Claims:A composition useful as an alternative filling material for hydraulic stowing process in an underground mine, said composition comprising
I) overburden material of 2.1-10mm in the amount of 35% by weight;
ii) overburden material of less than 2mm in the amount of 35% by weight;
iii) sand of less than 15mm in the amount of 20% by weight;
iv) gypsum based putty in the amount of 10% by weight;
wherein the composition is treated with a heat at 300°C for 4 hours.
2. The composition useful as an alternative filling material for hydraulic stowing process in an underground mine as claimed in claim 1, wherein the overburden material includes mica schist, meta-sedimentary rock, calcite, sand stone, and dolomite.
3. The process for preparing the composition as claimed in claim 1 comprising the steps of:
i) collecting the materials;
ii) mixing the materials to form a homogeneous mixture; and
iii) treating the mixture as obtained in step (ii) with a heat at 300°C for 4 hours.
, Description:FIELD OF THE INVENTION:
The present invention relates to a composition. More particularly, the present invention relates to a composition useful as an alternative filling material for hydraulic stowing process in an underground mine. The present invention also relates to a process for preparing the composition.
BACKGROUND OF THE INVENTION:
At the onset, it is to be considered why the sand is used as underground filling Material in mines?
i. Sand is permeable and high strength which offer low compressibility, this is ideal condition for support of overhead structure/ strata’s;
ii. It maintains ideal geological condition inside the underground and avoid future subsidence;
iii. It maintains ideal condition for ground water and it’s flow;
iv. It avoids the problem related to pollution; and
v. It is non-reactive with minerals composition / chemicals.
The underground mines are using horizontal cut and fill method of stopping with post-filling of sand by hydraulic stowing operations since 1994. The river sand is scare material and in future the availability of river sand is in danger.
Most of mines of underground Mines are operated by using cutting and filling method and stop filling carried out by sand filling method. Present days are competition into market and increase in trends in production as well as excavation of sand inside the river bed is also increased.
Due to environmental conditions and stringent laws and rules, the availability of river sand is very poor. Moreover, in future insufficient sand supply for underground filling work will reduce the production of the underground mines. It is also assumed that in future non-availability of sand is big factor for underground filling work. In future all mines will be an underground mines due to lack of land for stacking of overburden material of open cast as well as it will create environmental and pollution issues with respect to nearby villages, farmers etc.
Therefore, there is a need exists in the art is to provide an alternative which can be used as a filling material for the purpose of hydraulic stowing in an underground mine and solves the issue related to sand such as lease, royalty, transportation, excavation, handling and also solves the issue related to DGMS (Directorate General of Mines Safety), Pollution Control Board etc.
The solution to the problem provided by the present invention is a filling material containing overburden material (hereinafter “OB”) which is commonly available in all type of mining sector.
It is known that OB material contains mica schist, meta-sedimentary rock, calcite, sand stone and dolomite. Most of the OB material is having the characteristics of plastic type paste formation and sudden fragmentation rock particle connection with water. Overburden material is erodible with respect to water, air and temperature.
OBJECT OF THE INVENTION:
It is an objective of the invention is to overcome the aforesaid problems and is to meet the aforesaid needs.
It is an objective of the invention is to provide a composition which can be useful as an alternative filling material for hydraulic stowing process in an underground mine.
It is yet another objective of the invention is to provide a filling material which includes OB material.
It is yet another objective of the invention is to provide a filling material for use in developing sustainable environment.
It is yet another objective of the invention is to provide a filling material for use in regeneration of land for plantation work.
It is yet another objective of the invention is to provide a filling material which is easily available and ready to use for mining purpose.
It is another objective of the invention is to provide a cost-effective filling material for mining purpose.
It is further objective of the invention is to provide a process for preparing the filling material.
SUMMARY OF THE INVENTION:
According to one aspect of the invention, there is provided a composition useful as an alternative filling material for hydraulic stowing process in an underground mine, said composition comprising
I) course overburden material of 2-10mm in the amount of 35% by weight;
ii) fine overburden material of less than 2mm in the amount of 35% by weight;
iii) sand of less than 15mm in the amount of 20% by weight;
iv) gypsum based putty in the amount of 10% by weight;
wherein the composition is treated with a heat at 300°C for 4 hours.
According to another aspect of the invention, there is provided a process for preparing the composition as claimed in claim 1 comprising the steps of:
i) collecting the materials;
ii) mixing the materials to form a homogeneous mixture; and
iii) treating the mixture as obtained in step (ii) with a heat at 300°C for 4
hours.
In accordance with these and other objects which will become apparent hereinafter, the instant invention will now be described with particular reference to the accompanying drawing.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 is the photograph of laboratory test of the developed filling material (product 1,2,3,4 & 5) wherein a); product 4 and b) product 5 before the heat treatment at 300°C; c) product 1-5 after the heat treatment (at 300°C) in accordance with the present invention;
Figure 2 is the photograph of a) plastic product b) non-plastic product in accordance with the present invention;
Figure 3 is the photograph of the water absorption studies of product 1-5 in which a) mix proportion for water treatment; b) 4 hours water absorption study of the product 1-5 in accordance with the present invention; and
Figure 4 is the photograph of field trial (Product 5) in accordance with the present invention.
Other objects, features and advantages of the inventions will be apparent from the following detailed description in conjunction with the accompanying drawings of the inventions.
DETAILED DESCRIPTION OF THE INVENTION:
Definition:
Hydraulic stowing process means to fill the waste in mines by waterborne material by pipeline.
The present invention provides a composition which can be useful as an alternative filling material for hydraulic stowing process in an underground mine, said composition comprises
i. OB materials;
ii. river sand;
iii. clayey soil;
iv. gypsum based synthetic putty;
v. Water

