CA2539268C - Thermal rock fragmentation application in narrow vein extraction - Google Patents
Thermal rock fragmentation application in narrow vein extraction Download PDFInfo
- Publication number
- CA2539268C CA2539268C CA2539268A CA2539268A CA2539268C CA 2539268 C CA2539268 C CA 2539268C CA 2539268 A CA2539268 A CA 2539268A CA 2539268 A CA2539268 A CA 2539268A CA 2539268 C CA2539268 C CA 2539268C
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- Prior art keywords
- vein
- ore
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- hole
- holes
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- 210000003462 vein Anatomy 0.000 title claims abstract description 77
- 239000011435 rock Substances 0.000 title claims abstract description 15
- 238000013467 fragmentation Methods 0.000 title claims description 23
- 238000006062 fragmentation reaction Methods 0.000 title claims description 23
- 238000000605 extraction Methods 0.000 title description 10
- 238000000034 method Methods 0.000 claims abstract description 29
- 239000012634 fragment Substances 0.000 claims abstract description 10
- 238000005553 drilling Methods 0.000 claims description 4
- 229910052500 inorganic mineral Inorganic materials 0.000 abstract description 9
- 239000011707 mineral Substances 0.000 abstract description 9
- 238000005065 mining Methods 0.000 description 24
- 239000000463 material Substances 0.000 description 14
- 239000010878 waste rock Substances 0.000 description 8
- 238000010790 dilution Methods 0.000 description 7
- 239000012895 dilution Substances 0.000 description 7
- 230000005465 channeling Effects 0.000 description 5
- 230000033558 biomineral tissue development Effects 0.000 description 4
- 239000002360 explosive Substances 0.000 description 3
- 238000009412 basement excavation Methods 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 239000008186 active pharmaceutical agent Substances 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005422 blasting Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 239000002283 diesel fuel Substances 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000004901 spalling Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21C—MINING OR QUARRYING
- E21C37/00—Other methods or devices for dislodging with or without loading
- E21C37/16—Other methods or devices for dislodging with or without loading by fire-setting or by similar methods based on a heat effect
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21C—MINING OR QUARRYING
- E21C25/00—Cutting machines, i.e. for making slits approximately parallel or perpendicular to the seam
- E21C25/58—Machines slitting by drilling hole on hole
Landscapes
- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Mechanical Engineering (AREA)
- Drilling And Exploitation, And Mining Machines And Methods (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
A free-blast method for extracting ore from an ore vein deposit (12) wherein the vein is extracted by causing the ore comprised between the rock walls (16) bordering the vein (12) to spall into fragments. The ore fragments are recuperated as by aspiration and subsequently processed to retrieve the precious mineral.
Description
THERMAL ROCK FRAGMENTATION API'LIC: ATION
IN NARROW VEIN EXTRACTION
BACKGROUND OF TIIE INVENTION
Field of the Invention The present invention relates to ore extraction and, nosrc particularly, to thermal fragmentation mining for extracting ore from narrow--veins.
Descri~ation of the Prior Art For many years, ursine operators have worked on various wav, to mechanize mining. They have succeeded in many cases where the ore volume was sufficient to justify the high capital costs of equipment and the rccluir~d infrastructures. Narrow-vein deposits, for their part, presented a greater challcn~~e in terms of mechanization. Selective mining methods, such as shrinl<ayae, mre replaced by using a mechanized long-hole mining method. Despite Bill the vflorts put into place, success stories remain rare. The difficulty in controlling wall stability following blast vibrations often resulted in hi<~h dilution, prwenring narrow-veins extraction from being economically viable. Indeed, veins ol~
small cross-section have in the past been uneconomical to mine since with the cur~wnt mining methods a small vein necessitates the removal of a large quantity of waste rock on either sides of the vein. A large quantity of ore must then be proccsaad tc>
retrieve the small quantity of desired minerals.
Therefore, a great number of known narrow veins oC
mineralization are not presently mined since mining of such minerals is not economically viable due to the limitations of the present mining methods.
SUMMARY OF THE INVENTION
It is therefore an aim of the present invention to provide a new ore extracting process for allowing narrow veins of mineralization to be mined profitably.
It is a further aim of the present invention to provide a new and efficient mining approach for extracting ore from narrow-veins.
It is a still further aim of the present invention to optimize ore recuperation.
It is a further aim of the present invention to provide a nwv narrow-vein ore extraction process by which dilution from the walls of the vein is minimal.
