Prospecting equipment

Abstract

A portable prospecting apparatus for wet placer mining, the apparatus including: a sluice box having a base and a center sluice panel for receiving and classifying a charge of placer material under influence of a fluid flow; and a buoyancy module coupled to the sluice box base, the buoyancy module reconfigurable between i) a first transport configuration to facilitate carrying of the sluice box, and ii) a second operational configuration for floatably supporting the sluice box on or above a surface of a body of water.

Description

PROSPECTING EQUIPMENTField

[0001] The present invention relates generally to prospecting equipment. More particularly, the present invention relates to a portable prospecting apparatus for use in wet placer mining. Such equipment typically referred to as a sluice box.Background

[0002] Wet placer mining is a method utilising water and gravity to separate or ‘classify’ mineral particulate obtained from ‘placer deposits’ (as they are known) based on size and specific gravity. A sluice box is typically used to channel a charge of placer ground along a flow path in the presence of a fluid flow (such as running water) to extract the desired minerals. Wet placer mining is often conducted in remote locations thereby requiring the sluice box to be transported to the designated mining site.

[0003] River sluices, which are commonly used for various purposes such as gold mining and sediment collection, often present a challenge due to their size and immobility. They are typically large and bulky, making them cumbersome to transport and set up.

[0004] River dredging is also a widely-used technique for riverbed excavation, often involving motorized equipment. However, the legality of river dredging varies from one region to another and is restricted in many areas due to environmental concerns. Existing river dredging and sluicing methods can be physically demanding and labour-intensive.

[0005] There is a need for an apparatus that is low effort to operate and user-friendly making it accessible to a wider audience, including individuals who might not have the physical strength or expertise to operate traditional river sluices or motorized dredging equipment.

[0006] There is also a need to provide an apparatus that is non-motorized, which sets it apart as a more environmentally friendly option and easier to transport to remote locations. This would also make the apparatus legal to use in a broader range of locations, eliminating the hassles associated with regulatory restrictions. Moreover, its non-motorized design contributes to reduced environmental impact, making it a responsible choice for those conscious of ecologicalconsiderations. The portability, mobility would allow movement along a river with ease, adapting to a prospectors needs. This mobility offers convenience and flexibility that existing devices lack.Summary of Invention

[0007] It is an object of the present invention to substantially overcome, or at least ameliorate, at least one drawback of present arrangements, for example at least one of the above drawbacks.

[0008] In an embodiment, there is disclosed a portable prospecting apparatus for wet placer mining, the apparatus including:

[0009] a sluice box having a base and a center sluice panel for receiving and classifying a charge of placer material under influence of a fluid flow; and

[0010] a buoyancy module coupled to the sluice box base, the buoyancy module reconfigurable between i) a first transport configuration to facilitate carrying of the sluice box, and ii) a second operational configuration for floatably supporting the sluice box on or above a surface of a body of water.

[0011] Preferably, the buoyancy module includes at least one carry strap to permit wearing of the buoyancy module when the buoyancy module is in the first transport configuration.

[0012] Preferably, including at least one carry strap is in the form of a shoulder strap for securing over a shoulder of a user.

[0013] Preferably, including a pair of shoulder straps to configure the buoyancy module to be worn as a backpack.

[0014] Preferably, the buoyancy module includes a body to be immersed in the body of water to provide a buoyancy force when the buoyancy module is in the second operational configuration.

[0015] Preferably, wherein the body includes:a hollow interior; and a closable opening fluidly communicating with the interior to permit entry or exit of a fluid with respect to the interior for ballasting the buoyancy module.

[0016] Preferably, wherein the body has an underside for planing or otherwise submersing below the surface of the body of water.

[0017] Preferably, wherein the underside includes a surface profile to vary the buoyancy force.

[0018] Preferably, the surface profile is a corrugated profile.

[0019] Preferably, the body is of a generally board-like configuration.

[0020] Preferably, further comprising an accessory operatively associated with the sluice box when the buoyancy module is in the second operational configuration.

[0021] Preferably, the body includes an attachment point for releasably holding the accessory when the buoyancy module is in the first transport configuration.

[0022] Preferably, the accessory is selected from the group consisting of a dredge discharge hose, a dredge suction nozzle, and a hand-operated pump.

[0023] Preferably, including a mat to catch target minerals.

