US3692364A

US3692364A - Method of open-pit mining

Info

Publication number: US3692364A
Application number: US84963A
Authority: US
Inventors: Sune Torsten Henriksson; Ragnar Ludvig Muotka
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-10-31
Filing date: 1970-10-29
Publication date: 1972-09-19
Anticipated expiration: 1989-09-19
Also published as: PL81151B1; CA972386A; SE330519C; SE330519B; CS214848B2; ZM11970A1; ZA707338B; FR2066713A5; ES385026A1

Abstract

A method of open-pit mining according to which a transport ramp system is provided in a tunnel system outside the open pit and the body of materials which is mined for establishing communication between the surface and the different mining levels.

Description

United States Patent Henriksson et a1.

METHOD OF OPEN-PIT MINING Inventors: Sune Torsten Henrikson, Kvartsvagen 6; Ragnar Ludvig Muotka, Kyrkogatan 46, both of 981 00 Kimna, Sweden Filed: Oct. 29, 1970 App1.No.: 84,963

Foreign Application Priority Data Oct. 31, 1969 Sweden ..l4945/69 US. Cl ..299/l8, 299/19 Int. Cl ..E21c 41/00 Field of Search ..299/18, 19; 37/195; 61/5,

[4 Sept. 19, 1972 t [56.] References Cited UNITED STATES PATENTS 3,167,354 1/1965 Macaul et a1. ..299/l8 X 3,582,138 6/1971 Loofbourow et a1. ..299/l8 Primary Examiner-Emest Purser Attorney-Jones & Lockwood [57] ABSTRACT A method of open-pit mining according to which a transport ramp system is provided in a tunnel system outside the open pit and the body of materials which is mined for establishing communication between the surface and the different mining levels.

6 Claims, 6 Drawing Figures mg n! SmEmgnl g PATENTEB 19 I912 3.692.364

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METHOD OF OPEN-PIT MINING The present invention relates to mining and, in particular, to a method of open-pit mining.

In an open-pit mine which is used when the deposit of ore or minerals to be mined starts from or lies adjacent to the surface of the ground it is known to establish communications between the working site or the mining level in question and the surface by means of a transport track or ramp which extends from the surface downwardly along the walls of the open-pit mine which are formed accordingly as the mining progresses. For each new mining level a new transport ramp must be established, and ore or other materials which are mined must be carried away. Also the material surrounding the ore or mineral body which is mined must be removed. in that connection such a quantity of the surrounding material must be removed that the slope stability required in each particular case is obtained in the walls of the open-pit mine and that the necessary space is obtained for the inclined track or ramp extending along said walls. As the transport ramp must have a width of to 13 meters including the requisite protective wall at the outer side of the ramp, the building of the transport ramp entails a substantial increase of the quantity of materials which have to be removed, in addition to the quantity of materials required in order to obtain the necessary slope stability. It will therefore be realized that the quantity of materials which increases in proportion to the distance of the transport ramp from the surface of the ground must be carried away when a length unit of the ramp is built since for obtaining each surface unit of the transport ramp it is necessary to remove a volume .of materials corresponding to the surface unit in question multiplied by its distance to the surface of the ground. In an openpit mine of a great depth the building of the inclined track or ramp will consequently entail considerable building costs.

Not only the building costs but also the maintenance costs are however very high when using transport ramps of the known kind described above. Thus, for safety reasons it is necessary to clear the rock wall above the transport ramp, which cannot be done once only when the ramp is built but has to be performed at even time intervals due to the fact that the rock wall will weather under the action of the climate. Since the surfaces to be cleared are very large and the work is risky and time consuming especially when there is ice and snow the costs in this connection are substantial.

When the road is very slippery and when great amounts of snow and rain have fallen it may become necessary to interrupt traffic on the transport ramp completely which, as will be realized, makes it necessary to stop the mining after a short time. Such a total stop may entail losses amounting to tens of thousands of dollars per hour. In tropical countries the stop may have to be total for several weeks during the rains, when it may also happen that the transport ramp is completely destroyed.

There is an additional problem in connection with snowfall, as the snow must be conveyed down to the bottom of the pit, where it has to be loaded onto trucks and then carried up to the surface. It will-be realized that this complicated method of removing snow from the transport ramps and roads is very expensive.

The object of the invention is consequently to provide a method of open-pit mining in which the establishing of communications between various mining levels and the surface of the ground is more inexpensive both with regard to the building costs and with regard to the maintenance costs thanin connection with the known methods of mining.

This object is attained according to the invention by building the transport tracks or ramps in tunnels in the mountain outside the body of materials which is mined.

The building costs for an inclined track or a ramp built in a tunnel are considerably lower than for a ramp built in open air in a conventional manner. It is true that the costs per unit of volume of removed'materials will be slightly higher when the ramp or track is built in a tunnel but these increased costs are more than compensated for by the fact that a very much smaller volume of materials has to be removed per built surface unit of the inclined track or ramp when the latter is built in a tunnel. Evidently, there is required for each surface unit of the ramp a constant volume of removed materials independently of the distance of the ramp from the surface, and the costs saved when applying the method according to the invention will consequently become proportionally higher accordingly as the depth of the open-pit-mine increases. Thus, for instance, for an open pit having a depth of 500 meters the costs for building an inclined track in the manner according to the invention have been assessed to amount to only 2.8 per cent of the costs for building a conventional transport ramp in the open air.

