MT20: STOPPING METHODS ITS CLASSIFICATION AND FACTORS AFFECTING.

Stope: It is a solid are block or ore pillar which is under extraction is called stope.

Stoping: It is the method of extraction of ore from a block or pillar formed during development. As a rule stopping is started on each side of a raise winze connection.

Stoping Method: Stoping is the final extraction of an ore body that has already been developed. The main work consists of drilling & blasting or ore. Removal of the broken ore from working place & supporting the ground, so that the operation can be carried out safely varies methods of stopping are adopted have been adjective to exploit the ore in the sagest & economical way observing the rule of conservation of minerals.

 

CLASSIFICATION OF STOPING METHODS :

(A) Stopes naturally supported.

 (1) Open stopping.

     (a) Open stopes in small ore bodies.

     (b) Sublevel stopping.

     (c) Long hole stopping.

(2) Open stopes with pillar supports.

    (a) Casual pillars.

    (b) Room (or stope) and pillar (regular arrangement)

(B) Stopes artificially supported.

(3) Shrinkage stopping.

   (a) With pillars.

   (b) Without pillars.

   (c) With subsequent waste filling.

(4) Cut and fill stopping.

(5) Stulled stopes in narrow veins.

(6) Square-set stopping.

(C) Caved stopes.

(7) Caving (ore broken by induced collapse)

   (a) Block caving : including caving to main levels and caving to chutes or brached raises.

   (b) Sublevel caving.

(8) top slicing (working under a mat, which together with caved overburden follows the mining  downward in successive stages)    

 

(D) Combination of supported and caved stopes, (as shrinkage stopping with pillar caving, cut and fill stopping and top slicing of pillars, etc.)

 

APPLICATION OF UNDERGROUND METAL MINING METHODS.

Type of ore body	Dip	Strength of ore	Strength of walls	Possible Method of Mining
Thin bodies.	Flat	Strong	Strong	Room and pillar, casual pillar, Open stopes.
		Weak or strong	Weak	Top slicing, Longwall
Thick bodies.	Flat	Strong	Strong	Sub-level stopping, Room and pillar, Cut and fill
		Weak or strong	Weak	Sub-level caving, Top slicing
		Weak	Strong	Square set, Cut and fill, Sub-level stopping.
Narrow veins.	Steep	Weak or strong	Weak or strong	Resuing in (a) Open stopes or, (b) Stulled stopes
Thick veins.	Steep	Strong	Strong	Open stopes, Sub-level stopping, Shrinkage stope, Cut and fill method.
	Steep	Strong	Weak	Cut and fill stopes, Square set stope,Top slicing, Sub-level caving
	Steep	Weak	Strong	Open casual pillar, Square-set stope,Top slicing, Block caving, Sub level caving
	Steep	Weak	Weak	Square-set stopes, Top-slicing, sub-level caving
Massive		Strong	Strong	Shrinkage stope, Sub-level stopping, Cut and fill stope
		Weak	Weak or strong	Square-set stope,Top-slicing, Sub-level caving, Block caving

FACTORS AFFECTING STOPING METHODS :

1. Thickness of ore body: There are ore bodies which are thin, thick and extra ore bodies. Thin ore bodies are suitable to work with breast-stoping method.
2. Dip of the ore body: The ore bodies with low inclination and not extending 35° inclination are suitable for breast stoping method.
3. Character of ore bodies: Some of the ore bodies are strong and some of the ore bodies are weak.
4. Character of walls: Some cases the hanging wall or footwall of ore bodies are strong and in some cases either the hanging wall or footwall or both may be weak.
5. Cost of ore bodies: Some of  the ore bodies contain, costly minerals and some of the ore bodies costly due to rich mineralization.
6. Nature of Mineralization of ore body: The ore body contain low percentage of mineral can be worked by breast stoping method.
7. Continuity of ore body: Some of the ore bodies are continuous and regular ore bodies are worked by timer stopped method and shrinkage stopping method.
8. Cost of supports and availability: In case of timber stope method and top slicing method regular supply is supplied.
9. Depth of the ore body from surface: When ore bodies are at shallow depth the harrying bore method can be used.
10. The shape, size and regularity of the deposit.
11. Mineralogical character and value of ore and the distribution of values.
12. The dip, width and strength of the ore.
13. Nature of overburden.
14. Possibility of dilution of ore with waste.