i. OB materials:
It is known that OB material contains mica schist, meta-sedimentary rock, calcite, sand stone, dolomite etc. Most of the OB material is having the characteristics of plastic type paste formation and sudden fragmentation rock particle connection with water. Overburden material is erodible with respect to water, air and temperature.
According to present invention course OB material and fine OB materials are used in the composition. The particle size of course OB material and fine OB material according to present invention is 10mm and less than 2mm respectively. In a preferred embodiment of invention, the size of course OB material is 2.1-10mm.
The concentration of course OB material according to present invention is 30-45% by weight of the total composition.
The concentration of fine OB material according to present invention is 30-45% by weight of the total composition.
ii. River sand:
River Sand generally composed of rounded particles, and may or may not contain clay or other impurities. It is obtained from the banks and beds of rivers.
According to present invention, river sand is one of the component of the present composition.
In preferred embodiment, the size of the sand is less than 15mm.
The concentration of the sand according to present invention is 20% by weight of the total composition
iii. clayey soil:
Clayey soil is a soil that contains a high percentage of fine particles and colloidal substance and becomes sticky when wet.
The concentration of the clayey soil according to present invention is 10-20% by weight of the total composition
iv. Gypsum based Putty:
It is suitable for a wide range of non-structural filling, leveling, patching and/or repair jobs on gypsum boards as well as concrete and fiber cement boards.
The concentration of gypsum based putty according to present invention is 10% by weight.
v. Potable water is used in the amount of 8-10% as water in the present composition.
The aforesaid components are commonly available.
The invention is now illustrated by the way of non-limiting examples:
Example 1:
Applied Methodology
1. Collection of overburden material from various places of Mines and overburden sieved as given below, following material collected for various trials and testing purpose

a. Course Overburden material (size 2 to 10 mm) contain mica schist, meta-sedimentary type of rock formation, intrusion of calcite, sand stone, dolomite, etc.
b. Fine Overburden of above ‘a’
c. River sand (size< 15 mm)
d. Soil having clayey properties
e. Putty (Maximum content of Gypsum)
f. Potable water