[0024] Preferably, the center sluice is adjustable between 2 and 12 degrees from the base.

[0025] Preferably, including a crash box to inhibit placer material from returning upstream.Brief Description of Drawings

[0028] Exemplary embodiments of the present disclosure will now be described, by way of examples only, with reference to the accompanying description and drawings in which:

[0029] FIG. 1 is a perspective view of a portable prospecting apparatus according to a first embodiment;

[0030] FIG. 2 is a top perspective view of a sluice box of the apparatus of FIG. 1;

[0031] FIG. 3 is a perspective view of a sluice bed of the apparatus of FIG. 1;

[0032] FIG. 4 is a bottom perspective view of the sluice box of FIG. 2;

[0033] FIG. 5 is a side view of the sluice box of FIG. 2, with hidden details shown in dashed lines;

[0034] FIG. 6 is a front view of the sluice box of FIG. 2;

[0035] FIG. 7 is a top perspective view of a buoyancy module (float) of the apparatus of FIG. 1;

[0036] FIG. 8 is a rear view of the buoyancy module of FIG. 7;

[0037] FIG. 9 is a simplified illustration of a portable prospecting apparatus according to a second embodiment;

[0038] FIG. 10 is a simplified sketch of the apparatus of FIG. 9, shown with shoulder straps of the buoyancy module;

[0039] FIG. 11 is a perspective view of a portable prospecting apparatus according to a third embodiment;

[0040] FIG 12 is a top view of the apparatus of FIG. 11;

[0041] FIG 13 is a bottom view of the apparatus of FIG. 11;

[0042] FIG 14 is a front view of the apparatus of FIG. 11;

[0043] FIG 15 is a back view of the apparatus of FIG. 11;

[0044] FIG 16 is a first side view of the apparatus of FIG. 11;

[0045] FIG 17 is a second side view of the apparatus of FIG. 11 and;

[0046] FIG 18 shows a rendered view of the apparatus of FIG. 11 with the hand pump.Description of Embodiments

[0047] Referring firstly to FIG. 1 of the accompanying drawings there is depicted a portable prospecting apparatus 100 according to a first embodiment. The apparatus 100 is primarily configured for use in recovery of precious minerals and metals, preferably gold, from a wet placer deposit such as an alluvial or stream placer. FIGS. 9 and 10 show an apparatus 200 according to a second embodiment. Features of the apparatus 200 that are equivalent to those of the apparatus 100 are provided with the same reference numeral to that of the first embodiment, increased by 100. For features that are equivalent between the apparatus 100 of the first embodiment and the apparatus 200 of the second embodiment, it will be appreciated that the below description of these features in relation to the apparatus 100 is also applicable to the corresponding equivalent features found in the apparatus 200. A similar comment can be and in respect of the third embodiment shown in FIG 11.

[0048] With particular reference to FIGS. 2 and 4 to 6, the apparatus 100 includes a sluice box 102 for receiving and classifying a charge of placer material under influence of a fluid flow such as running water. The sluice box 102 has a body 104 including a base 106, a pair of side walls 108, an upstream wall 110 and a downstream wall 112. The base 106 is generally rectilinear and extends longitudinally between the upstream and downstream walls 110, 112. Each of the side walls 108 extends upwardly and laterally with respect to the base 106 so that the body 104 has a substantially U-shaped transverse cross-sectional configuration between the upstream and downstream walls 110, 112. The base 106 has a width defined as the distance between the pair of side walls 108, and a length defined as the distance between the upstream and downstream walls 110, 112. In some embodiments, the base 106 has a length-to- width ratio in the range of about 2.0: 1 to 2.5: 1.

[0049] The body 104 further includes a substantially flat underside 114 (FIG. 4) being of a generally rectangular configuration. Each of the side walls 108 has a height defined as the distance from the underside 114 to an upper surface 108a of the side wall 108. The height of each of the side walls 108 reduces in the direction of extension of the base 106 such that the pair of side walls 108 taper in a direction from the upstream wall 110 towards the downstream wall 112. In this way, each of the side walls 108 is of a generally trapezoidal configuration having amaximum height in the range of about 160 mm to 190 mm and a minimum height in the range of about 90 mm to 120 mm. In the illustrated embodiment, the upstream wall 110 extends perpendicularly from the underside 114 and past the upper surface 108a of each of the side walls 108, whilst the downstream wall 112 extends perpendicularly from the underside 114 and terminates short of the upper surface 108a of each of the side walls 108.

