RU2131035C1 - Method of placer deposit development - Google Patents

Abstract

FIELD: methods of mining of mineral resources occurring in beach zone adjoining the coastline; applicable in mining of placer deposits of shelf. SUBSTANCE: method consists in that placer deposit is developed by opencasting with mining equipment located on land. Placer development includes excavation of narrow trenches with their longitudinal axes located along direction of movement of surf waves. Preserved between water edge and nearest trench end is coffer which is crossed after trench excavation by water supply ditch whose depth is less than that of trench and at the level of water edge, it equals zero. Distance from water edge to the other end of trench corresponds to position of maximum run up of wave surf on beach during storm gales. Trench end facing water edge may be reinforced by seacoast wall. EFFECT: possibility of self-repair of biocenosis of beach zone with reduced technogenic effect on water medium in development of placer deposit. 4 cl, 3 dwg

Description

 The invention relates to the development of alluvial deposits of the shelf, and more specifically to the development of reserves lying in the beach area, directly adjacent to the coastline.

 There is a known method of developing a placer, including the use of a floating production unit (for example, dredge), which involves moving the production face from the water edge along the mineral mass with the simultaneous formation of a trench (pit) that allows the pontoon of the floating production unit to be moved (see the Handbook for the development of placers. Under the general editorship of V.P. Berezin, V.G. Berezin, V.G. Leshkov, L.P. Matsuev, S.V. Potemkin, M .: Nedra, 1973, p. 253-257, Fig. 65) .

 However, this technical solution does not ensure the conservation of the biocenosis of the worked out beach area, leads to siltation and cloudiness of the water area within which the development is being carried out, and significantly depends on weather conditions.

 There is also a known method of developing a placer, including the extraction of placer material by open pit mining based on land (see the book by V. B. Dobretsov, Development of shelf mineral resources, M .: Nedra, 1980, 1980, pp. 219-221, Fig. 71 , a).

 The disadvantage of this technical solution is the clouding of the water area. within the limits of which development is underway, since there is free communication of the aquatic environment with all sections of the working face, in addition, the gross principle of the extraction of placer material makes it difficult to restore the biocenosis of the beach area in its worked out areas.

 The problem to which the claimed invention is directed is expressed in providing the possibility of self-healing of the biocenosis of the beach area while reducing the industrial impact on the aquatic environment during development.

 The technical result obtained when solving the problem is expressed in reducing the turbidity of the water area to the level corresponding to the natural one, in addition, self-reclamation of the beach surface due to the work of the surf and the restoration of the placer due to the filling of trenches with material transported by the surf excite is ensured.

 To achieve this goal, the method of developing the placer, including the extraction of the placer material by open pit mining based on land, differs in that the placer is mined in narrow trenches that are positioned so that their longitudinal axis is along the direction of movement of the breaking waves, while between the edge of water and the trench end closest to it retain a bridge, which, after excavation is completed, the trenches are crossed by a water supply ditch, the depth of which is less than the depth of the trench, in addition , at the level of the water edge, the depth of the water supply ditch is zero.

 In addition, the removal of the second end of the trench from the water edge corresponds to the position of the maximum range of run-up to the beach of the surf in the period of the most severe storms.

 In addition, the distance between adjacent trenches should exceed the frequency of dividing the doubled depth of the trench by the tangent of the slope of the placer material, subject to its maximum mobility.

 In addition, the end face of the trench facing the coastline is reinforced with a vertical sheet pile wall.

 A comparative analysis of the features of the claimed solution with the signs of the prototype and analogues indicates the conformity of the claimed solution to the criterion of "novelty."

 The features of the characterizing part of the claims solve the following functional tasks.

 Sign. . . “placer mining is carried out in narrow trenches” provides the possibility of partial self-healing of the mine workings due to the collapse (shift) of the sides of the trenches themselves, i.e. thereby partial filling of the lower trench horizons with placer material not devoid of biocenosis.

 Sign. .. "which (ie, trenches) are positioned so that their longitudinal axis is located along the direction of movement of the breaking waves," reduces the resistance of the trench cavity to the movement of the water mass and, thereby, increases the transport range of solid material suspended in water and the completeness of filling the trench (in the process of its filling, self-healing).

 The sign ... "between the edge of the water and the end face closest to it, the trenches retain a bridge," simplifies the organization of work and eliminates the pollution of the water area during the treatment works.

 Sign. . . "which, after the excavation is completed, the trenches are crossed by a water supply ditch, the depth of which is less than the depth of the trench" provides the possibility of self-healing of the trench with solid material transported by water and supplied in the sides of the trench, while restricting the return of solid material from the trench with flooded water.

 Sign. . . "at the level of the water edge, the depth of the water supply ditch is zero" excludes the constant connection of the trench with the water area.

 The sign of the second claim determines the length of the trench, which ensures the full restoration of the beach during one annual cycle.

 The feature of the third claim determines the size of the pillar left between the trenches, which ensures self-healing of the placer at the locations of the trenches when using material transport with breaking waves without using material transfer by wind force (in which lighter empty rocks are transported first).