Table 1: Composition of filling material
Product Fine OB (< 2 mm) Course OB ( 2.1 to 10 mm) Sand
(< 15 mm) Clayey soil Gypsum based Putty Water Content
1 30% 30% 20% 10% 10% 10%
2 40% 40% NIL 10% 10% 10%
3 35% 35% NIL 20% 10% 10%
4 45 % 45 % NIL NIL 10 % 9 %
5 35 % 35 % 20 % NIL 10 % 8 %

The above product 1 to 5 has been mixed and prepared homogeneous type of mixture. Same mixture has been dried into natural environment to obtain dry surface condition. The dry product mix reduces the water contains and have easy for transportation and obtain pellets/pills in separated forms.

Heat Treatment (HT):

The developed product 1-5 (which is called as “naturally dried”) has been tried first at Munsar mine (Nagpur, Maharashtra) for hydraulic stowing but it was observed that the naturally dried products 1-5 disintegrate easily upon use therefore can’t be allowed for mining purpose. Hence, it was decided to go for the heat treatment (of product 1-5) for the desired results. Accordingly, in house developed kiln has been used for the heat treatment of product no.1- 5 up to 4 hours and the results as observed are hereinbelow:

Table 2: Different heating temperature on prepared product
Temperature in Degree Celsius Product No. Dry weight (gms) Weight after 4 hours immersion in to water Remark
110- 120 1 100 114 Plastic mix produced, impermeable and cohesive in nature
2 100 113 Plastic mix produced, impermeable and cohesive in nature
3 100 140 Plastic mix produced, low permeable type and cohesive in nature
4 100 118 Non-Plastic mix produced, medium permeable and non-cohesive in nature
5 100 120 Non-Plastic mix produced, permeable and non-cohesive in nature,
200 1 100 138 Plastic mix produced, impermeable and cohesive in nature
2 100 130 Plastic mix produced, impermeable and cohesive in nature
3 100 142 Plastic mix produced, low permeable type and cohesive in nature
4 100 125 Non-Plastic mix produced, medium permeable and non-cohesive in nature
5 100 128 Non-Plastic mix produced, permeable and non-cohesive in nature,
300 1 100 128 Plastic mix produced, impermeable and cohesive in nature but low water absorption as compare to above two temperature effect
2 100 124 Plastic mix produced, slightly permeable and cohesive in nature but low water absorption as compare to above two temperature effect
3 100 126 Plastic mix produced, low slightly permeable type and cohesive in nature but low water absorption as compare to above two temperature effect
4 100 128 Non-Plastic mix produced, medium permeable and non-cohesive in nature and complete stable type formation
5 100 127 Non-Plastic mix produced, permeable and non-cohesive in nature, highly water drain out from the mix and stirred product easily settle down.

Figure 1 shows the laboratory test of the developed filling material before and after the heat treatment (300°C) wherein product 4 and product 5 before the heat treatment (Fig. 1a & 1b) and product 1-5 after the heat treatment (Fig. 1c).
Fig. 2a and 2b shows the image of plastic (1,2 & 3) and non-plastic product (4 and 5) respectively.
Specific gravity:
Specific gravity is the ratio of the density of a substance to the density of reference substances, equivalently. It is the ratio of the mass of a substance to the masses of the reference substance for the same given volume. Means material shows it’s flowing capacity into air, water with respect to weight.

