A mechanized room-and-pillar mining method for gently inclined thin to extremely thin veins of precious metals

Abstract

The present invention discloses a mechanized room-and-pillar mining method for gently inclined thin to extremely thin veins of precious metals, which relates to the technical field of ore deposit mining, and includes Step 1: Arrangement of the working face of the ore body; Step 2: Development and cutting; Step 3: Stoping: The mining sequence is to advance from bottom to top, first mining the surrounding rock and then the ore body; Step 4: Mucking and ore drawing; The present invention is reasonably designed and has a simple mining method, which can effectively solve the problems of multiple processes, complex technology, high dilution rate, low mechanization degree, low efficiency, high labor intensity of workers and poor safety in the process of mining gently inclined precious metal deposits in thin to extremely thin veins.

Description

Technical Field

[0001] The present invention relates to the technical field of ore deposit mining, and more specifically to the technical field of a mechanized room-and-pillar mining method for gently inclined thin to extremely thin ore veins of precious metals. Background Art

[0002] Gently inclined thin ore veins are one of the main occurrence forms of non-ferrous metal ore veins in China, especially accounting for a large proportion in deposits such as gold, silver, molybdenum, tin, tungsten, and antimony. Gently inclined thin ore veins refer to ore bodies with an inclination angle less than 30° and a thickness less than 0.8 m. For this part of the ore bodies, due to the gentle inclination and thin veins, personnel cannot stand and work in the stope, and mechanized equipment cannot enter, resulting in inability to mine. The current common practice in China is to carry out wall scraping stoping. The wall scraping stoping process is numerous and complex, the stoping width is too large, the ore dilution rate is large, and the dilution rate of mining extremely thin ore veins is even as high as 80%; the mechanization degree is low, the labor intensity is large; the material consumption is high, and the personnel efficiency is low; personnel need to enter the stope, and the operation safety is affected to a certain extent; the mining cost is high, and the economic benefit is poor.

[0003] In recent years, with the research and development of mechanized low height, some problems of low mechanization in thin ore vein stoping have been solved. However, for the stoping of extremely thin ore veins, there is currently no good method. How to solve the above technical problems has become the direction of efforts of those skilled in the art. Summary of the Invention

[0004] The purpose of the present invention is: to solve the above technical problems, the present invention provides a mechanized room-and-pillar mining method for gently inclined thin to extremely thin ore veins of precious metals.

[0005] The present invention specifically adopts the following technical solutions to achieve the above purpose:

[0006] A mechanized room-and-pillar mining method for gently inclined thin to extremely thin ore veins of precious metals, comprising the following steps:

[0007] Step 1. Ore body working face layout

[0008] a. Ore block division: Set isolation barrier pillars every 180 - 200 m along the ore body strike, divide the ore body into several panels, and take 50 - 60 m along the ore body strike in each panel as an ore block. Each ore block is equally spaced with stoping headings, and the stoping headings divide each ore block into multiple strips;

[0009] b. Ore block composition: Bottom pillars and top pillars are arranged at the upper and lower ends of the ore block. A lower stage haulage drift is arranged below the bottom pillar, and the lower stage haulage drift is arranged along the ore vein. An upper stage return airway for ore block stoping and ventilation is arranged above the top pillar, using the upper stage crosscut haulage airway.

[0010] c. Ore room layout: Each ore block is divided into several ore rooms perpendicular to the ore body strike, and multiple regular room pillars are left in each ore room;

[0011] Step 2: Mining Preparation and Cutting

[0012] d. Cut the haulage drift: Cut the lower-stage haulage drift, the stage return airway, and the stage haulage drift according to step b. The lower-stage haulage drift, the upper-stage return airway, and the stage haulage drift are all arranged in the footwall rock stratum along the strike of the ore body, and cut along the strike of the ore body;

[0013] e. Cut the stoping entry: In step c, a stoping entry is cut between two adjacent ore rooms. The upper end of the stoping entry communicates with the upper-stage return airway, and the lower end of the stoping entry communicates with the lower-stage haulage drift. The cross-section of the stoping entry is not less than the minimum working space of the equipment to ensure that the small-sized LHD can turn around normally. The ore block is divided into multiple strips through the stoping entry;

