RU2332567C2 - Method of ore extraction from narrow veins employing thermal fragmentation of ore - Google Patents

Abstract

FIELD: mining industry.

SUBSTANCE: present invention relates to the field mining using thermal fragmentation for the extraction of ore from narrow veins. The method of ore extraction from a vein with opposite side walls involves drilling of pilot holes in the vein directly, with certain pitch along the vein, reaming of the pilot holes by thermal fragmentation until the vein is fragmented, and removal of fragmented ore along the vein. The pitch is determined by the vein width. Along a part of the vein, the pilot holes are reamed gradually according to the given configuration, each second pilot hole is reamed in a greater degree, for its connection to the opposite adjacent pilot holes reamed earlier. The pilot holes are drilled and reamed in a given sequence, starting from drilling of the first group of three pilot holes, the first and third holes from the first group are reamed before reaming the second hole from this group. After the first group of holes, a group of two holes is drilled, the second hole from the second group being reamed before reaming the first hole from the second group. Fragmented ore is removed by suction.

EFFECT: profitable mining of narrow ore veins.

7 cl, 6 dwg

Description

The present invention relates to the extraction of ores and more specifically to the development of deposits with thermal crushing for the extraction of ore from thin veins.

Over the years, mining companies have continued to work on creating various ways to mechanize mining. They succeeded in many cases when the ore volume was sufficient to justify large capital investments in equipment and the necessary infrastructure. Mineral deposits in thin veins, for their part, were a big problem in terms of mechanization. Selective development methods, such as shopping, have been replaced by the use of a deep well mechanized production method. Despite all the efforts made, successful cases remain rare. The complexity of regulating the stability of the walls after vibrations caused by explosions often led to strong dilution, which did not make the development of thin veins economically viable. Indeed, the development of veins with a small cross-section in the past was uneconomical, because with modern methods of developing deposits, a thin vein requires the removal of a large amount of waste rock on both sides of the vein. In this case, a large amount of ore must be processed to extract a small amount of the desired minerals.

Therefore, a large number of known thin mineralized veins are not currently being developed, since the extraction of such minerals is not viable in specific economic conditions due to limitations due to current mining methods.

Therefore, the aim of the present invention is to develop a new method of mining ore to enable cost-effective development of thin ore veins.

An additional objective of the present invention is to develop a new and effective approach to the development of deposits for the extraction of ore from thin veins.

Another objective of the present invention is to optimize ore recovery.

An additional objective of the present invention is to develop a new method of mining ore from thin veins, in which the weakening of the walls of the vein is minimal.

Therefore, in accordance with the present invention, a method for producing ore from a core having opposite side walls is developed, in which leading wells are drilled directly in the core at certain intervals along it, expand leading wells by using thermal crushing to crush the core and extract crushed ore along the core.

When implementing the method, the intervals can be determined by the width of the core.

At least along part of the length of the core leading wells can be sequentially expanded in accordance with a given configuration, with each second leading well can be expanded to a greater extent for its connection with the opposite neighboring leading wells, previously expanded.

Leading wells can be expanded to the side walls of the core.

Leading wells can be drilled and expanded in a predetermined sequence, starting from drilling the first group of three leading wells, while the first and third wells from the first group are expanded before the expansion of the second well from this group. The first group of wells can be followed by a group of two wells, while the second well from the second group is expanded before the expansion of the first well from the second group.

In the process, the crushed ore can be recovered by suction.

The following is a detailed description of a preferred embodiment of the invention with reference to the accompanying drawings, which depict the following:

figure 1 is a comparative diagram of a method of developing fields using deep wells with a method of developing fields using thermal crushing in accordance with a preferred embodiment of the present invention;

FIG. 2 is a schematic plan view from above of an ore core illustrating ore recovery by thermal crushing of a rock; FIG.

figure 3 is a schematic vertical view showing a diagram of a recess on the surface, which can be used in the extraction of thin veins by thermal crushing;

FIG. 4 is a schematic perspective view of a thin core in a process of excavation by thermal crushing in accordance with a further embodiment of the present invention; FIG.

5 is a schematic vertical side view illustrating a channel forming operation by thermal crushing performed to extract ore from a thin core.

In the field of mining, there is a problem associated with the economical extraction of high quality valuable materials, such as gold, platinum, copper or other precious materials, from thin ore veins. Thin ore veins are usually not industrially developed, since the yield by volume of useful mineral on the amount of ore recovered and the amount of labor required to extract ore make it uneconomical to extract the desired minerals in the case of thin veins. As will be seen below, in accordance with the present invention, a solution to this particular problem is proposed by substantially minimizing the dilution ("withdrawal") of the valuable mineral into the surrounding waste rock during the mining operation.

