BURIED TREASURE
S.Narayana Moorthy

BURIED TREASURE

Resources
Exploiting a geologically disturbed limestone deposit
Buried reserves
Manual working
Mechanized working
Massive Deposits
Summing up
The possibilities
Who can involve
A ROADMAP

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.