[0050] The base 106 includes a top surface 106a which is inclined relative to the underside 114 to provide a slope or gradient from the upstream wall 110 to the downstream wall 112. The top surface 106a of the base 106 is inclined at an angle a (FIG. 5) in the range of about 5 degrees and 30 degrees. Together, the top surface 106a of the base 106, the pair of side walls 108 and the upstream and downstream walls 110, 112 partially surround an interior or U-shaped channel 116 of the sluice box 102. The angle a can be adjusted by the user as required.

[0051] As shown in FIG. 3, the apparatus 100 further includes a sluice bed 118 for releasably locating within the channel 116 of the sluice box 102. The sluice bed 118 is sized to rest on the top surface 106a of the base 106 of the sluice box 102 in use. The sluice bed 118 is dimensioned for supporting conformity with the channel 116 of the sluice box 102 to minimise lateral and axial movement of the sluice bed 118 with respect to the sluice box 102, at least beyond minor movement associated with the free play of the sluice bed 118 within the slightly broader dimensions of the channel 116 of the sluice box 102. In this way, the sluice bed 118 is confined to the channel 116 of the sluice box 102 during use.

[0052] The sluice bed 118 includes a pair of transversely projecting ribs or rails 120 integrally formed on an underside 118a of the sluice bed 118. In use, the rails 120 releasably engage complementary-shaped channels or grooves 122 formed through the top surface 106a of the base 106 to further mitigate relative movement between the sluice bed 118 and the sluice box 102. In other embodiments, the rails 120 may have different forms or shapes, be in any number and / or formed separately but coupled to the sluice bed 118. Optionally, the sluice box 102 may include one or more locating features (such as a projection or post 124) extending from the top surface 106a of the base 106 for locating with a complementary-shaped cut-out 126 formed through the sluice bed 118 (such as at one or more comers thereof) to aid in seating the sluice bed 118 with respect to the top surface 106a of the base 106 of the sluice box 102.

[0053] Optionally, a finger hole 128 may be formed partially through the downstream wall 112 to aid in removing the sluice bed 118 from the sluice box 102. In other embodiments, the downstream wall 112 or the sluice bed 118 may include a knob or other projection to facilitate removal of the sluice bed 118 from the sluice box 102.

[0054] The sluice bed 118, together with the pair of side walls 108, defines a channel flow path for receiving and confining a charge of placer material (not shown) under influence of a flow of water in a flow direction A (FIG. 1) from the upstream wall 110 towards the downstream wall 112. The sluice bed 118 preferably includes a perforated classifier 130 to convey the slurry mixture of water and placer material in the flow direction A, permitting gravity to separate particles from the slurry mixture. In some embodiments, the classifier 130 may be formed of aluminium, plastics or composite materials.

[0055] The sluice bed 118 has a thickness which is the same or slightly greater than a height of the downstream wall 112 above the base 106 to permit the flow of water over the downstream wall 112 to exit the channel 116 of the sluice box 102.

[0056] With particular reference to FIGS. 7 and 8, the apparatus 100 further includes a buoyancy module 134 (float) to provide a buoyancy force when immersed in a body of water such as a stream or river of the wet placer deposit. The buoyancy module 134 includes a generally planar module body 136 extending in a widthwise direction to provide an overall width and a lengthwise direction to provide an overall length. In a preferred embodiment, the width is in the range of about 400 mm to 800 mm, and the length is in the range of about 1 m to 1.4 m. The module body 136 has a thickness which is substantially less than the width or length of the module body 136. In this way, the module body 136 is generally board-like having a narrow rectangular configuration in longitudinal and transverse cross-sections. In other embodiments, the shape of the module body may be varied. For example, the module body may be circular, hexagonal or other polygonal in configuration. In the embodiment depicted, the module body 136 has a pair of filleted comers at one end, and a pair of chamfered corners at the other end to streamline the profile of the module body 136.

[0057] The module body 136 is preferably comprised of plastics but may alternatively be formed of other lightweight materials such as aluminium, natural fiber, foam, fiberglass or other composites, or combinations thereof. The rigidity, durability and / or mechanical strength of themodule body 136 may be varied via one or more material additives or choice of material composition. The module 136 may also be of any particular shape to suit a corresponding base. See for example, FIG 18.

