries. The coarse wastes are heaped
as tips and tailings derived from the milling of these ores are deposited in
13.
these tips are further incentives and justification for assessing the waste materials for utilization in construction.2.2 TYPE OF MINING AND QUARRYING WASTES
Two types of mining and quarrying wastes m~ be identified as the waste rock and mill tailings. The waste rock consists of pieces of stanes grading from boulders to gr11vels. It is a stony mixture of materials which, depending on the condition of overburden l~ers, varies greatly in grading. The mill tailings are the residues obtained from the separation of minerals from their ore (18, 19, 22). The mill tailings grade from coarse sand to fine silt to cl~s. The characteristics of the waste are influenced by the methad of processing the ore.
2.3 LOCATION. QUANTITIES. DISPOSAL AND STORAGE
Coarse mining and quarrying wastes are dumped on lands as close to the mines as possible. Fine wastes, tai.lings, are usually conveyed by pipelines as slurries into d!Uils or lageons at the mines. Table 2.1 summarizes the quantities, production and stockpile of colliery spoil of aleven countries. Much of the slurry water is recirculated or allowed to evaparate resulting in the formation of slimes in the case of lead-zinc tailings, bauxite and same-times in the case of iron and capper tailings (22, 25, 26). Tailings are also disposed of through u se as mine backfill materials. The coarse tail ings are aften stockpiled (24, 26).
In Australia (29) it is common practica to dispose of coarse wastea by land fill, orten in gullies, and the slurry into old werking or into ponds
or dams formed from embankments or coarse waste to facilitate dewatering and drainage. These methods of disposal are unsatisfactory both to the local community because of the environmental pollution and to the mining industry itself because of disposal casts. Slurry poses the greater problem since it can easily seep into streams and, in some cases, it m~ take years for slurry ponds to dewater and dry out, particularly if clays such as bentonite
or montmorillonjte are present.
Table 2,2 summarizes the quantities and stockpile of ether mining and quarryi.ng wastes. From thè two tables i t can be observed that the U. S.A. is the biggest producer of waste bath in quantity and vari.ety. It is also true that in many mining countries as much attention has not been devoted on waste ev?..lu atl on and ut 11 i.2.at ion as in the Uni. ted Stat es, In most developi.ng countri.es, for example, most of their envircnmental pollution problems which attn\Ct maximum attention have been those on sanitation, There is need to evaluate and use wastes stockpile for construction ei.ther directly or indirectly through the manufacture of bui.ldinp: materii\J.s,
2.4 PROPERTY EVALUATION
In order to evaluf.te the waste materi.als for their suitability for construction i t is important to assess their chemical, mineralogical, physical and other properti.es. Thi.s will enable identi.fi.cation and exclusion of any deleteriouE mnterials which mi.ght cau~e instabil ity or other farms of failure in use.
For this reasen chemical and mineralogical analysis have been carried out extensively on mP.r,y mi.ning and quacrying wastes. F.valuation of physical prcpert i es has been 1 imited in the 1 Herature. It has been observed that the physicP..l and chernical properties of the mill tailings depend on their souree and the methad of ore processing, Tailings from lead/zinc mining are often dolomitic (24), while these from taconite, gold and capper ore mines have high silica content ( 25). Table 2.3 shows typical oxide analyses of taconite, copper, gold and lead-zinc tailings,
Tabl e 2.4 and 2. 5 are typical chemie al analysis of colliery wast es from Australia (29) and Bri.tain (30) respectively. The burning of the Wallte leads to reduction in the propertien of combustible matter, to the partial decom-position of the clay mineral, to the decomposition of carbonates and to the oxidation of the sulp.hides to soluble sulphates, This may be accompanied by
15.
voltatile compounds into the atmosphere, Tables46 and 2,7 summarize the chemical properties of basalt fines And waste china cl~ respectively, Basalt is quarried extensively in various parts of Australia (31) as an aggregate for road making and for concrete, During quarrying, a fine dust (accounting for over 10% of the rock removed) accumulateB when the b~~alt
is crushed, These fines are classified as unsuitable as aggregate for aqy other useful purpose, and are usually discarded in unBightly spoil heap, troublesome on windy d~s. As shown in Table 2.6, the material contains relatively large amount of transition and alkaline metals and has low melting point compared with conventional raw materials used in the Ceramic Industry (31), Table 2,7 shows the chemical analysis of waste from china clay, China cl~ is largely composed of kaolinite, a ~drated aluminium silicate (Al4Si4
