The rougher bank of HTR separators produces a final concentrate, a middlings stream that is recycled to the HTR feed and a tailings stream sent to the HTR scavenger circuit. See also Section 6.27 for radial wells. Figure 25.2 shows the interpreted subsurface conditions encountered along the CKE alignment based on the borehole information. The tunnel gradient is slightly less than the groundwater gradient and much less than the topographical gradient; therefore the tunnel subsequently emerges above the water table and eventually at the ground surface where it acts as a canal to deliver the water where required. Alluvial deposit, Material deposited by rivers. a low triangular area of alluvial deposits where a river divides before entering a larger body of water placer an alluvial deposit that contains particles of some valuable mineral The extent of the bonding is such that it can not be crushed by figure-pressure. [3] Alluvium of Pliocene age occurs, for example, in parts of Idaho. Shallow alluvial deposits may be investigated using a combination of ‘horizontal profiling’ and ‘vertical electrical sounding’: Horizontal profiling examines the lateral distribution of electrical resistivity at relatively constant depths and is most effective when the lateral changes in resistivity are large; interpretations are qualitative and instrument precision need not be high unless they are calibrated by additional soundings. The patented Ranney well is an early form of collector well, usually made of cast iron and sunk in river bankside gravels or alluvial deposits fed from the river, with perforated collector tubes jacked or jetted out horizontally from the base in the most appropriate configuration, often parallel to the river. Cleaning of the gravity concentrate with HTR separators is preferred as relatively little material is pinned to the rotor in the high-tension treatment of the gravity concentrate (Fe-oxides are conductive). From the base of the caisson, collector pipes are laid out horizontally usually upstream, though sometimes across the stream bed or fanwise upstream. It is important to lay the collectors at sufficient depth to avoid their destruction during floods when some of the stream bed can mobilize into suspension. A known current is passed into the earth through the current electrodes A and B. M and N are the potential electrodes between which a potential difference is measured due to the current passed (Fig. Sediments that are formed or deposited in a perennial stream or river are typically not referred to as alluvial. Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... …in three types of deposits: alluvial gravels, glacial tills, and kimberlite pipes. Some textbooks use the term, “Fluvial deposits” for the same thing. The naturally bonded sands are, for example, Ipswich loam and Meringengden sand with AFS clay content of 13.6% and 7.4% respectively. Each rotor is 10 ft long with a roll diameter of 14 in. This article was most recently revised and updated by, https://www.britannica.com/science/alluvial-deposit. Alluvium (from the Latin alluvius, from alluere, "to wash against") is loose, unconsolidated (not cemented together into a solid rock) soil or sediment that has been eroded, reshaped by water in some form, and redeposited in a non-marine setting.