Therefore, in accordance with the present invention, there is provided a method for extracting ore from an ore vein deposit, comprisio'~ the steps of a) establishing the location of the rock malls bordering the ore voin deposit, b) causing the ore comprised between the rock walls to spill into fragments, and c) retrieving the fragments.
In accordance with a furd~er general aspect of the hrcscnt invention there is provided a process for extracting ore from a vein liavin~;
opposed sidewalk, comprising the steps of a) drilling pilot holes directly in the vein at specific intervals therealong, b) using thermal fragmentation, enlarging the pilot holes until the vein is fragmented, and c) recuperating the fragmented are along the vein.
In accordance with a fiirther general aspect of the hre~cnt invention, there is provided a free-blast mining method for extractin~~ ore fion~ a vein having opposed sidewalk, comprising the steps of: locating the vein and determining the extent thereof, b) moving the burner at a controlled rate of trawl between the sidewalk of the vein to cause the ore comprised in the vein to span into fragments, and c) retrieving the fragments.
BRIEF DESCRIPTION OF TI-IE DRAWINGS
Having thus generally described the nature of floe invcmion, 25 reference will now be made to the accompanying drawings, showin~~ Lay woe of illustration a preferred embodiment thereof, and in which:
Fig. 1 is a schematic comparison between a long-hole mining method and a thermal fragmentation mining concept in accordance with a preferred embodiment of the present invention;
30 Fig. 2 is a schematic top plan view of an ore vein illustrating how the ore can be recuperated by thermal rock fragmentation;
IN NARROW VEIN EXTRACTION
BACKGROUND OF TIIE INVENTION
Field of the Invention The present invention relates to ore extraction and, nosrc particularly, to thermal fragmentation mining for extracting ore from narrow--veins.
Descri~ation of the Prior Art For many years, ursine operators have worked on various wav, to mechanize mining. They have succeeded in many cases where the ore volume was sufficient to justify the high capital costs of equipment and the rccluir~d infrastructures. Narrow-vein deposits, for their part, presented a greater challcn~~e in terms of mechanization. Selective mining methods, such as shrinl<ayae, mre replaced by using a mechanized long-hole mining method. Despite Bill the vflorts put into place, success stories remain rare. The difficulty in controlling wall stability following blast vibrations often resulted in hi<~h dilution, prwenring narrow-veins extraction from being economically viable. Indeed, veins ol~
small cross-section have in the past been uneconomical to mine since with the cur~wnt mining methods a small vein necessitates the removal of a large quantity of waste rock on either sides of the vein. A large quantity of ore must then be proccsaad tc>
retrieve the small quantity of desired minerals.
Therefore, a great number of known narrow veins oC
mineralization are not presently mined since mining of such minerals is not economically viable due to the limitations of the present mining methods.
SUMMARY OF THE INVENTION
It is therefore an aim of the present invention to provide a new ore extracting process for allowing narrow veins of mineralization to be mined profitably.
It is a further aim of the present invention to provide a new and efficient mining approach for extracting ore from narrow-veins.
It is a still further aim of the present invention to optimize ore recuperation.
It is a further aim of the present invention to provide a nwv narrow-vein ore extraction process by which dilution from the walls of the vein is minimal.
Therefore, in accordance with the present invention, there is provided a method for extracting ore from an ore vein deposit, comprisio'~ the steps of a) establishing the location of the rock malls bordering the ore voin deposit, b) causing the ore comprised between the rock walls to spill into fragments, and c) retrieving the fragments.
In accordance with a furd~er general aspect of the hrcscnt invention there is provided a process for extracting ore from a vein liavin~;
opposed sidewalk, comprising the steps of a) drilling pilot holes directly in the vein at specific intervals therealong, b) using thermal fragmentation, enlarging the pilot holes until the vein is fragmented, and c) recuperating the fragmented are along the vein.
In accordance with a fiirther general aspect of the hre~cnt invention, there is provided a free-blast mining method for extractin~~ ore fion~ a vein having opposed sidewalk, comprising the steps of: locating the vein and determining the extent thereof, b) moving the burner at a controlled rate of trawl between the sidewalk of the vein to cause the ore comprised in the vein to span into fragments, and c) retrieving the fragments.
