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The diminishing resources of mineral as
well as social awareness to the environmental concerns for new mining
projects call for a serious look at the residual resources. The
threshold values are changing and technology makes for greater use of
raw material. This article looks at the scope of recovering the mineral
not tapped during the transitional stage between small and larger scale
of operations when the need for exploration did not gets its due
importance.
The article looks at the possibility of pooling resources, tapping
experience and knowledge of professionals, guidance of government
agencies and financial assistance from institutions to make workable
projects and adding to the national mineral inventory.
Introduction:
Mining becomes a gamble if not armed with full knowledge of the deposit
and the adequacy of data generated over the mining block has a direct
bearing on the successful exploitation. However, the regional setting,
the overall structure of the deposit and the structure and influence
within the lease area determine exploitation of the deposit to its
potential.
While the National Mineral Policy and the Act, Regulations, Rules and so
on framed there under, as well as the enforcement agencies guide and
help in proper mining and utilizing the mineral resources, the
influencing factors are:
Management policies and objectives
Available financial resources and ability to accommodate
development to potential
Mine management and operating personnel
Size of the operations and flexibility
Economic viability
The success of exploitation depends on the ability to generate data in
totality and ability to understand the intricacies and to plan according
to the dictates of the deposit. Every management with foresight
undertakes a project only after ascertaining the adequacy of the raw
material not only for the present capacity but also for future
expansions. However, there could be variations in the degree and density
of the exploratory programs, an attempt to protect investment and
against surprises.
In the case of small workings dependant on generation of revenue for
survival priority is to work within “visible limits” only. The demands
of the end users vary according to their capacities and limitations on
their own captive resources. The element of uncertainty does not allow
small individual operators for investment in detailed exploration and
full exploitation of a deposit. Major end users are keen to get only raw
material of good quality for augmenting their supply or for preserving
their own resources. The threshold values of each mine therefore varies
even though the end user could be the same.
Resources:
In the case of linear deposits extending over a length but with several
fragmented workings over its length, the entire potential of the deposit
is not assessed, each protecting, his/her own area of control. When
there is a competition, survival takes priority over conservation.
This generally results in shallow workings that focused on outcrops
worked to logical extensions. When confronted with space for lateral
expansion, contact zones, or need to go deeper, the workings move to a
better alternative available.
Unless the mines manager has the backing of the management in
developmental and conservation activities, the priority shifts to
production function and his attention if focused on meeting targets on a
daily or even shift basis and this factor will determine the working
blocks.
The totality of the deposit is lost unless the organization
carries out detailed exploration and determines the life of the deposit
and prepares a mining plan to work to its potential, and strictly
follows it up. The mining personnel then have a broader vision to keep
long-term interests and protect available resources. With depleting
resources and increasing competition and non-availability of additional
resources, necessity brings focus on the preservation and conservation
of available resources.
The threshold values keep changing all the time in line with
technological advancements and diminishing resources there is a need to
give a second look at the residual resources on a broader scale.
Exploiting a
geologically disturbed limestone deposit:
The workable Archaen limestone deposits of South India are generally
structurally disturbed. It has taken considerable time for the
transition from manual to mechanical operations.
The practice of “selective mining” determined the acceptable grade,
which varied from plant to plant depending upon availability with the
“Raw Mix” deciding the scope of mining. In the case of the outsourced
limestone mostly from small workings, priority was given to higher grade
and maintaining “factors of safety”.
The threshold values of different mines supplying to the same end
user also varied. Several workings had different standards and once
considered acceptable to one mine was unacceptable at the other mine. A
uniform standard would reveal the quantity left unexploited or disposed
off as waste and buried under dumps or used to fill pits in the mine
itself.
Deposits unless properly explored cannot be mined to potential
Buried reserves:
These kinds of deposits worked manually over a long time. Since the
priority of the piece-rated worker is to earn his wages, based on his
production, the easier pickings given priority, contact, and waste
material left in-situ. These pillars not only narrow down the operations
but also block further exploitation. The visibly exposed blocks worked
as individual blocks and if separated by contacts considered as rejects,
worked in isolation.
The persistence in the folded deposits left unnoticed when no attempt
made to study the geology, and work according to the dictates of the
geology. The size of the block determines the depth of workings and when
benches formed, further material is blocked.
There is also a possibility of disposing other potential minerals
as waste (as magnesia limestone associated with crystalline limestone).
When the priority of the mine is to supply a particular mineral and the
entire focus is only on that. This is more by default in large-scale
captive mines. For example, concentration of good grade limestone could
ignore the potential of associate magnesia limestone and dispose it to
the waste dump.
Manual working:
Limiting to visible blocks only
Since payment is on accepted quality often associated mineral is
ignored
Waste handling gets the least priority, normally used for maintaining
the floor and ramps involving several times “re-handling”
Mine workings are limited to commercial depth only.
Unless the management decides on a detailed study, the entire
operations are based on “knowledge”
Pillars are a common feature blocking further development
Focus shifts repeatedly on “discovered” good blocks
Mechanized Working:
In the case of disturbed deposits operations could be a mixture of
manual, semi mechanized as well as fully mechanized operations depending
on the size and uniform quality of the block.