[0058] In the embodiment depicted in FIGS. 9 and 10, the module body 236 may be in the form of a shell providing a hollow interior such that the module body 236 is configured as a ballast to provide stability to the buoyancy module. In this way, an amount of water may be taken into or ejected from the hollow interior via a closable opening 237 formed through a wall of the module body 236 depending on the degree of stability required.

[0059] As shown in FIG. 7, a recess 138 is formed in an upper surface 140 of the module body 136 and is shaped for supporting conformity with the underside 114 of the sluice box 102 for coupling the sluice box 102 to the buoyancy module 134. In other embodiments, the sluice box 102 is integrally formed with the buoyancy module 134. In some embodiments, the sluice box 102 may be detachably coupled to the buoyancy module 134. In other embodiments, the sluice box 102 may be pivotally or slidably attached to the buoyancy module 134 to vary the inclination or positioning of the sluice bed 118 with respect to a surface of the body of water.

[0060] In use, the module body 136 displaces a volume of water such that the weight of the water displaced by the module body 136 is equal to or greater than the total weight of the apparatus 100, thereby causing the apparatus 100 to float. In particular, since the sluice box 102 is coupled to the upper surface 140 of the module body 136, the buoyancy module 134 is configured to floatably support the sluice box 102 on or above the surface of the body of water.

[0061] The module body 136 has an underside 136a for submersing below the surface of the body of water to a floating depth, where the floating depth is defined as the distance between the surface of the body of water and the underside 136a of the module body 136. The underside 136a of the module body 136 may be modified to include one or more surface profiles or protrusions to vary the volume of water displaced and thereby vary the buoyancy force and the floating depth. In the embodiment depicted, the underside 136a of the module body 136 includes a corrugated profile having a repeating pattern of longitudinally extending rounded ridges and troughs.

[0062] In the illustrated embodiment, the buoyancy module 134 includes a handle 142 for a user to grasp with one hand to permit carrying of the buoyancy module 134 in a convenient manner.The handle 142 also facilitates stabilising, positioning or manoeuvring of the buoyancy module 134, and thus the sluice box 102 and the sluice bed 118, during use. In the embodiment depicted, the handle 142 is formed by removing a section of material from the module body 136 to create an elongate hole 144 and an adjacent grip portion 146. The elongate hole 144 is sized to permit fingers of the user’s hand to pass therethrough to enable the grip portion 146 to be gripped.

[0063] Preferably, the buoyancy module 134 further includes a pair of carry straps (labelled with reference numeral 248 in FIG. 10 for the apparatus 200 of the second embodiment and 328 in FIG 11 for the third embodiment) for attachment to the underside 136a of the module body 136 via respective anchor points 150. Although, the number of carry straps 248 may be varied. In the second embodiment depicted, the carry straps 248 are in the form of shoulder straps 248 configured to be restrained or otherwise secured over the user’s shoulders for carrying the buoyancy module 134, and thus the sluice box 102 and, optionally, the sluice bed 118, on the user’s back or torso in a similar manner to carrying a backpack. In this way, the shoulder straps 248 and / or the underside 136a of the module body 136 may be padded to provide comfort to the user when the buoyancy module 134 is worn. The buoyancy module 134 may alternatively be worn around the user’s neck, waist, arm or otherwise carried in any convenient manner. Optionally, the shoulder straps 248 may be detachable from the module body 136 so that the shoulder straps 248 may be removed prior to immersing the buoyancy module 134 in the body of water.

[0064] In this way, the buoyancy module 134 is readily and conveniently interchangeable or reconfigurable between a first transport configuration to facilitate carrying of the apparatus 100 and a second operational configuration for floatably supporting the sluice box 102 on or above the surface of the body of water for convenient use.

[0065] The buoyancy module 134 further includes a plurality of auxiliary attachment points in the form of retaining clips or clasps 152 (FIG. 1) for releasable or detachably holding or storing one or more accessories to be used in conjunction with the apparatus 100. A portion of the clasps 152 may be integrally formed or otherwise coupled to the module body 136. In the embodiment depicted in FIGS. 9 and 10, the module body 236 may include one or more slots or compartments 254 for retaining the one or more accessories therein. In some embodiments, the one or more accessories may include: i) a dredge discharge hose 256 configured to dischargematerial onto the sluice bed 118; ii) a dredge suction nozzle (not shown) fluidly connected to the dredge discharge hose 256 and having an opening for sucking therethrough material from the body of water; and iii) a hand-operated pump 258 for supplying high pressure water to the dredge suction nozzle and / or the dredge discharge hose 256.