As also the maintenance costs of a transport track or ramp built in a tunnel'will for obvious reasons beconsiderably lower than with respect to a conventional 'rampit will be realized that the savings which can be made when applying the mining method according to the invention are considerable. No cleaning of large surfaces is required and besides,the risks of slipping when there is ice and snow as well as the interruptions of the operation due to the action of the climate are completely eliminated.

The position of the transport ramp must be determined from case to case in view of the shape of the body of materials which is mined, the type of materials in the body and the materials surrounding it, etc. Thus, the transport ramp may extend around the body of materials or may be located serpentine-like on one side thereof.

Connections are built between the ramp and the working sites on the different levels, and these connections are planned according to the same principles as in a ramp system built in open air.

The invention will be described in greater detail in the following with reference to the accompanying drawings, where FIGS. la and 1b are diagrammatic views of a manner of arranging a transport ramp according to the invention,

FIGS. 2a and 2b are also diagrammatic views of another manner of arranging a transport ramp according to the invention,

FIG. 3 shows a way of arranging the connection between the inclined track and the surface of the ground, and

FIG. 4 shows another manner of arranging the connection of the inclined track with the surface of the ground.

FIGS. 'la and lb are diagrammatic views of an ore body 1 which is to be mined according to the open-pit mining method. In order to obtain the necessary slope stability the surrounding rock 2 must be removed along the lines 3 and 4 accordingly as the mining progresses. Communications with the mining levels which will be located at longer and longer distances from the surface of the ground is obtained by means of a transport ramp or an inclined track 5 built in a tunnel which extends serpentine-like at the righthand side of the ore body in the figure, i.e., on the so called foot wall side of the ore body, and by means of horizontal tunnels 6 extending from the transport ramp to the working sites. When building the tunnels it is possible, if necessary, to reinforce the tunnel walls by means of rock bolts and the like, whereupon the communication system may be regarded as almost maintenance-free. The only kind of maintenance which is normally required is consequently the maintenance of the transport ramp, which is worn by the vehicle traffic.

FIGS. 2a and 2b show another ore body 7. In this case it has been considered suitable to let the transport ramp 8 extend in a tunnel running helically around the ore body. In this case, too, communication is established between the ramp and the working sites by means of horizontal tunnels 9. The rock surrounding the ore body is removed in the ordinary manner along the lines 10 and 11 in order to achieve the requisite slope stability.

FIG. 3 shows the embodiment of a connection between a ramp 12 built in the tunnel and the surface of the ground. As appears from the figure, the tunnel and consequently the ramp has a section 13 at the orifice which is inclined outwardly downwardly with an angle of inclination in relation to the horizontal plane which preferably amounts to 1 to 3. The purpose of giving the top section of the ramp an inclination which is opposite to the rest of the transport ramp in relation to the horizontal plane is of course to prevent rain and snow from entering the communication system and cause difficulties of various kinds there. Since the tunnel in the case shown opens into an inclined portion of the surface of the ground a roof or cover above the top section of the transport ramp is automatically obtained.

FIG. 4 shows how the tunnel opens at a plane part of the surface of the ground and in this case it is necessary to build a special superstructure 14 in order to cover the opening of the tunnel.

It will be realized that the invention can be modified within the scope of the following claims, and particularly with regard to the extension of the inclined track and consequently of the tunnel system in relation to the body of materials where the mining takes place the application of the invention must be determined from case to case.

We claim:

1. A method for transporting ore upwardly from a deep open-pit mine to the ground surface, which method comprises the steps of:

a. forming a downwardly inclined tunnel system from the ground surface and extending the tunnel s st d nwardl throu h the ater'als 'n oirts i ia ofihe open pit min parts 0 sai out yin tunnel system being formed in communication with the open-pit mine; v

b. providing an inclined transport ramp system throughout said tunnel system;

c. transporting ore on said ramp system from the open-pit mine and through the tunnel formed in the materials lying outside of the open-pit mine; and

d. recovering the ore at the ground surface.

2. The open-pit mining method of claim 1 which the outlying tunnel system is formed helically around the open-pit mine.

3. The open-pit mining method of claim 1 in which the tunnel system is formed serpentine-like at one side of the open-pit mine.

4. The open-pit mining method of claim 1 in which substantially horizontal tunnels are provided in communication between the downwardly inclined tunnel system and the open-pit mine.

5. The open-pit mining method of claim 1 in which the transport ramp system is provided with an outwardly-downwardly sloping ramp section at the junction of the. ramp system and the ground surface.

6. The open-pit mining method of claim 1 in which the downwardly inclined tunnel system is provided with a superstructure at the junction of the tunnel system and the ground surface.

I ii

Claims

1. A method for transporting ore upwardly from a deep open-pit mine to the ground surface, which method comprises the steps of: a. forming a downwardly inclined tunnel system from the ground surface and extending the tunnel system downwardly through the materials lying outside of the open-pit mine, parts of said outlying tunnel system being formed in communication with the open-pit mine; b. providing an inclined transport ramp system throughout said tunnel system; c. transporting ore on said ramp system from the open-pit mine and through the tunnel formed in the materials lying outside of the open-pit mine; and d. recovering the ore at the ground surface.

5. The open-pit mining method of claim 1 in which the transport ramp system is provided with an outwardly-downwardly sloping ramp section at the junction of the ramp system and the ground surface.