Unlike traditional methods of developing deposits, which require a large amount of commercially useless rock (not containing minerals) to be removed from both sides of the core due to the use of explosive charges, this method of developing deposits without explosions provides the extraction of only really valuable , that is, the extraction ("extraction") of minerals from the environment. This can be easily understood from FIG. 1, which illustrates a schematic comparison between dilution related to the conventional field development method and the thermal crushing field development method of the present invention. More precisely, in accordance with the conventional development method using deep wells, blast holes (holes) 10 are drilled in core 12 and on both sides thereof. Each hole 10 is filled with a charge of an explosive, such as dynamite, and the area near the holes 10 is crushed due to the force of the explosion of the charge. This leads to the formation of a large trench 14, which extends laterally outward with respect to the side walls 16 of the core along the entire length of the core 12. For example, in the case of a core having a width of 30 cm (12 inches), a trench of 140 wide should be obtained by blasting cm (55 inches). This results in the destruction of approximately 55 cm (22 inches) on each side of the core 12 along its entire length. In other words, the amount of gangue or commercial useless material to be mined substantially exceeds the amount of material contained between the side walls 16 of the core. The ratio is about 6 tons of commercially useless material per 1 ton of the desired mineral.

In contrast, in accordance with the present invention, leading wells 18 (non-blast holes) are formed directly in core 12 and subsequently drilled or expanded by thermal crushing to the side walls 16 of the core, thereby avoiding dilution of the ore body contained in the core due to " care "him to useless from a commercial point of view material located outside the side walls 16 of the core. The trench can be kept as narrow as possible. This allows you to mine 1 ton of the desired mineral per 2 tons of waste rock.

According to a preferred production method of the present invention, a first group 20 of three leading wells 22, 24, 26 is drilled directly in the core 12 at predetermined intervals in the longitudinal direction, as shown in FIG. 2. The intervals are determined by the width of the core 12. For a core having a width of 12 inches (30 cm), leading wells preferably have a diameter of approximately 6 inches (15 cm) and are spaced apart by approximately 21 inches (53 cm). Each leading well has a depth of 40 feet (12 m) to 60 feet (18 m) and is located essentially in the center relative to the central axis of the core 12. The resulting crushed material is recovered and subsequently processed to separate the mineralized material from the gangue.

The next step is to check the leading wells 22, 24, 26. In order to make sure that the leading wells 22, 24, 26 are in the core 12, use a conventional immersion device (not shown) to determine the location of the core 12. Once the ore is found in leading wells 22, 24, 26, thermal crushing is started to expand each leading well to the side walls 16 of the core. It should be understood that in practice leading wells 22, 24, 26 in some cases can be thermally expanded to a place that is slightly outside relative to the side walls 16 of core 12, as shown by dashed lines in FIG. Each leading well is expanded by lowering a powerful burner (not shown) running on diesel fuel and air into the well and igniting it. The burner can also be made in the form of a plasma torch, especially during underground mining operations. The heat generated by the burner causes a rise in temperature in the well to 1800 ° C. This creates thermal stresses that cause crushing of the rock. In simple terms, cracking is considered a type of cracking of crystals caused by unequal expansion of rock crystals, which “overcomes” the cohesive force of the molecules. Crushed or crushed into pieces, the material obtained during this process varies in size from fine grain to 4 cm (1.6 inches).

The first three leading wells 22, 24, 26 are preferably expanded individually along their entire length from bottom to top in a predetermined sequence, starting from the first well 22, then the third well 26 and the second well 24. The crushed material obtained during the thermal crushing operation in the first and third wells 22 and 26 are preferably left in the wells so that it serves as a thermal barrier to prevent heat leakage from the second well 24 when pillars of material separating the second well 24 from the first the first well 22 and the second well 24 from the third well 26, begin to fragment, thereby creating the possibility of heat transfer from the second well 24 to the first and third wells 22 and 26. Due to the fact that the crushed material is left in the wells until the thermal crushing in to a neighboring well, significant savings in terms of energy consumption can be achieved. As shown by dashed lines in FIG. 2, the second well 24 is expanded to a greater extent than the first and third wells 22 and 26 to completely fragment the pillar between the first and second wells 22 and 24 and the pillar between the second and third wells 24 and 26.

After that, the second group of leading wells 28, containing two wells 30 and 32 located at a certain distance from each other in the longitudinal direction, is drilled directly in the core 12 at the downstream end of the first group 20. First, the second leading well 32 from the second group 28 is expanded by thermal crushing, followed by the first leading well 30. As in the case of the first group 20, the crushed material obtained during thermal crushing performed in each well is preferably left in the well and the first well 30 extend to a greater degree than the adjacent wells 26 and 32. Typically, the wells are expanded to large in size, always between two pairs of pre-drilled wells which have been expanded. As indicated by reference numeral 34, then additional pairs of leading wells 36 and 38 located at a certain distance from each other in the longitudinal direction are then drilled and expanded until the end of the core 12 is reached.

As soon as the core 12 is crushed along its entire length or along a sufficient part of it, the crushed material is removed (captured) by suction.

In the case of deep veins extending more than 60 feet (18 m) into the depth of the surrounding formations, the gangue surrounding the veins may be exploded after the ore contained in or near the first 60 feet (18 m) of the vein depth will be extracted as described above. Thus, the ore body of the core can be crushed and extracted at another 60 feet (18 m) of depth by repeating the above operations from the level of the new ledge obtained by excavation. It should be understood that a value of 60 feet (18 m) of depth is determined by the ultimate characteristics of the drilling equipment and is provided for illustrative purposes only.