[0066] A method of wet placer mining utilizing the apparatus 100 will now be described. Initially, the buoyancy module 134 is in the first transport configuration thereby permitting the apparatus 100 to be conveniently carried via the shoulder straps 248, for example, to the designated wet placer deposit. The buoyancy module 134 is then reconfigured into the second operational configuration by simply planing or otherwise submersing the underside 136a of the module body 136 below the surface of the body of water. In this configuration, the sluice box 102 and the sluice bed 118 are floatably supported on or above the surface of the body of water for convenient use.

[0067] The charge of placer material is then introduced under influence of a fluid flow (such as diverted from a nearby moving water source via the dredge discharge hose 256 and / or supplied via the dredge suction nozzle or the hand pump 258) onto the sluice bed 118 adjacent the upstream wall 110 for flow along the channel flow path in the flow direction A, whereby the classifier 130 separates placer material based on size and specific gravity. To facilitate accessibility, the dredge discharge hose 256 may be releasably connected to the sluice box 102 via a through-hole 153 formed in the upstream wall 110. Following completion of the mining operation, the buoyancy module 134 may be reconfigured back into the first transport configuration by simply retrieving the apparatus 100 via the handle 142 and / or the shoulder straps 148.

[0068] A third embodiment is shown in Figures 11 to 17. A preferred method of construction of the apparatus 300 shown in Fig. 11 is now described by way of example. The apparatus 300 typically comes flat packed and includes a crash box sub-assembly 302 and a sluice box subassembly 304 and a flotation device 306 (buoyancy module).

[0069] In a first step, the crash box sub-assembly 302 (first sub-assembly) is assembled by connecting the crash box back 308, top cap 310, spacer piece top 312 using three M5 rivets 314 aligned through corresponding holes. The sluice box sub-assembly (second sub-assembly) 304 is then assembled using the side walls 316 attached uprightly to the base 317 using ten M5 rivets314 aligned through corresponding holes. The center sluice 318 is then inserted between the walls 316 and using 6 M5 rivets 314 secured to the walls 316. The first sub -assembly 302 is then fastened to the upstream end of the second sub-assembly 304 and secured together by way of six M5 rivets 314 through corresponding holes. A splash cap 320 is then added by way of four 25mm screws 320 and four corresponding wingnuts 320 aligned through corresponding holes. The wingnuts should face outwardly. A bottom lock 324 is then added by way of two 25mm screws 322 and two M5 wingnuts 322 aligned through corresponding holes. The back foam piece 326 (buoyancy module) can then be added to the base by way of straps 328 and the manual pump 330 added. The straps 328 can also include additional loops to permit the apparatus to be carried backpack style. The pump 330 can be connected to the apparatus 300 by way of connector 332 fastened to the top of the crash box sub assembly 302. The side walls 316 can also have slots 334 to allow excess water to flow easily away from the apparatus 300.

[0070] The apparatus 300 is preferably made out of high-quality durable materials such as marine grade aluminum and HDPE injection molding castings. Each of the metal components is preferably precision-engineered from 1.6mm thick aluminum sheeting, striking a balance between lightweight design and exceptional durability. The manufacturing process in a preferred form would involve laser cutting the sheets to shape, followed by precision bending and assembly. Miners moss matting 336 is preferably used as the matting in the sluice for efficient gold capture during the washout process. Recognizing the diverse preferences among prospectors for different matting types, ranging from astroturf to pattern-pressed options, flexibility should be prioritized to accommodate users' matting preferences. At the base of the sluice, a finger gap 338 facilitates the easy removal of the matting 336, ensuring convenient lifting while serving as a final barrier to capture any materials that may have washed over the matting.

[0071] Advantageously, the apparatus 300 provides adjustable angles of the center sluice 318, offering tilts at 3, 7, and 11 degrees. This feature allows for a customized water flow, catering to varying river conditions and individual preferences. Further, the crash box 302, prevents material splash-back and escape. The apparatus 300 is designed for user convenience, allowing for easy disassembly for maintenance or repair, eliminating the need for an entire device replacement. The entire sluice assembly weighs approximately 2 kilograms, ensuring a balance between portability and robust functionality.

