ABSTRACT
Mining history in Liberia is
often plagued with difficulties of uncertainty of commercial quality and
quantity of mineral existence in a particular region. Previous studies
conducted at Mount Tokadeh, study area which lies between latitude 7o15’N
and 7o45’N and longitude 8o15’W and 8o45’W was
distributed in three ore zones; the Oxide Ore, Transitional Ore and Primary
Ore. It was also proven that there is some considerable amount of silica and
alumina in this ore deposit but the extent of these impurities within this ore
deposit were unknown.
The main aim of this research was to investigate the use of
information gain from kriging interpolation techniques (Ordinary Kriging,
Indicator Kriging and Universal Kriging) to estimate iron ore resources and
categorize selective mining unit as High Grade Ore (HGO) or Direct Shipping Ore
(DSO).
Field data were processed in excel template and exported
into shapefile format inputted into ArcGIS/Arcmap 10.2.1 for interpolation
using three main kriging interpolators. Four classes of creative colors were
used to delineate the relative quality of mineral distribution within mining
site. The final output maps (Prediction map, Probability map and Error of
Prediction map) were obtained. Voxler was used to model borehole data in 3D
format and was overlayed on the output kriged map for validation. The results
showed that Indicator Kriging which uses threshold was the best interpolation
method that categorizes the various mining units. Integrated method using
Kriging in GIS was introduced and implemented in this work to determine the
prospect of using this approach in mapping the spatial division of iron, silica
and aluminum content and tonnage of iron ore.
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND
Before 1989, Liberia was the world’s sixth largest exporter
of iron ore which was contributing to as much as 64% of total exports and 25%
Gross Domestic Product (GDP). However, there has been no production until 2003,
making the iron ore sector a prime mover for economic growth (Chadwick, 2011).
Liberia’s mineral development policy and mining code
envisaged that exploitation would be balanced appropriately with sustainable
environmental preservation (MLME , 2010). Other laws governing the mining
sector in Liberia, particularly the National Environmental Protection Agency of
Liberia’s Environmental Protection and Management Law, (2002) required a
mandatory environmental impact assessment prior to exploitation (MFA, 2003),
and the facilitation of conservation of the biological diversity of Liberia.
These require the use of knowledge driven exploitation of minerals in order not
to degrade the land in search of such, at places without a high probability of
ore finds.
Geostatistical methods and Geographic Information Systems can
provide the necessary tools for ensuring knowledge-based and targeted
exploitation.
Geostatistics uses spatial and temporal patterning to exploit
the relationships that help to model potential values of a variable at
unsampled points, and these analyzed in GIS, would limit the search of minerals
to areas with high probability of mineral ore occurrences.
The mining industry is often plagued with difficulties mainly
due to uncertain existence of the prospected mineral of interest in commercial
quantities, the grade and tonnage available and the exact location within a
region where minerals are likely to be found. Previous studies conducted in the
study area show that ore deposits are distributed in three ore zones (Oxide,
Transition and Primary ore zones) (Amikiya, 2014). It was also established that
iron concentration increases with decreased silica content in all the ore
zones. However, the distribution of iron, silica and alumina in the three ore
zones is not known. The applications of geostatistics method can provide a
means of estimating both the grade and tonnage of the various grades at
unsampled points together with estimated errors. This would reduce the
uncertainty or investment risk and helps control the number of exploration
drilling requirement as well as establishing decisions to mine based on grade
and tonnage.
1.3 Aim and Objectives
1.3.1 Main Aim
The main aim is to investigate the use of information gained
from Indicator Kriging (IK), ordinary Kriging (OK) and Universal Kriging (UK)
in estimating Iron Ore resources and apply the best method to categorize
selective mining unit as High Grade (HG) or Direct Shipping Ore (DSO).
The specific objectives are to:
Use an integrated methodology of Kriging in GIS to
demonstrate the possibility of mapping the spatial distribution of iron, silica
and alumina in the ore deposit of the Tokadeh Study area.
Delineate the relative magnitudes (tonnages) using creative
colors to each mineral type at various locations of the study area.
Prepare Prediction maps, Error of Prediction maps, Quantile
maps, Probability maps and sampling point map for these mineral deposits using
GIS.
1.4 Scope of current work
This work is limited to Mt. Tokadeh concession area of
Liberia. The integration of geostatistics and GIS is used to predict the
mineral distribution of Tokadeh ore deposits using sampled data collected from
110 drilled bore holes. There are several geostatistical interpolation methods,
but in this research, the kriging procedures of interpolations (indicator
kriging, ordinary kriging and universal kriging) were used based on the
phenomena being studied. Variography is first done to determine which
mathematical method is best.
1.5 Relevance of research
The unavailability of estimated ore reserve grades and
quantities prior to mining have led to the failure of mining projects and
unnecessary degradation of biodiversity even where no ore exist
(Dimitrakopoule, 2012). The results of this effort would facilitate decisions
on deposit viabilities at different locations in terms of quality and quantity.
This research is compiled into 5 chapters.
An introduction presented in chapter one includes background,
problem statement, objectives, scope of current work, and relevance of
research.
In Chapter 2, a review of ore deposit classifications in
terms of mineral burden, geostatistical techniques and use in mineral
prediction and exploration are made. This chapter further includes challenges
of interpolation methods and their relative strengths and weakness.
The material and methodology employed in the current study is
presented in chapter
The results of current effort are in chapter 4. The chapter
also includes a discussion of these results and deduction made from these
analyses.
The conclusions drawn from the study are presented in chapter
5 together with some recommendations for further studies
For more Geomatic Engineering Projects Click here
===================================================================Item Type: Ghanaian Topic | Size: 73 pages | Chapters: 1-5
Format: MS Word | Delivery: Within 30Mins.
===================================================================
No comments:
Post a Comment
Note: Only a member of this blog may post a comment.