As shown in figure 3, when mining from thin veins, carried out with three ledges, the stripping ratio will be significantly lower when using the concept of field development using thermal crushing. Due to the small size of the mobile equipment (burner), the final shape of the excavation can be kept as narrow as possible. This provides a significant reduction in field development costs. This is also preferable because it helps to minimize dilution by avoiding overburden.

Level 40 of the second ledge is formed by blasting rock 42 surrounding the core 12 after the ore body contained in the first 60 feet (18 m) of the depth of core 12 is removed from the first level or surface level. After excavation to level 40 of the second step is completed, mining equipment, including a drill and a burner, is moved to the platform at level 40 of the second step and leading wells are drilled and expanded by thermal crushing, as described above. The crushed material is extracted by suction and additional excavation is carried out at this location to form level 44 of the third ledge to enable extraction of the remaining deepest part of the core 12.

The above-described method of developing deposits using thermal crushing can be adapted to either open pit mining or underground mining.

In accordance with a further general aspect of the present invention, thermal crushing is used to perform channelization operations directly in an ore vein deposit, followed by extraction of the ore body from surrounding gangue without the need to drill leading wells in the vein.

As shown in FIG. 4, the location of the ore core 12 is first determined and then a vertical face (surface) 46 at one end of the core 12 is exposed for excavation. After that, the vertical channel is cut in the vertical face 46 open to the impact between the rock walls 16, bounding the ore vein deposit. The vertical channel is obtained by directing the flame formed by the burner towards the vertical face open to the impact and by moving the burner in the vertical and lateral directions with an adjustable speed of movement between the side walls 16 of the core 12 to cause crushing of the ore contained in the core 12 into fragments. The movement of the burner is limited by the boundaries of the core, as shown by arrows 48 and 50. The recess is gradually deepened by continuously adjusting the distance between the burner and the bottom of the recess. This distance is referred to herein as the “dividing distance” and is maintained substantially constant throughout the process. To accomplish this, the burner can be mounted on a telescopic mast. After the telescopic mast has been deployed to its fully extended position, the crushed material is removed by suction, the burner is removed from the recess and the vertical face 46 is blasted in order to expose a new vertical face plane from which channeling can continue in the core 12 These operations are repeated until mining from the ore core 12 is completely completed.

5 illustrates an adaptation of the channelization method described above by cracking fracture for an underground vein deposit. As in the case of conventional underground mining, the ore core 12 is located between the upper and lower drifts 52 and 54. Access to the drifts 52 and 54 is provided through a vertical well 56. The burner 58 is preferably mounted on a robot 60, lowered into a vertical well 56. Robot 60 made with the possibility of shifting the burner 58 in the vertical direction between the upper and lower drifts 52 and 54 and in the lateral direction between the side walls of the core 12. The heat created by the burner 58 causes the ore body forming the core 12 to be crushed into small pieces ie fragments. As a recess in the face is formed, the robot 60 moves forward further into the recess in order to keep the burner 58 at a substantially constant dividing distance from the bottom of the vertical recess. Suction is performed to extract fines from the recess. As soon as the recess is deepened by a predetermined distance, a second vertical well (not shown) is formed and the channeling process is repeated from this new well. By repeating the operations described above in such a way, the development (mining) of the ore core can be completely carried out while avoiding undesirable overburden of surrounding waste rock. Thus, only true value is mined.

Summing up, we can say that you can expect many advantages when considering the method of extraction from ore vein according to the present invention. In conventional selective mining, part of the gangue should be included in recoverable reserves to ensure that there is sufficient space for equipment and workers. As illustrated in FIG. 1, by using the concept of field development using thermal crushing, the proportion of gangue to be recovered is minimal. Consequently, significant savings can be achieved associated with the transportation, loading and unloading of ore, ore processing and environmental monitoring.

Claims (7)

1. A method of mining ore from a core having opposite side walls, in which leading wells are drilled directly in the core at certain intervals along it, expand the leading wells by using thermal crushing to crush the core and extract the crushed ore along the core. 2. The method according to claim 1, in which the intervals are determined by the width of the core. 3. The method according to claim 1, in which, at least along part of the length of the lead well conductor, is sequentially expanded in accordance with a given configuration, while each second leading well is expanded to a greater extent for its connection with opposite neighboring leading wells, previously expanded . 4. The method according to claim 1, in which the leading wells are expanded to the side walls of the core. 5. The method according to claim 3, in which leading wells are drilled and expanded in a predetermined sequence, starting from drilling the first group of three leading wells, while the first and third wells from the first group are expanded before the expansion of the second well from this group. 6. The method according to claim 5, in which the first group of wells is followed by a group of two wells, while the second well from the second group is expanded before the expansion of the first well from the second group. 7. The method according to claim 1, in which the crushed ore is extracted by absorption.

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