1. TITLE OF THE INVENTION: Development of Stoping Index for the Selection of
Optimum Stoping Method for Underground Hard Rock Mines using Rank Sum
and Rank Reciprocal Method
2. APPLICANTS)
a) NAME: Rajni Kant
b) NATIONALITY: Indian
c) ADDRESS: C/0 Shri Rakesh Mishra
Sai Nagar, Near Ashirwad School
Jhigabai Takli, Godhani Road
Nagpur 440030
Maharastra, India Field of Invention: Mining Engineering Type: New Concept
3. PREAMBLE OF THE DESCRIPTION:
Underground methods for exploitation of mineral deposits are employed when the depth of the deposit, the stripping ratio of overburden to ore (or coal or stone), or both become prohibiting for surface exploitation. Once economic analysis points to underground methods, the choice of a proper mining method is very critical in underground hard rock mines as it directly affects the ore recovery and dilution and amount of development needed. The mining methods also decide the level of technology required and in turn affect the type of equipment required, cycle time and chronological succession of operations, production (tonnes per year) and the risks (financial and operational) involved.
Each ore body is only one of its kind with its own properties, and decisions of choosing a mining method must match the properties of the ore body under consideration. Generally two or more feasible methods may be available as options for a mine planning engineer for a given deposit. Each method involves some advantages as well as inherent problems. Therefore, the optimal method is one that provides the least problems and best operational effectiveness. Although understanding of mining conditions and engineering decisions provide major input into the selection of a mining method, subtle differences in the features of each ore deposit has to be examined exclusively through a comprehensive analysis of the available information. Once an ore body has been established through suitable exploration and sufficient information has been gathered to justify further analysis, the next important step is to select the technically feasible methods of excavation for the deposit, followed by selection of the most appropriate one amongst them.

4. DESCRIPTION
Selection of Optimum Stoping Method through Stoping Index
A new indicator - Stoping Index (SI) has been developed for selection of optimum stoping method in underground hard rock mines. The index can be used effectively for selection of the optimum stoping method for a given deposit considering the site specific conditions of the deposit.


Figure 1. Methodology of development of Stoping Index for the Selection of Optimum Stoping Method for Underground Hard Rock Mines Rank Sum and Rank Reciprocal Methods
The development of Stoping Index for the Selection of Optimum Stoping Method for Underground Hard Rock Mines Rank has been carried out in three levels (three tier) as shown in figure 1 and as follows:
• Level (Tier) 1 - Application of Rank Sum Method (RSM) and Rank Reciprocal
Method (RRM) for the determination of the associated weights of main eight geo-
technical parameters identified for the purpose of this study.
Following factors are considered for the application of Ranking methods
1. Ore strength
2. Wall rock strength
3. Deposit shape
4. Deposit dip
5. Deposit thickness
6. Ore grade
7. Ore uniformity
8. Depth
• Level (Tier) 2 - Application of of Rank Sum Method (RSM) and Rank Reciprocal
Method (RRM) for the determination of the weights of five sub-parameters under
each respective main eight parameters.

Factor Scale (Attribute) Range of Values
Ore Strength 1 - (Weak) 0-20 RMR

2 - (Weak to Moderate) 21-40 RMR

3 - (Moderate) 41-60 RMR

4 - (Moderate to strong) 61-80 RMR

5 - (Strong) 81-100 RMR
Wall Rock Strength 1 - (Weak) 0-20 RMR

2 - (Weak to Moderate) 21-40 RMR

3 - (Moderate) 41-60 RMR

4 - ( Moderate to strong) 61-80 RMR

5 - (Strong) 81-100 RMR
Deposit Shape 1- (Tabular)

2 - (Lenticular)

3 - (Tabular to irregular)

4 - (Tabular & Massive)

5 - (Any)
Deposit Dip 1 - (Flat) 0-5u

2 - (Flat to Moderate) 6U-15U

3 - (Moderate) 16u-25u

4 - (Moderate to Steep) 26u-45u

5 - (Steep) 46°-90u
Deposit Thickness 1 - (Very thin) Less than 1.5 m

2 - (Thin to moderate) 1.5 m-3.5 m

3 - (Moderate) 3.6 m-5.5 m

4 - (Moderate to thick) 5.6 m-7.5 m

5 - (Very thick) More than 7.5 m
Ore Grade 1 - (Low)

2 - (Low to Moderate)

3 - (Moderate to Fairly High)

4 - (Fairly High to High)

5 - (High)
Ore Uniformity 1- (Highly Variable)

2 - (High to Moderate Variable)

3 - (Moderate)

4 - (Fairly Uniform)

5 - (Uniform)
Depth 1 - (Shallow) Less than 150 m

2 - (Shallow to Moderate) 150 m-300 m

3 - (Moderate) 301m-450m

4 - (Moderate to Deep) 451m-600m

5 - (Deep) More than 600m
• Determination of the Stoping Index (SI), which is a weighted sum of the weights obtained under the level 1 and level 2, for both the methods (RSM and RRM). The index quantifies the appropriateness of method for a set of site specific conditions referring to geo-technical parameters. Value of the index ranges between 0-1, and higher is the index value, more suitable is the method for the given site specificconditions. The expression for Stoping Index (SI) is given as -

Where Sli denote stoping index (/=l,2,..,,7);w,y denote the weight of /h geo-technical parameter(/=l, 2,...,8) corresponding to / stoping method; w'y refers to weight of chosen level (1 to 5) of/h parameter corresponding to ith stoping method.
The stoping index is the resultant weighted sum of the products of the weight of main parameter and the weight of scale (attribute) of that parameter selected for the given deposit condition. The stoping methods corresponding to top three SI values have been regarded as

the most suitable methods for the given deposit. SI values for a given deposit have been calculated for both the rank weighting techniques - Rank Sum Method andRank Reciprocal Method. Claim :
1. Development of Stoping Index
2. Calculation of Stoping Index values for both the rank weighting techniques - Rank Sum Method and Rank Reciprocal Method.
3. Development of the methodology for selection of optimum stoping method in underground hard rock mines for any given deposit using the Stoping Index following both the rank weighting techniques - Rank Sum Method and Rank Reciprocal Method.