BRIEF DESCRIPTION OF TI-IE DRAWINGS
Having thus generally described the nature of floe invcmion, 25 reference will now be made to the accompanying drawings, showin~~ Lay woe of illustration a preferred embodiment thereof, and in which:
Fig. 1 is a schematic comparison between a long-hole mining method and a thermal fragmentation mining concept in accordance with a preferred embodiment of the present invention;
30 Fig. 2 is a schematic top plan view of an ore vein illustrating how the ore can be recuperated by thermal rock fragmentation;
Fig. 3 is a schematic elevation view showing a surface excavation design that can be used when the narrow vein is extracted by thermal fragmentation;
Fig. 4 is a schematic perspective view of a narro»- vein in the process of being grooved out by thermal fragmentation in accordance with a further embodiment of the present invention; and Fig. 5 is a schematic side elevation view illustrating a thermal fragmentation channeling operation carried out for extracting ore from a narrow vem.
DESCR1P'1'ION OF 7'HE PREFERRED EMBODINIIi\I'1'S
It is a problem in the field of mining to economically extract hi~~h grade materials, such as gold, platinum, copper or other precious materials, from a narrow vein of mineralization. A narrow vein of mineralization is normally not commercially mined because the return in volume of useable mineral ('or the amount of ore removed and the amount of labor required to remove the ore render it uneconomical to retrieve the desired minerals in a narrow vein application.
~s will be seen hereinafter, the present invention provides a solution to that particular problem by significantly minimizing the dilution of the hrccious mineral into the surrounding waste rock during the extraction operation 20 Unlike conventional mining methods which require that a ;great amount of commercially worthless rock (barren) be removed on either side o('the vein due to the utilization of explosive charges, the present free-blast mining method provides for the removal of the true value only, i.e. the extraction of the mineral deposit from the surrounding environment. 'l:~his rnay be rradilv 25 appreciated from Fig. 1 which shows a schematic comparison between the dilution associated with a conventional mining method and the present thermal fragmentation mining method. More particularly, according to the conventional long-hole mining method, blastholes 10 are drilled in the vein 12 and on either side thereof. Each blasthole 10 is filled with an explosive; charge., such as 30 dynamite, and the region in the vicinity of the blastholes 10 is li~agmentcd by the explosive power of the charge. This results in the formation of a large trench 1=1 which extends laterally outwardly of the vein sidewalk 16 along all the Ien~~th of vein 12. For instance, in the case of a vein having a 30 cm (12 inches) width, a trench of 140 cm (55 inches) in width will have to he blasted. This implies a dilution of about 55 cm (22 inches) on each side of the vein 12 throu~~hovt the 5 length thereof. That is to say that the amount of waste or commercially worthless material that has to be mined is significantly greater than the amount of material comprised between the vein sidewalk 16. Thc; ratio is about G tonnes of commercially worthless matter for 1 tonne of desired mineral.
hi contrast, according to the present invention, pilot holes 18 (not 10 blastholes) are defined directly in the vein 12 and subseduently cnla~-~~ecl or reamed by thermal fragmentation to the vein sidew~ulls 1G, thereby uvoiclin~~
dilution of the ore body contained in the vein in the commercially worthless matter located outwardly of the vein sidewalls l6. 'fhe trench can he kept us narrow as possible. This permits to extract 1 tonne of the desired mineral li>r 2 15 tonnes of gangue.
According to a preferred mode of extraction of the present invention, a first series 20 of three pilot holes 22, 24 and 2G are drilled dirr~tly into the vein 12 at predetermined longitudinal intervals, as shown in Fi'; 2.
Cho intervals are determined by the width of the vein 12. For a vein l~avin~~ a 12 20 inches (30 em) width, the pilot holes are preferably of about 6 inches ( l s cm) in diameter and spaced by a distance of about 21 inches (53 em). >ach pilot hole is between 40 feet (12 m) to 60 feet (18 m) deep and substantially center relative to a central axis of the vein 12. The broken material produced is recuperaicd Baud subsequently processed to separate the mineralized material from the barren.
25 The next step consists in the verification of the pilot holes 2?. ?=1 and 26. hi order to make sure that the pilot holes 22, 24 and 2G are in the vein 12, a conventional in-the-hole device (not shown) is used to locate the vein 12.