[0014] f. Cut the undercut drift: After leaving a sill pillar at the lower part of the ore block, drive and cut along the strike of the ore body to form an undercut drift. The cross-section of the undercut drift is not less than the minimum working space of the equipment, and expand the undercut drift to both sides of the ore body to form an undercut space;

[0015] Step 3: Stoping: The overall mining sequence in the panel is retreating stoping, and each strip in the ore block is mined along the reverse dip of the ore body;

[0016] g. There is footwall rock at the lower part of the ore body. First, mine the footwall rock. When mining the footwall rock, the lower part is 5 - 6 m ahead of the inclined ore body, and the mining thickness of the footwall rock is 1.5 - 2 m. After the footwall rock collapses, directly use the LHD or mucking machine to clear and transport the footwall rock, and the cleared space is used as the ore drawing space for the next step of ore mining;

[0017] h. After clearing the footwall rock, mine the ore body. After the ore body collapses, use the LHD to transport it out. When mining the ore body, it is necessary to control the depth of the blast holes and not break the roof;

[0018] Step 4: Mucking and Ore Drawing

[0019] Both mucking and ore drawing are carried out using a 0.6 m³ internal combustion LHD or mucking machine. The collapsed footwall rock and ore are loaded into small-sized trackless mining trucks in batches and separately, and directly transported away along the stoping entry and the stage haulage drift.

[0020] Furthermore, in step b, the height of the ore block in the same stage is 20 - 30 m, the width of the ore block is 50 m, the width of the ore room is 12.5 m, the width of the continuous isolation pillar is not less than 8 m, the width of the crown pillar is 4 m, and the width of the sill pillar is 4 m.

[0021] Furthermore, in step c, the length and width of the room-and-pillar are 2.0 × 3.0 m.

[0022] The beneficial effects of the present invention are as follows:

[0023] 1. The present invention is reasonably designed and has a simple mining method, which can effectively solve the problems existing in the mining method for gently inclined precious metal thin to extremely thin ore veins, such as many processes, complex technology, high dilution rate, low mechanization level, low efficiency, high labor intensity of workers, and poor safety.

[0024] 2. Using a load-haul-dump (LHD) machine to remove slag first and then ore, it has a high mechanization level and high production efficiency; the process is relatively simple and easy for workers to operate and master.

[0025] 3. Using a load-haul-dump (LHD) machine or a mucking machine to extract ore and directly load it into the ore cars in the off-vein transportation roadway, without the need for transfer, with high efficiency, which can greatly improve the ore extraction capacity and at the same time shorten the exposure time of the open stope; due to the large amount of engineering work of the floor surrounding rock, this method is applicable to ore bodies such as precious metals with high ore value. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic structural diagram of the present invention;

[0027] Figure 2 is Figure 1 a cross-sectional view taken along line II-II in

[0028] Figure 3 is a mining sequence diagram;

[0029] Reference numerals: 1. Cross-vein transportation roadway; 2. Cut-and-fill drift; 3. Stoping drift; 4. Room pillar; 5. Stoping ore heap; 6. Crown pillar; 7. Sill pillar; 8. Ore body; 9. Surrounding rock; 10. Upper stage return airway 11. Load-haul-dump (LHD) machine 12. Roof surrounding rock; 14. Floor surrounding rock; 15. Blasthole. DETAILED DESCRIPTION OF THE INVENTION

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0032] It should be noted that: Similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In addition, terms such as "first", "second", etc. are only used for descriptive distinction and cannot be construed as indicating or implying relative importance.

[0033] In the description of the embodiments of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "inside", "outside", "above", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the inventive product is customarily placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation on the present invention.

