In the mountains of the United States, sluices transported logs from steep hillsides to downslope sawmill ponds or yarding areas. Nineteenth-century logging was traditionally a winter activity for men who spent summers working on farms. Where there were freezing nights, water might be applied to logging sluices every night so a fresh coating of slippery ice would reduce friction of logs placed in the sluice the following morning.[4]
Sluice boxes are often used in the recovery of black sands, gold, and other minerals from placer deposits during placer mining operations. They may be small-scale, as used in prospecting, or much larger, as in commercial operations, where the material is sometimes screened using a trommel, screening plant or sieve. Traditional sluices have transverse riffles over a carpet or rubber matting, which trap the heavy minerals, gemstones, and other valuable minerals. Since the early 2000s more miners and prospectors are relying on more modern and effective matting systems.[citation needed] The result is a concentrate which requires additional processing.
sluices
Nineteenth century gold miners used wooden sluices that were at least 12 feet long, but modern gold prospectors primarily use sluice boxes made of plastic or metal which are typically 24, 36 or 48 inches long and 6 to 10 inches wide. The idea is to position a sluice box in a running stream so that the water does the work-- separating the dirt and rocks away from the gold. Since gold is heavy, it will stay in the bottom of the sluice, trapped in the miner's moss.
A good rule of thumb is to set your sluice at a grade of one inch per foot of drop. At least start here, and adjust as needed. A steeper grade may result in all but the coarsest gold being carried away by the force of the water. The non-motorized sluices below are made by Jobe, Tee-Dee, Le Trap, RDH Prospecting, Gold Buddy and are all considered hand sluices. Click here for Power Sluices / Highbankers.
Pinched sluices have been used for heavy-mineral separations for centuries. In its elementary form, the pinched sluice is an inclined trough 2 to 3 feet long, narrowing from about 9 inches in width at the feed end to 1 inch at discharge. Feed consisting of 50-65% solids enters gently and stratifies as the particles flow through the sluice and crowd into the narrow discharge area. Heavy minerals migrate to the bottom, while lighter particles are forced to the top. This separation is inhibited at the walls of the sluice due to drag force. The resulting mineral bands are separated by splitters at the discharge end (Figure 15).
Pinched sluices are very simple devices. They are inexpensive to buy and run, and require little space. Pinched sluices and local variants are mainly used for separation of heavy-mineral sands in Florida and Australia. Models that treat ore material are also used. Recovery difficulties result from fluctuations in feed density or feed grade. A large number of pinched sluices are required for a high capacity operation, and a large amount of recirculation pumping is required for proper feed delivery. These drawbacks led to the development of the Reichert cone.
Urban river pollution is considered a 'necessary evil' consequence of disproportionate developmental expansion in metropolises. Unprecedented expansion and anthropic activities lead to the deterioration of urban rivers with municipal and industrial sewage. The construction of sluices is one of the irrefutable parts of the process. In order to prevent floods and drought, many cities build sluices and dams in rivers to balance water quantity in different seasons. To explore the change characteristics of the water quality in urban rivers after the construction of sluices and dams, the change in the total phosphorus (TP) and total nitrogen (TN) concentrations upstream and downstream of rivers was investigated under the condition of sluices closure in Wuxi. According to the results, when the sluices were closed, the pollutants of TP and TN would accumulate upstream in rivers, which caused the water quality in the upper reaches to be worse than that in the lower reaches. Specifically, the TN and TP concentrations downstream of urban rivers in Wuxi were approximately 14.42% and 13.80% lower than those upstream when the sluices were closed. Additionally, the water quality in urban rivers was usually better in summer and autumn than in the other seasons, showing obvious seasonality after the construction of the sluices. The research will provide a theoretical basis for future sluice operation and the water resources management of urban rivers.
Sluices are main flood control infrastructures in coastal areas, where soft rock and soft soil are widely distributed. In soft soil areas, the vertical displacement of sluice is common, which is the main factor affecting the sluice safety. So, it is very important for sluice safety control according to the prototypical observations on deformation. Considering some drawbacks of leveling, such as it can only provide a limited number of points and requires time-consuming field work, this paper evaluates the performance of Interferometric Synthetic Aperture Radar (InSAR)-based method in monitoring long-term vertical displacement deformations of sluices. Taking 12 sluices in Northern Jiangsu, China as an example, 129 Sentinel-1 C-band VV-polarizatio ascending SAR images that span the period from April 2015 to January 2020 were used to monitor their vertical displacement deformations. The leveling results are made to verify the accuracy and reliability of Permanent Scatterer InSAR (PSInSAR) method. The validation indicates good agreement between PSInSAR results and leveling results. Considering the higher accuracy of leveling, PSInSAR method is more suitable as an auxiliary technology besides leveling method to focus on the early warning of sluice deformation risk events.
Above are the results of unscrambling sluices. Using the word generator and word unscrambler for the letters S L U I C E S, we unscrambled the letters to create a list of all the words found in Scrabble, Words with Friends, and Text Twist. We found a total of 64 words by unscrambling the letters in sluices. Click these words to find out how many points they are worth, their definitions, and all the other words that can be made by unscrambling the letters from these words. If one or more words can be unscrambled with all the letters entered plus one new letter, then they will also be displayed.
Last September, Daniel Stapper of PACT facilitated the construction of three of our Popandson sluices in Abuja, Nigeria, along with a furnace, crucibles, and the tongs needed for direct smelting of gold ore concentrate. He was able to easily procure the materials in-country and the cost of production was around one-fifth the cost of fabrication in the United States. This demonstration proves that improved recovery technology can be easily created anywhere.
In calibrating sluices that meet the requirements of rating sections,the current-meter method is commonly used. It may also be practical tocalibrate the sluice with a temporary weir, provided sufficient fall isavailable. The calibration consists of measuring the discharge for variousdepths of flow in the sluice at a rating station and plotting the dischargesagainst depths. The channel should be of regular section and free fromdisturbance caused by upstream conditions such as bends, multiple gatesoperating at unbalanced openings, waves, and other distorting influences.
Many of the formerly gradual transitions between marine and freshwater habitats have been severely altered by man-made constructions. In the Netherlands, water managers are implementing numerous measures to decrease the negative effects of these barriers on fish migration (e.g. constructing fish passages). Adjusting sluice management to restore a salt water / fresh water gradient, however, is a novel way of accommodating fish migration. To effectively apply this measure, more knowledge is required on how fish migration is influenced by sluices.
At Spaarndam (the Netherlands), a complex of pumping stations and sluices separates salt water and fresh water. Within this complex, fish can either migrate into discharge channels towards pumping stations, or migrate into sluices and continue upstream. In spring 2014, we evaluated fish migration at the Spaarndam complex to determine where fish enter (i.e. into the sluices or discharge channels), and whether fish were able to pass the complex. A total of seventeen species were observed. The vast majority of individuals were juvenile Anguilla anguilla (elver). A marked difference within the complex was observed: when fresh water was discharged, the vast majority of elvers migrated towards the impassable pumping stations. Migrating elvers were almost absent in sluices. This was most likely due to the lack of an attraction flow at the sluices. In contrast, other species (e.g. pike-perch, bream and perch) used the sluices for migration utilizing openings in the sluice doors. 2ff7e9595c
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