CA2010882C

CA2010882C - Stabilization of cemented back fill areas for mines

Info

Publication number: CA2010882C
Application number: CA 2010882
Authority: CA
Inventors: John Patrick Sheridan
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-02-26
Filing date: 1990-02-26
Publication date: 2001-05-29
Anticipated expiration: 2010-02-26
Also published as: CA2010882A1

Abstract

This invention provides a method of stabilizing cemented back fill areas for mines. After certain mining operations have been carried out, creating mined voids, it is common to back fill for purposes of stabilizing the rock conditions in the areas where the mining operations have taken place. Generally, the back filling comprises "cementing" which is in fact placing concrete made using the coarse broken rock fraction from the mine tailings. The concrete is pumped or dumped or otherwise put into place, usually without any use of reinforcing steel bars or other reinforcement. By the present invention, additional very large aggregate pieces are placed in the back fill area at the same time as the concrete is pumped or dumped into that area. Those additional very large aggregate pieces are generally at least portions of used automotive tires, or they may be whole tires or shredded tires, or other large pieces of waste rubber material.
It has been determined that the use of such very large aggregate pieces in cemented back fill increases the stabilization of the back fill, thereby assuring stabilization of rock conditions in the mined area where the back fill has been placed.

Description

STABILIZATION OF CEMENTED BACK FILL AREAS FOR MINES
FIELD OF THE INVENTION:
This invention relates to the stabilization of cemented back fill areas for mines, particularly where back fill areas are generally filled with concrete that has been made from the coarse aggregate fraction of mine tailings. The present invention provides for the additional use of very large aggregate pieces that are put into place at the same time as the concrete is placed in the back fill area; and the present invention contemplates further that the very large aggregate pieces may be whole used automotive tires, or at least large pieces or shredded tires, or other waste rubber material.
BACKGROUND OF THE INVENTION:
It is sometimes desirable for a mined area to be back filled when the mining operation has concluded in a particular location, for purposes of stabilizing the rock conditions in that area. Thus, after a mined void has been determined that there will no longer be any further mining operations in that immediate area, the mined void may be back filled so as to stabilize the rock conditions in that area. This may be because of other mining operations being carried out in adjacent or nearby locations, or to stabilize the area against possible collapse of overburden, and so on.
Normally the concrete that is used for such cemented back fill operations is made using aggregate which is the coarse fraction of mined tailings taken from the mine. That coarse fraction may have come as a result of initial crushing of the material being taken out from the mine, or the removal of overburden before the ore-bearing lode is encountered, and so on. In any event, the aggregate may exist and can be used.
It has been determined, however, that it may be helpful to use very large aggregate pieces in the backfill, which very large aggregate pieces may not be rock chunks but may be man-made debris which is otherwise to be disposed of. Particularly, that man-made debris may be used automotive tires, or pieces or shredded tires, and the like.
It has long been recognized that any mode of disposal of used automotive tires other than placing them in dumps or landfill areas that may be particularly intended for collected used automotive tires, is desirable. Not only are the dumps of used automotive tires unsightly, they have been found to create environmental hazards. For example, a recent fire of some 12 million tires at Hagersville, Ontario has caused the creation of liquid hydrocarbons as the tires have melted; those liquid hydrocarbons are essentially crude oil and may have high toluene or benzene contents.
It has been estimated that, in North America, used automotive tires are created at the rate of one used tire per person per year. That means that, in North America (Canada and the United States) nearly 300 million tires per year may be required to be disposed of.
The present invention provides a means of disposing of at least a portion of those unwanted used automotive tires. Unexpectedly, it has been found that by placing the used automotive tires in concreted mind back fill projects, at the same time as the concrete is being placed in the mined void area, substantial numbers of used automotive tires may be disposed of.
BRIEF DESCRIPTION OF THE DRAWINGS:
The novel features which are believed to be characteristic of the present invention, as to its structure, organization, use and method of operation, together with further objectives and advantages thereof, will be better understood from the following drawings in which a presently preferred embodiment of the invention will now be illustrated by way of example. It is expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. Embodiments of this invention will now be described by way of example in association with the accompanying drawings in which:
Figure 1 illustrates the general principles of the present invention, showing a cemented back fill area in a mine.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:
What the present invention provides, therefore, is a method of stabilization of cemented back fill areas for mines, where the cemented back fill is placed in mined void areas for purposes of stabilizing rock conditions in those areas, and the method comprises the steps of:
(a) mixing a sufficient quantity of concrete for the cemented back fill operation to substantially take up a predetermined volume in the mined void area to be back filled.
That means that the volume of the shaft or chamber to be back filled is more or less determined, and a quantity of concrete somewhat less than the determined volume is prepared. Then, the following steps are carried out:
(b) the concrete is placed in the mined void area to be back filled; and (c) at the same time as step (b) is being carried out, additional very large aggregate pieces are introduced into the concrete as it is being placed. The very large aggregate pieces are immensely larger than any aggregate that has been used in the mixture of the concrete.
Usually, the concrete is pumped or dumped into place, and that generally means that it should not have large pieces of aggregate in it. Otherwise, very special purpose equipment for handling the concrete may be required.
As it happens, however, by following the present invention and placing automotive tires or pieces or shredded automotive tires, or other large pieces of waste rubber material such as broken belting from ore-handling facilities and the like, not only may the cemented back fill operation proceed more quickly, but it may be accomplished less expensively than previously.
It has been determined that the cemented back fill having the used automotive tires placed in it, in keeping with the present invention as very large aggregate, sets up more quickly and provides for a very stable back fill mass. Because of the presence of the very large aggregate pieces in the cemented back fill, it is not as homogenous as it otherwise would have been, so it may be less likely to fail under certain shear conditions.
Referring now to Figure l, a representation is made of a cemented mine back fill project. Here, a cemented back fill 12 is placed in a mine gallery or tunnel 14, which is accessed by a mine shaft 16. As described, the area where the concrete for the back fill 12 is placed is a mined void area, and the cemented back fill is placed for purposes of stabilization of the mined void area and its surroundings.
The cemented back fill 12 comprises ordinary concrete 18, having the usual pebble aggregate 20 found throughout the concrete. However, additional very large aggregate pieces 22 are also found in the concrete back fill 12, and those very large aggregate pieces 22 are at least portions of used automotive tires, or other large pieces of waste rubber material as noted above.
By following the present invention, not only is there a partial solution to the problem of disposition of used automotive tires presented, but the required back fill operation may be accomplished less expensively and more quickly than previously, with superior rock stabilization properties. The scope of the present invention is defined by the appended claims.

Claims

1. A method of stabilization of cemented back fill areas for mines, where the cemented back fill is placed in mined void areas for purposes of stabilizing rock conditions in those areas, comprising the steps of:
(a) making a sufficient quantity of concrete for the cemented back fill operation to substantially take up a pre-determined volume in the mined void area to be back filled, wherein said concrete includes concrete aggregate;
(b) placing said concrete in the mined void area; and (c) at the same time as step (b) is being carried out introducing into the concrete as it is being placed additional very large aggregate pieces, where the very large aggregate pieces are immensely larger than the concrete aggregate used in said concrete, and wherein said very large aggregate pieces are any of the group consisting of whole used automotive tires, portions of used automotive tires, shredded used automotive tires, and other large pieces of waste rubber material.

2. The method of Claim 1, wherein said very large aggregate pieces are at least portions of used automotive tires.