[0034] Embodiment 1

[0035] As Figures 1 to 3 shown, this embodiment provides a mechanized room-and-pillar mining method for gently inclined thin to extremely thin precious metal ore veins. The ore layer mined in this embodiment is a precious metal deposit with an inclination angle of less than 30° and a thickness of less than 0.8 m, and includes the following steps:

[0036] Step 1. Orebody working face layout

[0037] a. Ore block division: Isolation intermediate pillars are set at intervals of about 200 m along the strike of the orebody, dividing the orebody into several panels. Generally, 50 - 60 m in each panel is used as an ore block, and stoping headings are set at equal intervals of 12.5 m in each ore block, divided into multiple strips;

[0038] b. Ore block composition: Bottom pillars and top pillars at the upper and lower ends of the ore block. A lower stage haulage drift is arranged below the bottom pillar, and the lower stage haulage drift is arranged along the ore vein. An upper stage return airway using the upper stage crosscut along the vein as the ore block stoping return air is arranged above the top pillar; The height of the ore blocks in the same stage is 20 - 30 m, the width of the ore block is 50 m, the width of the ore room is 12.5 m, a continuous isolation intermediate pillar is set every 200 m, the width of the continuous isolation intermediate pillar is 8 m, the width of the ore block top pillar is 4 m, and the width of the bottom pillar is 4 m.

[0039] c. Ore room layout: Each ore block is divided into several ore rooms perpendicular to the strike of the orebody, and multiple room pillars are left in each ore room;

[0040] Step 2: Development and cutting

[0041] d. Cutting and haulage drift: Cut the lower stage haulage drift, the upper stage return airway and the stage vein haulage drift according to step b. The lower stage haulage drift, the upper stage return airway and the stage haulage drift are all arranged in the footwall rock formation along the strike of the inclined orebody and cut along the strike of the orebody;

[0042] e. Cut-and-fill drifts: In step c, cut-and-fill drifts are made between two adjacent ore rooms. The upper end of the cut-and-fill drift communicates with the upper-stage return airway, and the lower end communicates with the lower-stage transportation roadway. The cross-section of the cut-and-fill drift is not less than the minimum working space of the equipment to ensure that the small load-haul-dump can be turned around normally. The ore block is divided into multiple strips through the cut-and-fill drift; the cross-section of the cut-and-fill drift is not less than 2.5 m × 2.5 m.

[0043] f. Cut-and-bottom drifts: After leaving a sill pillar at the lower part of the ore block, drive a cut-and-bottom drift along the strike of the ore body. The cross-section of the cut-and-bottom drift is not less than the minimum working space of the equipment, and the cut-and-bottom drift is extended to both sides of the ore body to form a bottom-drawing space; the height of the sill pillar is 4 m.

[0044] Step 3: Stoping: The mining sequence between panels is retreating stoping, and each strip in the ore block within the panel is mined along the reverse dip of the ore body (from bottom to top).

[0045] g. There is lower surrounding rock at the lower part of the ore body. First, mine the lower surrounding rock. When mining the surrounding rock, the lower part is advanced 5 - 6 m ahead of the inclined ore body, and the mined thickness of the surrounding rock is 1.5 - 2 m; just ensure the minimum working height of the small load-haul-dump. After the surrounding rock is caved, use the small load-haul-dump to shovel, transport, and load out the surrounding rock to complete the cleaning of the surrounding rock.

[0046] h. After the surrounding rock is cleared, mine the ore body. After the ore body is caved, it is transported out by a load-haul-dump. When mining the ore body, the depth of the blast holes needs to be controlled to avoid damaging the roof.

[0047] Since the ore body is relatively thin, less than 0.8 m, people cannot stand and equipment cannot enter the stope. Therefore, during stoping, it is mined in two steps. First, mine the lower surrounding rock. The surrounding rock mining is generally 5 - 6 m ahead of the ore body, and the mined thickness of the surrounding rock is 1.5 - 2 m, just ensuring the minimum working height of the load-haul-dump. After the surrounding rock is caved, use the small load-haul-dump to shovel, transport, and load out the surrounding rock. After the surrounding rock is cleared, mine the ore body in the second step. After the ore body is caved, it is transported out by a load-haul-dump. When mining the ore body, the depth of the blast holes needs to be controlled to avoid damaging the roof.