Once the ore is located in the pilot holes 22, 24 and 26, thermal fragmentation is started to enlarge each pilot hole to the sidewalk 16 of the vein 12. In practice, it is 30 understood that the pilot holes 22, 24 and 26 might in some instances be tlZermally reamed to a location which is located slightly outwardl~~ o(~ thc:-sidewalk 16 of the vein 12, as shown in dotted lines in Fig. 2. Each pilot hole is enlarged by lowering a strong burner (not shown), powered by diesel fuel and air, into the hole and by igniting it. The burner could also be provided in the form of a plasma torch, especially in underground mining operations. 'fhe heat ~~encratcd by 5 the burner raises the temperature in the hole up to 1800° C. 'this creates tl~ennnl stresses that span the rock. In simple terms, spalling is considered to he a Iurnn of decrepitation caused by an unequal expansion of rock crystals which overcomes molecule cohesion. The broken or fragmented material produced during this process ranges in size from fine grain to 4 cm (1.6 inch).
10 The first three pilot holes 22, 24 and 26 are preferably individually enlarged along all the length thereof from bottom to top in a predetermined sequence starting with the first hole 22, the third hole 26 and the second hole ?-1.
The broken material produced during the thermal fragmentation operation o1' the first and third holes 22 and 26 is preferably left in the holes to act as a thermal 15 barrier for preventing heat from escaping from the second hole 24 v~hen the pillars of material separating the second hole 24 from the first hole 22 and the second hole 24 from the third hole 26 start to become fragmented, thereby allowing heat to pass from the second hole 24 to tlne lust and the third holes ~?
and 26. By leaving the fragmented material in the holes until the thcr~nal 20 fragmentation is fully completed in the adjacent hole, signiticunt saving can be made in tern of thermal energy consumption. As shown in dotted lines in Fi~T.
~, the second hole 24 is enlarged to a greater extent than the first and third holes 22 and 26 so as to completely fragment the pillar between the first and second hc7les 22 and 24 and the pillar between the second and third holes 24 and 26.
25 Thereafter, a second series 28 oh pilot holes, comprisiy Uvo longitudinally spaced-apart holes 30 and 32, are drilled directly in the vein 1'? at the downstream end of the first series 20. The second pilot hole 32 of the second series 28 is first enlarged by thermal fragmentation followed by the first pilot hole 30. As for the first series 20, the fragmented material produced during the thermal 30 fragmentation performed in each hole is preferably left in the hole and the first pilot 30 is euarged to a greater extent than adjacent holes 26 and 32. As a ;~cr~cral rule, the holes which are enlarged to a large size are always comprised between two pairs of pilot holes which have already been enlarged. As represented by reference numeral 34 further pairs of longitudinally spacec-1-apart pilot holes 3G
and 38 are subsequently drilled and enlarged until the end of the vein I? is reached.
Once the vein I2 has been fragmented on all the length tlmmof or along a sufficient portion thereof, the fragmented material is recuperated as by aspiration.
For deep veins extending more than 60 feet (18 m) deep into the surrounding strata, the waste rock surrounding the veins car be blasted ol~t~r the ore contained in the first 60 feet (18 m) deep ar so of the veins has bmn recovered as per the way described hereinbefore. In this way, the ore body o1~
tl~c;
vein can be fragmented and retrieved on another 60 feet (18 m) deep by repeating the above described steps from the new excavated bench level. It is understood that the 60 feet (18m) deep is dictated by the limits of the drilling equipment and is only given for illustrative purposes.
As shown in Fig. 3, for a three-bench extraction oh narrow v ein,, the stripping ratio is much less when using the thermal Ii-a~~mentatic>n minim';
concept. Because of the small size of the mobile equipment (the burner), thv I-ina pit shape can be kept as narrow as possible. This provides significant mining cost reduction. It is also advantageous in that it contributes to minimize dilution by avoiding stripping of waste.
The second bench level 40 is formed by blasting the waste rock =1?
surrounding the vein 12 after the ore body comprised in the lirst ('>f) legit ( 1 S »>) deep of the vein 12 has been retrieved from the first or surface level. :-liter. tl:e second bench level 40 has been excavated, the miring eduipment, including the drill and the burner, is moved onto the platform of the second bench level 40 and pilot holes are drilled and enlarged by thermal fragmentation as per the way described hereinbefore. The fragmented material is retrieved as by aspiration and the site is further excavated to form a third bench level 44 to permit retrieval of the remaining deepest portion of the vein I 2.
Fig. 4 is a schematic perspective view of a narro»- vein in the process of being grooved out by thermal fragmentation in accordance with a further embodiment of the present invention; and Fig. 5 is a schematic side elevation view illustrating a thermal fragmentation channeling operation carried out for extracting ore from a narrow vem.
