WET SEPARATION

Low intensity magnetic separators are used to upgrade iron ores containing magnetite. Dry separators are used for coarse (up to 100 mm in size) ore and wet separators are used for fine (—9.5 mm) ores. 

High intensity magnetic separators are used to upgrade iron ores containing hematite or ilmenite. Dry separators require ore that is finely sized and bone dry. They are dusty, expensive, and have a low capacity. Wet separators have larger capacity, are less dusty and can handle ore sizes up to 1 mm. 

The process developed at CPRR is said to be similar in its layout to those used in private industry. Most plastic reclamation systems are designed to work with rigid containers, such as PET beverage bottles, and HDPE milk or household product containers, because they are currently the easiest postconsumer items to collect and sort. PET beverage bottles are actually not one, but several materials a PET body (clear or green), a pigmented high-density polyethylene (HDPE) base cup, aluminum cap, label, and adhesives. To separate these components, either a dry or wet separation method based on one or more of the different physical properties of the materials can be used. 

The wet separation process, in which the pigment-containing gas mixture (Cl2, 02, and C02) is quenched in water, has not become established. 

The olefin 3,3-dimethyl-l-butene (III) was studied since it gave almost exclusively the expected product 3,3-dimethyl-l-buten-2-yl acetate (VII) with only traces of ketone or 3,3-dimethyl-l-buten-l-yl acetate. With a single product the test of material balance was simplified since it was possible to run a blank on the wet separation and then check the yield of VII by isotope dilution using (CH3)3CC(OCOCD3)=CH2. Experiments with III are not complicated by isomerization or allylic palladium complex formation and are unlikely to involve free radical reactions. 

Analyses. Samples of reaction mixtures were frozen and sublimed into the vacuum line (10-6 mm Hg). The vapor was passed through a wide-bore U-trap at —45°C which collected acetic acid and volatile oxidation products and allowed any unreacted hexenes to pass. After further fractional condensation the hexene was transferred to a graduated tube to measure the volume and was finally analyzed by GLC using a 12 meter X 6 mm column packed with polypropylene glycol LB-550-X on Chromosorb W. The sublimation residue was analyzed by IR spectroscopy while the acetic acid condensate was subjected to a wet separation (5, 15) to recover the oxidation products for GLC analysis. 

Zheng, G.H. and Bhatty, R.S. 1998. Enzyme-assisted wet separation of starch from other seed components of hull-less barley. Cereal Chem. 75 247-250. 

The preferred type of flow concerning the operation of fouling-sensitive reactions is the stable Y-type jet [53], Mixing is here performed at a position distant from the mixer outlets. Since the mixer surface ideally is only wetted separately by the reactant solutions, the precipitation is kept a safe distance from the micro channels. With regard to fouling, any operation resulting in direct merging of the streams is not... 

Heavy media separation is a wet separation method and, as such, has been applied in a limited extension in solid-waste processing. It has been mostly used to separate aluminum, which is collected to the light fraction, from other materials in car recycling. 

A wet separation of blopolymer from broth would be particularly advantageous if blopolymer were produced near the site of use. Not only would the expense of alcohol precipitation be bypassed, but also the difficult redispersion of dry blopolymer into aqueous solutions and removal of cell debris and poorly dispersed polymer fragments, etc., which would plug the pores of the formation. 

Disperse particulate solids in suitable liquid (wet separation). 

The pressure losses of electric separators in comparison with the other types are very low, ranging between 60 and 250 Pa. A good separation efficiency with saving optimum operation conditions may be achieved in mechanical dry separators as well as wet separators at pressure losses of 600 to 1200 Pa (except for Venturi and slot separators). Considerable pressure losses occur in the filtration layer. Their values depend on the layer porosity , diameter of filtration material fibres, layer thickness, gas dynamic viscosity and the velocity of the streaming gas. 

In comparison with dry mechanical separators, the wet separators exhibit a higher separation efficiency. High values can also be achieved for fine dusts. The separation efficiency of wet separators depends on the wett-... 

Wet separation of plastics is a microseparation method in which a suspension medium is used to separate plastics with density higher or lower than the suspension medium. For example, water can be used as medium to separate PE from PVC or PET. In this case, special tanks are used in which various types of plastic flaks are mixed with water and then given a sufiicient time to position themselves in the most suitable way according to their density. Materials are subsequently extracted separately from the top or bottom. This method is, however, not suitable for separating PVC from PET, because they have similar density. 

Various operations, to be carried out in a specific sequence because of the problems posed by the type of material, are grinding, dry separation, and wet separation. Machineries to be installed for these operations are dictated by the typology and quality of recycle items. 

Investment costs and energy usage for bag filters and wet separators are compared in Table 4.33. 

The exhaust air from the green sand preparation is saturated with water. Therefore, wet systems (often of the low pressure type) seem to be most suitable for exhaust capture. However, the wet system is widely being replaced by dry dust abatement. The latter has the advantage that part of the dust may be recirculated and that no waste water stream is generated. Additionally, the wet systems are prone to internal eorrosion and the build-up of dust and oxidation products. The wet separation of exhausted air impurities can result in problems for the waste water cleaning. Dust contains bentonite which is difficult to dispose of due to its anti-sedimentable effects. [225, TWG, 2003]... 

Powder separators must separate dry product from the drying air at the highest possible efficiency and collect the powder. Dry separators are used for the principal dry product separation and collection wet separators are used for the final air cleaning and hence are situated after dry collectors. 

This paper outlines procedures used in the identification of typical PVC formulations, starting with the resin and proceeding to impact modifier, process aids, lubricants, stabiliser system and fillers. The emphasis is on FTIR microscopy as the most versatile approach requiring small samples and minimal to no sample preparation. Other commonly used FTIR techniques are also outlined. Wet separation protocols, applicability and limitations as related to FTIR analysis are discussed. Typical examples include vinyl siding, packaging and bottle formulations as well as contaminants often encountered in these formulations and raw materials. 

Plastic-Plastic Separation Both dry and wet processes can be used to separate one plastic from another in a recycling operation. The most common wet separation methods are based on differences in density between particles of different plastics [1, 2, 10, 49], Density is a bulk property of the plastic. Unfortunately, many factors beyond polymer type affect density. Plastic particles can also show differences in surface properties. Plastic-plastic separation methods based on surface property differences include triboelectric separation [75] (a dry process) and froth flotation [75] (a wet process). Density-based and surface-property-based methods for separating a stream of mixed plastics are covered in the following sections. 

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