[0048] Stoping sequence: The stoping face is advanced in the reverse dip direction (upward stoping), that is, mining from the cut-and-fill drift to both sides of the ore room, and then advancing in the reverse dip direction from bottom to top.

[0049] Setting of room pillars: During stoping, rectangular room pillars are set every 8 - 10 m, and the pillar size is 2.0 × 3.0 m.

[0050] Rock drilling: To control the height of the surrounding rock and ore extraction width, a small-diameter drill bit with a diameter of 32 - 35 mm is used for stope rock drilling. The blasting effect is good, which is significant for controlling the extraction width and reducing dilution. The stope working face advances in a single-step manner, and a rock drill is used to drill upwardly inclined blast holes. The design adopts a linear arrangement. The ore has good blastability, and the ore is easy to separate from the surrounding rock. The blast hole spacing is mainly affected by two factors, namely, the occurrence conditions of the ore vein (ore vein thickness, stability, grade, ore-rock boundary, etc.) and technical factors (blast hole diameter, charge density, explosive density and performance, etc.). For the blast hole network parameters, the blast hole spacing in the ore vein is 0.4 - 1.0 m, and the blast hole spacing in the surrounding rock is 0.6 - 1.2 m.

[0051] Blasting: The depth of the blast holes is controlled at 1.2 - 1.8 m. The charging length accounts for 2 / 3 of the blast hole depth. After charging, stemming is used to block the hole mouth, and the stemming length is greater than 100 mm. Emulsion explosive is used for blasting. Non-electric detonating tube millisecond-delay detonators are used for detonation, and an electronic initiator is used for initiation.

[0052] Ventilation: Fresh air flows into the lower-stage transportation roadway and stoping entry under the action of the main mine air pressure, washes the working face, and then the polluted air is discharged to the upper-stage return airway. Ventilation is carried out after stope blasting. After the blast fumes are completely exhausted and the toxic and harmful gas detection is qualified, personnel can re-enter the stope.

[0053] Step 4: Mucking and ore drawing

[0054] For both ore drawing and mucking, a 0.6 m³ internal combustion load-haul-dump (LHD) or mucking loader is used to load the caved surrounding rock and ore into small trackless mine trucks in batches and separately, and then directly transported away along the stoping entry and stage transportation roadway.

[0055] The following treatments are also required during and after the implementation of the method of this embodiment:

[0056] Roof management: During the stoping of the ore room, irregular ore pillars are left as required according to the stability of the roof and floor to support the roof and floor. As much lean ore or part of the low-grade ore as possible is left as ore pillars, with the ore pillars being 2.0 × 3.0 m. When the stability of the ore body roof surrounding rock is poor or the exposed area of the ore room is large, anchor nets, etc. are used for reinforcement. Swelling cement cartridge bolts are used as bolts, with the bolt length being 2 m, the bolt hole diameter being 22 - 25 mm, and the spacing being 1 m × 1 m - 1.5 m × 1.5 m. The steel wire mesh uses round steel.

[0057] Ore pillar stoping: The regular ore pillars and crown pillars left in the ore room are not recovered, and the intermediate pillars can be appropriately recovered according to the actual situation. The sill pillar can be appropriately recovered during the stoping of the lower-stage ore room.

[0058] Goaf treatment: After the stoping of the ore room, all the ore drawing entries, raise crosscuts leading to the goaf, etc. are blocked and allowed to cave in naturally. Safety warning signs should be set after the roadways leading to the goaf are blocked.

