Sanding, mechanical

Secondary regeneration of green sand as a monosand flow finds limited implementation. For chemically-bonded sands, mechanical regeneration is most widely applied (>200 units in Germany in 1999) [80, ERM Lahmeyer International GmbH, 1999]. TTie applicability of the various regeneration techniques and of the regenerated sand are summarised in Table 4.59 (monosands) and Table 4.60 (mixed sand). Each of the presented techniques will be discussed in more detail in the sections below. 

Resol- ester methyl formate hardened sand Mechanical Mechanical friction, impact, pneumatic chafing With limitations, in mouldmaking with methyl formate sands - regeneration as resol-ester cold setting but with lower yield - embrittlement of binder components ... 

Green sand Mechanical pneumatic chafing, grinding Renewal sand for green sand circuit - requires predrying - re-use of fines 0.75... 

Sodium silicate sand Mechanical Only for making moulds and cores using sodium silicate sand Embrittlement of binder components at 200 °C 0.5... 

Mixed green and organic sand Mechanical-fhermal-mechanical treatment, grinding or pneumatic chafing in cores 40 - 100 in moulds 90 - 100... 

Table 22.1 Sand mechanical properties (After Mitrani 2006)...

Place 50 g. of o-chloronitrobenzene and 75 g. of clean dry sand in a 250 ml. flask equipped with a mechanical stirrer. Heat the mixture in an oil or fusible metal bath to 215-225° and add, during 40 minutes, 50 g. of copper bronze or, better, of activated copper bronze (Section 11,50, 4) (1), Maintain the temperature at 215-225° for a further 90 minutes and stir continuously. Pour the hot mixture into a Pyrex beaker containing 125 g. of sand and stir until small lumps are formed if the reaction mixture is allowed to cool in the flask, it will set to a hard mass, which can only be removed by breaking the flask. Break up the small lumps by powdering in a mortar, and boil them for 10 minutes with two 400 ml. 

Cation (Section 1 2) Positively charged ion Cellobiose (Section 25 14) A disacchande in which two glu cose units are joined by a 3(1 4) linkage Cellobiose is oh tamed by the hydrolysis of cellulose Cellulose (Section 25 15) A polysaccharide in which thou sands of glucose units are joined by 3(1 4) linkages Center of symmetry (Section 7 3) A point in the center of a structure located so that a line drawn from it to any element of the structure when extended an equal distance in the op posite direction encounters an identical element Benzene for example has a center of symmetry Cham reaction (Section 4 17) Reaction mechanism m which a sequence of individual steps repeats itself many times usu ally because a reactive intermediate consumed m one step is regenerated m a subsequent step The halogenation of alkanes is a chain reaction proceeding via free radical intermediates... 

M = mechanical transport of sands to discharge N = nonmechanical gravity or pressure S = sedimentation classifier and F = fiuidized-bed classifier. 

S, sand cast P, permanent mold cast D, pressure die cast. Aluminum and impurities constitute remainder. Table 22. Mechanical Properties of Aluminum Foundry Alloys ... 

Mechanical Gleaning. A cleaner is a hydrocyclone device utilizing fluid pressure to create rotational fluid motion (20). Pulp is introduced tangentially near the top of the cleaner. Contaminants denser than water such as chemically treated toner inks and sand migrate toward the outer wall of the cleaner and exit in a separate (reject) stream. For most forward cleaners, optimal ink removal efficiency is obtained at a pulp consistency of 0.2—0.3%. Most forward cleaners deinking efficiency declines at pulp feed consistencies greater than 0.4%. However, a cleaner said to be efficient at 1.2% pulp consistency has been reported (39). 

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