DESCR1P'1'ION OF 7'HE PREFERRED EMBODINIIi\I'1'S
It is a problem in the field of mining to economically extract hi~~h grade materials, such as gold, platinum, copper or other precious materials, from a narrow vein of mineralization. A narrow vein of mineralization is normally not commercially mined because the return in volume of useable mineral ('or the amount of ore removed and the amount of labor required to remove the ore render it uneconomical to retrieve the desired minerals in a narrow vein application.
~s will be seen hereinafter, the present invention provides a solution to that particular problem by significantly minimizing the dilution of the hrccious mineral into the surrounding waste rock during the extraction operation 20 Unlike conventional mining methods which require that a ;great amount of commercially worthless rock (barren) be removed on either side o('the vein due to the utilization of explosive charges, the present free-blast mining method provides for the removal of the true value only, i.e. the extraction of the mineral deposit from the surrounding environment. 'l:~his rnay be rradilv 25 appreciated from Fig. 1 which shows a schematic comparison between the dilution associated with a conventional mining method and the present thermal fragmentation mining method. More particularly, according to the conventional long-hole mining method, blastholes 10 are drilled in the vein 12 and on either side thereof. Each blasthole 10 is filled with an explosive; charge., such as 30 dynamite, and the region in the vicinity of the blastholes 10 is li~agmentcd by the explosive power of the charge. This results in the formation of a large trench 1=1 which extends laterally outwardly of the vein sidewalk 16 along all the Ien~~th of vein 12. For instance, in the case of a vein having a 30 cm (12 inches) width, a trench of 140 cm (55 inches) in width will have to he blasted. This implies a dilution of about 55 cm (22 inches) on each side of the vein 12 throu~~hovt the 5 length thereof. That is to say that the amount of waste or commercially worthless material that has to be mined is significantly greater than the amount of material comprised between the vein sidewalk 16. Thc; ratio is about G tonnes of commercially worthless matter for 1 tonne of desired mineral.
hi contrast, according to the present invention, pilot holes 18 (not 10 blastholes) are defined directly in the vein 12 and subseduently cnla~-~~ecl or reamed by thermal fragmentation to the vein sidew~ulls 1G, thereby uvoiclin~~
dilution of the ore body contained in the vein in the commercially worthless matter located outwardly of the vein sidewalls l6. 'fhe trench can he kept us narrow as possible. This permits to extract 1 tonne of the desired mineral li>r 2 15 tonnes of gangue.
According to a preferred mode of extraction of the present invention, a first series 20 of three pilot holes 22, 24 and 2G are drilled dirr~tly into the vein 12 at predetermined longitudinal intervals, as shown in Fi'; 2.
Cho intervals are determined by the width of the vein 12. For a vein l~avin~~ a 12 20 inches (30 em) width, the pilot holes are preferably of about 6 inches ( l s cm) in diameter and spaced by a distance of about 21 inches (53 em). >ach pilot hole is between 40 feet (12 m) to 60 feet (18 m) deep and substantially center relative to a central axis of the vein 12. The broken material produced is recuperaicd Baud subsequently processed to separate the mineralized material from the barren.
25 The next step consists in the verification of the pilot holes 2?. ?=1 and 26. hi order to make sure that the pilot holes 22, 24 and 2G are in the vein 12, a conventional in-the-hole device (not shown) is used to locate the vein 12.
Once the ore is located in the pilot holes 22, 24 and 26, thermal fragmentation is started to enlarge each pilot hole to the sidewalk 16 of the vein 12. In practice, it is 30 understood that the pilot holes 22, 24 and 26 might in some instances be tlZermally reamed to a location which is located slightly outwardl~~ o(~ thc:-sidewalk 16 of the vein 12, as shown in dotted lines in Fig. 2. Each pilot hole is enlarged by lowering a strong burner (not shown), powered by diesel fuel and air, into the hole and by igniting it. The burner could also be provided in the form of a plasma torch, especially in underground mining operations. 'fhe heat ~~encratcd by 5 the burner raises the temperature in the hole up to 1800° C. 'this creates tl~ennnl stresses that span the rock. In simple terms, spalling is considered to he a Iurnn of decrepitation caused by an unequal expansion of rock crystals which overcomes molecule cohesion. The broken or fragmented material produced during this process ranges in size from fine grain to 4 cm (1.6 inch).