 The sign of the fourth paragraph of the claims ensures the stability of the end face of the trench facing the water area throughout the process of filling (washing) the trench and, thereby, maintaining the possibility of its operation in a mode similar to the operation mode of the stencil of the enrichment lock for solid materials suspended in volumes of water, returning after coasting.

 In FIG. 1 shows a plan view of a worked out section of a beach; in FIG. 2 shows a cross section through a system of trenches; in FIG. 3 shows a longitudinal vertical section through the trench at the initial stage of its erosion.

 The drawings show the water area 1, coastline 2, direction 3 of the movement of the surf waves, trenches 4, washed trenches 5, design contour 6 trenches, water supply ditch 7, border 8 of the maximum range of run-up to the beach 9 of the wave surf during the period of the most severe storms.

 The claimed method of developing a placer is carried out in the following order.

 In a known manner, the parameters of the occurrence of the placer and the hydrogeological parameters of the section of the beach 9 planned for mining (direction 3 of the movement of the breaking waves and the position of the border 8 of the maximum range of the run up to the beach 9 of the wave surf during the storms of greatest strength). In the case of significant in magnitude (more than 45 degrees) seasonal changes in the direction 3 of the movement of the surf waves, respectively, the position of the longitudinal axes of the trenches is changed 4. The depth of the trenches is determined from the condition of ensuring the maximum completeness of the extraction of the placer, taking into account the technical capabilities of the equipment involved in the treatment works. As coastline 2, it is advisable to use the boundaries of water area 1 at high tide.

 The most preferred set of equipment includes an excavator and a dump truck.

 Work starts from border 8 and moves the front of work towards coastline 2, along the direction. The extraction of the placer material with the formation of a trench 4 is carried out until the surface of the beach 9 allows free movement of equipment, or until it remains small (about 5 m, depending on the degree of inclination of the beach surface) between the corresponding end of the trench 4 and coastline 2. After that, the pillar is crossed by a water supply ditch 7, which has a variable depth (from 0 at the level of coastline 2 to a maximum at the contact with trench 4). At the same time, the maximum depth of the ditch 7 is less than the depth of the trench 4. Since the stability of the end face of the trench 4 closest to the coastline 2 is usually high, to maintain its shape (a ledge that holds in the trench 4 suspended solid parts falling into it with the breaking wave ) it is advisable to use reinforcing elements 10 of the type of metal sheets (tongue and groove) clogged in the end of the trench 4, as shown in FIG. 3.

 Further, departing from the formed trench by a distance L> 2h / tan α (where h is the depth of the trench, angle α is the angle of repose of the placer material, provided its maximum mobility (i.e., in the wet state), lay a new trench 4 within design contour 6 trenches, and so on, until the full development of the site planned for development.

 After the connection of trench 4 with water area 1, the breaking waves are swallowed into the trench, carrying with them suspended solid material.

 Water entering the trench. it washes away its sides, which leads to their collapse and partial filling. Thus, the material from the untouched massif preserving the biocenosis falls to the bottom of the trench 4, which facilitates the penetration of the objects of the biocenosis into the entire thickness of the beach 9.

 If there are 1 unburied placers at the bottom of the water area, the material of the latter is carried away by the breaking waves and, when suspended, enters trench 4. The largest and heaviest particles fall in the direct section of the movement of the breaking wave. Smaller fractions, which did not have time to precipitate in the reverse section of the wave motion, fall into the vortex formed at the wall 10 and fall to the bottom of the trench or the material of its collapsed sides. Then everything repeats. After washing the trench 4, the wall 10 is removed (by pulling) from the sand and reused. Small in volume excavations at the site of the trenches “heal” during the period of the most severe (usually autumn) storms. Thus, for a cycle including a period of time between periods of storms of the greatest strength, the restoration of the beach placer and the biocenosis of the beach is ensured. After the specified period, the treatment work on this section of the beach is resumed, while it is advisable to place the trenches 4 in the pillars left between the trenches 4 in the period of the previous mining.

Claims (4)

 1. The method of developing the placer, including the extraction of the placer material in an open way based on mining equipment on land, characterized in that the placer is mined in narrow trenches that are positioned so that their longitudinal axis is located along the direction of movement of the surf waves, while between the edge of the water and the trench closest to its end retains a lintel, which, after completion of excavation, the trenches intersect with a water supply ditch, the depth of which is less than the depth of the trench, in addition, at the level of the water edge, the depth the gutter is zero.  2. The method according to claim 1, characterized in that the removal from the water edge of the second end of the trench corresponds to the position of the maximum range of the run up to the beach of the wave surf during the storms of greatest strength.  3. The method according to claim 1, characterized in that the distance between adjacent trenches should exceed the quotient of dividing the doubled depth of the trench by the tangent of the slope of the placer material, subject to its maximum mobility.  4. The method according to claim 1, characterized in that the end face of the trench facing the coastline is strengthened with a vertical sheet pile wall.

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