Claims

1. A mechanized room-and-pillar mining method for gently inclined thin to extremely thin veins of precious metals, characterized in that, It includes the following steps: Step 1: Layout of the ore body working face a. Ore block division: Isolation interval pillars are set every 180 - 200 m along the strike of the ore body to divide the ore body into several panels. Each panel is 50 - 60 m along the strike of the ore body as an ore block. Stoping headings are set at equal intervals in each ore block, and each ore block is divided into multiple strips by the stoping headings; b. Ore block structure: Pillars are set at the upper and lower ends of the ore block. A lower - stage haulage roadway is arranged below the bottom pillar, and the lower - stage haulage roadway is arranged along the ore vein. An upper - stage return airway using the upper - stage cross - vein haulage roadway for ore block stoping and ventilation is arranged above the top pillar; c. Stope layout: Each ore block is divided into several stopes perpendicular to the strike of the ore body, and multiple regular room pillars are left in each stope; Step 2: Development and cutting d. Cutting and haulage drift: Cut the lower - stage haulage roadway, stage return airway and stage haulage roadway according to step b. The lower - stage haulage roadway, upper - stage return airway and stage haulage roadway are all arranged in the footwall rock stratum along the ore body strike and cut along the ore body strike; e. Cutting stoping heading: In step c, a stoping heading is cut between two adjacent stopes. The upper end of the stoping heading communicates with the upper - stage return airway, and the lower end of the stoping heading communicates with the lower - stage haulage roadway. The cross - section of the stoping heading is not less than the minimum operating space of the equipment to ensure that the small - scale load - haul - dump can be turned around normally. The ore block is divided into multiple strips through the stoping heading; f. Cutting undercut drift: After leaving a bottom pillar at the lower part of the ore block, a cutting drift is driven along the strike of the ore body to form a cutting drift. The cross - section of the undercut drift is not less than the minimum operating space of the equipment, and the cutting drift is extended to both sides of the ore body to form an undercut space; Step 3: Stoping: The overall mining sequence in the panel is retreating stoping, and each strip in the ore block is mined along the reverse dip of the ore body; g. When the thickness of the ore body is less than 0.8 m, people cannot stand and equipment cannot enter the stope. During stoping, it is mined in two steps first. There is lower surrounding rock at the lower part of the ore body. First, the lower surrounding rock is mined. When mining the surrounding rock, the lower part is 5 - 6 m ahead of the inclined ore body, and the thickness of the mined surrounding rock is 1.5 - 2 m; After the surrounding rock collapses, the surrounding rock is directly cleared by a load - haul - dump or a mucking machine, and the cleared space is used as the ore - drawing space for the next - step ore mining; Stoping sequence: The stoping face is advanced in the reverse dip direction, that is, mined from the stoping heading to both sides of the stope, and then advanced in the reverse dip direction from bottom to top; h. After the surrounding rock is cleared, the ore body is mined. After the ore body collapses, it is transported out by a load - haul - dump; When mining the ore body, the depth of the blast holes needs to be controlled to avoid damaging the roof; Blasting hole - pattern parameters: The hole spacing in the ore vein is 0.4 - 1.0 m, and the hole spacing in the surrounding rock is 0.6 - 1.2 m; Blasting: The depth of the blast holes is controlled at 1.2 - 1.8 m; The charging length accounts for 2 / 3 of the blast - hole depth. After charging, stemming is blocked at the hole mouth, and the stemming length is greater than 100 mm; Emulsion explosive is used for blasting; It is detonated by non - electric detonator millisecond - delay detonators and initiated by an electronic initiator; Step 4: Mucking and ore drawing Both ore extraction and mucking use 0.6m 3 type internal combustion load-haul-dump (LHD) machines or mucking loaders to separately load the caved surrounding rock and ore into small trackless mining trucks in batches, and then directly transport them away along the stoping drift and the level haulage roadway.

2. The mechanized room-and-pillar mining method for gently inclined thin to extremely thin veins of precious metals according to claim 1, characterized in that, In step b, the height of the ore block in the same stage is 20 - 30 m, the width of the ore block is 50 m, the width of the stope is 12.5 m, the width of the continuous isolation interval pillar is not less than 8 m, the width of the top pillar is 4 m, and the width of the bottom pillar is 4 m.

3. The mechanized room-and-pillar mining method for gently inclined thin to extremely thin veins of precious metals according to claim 1, characterized in that, In step c, the length and width of the room pillar are 2.0×3.0 m.

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