10 The first three pilot holes 22, 24 and 26 are preferably individually enlarged along all the length thereof from bottom to top in a predetermined sequence starting with the first hole 22, the third hole 26 and the second hole ?-1.
The broken material produced during the thermal fragmentation operation o1' the first and third holes 22 and 26 is preferably left in the holes to act as a thermal 15 barrier for preventing heat from escaping from the second hole 24 v~hen the pillars of material separating the second hole 24 from the first hole 22 and the second hole 24 from the third hole 26 start to become fragmented, thereby allowing heat to pass from the second hole 24 to tlne lust and the third holes ~?
and 26. By leaving the fragmented material in the holes until the thcr~nal 20 fragmentation is fully completed in the adjacent hole, signiticunt saving can be made in tern of thermal energy consumption. As shown in dotted lines in Fi~T.
~, the second hole 24 is enlarged to a greater extent than the first and third holes 22 and 26 so as to completely fragment the pillar between the first and second hc7les 22 and 24 and the pillar between the second and third holes 24 and 26.
25 Thereafter, a second series 28 oh pilot holes, comprisiy Uvo longitudinally spaced-apart holes 30 and 32, are drilled directly in the vein 1'? at the downstream end of the first series 20. The second pilot hole 32 of the second series 28 is first enlarged by thermal fragmentation followed by the first pilot hole 30. As for the first series 20, the fragmented material produced during the thermal 30 fragmentation performed in each hole is preferably left in the hole and the first pilot 30 is euarged to a greater extent than adjacent holes 26 and 32. As a ;~cr~cral rule, the holes which are enlarged to a large size are always comprised between two pairs of pilot holes which have already been enlarged. As represented by reference numeral 34 further pairs of longitudinally spacec-1-apart pilot holes 3G
and 38 are subsequently drilled and enlarged until the end of the vein I? is reached.
Once the vein I2 has been fragmented on all the length tlmmof or along a sufficient portion thereof, the fragmented material is recuperated as by aspiration.
For deep veins extending more than 60 feet (18 m) deep into the surrounding strata, the waste rock surrounding the veins car be blasted ol~t~r the ore contained in the first 60 feet (18 m) deep ar so of the veins has bmn recovered as per the way described hereinbefore. In this way, the ore body o1~
tl~c;
vein can be fragmented and retrieved on another 60 feet (18 m) deep by repeating the above described steps from the new excavated bench level. It is understood that the 60 feet (18m) deep is dictated by the limits of the drilling equipment and is only given for illustrative purposes.
As shown in Fig. 3, for a three-bench extraction oh narrow v ein,, the stripping ratio is much less when using the thermal Ii-a~~mentatic>n minim';
concept. Because of the small size of the mobile equipment (the burner), thv I-ina pit shape can be kept as narrow as possible. This provides significant mining cost reduction. It is also advantageous in that it contributes to minimize dilution by avoiding stripping of waste.
The second bench level 40 is formed by blasting the waste rock =1?
surrounding the vein 12 after the ore body comprised in the lirst ('>f) legit ( 1 S »>) deep of the vein 12 has been retrieved from the first or surface level. :-liter. tl:e second bench level 40 has been excavated, the miring eduipment, including the drill and the burner, is moved onto the platform of the second bench level 40 and pilot holes are drilled and enlarged by thermal fragmentation as per the way described hereinbefore. The fragmented material is retrieved as by aspiration and the site is further excavated to form a third bench level 44 to permit retrieval of the remaining deepest portion of the vein I 2.
The above described thermal fragmentation mining method can be adapted to either surface or underground mining.
According to a further general aspect of the present invention, thermal fragmentation is used to carry out a channeling oloeration directly into the ore vein deposit to proceed with the extraction of the ore body li-om the surrounding waste rock without having to drill pilot holes into the vein.
As shown in Fig. 4, the ore veal 12 is first localized and a vertical face 4G at one end of the vein 12 is exposed as by excavation. 'then, a vertical channel is cut in the exposed vertical face 46 between the rock walls 1 (i bordering the ore vein deposit. The vertical channel is obtained by directing the Ilamc:
generated by the burner against the exposed vertical (ace and by moving the burner vertically and sideways at a controlled rate of travel between the sidewalis 16 of the vein 12 to cause the ore comprised in the vein 12 to stall into fragments. The motion of the burner is confined within the boundaries o1~ the veilz, as indicated by arrows 48 and 50. The groove is gradu~nlly deepened by continuously re-adjusting the distance between the burner and the bottom of the groove. This distance is herein referred to as the "stand-off distance" and is substantially maintained constant through out the process. To do so, the burner could be mounted om a telescopic mast. Once the telescopic mast has been deployed to its fully extended position, the fragmented material is retrieved as by aspiration, the burner is withdrawn from the groove and the vertical tact 4(>
is blasted to expose a new vertical rock face from where it will be possible to continue the channeling operation of the vein 12. These steps are repeated until the ore vein '12 has been completely extracted.