W1 - Weight Empty flask in gms
W2 - Weight of empty flak + wt. of product
W3 - Weight of empty flak + wt. of product + Kerosene
W4 - Weight of empty flak + Kerosene

Sg = ( W2-W1)/ [(W2-W1) -(W3-W4) x 0.79] gm/cc

• Course Over burden ( 2- 10 ) mm

W1 - Weight Empty flask in gms = 28 gms
W2 - Weight of empty flak + wt. of product = 153 gms
W3 - Weight of empty flak + wt. of product + Kerosene= 227 gms
W4 - Weight of empty flak + Kerosene = 142 gms

Specific Gravity, Sg = 2.16gm/cc

• Fine Over burden < 2 mm ( White)

W1 - Weight Empty flask in gms = 28 gms
W2 - Weight of empty flak + wt. of product = 135 gms
W3 - Weight of empty flak + wt. of product + Kerosene= 217 gms
W4 - Weight of empty flak + Kerosene = 142 gms

Specific Gravity, Sg = 2.24gm/c
• Fine Over burden < 2 mm ( Gray)

W1 - Weight Empty flask in gms = 28 gms
W2 - Weight of empty flak + wt. of product = 123 gms
W3 - Weight of empty flak + wt. of product + Kerosene= 211 gms
W4 - Weight of empty flak + Kerosene = 142 gms

Specific Gravity, Sg = 2.34 gm/cc

Table 3: The Geo-technical properties of Product 1-5
Mix No Specific gravity HT sample (gm/cc) Dry unit Weight (gm/cc) Bulk density ( gm /cc) Void ratio in dry state) (%) Porosity (%) Permeability of material after HT (m/s) Water retention (cc/ml)
1 2.18 2.10 2.18 46 31.50 0.000005 1.63
2 2.15 1.98 2.13 42 29.57 0.000004 1.95
3 2.12 1.85 2.10 42 29.57 0.000038 1.83
4 2.26 2.24 2.26 35 25.92 0.000038 1.58
5 2.32 2.29 2.34 32 24.24 0.000050 1.58
Figure 3 is the photograph of the water absorption studies of product 1-5 in which Fig. 3a is mix proportion for water treatment; Fig. 3b is 4 hours water absorption study of the heated product 1-5 (at 300°C).
RESULTS & CONCLUSIONS:
The present inventors found that:
• The product mixes of 1,2,3,4 & 5 after treated up to 300°C are suitable for underground hydraulic stowing purpose in underground mines.
• The product 1,2 & 3 are rejected due to it’s non-compatibility and properties are not matching with sand.
• It is also concluded as the increase in temperature will cause the change in bond of the mix means montemorolite converted into illite form, it shows the form of hardness means reducing the internal bond of mica, clay, putty. Putty create the external hydroscopic film on overburden mix and increase in temperature will increase in bond between putty means gypsum and overburden material. Same as putty work as binding the course overburden and to avoid the fragmentation of course size which will converted into fines and fines will act as complete silty product to work as lubricating agent for to avoid the chocking of pipes and filling the gaps of filled material.
• Product 4 and 5 are having the equivalent properties matching with sand as filling material only. It may kindly be noted that this product mix is prepared only for use of fill material in underground mines.
• It is also concludes that the product 4 have low form of settlement and some plasticity and product 5 (inventive product) completely gives very easy drain out of water from the

On the observed results, permeability of product 4 & 5 found to be equally matched with the property of natural silty sand and suitable for hydraulic stowing purpose in underground mines. Product 5 gives more permeability than the other products due to inclusion 20% of sand.

The final field trial (Fig. 4) has been conducted at Munsar Mine (Nagpur, Maharashtra) in underground for quantity of around 30 Cu.m. of the developed product material (product 5) to confirm the physical properties of hydraulic fill in underground for the industrial application in MOIL mines and the findings are:
• the retaining capacity is more than the sand;
• compact fill have more in built compressive and tensile than sand floor;
• min expansion of bed with higher load;
• floor is easy for movement of men & machines;
• old refuse material can be utilized for hydraulic transportation in underground.

Although the foregoing description of the present invention has been shown and described with reference to particular embodiments and applications thereof, it has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the particular embodiments and applications disclosed. It will be apparent to those having ordinary skill in the art that a number of changes, modifications, variations, or alterations to the invention as described herein may be made, none of which depart from the spirit or scope of the present invention. The particular embodiments and applications were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such changes, modifications, variations, and alterations should therefore be seen as being within the scope of the present invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.