Guideline exploration determines the run of the deposit and if it is
intricate, investment required to maintain the density of boreholes is
not readily forthcoming.
Many mines have their own geological wing including a survey team who
monitor on a daily basis but if the deposit is complicated and not
easily understood there is a necessity to call outside specialists which
is subject to the policy of the management.
However, it is required to pierce the contacts to provide a larger
working base the cost of development and policy of the management
determines the interlinking. In such cases, the exploitation is limited
to the depth of each block and the entire persistence is not considered.
When there is a need to segregate the run of mine before feeding to the
process, sorting takes place outside the mine on the surface.
This calls for:
Larger area for spreading over and control
Very strict control over recovery and invariably smaller pieces and
mixed boulders get lost when pushed to accommodate stock
The sequence calls for a high degree of organization and commitment in
view of large volumes. Unless recovery and sorting matches the run off
mine spread, there is always a chance of good material mixed with the
pushed material to waste dump.
Massive deposits:
These deposits form part of basins and runs into several kilometers long
and several kilometers wide. Invariably these deposits attract larger
players and the best indicated blocks are taken over with future in
mind. Sometimes smaller players could get wedged in or workings carried
out in isolation. There is always a tendency to have control over an
extent more than that required for either present scale of operations as
a buffer for future expansion or protecting own resources. When planned
expansion does not materialize or when there is a problem of plenty, the
need for conservation does not get its due attention.
Summing up:
Factors affecting Recovery
Size
Size of leasehold and extent over which surface rights are held is
disproportionate to the workings, need, and based on a generalized
workable depth instead of detailed exploration
Management
The investment policy and vision of the management on exploration, mine
development and conservation of mineral
Operations
Persistence –
working each deposit to a notional depth instead of its potential depth
Spread over leaseholds –
working in isolation and only what is considered blocks of uniform
acceptable quality
Contiguity –
when several mines are worked in the same deposit, contiguity is lost,
leaving isolated blocks
Size of leaseholds –
proportion to capacity
Responsible mining –
segregation of waste to accommodate changed threshold values and working
as per the dictates of geological structure
Reserves and lack of priorities –
geological inventory control and tracking.
Lack of Data
Smaller operators have different objectives and long term planning may
not be a priority
Deposits extending beyond leasehold and structure of deposit – The
potential may not come to surface unless the whole deposit is viewed in
totality
Smaller area with unknown geological features - Often worked to take the
easy pickings only.
No systematic exploration - applies to several workings
The Possibilities
1. The example considers only the case of some of the workings in
Archaen crystalline limestone with disturbed geological structure and
associated mining scenario.
2. The potential could be substantial if a total view is taken and the
knowledge and experience of all professionals are pooled and major
deposits are taken into account
3. If all the implementing agencies, mine managements currently
possessing and present in potential areas, professional geologists, mine
managers who have in-depth knowledge over such deposits act together
with the sole objective to unearth the “buried treasure”, the
possibilities could be substantial and the available knowledge would not
go waste.
The mining activities broadly viewed as:
Current operations New lease and Greenfield projects
Potential that could come under “buried treasures” which could include a
re -look at abandoned workings, closed mines, waste dumps, mining blocks
with substantial potential but lying in isolation as of now
Who can involve?
Managements
Managements holding surface rights and lease over potential deposits but
are unable to exploit the potential should come out with their
constraints and plans and seek assistance. They should be amenable for
joint workings where their capacity does not permit exploiting the full
potential of the deposit.
Professionals
The professional mine managers, engineers, geologists and other
competent persons who have worked for prolonged time in deposits with
potential but left untapped. They are the best source easily and cannot
only indicate the potential but also can participate in reclamation
programs. Active professionals with resources can involve and pool their
resources in the projects.
Government Agencies
Initiatives from the Government Agencies are required to iron out the
constraints for tapping the potential. Without the active participation
of the Government Agencies the whole process may get derailed
Financial Institutions
There is a need to assess each project to its individual merit.
Investment and financial assistance for initial development needed for
long-term gains. Institutions can participate in the projects to ensure
their realization on investment.
A Road Map
The entire potential of the deposits throughout the country to be
reviewed taking the present changing threshold values and pooling
experience
Identifying priority blocks and preparation of individual project
reports with:
Giving priority to managements already holding leases and surface rights
and who come out with proposals and seek assistance
Small operators lacking resources, skill or knowledge pooled to form
co-operatives for joint ventures.
Iron out the existing constraints and if necessary grant of one time
relaxation of the conditions and prepare a workable, long-term solution
involving the “resources-pool”.
Implementing Agency designated with necessary assistance for “plan of
operations”.
In the author’s view, the concept is not far-fetched and the firm belief
comes out of his experience during active service. Pooling the knowledge
and experience of professionals throughout the Country could bring in
substantial reserves. This will also give an opportunity to the present
mine managements to realize and exploit the deposits under their control
to the potential. An open mind from all agencies involved would be the
nation’s gain.
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