Fig. 5 illustrates the adaptation of the above-described spallation channeling technique to an underground vein deposit. As for conventional underground mining operations, the ore vein 12 is sandwiched between top and bottom galleries 52 and 54. Access to the galleries 52 and 54 is provided by a vertical hole 56. The burner 58 is preferably mounted on a robot 60 louvered into the vertical hole SG. The robot 60 is adapted to vertically displace the burner 5~
between the top and bottom galleries 52 and 54 and sideways between the sidewalk of the vein 12. The heat generated by the burner 58 causes the ore body forming the vein 12 to span into chips. As the groove is being formed in the work face, the robot 58 advances further into the groove so as to maintain the burner ~8 at a substantially constant stand-off distance from the bottom of the vertical groove. Aspiration is conducted to retrieve the chips from the '~roovc. C)ncc tl~c groove has been deepen by a predetermined distance, a second vertical hole (not shown) is defined and the channeling process is repeated tcom this new hole.
iW
so repeating the above-described steps, the ore vein can be completely extracted, while avoiding undesired stripping of the surrounding waste rock. In this way, only the true value is extracted.
In summary, numerous advantages can be anticipated ~.v=hen looking at the present ore vein extracting process. In conventional ,clr:clive mining, a portion of waste rock has to be included in the mincable reserves to allow sufficient space for equipment and workers. As illustrated in l~i~~. 1.
by using the thermal fragmentation mining concept, the portion of waste rock to he excavated is minimal. Therefore, significant savings related to ore handlin~~, ore treatment and environmental control can be realized.
_g_
According to a further general aspect of the present invention, thermal fragmentation is used to carry out a channeling oloeration directly into the ore vein deposit to proceed with the extraction of the ore body li-om the surrounding waste rock without having to drill pilot holes into the vein.
As shown in Fig. 4, the ore veal 12 is first localized and a vertical face 4G at one end of the vein 12 is exposed as by excavation. 'then, a vertical channel is cut in the exposed vertical face 46 between the rock walls 1 (i bordering the ore vein deposit. The vertical channel is obtained by directing the Ilamc:
generated by the burner against the exposed vertical (ace and by moving the burner vertically and sideways at a controlled rate of travel between the sidewalis 16 of the vein 12 to cause the ore comprised in the vein 12 to stall into fragments. The motion of the burner is confined within the boundaries o1~ the veilz, as indicated by arrows 48 and 50. The groove is gradu~nlly deepened by continuously re-adjusting the distance between the burner and the bottom of the groove. This distance is herein referred to as the "stand-off distance" and is substantially maintained constant through out the process. To do so, the burner could be mounted om a telescopic mast. Once the telescopic mast has been deployed to its fully extended position, the fragmented material is retrieved as by aspiration, the burner is withdrawn from the groove and the vertical tact 4(>
is blasted to expose a new vertical rock face from where it will be possible to continue the channeling operation of the vein 12. These steps are repeated until the ore vein '12 has been completely extracted.
Fig. 5 illustrates the adaptation of the above-described spallation channeling technique to an underground vein deposit. As for conventional underground mining operations, the ore vein 12 is sandwiched between top and bottom galleries 52 and 54. Access to the galleries 52 and 54 is provided by a vertical hole 56. The burner 58 is preferably mounted on a robot 60 louvered into the vertical hole SG. The robot 60 is adapted to vertically displace the burner 5~
between the top and bottom galleries 52 and 54 and sideways between the sidewalk of the vein 12. The heat generated by the burner 58 causes the ore body forming the vein 12 to span into chips. As the groove is being formed in the work face, the robot 58 advances further into the groove so as to maintain the burner ~8 at a substantially constant stand-off distance from the bottom of the vertical groove. Aspiration is conducted to retrieve the chips from the '~roovc. C)ncc tl~c groove has been deepen by a predetermined distance, a second vertical hole (not shown) is defined and the channeling process is repeated tcom this new hole.
iW
so repeating the above-described steps, the ore vein can be completely extracted, while avoiding undesired stripping of the surrounding waste rock. In this way, only the true value is extracted.
