Wet sieving

Particle Size. Wet sieve analyses are commonly used in the 20 )J.m (using microsieves) to 150 )J.m size range. Sizes in the 1—10 )J.m range are analyzed by light-transmission Hquid-phase sedimentation, laser beam diffraction, or potentiometric variation methods. Electron microscopy is the only rehable procedure for characterizing submicrometer particles. Scanning electron microscopy is useful for characterizing particle shape, and the relation of particle shape to slurry stabiUty. 

A preferable alternative is to use wet sieving (see below) as well as in instances where ag-... 

Analytical sieving may also be done with the solids in a liquid suspension. In this case, it is called wet sieving, and the suspension is transferred to the nested sieves and rinsed through with solvent. The suspended particles are captured on the sieves in the same manner as described above. 

Soil samples were wet sieved into (a) 2-4 mm, (b) 1-2 mm, (c) 0.5-1 mm, (d) 250-500 i m, (e) 125-250 am, (f) 63-125 j,m and (g) <63 j.m fractions. A ferruginous/magnetic fraction (m) was also prepared from the 2-4 mm fraction. Soil fractions were crushed, digested with HNO3/HCI/HF/HCIO4 and then analysed by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) for Al, Ca, Cu, Fe, K, Mn, Na, P, S and Zn. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used to determine Ag, As, Cd, Pb and Sb because of the lower detection limits by this method. The mineralogy of selected samples was determined by qualitative X-ray diffractometry. 

Wet Sieving by a Mechanical Flushing Procedure. The sieve residue is the portion of coarse particles that cannot be washed through a specified test sieve with water. The result depends on the mesh size of the sieve. For standards, see Table 1 ( Residue on sieve Mechanical method ). Apparatus Mocker s apparatus. 

Wet sieving method of sieving coal that uses water as a medium for facilitating segregation of a sample into particle size (ASTM D-4749). 

Dry sieveing is an alternative method if wet sieving (Section 3.2.3.1) cannot be used, as is the case of seasonal streams in Mediterranean countries. 

Wet sieving is recommended whenever it is possible. Instructions for sampling with wet sieving method are presented in section 3.2.3.1. If it is not possible to wet sieve the stream sediment sample in the field, the collected stream sediment material should be dry sieved. Instructions for sampling and dry sieving are given in section 3.2.3.2. 

The procedure for the selection of sample sites, recording their location on the field map, completion of field observation sheets, wearing of rubber gloves, etc. are the same as for the wet sieving sampling method (refer to Section 3.2.3.1). 

Since, water is not available to wet sieve the stream sediment to the required <0.150 mm fraction, collect a bulk composite sample from 5-10 points over adistance of 250-500 meters. The total dry weight of the composite sample (free of stones and other coarse grained material) should be about 5 kg to ensure that the required amount of 500 grams of analytical <0.150 mm material will be obtained after sieving at the domestic lab. 

Fig. 7. Wet sieving of a stream sediment sample (Photo Fiona Fordyce, BGS)...

Percent chrysotile asbestos in bulk samples may be measured by X-ray powder diffraction (NIOSH Method 9000, 1984) sample dust grinded under liquid N2 wet sieved through 10-mm sieve sieved material treated with 2-propanol agitated in an ultrasonic bath filtered on a silver filter measured by XRD, using a Cu target X-ray tube. 

Microcline, albite and labradorite were obtained from Ward s Canada Limited. Cleaved crystal fragments and 60 mesh-sized samples were ultrasonically cleaned prior to use. Powdered samples (particle size < 25 ym) were prepared by grinding in a tungsten carbide ball mill, wet-sieving and washing in water. 

Wanogho, S., Gettinby, G., Caddy, B., and Robertson, J. (1987b). Some factors affecting soil sieve analysis in forensic science 2 Wet sieving. Forensic Sci. Int. 33, 139-147. 

Further wet sieve <2000 pm sediment from as deep as possible within the stream bed, using the top sieve placed directly on the wooden pan. Copious amounts of water may be used to aid sieving at this stage. Once the wooden pan is almost full of <2000 pm material the panned heavy mineral concentrate is then collected using the following three stages ... 

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