[0072] In the preferred form, the center sluice can operate at multiple angles ranging from 2-13 degrees. This allows the user to set the speed of the water flow through the device to their preferred settings. This function is achieved preferably through a push-pull pin setup from the wall to center sluice components of the device.

[0073] Further advantageously, the present invention, at least in a preferred embodiment, provides a device that simplifies the gold prospecting process for finding alluvial gold. It offers flotation capabilities, ease of use, ergonomic design for comfort and mobility, durability and water resistance and enhanced mobility in challenging terrains, making it a game-changer for prospectors. It provides for a wider range of users than existing devices. The ease of use means that children through to the retirees can use it.Reference Numeral List100 apparatus of a first embodiment 200 apparatus of a second embodiment102 sluice box 202 sluice box of second embodiment104 body 234 buoyancy module of second106 base embodiment106a top surface of base 236 module body of second embodiment108 side walls 237 opening108a upper surface of side walls 248 carry strap s / shoulder straps110 upstream wall 254 compartments112 downstream wall 256 dredge discharge hose114 underside of body 258 hand pump116 channel of sluice box 300 apparatus of a third embodiment118 sluice bed 302 crash box sub-assembly118a underside of sluice bed 304 sluice box sub-assembly120 rails 306 flotation device122 grooves 308 crash box back124 post 310 top cap126 cut-out 312 spacer128 finger hole 314 rivets130 classifier 316 side walls134 buoyancy module 317 base136 module body 318 center sluice136a underside of module body 320 splash cap138 recess 322 screws / wingnut140 upper surface of module body 324 bottom lock142 handle 326 back foam144 hole 328 straps146 grip portion 330 pump150 anchor points 332 connector152 clasps 334 slots153 through-hole 336 matting338 finger gap

Claims

CLAIMS1. A portable prospecting apparatus for wet placer mining, the apparatus including: a sluice box having a base and a center sluice panel for receiving and classifying a charge of placer material under influence of a fluid flow; and a buoyancy module coupled to the sluice box base, the buoyancy module reconfigurable between i) a first transport configuration to facilitate carrying of the sluice box, and ii) a second operational configuration for floatably supporting the sluice box on or above a surface of a body of water.

2. The apparatus of claim 1, wherein the buoyancy module includes at least one carry strap to permit wearing of the buoyancy module when the buoyancy module is in the first transport configuration.

3. The apparatus of claim 2, wherein the at least one carry strap is in the form of a shoulder strap for securing over a shoulder of a user.

4. The apparatus of claim 3, wherein the buoyancy module includes a pair of shoulder straps to configure the buoyancy module to be worn as a backpack.

5. The apparatus of any one of the preceding claims, wherein the buoyancy module includes a body to be immersed in the body of water to provide a buoyancy force when the buoyancy module is in the second operational configuration.

6. The apparatus of claim 5, wherein the body includes: a hollow interior; and a closable opening fluidly communicating with the interior to permit entry or exit of a fluid with respect to the interior for ballasting the buoyancy module.

7. The apparatus of claim 5 or 6, wherein the body has an underside for planing or otherwise submersing below the surface of the body of water.

8. The apparatus of claim 7, wherein the underside includes a surface profile to vary the buoyancy force.

9. The apparatus of claim 8, wherein the surface profile is a corrugated profile.

10. The apparatus of any one of claims 5 to 9, wherein the body is of a generally board-like configuration.

11. The apparatus of any one of claims 5 to 10 further comprising an accessory operatively associated with the sluice box when the buoyancy module is in the second operational configuration.

12. The apparatus of claim 11, wherein the body includes an attachment point for releasably holding the accessory when the buoyancy module is in the first transport configuration.

13. The apparatus of claim 11 or 12, wherein the accessory is selected from the group consisting of a dredge discharge hose, a dredge suction nozzle, and a hand-operated pump.

14. The apparatus of anyone of the preceding claims, including a mat to catch target minerals.

15. The apparatus of anyone of the preceding claims, whereby the center sluice is adjustable between 2 and 12 degrees from the base.

16. The apparatus of anyone of the preceding claims, including a crash box to inhibit placer material from returning upstream.

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