In summary, numerous advantages can be anticipated ~.v=hen looking at the present ore vein extracting process. In conventional ,clr:clive mining, a portion of waste rock has to be included in the mincable reserves to allow sufficient space for equipment and workers. As illustrated in l~i~~. 1.
by using the thermal fragmentation mining concept, the portion of waste rock to he excavated is minimal. Therefore, significant savings related to ore handlin~~, ore treatment and environmental control can be realized.
_g_
Claims (7)
1. A method for extracting ore from an ore vein deposit bordered by rock walls, comprising the steps of a) establishing the location of the rock walls bordering the ore vein deposit, b) using thermal fragmentation, causing the ore comprised between the rock walls to spall into fragments, and c) retrieving the fragments by aspiration, wherein step b) comprises moving a burner at a controlled rate of travel between the rock walls, and adjusting a distance between the burner and an exposed face of the ore vein as the ore is being thermally fragmented.
2. A method as defined in claim 1, wherein step b) comprises the steps of drilling pilot holes directly in the ore vein deposit at specific intervals therealong, and using thermal fragmentation, enlarging the pilot holes until the vein is fragmented.
3. A method as defined in claim 2, wherein the intervals are determined by the width of the vein.
4. A method as defined in claim 2, wherein along at least a portion of the length of the vein, the pilot holes are successively enlarged according to a predetermined pattern wherein every other pilot hole is enlarged to a greater extent so as to merge with opposed adjacent pilot holes which have been previously enlarged.
5. A method as defined in claim 4, wherein the pilot holes are drilled and enlarged in a predetermined sequence starting by the drilling of a first series of three pilot holes, the first and third holes of said first series being enlarged prior to the second hole of the series.
6. A method as defined in claim 5, wherein said first series of holes is followed by a second series of two holes, the second hole of the second series being enlarged prior to the first hole of the second series.
7. A method as defined in claim 1, comprising maintaining the burner at a substantially constant stand-off distance from the exposed face of the ore vein throughout the thermal fragmentation step.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2539268A CA2539268C (en) | 2002-11-26 | 2003-11-26 | Thermal rock fragmentation application in narrow vein extraction |
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2412792 CA2412792A1 (en) | 2002-11-26 | 2002-11-26 | Thermal rock fragmentation application in narrow vein extraction |
| CA2,412,792 | 2002-11-26 | ||
| CA002495143A CA2495143C (en) | 2002-11-26 | 2003-11-26 | Thermal rock fragmentation application in narrow vein extraction |
| PCT/CA2003/001844 WO2004048753A1 (en) | 2002-11-26 | 2003-11-26 | Thermal rock fragmentation application in narrow vein extraction |
| CAPCT/CA2003/001844 | 2003-11-26 | ||
| CA2539268A CA2539268C (en) | 2002-11-26 | 2003-11-26 | Thermal rock fragmentation application in narrow vein extraction |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002495143A Division CA2495143C (en) | 2002-11-26 | 2003-11-26 | Thermal rock fragmentation application in narrow vein extraction |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2539268A1 CA2539268A1 (en) | 2004-06-10 |
| CA2539268C true CA2539268C (en) | 2011-06-14 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002495143A Expired - Lifetime CA2495143C (en) | 2002-11-26 | 2003-11-26 | Thermal rock fragmentation application in narrow vein extraction |
| CA2539268A Expired - Lifetime CA2539268C (en) | 2002-11-26 | 2003-11-26 | Thermal rock fragmentation application in narrow vein extraction |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002495143A Expired - Lifetime CA2495143C (en) | 2002-11-26 | 2003-11-26 | Thermal rock fragmentation application in narrow vein extraction |
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| Country | Link |
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| CA (2) | CA2495143C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| MX2010001313A (en) * | 2007-08-02 | 2010-04-07 | Rocmec Internat Inc | Ore extraction using combined blast and thermal fragmentation. |
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2003
- 2003-11-26 CA CA002495143A patent/CA2495143C/en not_active Expired - Lifetime
- 2003-11-26 CA CA2539268A patent/CA2539268C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA2539268A1 (en) | 2004-06-10 |
| CA2495143C (en) | 2006-06-06 |
| CA2495143A1 (en) | 2004-06-10 |
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